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Sample records for acoustic spark chambers

  1. spark chamber

    A few cosmic rays pass through your body every second of every day, no matter where you are. Look at the spark chamber to your right – every flash is the track made by a cosmic ray from outer space. The spark chamber is filled with a special gas mixture. Cosmic rays knock electrons out of the atoms in the gas. These electrons accelerate towards high voltage metal strips layered throughout the chamber, creating sparks like little bolts of lightning.

  2. spark chamber

    A few cosmic rays pass through your body every second of every day, no matter where you are. Look at the spark chamber to your right – every flash is the track made by a cosmic ray from outer space. The spark chamber is filled with a special gas mixture. Cosmic rays knock electrons out of the atoms in the gas. These electrons accelerate towards high voltage metal strips layered throughout the chamber, creating sparks like little bolts of lightning.

  3. Experiments with a spark chamber

    The authors constructed an experimental spark chamber with a useable volume of 7 x 7 x 5 cm having six parallel 2-mm thick stainless steel plates. The distance between each plate is 8 mm. The chamber is filled with neon under a pressure of one atmosphere. On applying a pulse of about 10 keV on the plates immediately after the passage of a charged particle through the chamber, sparks form along the trajectory of the particle and may easily be photographed. The chamber was first used with cosmic ray μ mesons and then put into the π-meson beam of the SATURN synchrocyclotron. The efficiency of the chamber as a function of voltage and retardation of the applied electric pulse and the dead time are given. The first results obtained with a chamber of 10-litre volume are also presented. (author)

  4. A spark-chamber spectrometer

    A programme of developing techniques for the construction and use of spark chambers in high-energy physics experiments has been undertaken. Several methods of construction have been tested and found satisfactory. One method is to cement aluminium plates to frames made from glass or Plexiglas strips. Another is to place the aluminium plates in grooves machined in Plexiglas, forming a ''shelf'' design. A chamber made of rows of wires was successfully operated with a He-alcohol mixture. These chambers can either be filled with gas and sealed, or gas can be passed through them continuously. Chambers have been constructed with plates of various thicknesses ranging from 0.032 in downwards. The operation of the chambers with various spacings between the plates was also investigated. The performance of these chambers, when filled with several different gases (Ne, He, A) and with gas-alcohol mixtures, has been investigated. Several methods of applying high-voltage pulses to the chambers have been attempted. The results of these investigations are presented. Spark chambers placed in a magnetic field can be used in principle to determine the momentum of charged particles and if lead converter-plates are incorporated with them, the resulting system should serve as a gamma-ray spectrometer of high resolution and high efficiency. A magnet with an 18-in useful diameter and a 13000-G field is being fitted with spark chambers, whose performance will be tested with cosmic rays and with an accelerator beam. Results from such tests are presented. (author)

  5. Guard wires in spark chambers

    The experiments with spark counters have shown that by surrounding the anode wire with two wires of a larger diameter, an increase of the detection efficiency of about 25% is observed. The analysis of the amplitudes of the pulses in those guard wires with the coincident pulses in the anode wire shows that is is possible to determine. The ionizing particle incidence position with rather simple and conventional electronic circuitry. (author). 5 refs, 7 figs

  6. Radiofrequency spark chambers and delay line resonators

    According to a suggestion of A. Kastler, a spark chamber was excited by an undamped radiofrequency pulse and tracks about 1 mm wide obtained; the result was interpreted by computation of the coefficients of electronic amplification and partial ambipolar diffusion. This work led us to the construction of a new fast triggering undamped wave-train generator of very high tension (patent taken out by the C.E.A. under the no.: EN 7 134 650 the 27.9.1971). Since this apparatus uses a resonant storage line, its design implied a precise knowledge of high impedance delay lines. The experimental radiofrequency spectra of the input impedance of opened or short-circuited lines were plotted completely and analysed by the circuits theory, new measuring methods were established, dispersion relations accurately checked and the equivalence of the formulas, within the third order, with theses of Debye's Dipolar Absorption demonstrated. General properties of Hilbert's transform were also investigated. From the experimental point of view, the electromagnetic energy storage process was extended to the case of a liquid nitrogen-immersed resonant delay line. The good behavior of the cryogenic experiment, where the main difficulty of icing was overcame by the construction of special electrodes, offers great promise for extrapolation to superconductivity. (author)

  7. Assembly of optical spark chambers for the experiment Nue

    1974-01-01

    To continue the research on neutral currents after their discovery in Gargamelle in 1973, the Aachen-Padua Collaboration set up in the neutrino beam of the PS South-East Area, behind Gargamelle, an assembly of 150 optical spark chambers, 2x2 m2 extending over 8 m (experiment T230, Nue). Hans Reithler stands on the right.

  8. Postdischarge deionization in small-gap spark chambers

    The recovery of the pulse electrical strength of spark chambers with electrodes out of aluminium foil for two values of the interelectrode gap (1.0 and 0.6) has been investigated experimentally in relation to the electric conditions and composition of the gas mixture. The spark chambers have been filled with Ne + He, Ne, and He at atmospheric pressure with the addition of a few percent ethanol vapor, isopropanol vapour, and 0.01% freon-12. The curves of the electrical strength recovery time as a function of the clearing field potential are shown, as well as the extrapolated values of the reduction time versus the clearing field potential. The obtained numerical results are tabulated. The recovery time is shown to be determined to a considerable degree by the drift time of the ion column and the concominant secondary processes, i.e. secondary electron emission from the collisions of the noble gas ions with the electrodes, the charge-exchange between the Ne+ (or He+) ions and spirit molecules

  9. Wire spark chamber capacitive readout system with low leakage current and small systematic error

    Anderhub, H.B.; Boecklin, J.; von Gunten, H.P.; Koenig, H.; Le Coultre, P.; Makowiecki, D.; Seiler, P.G. (Eidgenoessische Technische Hochschule, Zurich (Switzerland). Lab. fuer Hochenergiephysik)

    1983-02-15

    A wire spark chamber capacitive readout system with analog FET switch multiplexing and CAMAC interface is described. Two wire planes per chamber are read out. The information of each plane is sequentially digitized in one ADC. This and the low leakage current of the FET switches guarantee a small systematic error of the measurement of the spark position.

  10. A wire spark chamber capacitive readout system woth low leakage current and small systematic error

    A wire spark chamber capacitive readout system with analog FET switch multiplexing and CAMAC interface is described. Two wire planes per chamber are read out. The information of each plane is sequentially digitized in one ADC. This and the low leakage current of the FET switches guarantee a small systematic error of the measurement of the spark position. (orig.)

  11. Combined Environment Acoustic Chamber (CEAC)

    Federal Laboratory Consortium — Purpose: The CEAC imposes combined acoustic, thermal and mechanical loads on aerospace structures. The CEAC is employed to measure structural response and determine...

  12. Liquid rocket combustion chamber acoustic characterization

    Cândido Magno de Souza

    2010-09-01

    Full Text Available Over the last 40 years, many solid and liquid rocket motors have experienced combustion instabilities. Among other causes, there is the interaction of acoustic modes with the combustion and/or fluid dynamic processes inside the combustion chamber. Studies have been showing that, even if less than 1% of the available energy is diverted to an acoustic mode, combustion instability can be generated. On one hand, this instability can lead to ballistic pressure changes, couple with other propulsion systems such as guidance or thrust vector control, and in the worst case, cause motor structural failure. In this case, measures, applying acoustic techniques, must be taken to correct/minimize these influences on the combustion. The combustion chamber acoustic behavior in operating conditions can be estimated by considering its behavior in room conditions. In this way, acoustic tests can be easily performed, thus identifying the cavity modes. This paper describes the procedures to characterize the acoustic behavior in the inner cavity of four different configurations of a combustion chamber. Simple analytical models are used to calculate the acoustic resonance frequencies and these results are compared with acoustic natural frequencies measured at room conditions. Some comments about the measurement procedures are done, as well as the next steps for the continuity of this research. The analytical and experimental procedures results showed good agreement. However, limitations on high frequency band as well as in the identification of specific kinds of modes indicate that numerical methods able to model the real cavity geometry and an acoustic experimental modal analysis may be necessary for a more complete analysis. Future works shall also consider the presence of passive acoustic devices such as baffles and resonators capable of introducing damping and avoiding or limiting acoustic instabilities.

  13. Liquid rocket combustion chamber acoustic characterization

    Cândido Magno de Souza; Luiz Carlos Sandoval Góes; Dimas Donizeti da Silveira; Rogério Pirk; Carlos d’Andrade Souto

    2010-01-01

    Over the last 40 years, many solid and liquid rocket motors have experienced combustion instabilities. Among other causes, there is the interaction of acoustic modes with the combustion and/or fluid dynamic processes inside the combustion chamber. Studies have been showing that, even if less than 1% of the available energy is diverted to an acoustic mode, combustion instability can be generated. On one hand, this instability can lead to ballistic pressure changes, couple with other propulsion...

  14. Acoustical-Levitation Chamber for Metallurgy

    Barmatz, M. B.; Trinh, E.; Wang, T. G.; Elleman, D. D.; Jacobi, N.

    1983-01-01

    Sample moved to different positions for heating and quenching. Acoustical levitation chamber selectively excited in fundamental and second-harmonic longitudinal modes to hold sample at one of three stable postions: A, B, or C. Levitated object quickly moved from one of these positions to another by changing modes. Object rapidly quenched at A or C after heating in furnace region at B.

  15. Wave Phenomena in an Acoustic Resonant Chamber

    Smith, Mary E.; And Others

    1974-01-01

    Discusses the design and operation of a high Q acoustical resonant chamber which can be used to demonstrate wave phenomena such as three-dimensional normal modes, Q values, densities of states, changes in the speed of sound, Fourier decomposition, damped harmonic oscillations, sound-absorbing properties, and perturbation and scattering problems.…

  16. New types of spark-chambers for imaging γ or x emitters, and their medical applications

    In order to adapt spark-chambers to low-energy particles, a first attempt was made using a two-electrode device operating as a proportional counter. The signal obtained triggers a high-voltage pulse which is applied to the same device and a spark occurs near the track of the particle. A three-electrode device including a detection space associated to the sparks space was then used. It was noticed that the spark was formed spontaneously at the point where the particle passed, when suitable direct-current voltages were applied to the electrodes; the high voltage is slightly lower than on the other types of chamber. This phenomenon makes the three-electrode device very easy to use for X or γ rays. The characteristics of the first device filled with argon and methane are given and the first results obtained in the medical field with a device filled with xenon methylal are presented. (author)

  17. Performance and spark damage studies of microgap gas chambers fabricated with selected anode metals

    Microgap gas chambers (MGCs) fabricated with selected anode metals, including aluminum, gold, chromium, nickel and titanium/tungsten (10/90) have been used in order to study the effect of these different metals upon gas gain, aging, and spark damage. Gas mixtures used for systematic tests of performance are argon/ethane (50/50) and argon/dimethyl ether (50/50). The effects of spark damage by discharge are found to be very sensitive to the metal used for anode strips, and a systematic study of spark damage effects has been made to compare their relative sensitivity to failure, over a range of electrical discharge energies. (orig.)

  18. Reconstruction of data for an experiment using multi-gap spark chambers with six-camera optics

    A program has been developed to reconstruct spark positions in a pair of multi-gap optical spark chambers viewed by six cameras, which were used by a Rutherford Laboratory experiment. The procedure for correlating camera views to calculate spark positions is described. Calibration of the apparatus, and the application of time- and intensity-dependent corrections are discussed. (author)

  19. X-ray emission of pseudo spark chambers

    Three types of X-ray sources can be classified in the high power Pseudo Spark: anode radiation, which is generated by the self-focused electron beam during the predischarge, radiation from the cathode surface, which has its origin in electrons hitting the walls at the beginning of the main discharge, and plasma radiation, which is emitted partially directed by a small plasma area in the hollow cathode region during the main discharge. The maximum quantum energies of anode and cathode wall radiation are corresponding to the discharge voltage, those of the plasma radiation are typically one to two orders of magnitude lower. The measurement of the X-ray emission is supporting the usual distinction of pre- and main discharge in the Pseudo Spark. Additionally can be shown, that the predischarge consists of a modified Townsend discharge with runaway-electrons in the discharge channel and a normal Townsend discharge with drifting electrons in the hollow cathode region. The events in the hollow cathode region are essential for the transition into the main discharge. A first application of the Pseudo Spark as an X-ray source was realised in an experimental upset for X-ray backlightning of ion beam targets. (orig.)

  20. Automatic digitization of optical spark chamber data using charge coupled devices

    A system of charge-coupled imagers capable of recording optical spark chamber data has been developed. The operation of charge-coupled devices (CCD's) is discussed and details of systems utilizing single and multiple CCD imagers are presented. Data taken using a multiple CCD system in parallel with film are given. CCD sensitivity, spatial resolution and accuracy are discussed and comparisons are made between CCD data and that obtained from film

  1. Automatic digitization of optical spark chamber data using charge coupled devices

    A system of charge-coupled imagers capable of recording optical spark chamber data has been developed. The operation of charge-coupled devices (CCDs) is discussed and details of systems utilizing single and multiple CCD imagers are presented. Data taken using a multiple CCD system in parallel with film are given. CCD sensitivity, spatial resolution and accuracy are discussed and comparisons are made between CCD data and that obtained from film. (orig.)

  2. Enhancement of flame development by microwave-assisted spark ignition in constant volume combustion chamber

    Wolk, Benjamin

    2013-07-01

    The enhancement of laminar flame development using microwave-assisted spark ignition has been investigated for methane-air mixtures at a range of initial pressures and equivalence ratios in a 1.45. l constant volume combustion chamber. Microwave enhancement was evaluated on the basis of several parameters including flame development time (FDT) (time for 0-10% of total net heat release), flame rise time (FRT) (time for 10-90% of total net heat release), total net heat release, flame kernel growth rate, flame kernel size, and ignitability limit extension. Compared to a capacitive discharge spark, microwave-assisted spark ignition extended the lean and rich ignition limits at all pressures investigated (1.08-7.22. bar). The addition of microwaves to a capacitive discharge spark reduced FDT and increased the flame kernel size for all equivalence ratios tested and resulted in increases in the spatial flame speed for sufficiently lean flames. Flame enhancement is believed to be caused by (1) a non-thermal chemical kinetic enhancement from energy deposition to free electrons in the flame front and (2) induced flame wrinkling from excitation of flame (plasma) instability. The enhancement of flame development by microwaves diminishes as the initial pressure of the mixture increases, with negligible flame enhancement observed above 3. bar. © 2013 The Combustion Institute.

  3. Wide-gap large spark chamber supplying by high-voltage radio pulse

    In the process of avalanche formation in wide-gap (2 gaps 15 cm each) spark chambers when supplying them by high-voltage pulse (field intensity is 5.7-7.0 kV/cm, pulse duration-250-150 ns) of unipolar shape, a directed drift of charges in electric field takes place, which results in the shift of the track photographed as to actual particle tra ectory. To decrease the shift in the process of chamber supply a high-voltage radio pulse was used, which presented an attenuatina sinusoid. When supplying the chamber by sign-alternating pulse the shift constitutes 0.16+-0.15 mm, and the angle - 5.3x10-5+- 1.1x10-3 rad. When supplying by unipolar pulse the shift eqUals O.58+-0.40 mm, and the angle - 1.5x10-4+-2.5x10-3 rad. The use of sign-alternating supply permitted to increase the accuracy of track localization and to decrease the dependence of track brightness on the angle of particle entrance to the chamber

  4. Acoustic Sensor Design for Dark Matter Bubble Chamber Detectors

    Ivan Felis; Juan Antonio Martínez-Mora; Miguel Ardid

    2016-01-01

    Dark matter bubble chamber detectors use piezoelectric sensors in order to detect and discriminate the acoustic signals emitted by the bubbles grown within the superheated fluid from a nuclear recoil produced by a particle interaction. These sensors are attached to the outside walls of the vessel containing the fluid. The acoustic discrimination depends strongly on the properties of the sensor attached to the outer wall of the vessel that has to meet the requirements of radiopurity and size. ...

  5. Improving the performance and fuel consumption of dual chamber stratified charge spark ignition engines

    Sorenson, S.C.; Pan, S.S.; Bruckbauer, J.J.; Gehrke, G.R.

    1979-09-01

    A combined experimental and theoretical investigation of the nature of the combustion processes in a dual chamber stratified charge spark ignition engine is described. This work concentrated on understanding the mixing process in the main chamber gases. A specially constructed single cylinder engine was used to both conduct experiments to study mixing effects and to obtain experimental data for the validation of the computer model which was constructed in the theoretical portion of the study. The test procedures are described. Studies were conducted on the effect of fuel injection timing on performance and emissions using the combination of orifice size and prechamber to main chamber flow rate ratio which gave the best overall compromise between emissions and performance. In general, fuel injection gave slightly higher oxides of nitrogen, but considerably lower hydrocarbon and carbon monoxide emissions than the carbureted form of the engine. Experiments with engine intake port redesign to promote swirl mixing indicated a substantial increase in the power output from the engine and, that an equivalent power levels, the nitric oxide emissions are approximately 30% lower with swirl in the main chamber than without swirl. The development of a computer simulation of the combustion process showed that a one-dimensional combustion model can be used to accurately predict trends in engine operation conditions and nitric oxide emissions even though the actual flame in the engine is not completely one-dimensional, and that a simple model for mixing of the main chamber and prechamber intake gases at the start of compression proved adequate to explain the effects of swirl, ignition timing, overall fuel air ratio, volumetric efficiency, and variations in prechamber air fuel ratio and fuel rate percentage on engine power and nitric oxide emissions. (LCL)

  6. Laser measuring system for incremental assemblies. [measuring wire-wrapped frame assemblies in spark chambers

    Etzel, J. G.; Munford, J. A. (Inventor)

    1981-01-01

    Wire-wrapped frame assemblies used in spark chambers and the like can be measured using a system which utilizes a laser, an interferometer, and a retroreflector to precisely measure distance. A light source and a photodetector are located adjacent the incremental assembly and mounted on a movable carriage. The interferometer is also mounted on the movable carriage, while the laser and retroreflector are positioned at either end of the carriage track. The carriage is moved along one edge of the incremental assembly between the retroreflector and the laser, and as the carriage is moved, the light from the light source to the photodetector is interrupted. This produces a trigger command to a control unit which in turn causes a distance measurement to be made. A printout is provided for each sampling trigger command to list such items as ideal position, actual position and amount of error.

  7. Micro acoustic resonant chambers for heating/agitating/mixing (MARCHAM)

    Sherrit, Stewart; Noell, Aaron C.; Fisher, Anita M.; Takano, Nobuyuki; Grunthaner, Frank

    2016-04-01

    A variety of applications require the mixing and/or heating of a slurry made from a powder/fluid mixture. One of these applications, Sub Critical Water Extraction (SCWE), is a process where water and an environmental powder sample (sieved soil, drill cuttings, etc.) are heated in a sealed chamber to temperatures greater than 200 degrees Celsius by allowing the pressure to increase, but without reaching the critical point of water. At these temperatures, the ability of water to extract organics from solid particulate increases drastically. This paper describes the modeling and experimentation on the use of an acoustic resonant chamber which is part of an amino acid detection instrument called Astrobionibbler [Noell et al. 2014, 2015]. In this instrument we use acoustics to excite a fluid- solid fines mixture in different frequency/amplitude regimes to accomplish a variety of sample processing tasks. Driving the acoustic resonant chamber at lower frequencies can create circulation patterns in the fluid and mixes the liquid and fines, while driving the chamber at higher frequencies one can agitate the fluid and powder and create a suspension. If one then drives the chamber at high amplitude at resonance heating of the slurry occurs. In the mixing and agitating cell the particle levitation force depends on the relative densities and compressibility's of the particulate and fluid and on the kinetic and potential energy densities associated with the velocity and pressure fields [Glynne-Jones, Boltryk and Hill 2012] in the cell. When heating, the piezoelectric transducer and chamber is driven at high power in resonance where the solid/fines region is modelled as an acoustic transmission line with a large loss component. In this regime, heat is pumped into the solution/fines mixture and rapidly heats the sample. We have modeled the piezoelectric transducer/chamber/ sample using Mason's equivalent circuit. In order to assess the validity of the model we have built and

  8. Data registration units of a modified magnetostrictive multiwire spark chamber system of the ''Foton'' set-up

    Data registration units of a modified magnetostrictive spark chamber system of the ''Foton'' set-up are described. The circuits, the specifications and time diagrams of time converters and control Units of recording appraratus are given. The P101M time-digital converter (TDC) allows one to register 4 ''sparks'', the P105 TDG-4x16 ''sparks'' at a duration coding interval up to 819 mks. The coding frequency is 20 MHz. The units could be used in parallel-sequential units and parallel registration systems. The G-104 test generator is used to test the registration electronic equipment. It generates the pulse sequence with adjustable number and time interval duration, which stability is determined by parameters of a master generator

  9. Acoustic Sensor Design for Dark Matter Bubble Chamber Detectors.

    Felis, Ivan; Martínez-Mora, Juan Antonio; Ardid, Miguel

    2016-01-01

    Dark matter bubble chamber detectors use piezoelectric sensors in order to detect and discriminate the acoustic signals emitted by the bubbles grown within the superheated fluid from a nuclear recoil produced by a particle interaction. These sensors are attached to the outside walls of the vessel containing the fluid. The acoustic discrimination depends strongly on the properties of the sensor attached to the outer wall of the vessel that has to meet the requirements of radiopurity and size. With the aim of optimizing the sensor system, a test bench for the characterization of the sensors has been developed. The sensor response for different piezoelectric materials, geometries, matching layers, and backing layers have been measured and contrasted with FEM simulations and analytical models. The results of these studies lead us to have a design criterion for the construction of specific sensors for the next generation of dark matter bubble chamber detectors (250 L). PMID:27294937

  10. Multipurpose council chambers ``in the round'' poses acoustical challenges

    Logsdon, Edward L.

    2003-10-01

    The City of Aurora Council Chambers is used for both municipal and public meetings. The room is configured to provide close-in seating with good sightlines from each of the 300 stadium-style seats. Presentations can be made from the central podium location to either the audience or council dais requiring multiple loudspeaker zoning and control. The cylindrical ceiling, shaped to accommodate video projection and lighting equipment, is acoustically treated to eliminate late reflections. The City Council meetings are broadcast to public TV on a regular basis from this room requiring good room acoustics and sound isolation to reduce echo and achieve acceptably low background noise levels while satisfying the aesthetic palette of the interior designers. A case history will be presented along with photographs showing how specialty wood materials, both absorptive and diffusive, were incorporated along with absorptive plaster and cloth-covered fiberglass panels into the design of the building.

  11. Quasi-dimensional modeling of a fast-burn combustion dual-plug spark-ignition engine with complex combustion chamber geometries

    This study builds on a previous parametric investigation using a thermodynamic-based quasi-dimensional (QD) cycle simulation of a spark-ignition (SI) engine with dual-spark plugs. The previous work examined the effects of plug-number and location on some performance parameters considering an engine with a simple cylindrical disc-shaped combustion chamber. In order to provide QD thermodynamic models applicable to complex combustion chamber geometries, a novel approach is considered here: flame-maps, which utilizes a computer aided design (CAD) software (SolidWorks). Flame maps are produced by the CAD software, which comprise all the possible flame radiuses with an increment of one-mm between them, according to the spark plug positions, spark timing, and piston position near the top dead center. The data are tabulated and stored as matrices. Then, these tabulated data are adapted to the previously reported cycle simulation. After testing for simple disc-shaped chamber geometries, the simulation is applied to a real production automobile (Honda-Fit) engine to perform the parametric study. - Highlights: • QD model was applied in dual plug engine with complex realistic combustion chamber. • This method successfully modeled the combustion in the dual-plug Honda-Fit engine. • The same combustion chamber is tested for various spark plug(s) locations. • The centrally located single spark-plug results in the fastest combustion

  12. Acoustic coupling between cascade sub-chambers and its influence on overall transmission loss

    Tong, Yuhui; Pan, Jie

    2015-01-01

    In this letter, acoustic interaction between cascade sub-chambers is investigated by modelling the sound field in a silencer with cascade-connected sub-chambers using a sub-structuring technique. The contribution of the acoustic coupling to the net energy flow through each individual sub-chamber is derived quantitatively and the mechanism by which evanescence contributes to the sound transmission loss of the silencer is revealed.

  13. Environmental Impact of Increased Consumption of Engine Oil in the Combustion Chamber of a Spark Ignited Engine

    O.S. Udeozor

    2011-09-01

    Full Text Available Blue smoke is a classic sign of oil consumption in the engine and the major causes of these emissions are found to be worn-out piston rings, valve seals and valve guides. These causes are the resultant effect of increased oil consumption in the internal combustion engine, leading to excessive release of harmful exhaust emissions. This study is aimed at looking at the environmental impact of such increased oil consumption, by collecting exhaust samples from some vehicles that have oil consumption problems, using the Exhaust Gas Analyzer. Thereafter the pollutants are analyzed and estimated to determine their concentration and consequential impact on the environment. The result obtained showed that excessive engine oil consumed in the combustion chamber of the spark ignited engine can lead to high concentration of pollutants (NOX, CO, CxHy released into the environment.

  14. Spin Start Line Effects on the J2X Gas Generator Chamber Acoustics

    Kenny, R. Jeremy

    2011-01-01

    The J2X Gas Generator engine design has a spin start line connected near to the turbine inlet vanes. This line provides helium during engine startup to begin turbomachinery operation. The spin start line also acts as an acoustic side branch which alters the chamber's acoustic modes. The side branch effectively creates 'split modes' in the chamber longitudinal modes, in particular below the first longitudinal mode and within the frequency range associated with the injection-coupled response of the Gas Generator. Interaction between the spin start-modified chamber acoustics and the injection-driven response can create a higher system response than without the spin start attached to the chamber. This work reviews the acoustic effects of the spin start line as seen throughout the workhorse gas generator test program. A simple impedance model of the spin start line is reviewed. Tests were run with no initial spin start gas existing in the line, as well as being initially filled with nitrogen gas. Tests were also run with varying spin start line lengths from 0" to 40". Acoustic impedance changes due to different spin start gas constituents and line lengths are shown. Collected thermocouple and static pressure data in the spin start line was used to help estimate the fluid properties along the line length. The side branch impedance model was coupled to a chamber impedance model to show the effects on the overall chamber response. Predictions of the spin start acoustic behavior for helium operation are shown and compared against available data.

  15. Some recent results for nonlinear acoustics in combustion chambers

    Culick, F. E. C.

    1990-01-01

    Conditions of high energy densities and low losses in combustion chambers encourage the excitation and sustenance of organized unsteady motions generically called combustion instabilities. The fluctuations, common in propulsion systems, often reach sufficient amplitudes to cause excessive rates of heat transfer to exposed surfaces and unacceptable structural vibrations, causing failure in extreme cases. In many cases, to avoid the occurrence of instabilities, combustion chambers are ...

  16. Anisotropic Elastic and Acoustic Properties of Bulk Graphene Nanoplatelets Consolidated by Spark Plasma Sintering

    Koller, M.; Seiner, Hanuš; Landa, Michal; Nieto, A.; Agarwal, A.

    Praha : Department of Physics of Materials, Charles University in Prague, 2014. [ISPMA /13./. 31.08.2014-04.09.2014, Praha] R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61388998 Keywords : spark plasma sintering * resonant ultrasound spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism

  17. Acoustic and Large Eddy Simulation studies of azimuthal modes in annular combustion chambers

    Wolf, Pierre; Staffelbach, Gabriel; Gicquel, Laurent Y.M.; Müller, Jens-Dominik; Poinsot, Thierry

    2012-01-01

    International audience The objectives of this paper are the description of azimuthal instability modes found in annular combus- tion chambers using two numerical tools: (1) Large Eddy Simulation (LES) methods and (2) acoustic solv- ers. These strong combustion instabilities are difficult to study experimentally and the present study is based on a LES of a full aeronautical combustion chamber. The LES exhibits a self-excited oscillation at the frequency of the first azimuthal eigenmode. The...

  18. Anisotropic Elastic and Acoustic Properties of Bulk Graphene Nanoplatelets Consolidated by Spark Plasma Sintering

    Koller, M.; Seiner, Hanuš; Landa, Michal; Nieto, A.; Agarwal, A.

    2015-01-01

    Roč. 128, č. 4 (2015), s. 670-674. ISSN 0587-4246. [International Symposium on Physics of Materials (ISPMA) /13./. Praha, 31.08.2015-04.09.2015] R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61388998 Keywords : graphene nanoplatelets * anisotropy * resonant ultrasound spectroscopy * SPS * elastic constants Subject RIV: BI - Acoustics Impact factor: 0.530, year: 2014 http://przyrbwn.icm.edu.pl/APP/ABSTR/128/a128-4-49.html

  19. Two Years of Industrial Experience in the Use of a Small, Direct Field Acoustic Chamber

    Saggini, Nicola; Di Pietro, Vincenzo; Poulain, Nicolas; Herzog, Philippe

    2012-07-01

    Within Thales Alenia Space - Italy small satellite Assembly Integration and Test (AIT) plant, the need to develop a suitable facility for spacecraft acoustic noise test has arisen, with additional constraints posed by the necessity of a low impact on the existing building layout, low cost of procurement and operations, while maintaining a high reliability of the system for a theoretical maximum throughput of one test per week over an extended period of time, e.g. six months. The needs have been answered by developing a small (~40 m3 test volume), direct field (DF A T) acoustic test chamber, christened “Alpha Cabin”, where noise generation is achieved by means of commercial audio drivers equipped with custom enclosures. The paper starts with a brief presentation of the main characteristics of the system, but then concentrates on the lessons learnt and return of experience from the tests conducted in more than two years of continuous use. Starting from test article structural responses and their comparison with reverberant chambers, properties of the acoustic field and their implications on the former are analyzed.

  20. The Harmonic Response Analysis with Acoustic-vibration Coupling of the Combustion Chamber under Different Combustion Conditions

    Zheng Min

    2016-01-01

    Full Text Available In this paper, numerical calculations of harmonic response with acoustic-vibration coupling of the combustion chamber under different combustion conditions has been performed by combining CFD and FEM methods. Temperature and sound pressure fields created by the flame in the combustion chamber are calculated first. And then the results of the CFD are exported to the FEM analysis for the interaction between acoustic waves and wall vibrations. The possible acoustic-vibration coupled eigenfrequencies at given combustion conditions are predicted by the harmonic response analysis.

  1. Giuseppe and Maria Fidecaro inside the Spark Chamber Apparatus in the South Hall of PS to search for the $\\rho \\rightarrow \\pi\\gamma$ decay

    Gérard Bertin

    1964-01-01

    A year after the commissioning of the Synchrocyclotron (SC), the first experiments were already starting to bear fruit. In July 1958, Tito Fazzini, Giuseppe Fidecaro, Alec Merrison, Helmut Paul and Alvin Tollestrup produced conclusive evidence that approximately one pion in ten thousand decayed into an electron and a neutrino, as predicted by the weak interaction theory. This, the first of CERN's great discoveries, effectively put an end to the controversy that had been raging at the time. A few years later, Giuseppe Fidecaro began a collaboration at CERN with his wife Maria. In the image, Giuseppe and Maria Fidecaro in 1963, surrounded by spark chambers, inside the detector for the experiment on the decay of a rho meson into a pi meson and a photon.

  2. An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Article's Absorption during Reverberant Chamber Acoustic Testing of Spaceflight Hardware

    Hozman, Aron D.; Hughes, William O.

    2014-01-01

    The exposure of a customers aerospace test-article to a simulated acoustic launch environment is typically performed in a reverberant acoustic test chamber. The acoustic pre-test runs that will ensure that the sound pressure levels of this environment can indeed be met by a test facility are normally performed without a test-article dynamic simulator of representative acoustic absorption and size. If an acoustic test facilitys available acoustic power capability becomes maximized with the test-article installed during the actual test then the customers environment requirement may become compromised. In order to understand the risk of not achieving the customers in-tolerance spectrum requirement with the test-article installed, an acoustic power margin evaluation as a function of frequency may be performed by the test facility. The method for this evaluation of acoustic power will be discussed in this paper. This method was recently applied at the NASA Glenn Research Center Plum Brook Stations Reverberant Acoustic Test Facility for the SpaceX Falcon 9 Payload Fairing acoustic test program.

  3. Equilibrium shape and location of a liquid drop acoustically positioned in a resonant rectangular chamber

    Jackson, H. W.; Barmatz, M.; Shipley, C.

    1988-01-01

    The effect of a standing wave field in a rectangular chamber on the shape and location of an acoustically positioned drop or bubble is calculated. The sample deformation and equilibrium position are obtained from an analysis of the spherical harmonic projections of the total surface stress tensor. The method of calculation relies on the assumed condition that the sample is only slightly distorted from a spherical form. The equilibrium location of a levitated drop is combined with a formula introduced by Hasegawa (1979) to calcualte the ka dependence of the radiation force function. The present theory is valid for large as well as small ka values. Calculations in the small ka limit agree with previous theories and experimental results. Examples are presented for nonplane-wave modes as well as plane-wave rectangular modes.

  4. Bubbles, sparks, and the postwar laboratory

    The development and use of bubble chambers and spark chambers in the 1950s form the main thrust of this article, the bubble chamber as an example of ''image-producing'' instruments and the spark chamber as a ''logic'' device. Work on a cloud chamber by Glaser led to the development of the bubble chamber detector using liquid hydrogen, which was later linked to a computer for accurate automatic track analysis. It made possible demonstrations of the existence of a particle or interaction. Spark chambers were easier to build and so soon became common, various types being developed across the world. The development of spark chambers originated in the need for timing devices for the Manhattan Project, but work on their design occurred in a number of units worldwide. (UK)

  5. Efficiency calibration of solid track spark auto counter

    The factors influencing detection efficiency of solid track spark auto counter were analyzed, and the best etch condition and parameters of charge were also reconfirmed. With small plate fission ionization chamber, the efficiency of solid track spark auto counter at various experiment assemblies was re-calibrated. The efficiency of solid track spark auto counter at various experimental conditions was obtained. (authors)

  6. A review of acoustic dampers applied to combustion chambers in aerospace industry

    Zhao, Dan; Li, X. Y.

    2015-04-01

    In engine combustion systems such as rockets, aero-engines and gas turbines, pressure fluctuations are always present, even during normal operation. One of design prerequisites for the engine combustors is stable operation, since large-amplitude self-sustained pressure fluctuations (also known as combustion instability) have the potential to cause serious structural damage and catastrophic engine failure. To dampen pressure fluctuations and to reduce noise, acoustic dampers are widely applied as a passive control means to stabilize combustion/engine systems. However, they cannot respond to the dynamic changes of operating conditions and tend to be effective over certain narrow range of frequencies. To maintain their optimum damping performance over a broad frequency range, extensive researches have been conducted during the past four decades. The present work is to summarize the status, challenges and progress of implementing such acoustic dampers on engine systems. The damping effect and mechanism of various acoustic dampers, such as Helmholtz resonators, perforated liners, baffles, half- and quarter-wave tube are introduced first. A summary of numerical, experimental and theoretical studies are then presented to review the progress made so far. Finally, as an alternative means, ';tunable acoustic dampers' are discussed. Potential, challenges and issues associated with the dampers practical implementation are highlighted.

  7. Chamber Hall Threshold Design and Acoustic Surface Shaping with Parametric Modeling

    Garber, Emily Ann

    2011-01-01

    The architectural opportunity to develop the sound and light lock of a performance venue as a space that engages and prepares the audience for a performance is one that is sadly missing from most halls. I have explored the development of this threshold as a true architectural space, one that enhances the overall experience for the audience members. And by introducing a parametric process into the architectural and acoustic development, have proposed a unique process for the design of concert ...

  8. A Spinal Cord Window Chamber Model for In Vivo Longitudinal Multimodal Optical and Acoustic Imaging in a Murine Model

    Maeda, Azusa; Conroy, Leigh; McMullen, Jesse D.; Silver, Jason I.; Stapleton, Shawn; Vitkin, Alex; Lindsay, Patricia; Burrell, Kelly; Zadeh, Gelareh; Fehlings, Michael G.; DaCosta, Ralph S.

    2013-01-01

    In vivo and direct imaging of the murine spinal cord and its vasculature using multimodal (optical and acoustic) imaging techniques could significantly advance preclinical studies of the spinal cord. Such intrinsically high resolution and complementary imaging technologies could provide a powerful means of quantitatively monitoring changes in anatomy, structure, physiology and function of the living cord over time after traumatic injury, onset of disease, or therapeutic intervention. However, longitudinal in vivo imaging of the intact spinal cord in rodent models has been challenging, requiring repeated surgeries to expose the cord for imaging or sacrifice of animals at various time points for ex vivo tissue analysis. To address these limitations, we have developed an implantable spinal cord window chamber (SCWC) device and procedures in mice for repeated multimodal intravital microscopic imaging of the cord and its vasculature in situ. We present methodology for using our SCWC to achieve spatially co-registered optical-acoustic imaging performed serially for up to four weeks, without damaging the cord or induction of locomotor deficits in implanted animals. To demonstrate the feasibility, we used the SCWC model to study the response of the normal spinal cord vasculature to ionizing radiation over time using white light and fluorescence microscopy combined with optical coherence tomography (OCT) in vivo. In vivo power Doppler ultrasound and photoacoustics were used to directly visualize the cord and vascular structures and to measure hemoglobin oxygen saturation through the complete spinal cord, respectively. The model was also used for intravital imaging of spinal micrometastases resulting from primary brain tumor using fluorescence and bioluminescence imaging. Our SCWC model overcomes previous in vivo imaging challenges, and our data provide evidence of the broader utility of hybridized optical-acoustic imaging methods for obtaining multiparametric and rich

  9. The suppression of destructive sparks in parallel plate proportional counters

    The authors find that high energy background events produce localised sparks in parallel plate counters when operated in the proportional mode. These sparks increase dead-time and lead to degradation ranging from electrode damage to spurious pulsing and continuous breakdown. The problem is particularly serious in low energy photon detectors for X-ray astronomy which are required to have lifetimes of several years in the high radiation environment of space. For the parallel plate imaging detector developed for the European X-ray Observatory Satellite (EXOSAT) they investigate quantitatively the spark thresholds, spark rates and degradation processes. They discuss the spark mechanism, pointing out differences from the situation in spark chambers and counters. They show that the time profile of the sparks allows them to devise a spark suppression system which reduces the degradation rate by a factor of ''200

  10. Spark ablation device

    Schmidt-Ott, A.; Pfeiffer, T.V.

    2013-01-01

    A spark ablation device for generating nanoparticles comprising a spark generator; the spark generator comprising first and second electrodes, wherein the spark generator further comprises at least one power source which is arranged to be operative at a first energy level for maintaining a discharge

  11. Capabilities, Design, Construction and Commissioning of New Vibration, Acoustic, and Electromagnetic Capabilities Added to the World's Largest Thermal Vacuum Chamber at NASA's Space Power Facility

    Motil, Susan M.; Ludwiczak, Damian R.; Carek, Gerald A.; Sorge, Richard N.; Free, James M.; Cikanek, Harry A., III

    2011-01-01

    NASA s human space exploration plans developed under the Exploration System Architecture Studies in 2005 included a Crew Exploration Vehicle launched on an Ares I launch vehicle. The mass of the Crew Exploration Vehicle and trajectory of the Ares I coupled with the need to be able to abort across a large percentage of the trajectory generated unprecedented testing requirements. A future lunar lander added to projected test requirements. In 2006, the basic test plan for Orion was developed. It included several types of environment tests typical of spacecraft development programs. These included thermal-vacuum, electromagnetic interference, mechanical vibration, and acoustic tests. Because of the size of the vehicle and unprecedented acoustics, NASA conducted an extensive assessment of options for testing, and as result, chose to augment the Space Power Facility at NASA Plum Brook Station, of the John H. Glenn Research Center to provide the needed test capabilities. The augmentation included designing and building the World s highest mass capable vibration table, the highest power large acoustic chamber, and adaptation of the existing World s largest thermal vacuum chamber as a reverberant electromagnetic interference test chamber. These augmentations were accomplished from 2007 through early 2011. Acceptance testing began in Spring 2011 and will be completed in the Fall of 2011. This paper provides an overview of the capabilities, design, construction and acceptance of this extraordinary facility.

  12. Streamer chamber: pion decay

    1992-01-01

    The real particles produced in the decay of a positive pion can be seen in this image from a streamer chamber. Streamer chambers consist of a gas chamber through which a strong pulsed electric field is passed, creating sparks as a charged particle passes through it. A magnetic field is added to cause the decay products to follow curved paths so that their charge and momentum can be measured.

  13. High-voltage spark atomic emission detector for gas chromatography

    Calkin, C. L.; Koeplin, S. M.; Crouch, S. R.

    1982-01-01

    A dc-powered, double-gap, miniature nanosecond spark source for emission spectrochemical analysis of gas chromatographic effluents is described. The spark is formed between two thoriated tungsten electrodes by the discharge of a coaxial capacitor. The spark detector is coupled to the gas chromatograph by a heated transfer line. The gas chromatographic effluent is introduced into the heated spark chamber where atomization and excitation of the effluent occurs upon breakdown of the analytical gap. A microcomputer-controlled data acquisition system allows the implementation of time-resolution techniques to distinguish between the analyte emission and the background continuum produced by the spark discharge. Multiple sparks are computer averaged to improve the signal-to-noise ratio. The application of the spark detector for element-selective detection of metals and nonmetals is reported.

  14. Laser spark distribution and ignition system

    Woodruff, Steven; McIntyre, Dustin L.

    2008-09-02

    A laser spark distribution and ignition system that reduces the high power optical requirements for use in a laser ignition and distribution system allowing for the use of optical fibers for delivering the low peak energy pumping pulses to a laser amplifier or laser oscillator. An optical distributor distributes and delivers optical pumping energy from an optical pumping source to multiple combustion chambers incorporating laser oscillators or laser amplifiers for inducing a laser spark within a combustion chamber. The optical distributor preferably includes a single rotating mirror or lens which deflects the optical pumping energy from the axis of rotation and into a plurality of distinct optical fibers each connected to a respective laser media or amplifier coupled to an associated combustion chamber. The laser spark generators preferably produce a high peak power laser spark, from a single low power pulse. The laser spark distribution and ignition system has application in natural gas fueled reciprocating engines, turbine combustors, explosives and laser induced breakdown spectroscopy diagnostic sensors.

  15. An Evaluation of the Additional Acoustic Power Needed to Overcome the Effects of a Test-Articles Absorption During Reverberant Chamber Acoustic Testing of Spaceflight Hardware

    Hozman, Aron D.; Hughes, William O.

    2014-01-01

    It is important to realize that some test-articles may have significant sound absorption that may challenge the acoustic power capabilities of a test facility. Therefore, to mitigate this risk of not being able to meet the customers target spectrum, it is prudent to demonstrate early-on an increased acoustic power capability which compensates for this test-article absorption. This paper describes a concise method to reduce this risk when testing aerospace test-articles which have significant absorption. This method was successfully applied during the SpaceX Falcon 9 Payload Fairing acoustic test program at the NASA Glenn Research Center Plum Brook Stations RATF.

  16. Rotating arc spark plug

    Whealton, John H.; Tsai, Chin-Chi

    2003-05-27

    A spark plug device includes a structure for modification of an arc, the modification including arc rotation. The spark plug can be used in a combustion engine to reduce emissions and/or improve fuel economy. A method for operating a spark plug and a combustion engine having the spark plug device includes the step of modifying an arc, the modifying including rotating the arc.

  17. Acoustic Igniter Project

    National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...

  18. Reconstruction of data in low-mass magnetostrictive chambers

    The reconstruction of spark positions in a set of low-mass spark chambers with remote magnetostrictive readout, used in a study of the reaction π-p → K0 Λ, is described. The main detectors used were optical spark chambers but in order to provide information close to the vertices low-mass magnetostrictive chambers were fitted inside the cone of the superconducting polarised target magnet. (U.K.)

  19. Acoustics

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  20. An experimental investigation of a lean-burn natural-gas pre-chamber spark ignition engine for cogeneration; Swiss Motor. Modification d'un moteur diesel pour le fonctionnement au gaz naturel en cogeneration. Fonctionnement avec prechambre de combustion

    Roethlisberger, R.; Favrat, D.

    2001-07-01

    This thesis presented at the Department of Mechanical Engineering of the Swiss Federal Institute of Technology in Lausanne describes the conversion and testing of a commercial diesel engine for use as a lean-burn, natural gas, pre-chamber, spark ignition engine with a rated power of 150 kW, in combined heat and power (CHP) plants. The objective of the investigations - to evaluate the potential of reducing exhaust gas emissions - is discussed in detail with respect to NO{sub x} and CO emissions. The approach adopted includes both experimental work and numerical simulation. The report describes the testing facilities used. The results obtained with experimental spark-plug configurations based on simulation results are presented and the influence of various pre-chamber configuration variants are discussed. The results of the tests are presented and the significant reduction of NO{sub x}, CO and unburned-hydrocarbon (THC) emissions are discussed. The authors state that the engine, which achieves a fuel efficiency of more than 36.5%, fulfils the Swiss requirements on exhaust gas emissions. Also, ways of compensating for the slight loss in fuel-conversion efficiency in the pre-chamber configuration are discussed.

  1. Fastdata processing with Spark

    Karau, Holden

    2013-01-01

    This book will be a basic, step-by-step tutorial, which will help readers take advantage of all that Spark has to offer.Fastdata Processing with Spark is for software developers who want to learn how to write distributed programs with Spark. It will help developers who have had problems that were too much to be dealt with on a single computer. No previous experience with distributed programming is necessary. This book assumes knowledge of either Java, Scala, or Python.

  2. An acoustically driven microliter flow chamber on a chip (muFCC) for cell-cell and cell-surface interaction studies.

    Schneider, Matthias F; Guttenberg, Zeno; Schneider, Stefan W; Sritharan, Kumudesh; Myles, Vanessa M; Pamukci, Umut; Wixforth, Achim

    2008-03-14

    A novel method for pumping very small volumes of liquid by using surface acoustic waves is employed to create a microfluidic flow chamber on a chip. It holds a volume of only a few mul and its planar design provides complete architectural freedom. This allows for the reconstruction of even complex flow scenarios (e.g. curvatures, bifurcations and stenosis). Addition of polymer walls to the planar fluidic track enables cell culturing on the chip surface and the investigation of cell-cell adhesion dynamics under flow. We demonstrate the flexibility of the system for application in many areas of microfluidic investigations including blood clotting phenomena under various flow conditions and the investigation of different stages of cell adhesion. PMID:18306189

  3. Spark-integrated propellant injector head with flashback barrier

    Mungas, Gregory Stuart (Inventor); Fisher, David James (Inventor); Mungas, Christopher (Inventor)

    2012-01-01

    High performance propellants flow through specialized mechanical hardware that allows for effective and safe thermal decomposition and/or combustion of the propellants. By integrating a sintered metal component between a propellant feed source and the combustion chamber, an effective and reliable fuel injector head may be implemented. Additionally the fuel injector head design integrates a spark ignition mechanism that withstands extremely hot running conditions without noticeable spark mechanism degradation.

  4. SPARK GAP SWITCH

    Neal, R.B.

    1957-12-17

    An improved triggered spark gap switch is described, capable of precisely controllable firing time while switching very large amounts of power. The invention in general comprises three electrodes adjustably spaced and adapted to have a large potential impressed between the outer electrodes. The central electrode includes two separate elements electrically connected togetaer and spaced apart to define a pair of spark gaps between the end electrodes. Means are provided to cause the gas flow in the switch to pass towards the central electrode, through a passage in each separate element, and out an exit disposed between the two separate central electrode elements in order to withdraw ions from the spark gap.

  5. SparkJet Efficiency

    Golbabaei-Asl, Mona; Knight, Doyle; Anderson, Kellie; Wilkinson, Stephen

    2013-01-01

    A novel method for determining the thermal efficiency of the SparkJet is proposed. A SparkJet is attached to the end of a pendulum. The motion of the pendulum subsequent to a single spark discharge is measured using a laser displacement sensor. The measured displacement vs time is compared with the predictions of a theoretical perfect gas model to estimate the fraction of the spark discharge energy which results in heating the gas (i.e., increasing the translational-rotational temperature). The results from multiple runs for different capacitances of c = 3, 5, 10, 20, and 40 micro-F show that the thermal efficiency decreases with higher capacitive discharges.

  6. Contribution to the study of an lpg jet in the combustion chamber of a spark-ignition engine; Contribution a l'etude d'un jet de gpl dans la chambre de combustion d'un moteur a allumage commande, pour differentes strategies d'injection

    Duong Viet, D.

    2002-07-01

    It appears tempting to combine the less polluting combustion of LPG with the energy performances of a direct injection spark-ignition engine. To this aim the study of high pressure injection of a liquid LPG jet, directly inside the combustion chamber of an engine was performed in two ways: Experimental studies: one with fast cinematography and another with the method of Doppler phases in an one-cylinder 'transparent' engine for various conditions of injection and without combustion. They respectively deliver empirical laws for the jet development and some informations about size and speed of the droplets of LPG. A modeling of the jet could then be made on the basis of a turbulent and deviated jet the parameters of which could be adjusted using results of the preceding experimental study. (author)

  7. Testing of the J-2X Augmented Spark Igniter (ASI) and Its Electronics

    Osborne, Robin

    2015-01-01

    Reliable operation of the spark ignition system electronics in the J-2X Augmented Spark Igniter (ASI) is imperative in assuring ASI ignition and subsequent Main Combustion Chamber (MCC) ignition events are reliable in the J-2X Engine. Similar to the man-rated J-2 and RS-25 engines, the J-2X ignition system electronics are equipped with spark monitor outputs intended to indicate that the spark igniters are properly energized and sparking. To better understand anomalous spark monitor data collected on the J-2X development engines at NASA Stennis Space Center (SSC), a comprehensive subsystem study of the engine's low- and high-tension spark ignition system electronics was conducted at NASA Marshall Space Flight Center (MSFC). Spark monitor output data were compared to more detailed spark diagnostics to determine if the spark monitor was an accurate indication of actual sparking events. In addition, ignition system electronics data were closely scrutinized for any indication of an electrical discharge in some location other than the firing tip of the spark igniter - a problem not uncommon in the development of high voltage ignition systems.

  8. A focused electric spark source for non-contact stress wave excitation in solids.

    Dai, Xiaowei; Zhu, Jinying; Haberman, Michael R

    2013-12-01

    A focused electric spark is used as a non-contact acoustic source to excite stress waves in solids. The source consists of an electric spark source located at the near focus of an ellipsoidal reflector that focuses the acoustic disturbance generated by the spark source to the far focal point. Experimental studies using both contact and non-contact sensors indicate that the source has the capability to excite the Rayleigh surface wave and impact-echo mode (S1-zero-group-velocity Lamb mode) in a 250 mm thick concrete slab and to enable fully air-coupled testing of concrete specimens. PMID:25669297

  9. Fostering the Curiosity Spark

    Crow, Sherry R.

    2010-01-01

    Many of the children in the early grades who marveled at the plethora of beautiful resources just did not seem that interested by the time they reached upper elementary school. While some children sustained their spark of curiosity, others did not. The force that keeps children (or people of any age) excited about anything is called "intrinsic…

  10. QQ对决SPARK

    胡军梅

    2004-01-01

    “你想招摇过市、吸引注意力吗?有两种办法:一是脱了衣服奔跑,二是开QQ和SPARK。”网络上的小贴子,彰显了这两款时尚小车对消费者的巨大吸引力。从2003年4月上海国际汽车展开始,微车市场风云突起:奇瑞QQ(以下简称QQ)和上海通用五铃SPARK(以下简称SPARK)展开激烈竞争。狭路相逢,到底谁更胜一筹呢?

  11. Brookhaven National Laboratory's multiparticle spectrometer drift chamber system

    A system of drift chambers is being built to replace the present spark chambers in the Brookhaven National Laboratory's Multiparticle Spectrometer. This system will handle a beam of approx. 3 million particles per second and have a resolution of 200 μm. A summary of the status of the chambers and the custom integrated circuits is presented. The data acquisition system is described. Prototype chambers have been built and tested with results that are consistent with the expected chamber properties

  12. Fast data processing with Spark

    Sankar, Krishna

    2015-01-01

    Fast Data Processing with Spark - Second Edition is for software developers who want to learn how to write distributed programs with Spark. It will help developers who have had problems that were too big to be dealt with on a single computer. No previous experience with distributed programming is necessary. This book assumes knowledge of either Java, Scala, or Python.

  13. The Effect of Spark Timing on the Spark Ignition

    Rafeq A. Khalefa

    2013-04-01

    Full Text Available  In this work the effect of spark timing on the spark ignition engines is investigated by computer simulation and experimental test for speeds of (1500,2000,2500,3000 and 3500rpm at spark timing of (20o,30o,40o,50o and 60o before TDC for each speed. This is done in order to find a suitable  mathematical expression for spark ignition advancing with respect to the speed of the engine to predict the correct ignition advance  as in real engines .The results showed that the method of using a mathematical expression is more realistic and reasonable  comparing  with the results obtained by other workers. 

  14. SPARK Version One: reference manual

    SPARK is a library of FORTRAN computer codes which is used to analyze electrical eddy-current distributions. Version One of SPARK is designed to calculate eddy currents flowing on conducting surfaces where current flow is assumed zero in the direction normal to the surface. Surfaces may vary in resistivity and/or thickness and may include holes. Version One can find a transient solution series in time, a purely resistive solution, or a purely inductive solution. A principal feature of SPARK is the calculation of forces, which result from the interaction of the eddy currents with the primary magnetic field, in a form which is compatible with existing structural analysis codes

  15. Golden Jubilee photos: The first CERN bubble chamber

    2004-01-01

    In the 1950s and 1960s, bubble and spark chambers were the dominant experimental tools in high-energy physics. While spark chambers were usually built and fitted to specific experiments, bubble chambers were constructed as general purpose devices that could be used for a variety of experiments. At CERN, the bubble chamber programme started under Charles Peyrou in the late 1950s. The first of CERN's bubble chambers, a 30 cm hydrogen chamber, is seen here being inserted into its vacuum tank. The HBC30, as it was called, took its first beam from the SC in 1959. One of the first pictures taken, of a positive pion-proton interaction, began a long series of pretty images for which bubble chambers would become famous. When it stopped operating in spring 1962, the HBC30 had consumed 150 km of film in its 3 years of operation.

  16. Differences in acoustic target strength pattern between fish with one- and two-chambered swimbladder during rotation in the horizontal plane

    Frouzová, Jaroslava; Kubečka, Jan; Mrkvička, Tomáš

    2011-01-01

    Roč. 109, č. 1 (2011), s. 114-118. ISSN 0165-7836 R&D Projects: GA ČR(CZ) GA206/07/1392 Institutional research plan: CEZ:AV0Z60170517 Keywords : target strength * fish * swimbladder * horizontal * acoustics Subject RIV: EH - Ecology, Behaviour Impact factor: 1.586, year: 2011

  17. Design of a Fully Anechoic Chamber

    Rusz, Roman

    2015-01-01

    This thesis deals with fully anechoic chamber design. The main aim of this thesis is to design fully anechoic chamber according to acoustics laws and customers (Honeywell’s) requirements. The fully anechoic chamber will be used for measuring sound and vibration quantities. This work is divided into two main parts. The first part deals with the general anechoic chamber theory and all its related design aspects. The second part, practical part, focus on specific design according to requirements...

  18. Efficiency of SparkJet

    Golbabaei-Asl, M.; Knight, D.; Wilkinson, S.

    2013-01-01

    The thermal efficiency of a SparkJet is evaluated by measuring the impulse response of a pendulum subject to a single spark discharge. The SparkJet is attached to the end of a pendulum. A laser displacement sensor is used to measure the displacement of the pendulum upon discharge. The pendulum motion is a function of the fraction of the discharge energy that is channeled into the heating of the gas (i.e., increasing the translational-rotational temperature). A theoretical perfect gas model is used to estimate the portion of the energy from the heated gas that results in equivalent pendulum displacement as in the experiment. The earlier results from multiple runs for different capacitances of C = 3, 5, 10, 20, and 40(micro)F demonstrate that the thermal efficiency decreases with higher capacitive discharges.1 In the current paper, results from additional run cases have been included and confirm the previous results

  19. Are Crab nanoshots Schwinger sparks?

    Stebbins, Albert [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Yoo, Hojin [Univ. of Wisconsin, Madison, WI (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)

    2015-05-21

    The highest brightness temperature ever observed are from "nanoshots" from the Crab pulsar which we argue could be the signature of bursts of vacuum e± pair production. If so this would be the first time the astronomical Schwinger effect has been observed. These "Schwinger sparks" would be an intermittent but extremely powerful, ~103 L, 10 PeV e± accelerator in the heart of the Crab. These nanosecond duration sparks are generated in a volume less than 1 m3 and the existence of such sparks has implications for the small scale structure of the magnetic field of young pulsars such as the Crab. As a result, this mechanism may also play a role in producing other enigmatic bright short radio transients such as fast radio bursts.

  20. Are Crab Nanoshots Schwinger Sparks?

    Stebbins, Albert

    2015-01-01

    The highest brightness temperature ever observed are from "nanoshots" from the Crab pulsar which we argue could be the signature of bursts of vacuum $e^{\\pm}$ pair production. If so this would be the first time the astronomical Schwinger effect has been observed. These "Schwinger sparks" would be an intermittent but extremely powerful, $\\sim 10^3 L_{\\astrosun}$, 10 PeV $e^{\\pm}$ accelerator in the heart of the Crab. These nanosecond duration sparks are generated in a volume less than $1 m^3$ and the existence of such sparks has implications for the small scale structure of the magnetic field of young pulsars such as the Crab. This mechanism may also play a role in producing other enigmatic bright short radio transients such as fast radio bursts.

  1. Bright Sparks of Our Future!

    Riordan, Naoimh

    2016-04-01

    My name is Naoimh Riordan and I am the Vice Principal of Rockboro Primary School in Cork City, South of Ireland. I am a full time class primary teacher and I teach 4th class, my students are aged between 9-10 years. My passion for education has developed over the years and grown towards STEM (Science, Technology, Engineering and Mathematics) subjects. I believe these subjects are the way forward for our future. My passion and beliefs are driven by the unique after school programme that I have developed. It is titled "Sparks" coming from the term Bright Sparks. "Sparks" is an after school programme with a difference where the STEM subjects are concentrated on through lessons such as Science, Veterinary Science Computer Animation /Coding, Eco engineering, Robotics, Magical Maths, Chess and Creative Writing. All these subjects are taught through activity based learning and are one-hour long each week for a ten-week term. "Sparks" is fully inclusive and non-selective which gives all students of any level of ability an opportunity to engage into these subjects. "Sparks" is open to all primary students in County Cork. The "Sparks" after school programme is taught by tutors from the different Universities and Colleges in Cork City. It works very well because the tutor brings their knowledge, skills and specialised equipment from their respective universities and in turn the tutor gains invaluable teaching practise, can trial a pilot programme in a chosen STEM subject and gain an insight into what works in the physical classroom.

  2. Water spark gap for a nitrogen laser

    Satisfactory operation of the Blumlein type nitrogen laser was obtained by using a water-filled spark gap. The water-filled spark gap uses flowing water, and the Blumlein circuit is charged by a Marx-bank driver

  3. Fiber laser coupled optical spark delivery system

    Yalin, Azer; Willson, Bryan; Defoort, Morgan; Joshi, Sachin; Reynolds, Adam

    2008-03-04

    A spark delivery system for generating a spark using a laser beam is provided, and includes a laser light source and a laser delivery assembly. The laser delivery assembly includes a hollow fiber and a launch assembly comprising launch focusing optics to input the laser beam in the hollow fiber. The laser delivery assembly further includes exit focusing optics that demagnify an exit beam of laser light from the hollow fiber, thereby increasing the intensity of the laser beam and creating a spark. Other embodiments use a fiber laser to generate a spark. Embodiments of the present invention may be used to create a spark in an engine. Yet other embodiments include collecting light from the spark or a flame resulting from the spark and conveying the light for diagnostics. Methods of using the spark delivery systems and diagnostic systems are provided.

  4. Modeling of Transient Heat Flux in Spark Ignition Engine During Combustion and Comparisons with Experiment

    T. F. Yusaf; Sye Hoe; Fong; M.Z. Yusoff; Hussein, I.

    2005-01-01

    A quasi-one dimensional engine cycle simulation program was developed to predict the transient heat flux during combustion in a spark ignition engine. A two-zone heat release model was utilized to model the combustion process inside the combustion chamber. The fuel, air and burned gas properties throughout the engine cycle were calculated using variable specific heats. The transient heat flux inside the combustion chamber due to the change in the in-cylinder gas temperature and pressure durin...

  5. Ussing Chamber

    Westerhout, J.; Wortelboer, H.; Verhoeckx, K.

    2015-01-01

    The Ussing chamber system is named after the Danish zoologist Hans Ussing, who invented the device in the 1950s to measure the short-circuit current as an indicator of net ion transport taking place across frog skin (Ussing and Zerahn, Acta Physiol Scand 23:110-127, 1951). Ussing chambers are increa

  6. Combustion of CNG in Charged Spark Ignition Engines

    Mitianiec, Wladyslaw

    2009-12-01

    The paper describes mixing of injected CNG with air and combustion process in spark ignition internal combustion engine. Because of higher ignition temperature of CNG the SI engines have more effective ignition system than conventional engines. The gas motion, turbulence, charge temperature and obviously electrical energy of the ignition coil have a big influence on the ignition and burning process in the combustion chamber. The paper includes theoretical and experimental investigations of ignition process in the high charged SI engines with direct CNG injection by using LES technique in KIVA program. Simulation of CNG combustion in the caloric chamber was carried in the environment of OpenFOAM program with LES model and also the experimental test was carried out for comparison of results in the chamber with the same geometry. The influence of the "tumble" and "swirl" on the sparking is shown by modelling of this process in premixed charge by using LES technique. The charge motion and also considerably turbulence effect influence strongly on the ignition process.

  7. Fiber coupled optical spark delivery system

    Yalin, Azer; Willson, Bryan; Defoort, Morgan

    2008-08-12

    A spark delivery system for generating a spark using a laser beam is provided, the spark delivery system including a laser light source and a laser delivery assembly. The laser delivery assembly includes a hollow fiber and a launch assembly comprising launch focusing optics to input the laser beam in the hollow fiber. In addition, the laser delivery assembly includes exit focusing optics that demagnify an exit beam of laser light from the hollow fiber, thereby increasing the intensity of the laser beam and creating a spark. In accordance with embodiments of the present invention, the assembly may be used to create a spark in a combustion engine. In accordance with other embodiments of the present invention, a method of using the spark delivery system is provided. In addition, a method of choosing an appropriate fiber for creating a spark using a laser beam is also presented.

  8. Wire Chamber

    1986-01-01

    Two wire chambers made originally for the R807 Experiment at CERN's Intersecting Storage Rings. In 1986 they were used for the PS 201 experiment (Obelix Experiment) at LEAR, the Low Energy Antiproton Ring. The group of researchers from Turin, using the chambers at that time, changed the acquisition system using for the first time 8 bit (10 bit non linear) analog to digital conversion for incoming signals from the chambers. The acquisition system was controlled by 54 CPU and 80 digital signal processors. The power required for all the electronics was 40 kW. For the period, this system was one of the most powerful on-line apparatus in the world. The Obelix Experiment was closed in 1996. To find more about how a wire chamber works, see the description for object CERN-OBJ-DE-038.

  9. Vacuum chamber

    A detailed description is given of the vacuum chamber of the so-called experimental equipment DEMAS (double-arm-time-of-flight spectrometer) at the heavy ion accelerator U-400 at the JINR-Dubna. (author)

  10. Stable And Oscillating Acoustic Levitation

    Barmatz, Martin B.; Garrett, Steven L.

    1988-01-01

    Sample stability or instability determined by levitating frequency. Degree of oscillation of acoustically levitated object along axis of levitation chamber controlled by varying frequency of acoustic driver for axis above or below frequency of corresponding chamber resonance. Stabilization/oscillation technique applied in normal Earth gravity, or in absence of gravity to bring object quickly to rest at nominal levitation position or make object oscillate in desired range about that position.

  11. Lifecycle of laser-produced air sparks

    We investigated the lifecycle of laser-generated air sparks or plasmas using multiple plasma diagnostic tools. The sparks were generated by focusing the fundamental radiation from an Nd:YAG laser in air, and studies included early and late time spark dynamics, decoupling of the shock wave from the plasma core, emission from the spark kernel, cold gas excitation by UV radiation, shock waves produced by the air spark, and the spark's final decay and turbulence formation. The shadowgraphic and self-emission images showed similar spark morphology at earlier and late times of its lifecycle; however, significant differences are seen in the midlife images. Spectroscopic studies in the visible region showed intense blackbody-type radiation at early times followed by clearly resolved ionic, atomic, and molecular emission. The detected spectrum at late times clearly contained emission from both CN and N2+. Additional spectral features have been identified at late times due to emission from O and N atoms, indicating some degree of molecular dissociation and excitation. Detailed spatially and temporally resolved emission analysis provides insight about various physical mechanisms leading to molecular and atomic emission by air sparks, including spark plasma excitation, heating of cold air by UV radiation emitted by the spark, and shock-heating

  12. A COMPARATIVE STUDY BETWEEN DTS-I ENGINE AND SINGLE SPARK IGNITION ENGINE

    Aditya Patwardhan *; Indraneel Ray; Dr. Dhananjay R. Dolas

    2016-01-01

    Today’s common trend is that people want strong performance and greater fuel efficiency but single spark ignition engines fail to satisfy these needs now-a-day’s complete combustion is not at all possible in automobiles due to various losses in combustion chamber and due various other design parameters. Thus the process of combustion is not at all instantaneous and therefore alternate solution to it is by burning the fuel as quickly as possible by using two spark plugs instead of ...

  13. wire chamber

    Was used in ISR (Intersecting Storage Ring) split field magnet experiment. Multi-wire detectors contain layers of positively and negatively charged wires enclosed in a chamber full of gas. A charged particle passing through the chamber knocks negatively charged electrons out of atoms in the gas, leaving behind positive ions. The electrons are pulled towards the positively charged wires. They collide with other atoms on the way, producing an avalanche of electrons and ions. The movement of these electrons and ions induces an electric pulse in the wires which is collected by fast electronics. The size of the pulse is proportional to the energy loss of the original particle.

  14. Sample preparations for spark source mass spectrography

    Methods have been developed for the preparation of various materials for spark source mass spectrography. The essential features of these preparations (all which can provide adequate precision in a cost-effective manner) consist in obtaining spark-stable electrode sample pieces, a common matrix, a reduction of anomolous effects in the spark, the incorporation of a suitable internal standard for plate response normalization, and a reduction in time

  15. Studies of particle interactions in bubble chamber, spark chambers and counter experiments. Annual progress report

    Holloway, L.E.; O' Halloran, T.A. Jr.; Simmons, R.O.

    1983-07-01

    During the past six years we have carried out and planned experiments which predominantly studied the production and decay of particles containing charmed quarks. A series of photoproduction and neutron production experiments started with the very early observation of the production of J/psi by neutrons and by photons at Fermilab. From subsequent experiments using these neutral beams and the basic detecting system, we have reported results on the photoproduction of the ..lambda../sub c/ charmed baryon and the D and D* charmed mesons. More recent runs are studying the high energy photoproduction of vector mesons including the psi'. The present experiment in this sequence is using neutrons to produce a large number of D mesons. Another series of experiments at Fermilab set out to study the hadronic production of charmed mesons. The Chicago Cyclotron facility was modified with a detector sensitive to various possible production mechanisms. The experiments were a success; clean signals of D mesons were observed to be produced by pions, and also the production of chi/sub c/ with the subsequent decay via a ..gamma..-ray to psi was observed. The charmonium experiments run this year have better photon resolution for measuring the decays of chi/sub c/ to psi. We are part of a collaboration which is working on the Collider Detector Facility for Fermilab. The CDF at Fermilab is a possible source of (weak) intermediate vector bosons from the collisions of protons and anti-protons. Our responsibilities in the CDF include both the construction of the muon detector and the designing, planning, and testing of the FASTBUS electronics. The second part of our weak interaction program is the Neutrino Oscillation experiment which is now under construction at Brookhaven.

  16. SES and Acoustics at GSFC

    Hogue, Patrick

    2008-01-01

    This paper presents air and surface cleanliness characterization of the acoustics test facility and large (SES) thermal vacuum chamber at Goddard Space flight Center in Greenbelt, MD during the New Horizons Pluto probe program. It is shown that slow back-fill of the SES chamber is necessary to prevent excessive particle redistribution.

  17. Robert Chambers

    K. Biekart (Kees); D.R. Gasper (Des)

    2013-01-01

    textabstractProfessor Robert Chambers is a Research Associate at the Institute of Development Studies (IDS), University of Sussex (Brighton, UK), where he has been based for the last 40 years, including as Professorial Research Fellow. He became involved in the field of development management in the

  18. Storytelling through animation: Oxford Sparks

    Pyle, D. M.; Cook, A.

    2013-12-01

    Oxford Sparks is a portal that launched in 2012, with the aim of bringing together resources that have been created across the University of Oxford and elsewhere for the purpose of wider engagement with science. To bring attention to this site, Oxford Sparks developed a set of high-quality short animations, each designed to tell a story relating to a current area of science. These animations have been launched on YouTube, and will shortly be available on iTunesU, and have covered broad areas of science from subduction zones (';Underwater Volcano Disaster'), through the early history of the solar system (';Rogue Planet') to the workings of the Large Hadron Collider (';A quick look around the LHC'). The animations have each been developed in close collaboration with researchers, created by a team with experience of education, engagement and outreach. The two minute scripts are intended to be both widely accessible and viewable as ';stand alone' stories. To this end, the scripts are humorous; while the animations are delightfully quirky, and created by professional animator with a degree-level science background. The animations are also intended to be used as ';lesson starters' in school, and educational activities graded for different age groups are being developed in parallel with the animations. They have been used, successfully, on pre-university summer schools, and in university classes. We are gathering both quantitative (analytics) and qualitative (school teacher and student focus group) feedback to monitor the success of the project, and to understand the strengths and weaknesses of the approach. In the first year since launch, Oxford Sparks animations were viewed over 80,000 times on YouTube, in part due to the surge of interest in the Large Hadron Collider animation after the discovery of the Higgs Boson.

  19. Liquid hydrogen bubble chamber (diam. 30 cm), seen here being inserted into its vacuum tank

    1959-01-01

    In the 1950s and 1960s, bubble and spark chambers were the dominant experimental tools in high-energy physics. While spark chambers were usually built and fitted to specific experiments, bubble chambers were constructed as general purpose devices that could be used for a variety of experiments. At CERN, the bubble chamber programme started under Charles Peyrou in the late 1950s. The first of CERN's bubble chambers, a 30 cm hydrogen chamber, is seen here being inserted into its vacuum tank. The HBC30, as it was called, took its first beam from the SC in 1959. One of the first pictures taken, of a positive pion-proton interaction, began a long series of pretty images for which bubble chambers would become famous. When it stopped operating in spring 1962, the HBC30 had consumed 150 km of film in its 3 years of operation.

  20. Sparks.

    Education Unlimited, 1979

    1979-01-01

    Described are: a banking token economy to increase math skills of learning-disabled and emotionally disturbed boys (11 to 14 years old); task analysis approach to individualizing instruction for mainstreamed learning-disabled students; language and reading instruction for mainstreamed deaf and hearing-impaired students; and a music program for…

  1. Programmable spark counter of tracks

    For the purpose, a new set-the programmable all-automatic spark counter AIST-4-has been developed and manufactured. Compared to our previous automated spark counter ISTRA, which was operated by the integrated fixed program, the new set is operated completely by a personal computer. The mechanism for pressing and pulling the aluminized foil is put into action by a step motor operated by a microcontroller. The step motor turns an axle. The axle has two eccentrics. One of them moves a pressing plate up and down. The second eccentric moves the aluminized foil by steps of ∼15mm after the end of each pulse counting. One turnover of the axle corresponds to one pulse count cycle. The step motor, the high-voltage block and the pulse count block are operated by the microcontroller PIC 16C84 (Microstar). The set can be operated either manually by keys on the front panel or by a PC using dialogue windows for radon or neutron measurements (for counting of alpha or fission fragment tracks). A number of algorithms are developed: the general procedures, the automatic stopping of the pulse counting, the calibration curve, determination of the count characteristics and elimination of the short circuit in a track

  2. Systematic design of acoustic devices by topology optimization

    Jensen, Jakob Søndergaard; Sigmund, Ole

    2005-01-01

    We present a method to design acoustic devices with topology optimization. The general algorithm is exemplified by the design of a reflection chamber that minimizes the transmission of acoustic waves in a specified frequency range....

  3. Ionization chamber

    An ionization chamber X-ray detector is described. It comprises a flat cathode sheet parallel to an anode which has a perforated insulating layer on its surface. An open grid, a thin perforated metal sheet is disposed on the insulating layer - the perforations of the layer and sheet are aligned. There is a detector gas and means for maintaining the grid at an electric potential between that of the anode and cathode and for measuring the current flow from the anode to the cathode. The grid shields the anode from the electric field produced by the positive ions which flow towards the cathode and this permits an independent measurement of the electron current flowing to the anode; even when the X-ray pulse length is not much shorter than the ion drift time. The recovery time of the ionization chamber is thus decreased by several orders of magnitude over previous chambers. The grid will normally be fixed to the anode and by shielding the anode from the cathode electric field, tends to eliminate capacitive microphone currents which would otherwise flow in the anode circuit. (U.K.)

  4. Nondestructive Inspection of Ceramic Spark Plug Parts Using Nonlinear Elastic Wave Spectroscopy

    Krofta, Josef; Převorovský, Zdeněk; Sladký, P.

    Praha : Institute of Thermomechanics AS CR, v.v.i, 2011 - (Převorovský, Z.; Fárová, Z.). s. 26 ISBN 978-80-87012-34-5. [International Conference on Nonlinear Elasticity in Materials /16./. 05.06.2011-11.06.2011, Praha] Institutional research plan: CEZ:AV0Z20760514 Keywords : total harmonic distortion * spark plug pramic insulater * nonlinear elastic wave Subject RIV: BI - Acoustics

  5. THE EFFECT OF COMPRESSION RATIO VARIATIONS ON THE ENGINE PERFORMANCE PARAMETRES IN SPARK IGNITION ENGINES

    Yakup SEKMEN

    2005-01-01

    Full Text Available Performance of the spark ignition engines may be increased by changing the geometrical compression ratio according to the amount of charging in cylinders. The designed geometrical compression ratio can be realized as an effective compression ratio under the full load and full open throttle conditions since the effective compression ratio changes with the amount of charging into the cylinder in spark ignition engines. So, this condition of the spark ignition engines forces designers to change their geometrical compression ratio according to the amount of charging into the cylinder for improvement of performance and fuel economy. In order to improve the combustion efficiency, fuel economy, power output, exhaust emissions at partial loads, compression ratio must be increased; but, under high load and low speed conditions to prevent probable knock and hard running the compression ratio must be decreased gradually. In this paper, relation of the performance parameters to compression ratio such as power, torque, specific fuel consumption, cylindir pressure, exhaust gas temperature, combustion chamber surface area/volume ratio, thermal efficiency, spark timing etc. in spark ignition engines have been investigated and using of engines with variable compression ratio is suggested to fuel economy and more clear environment.

  6. Effect of Perforated Plates on the Acoustics of Annular Combustors

    Gullaud, Elsa; Nicoud, Franck

    2012-01-01

    This paper aims to show the influence of perforated plates on the acoustic modes in aeronautical gas turbine combustion chambers. The analytical model was implemented in a three-dimensional acoustic Helmholtz solver to account for the effect of perforated plates. First, an analytic test case is used to validate the coding in the acoustic solver. Then, a computation of the acoustic modes in an actual industrial chamber is conducted, taking into account the perforated liners. For both cases, a ...

  7. Characterization of spark-generated N-waves in air using an optical schlieren method.

    Karzova, Maria M; Yuldashev, Petr V; Khokhlova, Vera A; Ollivier, Sébastien; Salze, Edouard; Blanc-Benon, Philippe

    2015-06-01

    Accurate measurement of high-amplitude, broadband shock pulses in air is an important part of laboratory-scale experiments in atmospheric acoustics. Although various methods have been developed, specific drawbacks still exist and need to be addressed. Here, a schlieren optical method was used to reconstruct the pressure signatures of nonlinear spherically diverging short acoustic pulses generated using an electric spark source (2.5 kPa, 33 μs at 10 cm from the source) in homogeneous air. A high-speed camera was used to capture light rays deflected by refractive index inhomogeneities, caused by the acoustic wave. Pressure waveforms were reconstructed from the light intensity patterns in the recorded images using an Abel-type inversion method. Absolute pressure levels were determined by analyzing at different propagation distances the duration of the compression phase of pulses, which changed due to nonlinear propagation effects. Numerical modeling base on the generalized Burgers equation was used to evaluate the smearing of the waveform caused by finite exposure time of the high-speed camera and corresponding limitations in resolution of the schlieren technique. The proposed method allows the study of the evolution of spark-generated shock waves in air starting from the very short distances from the spark, 30 mm, up to 600 mm. PMID:26093414

  8. AROMA-AIRWICK: a CHLOE/CDC-3600 system for the automatic identification of spark images and their association into tracks

    The AROMA-AIRWICK System for CHLOE, an automatic film scanning equipment built at Argonne by Donald Hodges, and the CDC-3600 computer is a system for the automatic identification of spark images and their association into tracks. AROMA-AIRWICK has been an outgrowth of the generally recognized need for the automatic processing of high energy physics data and the fact that the Argonne National Laboratory has been a center of serious spark chamber development in recent years

  9. AROMA-AIRWICK: a CHLOE/CDC-3600 system for the automatic identification of spark images and their association into tracks

    Clark, R K

    1980-06-26

    The AROMA-AIRWICK System for CHLOE, an automatic film scanning equipment built at Argonne by Donald Hodges, and the CDC-3600 computer is a system for the automatic identification of spark images and their association into tracks. AROMA-AIRWICK has been an outgrowth of the generally recognized need for the automatic processing of high energy physics data and the fact that the Argonne National Laboratory has been a center of serious spark chamber development in recent years.

  10. Automatic registration of fission fragment tracks with a spark gap counting system

    The theoretical aspects of fission track production in polycarbonate foils are briefly discussed. An automatic counting system for fission tracks based on a spark gap chamber is described. A linear response for low fission track density, typical of environmental and biological samples, was obtained with a 252Cf source using an electrode of 33.2 mm2. The system also functions with electrodes of larger and smaller areas without any major changes in the instrument. (author) 23 refs.; 6 figs

  11. Sparking rates measured on the CRITS RFQ

    During the test of the LEDA injector on the CRITS RFQ, an automatic data acquisition system has been implemented. The purpose was to measure the sparking rate of this CW RFQ. The RF level has some influences on vacuum, but there is no evidence of any reciprocal effect. The raw sparking rate is very difficult to interpret, since burst of sparks bias the statistics. A more convenient and useful interpretation is the number of sparking seconds. At the nominal field level (1.75 Kilp), the sparking-second rate is 0.5 per minute without beam. It strongly depends on the field, with a logarithmic law: 4.5 decade/Kilp. With beam, the sparking rate jumps to 3.0 per minute. As far as tested, it depends neither on the beam current (20 to 80 mA) nor on the field (1.5 to 1.7 Kilp tested). With sparking rates as measured here, one could not hope to build an RFQ that would be free of sparks over a several months continuous operation. Such a requirement, based on an extrapolation of the curves presented here, would lead to a maximal electric field much lower than the Kilpatrick value, an unreasonable requirement for a functional RFQ. A conclusion is that a sparkless RFQ is hopeless, even with a very carefully conditioned cavity. It will probably be necessary to deal with a few sparks per day, and the linac must be able to restart automatically after a short beam interruption

  12. Chamber transport

    OLSON,CRAIG L.

    2000-05-17

    Heavy ion beam transport through the containment chamber plays a crucial role in all heavy ion fusion (HIF) scenarios. Here, several parameters are used to characterize the operating space for HIF beams; transport modes are assessed in relation to evolving target/accelerator requirements; results of recent relevant experiments and simulations of HIF transport are summarized; and relevant instabilities are reviewed. All transport options still exist, including (1) vacuum ballistic transport, (2) neutralized ballistic transport, and (3) channel-like transport. Presently, the European HIF program favors vacuum ballistic transport, while the US HIF program favors neutralized ballistic transport with channel-like transport as an alternate approach. Further transport research is needed to clearly guide selection of the most attractive, integrated HIF system.

  13. Influence of Acoustic and Electromagnetic Actions on the Properties of Aqueous Nanoparticle Dispersions Used as Tempering Liquids for Dental Cement

    Azharonok, V. V.; Belous, N. Kh.; Rodtsevich, S. P.; Goncharik, S. V.; Chubrik, N. N.; Koshevar, V. D.; Lopat‧ko, K. G.; Aftandilyants, E. G.; Veklich, A. N.; Boretskii, V. F.; Orlovich, A. I.

    2016-06-01

    The authors have studied the physicochemical properties of aqueous dispersions containing carbon, silver, and iron nanoparticles which were produced by elastic-spark synthesis under the conditions of subaqueous spark discharge, and also the influence of preliminary acoustic and high-frequency electromagnetic action on them and the change in the functional indices of the glass-ionomer cement tempered by these dispersions.

  14. Chaotic Combustion in Spark Ignition Engines

    Wendeker, M.; Czarnigowski, J.; Litak, G.; Szabelski, K.

    2002-01-01

    We analyse the combustion process in a spark ignition engine using the experimental data of an internal pressure during the combustion process and show that the system can be driven to chaotic behaviour. Our conclusion is based on the observation of unperiodicity in the time series, suitable stroboscopic maps and a complex structure of a reconstructed strange attractor. This analysis can explain that in some circumstances the level of noise in spark ignition engines increases considerably due...

  15. Electro-spark deposition technology

    Johnson, R.N. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-12-01

    Electro-Spark Deposition (ESD) is a micro-welding process that uses short duration, high-current electrical pulses to deposit or alloy a consumable electrode material onto a metallic substrate. The ESD process was developed to produce coatings for use in severe environments where most other coatings fail. Because of the exceptional damage resistance of these coatings, and the versatility of the process to apply a wide variety of alloys, intermetallics, and cermets to metal surfaces, the ESD process has been designated critical to the life and economy of the advanced fossil energy systems as the higher temperatures and corrosive environments exceed the limits of known structural materials to accommodate the service conditions. Developments include producing iron aluminide-based coatings with triple the corrosion resistance of the best previous Fe{sub 3}Al coatings, coatings with refractory metal diffusion barriers and multi layer coatings for achieving functionally gradient properties between the substrate and the surface. A new development is the demonstration of advanced aluminide-based ESD coatings for erosion and wear applications. One of the most significant breakthroughs to occur in the last dozen years is the discovery of a process regime that yields an order of magnitude increase in deposition rates and achievable coating thicknesses. Achieving this regime has required the development of advanced ESD electronic capabilities. Development is now focused on further improvements in deposition rates, system reliability when operating at process extremes, and economic competitiveness.

  16. Simplified Rotation In Acoustic Levitation

    Barmatz, M. B.; Gaspar, M. S.; Trinh, E. H.

    1989-01-01

    New technique based on old discovery used to control orientation of object levitated acoustically in axisymmetric chamber. Method does not require expensive equipment like additional acoustic drivers of precisely adjustable amplitude, phase, and frequency. Reflecting object acts as second source of sound. If reflecting object large enough, close enough to levitated object, or focuses reflected sound sufficiently, Rayleigh torque exerted on levitated object by reflected sound controls orientation of object.

  17. The Effect of Resistance on Rocket Injector Acoustics

    Morgan, C. J.

    2015-01-01

    Combustion instability, where unsteady heat release couples with acoustic modes, has long been an area of concern in liquid rocket engines. Accurate modeling of the acoustic normal modes of the combustion chamber is important to understanding and preventing combustion instability. The injector resistance can have a significant influence on the chamber normal mode shape, and hence on the system stability.

  18. Shock wave generated by high-energy electric spark discharge

    Liu, Qingming; Zhang, Yunming

    2014-10-01

    Shock wave generated by electric spark discharge was studied experimentally and the shock wave energy was evaluated in this paper. A pressure measurement system was established to study the pressure field of the electric spark discharge process. A series of electric spark discharge experiments were carried out and the energy of the electric spark used in present study was in the range of 10 J, 100 J, and 1000 J, respectively. The shock wave energy released from the electric spark discharge process was calculated by using the overpressure values at different measurement points near the electric spark discharge center. The good consistency of shock wave energies calculated by pressure histories at different measuring points in the same electric spark discharge experiment illustrates the applicability of the weak shock wave theory in calculating the energy of shock wave induced by electric spark discharge process. The result showed that shock wave formed at the initial stage of electric spark discharge process, and the shock wave energy is only a little part of electric spark energy. From the analysis of the shock wave energy and electric spark energy, a good linear relationship between shock wave energy and electric spark energy was established, which make it possible to calculate shock wave energy by measuring characteristic parameters of electric spark discharge process instead of shock wave. So, the initiation energy of direct initiation of detonation can be determined easily by measuring the parameters of electric spark discharge process.

  19. Electro-spark deposition technology

    Johnson, R.N. [Pacific Northwest Lab., WA (United States)

    1996-08-01

    Electro-Spark Deposition (ESD) is a micro-welding process that uses short duration, high-current electrical pulses to deposit or alloy a consumable electrode material onto a metallic substrate. The ESD process was developed to produce coatings for use in severe environments where most other coatings fail. Because of the exceptional damage resistance of these coatings, and the versatility of the process to apply a wide variety of alloys, intermetallics, and cermets to metal surfaces, the ESD process has been designated as one of the enabling technologies for advanced energy systems. Developments include producing iron aluminide-based coatings with triple the corrosion resistance of the best previous Fe{sub 3}Al coatings, coatings with refractory metal diffusion barriers and multi layer coatings for achieving functionally gradient properties between the substrate and the surface. One of the most significant breakthroughs to occur in the last dozen years is the discovery of a process regime that promises an order of magnitude increase in deposition rates and achievable coating thicknesses. Since this regime borders on and exceeds the normal operating limits of existing ESD electronic equipment, development is in progress to produce equipment that can consistently and reliably achieve these conditions for a broad range of materials. Progress so far has resulted in a consistent 500% increase in deposition rates, and greater rates still are anticipated. Technology transfer activities are a significant portion of the ESD program effort. Notable successes now include the start-up of a new business to commercialize the ESD technology, the incorporation of the process into the operations of a major gas turbine manufacturer, major new applications in gas turbine blade and steam turbine blade protection and repair, and in military, medical, metal-working, and recreational equipment applications.

  20. Aerosol behaviour in an acoustic field

    The average size of an aerosol submitted to acoustic waves is increased. This results from coagulation of the finest particles on the largest ones. The mechanisms responsible for acoustic agglomeration are mentioned. An experimental apparatus was developed in order to control the evolution of aerosol distribution in an acoustic field. Important deposition on the walls of the agglomeration chamber was observed as a consequence of the acoustically induced turbulent flow. Finally, a dimensionless relationship was established between deposition rates and particle diameters as a function of experimental parameters (aeraulic and acoustic conditions, etc...)

  1. Directed Energy Anechoic Chamber

    Federal Laboratory Consortium — The Directed Energy Anechoic Chamber comprises a power anechoic chamber and one transverse electromagnetic cell for characterizing radiofrequency (RF) responses of...

  2. Spark - a modern approach for distributed analytics

    CERN. Geneva; , Prasanth

    2016-01-01

    The Hadoop ecosystem is the leading opensource platform for distributed storing and processing big data. It is a very popular system for implementing data warehouses and data lakes. Spark has also emerged to be one of the leading engines for data analytics. The Hadoop platform is available at CERN as a central service provided by the IT department. By attending the session, a participant will acquire knowledge of the essential concepts need to benefit from the parallel data processing offered by Spark framework. The session is structured around practical examples and tutorials. Main topics: Architecture overview - work distribution, concepts of a worker and a driver Computing concepts of transformations and actions Data processing APIs - RDD, DataFrame, and SparkSQL

  3. Generation of nanoparticles by spark discharge

    The production of nanoparticles by microsecond spark discharge evaporation in inert gas is studied systematically applying transmission electron microscopy, mobility analysis and BET surface area measurement. The method of spark discharge is of special interest, because it is continuous, clean, extremely flexible with respect to material, and scale-up is possible. The particle size distributions are narrow and the mean primary particle size can be controlled via the energy per spark. Separated, unagglomerated particles, 3-12 nm in size, or agglomerates can be obtained depending on the flow rate. The nanoparticulate mass produced is typically 5 g/kWh. A formula is given, which estimates the mass production rate via thermal conductivity, evaporation enthalpy and the boiling point of the material used. We showed that with gas purified at the spot, the method produced gold particles that were so clean that sintering of agglomerated particles occurred at room temperature. The influence of a number of parameters on the primary particle size and mass production rate was studied and qualitatively understood with a model of Lehtinen and Zachariah (J Aerosol Sci 33:357-368, 2002). Surprisingly high charging probabilities for one polarity were obtained. Spark generation is therefore of special interest for producing monodisperse aerosols or particles of uniform size via electrical mobility analysis. Qualitative observations in the present study include the phenomenon of material exchange between the electrodes by the spark, which opens the possibility of producing arbitrary mixtures of materials on a nanoscale. If spark generation of nanoparticles is performed in a standing or almost standing gas, an aerogel of a web-like structure forms between surfaces of different electrical potential.

  4. Chaotic combustion in spark ignition engines

    We analyse the combustion process in a spark ignition engine using the experimental data of an internal pressure during the combustion process and show that the system can be driven to chaotic behaviour. Our conclusion is based on the observation of unperiodicity in the time series, suitable stroboscopic maps and a complex structure of a reconstructed strange attractor. This analysis can explain that in some circumstances the level of noise in spark ignition engines increases considerably due to nonlinear dynamics of a combustion process

  5. Optical diagnostics integrated with laser spark delivery system

    Yalin, Azer; Willson, Bryan; Defoort, Morgan; Joshi, Sachin; Reynolds, Adam

    2008-09-02

    A spark delivery system for generating a spark using a laser beam is provided, and includes a laser light source and a laser delivery assembly. The laser delivery assembly includes a hollow fiber and a launch assembly comprising launch focusing optics to input the laser beam in the hollow fiber. The laser delivery assembly further includes exit focusing optics that demagnify an exit beam of laser light from the hollow fiber, thereby increasing the intensity of the laser beam and creating a spark. Other embodiments use a fiber laser to generate a spark. Embodiments of the present invention may be used to create a spark in an engine. Yet other embodiments include collecting light from the spark or a flame resulting from the spark and conveying the light for diagnostics. Methods of using the spark delivery systems and diagnostic systems are provided.

  6. Communication Acoustics

    Blauert, Jens

    Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....

  7. A simple analytical model to study and control azimuthal instabilities in annular combustion chambers

    Parmentier, Jean-François; Salas, Pablo; Wolf, Pierre; Staffelbach, Gabriel; Nicoud, Franck; Poinsot, Thierry

    2012-01-01

    This study describes a simple analytical method to compute the azimuthal modes appearing in annular combustion chambers and help analyzing experimental, acoustic and large eddy simulation (LES) data obtained in these combustion chambers. It is based on a one-dimensional zero Mach number formulation where N burners are connected to a single annular chamber. A manipulation of the corresponding acoustic equations in this configuration leads to a simple dispersion relation which can be solved by ...

  8. Acoustic Neuroma

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

  9. Acoustic Neuroma

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. The tumor ... press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the symptoms ...

  10. Modelling Spark Integration in Science Classroom

    Marie Paz E. Morales

    2014-02-01

    Full Text Available The study critically explored how a PASCO-designed technology (SPARK ScienceLearning System is meaningfully integrated into the teaching of selected topics in Earth and Environmental Science. It highlights on modelling the effectiveness of using the SPARK Learning System as a primary tool in learning science that leads to learning and achievement of the students. Data and observation gathered and correlation of the ability of the technology to develop high intrinsic motivation to student achievement were used to design framework on how to meaningfully integrate SPARK ScienceLearning System in teaching Earth and Environmental Science. Research instruments used in this study were adopted from standardized questionnaires available from literature. Achievement test and evaluation form were developed and validated for the purpose of deducing data needed for the study. Interviews were done to delve into the deeper thoughts and emotions of the respondents. Data from the interviews served to validate all numerical data culled from this study. Cross-case analysis of the data was done to reveal some recurring themes, problems and benefits derived by the students in using the SPARK Science Learning System to further establish its effectiveness in the curriculum as a forerunner to the shift towards the 21st Century Learning.

  11. Engineering alumnus John Sparks recognized for contributions

    Nystrom, Lynn A.

    2008-01-01

    Virginia Tech's College of Engineering presented its 2008 Distinguished Service Award to mechanical engineering alumnus John Sparks, director of engineering and technology programs at Aerojet, a GenCorp Inc. company, recognized as a major space and defense leader specializing in missile and space propulsion as well as defense and armaments.

  12. Reduction of the exhaust gas emissions during warm up by improving the mixture preparation of spark-ignition engines

    During warm-up the engine emits the highest concentration of exhaust gas emissions. An improvement of the atomization behaviour of the injected fuel should lead to a good mixture preparation in the manifold and combustion chamber and further to lower exhaust gas emissions during warm up. During these investigations it was found out that the build-up of fuel film in the manifold of cold spark-ignition engines can not be prevented. But by injecting the fuel at the open inlet valve it is possible to reduce the fuel film. The injection of extremely finely atomized fuel at the open inlet valve leads to a better mixture preparation with smaller fuel dropplets in the manifold and combustion chamber. This again leads, during warm-up of the spark ignition engine, to a reduction of the HC emissions of 30% and the CO emissions of 50%. (author)

  13. MOTIONS STUDY OF A SINGLE CYLINDER HIGH SPEED SPARK IGNITION LINIER ENGINE WITH SPRING SYSTEM AS RETURN CYCLE

    A. Z.M. Fathallah; Semin,; I. M. Ariana; I. Gerianto

    2014-01-01

    A single cylinder two stroke spark ignition conventional engine have been modified to linier engine with spring mechanism. Before develop the design of linear engine is necessary to analysis of motion. Although principle of combustion process in combustion chamber is the same in fact the oscillation movement is different. Simulation technique has been adopted to study both linear and conventional engine. 3D engines model have been simulate of the motion. Due to simulate both engines, three di...

  14. Intershield to tank sparks at the Daresbury tandem

    The causes of serious metallic melting and denting due to discharges in the insulating gas of the Daresbury tandem are examined. In order to explain the melting, high oscillating currents have to flow in the spark channels, and those can only be expected when return strokes excite local electromagnetic modes at the site of the origin of breakdown. In the case of intershield to tank sparks, evidence that magnetic confinement of the spark channel produces denting is presented. A model which accounts for the differences between sparks at Oak Ridge and sparks at Daresbury is also presented. (author)

  15. Numerical and experimental characterization of knock occurrence in a turbo-charged spark-ignition engine

    Highlights: • An index of knock intensity has been based on the cylinder pressure oscillations. • This index allows to set the knock limited spark at different engine operating points. • The influence of the transducer position on the measurement of the pressure oscillations is investigated. - Abstract: In this paper, knock intensity is deeply studied through experimental tests carried out on a turbo-charged spark-ignition engine. The experimental methodology is based on the analysis of the pressure signals detected within the engine combustion chamber. In order to evaluate knock intensity, fast Fourier transform (FFT) and bandpass filtering techniques have been used to process the cylinder pressure values acquired in five hundred consecutive cycles. Resonance frequencies have been found at about 8.0 kHz, 13.5 kHz and 18.5 kHz. The maximum amplitude of pressure oscillations (MAPO) has been calculated for every engine cycle. In order to discriminate between knocking cycles and free knock cycles, MAPO values are compared to threshold values. These values have been determined following a statistical approach described in the paper. An index of knock intensity, that takes into account both the extent of knocking events and the cycle- to-cycle variation has been introduced. Thus, at different engine operating points, the knock limited spark advance can be found. At the end, a numerical analysis of the combustion process has been carried out in order to find a relationship between the knock occurrence and the combustion chamber geometry. A 3-D computational model, based on AVL FIRE v2011 code, has been utilized. The 3-D model is able to predict the auto-ignition zones. By matching these zones and the map of mixture distribution, it is possible to predict the location of the most dangerous areas within the combustion chamber. Furthermore, comparisons of calculated and measured data provide sound information about the importance of pressure transducer position in

  16. Acoustic transducer apparatus with reduced thermal conduction

    Lierke, Ernst G. (Inventor); Leung, Emily W. (Inventor); Bhat, Balakrishna T. (Inventor)

    1990-01-01

    A horn is described for transmitting sound from a transducer to a heated chamber containing an object which is levitated by acoustic energy while it is heated to a molten state, which minimizes heat transfer to thereby minimize heating of the transducer, minimize temperature variation in the chamber, and minimize loss of heat from the chamber. The forward portion of the horn, which is the portion closest to the chamber, has holes that reduce its cross-sectional area to minimize the conduction of heat along the length of the horn, with the entire front portion of the horn being rigid and having an even front face to efficiently transfer high frequency acoustic energy to fluid in the chamber. In one arrangement, the horn has numerous rows of holes extending perpendicular to the length of horn, with alternate rows extending perpendicular to one another to form a sinuous path for the conduction of heat along the length of the horn.

  17. Acoustic cloaking and transformation acoustics

    In this review, we give a brief introduction to the application of the new technique of transformation acoustics, which draws on a correspondence between coordinate transformation and material properties. The technique is formulated for both acoustic waves and linear liquid surface waves. Some interesting conceptual devices can be designed for manipulating acoustic waves. For example, we can design acoustic cloaks that make an object invisible to acoustic waves, and the cloak can either encompass or lie outside the object to be concealed. Transformation acoustics, as an analog of transformation optics, can go beyond invisibility cloaking. As an illustration for manipulating linear liquid surface waves, we show that a liquid wave rotator can be designed and fabricated to rotate the wave front. The acoustic transformation media require acoustic materials which are anisotropic and inhomogeneous. Such materials are difficult to find in nature. However, composite materials with embedded sub-wavelength resonators can in principle be made and such 'acoustic metamaterials' can exhibit nearly arbitrary values of effective density and modulus tensors to satisfy the demanding material requirements in transformation acoustics. We introduce resonant sonic materials and Helmholtz resonators as examples of acoustic metamaterials that exhibit resonant behaviour in effective density and effective modulus. (topical review)

  18. Acoustic cloaking and transformation acoustics

    Chen Huanyang [School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu 215006 (China); Chan, C T, E-mail: kenyon@ust.h, E-mail: phchan@ust.h [Department of Physics and the William Mong Institute of NanoScience and Technology, The Hong Kong University of Science and Technology, Clear Water Bay (Hong Kong)

    2010-03-24

    In this review, we give a brief introduction to the application of the new technique of transformation acoustics, which draws on a correspondence between coordinate transformation and material properties. The technique is formulated for both acoustic waves and linear liquid surface waves. Some interesting conceptual devices can be designed for manipulating acoustic waves. For example, we can design acoustic cloaks that make an object invisible to acoustic waves, and the cloak can either encompass or lie outside the object to be concealed. Transformation acoustics, as an analog of transformation optics, can go beyond invisibility cloaking. As an illustration for manipulating linear liquid surface waves, we show that a liquid wave rotator can be designed and fabricated to rotate the wave front. The acoustic transformation media require acoustic materials which are anisotropic and inhomogeneous. Such materials are difficult to find in nature. However, composite materials with embedded sub-wavelength resonators can in principle be made and such 'acoustic metamaterials' can exhibit nearly arbitrary values of effective density and modulus tensors to satisfy the demanding material requirements in transformation acoustics. We introduce resonant sonic materials and Helmholtz resonators as examples of acoustic metamaterials that exhibit resonant behaviour in effective density and effective modulus. (topical review)

  19. Use of tungsten anodes in microgap gas chambers

    In a continuation of the authors' earlier tests, tungsten has been used for anode strips in the fabrication of microgap gas chambers (MGCs) in an attempt to find a metallization suitable for gas avalanche microdetectors (MSGCs or MGCs) that will be both highly robust against sparking and yet have sufficiently low resistivity to permit use of detectors of relatively larger sizes. MGCs having about 5,500 and 7,500 angstrom thick tungsten anodes were fabricated using a sputtering technique, and the sheet resistances for these layers were measured as 0.42 and 0.27 Ω/□, respectively. The detectors were subjected to sparks having a range of energies, and the damage to the anode strips was assessed using optical and scanning electron microscope (SEM) photographs, and by measuring leakage current before and after sparking. In this paper, the spark damage test results of tungsten anodes in MGCs are reported, and an interpretation is made regarding the viability of use of this metal for larger sizes of detectors

  20. Spark gap switch with spiral gas flow

    Brucker, John P.

    1989-01-01

    A spark gap switch having a contaminate removal system using an injected gas. An annular plate concentric with an electrode of the switch defines flow paths for the injected gas which form a strong spiral flow of the gas in the housing which is effective to remove contaminates from the switch surfaces. The gas along with the contaminates is exhausted from the housing through one of the ends of the switch.

  1. SPARK Version 1.1 user manual

    This manual describes the input required to use Version 1.1 of the SPARK computer code. SPARK 1.1 is a library of FORTRAN main programs and subprograms designed to calculate eddy currents on conducting surfaces where current flow is assumed zero in the direction normal to the surface. Surfaces are modeled with triangular and/or quadrilateral elements. Lorentz forces produced by the interaction of eddy currents with background magnetic fields can be output at element nodes in a form compatible with most structural analysis codes. In addition, magnetic fields due to eddy currents can be determined at points off the surface. Version 1.1 features eddy current streamline plotting with optional hidden-surface-removal graphics and topological enhancements that allow essentially any orientable surface to be modeled. SPARK also has extensive symmetry specification options. In order to make the manual as self-contained as possible, six appendices are included that present summaries of the symmetry options, topological options, coil options and code algorithms, with input and output examples. An edition of SPARK 1.1 is available on the Cray computers at the National Magnetic Fusion Energy Computer Center at Livermore, California. Another more generic edition is operational on the VAX computers at the Princeton Plasma Physics Laboratory and is available on magnetic tape by request. The generic edition requires either the GKS or PLOT10 graphics package and the IMSL or NAG mathematical package. Requests from outside the United States will be subject to applicable federal regulations regarding dissemination of computer programs. 22 refs

  2. SPARK Version 1. 1 user manual

    Weissenburger, D.W.

    1988-01-01

    This manual describes the input required to use Version 1.1 of the SPARK computer code. SPARK 1.1 is a library of FORTRAN main programs and subprograms designed to calculate eddy currents on conducting surfaces where current flow is assumed zero in the direction normal to the surface. Surfaces are modeled with triangular and/or quadrilateral elements. Lorentz forces produced by the interaction of eddy currents with background magnetic fields can be output at element nodes in a form compatible with most structural analysis codes. In addition, magnetic fields due to eddy currents can be determined at points off the surface. Version 1.1 features eddy current streamline plotting with optional hidden-surface-removal graphics and topological enhancements that allow essentially any orientable surface to be modeled. SPARK also has extensive symmetry specification options. In order to make the manual as self-contained as possible, six appendices are included that present summaries of the symmetry options, topological options, coil options and code algorithms, with input and output examples. An edition of SPARK 1.1 is available on the Cray computers at the National Magnetic Fusion Energy Computer Center at Livermore, California. Another more generic edition is operational on the VAX computers at the Princeton Plasma Physics Laboratory and is available on magnetic tape by request. The generic edition requires either the GKS or PLOT10 graphics package and the IMSL or NAG mathematical package. Requests from outside the United States will be subject to applicable federal regulations regarding dissemination of computer programs. 22 refs.

  3. Suprathermal electrons in a vacuum spark discharge

    Bashutin, O. A.; Savjolov, A. S.

    2016-04-01

    Results of experiments on the detection of suprathermal electron beams in the plasma of a highcurrent low-inductance vacuum spark by means of space-resolved spectral X-ray polarimetry are presented. It is shown that the observed polarization of bremsstrahlung may be caused by an ~100-keV electron beam propagating along the discharge axis from the pinching region toward the anode. The influence of the discharge initiation conditions on the parameters of the generated electron beams is analyzed.

  4. Dynamics of a spark produced blast wave

    The expansion of a spark produced plasma was studied with a simple model and compared to experiments. The model and experiments were performed using a 11.2 nF capacitor bank charged up to 10kV corresponding to a total energy of 0.6 J. The nanosecond shadow pictures revealed detail structure of the shock waves, giving trajectory, speed and blast wave pressure ratios. Conversions of energy into motion and light wave were estimated

  5. The analysis of track chamber photographs using flying spot digitizers

    Powell, Brian W

    1966-01-01

    A vast quantity of data pours from the experiments on particle accelerators throughout the world. For example, over 300 000 photographs per week came from the three bubble chambers operating on the CERN PS at the end of 1965. The conventional method of processing these bubble chamber photographs is for each one of them to be examined ('scanned') to see whether it records an interesting particle interaction. The interesting photographs are then passed to hand operated measuring machines to obtain precise measurements of the particle trajectories recorded on the film. Similar measurements are carried out on photographs taken in film spark chamber experiments. This article on the Flying Spot Digitizers at CERN describes one of the most fruitful attempts to speed and make more accurate the process of analysis of bubble and spark chamber photographs. There are two types of Flying Spot Digitizer at CERN — the HPD or Hough Powell Device (named after Professor Hough and the author who, together, initiated the devel...

  6. Acoustical Imaging

    Litniewski, Jerzy; Kujawska, Tamara; 31st International Symposium on Acoustical Imaging

    2012-01-01

    The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place continuously since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2011 the 31st International Symposium on Acoustical Imaging was held in Warsaw, Poland, April 10-13. Offering both a broad perspective on the state-of-the-art as well as  in-depth research contributions by the specialists in the field, this Volume 31 in the Series contains an excellent collection of papers in six major categories: Biological and Medical Imaging Physics and Mathematics of Acoustical Imaging Acoustic Microscopy Transducers and Arrays Nondestructive Evaluation and Industrial Applications Underwater Imaging

  7. Acoustic Monitoring of the Arctic Ice Cap

    Porter, D. L.; Goemmer, S. A.; Chayes, D. N.

    2012-12-01

    Introduction The monitoring of the Arctic Ice Cap is important economically, tactically, and strategically. In the scenario of ice cap retreat, new paths of commerce open, e.g. waterways from Northern Europe to the Far East. Where ship-going commerce is conducted, the U.S. Navy and U.S. Coast Guard have always stood guard and been prepared to assist from acts of nature and of man. It is imperative that in addition to measuring the ice from satellites, e.g. Icesat, that we have an ability to measure the ice extent, its thickness, and roughness. These parameters play an important part in the modeling of the ice and the processes that control its growth or shrinking and its thickness. The proposed system consists of three subsystems. The first subsystem is an acoustic source, the second is an array of geophones and the third is a system to supply energy and transmit the results back to the analysis laboratory. The subsystems are described below. We conclude with a plan on how to tackle this project and the payoff to the ice cap modeler and hence the users, i.e. commerce and defense. System Two historically tested methods to generate a large amplitude multi-frequency sound source include explosives and air guns. A new method developed and tested by the University of Texas, ARL is a combustive Sound Source [Wilson, et al., 1995]. The combustive sound source is a submerged combustion chamber that is filled with the byproducts of the electrolysis of sea water, i.e. Hydrogen and Oxygen, an explosive mixture which is ignited via a spark. Thus, no additional compressors, gases, or explosives need to be transported to the Arctic to generate an acoustic pulse capable of the sediment and the ice. The second subsystem would be geophones capable of listening in the O(10 Hz) range and transmitting that data back to the laboratory. Thus two single arrays of geophones arranged orthogonal to each other with a range of 1000's of kilometers and a combustive sound source where the two

  8. Influence of various parameters on the formation of nitric oxide (NO) in spark ignition engines

    Ouksel, T.; Chelghoum, A. [Centre Univesitaire d' Oum El Bouaghi (Algeria). Inst. de Mecanique; Kadja, M. [Constantine Univ., Constantine (Algeria). Laboratoire d' Energetique Appliquee et de Pollution

    2006-07-01

    An ideal model was used to determine factors contributing to the formation of nitrogen monoxide (NO) in a spark ignition engine. The model divided the combustion chamber into 10 zones, each of which contained the same quantity of fuel. The combustion process was described as a front of flame successively crossing each of the zones. The model was used to assess the time-dependent thermodynamic quantities in each zone, as well as to evaluate the performance of the engine. Results of the simulation were compared with results obtained for an experiment conducted to measure 4 loading modes of an engine at a laboratory in France. Results of the study suggested that in order to reduce NO concentrations in exhaust gases, the advance-to-ignition angle must be reduced in addition to reducing the temperatures of the combustion zones by using a pre-chamber torch ignition. 11 refs., 10 figs.

  9. Component Testing of the J-2X Augmented Spark Igniter (ASI)

    Osborne, Robin J.; Peters, Warren T.; Gaspar, Kenny C.; Hauger, Katherine; Kwapisz, Mike J.

    2013-01-01

    In support of the development of the J-2X engine, 201 low pressure, liquid oxygen / liquid hydrogen (LOX/LH2) J-2X Augmented Spark Igniter (ASI) subsystem ignition tests were conducted at Marshall Space Flight Center (MSFC). The main objective of these tests was to start the ASI within the anticipated J-2X engine start box, as well as outside of it, to check for ignition margin. The setup for the J-2X ASI component testing simulated, as much as possible, the tank-head start-up configuration of the ASI within the J-2X Engine. The ignition tests were divided into 124 vacuum start tests to simulate altitude start on a flight engine, and 77 sea-level start tests to simulate the first set of ground tests for the J-2X Engine at Stennis Space Center (SSC). Other ignition parameters that were varied included propellant tank pressures, oxidizer temperature entering the ASI oxidizer feedline, oxidizer valve timing, spark igniter condition (new versus damaged), and oxidizer and fuel feedline orifice sizes. Propellant blowdowns using venturis sized to simulate the ASI resistance allowed calculation of transient propellant mass flow rates as well as global mixture ratio for all ignition tests. Global mixture ratio within the ASI at the time of ignition varied from 0.2 to 1.2. Detailed electronics data obtained from an instrumented ignition lead allowed characterization of the breakdown voltage, sustaining voltage and energy contained in each spark as the ASI propellants ignited. Results indicated that ignition always occurred within the first five sparks when both propellants were present in the ASI chamber.

  10. Development of a Micro Pixel Chamber for the ATLAS Upgrade

    Ochi, Atsuhiko; Komai, Hidetoshi; Edo, Yuki; Yamaguchi, Takahiro

    2012-01-01

    The Micro Pixel Chamber (μ-PIC) is being developed a sacandidate for the muon system of the ATLAS detector for upgrading in LHC experiments. The μ-PIC is a micro-pattern gaseous detector that doesn’t have floating structure such as wires, mesh, or foil. This detector can be made by printed-circuit-board (PCB) technology, which is commercially available and suited for mass production. Operation tests have been performed under high flux neutrons under similar conditions to the ATLAS cavern. Spark rates are measured using several gas mixtures under 7 MeV neutron irradiation, and good properties were observed using neon, ethane, and CF4 mixture of gases.Using resistive materials as electrodes, we are also developing a new μ-PIC, which is not expected to damage the electrodes in the case of discharge sparks.

  11. Modeling of Transient Heat Flux in Spark Ignition Engine During Combustion and Comparisons with Experiment

    T. F. Yusaf

    2005-01-01

    Full Text Available A quasi-one dimensional engine cycle simulation program was developed to predict the transient heat flux during combustion in a spark ignition engine. A two-zone heat release model was utilized to model the combustion process inside the combustion chamber. The fuel, air and burned gas properties throughout the engine cycle were calculated using variable specific heats. The transient heat flux inside the combustion chamber due to the change in the in-cylinder gas temperature and pressure during combustion was determined using the Woschni heat transfer model. The program was written in MATLAB together with the Graphical User Interface (GUI. Numerical results were compared with the experimental measurements and good agreement was obtained. Four thermocouples were used and positioned equi-spaced at 5mm intervals along a ray from the spark plug location on the engine head. These thermocouples were able to capture the heat flux release by the burned gas to the wall during the combustion process including the cycle-to-cycle variations. Pressure sensor was installed at the engine head to capture the pressure change throughout the cycle.

  12. Reliable Field Distortion Spark Gap for Plasma Focus

    S.HUSSAIN; M.ZAKAULLAH

    2007-01-01

    A simple,low cost,easily maintained,and reliable field distortion spark gap has been developed to operate at a voltage up to 30 kV.The header construction necessary to attach the spark gap switch to a single 12.5μF,40 kV(10 kJ)capacitor is described.The main features of the spark gap are its wide range of voltage operation,high current capacity,low inductance and long lifetime.The performance of spark gap has been tested in a plasma focus and results are presented in this report.

  13. Dual channel formation in a laser-triggered spark gap

    Kushner, M. J.; Kimura, W. D.; Ford, D. H.; Byron, S. R.

    1985-12-01

    During self-break in spark-gap switches, multiple streamers can form in close proximity to one another. The rate of expansion of these streamers is sufficiently fast that they can interact during the current pulse. To help understand how these closely spaced, expanding spark columns interact, a laser-triggered spark gap has been studied in which two parallel columns (separation 1.3 mm) are simultaneously preionized, resulting in a pair of nearly identical, axisymmetric spark columns. The spark gap (electrode separation 1.2 cm) switches a 100 ns, 40-60 kV, 12-20 kA, 1.5 Ω waterline. Interferograms of the expanding arc channels are obtained with a laser interferometer having a time and spatial resolution of 5 ns and 10 μm, respectively. Voltage and current were measured with an internal capacitive-voltage divider and a current viewing resistor. The interferograms show that for initially identical axisymmetric columns, the individual channels do not merge into a single larger axisymmetric spark column. Instead, regions of high gas density remain inside the combined column long into the recovery period. The columns also do not remain axisymmetric as they grow, indicating a long-range interaction between the channels. The voltage drop and resistance of the dual channel spark gaps changes by less than 15% from that of a single spark channel. A scaling model is presented to explain the resistance measurements and to predict the change in resistance for multichannel spark gaps.

  14. Radiation acoustics

    Lyamshev, Leonid M

    2004-01-01

    Radiation acoustics is a developing field lying at the intersection of acoustics, high-energy physics, nuclear physics, and condensed matter physics. Radiation Acoustics is among the first books to address this promising field of study, and the first to collect all of the most significant results achieved since research in this area began in earnest in the 1970s.The book begins by reviewing the data on elementary particles, absorption of penetrating radiation in a substance, and the mechanisms of acoustic radiation excitation. The next seven chapters present a theoretical treatment of thermoradiation sound generation in condensed media under the action of modulated penetrating radiation and radiation pulses. The author explores particular features of the acoustic fields of moving thermoradiation sound sources, sound excitation by single high-energy particles, and the efficiency and optimal conditions of thermoradiation sound generation. Experimental results follow the theoretical discussions, and these clearl...

  15. Acoustic levitation in the presence of gravity

    Collas, P.; Barmatz, M.; Shipley, C.

    1989-01-01

    The method of Gor'kov (1961) has been applied to derive general expressions for the total potential and force on a small spherical object in a resonant chamber in the presence of both acoustic and gravitational force fields. The levitation position is also determined in rectangular resonators for the simultaneous excitation of up to three acoustic modes, and the results are applied to the triple-axis acoustic levitator. The analysis is applied to rectangular, spherical, and cylindrical single-mode levitators that are arbitrarily oriented relative to the gravitational force field. Criteria are determined for isotropic force fields in rectangular and cylindrical resonators. It is demonstrated that an object will be situated within a volume of possible levitation positions at a point determined by the relative strength of the acoustic and gravitational fields and the orientation of the chamber relative to gravity.

  16. Development of a SPARK Training Dataset

    In its first five years, the National Nuclear Security Administration's (NNSA) Next Generation Safeguards Initiative (NGSI) sponsored more than 400 undergraduate, graduate, and post-doctoral students in internships and research positions (Wyse 2012). In the past seven years, the NGSI program has, and continues to produce a large body of scientific, technical, and policy work in targeted core safeguards capabilities and human capital development activities. Not only does the NGSI program carry out activities across multiple disciplines, but also across all U.S. Department of Energy (DOE)/NNSA locations in the United States. However, products are not readily shared among disciplines and across locations, nor are they archived in a comprehensive library. Rather, knowledge of NGSI-produced literature is localized to the researchers, clients, and internal laboratory/facility publication systems such as the Electronic Records and Information Capture Architecture (ERICA) at the Pacific Northwest National Laboratory (PNNL). There is also no incorporated way of analyzing existing NGSI literature to determine whether the larger NGSI program is achieving its core safeguards capabilities and activities. A complete library of NGSI literature could prove beneficial to a cohesive, sustainable, and more economical NGSI program. The Safeguards Platform for Automated Retrieval of Knowledge (SPARK) has been developed to be a knowledge storage, retrieval, and analysis capability to capture safeguards knowledge to exist beyond the lifespan of NGSI. During the development process, it was necessary to build a SPARK training dataset (a corpus of documents) for initial entry into the system and for demonstration purposes. We manipulated these data to gain new information about the breadth of NGSI publications, and they evaluated the science-policy interface at PNNL as a practical demonstration of SPARK's intended analysis capability. The analysis demonstration sought to answer

  17. Mathematical Simulation of Eccentricity in Spark Plug and its Effects on Combustion Parameters in Spark Ignition Engine

    A.Y. Bokhary

    2012-11-01

    Full Text Available Spark plug location on cylinder head of a spark ignition engine plays an important role on combustion characteristics. In this paper an attempt has been made to simulate the effect of eccentricity of spark plug on various combustion parameters such as the maximum temperature of the burned and unburned gas, maximum cylinder pressure and normalized flame front area and normalized flame front volume for different values of clearance height, spark advance and crank angle with the help of a two zone combustion model. The simulated results have been compared for a given value of eccentricity with Blizard and Keck [3] turbulent entrainment model and it shows reasonably good agreement.

  18. An air spark glow phase model

    A )-dimensional kinetic model is developed for the glow phase of a spark gap in air. The model includes heavy-heavy collisions leading to thermal ionization, and electron collision processes. Rates for the latter are calculated by a Boltzmann analysis and from empirical measurements. These include attachment and ionization, excitation/ionization and dissociation/ionization; detachment was found to be necessary to match experimental closing times. With only those processes, the model predicts closing times well over a wide range above and below the DC breakdown voltage

  19. Spark assisted chemical engraving (SACE) in microfactory

    Wüthrich, R.; Fujisaki, K.; Couthy, Ph; Hof, L. A.; Bleuler, H.

    2005-10-01

    Spark assisted chemical engraving (SACE) is a method for 3D microstructuring of glass or other non-conductive materials with high aspect ratio and smooth surface quality. It is applicable for rapid prototyping of microfluidic devices, for MEMS interfacing and similar applications. Typical feature size is in the hundreds of micrometres, down to a few tens of micrometres. It is a table-top technology requiring no clean rooms and no masks and with very modest space usage. It is thus well suited for microfactories. This paper gives a basic introduction to SACE and some machining examples.

  20. Vibro-acoustical instabilities induced by combustion dynamics in gas turbine combustors

    Pozarlik, Artur

    2010-01-01

    The lean premixed combustion suffers from a high sensitivity to thermo-acoustic instabilities which may occur in a combustion chamber of a gas turbine. The high level of acoustic excitation is hazardous to the combustion chamber walls (liner). The situation is even worse when mutual interaction betw

  1. Prototype multiwire proportional chamber

    1975-01-01

    Chambers of this type were initially developed within the Alpha project (finally not approved). They were designed such to minimize the radiation length with a view to a mass spectrometer of high resolution meant to replace the Omega detector. The chambers were clearly forerunners for the (drift) chambers later built for R606 with the novel technique of crimping the wires. See also photo 7510039X.

  2. Electromagnetic reverberation chambers

    Besnier, Philippe

    2013-01-01

    Dedicated to a complete presentation on all aspects of reverberation chambers, this book provides the physical principles behind these test systems in a very progressive manner. The detailed panorama of parameters governing the operation of electromagnetic reverberation chambers details various applications such as radiated immunity, emissivity, and shielding efficiency experiments.In addition, the reader is provided with the elements of electromagnetic theory and statistics required to take full advantage of the basic operational rules of reverberation chambers, including calibration proc

  3. Relativistic electrons from sparks in the laboratory

    Østgaard, N; Nisi, R S; Gjesteland, T; Grøndahl, Ø; Skeltved, A; Lehtinen, N G; Mezentsev, A; Marisaldi, M; Kochkin, P

    2016-01-01

    Discharge experiments were carried out at the Eindhoven University of Technology in 2013. The experimental setup was designed to search for electrons produced in meter-scale sparks using a 1 MV Marx generator. Negative voltage was applied to the high voltage (HV) electrode. Five thin (1 mm) plastic detectors (5 $\\rm cm^2$ each) were distributed in various configurations close to the spark gap. Earlier studies have shown (for HV negative) that X-rays are produced when a cloud of streamers is developed 30-60 cm from the negative electrode. This indicates that the electrons producing the X-rays are also accelerated at this location, that could be in the strong electric field from counterstreamers of opposite polarity. Comparing our measurements with modeling results, we find that $\\sim$300 keV electrons produced about 30-60 cm from the negative electrode are the most likely source of our measurements. A statistical analysis of expected detection of photon bursts by these fiber detectors indicates that only 20%-4...

  4. Relativistic electrons from sparks in the laboratory

    Østgaard, N.; Carlson, B. E.; Nisi, R. S.; Gjesteland, T.; Grøndahl, Ø.; Skeltved, A.; Lehtinen, N. G.; Mezentsev, A.; Marisaldi, M.; Kochkin, P.

    2016-03-01

    Discharge experiments were carried out at the Eindhoven University of Technology in 2013. The experimental setup was designed to search for electrons produced in meter-scale sparks using a 1 MV Marx generator. Negative voltage was applied to the high voltage (HV) electrode. Five thin (1 mm) plastic detectors (5 cm2 each) were distributed in various configurations close to the spark gap. Earlier studies have shown (for HV negative) that X-rays are produced when a cloud of streamers is developed 30-60 cm from the negative electrode. This indicates that the electrons producing the X-rays are also accelerated at this location, that could be in the strong electric field from counterstreamers of opposite polarity. Comparing our measurements with modeling results, we find that ˜300 keV electrons produced about 30-60 cm from the negative electrode are the most likely source of our measurements. A statistical analysis of expected detection of photon bursts by these fiber detectors indicates that only 20%-45% of the detected bursts could be from soft (˜10 keV) photons, which further supports that the majority of detected bursts are produced by relativistic electrons.

  5. Efficiency measurement for solid track spark auto counters

    The theory of solid track spark auto counters was introduced. The best etch condition was explored. Efficiency for spark auto counters was measured. The ameliorating-factor for the hull's thickness and etch-thickness was measured. The measurement for ameliorating factors and efficiency makes solid track detect system, can be used for absolute fission rate measurement. (authors)

  6. Development of a SPARK Training Dataset

    Sayre, Amanda M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Olson, Jarrod R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-03-01

    In its first five years, the National Nuclear Security Administration’s (NNSA) Next Generation Safeguards Initiative (NGSI) sponsored more than 400 undergraduate, graduate, and post-doctoral students in internships and research positions (Wyse 2012). In the past seven years, the NGSI program has, and continues to produce a large body of scientific, technical, and policy work in targeted core safeguards capabilities and human capital development activities. Not only does the NGSI program carry out activities across multiple disciplines, but also across all U.S. Department of Energy (DOE)/NNSA locations in the United States. However, products are not readily shared among disciplines and across locations, nor are they archived in a comprehensive library. Rather, knowledge of NGSI-produced literature is localized to the researchers, clients, and internal laboratory/facility publication systems such as the Electronic Records and Information Capture Architecture (ERICA) at the Pacific Northwest National Laboratory (PNNL). There is also no incorporated way of analyzing existing NGSI literature to determine whether the larger NGSI program is achieving its core safeguards capabilities and activities. A complete library of NGSI literature could prove beneficial to a cohesive, sustainable, and more economical NGSI program. The Safeguards Platform for Automated Retrieval of Knowledge (SPARK) has been developed to be a knowledge storage, retrieval, and analysis capability to capture safeguards knowledge to exist beyond the lifespan of NGSI. During the development process, it was necessary to build a SPARK training dataset (a corpus of documents) for initial entry into the system and for demonstration purposes. We manipulated these data to gain new information about the breadth of NGSI publications, and they evaluated the science-policy interface at PNNL as a practical demonstration of SPARK’s intended analysis capability. The analysis demonstration sought to answer the

  7. Acoustical Imaging

    Akiyama, Iwaki

    2009-01-01

    The 29th International Symposium on Acoustical Imaging was held in Shonan Village, Kanagawa, Japan, April 15-18, 2007. This interdisciplinary Symposium has been taking place every two years since 1968 and forms a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. In the course of the years the volumes in the Acoustical Imaging Series have developed and become well-known and appreciated reference works. Offering both a broad perspective on the state-of-the-art in the field as well as an in-depth look at its leading edge research, this Volume 29 in the Series contains again an excellent collection of seventy papers presented in nine major categories: Strain Imaging Biological and Medical Applications Acoustic Microscopy Non-Destructive Evaluation and Industrial Applications Components and Systems Geophysics and Underwater Imaging Physics and Mathematics Medical Image Analysis FDTD method and Other Numerical Simulations Audience Researcher...

  8. Acoustic telemetry

    National Oceanic and Atmospheric Administration, Department of Commerce — To determine movements of green turtles in the nearshore foraging areas, we deployed acoustic tags and determined their movements through active and passive...

  9. Acoustics Research

    National Oceanic and Atmospheric Administration, Department of Commerce — Fisheries acoustics data are collected from more than 200 sea-days each year aboard the FRV DELAWARE II and FRV ALBATROSS IV (decommissioned) and the FSV Henry B....

  10. Battlefield acoustics

    Damarla, Thyagaraju

    2015-01-01

    This book presents all aspects of situational awareness in a battlefield using acoustic signals. It starts by presenting the science behind understanding and interpretation of sound signals. The book then goes on to provide various signal processing techniques used in acoustics to find the direction of sound source, localize gunfire, track vehicles, and detect people. The necessary mathematical background and various classification and fusion techniques are presented. The book contains majority of the things one would need to process acoustic signals for all aspects of situational awareness in one location. The book also presents array theory, which is pivotal in finding the direction of arrival of acoustic signals. In addition, the book presents techniques to fuse the information from multiple homogeneous/heterogeneous sensors for better detection. MATLAB code is provided for majority of the real application, which is a valuable resource in not only understanding the theory but readers, can also use the code...

  11. High resolution drift chambers

    High precision drift chambers capable of achieving less than or equal to 50 μm resolutions are discussed. In particular, we compare so called cool and hot gases, various charge collection geometries, several timing techniques and we also discuss some systematic problems. We also present what we would consider an ''ultimate'' design of the vertex chamber. 50 refs., 36 figs., 6 tabs

  12. BEBC bubble chamber

    1972-01-01

    Looking up into the interior of BEBC bubble chamber from the expansion cylinder. At the top of the chamber two fish-eye lenses are installed and three other fish-eye ports are blanked off. In the centre is a heat exchanger.

  13. A spectroscopy study of gasoline partially premixed compression ignition spark assisted combustion

    Highlights: ► PPC combustion combined with spark assistance and gasoline fuel on a CI engine. ► Chemiluminescence of different chemical species describes the progress of combustion reaction. ► Spectra of a novel combustion mode under SACI conditions is described. ► UV–Visible spectrometry, high speed imaging and pressure diagnostic were employed for analysis. - Abstract: Nowadays many research efforts are focused on the study and development of new combustion modes, mainly based on the use of locally lean air–fuel mixtures. This characteristic, combined with exhaust gas recirculation, provides low combustion temperatures that reduces pollutant formation and increases efficiency. However these combustion concepts have some drawbacks, related to combustion phasing control, which must be overcome. In this way, the use of a spark plug has shown to be a good solution to improve phasing control in combination with lean low temperature combustion. Its performance is well reported on bibliography, however phenomena involving the combustion process are not completely described. The aim of the present work is to develop a detailed description of the spark assisted compression ignition mode by means of application of UV–Visible spectrometry, in order to improve insight on the combustion process. Tests have been performed in an optical engine by means of broadband radiation imaging and emission spectrometry. The engine hardware is typical of a compression ignition passenger car application. Gasoline was used as the fuel due to its low reactivity. Combining broadband luminosity images with pressure-derived heat-release rate and UV–Visible spectra, it was possible to identify different stages of the combustion reaction. After the spark discharge, a first flame kernel appears and starts growing as a premixed flame front, characterized by a low and constant heat-release rate in combination with the presence of remarkable OH radical radiation. Heat release increases

  14. Electroacoustical simulation of listening room acoustics for project ARCHIMEDES

    Bech, Søren

    1989-01-01

    ARCHIMEDES is a psychoacoustics research project, funded under the European EUREKA scheme. Three partners share the work involved: The Acoustics Laboratory of The Technical University of Denmark; Bang and Olufsen of Denmark; and KEF Electronics of England. Its primary object is to quantify the influence of listening room acoustics on the timbre of reproduced sound. For simulation of the acoustics of a standard listening room, an electroacoustic setup has been built in an anechoic chamber. The...

  15. Nonlinear control of a spark ignition engine

    Bidan, P. [Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France); Boverie, S.; Chaumerliac, V. [Siemens AutomotiveSA, MIRGAS Laboratory, 31 - Toulouse (France)

    1994-12-31

    This paper describes the improvements which can be made to spark ignition engine by extensive use of automatic control. Particular emphasis is placed on fast transient phases produced by simultaneous action on the throttle and the electronic fuel injection device. The aim is to achieve better performance for the fuel/air ratio regulation system, thereby improving engine efficiency and exhaust emission during these transient phases. The authors begin by presenting an average dynamic model of the intake manifold validated on an engine test bench and goes on to develop a closed-loop system controlling average pressure in the intake manifold using the reference tracking model method. The air supply control system is combined with a predictor to compensate for delays in the injection procedure. The paper concludes with a comparison between the results obtained using simulation and those obtained experimentally from the engine. (author) 10 refs.

  16. OPAL Jet Chamber Prototype

    OPAL was one of the four experiments installed at the LEP particle accelerator from 1989 - 2000. OPAL's central tracking system consists of (in order of increasing radius) a silicon microvertex detector, a vertex detector, a jet chamber, and z-chambers. All the tracking detectors work by observing the ionization of atoms by charged particles passing by: when the atoms are ionized, electrons are knocked out of their atomic orbitals, and are then able to move freely in the detector. These ionization electrons are detected in the dirfferent parts of the tracking system. This piece is a prototype of the jet chambers

  17. Comparative Studies on Performance Parameters and Exhaust Emissions from Two Stroke Copper Coated Spark Ignition Engine with Alcohol Blended Gasoline with Catalytic Converter

    S. Narasimha Kumar*1; M.V.S. Murali Krishna; P.V.K.Murthy

    2014-01-01

    Experiments were conducted to evaluate the performance and control the exhaust emissions from two-stroke, single cylinder, spark ignition (SI) engine, with alcohol blended gasoline (80% gasoline, 10% methanol, 10% ethanol by volume) having copper coated combustion chamber [CCCC, copper-(thickness, 300 µ) coated on piston crown, inner side of cylinder head] provided with catalytic converter with sponge iron as catalyst and compared with conventional SI engine (CE) with pure gas...

  18. My 65 years in acoustics

    Beranek, Leo L.

    2001-05-01

    My entry into acoustics began as research assistant to Professor F. V. Hunt at Harvard University. I received my doctorate in 1940 and directed the Electro-Acoustic Laboratory at Harvard from October 1940 until September 1945. In 1947, I became a tenured associate professor at MIT, and, with Richard H. Bolt, formed the consulting firm Bolt and Beranek, that later included Robert B. Newman, becoming BBN. My most significant contributions before 1970 were design of wedge-lined anechoic chambers, systemization of noise reduction in ventilation systems, design of the world's largest muffler for the testing of supersonic jet engines at NASA's Lewis Laboratory in Cleveland, speech interference level, NC noise criterion curves, heading New York Port Authority's noise study that resulted in mufflers on jet aircraft, and steep aircraft climb procedures, and publishing books titled, Acoustical Measurements, Acoustics, Noise Reduction, Noise and Vibration Control, and Music, Acoustics and Architecture. As President of BBN, I supervised the formation of the group that built and operated the ARPANET (1969), which, when split in two (using TCP/IP protocol) became the INTERNET (1984). Since then, I have written two books on Concert Halls and Opera Houses and have consulted on four concert halls and an opera house.

  19. Bluetooth Communication Interface for EEG Signal Recording in Hyperbaric Chambers.

    Pastena, Lucio; Formaggio, Emanuela; Faralli, Fabio; Melucci, Massimo; Rossi, Marco; Gagliardi, Riccardo; Ricciardi, Lucio; Storti, Silvia F

    2015-07-01

    Recording biological signals inside a hyperbaric chamber poses technical challenges (the steel walls enclosing it greatly attenuate or completely block the signals as in a Faraday cage), practical (lengthy cables creating eddy currents), and safety (sparks hazard from power supply to the electronic apparatus inside the chamber) which can be overcome with new wireless technologies. In this technical report we present the design and implementation of a Bluetooth system for electroencephalographic (EEG) recording inside a hyperbaric chamber and describe the feasibility of EEG signal transmission outside the chamber. Differently from older systems, this technology allows the online recording of amplified signals, without interference from eddy currents. In an application of this technology, we measured EEG activity in professional divers under three experimental conditions in a hyperbaric chamber to determine how oxygen, assumed at a constant hyperbaric pressure of 2.8 ATA , affects the bioelectrical activity. The EEG spectral power estimated by fast Fourier transform and the cortical sources of the EEG rhythms estimated by low-resolution brain electromagnetic analysis were analyzed in three different EEG acquisitions: breathing air at sea level; breathing oxygen at a simulated depth of 18 msw, and breathing air at sea level after decompression. PMID:25608308

  20. Gridded ionization chamber

    An improved ionization chamber type x-ray detector comprises a heavy gas at high pressure disposed between an anode and a cathode. An open grid structure is disposed adjacent the anode and is maintained at a voltsge intermediate between the cathode and anode potentials. The electric field which is produced by positive ions drifting toward the cathode is thus shielded from the anode. Current measuring circuits connected to the anode are, therefore, responsive only to electron current flow within the chamber and the recovery time of the chamber is shortened. The grid structure also serves to shield the anode from electrical currents which might otherwise be induced by mechanical vibrations in the ionization chamber structure

  1. ALICE Time Projection Chamber

    Lippmann, C

    2013-01-01

    The Time Projection Chamber (TPC) is the main device in the ALICE 'central barrel' for the tracking and identification (PID) of charged particles. It has to cope with unprecedented densities of charges particles.

  2. Toxic Test Chambers

    Federal Laboratory Consortium — Description/History: Hazardous material test facility Both facilities have 16,000 cubic foot chambers, equipped with 5000 CFM CBR filter systems with an air change...

  3. Calorimetry with flash chambers

    The flash chambers used in the Fermilab E594 neutrino experiment are described, and their use in a calorimeter discussed. Resolutions obtained with a calibration beam are presented, and comments made about the pattern recognition capabilities of the calorimeter

  4. Detecting dark matter with scintillating bubble chambers

    Zhang, Jianjie; Dahl, C. Eric; Jin, Miaotianzi; Baxter, Daniel

    2016-03-01

    Threshold based direct WIMP dark matter detectors such as the superheated bubble chambers developed by the PICO experiment have demonstrated excellent electron-recoil and alpha discrimination, excellent scalability, ease of change of target fluid, and low cost. However, the nuclear-recoil like backgrounds have been a limiting factor in their dark matter sensitivity. We present a new type of detector, the scintillating bubble chamber, which reads out the scintillation pulse of the scattering events as well as the pressure, temperature, acoustic traces, and bubble images as a conventional bubble chamber does. The event energy provides additional handle to discriminate against the nuclear-recoil like backgrounds. Liquid xenon is chosen as the target fluid in our prototyping detector for its high scintillation yield and suitable vapor pressure which simplifies detector complexity. The detector can be used as an R&D tool to study the backgrounds present in the current PICO bubble chambers or as a prototype for standalone dark matter detectors in the future. Supported by DOE Grant DE-SC0012161.

  5. Spark and Deligne-Beilinson cohomology on orbifolds

    Du, Cheng-Yong; Zhao, Xiaojuan

    2016-06-01

    A homological spark complex (FU∗, EU∗, IU∗) is constructed for any good atlas U of an effective orbifold X =(X , [ U ]) . It is proved that all these homological spark complexes are quasi-isomorphic for X. Furthermore, smooth Deligne-Beilinson cohomology HDp (X , Z(q)) of X is investigated and it is shown that the ring Hˆ∗(X) of spark classes of X is isomorphic to the subring HD∗ (X , Z(∗)) of the orbifold Deligne-Beilinson cohomology ring of X.

  6. Bubble chamber: antiproton annihilation

    1971-01-01

    These images show real particle tracks from the annihilation of an antiproton in the 80 cm Saclay liquid hydrogen bubble chamber. A negative kaon and a neutral kaon are produced in this process, as well as a positive pion. The invention of bubble chambers in 1952 revolutionized the field of particle physics, allowing real tracks left by particles to be seen and photographed by expanding liquid that had been heated to boiling point.

  7. Gridded Ionization Chamber

    In the present paper the working principles of a gridded ionization chamber are given, and all the different factors that determine its resolution power are analyzed in detail. One of these devices, built in the Physics Division of the JEN and designed specially for use in measurements of alpha spectroscopy, is described. finally the main applications, in which the chamber can be used, are shown. (Author) 17 refs

  8. Acoustic emission

    This paper is related to our activities on acoustic emission (A.E.). The work is made with different materials: metals and fibre reinforced plastics. At present, acoustic emission transducers are being developed for low and high temperature. A test to detect electrical discharges in electrical transformers was performed. Our experience in industrial tests to detect cracks or failures in tanks or tubes is also described. The use of A.E. for leak detection is considered. Works on pattern recognition of A.E. signals are also being performed. (Author)

  9. 46 CFR 30.10-63 - Spark arrester-TB/ALL.

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Spark arrester-TB/ALL. 30.10-63 Section 30.10-63...-63 Spark arrester—TB/ALL. The term spark arrester means any device, assembly, or method of a... sparks in exhaust pipes from internal combustion engines....

  10. Acoustic field effects on a negative corona discharge

    For a negative corona discharge under atmospheric pressure in different regimes, we investigated the effects of an acoustic field both on its electrical parameters and on the change in its visual appearance. We found that the application of an acoustic field on the true corona discharge, for particular currents, decreases the discharge voltage. The application of an acoustic field on the discharge in the filamentary streamer regime substantially extends the range of currents for which the discharge voltage remains more or less constant, i.e. it allows a substantial increase in the power delivered to the discharge. The application of an acoustic field on the discharge causes the discharge to spread within the discharge chamber and consequently, a highly reactive non-equilibrium plasma is created throughout the inter-electrode space. Finally, our experimental apparatus radiates almost no acoustic energy from the discharge chamber. (paper)

  11. Acoustic field effects on a negative corona discharge

    Bálek, R.; Červenka, M.; Pekárek, S.

    2014-06-01

    For a negative corona discharge under atmospheric pressure in different regimes, we investigated the effects of an acoustic field both on its electrical parameters and on the change in its visual appearance. We found that the application of an acoustic field on the true corona discharge, for particular currents, decreases the discharge voltage. The application of an acoustic field on the discharge in the filamentary streamer regime substantially extends the range of currents for which the discharge voltage remains more or less constant, i.e. it allows a substantial increase in the power delivered to the discharge. The application of an acoustic field on the discharge causes the discharge to spread within the discharge chamber and consequently, a highly reactive non-equilibrium plasma is created throughout the inter-electrode space. Finally, our experimental apparatus radiates almost no acoustic energy from the discharge chamber.

  12. Exploring the Performance of Spark for a Scientific Use Case

    Sehrish, Saba [Fermilab; Kowalkowski, Jim [Fermilab; Paterno, Marc [Fermilab

    2016-01-01

    We present an evaluation of the performance of a Spark implementation of a classification algorithm in the domain of High Energy Physics (HEP). Spark is a general engine for in-memory, large-scale data processing, and is designed for applications where similar repeated analysis is performed on the same large data sets. Classification problems are one of the most common and critical data processing tasks across many domains. Many of these data processing tasks are both computation- and data-intensive, involving complex numerical computations employing extremely large data sets. We evaluated the performance of the Spark implementation on Cori, a NERSC resource, and compared the results to an untuned MPI implementation of the same algorithm. While the Spark implementation scaled well, it is not competitive in speed to our MPI implementation, even when using significantly greater computational resources.

  13. Sintering of zirconia ceramics using microwave and spark heating techniques

    Ivashutenko, A. S.; Frangulyan, T. S.; Ghyngazov, S. A.; Petrova, A. B.

    2016-02-01

    The paper presents the results of an complex study of structural and mechanical properties of zirconia ceramics sintered using different techniques. The samples were sintered via the conventional method of heating, in the field of microwave radiation and spark plasma. The experimental data indicates that a microwave field and spark plasma have a stimulating effect on zirconia ceramics sintering. In contrast to the microwave sintering, spark plasma sintering provides ceramics with improved properties at similar time-temperature annealing modes. Moreover, the properties of the ceramics under spark plasma sintering at T=1300 °C are similar to the properties of the ceramics sintered in a microwave field at T=1400 °C.

  14. A multi-channel, optically coupled spark gap monitor system

    The authors describe a spark gap monitor system installed on FRX-C Large Source Modification (LSM), a theta pinch experiment which forms field-reversed configuration (FRC) compact toroids. The field reversing theta pinch produces a vacuum magnetic field of 10kG inside the single turn, 2-m-long straight 0.7-m-id coil by discharging in series 2,50kV, 200 μF capacitor banks with a total of 140 2.81 μF capacitors, each with a start spark-gap switch and a piggy-back crowbar spark-gap switch. Efficient operation of the bank requires information on the timing and function of each capacitor-spark gap unit

  15. Research of EDM Spark Locations in Die-sinking

    韩强; 何勇; 杨向萍

    2004-01-01

    Detection of 2-dimention spark locations by electromagnetic detection method in electrical discharge machining (EDM) is studied. The method, which is applied and investigated, is based on the fact that the release of energy from a spark is transformed into electromagnetic wave around the workpiece. A new sensor system composed of high precision linear Hall components and cubic ferrite is used to detect the intensity of magnetic field. Relation equation between the output of the sensor system and 2-dimention spark locations experiment under a spiculate electrode is introduced, and its diagram of curve is drawn. As a result, the information that can be achieved by detecting spark's location gives new possibilities for an extended analysis of the EDM-process.

  16. High pressure gas-filled cermet spark gaps

    The results of modernization of the R-48 and R-49 spark gaps making it possible to improve their electrical characteristics are presented. The design is described and characteristics of gas-filled cermet spark gaps are presented. By the voltage rise time of 5-6 μs in the Marx generator scheme they provide for the pulse break-through voltage of 120 and 150 kV. By the voltage rise time of 0.5-1 μs the break-through voltage of these spark gaps may be increased up to 130 and 220 kV. The proper commutation time is equal to ≤ 0.5 ns. Practical recommendations relative to designing cermet spark gaps are given

  17. Assessment of Calcium Sparks in Intact Skeletal Muscle Fibers

    Park, Ki Ho; Weisleder, Noah; Zhou, Jingsong; Gumpper, Kristyn; Zhou, Xinyu; Duann, Pu; Ma, Jianjie; Lin, Pei-Hui

    2014-01-01

    Maintaining homeostatic Ca2+ signaling is a fundamental physiological process in living cells. Ca2+ sparks are the elementary units of Ca2+ signaling in the striated muscle fibers that appear as highly localized Ca2+ release events mediated by ryanodine receptor (RyR) Ca2+ release channels on the sarcoplasmic reticulum (SR) membrane. Proper assessment of muscle Ca2+ sparks could provide information on the intracellular Ca2+ handling properties of healthy and diseased striated muscles. Althoug...

  18. Acoustics and Hearing

    Damaske, Peter

    2008-01-01

    When one listens to music at home, one would like to have an acoustic impression close to that of being in the concert hall. Until recently this meant elaborate multi-channelled sound systems with 5 or more speakers. But head-related stereophony achieves the surround-sound effect in living rooms with only two loudspeakers. By virtue of their slight directivity as well as an electronic filter the limitations previously common to two-speaker systems can be overcome and this holds for any arbitrary two-channel recording. The book also investigates the question of how a wide and diffuse sound image can arise in concert halls and shows that the quality of concert halls decisively depends on diffuse sound images arising in the onset of reverberation. For this purpose a strong onset of reverberation is modified in an anechoic chamber by electroacoustic means. Acoustics and Hearing proposes ideas concerning signal processing in the auditory system that explain the measured results and the resultant sound effects plea...

  19. Target Chamber Manipulator

    Tantillo, Anthony; Watson, Matthew

    2015-11-01

    A system has been developed to allow remote actuation of sensors in a high vacuum target chamber used with a particle accelerator. Typically, sensors of various types are placed into the target chamber at specific radial and angular positions relative to the beam line and target. The chamber is then evacuated and the experiments are performed for those sensor positions. Then, the chamber is opened, the sensors are repositioned to new angles or radii, and the process is repeated, with a separate pump-down cycle for each set of sensor positions. The new sensor positioning system allows scientists to pre-set the radii of up to a dozen sensors, and then remotely actuate their angular positions without breaking the vacuum of the target chamber. This reduces the time required to reposition sensors from 6 hours to 1 minute. The sensors are placed into one of two tracks that are separately actuated using vacuum-grade stepping motors. The positions of the sensors are verified using absolute optical rotary encoders, and the positions are accurate to 0.5 degrees. The positions of the sensors are electronically recorded and time-stamped after every change. User control is through a GUI using LabVIEW.

  20. Study of aerosol behaviour in an acoustic field

    The average size of an aerosol submitted to acoustic waves is increased. This results from coagulation of the finer particles on the larger ones. An experimental apparatus was developed in order to control the evolution of aerosol distribution in an acoustic field. Important deposition on the walls of the agglomeration chamber was observed as a consequence of the acoustically induced turbulent flow. Consequently, we experimentally evaluated the turbulent properties of the system. A granular bed submitted to an acoustic field and set downstream an agglomerator constitutes an almost absolute filter for an usually penetrating aerosol

  1. Spark plasma sintering of aluminum matrix composites

    Yadav, Vineet

    2011-12-01

    Aluminum matrix composites make a distinct category of advanced engineering materials having superior properties over conventional aluminum alloys. Aluminum matrix composites exhibit high hardness, yield strength, and excellent wear and corrosion resistance. Due to these attractive properties, aluminum matrix composites materials have many structural applications in the automotive and the aerospace industries. In this thesis, efforts are made to process high strength aluminum matrix composites which can be useful in the applications of light weight and strong materials. Spark Plasma Sintering (SPS) is a relatively novel process where powder mixture is consolidated under the simultaneous influence of uniaxial pressure and pulsed direct current. In this work, SPS was used to process aluminum matrix composites having three different reinforcements: multi-wall carbon nanotubes (MWCNTs), silicon carbide (SiC), and iron-based metallic glass (MG). In Al-CNT composites, significant improvement in micro-hardness, nano-hardness, and compressive yield strength was observed. The Al-CNT composites further exhibited improved wear resistance and lower friction coefficient due to strengthening and self-lubricating effects of CNTs. In Al-SiC and Al-MG composites, microstructure, densification, and tribological behaviors were also studied. Reinforcing MG and SiC also resulted in increase in micro-hardness and wear resistance.

  2. NEWS: Don't forget Sparks!

    2000-07-01

    Following our early notification of the `creating SPARKS' festival in London (see Phys. Educ. January 2000 p 7) more details of the programme have now been made available. The event takes place on 6-30 September in South Kensington and the lengthy programme of talks and sessions covers such items as: Science writing; A sustainable world - the issues; Hands-on particle physics; Powering into the new millennium - innovative transport and energy solutions; The enigma of time; Scientific futures in contemporary science fiction; The cases for and against nuclear energy; The microscopic world of superconductors; Michael Faraday; Quantum information - parallelism, secrecy and teleportation; and The origin of the solar system. Among the speakers are Sir Eric Ash, Nigel Henbest, Professors Cyril Hilsum, Peter Landsberg and Richard Palmer. The Science Museum's new Wellcome Wing devoted to contemporary science and technology will be open for viewing, children will attend science and arts hands-on workshops at the Royal Albert Hall on Friday 15 September, and leading scientists will be discussing the scientific developments of the future at Imperial College. In addition the Victoria and Albert Museum will demonstrate how science is involved in the creation, appreciation and conservation of the Musuem's collections. Full programmes for the festival will be available this month from the South Kensington institutions, the festival website (www.creatingsparks.co.uk) or by calling 0906 402 0022.

  3. The KLOE drift chamber

    Adinolfi, M.; Aloisio, A.; Ambrosino, F.; Andryakov, A.; Antonelli, A.; Antonelli, M.; Anulli, F.; Bacci, C.; Bankamp, A.; Barbiellini, G.; Bellini, F.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocci, V.; Bossi, F.; Branchini, P.; Bulychjov, S.A.; Cabibbo, G.; Calcaterra, A.; Caloi, R.; Campana, P.; Capon, G.; Carboni, G.; Cardini, A.; Casarsa, M.; Cataldi, G.; Ceradini, F.; Cervelli, F.; Cevenini, F.; Chiefari, G.; Ciambrone, P.; Conetti, S.; Conticelli, S.; Lucia, E. De; Robertis, G. De; Sangro, R. De; Simone, P. De; Zorzi, G. De; Dell' Agnello, S.; Denig, A.; Domenico, A. Di; Donato, C. Di; Falco, S. Di; Doria, A.; Drago, E.; Elia, V.; Erriquez, O.; Farilla, A.; Felici, G.; Ferrari, A.; Ferrer, M.L.; Finocchiaro, G.; Forti, C.; Franceschi, A.; Franzini, P.; Gao, M.L.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Golovatyuk, V.; Gorini, E.; Grancagnolo, F.; Grandegger, W.; Graziani, E.; Guarnaccia, P.; Hagel, U.V.; Han, H.G.; Han, S.W.; Huang, X.; Incagli, M.; Ingrosso, L.; Jang, Y.Y.; Kim, W.; Kluge, W.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee-Franzini, J.; Lomtadze, F.; Luisi, C.; Mao, C.S.; Martemianov, M.; Matsyuk, M.; Mei, W.; Merola, L.; Messi, R.; Miscetti, S.; Moalem, A.; Moccia, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nedosekin, A.; Panareo, M.; Pacciani, L.; Pages, P.; Palutan, M.; Paoluzi, L.; Pasqualucci, E.; Passalacqua, L.; Passaseo, M.; Passeri, A.; Patera, V.; Petrolo, E.; Petrucci, G.; Picca, D.; Pirozzi, G.; Pistillo, C.; Pollack, M.; Pontecorvo, L.; Primavera, M.; Ruggieri, F.; Santangelo, P.; Santovetti, E.; Saracino, G.; Schamberger, R.D.; Schwick, C.; Sciascia, B.; Sciubba, A.; Scuri, F.; Sfiligoi, I.; Shan, J.; Silano, P.; Spadaro, T.; Spagnolo, S.; Spiriti, E.; Stanescu, C.; Tong, G.L.; Tortora, L.; Valente, E.; Valente, P. E-mail: paolo.valente@lnf.infn.it; Valeriani, B.; Venanzoni, G.; Veneziano, S.; Wu, Y.; Xie, Y.G.; Zhao, P.P.; Zhou, Y

    2001-04-01

    The tracking detector of the KLOE experiment is 4 m diameter, 3.3 m length drift chamber, designed to contain a large fraction of the decays of low-energy K{sub L} produced at the Frascati DAPHINE phi-factory. The chamber is made by a thin carbon fiber structure and operated with a helium-based gas mixture in order to minimise conversion of low-energy photons and multiple scattering inside the sensitive volume. The tracking information is provided by 58 layers of stereo wires defing 12,582 cells, 2x2 cm{sup 2} in size in the 12 innermost layers and 3x3 cm{sup 2} in the outer ones. Details of the chamber design, calibration procedure and tracking performances are presented.

  4. The KLOE drift chamber

    The tracking detector of the KLOE experiment is 4 m diameter, 3.3 m length drift chamber, designed to contain a large fraction of the decays of low-energy KL produced at the Frascati DAPHINE phi-factory. The chamber is made by a thin carbon fiber structure and operated with a helium-based gas mixture in order to minimise conversion of low-energy photons and multiple scattering inside the sensitive volume. The tracking information is provided by 58 layers of stereo wires defing 12,582 cells, 2x2 cm2 in size in the 12 innermost layers and 3x3 cm2 in the outer ones. Details of the chamber design, calibration procedure and tracking performances are presented

  5. Automated Electrostatics Environmental Chamber

    Calle, Carlos; Lewis, Dean C.; Buchanan, Randy K.; Buchanan, Aubri

    2005-01-01

    The Mars Electrostatics Chamber (MEC) is an environmental chamber designed primarily to create atmospheric conditions like those at the surface of Mars to support experiments on electrostatic effects in the Martian environment. The chamber is equipped with a vacuum system, a cryogenic cooling system, an atmospheric-gas replenishing and analysis system, and a computerized control system that can be programmed by the user and that provides both automation and options for manual control. The control system can be set to maintain steady Mars-like conditions or to impose temperature and pressure variations of a Mars diurnal cycle at any given season and latitude. In addition, the MEC can be used in other areas of research because it can create steady or varying atmospheric conditions anywhere within the wide temperature, pressure, and composition ranges between the extremes of Mars-like and Earth-like conditions.

  6. Electric Spark Sensitivity of Polynitro Compounds. Part V. A Relationship between Electric Spark and Impact Sensitivities of Energetic Materials

    2001-01-01

    The spark energy, EES, required for 50 percent initiation probability of 41 polynitro compounds was determined. The relationships between the EES values and impact sensitivity, expressed as drop energies Ed of the "first reaction", were established and discussed. The conclusion is made that depending on intermolecular interaction factors in crystals of energetic materials, the mechanism of impact energy transition to the reaction centre of their molecule can be differ from that of transition of energy of electric spark.

  7. Display of a proton-proton interaction as seen in the streamer chamber of NA5

    1979-01-01

    This experiment was performed by the Bari-Cracow-Liverpool-Munich (MPI)-Nijmegen Collaboration using the unseparated H2 beam in the EHN1 hall. The setup consisted of a three-gap streamer chamber (2x1.4x0.72 m3) inside a superconducting vertex magnet, large magnetostrictive spark chambers, proportional chambers and beam defining counters. A large acceptance electron and hadron calorimeter completed the setup. Particles from beam interactions on a target, 36.5 cm long, 2 cm in diameter (for liquid hydrogen) located inside the chamber at its entrance were photographed. Multiplicities, rapidity distributions, and correlations were studied for interactions with a large value for the sum of the transverse momenta.

  8. Acoustic lenses

    Acoustic lenses focus ultrasound to produce pencil-like beams with reduced near fields. When fitted to conventional (flat-faced) transducers, such lenses greatly improve the ability to detect and size defects. This paper describes a program developed to design acoustic lenses for use in immersion or contact inspection, using normal or angle beam mode with flat or curved targets. Lens surfaces are circular in geometry to facilitate machining. For normal beam inspection of flat plate, spherical or cylindrical lenses are used. For angle beam or curved surface inspections, a compound lens is required to correct for the extra induced aberration. Such a lens is aspherical with one radius of curvature in the plane of incidence, and a different radius of curvature in the plane perpendicular to the incident plane. The resultant beam profile (i.e., location of the acoustic focus, beam diameter, 6 dB working range) depends on the degree of focusing and the transducer used. The operating frequency and bandwidth can be affected by the instrumentation used. Theoretical and measured beam profiles are in good agreement. Various applications, from zone focusing used for defect sizing in thick plate, to line focusing for pipe weld inspection, are discussed

  9. LEP Vacuum Chamber

    1983-01-01

    This is a cut-out of a LEP vacuum chamber for dipole magnets showing the beam channel and the pumping channel with the getter (NEG) strip and its insulating supports. A water pipe connected to the cooling channel can also be seen at the back.The lead radiation shield lining is also shown. See also 8305563X.

  10. Drift chamber detectors

    A review of High Energy Physics detectors based on drift chambers is presented. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysied, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author)

  11. LEP vacuum chamber, prototype

    1983-01-01

    Final prototype for the LEP vacuum chamber, see 8305170 for more details. Here we see the strips of the NEG pump, providing "distributed pumping". The strips are made from a Zr-Ti-Fe alloy. By passing an electrical current, they were heated to 700 deg C.

  12. Wire chamber conference

    This booklet contains program and the abstracts of the papers presented at the conference, most of them dealing with performance testing of various types of wire chambers. The publication of proceedings is planned as a special issue of 'Nuclear instruments and methods' later on. All abstracts are in English. An author index for the book of abstracts is given. (A.N.)

  13. Scanning bubble chamber pictures

    1974-01-01

    These were taken at the 2 m hydrogen bubble chamber. The photo shows an early Shiva system where the pre-measurements needed to qualify the event were done manually (cf photo 7408136X). The scanning tables were located in bld. 12. Gilberte Saulmier sits on foreground, Inge Arents at centre.

  14. Spark-safe low-voltage detonator

    Lieberman, M.L.

    1988-07-01

    A column of explosive in a low-voltage detonator which makes it spark-safe includes an organic secondary explosive charge of HMX in the form of a thin pad disposed in a bore of a housing of the detonator in an ignition region of the explosive column and adjacent to an electrical ignition device at one end of the bore. The pad of secondary charge has an axial thickness within the range of twenty to thirty percent of its diameter. The explosive column also includes a first explosive charge of CP disposed in the housing bore in the ignition region of the explosive column next to the secondary charge pad on a side opposite from the ignition device. The first CP charge is loaded under sufficient pressure, 25 to 40 kpsi, to provide mechanical confinement of the pad of secondary charge and physical coupling thereof with the ignition device. The explosive column further includes a second explosive charge of CP disposed in the housing bore in a transition region of the explosive column next to the first CP charge on a side opposite from the pad of secondary charge. The second CP charge is loaded under sufficient pressure, about 10 kpsi, to allow occurrence of DDT. The first explosive CP charge has an axial thickness within the range of twenty to thirty percent of its diameter, whereas the second explosive CP charge contains a series of increments (nominally 4), each of which has an axial thickness-to-diameter ratio of one to two. 2 figs.

  15. Spark counting technique with an aluminium oxide film

    Automatic spark counting of etch-pits on a polycarbonate film produced by nuclear fission fragments is now used for neutron monitoring in several countries. A method was developed using an aluminium oxide film instead of a polycarbonate as the neutron detector. Aluminium oxide films were prepared as follows: A cleaned aluminium plate as an anode and a nickel plate as a cathode were immersed in dilute sulfuric acid solution and electric current flowed between the electrodes at 12degC for 10-30 minutes. Electric current density was about 10 mA/cm2. The aluminium plate was then kept in boiling water for 10-30 minutes for sealing. The thickness of the aluminium oxide layer formed was about 1μm. The aluminium plate attached to a plate of suitable fissionable material, such as uranium or thorium, was irradiated with neutrons and set in a usual spark counter for fission track counting. One electrode was the aluminium plate and the other was an aluminized polyester sheet. Sparked pulses were counted with a usual scaler. The advantage of using spark counting with an aluminium oxide film for neutron monitoring is rapid measurement of neutron exposure, since chemical etching which is indispensable for spark counting with a polycarbonate detector film, is not needed. (H.K.)

  16. Acoustic force mapping in a hybrid acoustic-optical micromanipulation device supporting high resolution optical imaging.

    Thalhammer, Gregor; McDougall, Craig; MacDonald, Michael Peter; Ritsch-Marte, Monika

    2016-04-12

    Many applications in the life-sciences demand non-contact manipulation tools for forceful but nevertheless delicate handling of various types of sample. Moreover, the system should support high-resolution optical imaging. Here we present a hybrid acoustic/optical manipulation system which utilizes a transparent transducer, making it compatible with high-NA imaging in a microfluidic environment. The powerful acoustic trapping within a layered resonator, which is suitable for highly parallel particle handling, is complemented by the flexibility and selectivity of holographic optical tweezers, with the specimens being under high quality optical monitoring at all times. The dual acoustic/optical nature of the system lends itself to optically measure the exact acoustic force map, by means of direct force measurements on an optically trapped particle. For applications with (ultra-)high demand on the precision of the force measurements, the position of the objective used for the high-NA imaging may have significant influence on the acoustic force map in the probe chamber. We have characterized this influence experimentally and the findings were confirmed by model simulations. We show that it is possible to design the chamber and to choose the operating point in such a way as to avoid perturbations due to the objective lens. Moreover, we found that measuring the electrical impedance of the transducer provides an easy indicator for the acoustic resonances. PMID:27025398

  17. Three chamber negative ion source

    A negative ion vessel is divided into an excitation chamber, a negative ionization chamber and an extraction chamber by two magnetic filters. Input means introduces neutral molecules into a first chamber where a first electron discharge means vibrationally excites the molecules which migrate to a second chamber. In the second chamber a second electron discharge means ionizes the molecules, producing negative ions which are extracted into or by a third chamber. A first magnetic filter prevents high energy electrons from entering the negative ionization chamber from the excitation chamber. A second magnetic filter prevents high energy electrons from entering the extraction chamber from the negative ionizing chamber. An extraction grid at the end of the negative ion vessel attracts negative ions into the third chamber and accelerates them. Another grid, located adjacent to the extraction grid, carries a small positive voltage in order to inhibit positive ions from migrating into the extraction chamber and contour the plasma potential. Additional electrons can be suppressed from the output flux using ExB forces provided by magnetic field means and the extractor grid electric potential

  18. Large Eddy Simulation of thermoacoustic instabilities in annular combustion chambers

    Wolf, Pierre

    2011-01-01

    Increasingly stringent regulations and the need to tackle rising fuel prices have placed great emphasis on the design of aeronautical gas turbines. This drive towards innovation has resulted sometimes in new concepts being prone to combustion instabilities. Combustion instabilities arise from the coupling of acoustics and combustion. In the particular field of annular combustion chambers, these instabilities often take the form of azimuthal modes. To predict these modes, one must consider the...

  19. Scintillations in ionization chambers

    High purity Ar and mixtures of Ar with 1% CH4, 3% CH4, CO2 and N2, respectively, have been applied for fission fragment detection in a gridded ionization chamber. Gas scintillation has been observed simultaneously with a photomultiplier VALVO-XP 2041. Whereas all mixtures work equally well as an ionization gas, only Ar + 3% N2 shows a primary scintillation yield sufficient for fas timing. (orig.)

  20. Evaluation and Characterization Study of Dual Pulse Laser-Induced Spark (DPLIS) for Rocket Engine Ignition System Application

    Osborne, Robin; Wehrmeyer, Joseph; Trinh, Huu; Early, James

    2003-01-01

    This paper addresses the progress of technology development of a laser ignition system at NASA Marshall Space Flight Center (MSFC). Laser ignition has been used at MSFC in recent test series to successfully ignite RP1/GOX propellants in a subscale rocket chamber, and other past studies by NASA GRC have demonstrated the use of laser ignition for rocket engines. Despite the progress made in the study of this ignition method, the logistics of depositing laser sparks inside a rocket chamber have prohibited its use. However, recent advances in laser designs, the use of fiber optics, and studies of multi-pulse laser formats3 have renewed the interest of rocket designers in this state-of the-art technology which offers the potential elimination of torch igniter systems and their associated mechanical parts, as well as toxic hypergolic ignition systems. In support of this interest to develop an alternative ignition system that meets the risk-reduction demands of Next Generation Launch Technology (NGLT), characterization studies of a dual pulse laser format for laser-induced spark ignition are underway at MSFC. Results obtained at MSFC indicate that a dual pulse format can produce plasmas that absorb the laser energy as efficiently as a single pulse format, yet provide a longer plasma lifetime. In an experiments with lean H2/air propellants, the dual pulse laser format, containing the same total energy of a single laser pulse, produced a spark that was superior in its ability to provide sustained ignition of fuel-lean H2/air propellants. The results from these experiments are being used to optimize a dual pulse laser format for future subscale rocket chamber tests. Besides the ignition enhancement, the dual pulse technique provides a practical way to distribute and deliver laser light to the combustion chamber, an important consideration given the limitation of peak power that can be delivered through optical fibers. With this knowledge, scientists and engineers at Los

  1. Double chambered right ventricle

    Cho, Chul Koo; Yu, Yun Jeong; Yeon, Kyung Mo; Han, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1983-12-15

    Fourteen cases of double chambered right ventricle were diagnosed angiographically and of these nine cases were confirmed after operation and autopsy at Seoul National University Hospital in recent four years since 1979. The clinical and radiological findings with the emphasis on the cinecardiographic findings were analysed. The summaries of the analysis are as follows: 1. Among 14 cases, 6 cases were male and 8 cases were female. Age distribution was from 4 years to 36 years. 2. In chest x-ray findings, pulmonary vascularity was increased in 8 cases, decreased in 4 cases, and normal in 2 cases. Cardiomegaly was observed in 8 cases and other showed normal heart size. 3. In cinecardiography, 11 cases had interventricular septal defect. Among these 11 cases, VSD located in proximal high pressure chamber was in 2 cases and located in distal low pressure chamber was in 9 cases. 4. The location of aberrant muscle bundle in sinus portion of right ventricle was in 8 cases. In the rest 6 cases, the aberrant muscle bundle was located below the infundibulum of right ventricle. 5. For accurate diagnosis and differential diagnosis with other congenital cardiac anomalies such as Tetralogy of Fallot or isolated pulmonic stenosis, biplane cineangiography and catheterization is an essential procedure.

  2. Residual resistance simulation of an air spark gap switch

    Siahlo, S E

    2015-01-01

    The numerical simulation of an air spark gap has been carried within two theoretical models. The kinetic one [1] allowed us to calculate time dependencies for the residual resistance (0.2 - 0.4 Ohm for our selection of a circuit parameters), the spark gap channel width, the electron number density, the mobility, the conductivity, the ionization degree, the magnetic field in the discharge channel, the channel inductance and the electron drift velocity. Simulating a real circuit and taking into account a spark gap residual resistance demonstrates good agreement of both models with the experimental data, while that without taking into account this resistance overestimates the maximal current in the circuit by approximately 5%.

  3. A scaling method for combustion stability rating of coaxial gas liquid injectors in a subscale chamber

    A scaling method to examine combustion stability characteristics of a coaxial injector is devised based on the acoustics and combustion dynamics in a chamber. The method is required for a subscale test of stability rating with a model chamber, which is cost effective compared with an actual full scale test. First, scaling and similarity rules are considered for stability rating and thereby, three conditions of acoustic, hydrodynamic, and flame condition similarities are proposed. That is, for acoustic similarity, the natural or resonant frequencies in the actual chamber should be maintained in the model chamber. And, two parameters of density ratio and velocity ratio are derived for the requirement of hydrodynamic and flame condition similarities between the actual and the model conditions. Next, one example of an actual combustion chamber with high performance is selected and the proposed scaling method is applied to the chamber for understanding of the method. The design operating condition for a model test is presented by mass flow rates of propellants. Stability boundaries can be identified on the coordinate plane of chamber pressure and mixture ratio of fuel and oxidizer by applying the scaling method

  4. Practice and Exploration of New Rural Construction in West Bank of Taiwan Strait Led by Spark Science and Technology

    Li, Chaocan

    2013-01-01

    According to practice and exploration of spark program for 26 years in Quanzhou, the main model and their effects of new rural construction in west bank of Taiwan Strait led by spark science and technology were expounded. Six spark program systems were established, consisting of policy support guide, science and technology project lead, experts’ intelligence support, spark science and technology training, sci-tech information service and spark program demonstration. Five spark projects were...

  5. Process and device of spark mass spectrography analysis

    The invention relates to an analytical process by spark mass spectrography. Ions are created by discharge during sparking between two electrodes, the ions created are directed towards a mass spectrograph where spectrography is carried out. The feature of this process is that the spectrography is carried out only on the ions created by those discharges having a given direction. Preferably, under the invention, an electric excitation is applied to the electrodes through a circuit such that the discharges are critical or supercritical on damping

  6. Laser propagation and energy absorption by an argon spark

    Bindhu, C V; Harilal, S S; Tillack, M. S.; Najmabadi, F; Gaeris, A C

    2003-01-01

    The laser propagation and energy absorption of an argon spark induced by a laser at different pressures is investigated. 8 ns pulses from a frequency-doubled Q-switched Nd:YAG laser are used to create the spark. The pressure of the argon is varied from 1 atm to 10 Torr. Significant energy absorption by the plasma is observed at high pressures (>100 Torr) while there is negligible absorption when the pressure is lower than 50 Torr. The plasma kernel showed distinct behavior with respect to las...

  7. Plasma dynamics of a laser filamentation-guided spark

    Point, Guillaume; Carbonnel, Jérôme; Mysyrowicz, André; Houard, Aurélien

    2016-01-01

    We investigate experimentally the plasma dynamics of a centimeter-scale, laser filamentation-guided spark discharge. Using electrical and optical diagnostics to study monopolar discharges with varying current pulses we show that plasma decay is dominated by free electron recombination if the current decay time is shorter than the recombination characteristic time. In the opposite case, the plasma electron density closely follows the current evolution. We demonstrate that this criterion holds true in the case of damped AC sparks, and that alternative current is the best option to achieve a long plasma lifetime for a given peak current.

  8. A note on preserving the spark of a matrix

    Marcin Skrzynski

    2015-05-01

    Full Text Available Let Mm× n(F be the vector space of all m× n matrices over a field F. In the case where m ≥ n, char (F ≠ 2 and F has at least five elements, we give a complete characterization of linear maps Φ : Mm× n(F → Mm× n(F such that spark(Φ (A = spark(A for any A ∈ Mm× n(F.

  9. Analysis of Plant Breeding on Hadoop and Spark

    Shuangxi Chen

    2016-01-01

    Full Text Available Analysis of crop breeding technology is one of the important means of computer-assisted breeding techniques which have huge data, high dimensions, and a lot of unstructured data. We propose a crop breeding data analysis platform on Spark. The platform consists of Hadoop distributed file system (HDFS and cluster based on memory iterative components. With this cluster, we achieve crop breeding large data analysis tasks in parallel through API provided by Spark. By experiments and tests of Indica and Japonica rice traits, plant breeding analysis platform can significantly improve the breeding of big data analysis speed, reducing the workload of concurrent programming.

  10. Interaction of LOX/GH2-Spray Combustion with Acoustics

    Knapp, Bernhard; Farago, Zoltan; Oschwald, Michael

    2007-01-01

    The response of a cryogenic LOX/H2-spray flame to acoustic pressure and velocity fluctuations has be investigated experimentally for pressure levels up to p=1MPa. The dimensions of the combustion chamber are chosen to have transversal acoustic modes at eigenfrequencies representative to full scale rocket combustors. A siren wheel periodically opening a secondary nozzle was used to excite pressure oscillations in the cylindrical combustor at levels up to p'/p~10%. It has been found that the se...

  11. Vacuum Chambers for LEP sections

    1983-01-01

    The picture shows sections of the LEP vacuum chambers to be installed in the dipole magnets (left) and in the quadrupoles (right). The dipole chamber has three channels: the beam chamber, the pumping duct where the NEG (non-evaporabe getter) is installed and the water channel for cooling (on top in the picture). The pumping duct is connected to the beam chamber through holes in the separating wall. The thick lead lining to shield radiation can also be seen. These chambers were manufactured as extruded aluminium alloy profiles.

  12. An acoustical investigation of the concert harp

    Bell, Alexander J.

    1988-01-01

    This thesis is a report of acoustical research on the concert harp. The harp has an established place in the symphony orchestra and is reacquiring its role as a solo chamber instrument that it had before the development of the modern piano. As far as can be determined, this is the first doctoral thesis on the concert harp and serves as an introduction to the science of the instrument, The experimental methods employed- holographic interferonietry, input admittance measure...

  13. Acoustic hemostasis

    Crum, L.; Andrew, M.; Bailey, M.; Beach, K.; Brayman, A.; Curra, F.; Kaczkowski, P.; Kargl, S.; Martin, R.; Vaezy, S.

    2003-04-01

    Over the past several years, the Center for Industrial and Medical Ultrasound (CIMU) at the Applied Physics Laboratory in the University of Washington has undertaken a broad research program in the general area of High Intensity Focused Ultrasound (HIFU). Our principal emphasis has been on the use of HIFU to induce hemostasis; in particular, CIMU has sought to develop a small, lightweight, portable device that would use ultrasound for both imaging and therapy. Such a technology is needed because nearly 50% of combat casualty mortality results from exsanguinations, or uncontrolled bleeding. A similar percentage occurs for civilian death due to trauma. In this general review, a presentation of the general problem will be given, as well as our recent approaches to the development of an image-guided, transcutaneous, acoustic hemostasis device. [Work supported in part by the USAMRMC, ONR and the NIH.

  14. Acoustic telemetry.

    Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

    2003-08-01

    Broadcasting messages through the earth is a daunting task. Indeed, broadcasting a normal telephone conversion through the earth by wireless means is impossible with todays technology. Most of us don't care, but some do. Industries that drill into the earth need wireless communication to broadcast navigation parameters. This allows them to steer their drill bits. They also need information about the natural formation that they are drilling. Measurements of parameters such as pressure, temperature, and gamma radiation levels can tell them if they have found a valuable resource such as a geothermal reservoir or a stratum bearing natural gas. Wireless communication methods are available to the drilling industry. Information is broadcast via either pressure waves in the drilling fluid or electromagnetic waves in the earth and well tubing. Data transmission can only travel one way at rates around a few baud. Given that normal Internet telephone modems operate near 20,000 baud, these data rates are truly very slow. Moreover, communication is often interrupted or permanently blocked by drilling conditions or natural formation properties. Here we describe a tool that communicates with stress waves traveling through the steel drill pipe and production tubing in the well. It's based on an old idea called Acoustic Telemetry. But what we present here is more than an idea. This tool exists, it's drilled several wells, and it works. Currently, it's the first and only acoustic telemetry tool that can withstand the drilling environment. It broadcasts one way over a limited range at much faster rates than existing methods, but we also know how build a system that can communicate both up and down wells of indefinite length.

  15. Wire chambers revisited

    Multiwire proportional chambers (MWPCs) have long been used as position-sensitive charged particle detectors in nuclear and high-energy physics. MWPCs are large-area gas-filled ionisation chambers in which large arrays of fine wires are used to measure the position of ionisation produced in the gas by the passage of charged particles. The important properties of MWPCs are high-spatial-resolution, large-area, high-count-rate performance at low cost. For research applications, detectors several metres square have been built and small-area detectors have a charged particle resolution of 0.4 mm at a count rate of several million per second. Modification is required to MWPCs for nuclear medicine imaging. A gamma rays or X-rays cannot be detected directly, they must be converted into photo- or Compton scatter electrons. Photon-electron conversion requires the use of high atomic number materials in the body of the chamber. Pressurised xenon is the most useful form of ''gas only'' photon-electron convertor and has been used successfully in a gamma camera for the detection of gamma rays at energies below 100 keV. This camera has been developed specifically for high-count-rate first-pass cardiac imaging. This high-pressure xenon gas MWPC is the key to a highly competitive system which can outperform scintillator-based systems. The count rate performance is close to a million counts per second and the intrinsic spatial resolution is better than the best scintillator-based camera.The only clinical detector have been developed for positron emission tomography, where thin lead or lead-glass can provide an acceptable convertor for 511 keV photons. Two MWPC positron cameras have been evaluated clinically and one is now routine use in clinical oncology. The problems of detection efficiency have not been solved by these detectors although reliability and large-area PET imaging have been proven. (orig./HSI)

  16. Acoustic Neuroma Educational Video

    Full Text Available Educational Video Home What is an AN What is an Acoustic Neuroma? Identifying an AN Symptoms Acoustic Neuroma Keywords Educational Video ... for pre- and post-treatment acoustic neuroma patients. Home What is an AN What is an Acoustic ...

  17. Acoustic metamaterial with negative modulus and a double negative structure

    Sharma, Bhisham; Sun, Chin-teh

    2015-01-01

    An acoustic negative bulk modulus metamaterial based on the concept of expansion chambers is proposed. It is shown that addition of a neck region to an ordinary expansion chamber improves its transmission loss characteristics at low frequencies and the resulting structure displays a negative bulk modulus behavior. Additionally, membrane based metamaterials are analyzed. Using FEM, the negative density behavior of a membrane carrying a center mass and of a tensioned membrane array is analyzed ...

  18. Research on acoustic fatigue experimental models of the dryer in steam generators

    Background: When upgrading the reactor power to promote the power efficiency of nuclear power plants, the BWR steam dryer is easier to be damaged by high cycle pulsating pressure, which is called acoustic fatigue problem. Purpose: An acoustic fatigue experimental schemes in steam generators is designed to study the acoustic load on the steam dryer. Methods: The acoustical computational software ACTRAN has been applied to simulate the acoustic pressure distribution inside scaled model of the upper chamber of steam generators. Results: Sound pressure level contour distributions at different frequencies are predicted. Conclusions: Sound pressure level contour distribution at mid-frequency is heterogeneous which is different with the low frequency one. (authors)

  19. 40 CFR Appendix II to Part 1048 - Large Spark-ignition (SI) Composite Transient Cycle

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Large Spark-ignition (SI) Composite... (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM NEW, LARGE NONROAD SPARK-IGNITION ENGINES Pt. 1048, App. II Appendix II to Part 1048—Large Spark-ignition (SI) Composite Transient Cycle...

  20. Use of acoustic vortices in acoustic levitation

    Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...

  1. Review of wire chamber aging

    This paper makes an overview of the wire chamber aging problems as a function of various chamber design parameters. It emphasizes the chemistry point of view and many examples are drawn from the plasma chemistry field as a guidance for a possible effort in the wire chamber field. The paper emphasizes the necessity of variable tuning, the importance of purity of the wire chamber environment, as well as it provides a practical list of presently known recommendations. In addition, several models of the wire chamber aging are qualitatively discussed. The paper is based on a summary talk given at the Wire Chamber Aging Workshop held at LBL, Berkeley on January 16-17, 1986. Presented also at Wire Chamber Conference, Vienna, February 25-28, 1986. 74 refs., 18 figs., 11 tabs

  2. CFD Analysis of in-Cylinder Flow and Air-Fuel Interaction on Different Combustion Chamber Geometry in DISI Engine

    B. Harshavardhan; Mallikarjuna, J. M.

    2013-01-01

    In this investigation, a CFD analysis has been carried out on in-cylinder fluid flows and air-fuel interaction in Direct Injection Spark Ignition (DISI) engine by changing combustion chamber geometry during intake and compression stroke at an engine speed of 1500 rpm for four different types of piston profiles viz., flat piston, flat piston with centre bowl, dome piston with centre bowl and pentroof offset bowl piston. A polyhedral trimmed cell has been taken for meshing of the geometries usi...

  3. Mass spectrometry and mass spectrography with spark source

    The analysis of geological materials for traces of elements can be performed using mass-spectrometric isotopic dilution, as well as mass-spectrography with a spark source. The review contains the data on the application of above analyses in geochemical analysis

  4. Joining of β-SiC by spark plasma sintering

    Grasso, S.; Tatarko, Peter; Rizzo, S.; Porwal, H.; Hu, Ch.; Katoh, Y.; Salvo, M.; Reece, M. J.; Ferraris, M.

    2014-01-01

    Roč. 34, č. 7 (2014), s. 1681-1686. ISSN 0955-2219 EU Projects: European Commission(XE) 264526 - GLACERCO Institutional support: RVO:68081723 Keywords : β-SiC * joining * Spark plasma sintering Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.947, year: 2014

  5. Enrichment of colloidal solutions by nanoparticles in underwater spark discharge

    The underwater spark discharge between manganese granules was studied. Optical emission spectroscopy methods were used for diagnostics of such discharge plasma. The colloidal solution with manganese nanoparticles was produced by this discharge. The biological applications of this colloid were analyzed. The mechanism of metallic nanoparticle action and their transformation at interacting with biological objects were studied in Alternaria alternata culture

  6. Spark RttT: Year One Fidelity and Implementation

    Rochford, Joseph A.; O'Neill, Adrienne; Gelb, Adele; Ross, Kimberly

    2014-01-01

    Developed in 2003 by the Sisters of Charity Foundation of Canton with a grant from the Kellogg Foundation, "Supporting Partnerships to Assure Ready Kids" ("SPARK Ohio") is a family-centered kindergarten readiness program that works with families, schools, and the community. From its initial sites in Stark County, "SPARK…

  7. Meter-scale spark X-ray spectrumstatistics

    Carlson, B E; Kochkin, P; Grondahl, Ø; Nisi, R; Weber, K; Scherrer, Z; LeCaptain, K

    2016-01-01

    X-ray emission by sparks implies bremsstrahlung from a population of energetic electrons, but the details of this process remain a mystery. We present detailed statistical analysis of X-ray spectra detected by multiple detectors during sparks produced by 1 MV negative high-voltage pulses with 1 $\\mu$s risetime. With over 900 shots, we statistically analyze the signals, assuming that the distribution of spark X-ray fluence behaves as a power law and that the energy spectrum of X-rays detectable after traversing $\\sim$2 m of air and a thin aluminum shield is exponential. We then determine the parameters of those distributions by fitting cumulative distribution functions to the observations. The fit results match the observations very well if the mean of the exponential X-ray energy distribution is 86 $\\pm$ 7 keV and the spark X-ray fluence power law distribution has index -1.29 $\\pm$ 0.04 and spans at least 3 orders of magnitude in fluence.

  8. Use of SPARK to Promote After-School Physical Activity

    Herrick, Heidi; Thompson, Hannah; Kinder, Jennifer; Madsen, Kristine A.

    2012-01-01

    Background: The after-school period is potentially an important venue for increasing physical activity for youth. We sought to assess the effectiveness of the Sports, Play, and Recreation for Youth (SPARK) program to increase physical activity and improve cardiorespiratory fitness and weight status among elementary students after school. Methods:…

  9. Study of spark gap switch for crowbar circuit

    A compact and low cost 3-electrode spark gap switch, SAMTECH PCS (T)-01, was tested in considering its use as a crowbar switch of the high voltage DC power supply for ILC (International Linear Collider) modulating anode klystron. The result showed an expected performance, but its life time was shorter than we expected. Further R and D is under way. (author)

  10. Acoustic dispersive prism

    Hussein Esfahlani; Sami Karkar; Herve Lissek; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic ...