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1

Method for calibrating a Rogowski coil of fast time response  

Science.gov (United States)

A new method was designed for calibrating a Rogowski coil of fast time response. The method is based on the cable pulser method except that the voltage signal pick-off output was moved to a position with a distance l from the load. If 2l/v is longer than the time duration of the forward voltage pulse uf(t), the reflected voltage pulse ur(t) could be separated from uf(t) and directly measured. Using the formula i(t )=[uf(t)-ur(t)]/50 to calculate the primary current of the Rogowski coil, the coil could be more accurately calibrated.

Liu, Rui; Wang, Xinxin; Zou, Xiaobing; Yuan, Jianqiang; Zou, Naigong; He, Luya

2007-08-01

2

Fast-Response-Time Shape-Memory-Effect Foam Actuators  

Science.gov (United States)

Bulk shape memory alloys, such as Nitinol or CuAlZn, display strong recovery forces undergoing a phase transformation after being strained in their martensitic state. These recovery forces are used for actuation. As the phase transformation is thermally driven, the response time of the actuation can be slow, as the heat must be passively inserted or removed from the alloy. Shape memory alloy TiNi torque tubes have been investigated for at least 20 years and have demonstrated high actuation forces [3,000 in.-lb (approximately equal to 340 N-m) torques] and are very lightweight. However, they are not easy to attach to existing structures. Adhesives will fail in shear at low-torque loads and the TiNi is not weldable, so that mechanical crimp fits have been generally used. These are not reliable, especially in vibratory environments. The TiNi is also slow to heat up, as it can only be heated indirectly using heater and cooling must be done passively. This has restricted their use to on-off actuators where cycle times of approximately one minute is acceptable. Self-propagating high-temperature synthesis (SHS) has been used in the past to make porous TiNi metal foams. Shape Change Technologies has been able to train SHS derived TiNi to exhibit the shape memory effect. As it is an open-celled material, fast response times were observed when the material was heated using hot and cold fluids. A methodology was developed to make the open-celled porous TiNi foams as a tube with integrated hexagonal ends, which then becomes a torsional actuator with fast response times. Under processing developed independently, researchers were able to verify torques of 84 in.-lb (approximately equal to 9.5 Nm) using an actuator weighing 1.3 oz (approximately equal to 37 g) with very fast (less than 1/16th of a second) initial response times when hot and cold fluids were used to facilitate heat transfer. Integrated structural connections were added as part of the net shape process, eliminating the need for welding, adhesives, or mechanical crimping. Inexpensive net-shape processing was used, which reduces the cost of the actuator by over a factor of 10 over nonporous TiNi made by hot drawing of tube or electrical discharge machining. By forming the alloy as an open-celled foam, the surface area for heat transfer is dramatically increased, allowing for much faster response times. The technology also allows for netshape fabrication of the actuator, which allows for structural connections to be integrated into the actuator material, making these actuators significantly less expensive. Commercial applications include actuators for concepts such as the variable area chevron and nozzle in jet aircraft. Lightweight tube or rod components can be supplied to interested parties.

Jardine, Peter

2010-01-01

3

Study of the time response of a LuAG(Pr) crystal for fast timing applications  

Energy Technology Data Exchange (ETDEWEB)

The recently developed praseodymium-doped lutetium aluminum garnet, LuAG(Pr), holds a strong potential for fast timing applications. In this study we report on the time response of LuAG(Pr) at {sup 22}Na and {sup 60}Co photon energies. The measurements were performed using a small crystal cube of 1 cm{sup 3} coupled to a Hamamatsu R5320 photomultiplier tube. The full width at half maximum (FWHM) time resolution is found to be 147±2 ps at {sup 60}Co energies, and 238±2 ps at {sup 22}Na.

Fraile, L.M., E-mail: fraile@nuc2.fis.ucm.es [Grupo de Física Nuclear, Facultad de CC. Físicas, Universidad Complutense, CEI Moncloa, 28040 Madrid (Spain); Mach, H. [Grupo de Física Nuclear, Facultad de CC. Físicas, Universidad Complutense, CEI Moncloa, 28040 Madrid (Spain); Picado, E.; Vedia, V.; Udías, J.M. [Grupo de Física Nuclear, Facultad de CC. Físicas, Universidad Complutense, CEI Moncloa, 28040 Madrid (Spain)

2013-06-11

4

Four-domain twisted nematic structure with enhanced liquid crystal alignment stability and fast response time  

Science.gov (United States)

In this paper, we propose a stable four-domain twisted nematic structure with wide viewing angle characteristics and a fast response time. A stable structure was realized by introducing a high pre-tilt angle approach incorporating stacked planar and vertical alignment layers. The response time and thermal stability of the proposed device were dramatically improved by the addition of UV-curable reactive mesogen (RM) mixed with a vertical alignment material. Polymerized RMs along the liquid crystal (LC) director increased the polar anchoring energy and reduced back-flow phenomena. A wide viewing angle and fast response time characteristics were achieved over all gray levels.

Moon, Yeon-Kyu; Lee, You-Jin; Yu, Chang-Jae; Uk Heo, Jeong; Park, Jae-Hong; jin Lee, Hyeok; Tae Shin, Sung; Kim, Jae-Hoon

2012-07-01

5

Time response of fast-gated microchannel plates used as x-ray detectors  

International Nuclear Information System (INIS)

We report measurements of the time response of fast-gated, micro- channel plate (MCP) detectors, using a <10 ps pulsewidth ultra-violet laser and an electronic sampling system to measure time resolutions to better than 25 ps. The results show that framing times of less than 100 ps are attainable with high gain. The data is compared to a Monte Carlo calculation, which shows good agreement. We also measured the relative sensitivity as a function of DC bias, and saturation effects for large signal inputs. In part B, we briefly describe an electrical ''time-of-flight'' technique, which we have used to measure the response time of a fast-gated microchannel plate (MCP). Thinner MCP's than previously used have been tested, and, as expected, show fast gating times and smaller electron multiplication. A preliminary design for an x-ray pinhole camera, using a thin MCP, is presented. 7 refs., 6 figs

6

Wide dynamic range neutron flux monitor having fast time response for the Large Helical Device.  

Science.gov (United States)

A fast time response, wide dynamic range neutron flux monitor has been developed toward the LHD deuterium operation by using leading-edge signal processing technologies providing maximum counting rate up to ?5 × 10(9) counts/s. Because a maximum total neutron emission rate over 1 × 10(16) n/s is predicted in neutral beam-heated LHD plasmas, fast response and wide dynamic range capabilities of the system are essential. Preliminary tests have demonstrated successful performance as a wide dynamic range monitor along the design. PMID:25430293

Isobe, M; Ogawa, K; Miyake, H; Hayashi, H; Kobuchi, T; Nakano, Y; Watanabe, K; Uritani, A; Misawa, T; Nishitani, T; Tomitaka, M; Kumagai, T; Mashiyama, Y; Ito, D; Kono, S; Yamauchi, M; Takeiri, Y

2014-11-01

7

Wide dynamic range neutron flux monitor having fast time response for the Large Helical Devicea)  

Science.gov (United States)

A fast time response, wide dynamic range neutron flux monitor has been developed toward the LHD deuterium operation by using leading-edge signal processing technologies providing maximum counting rate up to ˜5 × 109 counts/s. Because a maximum total neutron emission rate over 1 × 1016 n/s is predicted in neutral beam-heated LHD plasmas, fast response and wide dynamic range capabilities of the system are essential. Preliminary tests have demonstrated successful performance as a wide dynamic range monitor along the design.

Isobe, M.; Ogawa, K.; Miyake, H.; Hayashi, H.; Kobuchi, T.; Nakano, Y.; Watanabe, K.; Uritani, A.; Misawa, T.; Nishitani, T.; Tomitaka, M.; Kumagai, T.; Mashiyama, Y.; Ito, D.; Kono, S.; Yamauchi, M.; Takeiri, Y.

2014-11-01

8

Polymer-stabilized liquid crystal microlens array with large dynamic range and fast response time.  

Science.gov (United States)

We report a polymer-stabilized liquid crystal (LC) microlens array with a large dynamic range and fast response time. The top substrate has a planar indium-tin oxide (ITO) electrode, while the bottom substrate has two patterned ITO electrodes for generating a fringing field and uniform longitudinal field. The fringing field is utilized to create the desired gradient refractive index profile in the LC/monomer layer, which is later stabilized by UV curing to form polymer networks. To tune the focal length, we apply a longitudinal field to change the lens shape. This microlens array offers several attractive features, such as large dynamic range, fast response time, and good mechanical stability. PMID:24104671

Ren, Hongwen; Xu, Su; Wu, Shin-Tson

2013-08-15

9

Variable optical attenuator using thermo-optic two-mode interference device with fast response time.  

Science.gov (United States)

A thermo-optic two-mode interference (TMI) waveguide structure with a silicon trench and heat-insulating grooves in both sides of the core has been proposed for a variable optical attenuator (VOA) with fast response time. Thermal analysis of the proposed thermo-optic TMI waveguide structure with a silicon oxinitride (SiON) core has been performed by using the implicit finite difference method. The heating power required to achieve the attenuated power of approximately -25.5 dB for a VOA with a silicon trench is 460 mW , which is approximately 1.8 times less than that of a VOA without a silicon trench. The response time is estimated as approximately 98 micros, which is faster than the response time of the existing VOA. PMID:19623235

Sahu, Partha P

2009-07-20

10

Time-Dependent Modeling of Nonlinear Plasma Response to Fast Waves With Multiple Damping Mechanisms  

Science.gov (United States)

Recent DIII-D experiments on the absorption of fast waves (FWs) by moderate to high ion cyclotron harmonic damping [R. I. Pinsker, et al., Nucl. Fusion 46, S416-S424 (2006)] have motivated a substantial modeling effort within the RF SciDAC community, but as of yet, the time dependence of the plasma response has not been modeled. In this work, a simple 0-D time-dependent absorption and transport model is used to predict the plasma response to a step in FW power when multiple FW absorption mechanisms are present. When the plasma has a nonlinear response to at least one of the damping mechanisms, both the partition between the various absorption channels in the steady-state solution and the time required to reach the final state depend strongly on the initial conditions.

Pinsker, R. I.

2007-09-01

11

Timing and position response of a block detector for fast neutron time-of-flight imaging  

Science.gov (United States)

Our research effort seeks to improve the spatial and timing performance of a block detector made of a pixilated plastic scintillator (EJ-200), first demonstrated as part of Oak Ridge National Laboratory's Advanced Portable Neutron Imaging System. Improvement of the position and time response is necessary to achieve better resolution and contrast in the images of shielded special nuclear material. Time-of-flight is used to differentiate between gamma and different sources of neutrons (e.g., transmission and fission neutrons). Factors limiting the timing and position performance of the neutron detector have been revealed through simulations and measurements. Simulations have suggested that the degradation in the ability to resolve pixels in the neutron detector is due to those interactions occurring near the light guide. The energy deposition within the neutron detector is shown to affect position performance and imaging efficiency. This examination details how energy cuts improve the position performance and degrade the imaging efficiency. Measurements have shown the neutron detector to have a timing resolution of ?=238 ps. The majority of this timing uncertainty is from the depth-of-interaction (DOI) of the neutron which is confirmed by simulations and analytical calculations.

Laubach, M. A.; Hayward, J. P.; Zhang, X.; Cates, J. W.

2014-11-01

12

Real-time Holographic Display Based on a Super Fast Response Thin Film  

International Nuclear Information System (INIS)

Real-time dynamic holographic display is obtained with super fast response in a thin film without any applied electric field. Holograms can be refreshed in the order of a millisecond and there is no cross talk between the recorded holograms because the hologram formed in the film is transient and can be completely self erased, and the hologram formation time and self-erasure time are both ?1 ms. Holographic video display is achieved, which shows the real-time holographic image display capability of the thin film, and its much higher resolution than those of commercially available spatial light modulators. Furthermore, multiplexed hologram display using two polarization directions of a recorded light and multiple color holographic display at different laser wavelengths are presented, which demonstrate the feasibility of a RGB color holographic three-dimensional display with the thin film. Because the sample is easy to be fabricated into a large size screen and needs no external applied electric field, we think that the film can be developed into a large-size, dynamic, and color holographic three-dimensional display in the future.

13

Characterizing a fast-response, low-afterglow liquid scintillator for neutron time-of-flight diagnostics in fast ignition experimentsa)  

Science.gov (United States)

The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer for fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better characteristics as a liquid scintillator solvent than the conventional solvent, p-xylene. In addition, a benzophenon-doped BBQ liquid scintillator is shown to demonstrate very rapid time response, and therefore has potential for further use in neutron diagnostics with fast time resolution.

Abe, Y.; Hosoda, H.; Arikawa, Y.; Nagai, T.; Kojima, S.; Sakata, S.; Inoue, H.; Iwasa, Y.; Iwano, K.; Yamanoi, K.; Fujioka, S.; Nakai, M.; Sarukura, N.; Shiraga, H.; Norimatsu, T.; Azechi, H.

2014-11-01

14

Time-resolved entropy measurements using a fast response entropy probe  

Science.gov (United States)

This paper describes a recently developed miniature fast response entropy probe and its application in the turbomachinery facilities at ETH Zurich. The development of the probe is motivated by the need to more clearly document the loss generation mechanisms in the harsh environment of turbomachines. The probe is comprised of a piezoresistive sensor and a pair of thin-film gauges that measure the unsteady pressure and temperature, respectively. The unsteady relative entropy can thus be determined. The design, manufacture and calibration of the probe are first presented in detail. Its application to detail the unsteady entropy field, and associated losses, in a centrifugal compressor, axial turbine and film cooling flows are then described.

Mansour, Michel; Chokani, Ndaona; Kalfas, Anestis I.; Abhari, Reza S.

2008-11-01

15

A direct indication of plasma potential diagnostic with fast time response and high accuracy based on a differential emissive probe  

International Nuclear Information System (INIS)

The floating potential of the emissive probe has been used to directly measure the plasma potential. The authors have recently presented another method for directly indicating the plasma potential with a differential emissive probe. In this paper they describe the effects of probe size, plasma density and plasma potential fluctuation on plasma potential measurements and give methods for reducing errors. A control system with fast time response (? 20 ?s) and high accuracy (the order of the probe temperature T/sub w//e) for maintaining a differential emissive probe at plasma potential has been developed. It can be operated in pulsed discharge plasma to measure plasma potential dynamic characteristics. A solid state optical coupler is employed to improve circuit performance. This system was tested experimentally by measuring the plasma potential in an argon plasma device and on the Phaedrus tandem mirror

16

Fast-response pulsed manometer  

International Nuclear Information System (INIS)

Fast-response pulsed manometer for measuring 10?s-500?s pulses of gas pressure is described. The PMI-10-2 ionization manometric transducer is used as pressure gauge. The range of measured pressures is 10-3-102 Pa

17

Fast water oil spill response  

International Nuclear Information System (INIS)

Of the many manuals currently available for oil spill response, few have any information on fast-water conditions even though just more than half of all oil spilled by volume in the United States between 1992 and 1997 happened in waterways with currents exceeding one knot. The Coast Guard recognized the absence of standard terminology that could be used for fast-water responses. For that reason, an initiative was undertaken to create a document that addresses only fast-water issues. Two major parts of the project were to provide information on deployment strategies and techniques to identify equipment that could improve recovery capabilities where existing systems do not work well. This paper described field demonstrations where boom deflectors and boom vanes were used. Efforts to increase the capability of booms and skimmers were also described. A field guide was developed for training and response purposes for spills in fast-water which makes it possible for on-scene commanders and area supervisors to define techniques and terminology for responders in the field. It is particularly useful for Coast Guard Marine Safety Units when working with Coast Guard operational units during an emergency response. 20 refs., 4 figs

18

Fast response time of fringe-field switching liquid crystal mode devices with reactive mesogens in a planar alignment layer  

Science.gov (United States)

We report the response time of fringe-field switching (FFS) liquid crystal (LC) mode devices using an ultraviolet-curable reactive mesogen (RM) mixed in a planar alignment layer. The RM polymers within the alignment layer increase the surface azimuthal anchoring energy and the order parameter of the LC molecules. As a result, the falling time and the rising time in the FFS mode are improved by the enhanced azimuthal anchoring energy and the increased dielectric torque induced by higher order parameter of LCs.

Kim, Youngsik; Lee, You-Jin; Kim, Dong-Ha; Baek, Ji-Ho; Lee, Joun-Ho; Kim, Byeong-Koo; Yu, Chang-Jae; Kim, Jae-Hoon

2013-12-01

19

The time-walk of analog constant fraction discriminators using very fast scintillator detectors with linear and non-linear energy response  

Energy Technology Data Exchange (ETDEWEB)

The electronic {gamma}-{gamma} fast timing technique allows for direct nuclear lifetime determination down to the few picoseconds region by measuring the time difference between two coincident {gamma}-ray transitions. Using high resolution ultra-fast LaBr{sub 3}(Ce) scintillator detectors in combination with the recently developed mirror symmetric centroid difference method, nuclear lifetimes are measured with a time resolving power of around 5 ps. The essence of the method is to calibrate the energy dependent position (centroid) of the prompt response function of the setup which is obtained for simultaneously occurring events. This time-walk of the prompt response function induced by the analog constant fraction discriminator has been determined by systematic measurements using different photomultiplier tubes and timing adjustments of the constant fraction discriminator. We propose a universal calibration function which describes the time-walk or the combined {gamma}-{gamma} time-walk characteristics, respectively, for either a linear or a non-linear amplitude versus energy dependency of the scintillator detector output pulses.

Regis, J.-M., E-mail: regis@ikp.uni-koeln.de [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany); Rudigier, M.; Jolie, J.; Blazhev, A.; Fransen, C.; Pascovici, G.; Warr, N. [Institut fuer Kernphysik der Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany)

2012-08-21

20

Enhanced Photoacoustic Gas Analyser Response Time and Impact on Accuracy at Fast Ventilation Rates during Multiple Breath Washout  

Science.gov (United States)

Background The Innocor device contains a highly sensitive photoacoustic gas analyser that has been used to perform multiple breath washout (MBW) measurements using very low concentrations of the tracer gas SF6. Use in smaller subjects has been restricted by the requirement for a gas analyser response time of <100 ms, in order to ensure accurate estimation of lung volumes at rapid ventilation rates. Methods A series of previously reported and novel enhancements were made to the gas analyser to produce a clinically practical system with a reduced response time. An enhanced lung model system, capable of delivering highly accurate ventilation rates and volumes, was used to assess in vitro accuracy of functional residual capacity (FRC) volume calculation and the effects of flow and gas signal alignment on this. Results 10–90% rise time was reduced from 154 to 88 ms. In an adult/child lung model, accuracy of volume calculation was ?0.9 to 2.9% for all measurements, including those with ventilation rate of 30/min and FRC of 0.5 L; for the un-enhanced system, accuracy deteriorated at higher ventilation rates and smaller FRC. In a separate smaller lung model (ventilation rate 60/min, FRC 250 ml, tidal volume 100 ml), mean accuracy of FRC measurement for the enhanced system was minus 0.95% (range ?3.8 to 2.0%). Error sensitivity to flow and gas signal alignment was increased by ventilation rate, smaller FRC and slower analyser response time. Conclusion The Innocor analyser can be enhanced to reliably generate highly accurate FRC measurements down at volumes as low as those simulating infant lung settings. Signal alignment is a critical factor. With these enhancements, the Innocor analyser exceeds key technical component recommendations for MBW apparatus. PMID:24892522

Horsley, Alex; Macleod, Kenneth; Gupta, Ruchi; Goddard, Nick; Bell, Nicholas

2014-01-01

 
 
 
 
21

Standing variation and new mutations both contribute to a fast response to selection for flowering time in maize inbreds  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background In order to investigate the rate and limits of the response to selection from highly inbred genetic material and evaluate the respective contribution of standing variation and new mutations, we conducted a divergent selection experiment from maize inbred lines in open-field conditions during 7 years. Two maize commercial seed lots considered as inbred lines, F252 and MBS847, constituted two biological replicates of the experiment. In each replicate, we derived an Early and a Late population by selecting and selfing the earliest and the latest individuals, respectively, to produce the next generation. Results All populations, except the Early MBS847, responded to selection despite a short number of generations and a small effective population size. Part of the response can be attributed to standing genetic variation in the initial seed lot. Indeed, we identified one polymorphism initially segregating in the F252 seed lot at a candidate locus for flowering time, which explained 35% of the trait variation within the Late F252 population. However, the model that best explained our data takes into account both residual polymorphism in the initial seed lots and a constant input of heritable genetic variation by new (epimutations. Under this model, values of mutational heritability range from 0.013 to 0.025, and stand as an upper bound compare to what is reported in other species. Conclusions Our study reports a long-term divergent selection experiment for a complex trait, flowering time, conducted on maize in open-field conditions. Starting from a highly inbred material, we created within a few generations populations that strikingly differ from the initial seed lot for flowering time while preserving most of the phenotypic characteristics of the initial inbred. Such material is unique for studying the dynamics of the response to selection and its determinants. In addition to the fixation of a standing beneficial mutation associated with a large phenotypic effect, a constant input of genetic variance by new mutations has likely contributed to the response. We discuss our results in the context of the evolution and mutational dynamics of populations characterized by a small effective population size.

Ressayre Adrienne

2010-01-01

22

Fast response stainless steel sodium thermocouple  

International Nuclear Information System (INIS)

Thermo electro motive force and transient response characteristics of well-type stainless steel sodium thermocouples have been studied. The experiments were performed with a specially constructed test rig allowing the placement of several couples at various depths of immersion in liquid sodium and at different spacings. The time response was studied by inducing temperature transients in a hot sodium injection and gas injection, and photographing the oscilloscope trace of the output. The possibility of using these thermocouples in transit time flowmeters in sodium circuit was ascertained by observing the response from two thermocouples in flowing sodium, and evaluating the cross-correlation between the response. The application of such thermocouples for fast reactors and sodium circuits is also discussed. (author)

23

Fast-Response Liquid Crystal Microlens  

Directory of Open Access Journals (Sweden)

Full Text Available Electrically tunable liquid crystal microlenses have attracted strong research attention due to their advantages of tunable focusing, voltage actuation, low power consumption, simple fabrication, compact structure, and good stability. They are expected to be essential optical devices with widespread applications. However, the slow response time of nematic liquid crystal (LC microlenses has been a significant technical barrier to practical applications and commercialization. LC/polymer composites, consisting of LC and monomer, are an important extension of pure LC systems, which offer more flexibility and much richer functionality than LC alone. Due to the anchoring effect of a polymer network, microlenses, based on LC/polymer composites, have relatively fast response time in comparison with pure nematic LC microlenses. In addition, polymer-stabilized blue phase liquid crystal (PS-BPLC based on Kerr effect is emerging as a promising candidate for new photonics application. The major attractions of PS-BPLC are submillisecond response time and no need for surface alignment layer. In this paper, we review two types of fast-response microlenses based on LC/polymer composites: polymer dispersed/stabilized nematic LC and polymer-stabilized blue phase LC. Their basic operating principles are introduced and recent progress is reviewed by examples from recent literature. Finally, the major challenges and future perspectives are discussed.

Su Xu

2014-06-01

24

Reducing preoperative fasting time: A trend based on evidence  

Directory of Open Access Journals (Sweden)

Full Text Available Preoperative fasting is mandatory before anesthesia to reduce the risk of aspiration. However, the prescribed 6-8 h of fasting is usually prolonged to 12-16 h for various reasons. Prolonged fasting triggers a metabolic response that precipitates gluconeogenesis and increases the organic response to trauma. Various randomized trials and meta-analyses have consistently shown that is safe to reduce the preoperative fasting time with a carbohydrate-rich drink up to 2 h before surgery. Benefits related to this shorter preoperative fasting include the reduction of postoperative gastrointestinal discomfort and insulin resistance. New formulas containing amino acids such as glutamine and other peptides are being studied and are promising candidates to be used to reduce preoperative fasting time.

José Eduardo de Aguilar-Nascimento

2010-03-01

25

Short-Time-Response measurements of nitrogen dioxide and peroxyacetyl nitrate by fast capillary gas chromatography with luminol detection.  

Energy Technology Data Exchange (ETDEWEB)

The interaction of hydrocarbons and nitrogen oxides in sunlight to produce photochemical smog has been well studied over the years. In the past, the workhorse for the measurement of NO{sub 2}and NO was the chemiluminescent reaction with ozone. This method has detection limits of approximately 0.5 ppb in most commercial instruments, but it cannot detect NO{sub 2} directly; the instrument detects NO and uses hot catalytic surfaces to decompose all other nitrogen oxides (including NO{sub 2}) to NO for detection (l). The main problem with the method is the inherent difficulty in detecting excited NO{sub 2}, which emits over a broad region beginning at approximately 660 nm and has a maximum at 1270 nm, thus requiring a red-shifted photomultiplier for detection. The use of luminol for direct chemiluminescent detection of NO{sub 2} was demonstrated to have greater inherent sensitivity (detection limits of 5 ppt) than the indirect ozone chemiluminescence detection (2). In the luminol system, a gas-liquid reaction leads to light emission with a maximum at approximately 425 nm, at the maximum sensitivity for most photomultiplier tubes. This emission is responsible for the increased detection sensitivities. The biggest problem with this method for direct measurement of NO{sub 2} has been interference due to other soluble oxidants, particularly peroxyacyl nitrates (PANs).

Marley, N. A.; Gaffney, J. S.; Drayton, P. J.

2000-12-07

26

Fast-response sensors for dissolved oxygen  

Science.gov (United States)

In this work we have been developing fast response optical sensors for dissolved oxygen determination based on measuring the luminescence lifetime of a metalloporphyrin polymer. The sensor is produced by electropolymerization of the metalloporphyrin monomer units of platinum tetraphenylporphyrin (Pt-TPP), platinum octaethylporphyrin (Pt-OEP), palladium tetraphenylporphyrin (Pd-TPP) or palladium octaethylporphyrin (Pd-OEP). The polymerization process results in films which are in the region of micrometers thick. The Stern-Volmer quenching constants as determined from luminescence lifetime measurements for these sensors range from 0.90 (mg 1-1)-1) for Pt-TPP to 1.83 (mg 1-1)-1) for Pd-OEP. The response time of these sensors to a step change from an oxygen free to an oxygen saturated solution is in the millisecond region.

Smith, Sheila; Hamill, Alan; Uttamlal, Mahesh; Campbell, Michael; Bailly, David

1999-12-01

27

LCD response time estimation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Techniques to reduce LCD motion blur are extensively used in industry and they depend on an inherent LCD parameter: response time. However, normative response time is not a sufficient reference to improve LCD performance. Rather, all the gray-to-gray response times quantities are required to obtain a good improvement quality. Consequently, we propose a novel LCD model to simulate as well as compute gray-to-gray transitions (response time and behavior) from a reduced measurement set.

2006-01-01

28

Wisconsin Fast Plants Life Cycle Time Lapse  

Science.gov (United States)

On YouTube: Time lapse video of Wisconsin Fast Plants growing from planted seed through flowering to seed production, set to music!Time lapse just makes them grow a little faster than they do in real life -- this video shows approximately 40 days, the time it takes to produce the next generation.

29

Pembina spill response fast and effective  

International Nuclear Information System (INIS)

A break in a pipeline carrying light crude between Taylor and Prince George, British Columbia, occurred on Aug 1, 2000. The drop in pressure was first noted at the Federated Pipelines' control room in Calgary at 1.38 AM. The break was located within an hour. Within minutes of confirmation, the valves were closed upstream and downstream of the leak and spill response teams, equipment and Pembina officials were en route to the site, approximately 100 kms from the nearest town. By mid-afternoon of the same day three containment booms were in place and oil was already being pumped out of the river into a fleet of vacuum trucks. By Aug 4, the spill was fully contained and cleanup operations underway. At the peak of the containment operation about 40 pipeline employees and about 100 contractors and other responders were on the scene. An estimated one million litres of crude oil were released into the river; recovery operations were still in progress at press time. A post-incident review of the spill and containment efforts found that response was as fast and as well coordinated as could have been expected considering the night-time conditions. The B.C. Oil and Gas Commission considered the pipeline company's response excellent, and was also impressed by the cooperation among various pipeline companies and contractors. The break was eventually identified as a split in the lamination where two pipe edges join, a condition that cannot be detected in advance by present day technology. 1 map., 1 photo

30

Fast trigger logic with digitized time information  

CERN Document Server

We present a method for the evaluation, at the first level of trigger, of logical conditions with high time resolution, using the digitized times of fast signals delivered in the detectors of high rate experiments. We describe a dead-time-less implementation of this method on a commercial Field Programmable Gate Array (FPGA). By virtue of its features, the method offers an excellent solution to the problem of including veto conditions in the first level of trigger for experiments on rare decays.

Imbergamo, E; Papi, A; Riccini, A; Valdata, M

2008-01-01

31

Fast-response protection from high currents  

International Nuclear Information System (INIS)

Protection devices for power electronic equipment from shorting current are described. The device is shunted using spark gaps with minimal possible number of spark gaps to protect it. High fast-response (<100 ns) and operation voltage wide range (6-100 kV) are attained using Arkadiev-Marx generator-base trigger devices and air-core pulse transformer

32

Dynamic response of fast reactor primary containment  

International Nuclear Information System (INIS)

This paper describes the Czechoslovak approach to fast reactor primary containment problems. It is based on the assumption that the safety assessment of the containment requires an analysis of hypothetical accidents. The experimental programme consists of a sequence of tests using models of increasing complexity. The properties of model or reactor material are obtained with the help of Hopkinson-Davies bar apparatus. The theoretical effort is based on the mechanistic approach. In recent years, a series of codes has been developed in the Power Research Institute. This paper describes mainly the CEFRA code which can determine the dynamic response of fast reactor primary containment. Comparison of the CEFRA code with experimental results and some recent improvements in the code are discused. The code system was applied to a 600 MW fast reactor accident analysis and some results of the analysis are reported. (Auth.)

33

A fast-response shallow-water tide gauge  

International Nuclear Information System (INIS)

The authors describe the characteristics of a fast-response tide gauge suitable for shallow-water conditions. Its time constant is of the order of minutes. Wind waves are filtered better than 99% in the (0/10) s interval. The tide gauge has now been operative for three years on an oceanographic tower in the open sea. (author)

34

Time of flight fast neutron radiography  

Science.gov (United States)

Neutron radiography with fast or thermal neutrons is a standard technique for non-destructive testing (NDT). Here we report results for fast neutron radiography both as an adjunct to pulsed fast neutron analysis (PFNA) and as a stand-alone method for NDT. PFNA is a new technique for utilizing a collimated pulsed neutron beam to interrogate items and determine their elemental composition. By determining the time of flight for gamma-rays produced by (n,n' gamma X) reactions, a three dimensional image can be produced. Neutron radiography data taken with the same beam provides an important constraint for image reconstruction, and in particular is important in inferring the amount of hydrogen within the interrogated item. As a stand-alone device, the radiography measurement can be used to image items as large as cargo containers as long as their density is not too high. The use of a pulsed beam gives the further advantage of a time of flight measurement on the transmitted neutrons. By gating the radiography signal on the time of flight appropriate to the energy of the primary neutrons, most build-up from scattered neutrons can be eliminated. The pulsed beam also greatly improves the signal to background and extends the range of the neutron radiography. Simulation results will be presented which display the advantage of this constraint in particular for statistically limited data. Experimental results will be presented which show some of the limitations likely in a PFNA system utilizing neutron radiography data. Experimental and simulation results will demonstrate possible uses for this type of radiographic data in identifying contraband substances such as drugs.

Loveman, R.; Bendahan, J.; Gozani, T.; Stevenson, J.

1995-05-01

35

Fast exposure time decision in multi-exposure HDR imaging  

Science.gov (United States)

Currently available imaging and display system exists the problem of insufficient dynamic range, and the system cannot restore all the information for an high dynamic range (HDR) scene. The number of low dynamic range(LDR) image samples and fastness of exposure time decision impacts the real-time performance of the system dramatically. In order to realize a real-time HDR video acquisition system, this paper proposed a fast and robust method for exposure time selection in under and over exposure area which is based on system response function. The method utilized the monotony of the imaging system. According to this characteristic the exposure time is adjusted to an initial value to make the median value of the image equals to the middle value of the system output range; then adjust the exposure time to make the pixel value on two sides of histogram be the middle value of the system output range. Thus three low dynamic range images are acquired. Experiments show that the proposed method for adjusting the initial exposure time can converge in two iterations which is more fast and stable than average gray control method. As to the exposure time adjusting in under and over exposed area, the proposed method can use the dynamic range of the system more efficiently than fixed exposure time method.

Piao, Yongjie; Jin, Guang

2012-10-01

36

Long-time behaviour of fast breeders  

International Nuclear Information System (INIS)

For studying the long-time behaviour of fast breeders, a suitable O-dimensional model of fissile (plutonium), fertile (U238) and absorbing material (structural material and coolant) is investigated. Charging, discharging and re-charging of fissile and fertile material are idealized as continuous processes. Criticality requires continuous discharge of each specific Pu-composition . The time behaviour of the isotope composition is described by a first-order-differential- equation system whose solution was determined numerically for different initial conditions. Calculating the stationary isotope composition (stationary after a long time) leads to an eigenvalue problem with the plutonium current, to be discharged as eigenvalue and the Pu-isotope concentrations as eigenvector components. Generally, this eigenvalue problem has but one physically reasonable solution with the so-called Pu? as eigenvector. The eigenvalue determines the breeding rate. The principal structure of fuel recycling is investigated. (author)

37

Quartz Cherenkov counters for fast timing: QUARTIC  

Science.gov (United States)

We have developed particle detectors based on fused silica (quartz) Cherenkov radiators read out with microchannel plate photomultipliers (MCP-PMTs) or silicon photomultipliers (SiPMs) for high precision timing (?t ~ 10-15 ps). One application is to measure the times of small angle protons from exclusive reactions, p+p?p+X+p, at the Large Hadron Collider, LHC. They may also be used to measure directional particle fluxes close to external or stored beams. The detectors have small areas (cm2), but need to be active very close ( ~ 4 mm) to the intense LHC beam, and so must be radiation hard and nearly edgeless. We present results of tests of detectors with quartz bars inclined at the Cherenkov angle, and with bars in the form of an "L" (with a 90° corner). We also describe a possible design for a fast timing hodoscope with few mm2 elements.

Albrow, M. G.; Kim, Heejong; Los, S.; Mazzillo, M.; Ramberg, E.; Ronzhin, A.; Samoylenko, V.; Wenzel, H.; Zatserklyaniy, A.

2012-10-01

38

Estimating optimal time for fast chromatographic separations.  

Science.gov (United States)

(J. Sep. Sci. 2014, 37 (18), 2552-2558) DOI: 10.1002/jssc.201400508 The term tmin cc provides a ready estimate of the shortest time that can be obtained by "column cutting" for baseline resolution of two components showing excess chromatographic resolution. While actual column cutting is impractical, the tmin cc value is shown to be closely related to the minimum separation time obtainable by adjusting other parameters such as flow rate, mobile phase composition, and temperature, affording scientists interested in the development of fast chromatographic separations a convenient tool for estimating the minimum separation time that can be obtained by modifying a given method development screening result. Furthermore, the relationship between tmin cc and the minimum separation time obtainable by adjusting other parameters is shown to be dependent on the speed of the screening method, with aggressive screening gradients affording tmin cc estimates that match the actual minimum separation time, and "lazy" screening gradients affording tmin cc values that overestimate minimum separation time. Consequently, the analysis of the relationship between tmin cc and actual minimum separation time may be a useful tool for determining the "fitness" of method development screening methods. PMID:25201692

Welch, Christopher J; Regalado, Erik L

2014-09-01

39

Concomitant Effects of Ramadan Fasting and Time-Of-Day on Apolipoprotein AI, B, Lp-a and Homocysteine Responses during Aerobic Exercise in Tunisian Soccer Players  

Science.gov (United States)

Objective To examine the time-of-day and Ramadan fasting (RF) effects on serum apolipoprotein-AI (Apo-AI) and B (Apo-B), lipoprotein particles-a (Lp-a), high-sensitive C-reactive-protein (hs-CRP), and homocysteine (Hcy) during the Yo-Yo intermittent recovery test (YYIRT). Design Performance and biochemical measures were completed at two times-of-day (07:00 and 17:00 h), 1-week before RF (BR), the second week of RF (SWR), and the fourth week of RF (ER). Setting For each session, subjects performed the YYIRT, and blood samples were taken before and 3-min after the test for biochemical measures. Participants Fifteen soccer players. Main Outcome Measures Total distance during the YYIRT, core temperature, body composition, dietary intakes, lipid (HDL-C, LDL-C, Apo-AI, B and Lp-a) and inflammatory (hs-CRP and Hcy) profiles. Results Performances during the YYIRT were higher in the evening than the morning BR (P < 0.05), but this fluctuation was not observed during RF. Moreover, LDL-C, ApoB, and Lp-a were stable throughout the daytime BR. However, during RF, they decreased at 17:00 h (P < 0.05). Likewise, HDL-C and Apo-AI increased after the exercise and were higher at 17:00 h BR (P < 0.001). Moreover, these parameters increased during RF (P < 0.01). Furthermore, Hcy and hs-CRP increased during the exercise (P < 0.01) with higher evening levels BR. During ER, the diurnal pattern of Hcy was inversed (P < 0.001). Conclusions This study concluded that caloric restriction induced by RF seems to ameliorate lipid and inflammatory markers of cardiovascular health during intermittent exercise performed in the evening. PMID:24244572

Hammouda, Omar; Chtourou, Hamdi; Aloui, Asma; Chahed, Henda; Kallel, Choumous; Miled, Abdelhedi; Chamari, Karim; Chaouachi, Anis; Souissi, Nizar

2013-01-01

40

Fast-response beam loss monitor  

International Nuclear Information System (INIS)

By connecting a polyethylene fiber to a photo-multiplier, a beam loss monitor with a fast response has been fabricated. The beam loss is measured by Cherenkov light generated by a charged particle penetrating a fiber. Although this monitor has the merits that the structure of the monitor is simple and cheap, it has the demerits that the signal has an energy dependence, and deterioration caused by radiation occurs. A plastic scintillating fiber and a quartz fiber have also been tested. The signal of the former fiber is strong and does not depend on the energy of the circulating beam. However, the deterioration is also very severe. On the contrary, the latter fiber has a long lifetime, though its signal is small. Some measurements are discussed here concerning various cases of extraction conditions. (author)

 
 
 
 
41

A fast-response catalytic sensor for flammable gases  

Energy Technology Data Exchange (ETDEWEB)

A fast-response flammable-gas sensor has been developed, which has a typical response time of less than 1 s; this is approximately an order of magnitude less than that of a conventional diffusion-operated sensor. The reduction has been achieved by flowing the sampled gas directly over the sensing element and by operating the sensing element at a constant temperature, independent of reaction. The performance of the sensor has been evaluated in methane-air and butane-air mixtures using porous (poison-resistant) and non-porous ('pellistor'-type) sensing elements. 5 refs.

Dabill, D.W.; Gentry, S.J.; Walsh, P.T.

1987-03-01

42

Characteristics of fast response InSb submillimeter detector  

International Nuclear Information System (INIS)

A highly sensitive, fast responding n-InSb detector for the millimeter and submillimeter region has been fabricated and optimized for use to measure the electron cyclotron emission from tokamak plasmas, in connection with bandpass filters or a rapid scanning Fourier transform spectrometer. The detector element is made of high purity n-type InSb and is in magnetic fields up to 12 kG. The spectral responsivity, response time and noise equivalent power (NEP) of the detector have been measured. The response time of 0.2 ?sec, and NEP of 1.0 x 10-10 W/?H sub(z) at 4.2 K and 8 kG and that of 2.3 x 10-11 W/?H sub(z) at 1.8 K and 10 kG are obtained. These values are useful for the measurements of electron cyclotron emission from tokamak plasmas. (author)

43

A fast response temperature sensor based on fiber Bragg grating  

Science.gov (United States)

Aimed at the requirement for a fast-response expendable ocean temperature sensor, this paper presents a new design scheme for an optic fiber sensor. Ocean temperature sensors require high sensitivity and high response speed, which must be up to milliseconds. The fiber Bragg grating (FBG) temperature sensor with high sensitivity has been declared in the last decade, but its response speed has been rarely reported. In this paper, a method is proposed which is to package an FBG with a metal tube. The response time of this sensor is 48.6?ms, which is an order of magnitude greater than that of an ordinary optical fiber temperature sensor. Temperature sensitivity is 27.6?pm/°C and the linearity is up to 0.9999. In addition, the sensor can be less than 15?mm. It offers a new way to detect ocean temperature.

Zhang, Dengpan; Wang, Jin; Wang, Yongjie; Dai, Xing

2014-07-01

44

Fast infrared response of YBCO thin films  

International Nuclear Information System (INIS)

This paper reports on epitaxial thin films of superconducting YBCO by sputter deposition and by electron-beam evaporation. The sputter-deposited films were grown in-situ by rf magnetron sputtering from a single 8-inch diameter target onto substrates of MgO, LaAlO3, and LaGaO3 heated to 650--725 degrees C. By placing the substrate in the center of the magnetron racetrack and using a grounded shield to avoid negative ion bombardment, highly c-axis oriented films with Tc = 87 K were obtained. The evaporated films were prepared by coevaporation of Y, BaF2, and Cu onto SrTiO3 followed by post annealing in wet oxygen. The films have been used to investigate the interaction of YBCO with pulsed infrared laser radiation. Pulses 100 psec long from a Nd:YAG laser (? = 1.06 ?m) were directed onto a current biased line patterned into the superconducting film. It was found that the response was essentially bolometric in nature but with indirect evidence of nonequilibrium hot-electron transport. Fast switching (1 ns rise) of optically thick films could be obtained either by biasing the switch close to the critical current or by cooling the film below about 20 K. These results, which are similar to our earlier results with granular YBCO films, are encouraging for potential application to a high-current optically-triggered opening switch

45

A thermometer for fast response in cryogenic flow  

International Nuclear Information System (INIS)

The measurement of transient temperatures in cryogenic fluid flow requires a highly sensitive, intrinsically fast sensor that is in good thermal contact with the fluid but in poor thermal contact with the solid walls confining the fluid. A resistance thermometer made from a 1 ?m thick silicon layer on a 125 ?m thick sapphire substrate has a calculated intrinsic response time of about 10 ns at 4 K, and its sensitivity is comparable to germanium or carbon thermometers in the range of 1-80 K. This paper describes a novel construction method to mount the small silicon-on-sapphire thermometer in an oscillating fluid flow. The large surface area of the thermometer provides good thermal contact with the fluid, while the suspension ensures poor thermal contact with the holder, maintains its fast response time, and withstands high velocities and frequencies of fluid oscillation. A self-heating response time of 300 ns was measured at 4 K in liquid and gaseous helium. Repeatability of the thermometer is + or - 10 mK at 4 K. Examples of the performance of this thermometer for helium gas oscillations in the frequency range of 1 Hz to 12 kHz are given

46

Wave-induced hydroelastic response of fast monohull displacement ships  

DEFF Research Database (Denmark)

High-speed ships are weight sensitive structures and high strength steel, aluminium or composites are preferred building materials. It is characteristic for these materials that they result in larger hull flexibility than more conventional materials. Therefore, for large fast ships the lowest natural frequencies of the global hull modes can be relatively low compared to the frequency of wave encounter.In the present paper the effect of hull flexibility on the wave-induced springing and whipping vibrations is investigated in stationary stochastic seaways. The calculations are performed using a quadratic strip theory formulated in the frequency domain and a fully non-linear time-domain strip theory. The hydroelastic response is thereby excited partly by resonance and partly by non-linear excitation. The calculations are carried out for a recent proposal for a fast monohull containership.

Jensen, JØrgen Juncher; Wang, Zhaohui

1998-01-01

47

Actual preoperative fasting time in Brazilian hospitals: the BIGFAST multicenter study  

Science.gov (United States)

Background Prolonged fasting increases organic response to trauma. This multicenter study investigated the gap between the prescribed and the actual preoperative fasting times in Brazilian hospitals and factors associated with this gap. Methods Patients (18–90-years-old) who underwent elective operations between August 2011 and September 2012 were included in the study. The actual and prescribed times for fasting were collected and correlated with sex, age, surgical disease (malignancies or benign disease), operation type, American Society of Anesthesiologists score, type of hospital (public or private), and nutritional status. Results A total of 3,715 patients (58.1% females) with a median age of 49 (18–94) years from 16 Brazilian hospitals entered the study. The median (range) preoperative fasting time was 12 (2–216) hours, and fasting time was longer (P<0.001) in hospitals using a traditional fasting protocol (13 [6–216] hours) than in others that had adopted new guidelines (8 [2–48] hours). Almost 80% (n=2,962) of the patients were operated on after 8 or more hours of fasting and 46.2% (n=1,718) after more than 12 hours. Prolonged fasting was not associated with physical score, age, sex, type of surgery, or type of hospital. Patients operated on due to a benign disease had an extended duration of preoperative fasting. Conclusion Actual preoperative fasting time is significantly longer than prescribed fasting time in Brazilian hospitals. Most of these hospitals still adopt traditional rather than modern fasting guidelines. All patients are at risk of long periods of fasting, especially those in hospitals that follow traditional practices. PMID:24627636

de Aguilar-Nascimento, Jose E; de Almeida Dias, Ana L; Dock-Nascimento, Diana B; Correia, Maria Isabel TD; Campos, Antonio CL; Portari-Filho, Pedro Eder; Oliveira, Sergio S

2014-01-01

48

Polycrystalline CVD diamond detector: Fast response and high sensitivity with large area  

Energy Technology Data Exchange (ETDEWEB)

Polycrystalline diamond was successfully used to fabricate a large area (diameter up to 46 mm) radiation detector. It was proven that the developed detector shows a fast pulsed response time and a high sensitivity, therefore its rise time is lower than 5 ns, which is two times faster than that of a Si-PIN detector of the same size. And because of the large sensitive area, this detector shows good dominance in fast pulsed and low density radiation detection.

Liu, Linyue, E-mail: liulinyue@gmail.com; Zhang, Xianpeng; Zhong, Yunhong [Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Ouyang, Xiaoping, E-mail: oyxp@yahoo.com; Zhang, Jianfu [Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Xi' an Jiaotong University, Xi' an 710049 (China)

2014-01-15

49

Polycrystalline CVD diamond detector: Fast response and high sensitivity with large area  

Directory of Open Access Journals (Sweden)

Full Text Available Polycrystalline diamond was successfully used to fabricate a large area (diameter up to 46 mm radiation detector. It was proven that the developed detector shows a fast pulsed response time and a high sensitivity, therefore its rise time is lower than 5 ns, which is two times faster than that of a Si-PIN detector of the same size. And because of the large sensitive area, this detector shows good dominance in fast pulsed and low density radiation detection.

Linyue Liu

2014-01-01

50

Fast online corrections of tripping responses.  

Science.gov (United States)

Tripping over obstacles is one of the main causes of falls. One potential hazard to actually fall when tripped is inadequate foot landing. Adequate landing is required to control the body's angular momentum, while avoiding dangerous surfaces (slippery patch, uneven ground). To avoid such dangers, foot trajectory needs to be controlled by inhibiting and adjusting the initiated recovery foot path during a tripping reaction. We investigated whether such adjustments can be made without jeopardizing balance recovery. Sixteen healthy young adults (25.1 ± 3.2 years) walked at their comfortable speed over a walkway equipped with 14 hidden obstacles. Participants were tripped 10 times in between a random number of normal walking trials; five trips included a projection of a forbidden zone (FZ, 30 × 50 cm) at the subject's preferred landing position. Participants were instructed to land their recovery foot outside the FZ, if the FZ was presented. Responses were evaluated in terms of foot position and body angular momentum at and following recovery foot landing. Participants successfully landed their recovery foot outside the FZ in 80 % of trials, using strategies of either shortening their recovery steps (84 %) or side stepping (16 %). Their performance improved over trials, and some participants switched strategies. Angular momenta of the adjusted steps remained small at and following recovery foot landing. Young adults can quickly change foot trajectory after tripping by using different strategies, and without detrimental consequences on balance recovery, in terms of the angular momentum. These results open possibilities for training of tripping reactions. PMID:25070085

Potocanac, Zrinka; de Bruin, Janneke; van der Veen, Susanne; Verschueren, Sabine; van Dieën, Jaap; Duysens, Jacques; Pijnappels, Mirjam

2014-11-01

51

The Role of FAST in Pulsar Timing Arrays  

CERN Document Server

The Five-hundred-meter Aperture Spherical Telescope (FAST) will become one of the world-leading telescopes for pulsar timing array (PTA) research. The primary goals for PTAs are to detect (and subsequently study) ultra-low-frequency gravitational waves, to develop a pulsar-based time standard and to improve solar system planetary ephemerides. FAST will have the sensitivity to observe known pulsars with significantly improved signal-to-noise ratios and will discover a large number of currently unknown pulsars. We describe how FAST will contribute to PTA research and show that jitter- and timing-noise will be the limiting noise processes for FAST data sets. Jitter noise will limit the timing precision achievable over data spans of a few years while timing noise will limit the precision achievable over many years.

Hobbs, G; Manchester, R N; Shannon, R M; Kerr, M; Lee, K J; Xu, R

2014-01-01

52

Fast-timing methods for semiconductor detectors  

Energy Technology Data Exchange (ETDEWEB)

The basic parameters are discussed which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter.

Spieler, H.

1982-03-01

53

Fast-timing methods for semiconductor detectors  

International Nuclear Information System (INIS)

The basic parameters are discussed which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter

54

Fast timing methods for semiconductor detectors. Revision  

International Nuclear Information System (INIS)

This tutorial paper discusses the basic parameters which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter

55

Blunted metabolic response to fasting in obese mice.  

Science.gov (United States)

The aim of the study was to evaluate metabolic changes in response to fasting in normal and obese mice. C57BL6 and obese (diet-induced obesity (DIO) and ob/ob) mice were used in this study. They were fasted for 24 h and re-fed for 24 h. Body weight was monitored before, after fasting and during re-feeding (2 and 24 h after re-feeding). Food intake was measured 2 and 24 h after re-feeding began. Blood samples were taken before and after 24 h fasting. As metabolic parameters, blood glucose, plasma insulin, ghrelin levels and oxygen consumption were measured. Blood glucose and plasma insulin levels in DIO and ob/ob mice were higher than normal mice, and plasma ghrelin levels were lower in DIO and ob/ob mice. There was reduced body weight loss in DIO mice than in normal mice for 24 h fasting. When they were re-fed, DIO and ob/ob mice consumed less food intake than normal mice. Twenty-four hours food deprivation induced significantly smaller plasma ghrelin elevation in these obese mice. Fasting-induced decrease in oxygen consumption was significantly smaller in DIO and ob/ob mice than normal mice. This data show that obese mice may have decreased sensitivity to fasting-induced increase in circulating ghrelin and their oxygen consumption exhibited a blunted response to fasting. PMID:17975746

Ueno, Naohiko; Asakawa, Akihiro; Inui, Akio

2007-10-01

56

Time resolution studies of fast photomultipliers  

International Nuclear Information System (INIS)

The timing performances of two high speed RCA-C70045D photomultipliers were studied and compared with that of an optimised RCA-8850 photomultiplier. The C70045D is a 14 stage, side-on type tube employing a semi-transparent bi-alkali photocathode (cesium-potassium-antimony) of spherical section with beryllium oxide as the secondary emitting surface. This tube is not in the current RCA photomultipliers catalogue PIT-700C. In the earlier catalogue PIT-700B, it was listed as the fastest conventional photomultiplier. The test was carried out using a measuring system incorporating a subnanosecond light flasher. This had less than 200 ps rise time, with full width at half maximum of less than 300 ps and a repitition frequency capability of up to 1 MHz. The minimum overall time resolution of the measuring system was 132 ps. (orig.)

57

Quartz Cherenkov Counters for Fast Timing: QUARTIC  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have developed particle detectors based on fused silica (quartz) Cherenkov radiators read out with micro-channel plate photomultipliers (MCP-PMTs) or silicon photomultipliers (SiPMs) for high precision timing (Sigma(t) about 10-15 ps). One application is to measure the times of small angle protons from exclusive reactions, e.g. p + p - p + H + p, at the Large Hadron Collider, LHC. They may also be used to measure directional particle fluxes close to external or stored bea...

Albrow, M. G.; Kim, Heejong; Los, S.; Ramberg, E.; Ronzhin, A.; Samoylenko, V.; Wenzel, H.; Zatserklyaniy, A.

2012-01-01

58

Reaction Time 1: How Fast Are You ?  

Science.gov (United States)

In this lesson from Science NetLinks, students will engage in two online reaction time tests. They will track their progress, taking note of any strategies that help them improve their performance. This lesson takes a small step toward the broader learning goal described above; it encourages students to think about their learning and illustrates that skills, when practiced, can become automatic.

Science Netlinks;

2001-10-20

59

Actual preoperative fasting time in Brazilian hospitals: the BIGFAST multicenter study  

Directory of Open Access Journals (Sweden)

Full Text Available José E de Aguilar-Nascimento,1 Ana L de Almeida Dias,2 Diana B Dock-Nascimento,3 Maria Isabel TD Correia,4 Antonio CL Campos,5 Pedro Eder Portari-Filho,6 Sergio S Oliveira71Department of Surgery, Julio Muller University Hospital, Cuiaba, Brazil; 2Federal University of Mato Grosso, Cuiaba, Brazil; 3Department of Sciences and Food, Federal University of Mato Grosso, Cuiaba, Brazil; 4Department of Surgery, Federal University of Minas Gerais, Belo Horizonte, Brazil; 5Department of Surgery, Federal University of Parana, Curitiba, Brazil; 6Department of Surgery, Federal University of Rio de Janeiro State, Rio de Janeiro, Brazil; 7Service of Anesthesiology, Julio Muller University Hospital, Cuiaba, Brazil On behalf of the BIGFAST (Brazilian Group for the Study of Preoperative Fasting Time group Background: Prolonged fasting increases organic response to trauma. This multicenter study investigated the gap between the prescribed and the actual preoperative fasting times in Brazilian hospitals and factors associated with this gap. Methods: Patients (18–90-years-old who underwent elective operations between August 2011 and September 2012 were included in the study. The actual and prescribed times for fasting were collected and correlated with sex, age, surgical disease (malignancies or benign disease, operation type, American Society of Anesthesiologists score, type of hospital (public or private, and nutritional status. Results: A total of 3,715 patients (58.1% females with a median age of 49 (18–94 years from 16 Brazilian hospitals entered the study. The median (range preoperative fasting time was 12 (2–216 hours, and fasting time was longer (P<0.001 in hospitals using a traditional fasting protocol (13 [6–216] hours than in others that had adopted new guidelines (8 [2–48] hours. Almost 80% (n=2,962 of the patients were operated on after 8 or more hours of fasting and 46.2% (n=1,718 after more than 12 hours. Prolonged fasting was not associated with physical score, age, sex, type of surgery, or type of hospital. Patients operated on due to a benign disease had an extended duration of preoperative fasting. Conclusion: Actual preoperative fasting time is significantly longer than prescribed fasting time in Brazilian hospitals. Most of these hospitals still adopt traditional rather than modern fasting guidelines. All patients are at risk of long periods of fasting, especially those in hospitals that follow traditional practices. Keywords: preoperative fasting, preoperative care, multicenter study, intraoperative complications, guideline adherence, perioperative risk

Aguilar-Nascimento JE

2014-02-01

60

Plastic fiber scintillator response to fast neutronsa)  

Science.gov (United States)

The Neutron Imaging System at NIF uses an array of plastic scintillator fibers in conjunction with a time-gated imaging system to form an image of the neutron emission from the imploded capsule. By gating on neutrons that have scattered from the 14.1 MeV DT energy to lower energy ranges, an image of the dense, cold fuel around the hotspot is also obtained. An unmoderated spallation neutron beamline at the Weapons Neutron Research facility at Los Alamos was used in conjunction with a time-gated imaging system to measure the yield of a scintillating fiber array over several energy bands ranging from 1 to 15 MeV. The results and comparison to simulation are presented.

Danly, C. R.; Sjue, S.; Wilde, C. H.; Merrill, F. E.; Haight, R. C.

2014-11-01

 
 
 
 
61

Fast-response liquid crystal variable optical retarder and multilevel attenuator  

Science.gov (United States)

We propose and demonstrate a fast-response liquid crystal (LC) variable optical retarder or attenuator with several transmission levels. The fast-response LC optical device consists of dual ?-cells. The device is designed so that the transition between any two states is controlled by the application of an increased voltage level rather than by applying a lower level. This design offers transition times in the range of tens of microseconds between any transmission states. A limitation of the device is that the time between transitions cannot be arbitrarily short and is typically milliseconds.

Cheng, HsienHui; Bhowmik, Achintya; Bos, Philip J.

2013-10-01

62

Time-resolved fast neutron imaging: simulation of detector performance  

CERN Document Server

We have analyzed and compared the performance of two novel fast-neutron imaging methods with time-of-flight spectroscopy capability. Using MCNP and GEANT code simulations of neutron and charged-particle transport in the detectors, key parameters such as detection efficiency, the amount of energy deposited in the converter and the spatial resolution of both detector variants have been evaluated.

Vartsky, D; Goldberg, M B; Mardor, I; Feldman, G; Bar, D; Shor, A; Dangendorf, V; Laczko, G; Breskin, Amos; Chechik, R

2004-01-01

63

Fast neutron response of quartz fibre pocket dosimeters  

International Nuclear Information System (INIS)

During the handling of californium-252 sources, high burn-up plutonium and photoneutron sources, a quick assessment of gamma radiation exposure is carried out by using quartz fibre pocket dosimeters. For an estimation of neutro n dose, fast neutron dosimeters are frequently used. In this paper, fast neutron response of quartz fibre dosimeters of Stephen, Victoreen and BARC makes were studied by exposing them to standard 252Cf source (about 655 ?g ) and 239Pu-Be source (74 GBq) and results were compared with fast neutron dosimeters of Dosimeter Corporation of America. Except for the lower response of BARC make dosimeters for 252Cf neutrons, the response for all dosimeters to fast neutron is similar (within ± 30 per cent). The reading of the dosimeters approximately corresponds to neutron dose in Rad. The data was explained on the basis of events produced in construction material of the dosimeters. These quartz fibre pocket dosimeters can be therefore used for neutron monitoring when gamma field is low. (author). 2 tabs., 1 fig

64

A new dual threshold time-over-threshold circuit for fast timing in PET  

Science.gov (United States)

Time-over-threshold (ToT) is attractive as a method of combined timing and energy encoding in positron emission tomography (PET) due to its simplicity in implementation and readout. However, conventional single threshold ToT has a nonlinear response and generally suffers from a tradeoff between timing and energy resolution. The resulting poor performance is not fit for applications requiring fast timing, such as time-of-flight (ToF) PET. In this work it is shown experimentally that by replacing single threshold ToT with a dual threshold method in a new compact circuit, excellent time resolution can be achieved (154 ps FWHM for 3 × 3 × 5 mm3 LYSO crystals), suitable for ToF. Dual threshold ToT timing results have been compared to a similar single threshold design, demonstrating that dual threshold ToT performance is far superior to that of single threshold ToT (154 ps versus 418 ps coincidence time resolution for the dual and single threshold cases, respectively). A method of correcting for nonlinearity in dual threshold ToT energy spectra is also demonstrated.

Grant, Alexander M.; Levin, Craig S.

2014-07-01

65

Fast time-resolved aerosol collector: proof of concept  

Directory of Open Access Journals (Sweden)

Full Text Available Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol collector ("Fast-TRAC" microscopically observes the particle collection on a substrate and records an on-line video. Particle arrivals are resolved to within a single frame (4–17 ms in this setup, and the spatial locations are matched to the subsequent single particle analysis. This approach also provides in-situ information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and surface long-term monitoring.

X.-Y. Yu

2010-06-01

66

Fast time-resolved aerosol collector: proof of concept  

Directory of Open Access Journals (Sweden)

Full Text Available Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol collector ("Fast-TRAC" microscopically observes the particle collection on a substrate and records an on-line video. Particle arrivals are resolved to within a single frame (4–17 ms in this setup, and the spatial locations are matched to the subsequent single particle analysis. This approach also provides in-situ information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and surface long-term monitoring.

X.-Y. Yu

2010-10-01

67

Verification of the CNGS timing system using fast diamond detectors  

Science.gov (United States)

A new fast diagnostic tool was installed in the CNGS facility in 2011 following the neutrino time-of-flight results published by OPERA in September 2011. Among others, four polycrystalline CVD (pCVD) diamond detectors were placed in the secondary beam line about 1200 m downstream of the CNGS target in order to measure the beam structure of the muons which are produced together with the muon neutrinos. Upstream of the CNGS target, a fast beam current transformer measures the proton beam structure. The sub-nanosecond single-pulse time resolution of pCVD diamond for a minimum ionising particle in combination with a GPS system allows the measurement of the GPS timing of individual secondary particle bunches crossing these detectors with a precision of GPS timing measurements performed at CERN are consistent.

Jansen, H.; Alvarez Sanchez, P.; Pedersen, S. Bart; Dehning, B.; Dobos, D.; Effinger, E.; Ferrari, A.; Griesmayer, E.; Gschwendtner, E.; Kozsar, I.; Missiaen, D.; Pernegger, H.; Sala, P. R.; Serrano, J.; Ward, C.

2013-01-01

68

Real time simulation method for fast breeder reactors dynamics  

International Nuclear Information System (INIS)

The development of multi-purpose real time simulator models with suitable plant dynamics was made; these models can be used not only in training operators but also in designing control systems, operation sequences and many other items which must be studied for the development of new type reactors. The prototype fast breeder reactor ''Monju'' is taken as an example. Analysis is made on various factors affecting the accuracy and computer load of its dynamic simulation. A method is presented which determines the optimum number of nodes in distributed systems and time steps. The oscillations due to the numerical instability are observed in the dynamic simulation of evaporators with a small number of nodes, and a method to cancel these oscillations is proposed. It has been verified through the development of plant dynamics simulation codes that these methods can provide efficient real time dynamics models of fast breeder reactors. (author)

69

NASA AVOSS Fast-Time Wake Prediction Models: User's Guide  

Science.gov (United States)

The National Aeronautics and Space Administration (NASA) is developing and testing fast-time wake transport and decay models to safely enhance the capacity of the National Airspace System (NAS). The fast-time wake models are empirical algorithms used for real-time predictions of wake transport and decay based on aircraft parameters and ambient weather conditions. The aircraft dependent parameters include the initial vortex descent velocity and the vortex pair separation distance. The atmospheric initial conditions include vertical profiles of temperature or potential temperature, eddy dissipation rate, and crosswind. The current distribution includes the latest versions of the APA (3.4) and the TDP (2.1) models. This User's Guide provides detailed information on the model inputs, file formats, and the model output. An example of a model run and a brief description of the Memphis 1995 Wake Vortex Dataset is also provided.

Ahmad, Nash'at N.; VanValkenburg, Randal L.; Pruis, Matthew

2014-01-01

70

Fast response of InSb Schottky detector.  

Science.gov (United States)

An InSb Schottky detector, fabricated from an undoped InSb wafer with Hall mobility which is higher than those of previously employed InSb wafers, was used for alpha particle detection. The output pulse of this InSb detector showed a very fast rise time, which was comparable with the output pulses of scintillation detectors. PMID:17552865

Kanno, Ikuo; Hishiki, Shigeomi; Kogetsu, Yoshitaka; Nakamura, Tatsuya; Katagiri, Masaki

2007-05-01

71

Fast response of InSb Schottky detector  

International Nuclear Information System (INIS)

An InSb Schottky detector, fabricated from an undoped InSb wafer with Hall mobility which is higher than those of previously employed InSb wafers, was used for alpha particle detection. The output pulse of this InSb detector showed a very fast rise time, which was comparable with the output pulses of scintillation detectors

72

Study of the response time of MR dampers  

Science.gov (United States)

Response time is an important parameter which determines the applied fields and practical vibration reduction effects of magnetorheological (MR) dampers. However, up to now, only a few papers discuss the test and analysis of response times. In this paper, the response time of a large-scale MR damper at different velocities and currents was firstly tested. Then, the transient magnetic field excited by the time-variant excitation current was simulated by finite element method (FEM). Based on the variation of the shear yield stress of magnetorheological fluids in the gap between the cylinder and the piston, the response time of the MR damper was investigated. Influences of eddy current and excitation current response time on the damper's response were also explored. Results show that by utilizing finite elements method, the calculated average effective shear yield strength can be used to predict the response time of a MR damper. Electromagnetic response is the predominant factor influencing the response time of a MR damper, and reducing eddy currents is the key to accelerate the response of a MR damper. Moreover, influence of eddy currents is much larger under stepping down excitation currents than stepping up currents, and with a same magnitude of step, no matter when the current increases or decreases, the smaller the initial current, the greater the eddy current affects a damper's response and the longer the response time of damping force is. A fast response excitation current may induce large eddy currents which reduce the response of the damper instead.

Guan, Xinchun; Guo, Pengfei; Ou, Jinping

2009-07-01

73

The Impact of Maternal Smoking on Fast Auditory Brainstem Responses  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Deficits in auditory processing have been posited as one of the underlying neurodevelopmental consequences of maternal smoking during pregnancy that leads to later language and reading deficits. Fast auditory brainstem responses were used to assess differences in the sensory processing of auditory stimuli among infants with varying degrees of prenatal cigarette exposure. Maternal report of consumption of cigarettes and blood samples were collected in the hospital to assess exposure levels and...

Kable, Julie A.; Coles, Claire D.; Lynch, Mary Ellen; Carroll, Julie

2009-01-01

74

A fast tube of response ray-tracer  

International Nuclear Information System (INIS)

A ray-tracing algorithm is proposed to quickly approximate volumes of intersection between an arbitrary tube of response and a voxel array. The method is based on the idea of the Wu antialiased line tracer that is well known in the computer graphics community. However, our method works in three dimensions and supports arbitrary symmetrical response profile functions. The inner loop implementation does not use any conditional branching and is aware of low-level optimization strategies. The running speed of a fast incremental Siddon routine appears to be about 60% slower than our algorithm

75

Fast and thermal neutron response of BeO and Li2B4O7  

International Nuclear Information System (INIS)

The thermal and fast neutron response of BeO (four types) and Li2B4O7:Mn, in comparison with that of LiF (TLD-100 and TLD-700) and CaF2:Mn, has been investigated. For fast neutrons, the response of all the investigated phosphors was found to be negligible compared with their ?-response. For thermal neutrons, the four types of BeO as well as CaF2:Mn showed a very poor response, below that of TLD-700, while Li2B4O7:Mn gave a response similar to that of TLD-100 and was nearly 1500 times that of BeO. (orig.)

76

Fast-response processor for data selection and processing in a multichannel analog-to-digital converter  

International Nuclear Information System (INIS)

A multichannel analog-to-digital converter representing the base of the fast channel of the system for multiplex measurement of amplitudes and timing parameters is described. The fast-response processor switched into the measuring channel is intended for data selection by predetermined criteria and on-line processing and compression of the recorded data

77

Fast computation of recurrences in long time series  

Science.gov (United States)

The quadratic time complexity of calculating basic RQA measures, doubling the size of the input time series leads to a quadrupling in operations, impairs the fast computation of RQA in many application scenarios. As an example, we analyze the Potsdamer Reihe, an ongoing non-interrupted hourly temperature profile since 1893, consisting of 1,043,112 data points. Using an optimized single-threaded CPU implementation this analysis requires about six hours. Our approach conducts RQA for the Potsdamer Reihe in five minutes. We automatically split a long time series into smaller chunks (Divide) and distribute the computation of RQA measures across multiple GPU devices. To guarantee valid RQA results, we employ carryover buffers that allow sharing information between pairs of chunks (Recombine). We demonstrate the capabilities of our Divide and Recombine approach to process long time series by comparing the runtime of our implementation to existing RQA tools. We support a variety of platforms by employing the computing framework OpenCL. Our current implementation supports the computation of standard RQA measures (recurrence rate, determinism, laminarity, ratio, average diagonal line length, trapping time, longest diagonal line, longest vertical line, divergence, entropy, trend) and also calculates recurrence times. To utilize the potential of our approach for a number of applications, we plan to release our implementation under an Open Source software license. It will be available at http://www.gfz-potsdam.de/fast-rqa/. Since our approach allows to compute RQA measures for a long time series fast, we plan to extend our implementation to support multi-scale RQA.

Rawald, Tobias; Sips, Mike; Marwan, Norbert; Dransch, Doris

2014-05-01

78

Modeling and Analysis of the Role of Fast-Response Energy Storage in the Smart Grid  

CERN Document Server

The large short time-scale variability of renewable energy resources presents significant challenges to the reliable operation of power systems. This variability can be mitigated by deploying fast-ramping generators. However, these generators are costly to operate and produce environmentally harmful emissions. Fast-response energy storage devices, such as batteries and flywheels, provide an environmentally friendly alternative, but are expensive and have limited capacity. To study the environmental benefits of storage, we introduce a slotted-time dynamic residual dc power flow model with the prediction error of the difference between the generation (including renewables) and the load as input and the fast-ramping generation and the storage (charging/discharging) operation as the control variables used to ensure that the demand is satisfied (as much as possible) in each time slot. We assume the input prediction error sequence to be i.i.d. zero-mean random variables. The optimal power flow problem is then formu...

Su, Han-I

2011-01-01

79

Equipment for fast neutron time-of-flight experiments  

International Nuclear Information System (INIS)

A 3-MeV-pulsed Van de Graaff has been built for this laboratory by the High Voltage Engineering Corporation of Boston, United States of America. It is designed to give pulses of 1 ns duration at a repetition frequency of 1 MHz and a current in the pulse of 10 mA. This machine is to be used for fast neutron spectroscopy and a system of electronics for this purpose has been devised. The system is intended to record time intervals up to 1?s with a resolution of ?3 ns. The timing cycle is started by a start pulse from the neutron detector. The stop pulse is derived from the beam, and delayed by 1?s. The start and stop pulses are fed to a time expander which expands the time interval between the pulses by a factor of ?250. The expanded time interval is then recorded in digital form on 16-track magnetic tape. (author)

80

Fast fall-time ion beam in neutron generators  

International Nuclear Information System (INIS)

Ion beam with a fast fall time is useful in building neutron generators for the application of detecting hidden, gamma-shielded SNM using differential die-away (DDA) technique. Typically a fall time of less than 1 (micro)s can't be achieved by just turning off the power to the ion source due to the slow decay of plasma density (partly determined by the fall time of the RF power in the circuit). In this paper, we discuss the method of using an array of mini-apertures (instead of one large aperture beam) such that gating the beamlets can be done with low voltage and a small gap. This geometry minimizes the problem of voltage breakdown as well as reducing the time of flight to produce fast gating. We have designed and fabricated an array of 16 apertures (4 x 4) for a beam extraction experiment. Using a gating voltage of 1400 V and a gap distance of 1 mm, the fall time of extracted ion beam pulses is less than 1 (micro)s at various beam energies ranging between 400 eV to 800 eV. Usually merging an array of beamlets suffers the loss of beam brightness, i.e., emittance growth, but that is not an important issue for neutron source applications

 
 
 
 
81

Fast Fall-time Ion Beam in Neutron Generators  

International Nuclear Information System (INIS)

Ion beam with a fast fall time is useful in building neutron generators for the application of detecting hidden, gamma-shielded SNM using differential die-away (DDA) technique. Typically a fall time of less than 1 ?s can't be achieved by just turning off the power to the ion source due to the slow decay of plasma density (partly determined by the fall time of the RF power in the circuit). In this paper, we discuss the method of using an array of mini-apertures (instead of one large aperture beam) such that gating the beamlets can be done with low voltage and a small gap. This geometry minimizes the problem of voltage breakdown as well as reducing the time of flight to produce fast gating. We have designed and fabricated an array of 16 apertures (4x4) for a beam extraction experiment. Using a gating voltage of 1400 V and a gap distance of 1 mm, the fall time of extracted ion beam pulses is less than 1 ?s at various beam energies ranging between 400 eV to 800 eV. Usually merging an array of beamlets suffers the loss of beam brightness, i.e., emittance growth, but that is not an important issue for neutron source applications.

82

Fast Responsive Gas Sensor of Vertically Aligned Fluorine-Doped Tin Oxide Nanorod Thin Film  

Science.gov (United States)

We prepared fluorine-doped tin oxide (FTO) nanorod films and a conventional FTO thin film for the application of a semiconducting gas sensor by spray pyrolysis method. The lengths of FTO nanorods (FTON, 100 and 500 nm) were controlled by changing deposition times, and FTO thin film (FTOT) was also prepared as a reference. The gas sensitivity test shows FTON with long nanorods had higher sensitivity for both hydrogen and ethanol gases but slow response and recovery times, despite an advantage of the higher gas sensitivity. FTO nanorod film with short length about 100 nm showed relatively lower sensitivity, but fast gas response and recovery characteristics. The fast response and recovery for the analyte gases are attributed to the conductance of FTO nanorods, which is closely related to the diameter and length of nanorods.

Cho, Chan-Woo; Lee, Jong-Heun; Riu, Doh-Hyung; Kim, Chang-Yeoul

2012-04-01

83

Wave-induced Hydroelastic response of fast monohull ships  

DEFF Research Database (Denmark)

High-speed ships are weight sensitive structures and high strength steel, aluminium or composites are preferred building materials. it is characteristic for these materials that they result in larger hull flexibility than more conventional materials. Therefore, for large fast ships the lowest natural frequencies of the global hull modes can be relatively low compared to the frequency of wave encounter. In the present paper the effect of hull flexibility on the wave-induced springing vibrations is investigated in stationary stochastic seaways. The calculations are performed within the framework of a quadratic strip theory formulated in the frequency domain. The springing response is thereby excited partly be resonance and partly by non-linear excitation. Special emphasis is given to the influence of springing on fatigue damage as the extreme responses even for very flexible ships are quite insensitive to the hull flexibility due to the high zero crossing periods associated with the extreme responses.

Jensen, JØrgen Juncher

1996-01-01

84

Fast and Slow Transient Response of WECS with Simultaneous Actions  

Directory of Open Access Journals (Sweden)

Full Text Available This paper details the transient operation of a wind energy conversion system (WECS used simultaneously as an ac- tive filter and power generator. This study is intended to address the system response to two types of transient phenomena: voltage dips (fast transients and wind speed variations (slow transients. The system response to voltage dips is governed by the electrical system dynamics and control method and results in the evaluation of the WECS low-voltage ride through capability. The study of the system response to wind speed variations requires a complete me- chanical model to be included. Simulation results are presented for a typical WECS, and a discussion is carried out dealing with the generalization of the present work to other configurations.

M.Amarendra

2012-03-01

85

Another approach to fast neutron response of some thermoluminescent materials  

International Nuclear Information System (INIS)

Experimental data concerning fast neutron response of some thermoluminescent materials were analyzed with the aim of finding an analytical expression for their dependence on neutron energy. Both relative responses and relative thremoluminescent yields were studied, the analysis was performed for sup(nat)LiF, 7LiF, Al2O3, and CaSO4. Fitting was carried out using a non-linear least squares curve fitting program. Analytical functions for both quantities were found, their correspondence to the experimental data is discussed for energies between 0.25 and 20 MeV. The usefulness of the fitted functinons is analyzed, the expressions were used to predict relative responses for some polyenergetic sources, agreement with experimental data is discussed. The predicted dependences of thermoluminescent yields on neutron energy are also analyzed. (author)

86

Verification of the CNGS timing system using fast diamond detectors  

International Nuclear Information System (INIS)

A new fast diagnostic tool was installed in the CNGS facility in 2011 following the neutrino time-of-flight results published by OPERA in September 2011. Among others, four polycrystalline CVD (pCVD) diamond detectors were placed in the secondary beam line about 1200 m downstream of the CNGS target in order to measure the beam structure of the muons which are produced together with the muon neutrinos. Upstream of the CNGS target, a fast beam current transformer measures the proton beam structure. The sub-nanosecond single-pulse time resolution of pCVD diamond for a minimum ionising particle in combination with a GPS system allows the measurement of the GPS timing of individual secondary particle bunches crossing these detectors with a precision of < 1 ns. The complicated structure of the CNGS muon beam in 2011 necessitates the combination of adjacent bunches in order to compare the proton beam structure with the muon beam structure. An analysis of the detector signals was carried out, which provides an independent timing measurement at CERN with a precision of 1.2 ns. Uncertainties from other sources as cable lengths add up to 3.4 ns, resulting in an overall precision of 3.6 ns. The distance between the beam current transformer and the diamond detectors has been measured to (1859.95±0.02) cm. The nominal time-of-flight of (6205.3±1.7) ns for a 17 GeV/c muon, as present in the CNGS muons beam, falls within the uncertainties of the measured time-of-flight of (6205.2±the measured time-of-flight of (6205.2±3.6) ns. Hence, the GPS timing measurements performed at CERN are consistent.

87

Fast minute magnetic field coil for time-resolved nanospintronics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nanospintronic and related research often requires the application of fast rising magnetic field pulses in the plane of the studied planar structure. We have designed and fabricated sub-milimeter-sized coils capable of delivering pulses of the magnetic field up to ~ 500 Oe in the plane of the sample with the rise time of order of 10 ns. The placement of the sample above the coil allows for an easy access to its surface with manipulators or light beams for, e.g., Kerr microsc...

Pawliszak, ?ukasz; Tekielak, Maria; Zgirski, Maciej

2014-01-01

88

A fast rise time high voltage pulse burst generator  

International Nuclear Information System (INIS)

A novel type of pulse generator for kicker magnet excitation is described. Series connected thyratrons and coaxial lines are used to produce a burst of four 20 kv, 800 a, fixed length pulses of fast rise and fall time. Inter-pulse spacing is independently adjustable, typically between 200 ns and 20 ?s. The coaxial lines are simultaneously resonantly charged to 40 kv in 1 ms, and the subsequent triggered discharge of each pulse forming network (PFN) initiates the pulse bursts which may be produced at a repetition frequency of 100 hz. This paper presents some of the results obtained with a prototype pulse generator

89

Repetitive trigger generator with low jitter and fast rise time  

International Nuclear Information System (INIS)

A repetitive trigger generator with low jitter and fast rise time is introduced and the principle of designing and choosing the units in the trigger generator are given. The trigger generator is composed with control unit, charging unit and pulse forming unit. The pulse forming unit is a capacitor-fast-discharging trigger with hydrogen thyratron. The repetitive rate of trigger can reach 100 pps (pulses per second), the delay time is about 225 ns, the jitter is about 1 ns, the rise time is about 26 ns and the FWHM (full-width at half-magnitude) is about 70 ns. The amplitude of electrical pulse on the load with high impedance is about -40 kV at 100 pps, -51 kV at 50 pps, -60 kV at singe shot, respectively. The micro-closing of hydrogen thyratron is discussed. As the anode voltage increases, the duration of micro-closing increases and the resistance of switch decreases. The effect of heating voltage on the breakdown characteristic of hydrogen thyratron is discussed as well. (authors)

90

Fast-response liquid-crystal lens for 3D displays  

Science.gov (United States)

Three-dimensional (3D) display has become an increasingly important technology trend for information display applications. Dozens of different 3D display solutions have been proposed. The autostereoscopic 3D display based on lenticular microlens array is a promising approach, and fast-switching microlens array enables this system to display both 3D and conventional 2D images. Here we report two different fast-response microlens array designs. The first one is a blue phase liquid crystal lens driven by the Pedot: PSS resistive film electrodes. This BPLC lens exhibits several attractive features, such as polarization insensitivity, fast response time, simple driving scheme, and relatively low driving voltage, as compared to other BPLC lens designs. The second lens design has a double-layered structure. The first layer is a polarization dependent polymer microlens array, and the second layer is a thin twisted-nematic (TN) liquid crystal cell. When the TN cell is switched on/off, the traversing light through the polymeric lens array is either focused or defocused, so that 2D/3D images are displayed correspondingly. This lens design has low driving voltage, fast response time, and simple driving scheme. Simulation and experiment demonstrate that the performance of both switchable lenses meet the requirement of 3D display system design.

Liu, Yifan; Ren, Hongwen; Xu, Su; Li, Yan; Wu, Shin-Tson

2014-02-01

91

Pediatric fasting times before surgical and radiologic procedures: benchmarking institutional practices against national standards.  

Science.gov (United States)

Prolonged preoperative fasting can be associated with adverse outcomes, particularly in children. Our aims were to assess the time pediatric patients fasted prior to surgical or radiologic procedures and evaluate whether fasting (NPO) orders complied with national guidelines. We measured NPO start time, time of last intake, and time test or surgery was scheduled, took place, or was cancelled in 219 pediatric patients. Findings demonstrate that pediatric patients experienced prolonged fasting before procedures and that the majority of NPO orders were non-compliant with national guidelines. We have developed strategies to reduce fasting times and ensure compliance with recommended national fasting standards. PMID:24365219

Williams, Catherine; Johnson, Pat A; Guzzetta, Cathie E; Guzzetta, Philip C; Cohen, Ira Todd; Sill, Anne M; Vezina, Gilbert; Cain, Sherry; Harris, Christine; Murray, Jodi

2014-01-01

92

Fast responsive, optical trace level ammonia sensor for environmental monitoring  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Ammonia is a ubiquitous chemical substance which is created in technical and biological processes and harmful to many different organisms. One specific problem is the toxicity of ammonia in fish at levels of 25 ?g/l - a very common issue in today’s aqua culture. In this study we report a development of a fast responsive, optical ammonia sensor for trace concentrations. Results Different hydrogels have been investigated as host polymers for a pH based sensing mechanism based on fluorescent dyes. A porous hydrophobic fluoropolymer membrane was used as an ion barrier cover layer to achieve a good ammonia permeability. The sensor’s sensitivity towards ammonia as well as crosssensitivity towards pH-value and salinity, and the temperature dependency have been determined. Two different methods to reference fluorescence signals have been employed to eliminate intensity-based measurement drawbacks. Conclusion The presented sensor features high sensitivity and a fast response even at concentrations near 1 ppb. No cross sensitivity towards pH and salinity could be observed and temperature dependency was determined as compensateable. Both referencing approaches prove themselves to be able to provide a simple use of the sensor for in-field applications.

Abel Tobias

2012-10-01

93

Analog-assisted digital low dropout regulator with fast transient response and low output ripple  

Science.gov (United States)

An analog-assisted digital low dropout regulator (AAD-LDO) is proposed to solve the problems of a slow transient response and a large output ripple in a conventional digital LDO. In the AAD-LDO, a fast-response auxiliary analog LDO is added to the digital LDO in parallel. Compared with the digital LDO, the measured AAD-LDO in 180 nm CMOS reduces the transient response time and the output ripple by 59 and 28%, respectively, at the same current efficiency of 97.1%. The line regulation is 15 mV/V and the load regulation is 0.63 mV/mA.

Mori, Kazuaki; Okuma, Yasuyuki; Zhang, Xin; Fuketa, Hiroshi; Sakurai, Takayasu; Takamiya, Makoto

2014-01-01

94

TimTrack: A matrix formalism for a fast time and track reconstruction with timing detectors  

International Nuclear Information System (INIS)

An easy and fast matrix formalism for the tracking of charged particles through timing detectors is presented. The method is based on the least squares method and works directly with the first level data, that is, positions and readout times provided by timing detectors. In one step it provides the coordinates, the slopes, the velocity and an offset time at a given reference plane. The formalism is applied to some examples.

95

Fabrication and Characteristics of Fast Photo Response ZnO/Porous Silicon UV Photoconductive Detector  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Fast response time UV photoconductive detector was fabricated based on ZnO film prepared by thermal chemical spray pyrolysis technique. The ZnO nanofilms are grown on the porous silicon (PS) nanosurface which has drastically reduced the response time of the ZnO UV detector from few seconds to few hundreds of microseconds. The surface functionalization of the ZnO film deposited on porous silicon (PS) layer by polyamide nylon has highly improved the photoresponsivity of the detector to 0.8 A/W....

Thjeel, Hanan A.; Suhail, Abdulla M.; Naji, Asama N.; Al-zaidi, Qahtan G.; Muhammed, Ghaida S.; Naum, Faten A.

2011-01-01

96

Diamond detectors for ultra-fast fission-fragment timing  

International Nuclear Information System (INIS)

The precise knowledge about delayed neutron (DN) yields in fission is highly relevant for the reliable control of nuclear reactors and the save operation of sub-critical assemblies, like e. g. ADS, where minor actinides are mixed into the nuclear fuel. One way to achieve a more fundamental understanding of the production of so-called DN pre-cursor isotopes in fission is to measure the emission yields with high mass resolution. For this purpose a two-arm time-of-flight spectrometer for high resolution fission-fragment spectrometry is being built at the Institute for Reference Materials and Measurements, a Joint Research Centre of the European Commission. The ultimate goal is to achieve a mass resolution A/?A?120 in conjunction with a reasonable counting efficiency. One pre-requisite for such a device is the use of ultra-fast timing detectors. For this purpose poly-crystalline chemical vapour deposited (pcCVD) diamond detectors have been tested for the first time as time pick-up for binary fission fragments. In particular, the charge-collection efficiency has been investigated as a function of the irradiation time, which corresponds to the integral dose applied to the detector material. The intrinsic timing resolution for fission fragments has been determined to be better than 40 ps

97

A fast preamplifier concept for SiPM-based time-of-flight PET detectors  

International Nuclear Information System (INIS)

Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically >300 pF for a 3 mm×3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpedance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a ‘slow’ energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3 mm×3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm×3 mm×5 mm LaBr3:Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

98

A fast preamplifier concept for SiPM-based time-of-flight PET detectors  

Energy Technology Data Exchange (ETDEWEB)

Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically >300 pF for a 3 mm Multiplication-Sign 3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpedance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a 'slow' energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3 mm Multiplication-Sign 3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm Multiplication-Sign 3 mm Multiplication-Sign 5 mm LaBr{sub 3}:Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

Huizenga, J., E-mail: j.huizenga@tudelft.nl [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Seifert, S. [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Schreuder, F. [Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); Dam, H.T. van [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands); Dendooven, P.; Loehner, H.; Vinke, R. [Kernfysisch Versneller Instituut, University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); Schaart, D.R. [Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft (Netherlands)

2012-12-11

99

Metabolomics of Ramadan fasting: an opportunity for the controlled study of physiological responses to food intake  

Science.gov (United States)

High-throughput screening techniques that analyze the metabolic endpoints of biological processes can identify the contributions of genetic predisposition and environmental factors to the development of common diseases. Studies applying controlled physiological challenges can reveal dysregulation in metabolic responses that may be predictive for or associated with these diseases. However, large-scale epidemiological studies with well controlled physiological challenge conditions, such as extended fasting periods and defined food intake, pose logistic challenges. Culturally and religiously motivated behavioral patterns of life style changes provide a natural setting that can be used to enroll a large number of study volunteers. Here we report a proof of principle study conducted within a Muslim community, showing that a metabolomics study during the Holy Month of Ramadan can provide a unique opportunity to explore the pre-prandial and postprandial response of human metabolism to nutritional challenges. Up to five blood samples were obtained from eleven healthy male volunteers, taken directly before and two hours after consumption of a controlled meal in the evening on days 7 and 26 of Ramadan, and after an over-night fast several weeks after Ramadan. The observed increases in glucose, insulin and lactate levels at the postprandial time point confirm the expected physiological response to food intake. Targeted metabolomics further revealed significant and physiologically plausible responses to food intake by an increase in bile acid and amino acid levels and a decrease in long-chain acyl-carnitine and polyamine levels. A decrease in the concentrations of a number of phospholipids between samples taken on days 7 and 26 of Ramadan shows that the long-term response to extended fasting may differ from the response to short-term fasting. The present study design is scalable to larger populations and may be extended to the study of the metabolic response in defined patient groups such as individuals with type 2 diabetes. PMID:24906381

2014-01-01

100

Fasting induces a biphasic adaptive metabolic response in murine small intestine  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The gut is a major energy consumer, but a comprehensive overview of the adaptive response to fasting is lacking. Gene-expression profiling, pathway analysis, and immunohistochemistry were therefore carried out on mouse small intestine after 0, 12, 24, and 72 hours of fasting. Results Intestinal weight declined to 50% of control, but this loss of tissue mass was distributed proportionally among the gut's structural components, so that the microarrays' tissue base remained unaffected. Unsupervised hierarchical clustering of the microarrays revealed that the successive time points separated into distinct branches. Pathway analysis depicted a pronounced, but transient early response that peaked at 12 hours, and a late response that became progressively more pronounced with continued fasting. Early changes in gene expression were compatible with a cellular deficiency in glutamine, and metabolic adaptations directed at glutamine conservation, inhibition of pyruvate oxidation, stimulation of glutamate catabolism via aspartate and phosphoenolpyruvate to lactate, and enhanced fatty-acid oxidation and ketone-body synthesis. In addition, the expression of key genes involved in cell cycling and apoptosis was suppressed. At 24 hours of fasting, many of the early adaptive changes abated. Major changes upon continued fasting implied the production of glucose rather than lactate from carbohydrate backbones, a downregulation of fatty-acid oxidation and a very strong downregulation of the electron-transport chain. Cell cycling and apoptosis remained suppressed. Conclusion The changes in gene expression indicate that the small intestine rapidly looses mass during fasting to generate lactate or glucose and ketone bodies. Meanwhile, intestinal architecture is maintained by downregulation of cell turnover.

Evelo Chris TA

2007-10-01

 
 
 
 
101

Modelling of tokamak discharges with the fast central response to the boundary plasma perturbations  

International Nuclear Information System (INIS)

One of the fundamental phenomena in tokamak plasmas is the fast propagation of electron temperature perturbation from the boundary to the plasma core (faster than the characteristic transport time). This phenomenon has been observed in different tokamak (and stellarator) experiments: fast plasma core response to the L-H mode transition, fast cold pulse propagation after laser impurity ablation or deuterium pellet injection and some others. Standard diffusive model of local turbulent transport fails to describe these phenomena. It was the reason for the conclusion on a non-local nature of transport in tokamaks. Results of detailed simulations of some discharges with the fast central responses to the boundary perturbations of different nature are presented in this work. Role of different transport mechanisms is investigated. modelling was performed by the ASTRA transport code. The model takes into consideration the behavior of the plasma neutral component and neutrals recycling at the wall. It is shown that the effect of fast central response in discharges under consideration can be explained without the assumption on the non-local character of transport processes in tokamaks. This effect may be attributed to the behavior of the neutral plasma component, which propagation time across the plasma column is sufficiently short (less than 100 ? s). A rapid change in the neutral flux into the plasma column may somewhat affect the plasma energy balance in the whole plasma cross section almost simultaneously. For example, the rapid electron temperature increase in the plasma core after the fast L-H mode transition can be explained by the reduction of the cold electron source caused by the decrease of neutral flux in plasma. An opposite effect of fast drop of the core electron temperature after deuterium pellet injection may be explained by the rise of deuterium atom density in the plasma core with corresponding increase of ionization source of cold electrons. So, the neutral plasma component is responsible for the visible coupling plasma edge and the core in considered experiments in time interval just after events. (author)

102

Response time of nuclear plant RTDs  

International Nuclear Information System (INIS)

Resistance temperature detectors (RTDs) are used for safety-related measurements in nuclear power plants and must therefore respond to temperature changes in a timely fashion. Experience has shown that RTD response time degradation can occur with aging. Therefore, periodic response time testing is performed to ensure that the acceptable response time limits are not exceeded. Periodic tests performed over the last 9 yr have revealed unacceptable response times for a number of RTDs in several nuclear power plants. This paper presents the laboratory and field experience with response time testing of nuclear plant RTDs

103

Seismic response analysis of the PEC fast reactor building  

International Nuclear Information System (INIS)

In order to compute the motion induced by the design earthquakes at the vessel supporting structure, a seismic response analysis was performed for the PEC fast reactor, taking into account the effects of soil-structure interaction by use of experimentally determined soil parameters. The main aim of he analysis was to evaluate the safety margins present in the design calculations. A detailed 3D finite element model was set up for fixed base analysis; from the results of the 3D model a simplified equivalent model of the structure was then derived for soil-structure interaction analysis. The mathematical model was validated and calibrated by using the results of the experimental dynamic tests performed on the reactor building. The results have shown the adequacy of the computation methodologies, and in particular of those on the use of the equivalent model. (author)

104

Sensitivity of fast-response nanographite photodetector at high temperature  

Science.gov (United States)

We studied performance of a fast-response nanographite film photodetector (PD) in the temperature range of 300- 1000 K. In experiment, we measured the magnitude of the electric signal generated in nanographite film (NGF) under irradiation of intense nanosecond laser pulses at ?=1.064 ?m. In vacuum, the measurements of the PD sensitivity were performed in the temperature range of 300-800 K. We showed experimentally that the PD sensitivity at 300 K was about 30% higher than that at 625 K and 50% higher than that at 740 K. At T>625 K, the magnitude of the light-induced signal decreases as a linear function of temperature and vanish at T ~ 1000 K. In atmospheric conditions, we observed a stable operation of the NGF-based PD during several tens of hours in the temperature range from 300 to 580 K. However, at higher temperature, degradation of the NG film resulted in a drop in the PD sensitivity.

Mikheev, Gennady M.; Zonov, Ruslan G.; Obraztsov, Alexander N.; Svirko, Yuri P.

2009-05-01

105

Supersensitive, fast-response nanowire sensors by using Schottky contacts.  

Science.gov (United States)

A Schottky barrier can be formed at the interface between a metal electrode and a semiconductor. The current passing through the metal-semiconductor contact is mainly controlled by the barrier height and barrier width. In conventional nanodevices, Schottky contacts are usually avoided in order to enhance the contribution made by the nanowires or nanotubes to the detected signal. We present a key idea of using the Schottky contact to achieve supersensitive and fast response nanowire-based nanosensors. We have illustrated this idea on several platforms: UV sensors, biosensors, and gas sensors. The gigantic enhancement in sensitivity of up to 5 orders of magnitude shows that an effective usage of the Schottky contact can be very beneficial to the sensitivity of nanosensors. PMID:20517870

Hu, Youfan; Zhou, Jun; Yeh, Ping-Hung; Li, Zhou; Wei, Te-Yu; Wang, Zhong Lin

2010-08-10

106

High resolution fast neutron spectrometry without time-of-flight  

International Nuclear Information System (INIS)

Performance tests of a spectrometer tube of the type developed by Cuttler and Shalev show that the measurement of fast neutron spectra with this device can be made with an energy resolution previously obtainable only in large time-of-flight facilities. In preliminary tests, resolutions of 16.4 keV for thermal neutrons and 30.9 keV for 1-MeV neutrons were obtained. A broad-window pulse-shape discrimination (PSD) system is used to remove from pulse-height distributions most of the continua due to 3He-recoil events, noise, and wall effect. Use of PSD improved the energy resolution to 12.9 keV for thermal neutrons and 29.2 keV for 1-MeV neutrons. The detector is a viable tool for neutron research at nominally equipped accelerator laboratories

107

Fast, Linear Time Hierarchical Clustering using the Baire Metric  

CERN Document Server

The Baire metric induces an ultrametric on a dataset and is of linear computational complexity, contrasted with the standard quadratic time agglomerative hierarchical clustering algorithm. In this work we evaluate empirically this new approach to hierarchical clustering. We compare hierarchical clustering based on the Baire metric with (i) agglomerative hierarchical clustering, in terms of algorithm properties; (ii) generalized ultrametrics, in terms of definition; and (iii) fast clustering through k-means partititioning, in terms of quality of results. For the latter, we carry out an in depth astronomical study. We apply the Baire distance to spectrometric and photometric redshifts from the Sloan Digital Sky Survey using, in this work, about half a million astronomical objects. We want to know how well the (more costly to determine) spectrometric redshifts can predict the (more easily obtained) photometric redshifts, i.e. we seek to regress the spectrometric on the photometric redshifts, and we use clusterwi...

Contreras, Pedro

2011-01-01

108

Fast Turbo Codes Concatenated With Space-Time Block Codes  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, we investigate a new method for turbo codes which is dividing turbo encoder and decoder into several parallel coding and decoding blocks. These blocks work simultaneously and yield to much faster coding scheme in comparison with classical turbo codes. We compare simulation results of these new turbo codes with classical turbo codes to demonstrate that their performance is comparable with classical turbo codes, albeit they are much faster. Also, we introduce a new system by concatenating this fast turbo coding as outer code with Alamouti`s G2 space-time block coding scheme as inner code to achieve the benefits of both techniques including acceptable diversity and coding gain as well as short coding delay. We consider the performance of this new system in the block Rayleigh fading channel.

Fatemeh Afghah

2008-01-01

109

Fast minute magnetic field coil for time-resolved nanospintronics  

CERN Document Server

Nanospintronic and related research often requires the application of fast rising magnetic field pulses in the plane of the studied planar structure. We have designed and fabricated sub-milimeter-sized coils capable of delivering pulses of the magnetic field up to ~ 500 Oe in the plane of the sample with the rise time of order of 10 ns. The placement of the sample above the coil allows for an easy access to its surface with manipulators or light beams for, e.g., Kerr microscopy. We use the fabricated coil to drive magnetic domain walls in 1 ${\\mu}$ m wide permalloy wires and measure magnetic domain wall velocity as a function of the applied magnetic field.

Pawliszak, ?ukasz; Zgirski, Maciej

2014-01-01

110

A time-dependent study of fast neutrons in iron  

International Nuclear Information System (INIS)

Using diffusion theory and the eigenfunction expansion method, a detailed time-dependent study of fast neutrons has been made for three iron assemblies: infinite, 1 m3, and 0.5 m3. Various results have been obtained by taking two different source energies, namely, 14.47 and 1.0076 MeV. All the calculations have been carried out using the 50-group cross-section set of Ahmed et al. For the 1.0076 MeV source, the time-dependent spectra exhibit two distinct peaks up to about 50 ns, energy variation of the mean slowing down time t /sup i/ /sub s/ shows ''anomalous'' behavior similar to that observed by Beynon et al., and the most probable time t /sup i/ /sub p/ has two different values for some energy groups below about 240 keV, in conformity with the results of White et al. The double values of t /sup i/ /sub p/ (except for the 40th and 41st groups) and the ''anomalous'' behavior observed in t /sup i/ /sub s/ cease when we take the source energy to be 14.47 MeV. Further, for all values of energy E /sup i/, the values of both t /sup i/ /sub s/ and t /sup i/ /sub p/ decrease as the size of the assembly is reduced. It has been shown that in the two larger assemblies, pseudoasymptotic conditions are established in certain time intervals. It was determined that some energy groups tend to cluster and decay with the same decay constant after a certain time

111

On fast and slow times in models with diffusion  

CERN Document Server

The linear Kelvin{Voigt operator L_\\epsilon is a typical example of wave operator L_0 perturbed by higher-order viscous terms as \\epsilonu_xxt. If P\\epsilon is a prefixed boundary value problem for L_\\epsilon, when \\epsilon = 0, L_\\epsilon turns into L_0 and P_\\epsilon into a problem P_0 with the same initial{boundary conditions of P\\epsilon. Boundary layers are missing and the related control terms depending on the fast time are negligible. In a small time interval, the wave behavior is a realistic approximation of u_\\epsilon when \\epsilon \\rightarrow 0. On the contrary, when t is large, diffusion effects should prevail and the behavior of u_\\epsilon for \\epsilon \\rightarrow 0 and t \\rightarrow 1 should be analyzed. For this, a suitable functional correspondence between the Green functions G_\\epsilon and G_0 of P_epsilon and P_0 is derived and its asymptotic behavior is rigorously examined. As a consequence, the interaction between diffusion effects and pure waves is evaluated by means of the slow time \\epsi...

De Angelis, M; Renno, P

2012-01-01

112

Is Fasting Duration Important in Post Adenotonsillectomy Feeding Time?  

Science.gov (United States)

Background: Adenotonsillectomy is a common otolaryngology surgery. Nausea and vomiting are the most common complications of this procedure with a prevalence ranging from 49% to 73 %. Objectives: Our aim was to evaluate the effects of short time fasting protocol on decreasing postoperative pain, nausea and vomiting, and initiation of oral feeding after adenotonsillectomy. Patients and Methods: 120 children aged 4 to 14 years candidates for adenotonsillectomy were randomly divided into intervention and control groups (n = 120, 60 in each group). Each patient of the intervention group was given oral dextrose 10% as much volume as he could consume at 3 and 6 hours prior to the operation. All the data including pain severity, nausea and vomiting of the patients, the time of oral feeding initiation etc. were gathered in checklists after the operation. Statistical analyses were then performed using Statistical Package for the Social Sciences (SPSS) software version 16. Descriptive statistical methods and mean difference test for independent groups and chi square test or Fisher exact test, and if regression needed model test were applied. A P value of 0.05 or less was considered statistically significant. Results: The amount of Acetaminophen administered for the intervention group was significantly lower than the control group, and also the time of oral feeding initiation was significantly shorter in the intervention group than the control group (P < 0.005). Pain severity at all occasions following surgery was significantly lower in the intervention group than the control group (P < 0.001). Although frequency of nausea at recovery time was significantly lower in the intervention group than the control group (P < 0.002), there were no significant differences in frequency of nausea between the two groups at other postoperative occasions. Postoperative vomiting frequency was not significant between the two groups at any occasions. Conclusions: The findings of this survey showed that shortening the duration of pre-adenotonsillectomy fasting period and hydration of patients several hours prior to the operation might be effective in decreasing postoperative pain and facilitating postoperative oral feeding initiation. Nevertheless this method does not seem to prevent postoperative nausea and vomiting. PMID:24660151

Jabbari Moghaddam, Yalda; Seyedhejazi, Mahin; NaderPour, Mosoud; Yaghooblua, Yoosef; Golzari, Samad

2014-01-01

113

Bubble masks for time-encoded imaging of fast neutrons.  

Energy Technology Data Exchange (ETDEWEB)

Time-encoded imaging is an approach to directional radiation detection that is being developed at SNL with a focus on fast neutron directional detection. In this technique, a time modulation of a detected neutron signal is induced-typically, a moving mask that attenuates neutrons with a time structure that depends on the source position. An important challenge in time-encoded imaging is to develop high-resolution two-dimensional imaging capabilities; building a mechanically moving high-resolution mask presents challenges both theoretical and technical. We have investigated an alternative to mechanical masks that replaces the solid mask with a liquid such as mineral oil. Instead of fixed blocks of solid material that move in pre-defined patterns, the oil is contained in tubing structures, and carefully introduced air gaps-bubbles-propagate through the tubing, generating moving patterns of oil mask elements and air apertures. Compared to current moving-mask techniques, the bubble mask is simple, since mechanical motion is replaced by gravity-driven bubble propagation; it is flexible, since arbitrary bubble patterns can be generated by a software-controlled valve actuator; and it is potentially high performance, since the tubing and bubble size can be tuned for high-resolution imaging requirements. We have built and tested various single-tube mask elements, and will present results on bubble introduction and propagation as a function of tubing size and cross-sectional shape; real-time bubble position tracking; neutron source imaging tests; and reconstruction techniques demonstrated on simple test data as well as a simulated full detector system.

Brubaker, Erik; Brennan, James S.; Marleau, Peter; Nowack, Aaron B.; Steele, John; Sweany, Melinda; Throckmorton, Daniel J.

2013-09-01

114

Modeling of Responses and Response Times with the Package cirt  

Directory of Open Access Journals (Sweden)

Full Text Available In computerized testing, the test takers’ responses as well as their response times on the items are recorded. The relationship between response times and response accuracies is complex and varies over levels of observation. For example, it takes the form of a tradeoff between speed and accuracy at the level of a fixed person but may become a positive correlation for a population of test takers. In order to explore such relationships and test hypotheses about them, a conjoint model is proposed. Item responses are modeled by a two-parameter normal-ogive IRT model and response times by a lognormal model. The two models are combined using a hierarchical framework based on the fact that response times and responses are nested within individuals. All parameters can be estimated simultaneously using an MCMC estimation approach. A R-package for the MCMC algorithm is presented and explained.

Jean-Paul Fox

2007-02-01

115

A measurement of the response to fast neutrons of several materials dosemeters  

International Nuclear Information System (INIS)

The response to fast neutrons was measured for three types of materials testing dosemeters: fast neutron dosimetry silicon diodes; beryllia, alumina and calcium fluoride TLDs; graphite walled ionisation chambers. The calibrations were made using a 3MW positive ion accelerator. The arrangement of the target, beam monitor and devices is described, and the measured fast neutron sensitivities are presented. (UK)

116

Response of a single-crystal diamond detector to fast neutrons  

International Nuclear Information System (INIS)

Bi-parametric (neutron time of flight and deposited energy) measurements using a Single-crystal Diamond Detector (4.5 × 4.5 × 0.5 mm3 active volume) were performed at the nTOF neutron facility at CERN. The time structure of the neutron beam combined with the long flight path allowed for measurements of the diamond detector response to quasi monoenergetic neutrons in the energy range up to 40 MeV. Deposited energy spectra were compared to MCNPX simulations using different cross section libraries. The results can be used for the interpretation of Single-crystal Diamond Detector measurements of fast neutrons at spallation neutron sources

117

Response of a single-crystal diamond detector to fast neutrons  

Science.gov (United States)

Bi-parametric (neutron time of flight and deposited energy) measurements using a Single-crystal Diamond Detector (4.5 × 4.5 × 0.5 mm3 active volume) were performed at the n_TOF neutron facility at CERN. The time structure of the neutron beam combined with the long flight path allowed for measurements of the diamond detector response to quasi monoenergetic neutrons in the energy range up to 40 MeV. Deposited energy spectra were compared to MCNPX simulations using different cross section libraries. The results can be used for the interpretation of Single-crystal Diamond Detector measurements of fast neutrons at spallation neutron sources.

Rebai, M.; Milocco, A.; Giacomelli, L.; Perelli Cippo, E.; Tardocchi, M.; Fazzi, A.; Pietropaolo, A.; Gorini, G.

2013-10-01

118

A new timing calibration system of fast-timing detectors using blue-LED  

International Nuclear Information System (INIS)

A new timing calibration system has been developed using Blue-LED for monitoring time-offset value of fast-timing scintillation counters by Tibet EAS collaboration. It is composed of CAMAC-DAC, TKO-Buffer, Blue-LED and LED-amp. Angular resolution of Tibet II EAS array equipped with this system is about 0.5 degree for more than 30 TeV air shower. In addition, it can monitor the temperature around PMT and can be enlarged easily

119

Using ferrite as a fast switch for improving rise time of IPNS extraction kicker  

International Nuclear Information System (INIS)

The Kicker system is used to extract beam from the Rapid Cycling Synchrotron (RCS). The Kicker consists of four identical pulse circuits, each providing over 3.8 kA to each magnet winding. The magnet length is restricted to the space between vacuum bellows attached to the ring magnets. This leaves 0.89 m for the magnet. To keep the voltage low the magnet conductor is broke up into 4, 1/4-turn magnet windings. Each pulse circuit consists of a Pulse Forming Network (PFN) that is charged to 50 KV. The PFN is discharged through a thyratron into a 6.3-ohm transmission line to one of the magnet windings. Our system has always had marginal rise time of around 100 ns. Although the thyratron switching time is much faster than this, losses in the transmission lines cause the slower response. By using ferrite to make a fast switch between the transmission lines and the magnet, the rise time in the magnet can be reduced. To make a fast ferrite switch, the saturation point must carefully be chosen. Parameters related to choosing the proper ferrite to provide fast saturation, at the correct current will be discussed.

120

Plamsa leptin response to acute fasting and refeeding in untreated women with bulimia nervosa.  

Science.gov (United States)

Leptin is known to regulate body weight, energy balance, and reproduction. Therefore, investigation of its physiology is of obvious interest in bulimia nervosa (BN), an eating disorder characterized by body weight-related psychopathology, acute changes in the energy balance, and reproductive alterations. To date, the few studies that have assessed leptin production in BN have had several limitations, including the measurement of blood leptin levels in treated patients and the lack of normal weight healthy controls, so that the information they provide is not conclusive. As the investigation of leptin dynamics is likely to be more informative, we decided to assess leptin response to acute fasting and refeeding in both untreated patients with BN and healthy controls. Twelve women meeting the diagnostic criteria for BN of the Diagnostic and Statistical Manual of Mental Disorders, and 10 healthy women of the same age range participated in a 3-day study. At 1800 h on day 1, they received a meal of 1088 Cal, with 53% carbohydrates, 17% protein, and 30% fat. Then, they fasted until 1800 h on day 2, when they received the same meal. On day 3, they received a standard hospital diet of 2600 Cal, divided into 3 meals, with the same percentages of nutrients as described above. Blood samples were collected at different time points for plasma leptin, glucose, and insulin measurements. In bulimic patients, plasma leptin values were significantly lower than in healthy women (P < 0.0001) and were positively related to body weight, expressed as body mass index (r = 0.86; P < 0.0001). The leptin response to the fasting/refeeding paradigm significantly differed between patients and controls (time x group interaction, P < 0.0001). In fact, in healthy subjects, acute fasting induced a 58% decline in the plasma leptin concentration, whereas such a decrease was only 7% in bulimic women (P < 0.001). After acute refeeding, plasma leptin increased in both groups, although in the patients it did not reach the absolute values observed in normal controls. No significant difference was observed between bulimics and controls in plasma insulin response to the fasting/refeeding paradigm, whereas an abnormal increase in blood glucose levels was observed in the patients after the first meal following acute fasting. We conclude that in untreated women with BN, leptin, despite its very low plasma values, still holds its function as a sensor of body weight changes, but loses its role of signaling acute changes in energy balance. PMID:10902800

Monteleone, P; Bortolotti, F; Fabrazzo, M; La Rocca, A; Fuschino, A; Maj, M

2000-07-01

 
 
 
 
121

Fast and accurate calculations for cumulative first-passage time distributions in Wiener diffusion models  

DEFF Research Database (Denmark)

We propose an improved method for calculating the cumulative first-passage time distribution in Wiener diffusion models with two absorbing barriers. This distribution function is frequently used to describe responses and error probabilities in choice reaction time tasks. The present work extends related work on the density of first-passage times [Navarro, D.J., Fuss, I.G. (2009). Fast and accurate calculations for first-passage times in Wiener diffusion models. Journal of Mathematical Psychology, 53, 222-230]. Two representations exist for the distribution, both including infinite series. We derive upper bounds for the approximation error resulting from finite truncation of the series, and we determine the number of iterations required to limit the error below a pre-specified tolerance. For a given set of parameters, the representation can then be chosen which requires the least computational effort.

Blurton, S.P.; Kesselmeier, M.

2012-01-01

122

Digitally Controlled Point of Load Converter with Very Fast Transient Response  

DEFF Research Database (Denmark)

This paper presents a new Digital Self-Oscillating Modulator (DiSOM) that allows the duty cycle to be changed instantly. The DiSOM modulator is shown to have variable switching that is a function of the duty cycle. Compared to a more traditional digital PWM modulator based on a counter and comparator the DiSOM modulator allows the sampling frequency of the output voltage control loop to be higher than the switching frequency of the power converter, typically a DC/DC converter. The features of the DiSOM modulator makes it possible to design a digitally controlled DC/DC converter with linear voltage mode control and very fast transient response. The DiSOM modulator is combined with a digital PID compensator algorithm is implemented in a hybrid CPLD/FPGA and is used to control a synchronous Buck converter, which is used in typical Point of Load applications. The computational time is only three clock cycles from the time the A/D converter result is read by the control algorithm to the time the duty cycle command is updated. A typical POL converter has been built and the experimental results show that the transient response of the converter is very fast. The output voltage overshoot is only 2.5% of the nominal output voltage when a load step of 50% - 100% of nominal output current is applied to the converter. The settling time is approximately 8 PWM cycles.

Jakobsen, Lars TØnnes; Andersen, Michael Andreas E.

2007-01-01

123

A LaBr3: Ce fast-timing array for DESPEC at FAIR  

Science.gov (United States)

The design of a fast-timing ?-ray detection array aimed at measuring sub-nanosecond half-lives using LaBr3:Ce scintillation crystals is presented. This array will complement novel and existing charged particle and neutron detector arrays at the low-energy branch of a fragment separator (Super-FRS) to be built within the NuSTAR collaboration as part of the future Facility for Anti-proton and Ion Research (FAIR). The array will be used in conjunction with the Advanced Implantation Detector Array (AIDA), to measure implant-decay correlations. Monte-Carlo simulations have been performed to determine the design of the proposed fast-timing array around a localised implantation point. In particular, simulations were used to determine the full-energy peak efficiencies for single cylindrical, conical and 'hybrid' detector geometries, as well as complete array configurations of 'hybrid' and ?1.5 in.×2 in. cylindrical crystals. Timing precision calculations were then used to determine the timing response for each configuration based on its simulated efficiency. An informed decision based on the simulated efficiencies and timing precision calculations allowed the optimum configuration for the array to be determined.

Roberts, Oliver J.; Bruce, Alison M.; Regan, Patrick H.; Podolyák, Zsolt; Townsley, Christopher M.; Smith, John F.; Mulholland, Kieran F.; Smith, Andrew

2014-06-01

124

Mathematical modeling of the LCD response time  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Techniques to reduce LCD motion blur are extensively used in industry and they depend on an inherent LCD parameter: response time. However, normative response time is not a sufficient reference to improve LCD performance and all the gray-to-gray response-time quantities are required to obtain good improvement. However, measuring and gathering all the gray-to-gray transitions takes an excessive amount of time. Consequently, we propose a novel LCD model to simulate as well as compute gray-to-gr...

2007-01-01

125

Interlock system with fast response against sudden foil rupture and vacuum failure in Linac structure  

International Nuclear Information System (INIS)

A 10 MeV electron Linac is operational at Raja Ramanna Centre for Advanced Technology, Indore. To extract the intense electron beam from vacuum to atmosphere, it is scanned inside a vacuum chamber sealed with titanium foil at the exit. If scanning locks fails during high power operation at 200-300 Hz pulse repetition rate, the un-scanned beam will burn a hole in the window, leading to sudden failure of linac vacuum. Under such accidental situation, if subsequent RF pulse is delivered to the linac, the structure will get damaged. The interlocks used for vacuum failure detection are generally taken from the head of cold cathode gauge, which has large response time, hence not effective to protect linac under such accidental condition. We have carried out a series of experiments to simulate the process of accidental vacuum failure and investigated various methods for fast detection of vacuum failure and subsequent inhibition of RF pulses. The response time of the interlock from the vacuum gauge was measured to be 160 ms. Response of the analog output signal of gauge controller corresponding to change in vacuum is relatively fast but takes 20-30 ms to reflect measurable change in analog value. The ion current of the SIP is found very sensitive towards vacuum and responds very fast for any change in the vacuum level. An interlock circuit has been designed which senses the ion current signal of SIP and stops the master trigger system of the linac in less than 3 ms after rupture of the foil. Results of the experiments and design details of the interlock system are presented in this paper. (author)

126

Study on time response of fission gamma-ray detector  

International Nuclear Information System (INIS)

Fission gamma-ray detector using 235U or 238U as detection medium is a new-type detector for pulsed fission neutrons measurement, and it is developed for the first time in our country. Based on its working principle and equivalent circuit, the pulsed current g0(t) delivered from the detector's cathode induced by ? pulsed radiation is obtained with Monte Carlo simulation calculation. On the other hand,the pulsed current gRLC (t) delivered from the detector in output circuit is obtained from some experiments. We finally obtain the time response of the detector: rise time ?0.72 ns, fall time ?3.9 ns, FWHM ?2.08 ns, and the detector's time-response is very fast. The influences of the detector's time-response on the primary waveforms which have different time characteristics are also studied. The results show: the slower the primary waveforms, the smaller influences. If the primary waveform is Gaussian curve which FWHM is 100 ns, the influences of amplitude (A), rise time (tr), fall time(tf), and FWHM (t1/2) are less than 2%. So the fission gamma-ray detector can be used to measure the rapidly changing pulsed fission neutrons, and the measurement results don't need any deconvolution calculations. (authors)

127

Photometer used for response time measurement  

Science.gov (United States)

Photometer detects motion for measuring response speed and acceleration of servocontrol system. Instrument senses selected output movement shortly after operator activates hand-controlled input. Time delay is measured on X/T recorder and response calculated. With suitable motion targets, photometer measures any open- or closed-loop servoresponse and servorate or computer lag without system disturbance.

Da Silva, A. J.

1981-01-01

128

Optimization attempts for time resolution in fast-slow coincidence systems  

International Nuclear Information System (INIS)

A systematic investigation to obtain good time resolutions with proper shape of the resolution curve in fast-slow coincidence systems is described. Measuring the output time-walk as a function of the input signal amplitude for fast timing discriminators, it was possible to choose an input signal amplitude range resulting in small time uncertainty and thus to achieve a good time resolution almost independent of the dynamic range. With an additional fast gating line a more gaussian shape of the resolution curve with less pronounced tails on both sides could be obtained

129

A fasting-responsive signaling pathway that extends life span in C. elegans.  

Science.gov (United States)

Intermittent fasting is one of the most effective dietary restriction regimens that extend life span in C. elegans and mammals. Fasting-stimulus responses are key to the longevity response; however, the mechanisms that sense and transduce the fasting stimulus remain largely unknown. Through a comprehensive transcriptome analysis in C. elegans, we find that along with the FOXO transcription factor DAF-16, AP-1 (JUN-1/FOS-1) plays a central role in fasting-induced transcriptional changes. KGB-1, one of the C. elegans JNKs, acts as an activator of AP-1 and is activated in response to fasting. KGB-1 and AP-1 are involved in intermittent fasting-induced longevity. Fasting-induced upregulation of the components of the SCF E3 ubiquitin ligase complex via AP-1 and DAF-16 enhances protein ubiquitination and reduces protein carbonylation. Our results thus identify a fasting-responsive KGB-1/AP-1 signaling pathway, which, together with DAF-16, causes transcriptional changes that mediate longevity, partly through regulating proteostasis. PMID:23352664

Uno, Masaharu; Honjoh, Sakiko; Matsuda, Mitsuhiro; Hoshikawa, Haruka; Kishimoto, Saya; Yamamoto, Tomohito; Ebisuya, Miki; Yamamoto, Takuya; Matsumoto, Kunihiro; Nishida, Eisuke

2013-01-31

130

Fast response thin-film thermistor for measurements in ocean waters  

Science.gov (United States)

This work describes a very fast thin-film thermistor for temperature measurements in aggressive and conducting liquids. In order to minimize the thermal mass of the sensor, we employed a thin-gauge hollow glass capillary as both a hermetic encapsulation as well as substrate for the thin resistive film. The thermistor thin film is deposited onto an inner surface of the capillary using a solution deposition technique. Microscopic electrical wires are deeply inserted into the capillary tube and fused to the thermistor film. The resistance element thus fabricated is attached to the supporting members and sealed at the open ends. Consequently, detrimental influence of the massive prongs on the dynamic characteristics of the sensor was also eliminated. The prototype temperature probes were compared to the fastest commercially available bead thermistors (with response time of 7milliseconds). The new sensors exhibited superior temporal response.

Kukuruznyak, Dmitry A.; Miller, Jack B.; Gregg, Michael C.; Ohuchi, Fumio S.

2005-02-01

131

Nanorod-Based Fast-Response Pressure-Sensitive Paints  

Science.gov (United States)

A proposed program of research and development would be devoted to exploitation of nanomaterials in pressuresensitive paints (PSPs), which are used on wind-tunnel models for mapping surface pressures associated with flow fields. Heretofore, some success has been achieved in measuring steady-state pressures by use of PSPs, but success in measuring temporally varying pressures has been elusive because of the inherent slowness of the optical responses of these materials. A PSP contains a dye that luminesces in a suitable wavelength range in response to photoexcitation in a shorter wavelength range. The luminescence is quenched by oxygen at a rate proportional to the partial pressure of oxygen and thus proportional to the pressure of air. As a result, the intensity of luminescence varies inversely with the pressure of air. The major problem in developing a PSP that could be easily applied to a wind-tunnel model and could be useful for measuring rapidly varying pressure is to provide very high gas diffusivity for rapid, easy transport of oxygen to and from active dye molecules. Most PSPs include polymer-base binders, which limit the penetration of oxygen to dye molecules, thereby reducing responses to pressure fluctuations. The proposed incorporation of nanomaterials (somewhat more specifically, nanorods) would result in paints having nanostructured surfaces that, relative to conventional PSP surfaces, would afford easier and more nearly complete access of oxygen molecules to dye molecules. One measure of greater access is effective surface area: For a typical PSP as proposed applied to a given solid surface, the nanometer-scale structural features would result in an exposed surface area more than 100 times that of a conventional PSP, and the mass of proposed PSP needed to cover the surface would be less than tenth of the mass of the conventional PSP. One aspect of the proposed development would be to synthesize nanorods of Si/SiO2, in both tangle-mat and regular- array forms, by use of chemical vapor deposition (CVD) and wet chemical processes, respectively. The rods would be coated with a PSP dye, and the resulting PSP signals would be compared with those obtained from PSP dye coats on conventional support materials. Another aspect of the proposed development would be to seek to exploit the quantum properties of nanorods of a suitable semiconductor (possibly GaN), which would be synthesized by CVD. These quantum properties of semiconductor nanorods include narrow-wavelength-band optical absorption and emission characteristics that vary with temperature. The temperature sensitivity might enable simultaneous measurement of fluctuating temperature and pressure and to provide a temperature correction for the PSP response.

Bencic, Timothy; VanderWal, Randall

2007-01-01

132

Hierarchical Bayes Models for Response Time Data  

Science.gov (United States)

Human response time (RT) data are widely used in experimental psychology to evaluate theories of mental processing. Typically, the data constitute the times taken by a subject to react to a succession of stimuli under varying experimental conditions. Because of the sequential nature of the experiments there are trends (due to learning, fatigue,…

Craigmile, Peter F.; Peruggia, Mario; Van Zandt, Trisha

2010-01-01

133

Excessive fasting times: still an underaddressed challenge for African pediatrics and anesthesia?  

Directory of Open Access Journals (Sweden)

Full Text Available Gregor Pollach,1,2 Rose Kapenda,2 Beauty Anusa,2 Ethel Waluza,2 Felix Namboya1,21Department of Anaesthesia and Intensive Care, College of Medicine, University of Malawi, 2Queen Elizabeth Central Hospital, Blantyre, Malawi, Central AfricaBackground: Children are starved before surgery following international preoperative guidelines. Extreme fasting is still reported, but data for Africa are scarce. Starving in hot climates leads to challenges arising from dehydration, hypotension, metabolic disturbances, and complications during induction of anesthesia. The purpose of this study was to evaluate the scope of the problem, identify possible reasons for this, and propose realistic solutions.Methods: We performed eleven prospective audits between 2008 and 2013 in Malawi to improve our preoperative fasting times. In total, 631 children (aged 3 days to 13 years were monitored. Training was provided, and the results were measured using a visual analog scale.Results: In 2008, the baseline audit showed a mean fasting time (MFT of 13.48 hours (31 patients. Training reduced the MFT to 8.77 hours (73 patients and 3.2 hours (35 patients in 2009. Without training, the MFT increased to 4.6 hours (35 patients in 2010 and to 10.2 hours (50 patients in 2011. A low level of training decreased the MFT to 8.13 hours (139 patients, in spring 2012. Educational activity brought the MFT down further to 7.86 hours (36 patients, in summer 2012. Lack of training in autumn 2012 increased MFT to 9.32 hours (151 patients, which then improved to 8.04 hours (27 patients as a result of renewed educational activity. In 2013, MFT increased to 9.8 hours (37 patients despite training. In June 2013, more education achieved a reduction in MFT to 6.52 hours (17 patients. The MFT across all audits (2008–2013 was 8.48 hours. Education reduces MFT, but only in the short term. Factors responsible for changes in MFT were identified.Conclusion: Excessive preoperative fasting is an underaddressed problem in Africa. Reduction is difficult, so it has to be accepted as an ongoing task.Keywords: child, infant, fluid, education, developing countries, Africa, fasting

Pollach G

2014-04-01

134

Time factor and biological response of organism  

International Nuclear Information System (INIS)

The influence of dose distribution in time on biological response of organism is discussed. Blair's model gives the possibility to analyse in a simple way an emergency situation when the whole-body gamma irradiation occurs. A probable construction of the ''time dosimeter'' is proposed. A suitable ''time dosimeter'' might be represented by some modification of the BeO dosimeter, the fading properties of which simulate the recovery properties of organism. (F.G.)

135

Fast Human Brain Magnetic Resonance Responses Associated With Epileptiform Spikes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Neuronal currents produce local electromagnetic fields that can potentially modulate the phase of the magnetic resonance signal and thus provide a contrast mechanism tightly linked to neuronal activity. Previous work has demonstrated the feasibility of direct MRI of neuronal activity in phantoms and cell culture, but in vivo efforts have yielded inconclusive, conflicting results. The likelihood of detecting and validating such signals can be increased with (i) fast gradient-echo echo-planar i...

Sundaram, Padmavathi; Wells, William M.; Bubrick, Ellen J.; Bromfield, Edward B.; Mu?nch, Mirjam; Orbach, Darren B.

2010-01-01

136

Seismic responses of a pool-type fast reactor with different core support designs  

International Nuclear Information System (INIS)

In designing the core support system for a pool-type fast reactor, there are many issues which must be considered in order to achieve an optimum and balanced design. These issues include safety, reliability, as well as costs. Several design options are possible to support the reactor core. Different core support options yield different frequency ranges and responses. Seismic responses of a large pool-type fast reactor incorporated with different core support designs have been investigated. 4 refs., 3 figs

137

Emergency response time optimisation using real-time traffic information  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper describes possible approaches for optimal route selection foremergency vehicles. The presented navigation software’s architectures employ real-time traffic congestion information, matched to a tailored map. Four approaches have been described and reviewed against suitability in emergency response situations.

Jasku?owski, Miros?aw; Kamran, Shoaib; Haas, Olivier

2007-01-01

138

The Fast Tracker Real Time Processor: high quality real-time tracking at ATLAS  

CERN Document Server

As the LHC luminosity is ramped up to the design level of 1x1034 cm?2 s?1 and beyond, the high rates, multiplicities, and energies of particles seen by the detectors will pose a unique challenge. Only a tiny fraction of the produced collisions can be stored on tape and immense real-time data reduction is needed. An effective trigger system must maintain high trigger efficiencies for the most important physics and at the same time suppress the enormous QCD backgrounds. This requires massive computing power to minimize the online execution time of complex algorithms. A multi-level trigger is an effective solution for an otherwise impossible problem. The Fast Tracker (FTK)[1], [2] is a proposed upgrade to the current ATLAS trigger system that will operate at full Level-1 output rates and provide high quality tracks reconstructed over the entire detector by the start of processing in Level-2. FTK is a dedicated Super Computer based on a mixture of advanced technologies. The architecture broadly employs powerf...

Stabile, A; The ATLAS collaboration

2011-01-01

139

Test item response time and the response likelihood  

CERN Document Server

Test takers do not give equally reliable responses. They take different responding strategies and they do not make the same effort to solve the problem and answer the question correctly. The consequences of differential test takers' behavior are numerous: the test item parameters could be biased, there might emerge differential item functioning for certain subgroups, estimation of test taker's ability might have greater error, etc. All the consequences are becoming more prominent at low-stakes tests where test takers' motivation is additionally decreased. We had analyzed a computer based test in Physics and tried to find and describe relationship between the item response time and the item response likelihood. We have found that magnitude of such relationship depends on the item difficulty parameter. We have also noticed that boys, who respond faster, in average, give responses with greater likelihood than the boys who respond slower. The same trend was not detected for girls.

Verbic, Srdjan

2009-01-01

140

Fast ?-ray coincidence timing using a BGO detector array in a nuclear reaction experiment  

International Nuclear Information System (INIS)

The (7Li, 7Be) nuclear charge-exchange reaction has been investigated at E(7Li)=350 MeV. Coincidences were measured between the charged 7Be reaction products in the focal plane of a magnetic spectrometer and 430-keV Doppler-shifted ?-rays from the decay in flight of excited 7Be ejectiles. The latter were detected in a compact BGO detector array. Fast timing was used to optimize the separation between prompt and randoms events. The BGO output signals display the statistical distribution of the arrival times of individual photoelectrons from the photocathode in the photomultiplier tubes. A timing resolution of 6.5 ns relative to the accelerator RF was obtained. A simple model was successfully developed to simulate the BGO output signals with a statistical distribution of a predetermined number of photoelectrons modulated by the light output response of the scintillator and the single-photoelectron gain distribution and transit time through the photomultiplier tube. It is concluded that the timing resolution is primarily limited by the small number of photoelectrons. ((orig.))

 
 
 
 
141

Time Domain Response of the ARIANNA Detector  

CERN Document Server

The Antarctic Ross Ice Shelf Antenna Neutrino Array (ARIANNA) is a high-energy neutrino detector designed to record the Askaryan electric field signature of cosmogenic neutrino interactions in ice. To understand the inherent radio-frequency (RF) neutrino signature, the time-domain response of the ARIANNA RF receiver must be measured. ARIANNA uses Create CLP5130-2N log-periodic dipole arrays (LPDAs). The associated effective height operator converts incident electric fields to voltage waveforms at the LDPA terminals. The effective height versus time and incident angle was measured, along with the associated response of the ARIANNA RF amplifier. The results are verified by correlating to field measurements in air and ice, using oscilloscopes. Finally, theoretical models for the Askaryan electric field are combined with the detector response to predict the neutrino signature.

Barwick, S W; Besson, D Z; Hanson, J C; Klein, S R; Kleinfelder, S A; Piasecki, M; Ratzlaff, K; Reed, C; Roumi, M; Stezelberger, T; Tatar, J; Walker, J; Young, R; Zou, L

2014-01-01

142

Investigation of response time testing requirements  

International Nuclear Information System (INIS)

The purpose of the Response Time Testing (RTT) Program was to determine if requirements for RTT could be eliminated for specific pressure and differential pressure transmitters and switches. This program was initiated when experience and historical data from a significant number of nuclear power plants indicated that, while RTT is both resource and exposure intensive, an insignificant number of pressure sensor failures have been detected through this type of testing. Assessment of plant response time data and performance of Failure Modes and Effects Analysis (FMEA) on sensor hardware were the mechanisms used by the program to determine the redundancy of RTT in conjunction with other required periodic testing (e.g., calibrations, channel checks, surveillance tests). In general, the FMEA results indicated RTT is redundant to other periodic tests. Results of the program identified only two response time failure modes and two manufacturing/handling defects that may not concurrently affect sensor output. The two failure modes affect a limited number of sensor models. Appropriate testing has been identified in cases where response time degradation may not be coincident with significant sensor output change. 14 refs., 19 figs., 39 tabs

143

Improved strain-wire flowmeter has fast response time  

Science.gov (United States)

Strain-sensitive resistance wires in a Wheatstone bridge arrangement form the sensing element of a flowmeter. The change in resistance of the wires is measured as a function of stream velocity. Thus the electrical output is a measure of both rapidly varying and steady fluid-flow rates.

Dillon, R. C.; Dunbar, W. R.

1965-01-01

144

Real time face recognition using adaboost improved fast PCA algorithm  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents an automated system for human face recognition in a real time background world for a large homemade dataset of persons face. The task is very difficult as the real time background subtraction in an image is still a challenge. Addition to this there is a huge variation in human face image in terms of size, pose and expression. The system proposed collapses most of this variance. To detect real time human face AdaBoost with Haar cascade is used and a simple...

Kumar, K. Susheel; Semwal, Vijay Bhaskar; Tripathi, R. C.

2011-01-01

145

Simulation of response functions of fast neutron sensors and development of thin neutron silicon sensor.  

Science.gov (United States)

On radiation detection using silicon sensor, signals are produced from collected charges in a depletion layer; however, for high-energy particles, this depletion layer is extended due to funnelling phenomenon. The lengths of charge collection were experimentally obtained from proton peak energies in measured pulse-heights. The length is extended with increasing proton energy of up to 6 MeV, and then, is constant over 6 MeV. The response functions of fast neutron sensors were simulated for 5- and 15-MeV monoenergetic and (252)Cf neutron sources using the Monte Carlo N-Particle eXtended code. The simulation results agree well with the experimental ones, including the effect of funnelling phenomenon. In addition, a thin silicon sensor was developed for a new real-time personal neutron dosemeter. Photon sensitivity is vanishingly smaller than neutron one by a factor of 5×10(-4). PMID:24516186

Takada, Masashi; Nakamura, Takashi; Matsuda, Mikihiko; Nunomiya, Tomoya

2014-10-01

146

Mixing Snapshots and Fast Time Integration of PDEs  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A local proper orthogonal decomposition (POD) plus Galerkin projection method was recently developed to accelerate time dependent numerical solvers of PDEs. This method is based on the combined use of a numerical code (NC) and a Galerkin sys- tem (GS) in a sequence of interspersed time intervals, INC and IGS, respectively. POD is performed on some sets of snapshots calculated by the numerical solver in the INC inter- vals. The governing equations are Galerkin projected onto the most energetic...

Rapun Banzo, Maria Luisa; Terragni, Filippo; Vega Prada, Jose? Manuel

2011-01-01

147

A Time Series Evaluation of the FAST National Stroke Awareness Campaign in England  

Science.gov (United States)

Objective In February 2009, the Department of Health in England launched the Face, Arm, Speech, and Time (FAST) mass media campaign, to raise public awareness of stroke symptoms and the need for an emergency response. We aimed to evaluate the impact of three consecutive phases of FAST using population-level measures of behaviour in England. Methods Interrupted time series (May 2007 to February 2011) assessed the impact of the campaign on: access to a national stroke charity's information resources (Stroke Association [SA]); emergency hospital admissions with a primary diagnosis of stroke (Hospital Episode Statistics for England); and thrombolysis activity from centres in England contributing data to the Safe Implementation of Thrombolysis in Stroke UK database. Results Before the campaign, emergency admissions (and patients admitted via accident and emergency [A&E]) and thrombolysis activity was increasing significantly over time, whereas emergency admissions via general practitioners (GPs) were decreasing significantly. SA webpage views, calls to their helpline and information materials dispatched increased significantly after phase one. Website hits/views, and information materials dispatched decreased after phase one; these outcomes increased significantly during phases two and three. After phase one there were significant increases in overall emergency admissions (505, 95% CI?=?75 to 935) and patients admitted via A&E (451, 95% CI?=?26 to 875). Significantly fewer monthly emergency admissions via GPs were reported after phase three (?19, 95% CI?=??29 to ?9). Thrombolysis activity per month significantly increased after phases one (3, 95% CI?=?1 to 6), and three (3, 95% CI?=?1 to 4). Conclusions Phase one had a statistically significant impact on information seeking behaviour and emergency admissions, with additional impact that may be attributable to subsequent phases on information seeking behaviour, emergency admissions via GPs, and thrombolysis activity. Future campaigns should be a0ccompanied by evaluation of impact on clinical outcomes such as reduced stroke-related morbidity and mortality. PMID:25119714

Flynn, Darren; Ford, Gary A.; Rodgers, Helen; Price, Christopher; Steen, Nick; Thomson, Richard G.

2014-01-01

148

Time-of-flight measurement of fast neutrons with Timepix detectors  

Science.gov (United States)

Timepix pixel detectors have been used to study the response of silicon hybrid pixel detectors to fast neutrons from a pulsed neutron beam at WNR FP30R, a 14 m long flight path, in the Los Alamos Neutron Science Center. Neutrons with kinetic energies up to 600 MeV were available. In order to enhance the conversion of neutrons to energetic charged particles, several converter foils and filters were attached to the 300 ?m thick silicon sensor, i.e. polyethylene, polyethylene with aluminum, 6LiF, 6LiF with aluminum, aluminum. The Time-of-Arrival mode of the Timepix detectors has permitted the application of the Time-of-Flight (TOF) technique for the assignment of the detected interactions in the form of clusters (groups of adjacent pixels) in the pixel matrix, to the kinetic energies of the incident neutrons. It was found that, for lower neutron energies ( ~ MeV range) the cluster rates below the polyethylene and the polyethylene and aluminum region, produced by recoil protons, are a good measure for the mean kinetic energies of neutrons. For energies above 50 MeV nuclear reactions in the silicon dominate the detector response. In this energy range the shape of the clusters indicates the neutron kinetic energy.

Bergmann, B.; Nelson, R. O.; O'Donnell, J. M.; Pospisil, S.; Solc, J.; Takai, H.; Vykydal, Z.

2014-05-01

149

Pupillary Response & Test Your Reaction Time  

Science.gov (United States)

Students observe and test their reflexes, including the (involuntary) pupillary response and (voluntary) reaction times using their dominant and non-dominant hands, as a way to further explore how reflexes occur in humans. They gain insights into how our bodies react to stimuli, and how some reactions and body movements are controlled automatically, without conscious thought. Using information from the associated lesson about how robots react to situations, including the stimulus-to-response framework, students see how engineers use human reflexes as examples for controls for robots.

GK-12 Program, Computational Neurobiology Center, College of Engineering,

150

Impact of fasting time on hepatic lipid metabolism in nutritional animal studies.  

Science.gov (United States)

Many animal studies on improvement of lipid metabolism, using dietary components, fast the animals on the final day of the feeding. Although fasting has a significant impact on lipid metabolism, its time-dependent influence is not fully understood. We examined the effects of several fasting times on lipid metabolism. Rats fed with a semisynthetic diet for 2 wk were killed after 0 (9:00?am), 6 (7:00?am-1:00?pm), 9 (0:00?am-9:00?am), and 13?h (8:00?pm-9:00?am) of fasting. Compared to the 0?h group, marked reduction of liver weight and hepatic triacylglycerol content was observed in the 9 and 13?h groups. Activities of hepatic enzymes involved in fatty acid synthesis gradually decreased during fasting. In contrast, drastic time-dependent reduction of gene expression, of the enzymes, was observed. Expression of carnitine palmitoyltransferase mRNA was higher in the fasting groups than in the 0?h group. Our study showed that fasting has a significant impact on several parameters related to lipid metabolism in rat liver. PMID:25209508

Ikeda, Ikuo; Metoki, Kanae; Yamahira, Takashi; Kato, Masaki; Inoue, Nao; Nagao, Koji; Yanagita, Teruyoshi; Shirakawa, Hitoshi; Komai, Michio

2014-09-01

151

Fast, real-time, DFT instrument based on VMEbus  

Science.gov (United States)

An emerging class of VMEbus-based test and measurement instruments is benchmarked by a recently introduced digital spectrum analyzer. The instrument performs real-time spectrum analysis in the DC-to-10 MHz range at 5000 spectrums per second. Its architecture is based on the VMEbus and is partly adapted for high-speed pipeline processing. The keyboard and color graphic displays suit basic spectrum analysis, as well as advanced analysis of amplitude vs. both frequency and time. The instrument provides a DSP (digital signal processing) programming environment when an RS232 terminal is attached. With addition of an RF spectrum analyzer, downconverter, and software, real-time analysis is extended to 21 GHz and beyond. Postprocessable spectral output makes the instrument suitable for use in a larger signal analysis or test system. This digital spectrum analyzer, which has 17 boards on the bus, is representative of an emerging class of filled-enclosure instruments.

Snell, Jay

152

A Fast-Time Simulation Tool for Analysis of Airport Arrival Traffic  

Science.gov (United States)

The basic objective of arrival sequencing in air traffic control automation is to match traffic demand and airport capacity while minimizing delays. The performance of an automated arrival scheduling system, such as the Traffic Management Advisor developed by NASA for the FAA, can be studied by a fast-time simulation that does not involve running expensive and time-consuming real-time simulations. The fast-time simulation models runway configurations, the characteristics of arrival traffic, deviations from predicted arrival times, as well as the arrival sequencing and scheduling algorithm. This report reviews the development of the fast-time simulation method used originally by NASA in the design of the sequencing and scheduling algorithm for the Traffic Management Advisor. The utility of this method of simulation is demonstrated by examining the effect on delays of altering arrival schedules at a hub airport.

Erzberger, Heinz; Meyn, Larry A.; Neuman, Frank

2004-01-01

153

Time-to-charge converters for fast encoding and readout ADCs  

International Nuclear Information System (INIS)

Time-to-charge converters have been designed and built as front-end electronics for fast encoding and readout ADCs. The time resolution and long-term stability of these modules are both about 0.1% of the time range selected. (orig.)

154

Achieving a response from fast-growing companies: the case of Slovenian gazelles  

Directory of Open Access Journals (Sweden)

Full Text Available

Non-mandatory business surveys generally suffer from low response rates and potential non-response bias. Achieving a response is most problematic in small- and medium-sized enterprises because of their scarce human resources. The problem becomes exacerbated in fast-growing companies – ‘gazelles’. The paper addresses the effectiveness of data collection efforts to achieve a response among the top Slovenian gazelles in 2008. We analyse the impact on response rates and data quality. Finally, we look for evidence of non-response bias.

Aleša Lotri? Dolinar

2010-11-01

155

Fast and Flexible Multivariate Time Series Subsequence Search  

Science.gov (United States)

Multivariate Time-Series (MTS) are ubiquitous, and are generated in areas as disparate as sensor recordings in aerospace systems, music and video streams, medical monitoring, and financial systems. Domain experts are often interested in searching for interesting multivariate patterns from these MTS databases which often contain several gigabytes of data. Surprisingly, research on MTS search is very limited. Most of the existing work only supports queries with the same length of data, or queries on a fixed set of variables. In this paper, we propose an efficient and flexible subsequence search framework for massive MTS databases, that, for the first time, enables querying on any subset of variables with arbitrary time delays between them. We propose two algorithms to solve this problem (1) a List Based Search (LBS) algorithm which uses sorted lists for indexing, and (2) a R*-tree Based Search (RBS) which uses Minimum Bounding Rectangles (MBR) to organize the subsequences. Both algorithms guarantee that all matching patterns within the specified thresholds will be returned (no false dismissals). The very few false alarms can be removed by a post-processing step. Since our framework is also capable of Univariate Time-Series (UTS) subsequence search, we first demonstrate the efficiency of our algorithms on several UTS datasets previously used in the literature. We follow this up with experiments using two large MTS databases from the aviation domain, each containing several millions of observations. Both these tests show that our algorithms have very high prune rates (>99%) thus needing actual disk access for only less than 1% of the observations. To the best of our knowledge, MTS subsequence search has never been attempted on datasets of the size we have used in this paper.

Bhaduri, Kanishka; Oza, Nikunj C.; Zhu, Qiang; Srivastava, Ashok N.

2010-01-01

156

Continuous data recording on fast real-time systems  

International Nuclear Information System (INIS)

The PCU-Project launched for the enhancement of the vertical stabilisation system at JET required the design of a new real-time control system with the challenging specifications of 2Gops and a cycle time of 50 ?s. The RTAI based architecture running on an x86 multi-core processor technology demonstrated to be the best platform for meeting the high requirements. Moreover, on this architecture thanks to the smart allocation of the interrupts it was possible to demonstrate simultaneous data streaming at 50 MBs on Ethernet while handling a real-time 100 kHz interrupt source with a maximum jitter of just 3 ?s. Because of the memory limitation imposed by 32 bit version Linux running in kernel mode, the RTAI-based new controller allows a maximum practical data storage of 800 MB per pulse. While this amount of data can be accepted for JET normal operation it posed some limitations in the debugging and commissioning of the system. In order to increase the capability of the data acquisition of the system we have designed a mechanism that allows continuous full bandwidth (56 MB/s) data streaming from the real-time task (running in kernel mode) to either a data collector (running in user mode) or an external data acquisition server. The exploited architecture involves a peer to peer mechanisms where the sender running in RTAI kernel mode broadcasts large chunks of data using UDP packets, implemented using the 'fcomm' RTAI extension , to a receiver that will store the data. The paper will present the results of the initial RTAI operating system tests, the design of the streaming architecture and the first experimental results.

157

Fabrication and Characteristics of Fast Photo Response ZnO/Porous Silicon UV Photoconductive Detector  

Directory of Open Access Journals (Sweden)

Full Text Available Fast response time UV photoconductive detector was fabricated based on ZnO film prepared by thermal chemical spray pyrolysis technique. The ZnO nanofilms are grown on the porous silicon (PS nanosurface which has drastically reduced the response time of the ZnO UV detector from few seconds to few hundreds of microseconds. The surface functionalization of the ZnO film deposited on porous silicon (PS layer by polyamide nylon has highly improved the photoresponsivity of the detector to 0.8 A/W. The normalized de-tectivity (D* of the fabricated ZnO UV detector at wavelength of 385 nm is found to be about 2.12 × 1011 cm Hz1/2 W–1. The ZnO film grown on the porous silicon layer was oriented in the c-axis and it is found to be a p-type semiconductor, which is referred to the compensation of the excess charge carriers in the ZnO film by the nanospikes silicon layer.

Hanan A. Thjeel

2011-12-01

158

Ultra-high throughput real-time instruments for capturing fast signals and rare events  

Science.gov (United States)

Wide-band signals play important roles in the most exciting areas of science, engineering, and medicine. To keep up with the demands of exploding internet traffic, modern data centers and communication networks are employing increasingly faster data rates. Wide-band techniques such as pulsed radar jamming and spread spectrum frequency hopping are used on the battlefield to wrestle control of the electromagnetic spectrum. Neurons communicate with each other using transient action potentials that last for only milliseconds at a time. And in the search for rare cells, biologists flow large populations of cells single file down microfluidic channels, interrogating them one-by-one, tens of thousands of times per second. Studying and enabling such high-speed phenomena pose enormous technical challenges. For one, parasitic capacitance inherent in analog electrical components limits their response time. Additionally, converting these fast analog signals to the digital domain requires enormous sampling speeds, which can lead to significant jitter and distortion. State-of-the-art imaging technologies, essential for studying biological dynamics and cells in flow, are limited in speed and sensitivity by finite charge transfer and read rates, and by the small numbers of photo-electrons accumulated in short integration times. And finally, ultra-high throughput real-time digital processing is required at the backend to analyze the streaming data. In this thesis, I discuss my work in developing real-time instruments, employing ultrafast optical techniques, which overcome some of these obstacles. In particular, I use broadband dispersive optics to slow down fast signals to speeds accessible to high-bit depth digitizers and signal processors. I also apply telecommunication multiplexing techniques to boost the speeds of confocal fluorescence microscopy. The photonic time stretcher (TiSER) uses dispersive Fourier transformation to slow down analog signals before digitization and processing. The act of time-stretching effectively boosts the performance of the back-end electronics and digital signal processors. The slowed down signals reach the back-end electronics with reduced bandwidth, and are therefore less affected by high-frequency roll-off and distortion. Time-stretching also increases the effective sampling rate of analog-to-digital converters and reduces aperture jitter, thereby improving resolution. Finally, the instantaneous throughputs of digital signal processors are enhanced by the stretch factor to otherwise unattainable speeds. Leveraging these unique capabilities, TiSER becomes the ideal tool for capturing high-speed signals and characterizing rare phenomena. For this thesis, I have developed techniques to improve the spectral efficiency, bandwidth, and resolution of TiSER using polarization multiplexing, all-optical modulation, and coherent dispersive Fourier transformation. To reduce the latency and improve the data handling capacity, I have also designed and implemented a real-time digital signal processing electronic backend, achieving 1.5 tera-bit per second instantaneous processing throughput. Finally, I will present results from experiments highlighting TiSER's impact in real-world applications. Confocal fluorescence microscopy is the most widely used method for unveiling the molecular composition of biological specimens. However, the weak optical emission of fluorescent probes and the tradeoff between imaging speed and sensitivity is problematic for acquiring blur-free images of fast phenomena and cells flowing at high speed. Here I introduce a new fluorescence imaging modality, which leverages techniques from wireless communication to reach record pixel and frame rates. Termed Fluorescence Imaging using Radio-frequency tagged Emission (FIRE), this new imaging modality is capable of resolving never before seen dynamics in living cells - such as action potentials in neurons and metabolic waves in astrocytes - as well as performing high-content image assays of cells and particles in high-speed flow.

Buckley, Brandon Walter

159

Y2K issues for real time computer systems for fast breeder test reactor  

International Nuclear Information System (INIS)

Presentation shows the classification of real time systems related to operation, control and monitoring of the fast breeder test reactor. Software life cycle includes software requirement specification, software design description, coding, commissioning, operation and management. A software scheme in supervisory computer of fast breeder test rector is described with the twenty years of experience in design, development, installation, commissioning, operation and maintenance of computer based supervision control system for nuclear installation with a particular emphasis on solving the Y2K problem

160

Effect of fasting versus feeding on the bone metabolic response to running.  

Science.gov (United States)

Individuals often perform exercise in the fasted state, but the effects on bone metabolism are not currently known. We compared the effect of an overnight fast with feeding a mixed meal on the bone metabolic response to treadmill running. Ten, physically-active males aged 28 ± 4y (mean ±SD) completed two, counterbalanced, 8d trials. After 3d on a standardised diet, participants performed 60 min of treadmill running at 65% VO(2max) on Day 4 following an overnight fast (FAST) or a standardised breakfast (FED). Blood samples were collected at baseline, before and during exercise, for 3h after exercise, and on four consecutive follow-up days (FU1-FU4). Plasma/serum were analysed for the c-terminal telopeptide region of collagen type 1 (?-CTX), n-terminal propeptides of procollagen type 1 (P1NP), osteocalcin (OC), bone alkaline phosphatase (bone ALP), parathyroid hormone (PTH), albumin-adjusted calcium, phosphate, osteoprotegerin (OPG), cortisol, leptin and ghrelin. Only the ?-CTX response was significantly affected by feeding. Pre-exercise concentrations decreased more in FED compared with FAST (47% vs 26%, PP1NP and PTH increased, and OC decreased during exercise. Bone markers were not significantly different from baseline on FU1-FU4. Fasting had only a minor effect on the bone metabolic response to subsequent acute, endurance exercise, reducing the duration of the increase in ?-CTX during early recovery, but having no effect on changes in bone formation markers. The reduced duration of the ?-CTX response with fasting was not fully explained by changes in PTH, OPG, leptin or ghrelin. PMID:22960044

Scott, Jonathan P R; Sale, Craig; Greeves, Julie P; Casey, Anna; Dutton, John; Fraser, William D

2012-12-01

 
 
 
 
161

Fast neutron dose response of a commercial polycarbonate  

International Nuclear Information System (INIS)

A commercial polycarbonate produced in Brazil is being studied to be used as neutron detector material using Solid State Nuclear Track Detection (SSNTD) method replacing the well-known detector materials Makrofol and CR-39. This technique is based on the damage (tracks) registration of charged particles produced by the interaction of neutrons with carbon and oxygen atoms of some dielectric materials. The IPEN dosimeter prototype is composed by 30x10x1.5 mm3 polycarbonate piece inserted between two Polymethyl Methacralate (PMMA) plates 2 mm thick. The prototypes were irradiated placed on an ISO slab phantom using an isotropic 241AmBe source at LN/LNMRI (Neutrons Laboratory of the National Laboratory of Ionizing Radiation Metrology). To study the dose response groups of five prototypes were irradiated with Hp(10) from 0.5 to 20 mSv with normal incidence and to investigate the angular incidence effect with Hp(10) = 5 mSv with incidence angles of 15o, 45o, 60o, 75o, 85o and 90o. The detectors were revealed by chemical etching with the solution PEW-40 during 3 h. The track density of the detector surface was determined by the average of track counting of five fields (20x0.1 mm2). The track response to equivalent dose Hp(10) showed a good agreement with linear fit in the studied interval. The track density strongly decreases for incidence angles higher than 45 deg

162

Effect of 235U concentration on fast neutron space and time eigenvalues and eigenfunctions in uranium  

International Nuclear Information System (INIS)

The results of a detailed study of a fast neutron diffusion length and pulsed problem in depleted and enriched subcritical uranium assemblies (0.2 to 4% 235U) are reported. The multigroup space- and time-dependent equations are solved using the eigenfunction expansion method. The effect of 235U concentration on space (diffusion length problem) and time (pulsed problem) eigenvalues and eigenfunctions, particularly on the ''discrete'' eigenvalue and eigenfunction, is discussed. The approach to equilibrium (both in space and in time) of fast neutrons changes with changing 235U concentration

163

Effect of short-term fasting on lipolytic responsiveness in normal and obese human subjects  

International Nuclear Information System (INIS)

In this study the rate of lipolysis (fatty acid and glycerol release into blood) has been quantified in both normal weight and obese volunteers after both 15 and 87 h of fasting. In each study, the basal rate and subsequent response to epinephrine infusion were determined. The rate of appearance (R/sub a/) of free fatty acids (FFA) and glycerol were quantified by infusion of [1-13C]palmitate and D-5-glycerol, respectively. Substrate flux rates per unit of body fat mass and lean body mass were calculated from total body water measurements using H218O dilution. In normal volunteers, the basal R/sub a/ FFA and R/sub a/ glycerol rose markedly with 87 h of fasting, whereas the increases were more modest in the obese subjects. However, the rate of mobilization of fat, in relation to the lean body mass, was higher in the obese subjects than in the normal subjects after 15 h of fasting, and the values were similar in both groups after 87 h of fasting. There was an increased lipolytic response to epinephrine after fasting in both groups. This increased sensitivity may have resulted from the enhancement of fatty acid-triglyceride substrate cycling that occurred after fasting

164

Effect of short-term fasting on lipolytic responsiveness in normal and obese human subjects  

Energy Technology Data Exchange (ETDEWEB)

In this study the rate of lipolysis (fatty acid and glycerol release into blood) has been quantified in both normal weight and obese volunteers after both 15 and 87 h of fasting. In each study, the basal rate and subsequent response to epinephrine infusion were determined. The rate of appearance (R/sub a/) of free fatty acids (FFA) and glycerol were quantified by infusion of (1- TC)palmitate and D-5-glycerol, respectively. Substrate flux rates per unit of body fat mass and lean body mass were calculated from total body water measurements using H2 YO dilution. In normal volunteers, the basal R/sub a/ FFA and R/sub a/ glycerol rose markedly with 87 h of fasting, whereas the increases were more modest in the obese subjects. However, the rate of mobilization of fat, in relation to the lean body mass, was higher in the obese subjects than in the normal subjects after 15 h of fasting, and the values were similar in both groups after 87 h of fasting. There was an increased lipolytic response to epinephrine after fasting in both groups. This increased sensitivity may have resulted from the enhancement of fatty acid-triglyceride substrate cycling that occurred after fasting.

Wolfe, R.R.; Peters, E.J.; Klein, S.; Holland, O.B.; Rosenblatt, J.; Gary, H. Jr.

1987-02-01

165

Fasting time and lipid parameters: association with hepatic steatosis -- data from a random population sample  

Science.gov (United States)

Background Current guidelines recommend measuring plasma lipids in fasting patients. Recent studies, however, suggest that variation in plasma lipid concentrations secondary to fasting time may be minimal. Objective of the present study was to investigate the impact of fasting time on plasma lipid concentrations (total cholesterol, HDL and LDL cholesterol, triglycerides). A second objective was to determine the effect of non-alcoholic fatty liver disease exerted on the above-mentioned lipid levels. Method Subjects participating in a population-based cross-sectional study (2,445 subjects; 51.7% females) were questioned at time of phlebotomy regarding duration of pre-phlebotomy fasting. Total cholesterol, LDL and HDL cholesterol, and triglycerides were determined and correlated with length of fasting. An upper abdominal ultrasonographic examination was performed and body-mass index (BMI) and waist-to-hip ratio (WHR) were calculated. Subjects were divided into three groups based on their reported fasting periods of 1–4 h, 4–8 h and?>?8 h. After application of the exclusion criteria, a total of 1,195 subjects (52.4% females) were included in the study collective. The Kruskal-Wallis test was used for continuous variables and the chi-square test for categorical variables. The effects of age, BMI, WHR, alcohol consumption, fasting time and hepatic steatosis on the respective lipid variables were analyzed using multivariate logistic regression. Results At multivariate analysis, fasting time was associated with elevated triglycerides (p?=?0.0047 for 1–4 h and p?=?0.0147 for 4–8 h among females; p?fasting period. LDL cholesterol and triglycerides exhibit highly significant variability; the greatest impact is seen with the triglycerides. Fasting time represents an independent factor for reduced LDL cholesterol and elevated triglyceride concentrations. There is a close association between elevated lipids and hepatic steatosis. PMID:24447492

2014-01-01

166

An eigenvalue and eigenfunction study of time-dependent fast-neutron spectra in 232Th  

International Nuclear Information System (INIS)

The pulsed problem for fast neutrons in Th has been studied using the multigroup diffusion equation and eigenfunction expansion method. The time-dependent fast-neutron spectra have been obtained up to 8000 ns inside Th systems with buckling ranging from 0.0 to 0.015 cm-2. The results have been obtained using the 27-group BARC data set. It has been shown that for a fast Th system, unlike a fast U system, all the time eigenvalues lie in the continuum and no discrete time eigenvalue exists. A fast Th system behaves more like a non-multiplying system. The spectra shift continuously to lower energies with increasing time. However, pseudo-asymptotic conditions are established in certain time intervals. The start of pseudo-equilibrium conditions and the duration for which they persist is seen to increase with decreasing buckling. The reason for the establishment of pseudo-equilibrium conditions has been discussed. The theoretical results for the instantaneous decay constant inside a 40 cm cube of Th have been compared with the experimental results of Moo et al. (1973). The present results are in good agreement with the above experimental results based on the 239Pu detector. (author)

167

TRANC - a novel fast-response converter to measure total reactive atmospheric nitrogen  

Science.gov (United States)

The input and loss of plant available nitrogen (reactive nitrogen: Nr) from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter), which offers the opportunity to quantify the sum of all airborne reactive nitrogen compounds (?Nr) in high time resolution. The basic concept of the TRANC is the full conversion of all Nr to nitrogen monoxide (NO) within two reaction steps. Initially, reduced Nr compounds are being oxidised, and oxidised Nr compounds are thermally converted to lower oxidation states. Particulate Nr is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher nitrogen oxides or those generated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD) for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3-, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in ?Nr concentrations and also matches the sum of all individual Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic conversions to NO occur. This assures a short residence time of the sample air inside the instrument, and minimises wall sorption problems of water soluble compounds. The fast response time (e-folding times of 0.30 to 0.35 s were found during concentration step changes) and high accuracy in capturing the dominant Nr species enables the converter to be used in an eddy covariance setup. Although a source attribution of specific Nr compounds is not possible, the TRANC is a new reliable tool for permanent measurements of the net ?Nr flux between ecosystem and atmosphere at a relatively low maintenance and reasonable cost level allowing for diurnal, seasonal and annual investigations.

Marx, O.; Brümmer, C.; Ammann, C.; Wolff, V.; Freibauer, A.

2012-05-01

168

TRANC – a novel fast-response converter to measure total reactive atmospheric nitrogen  

Directory of Open Access Journals (Sweden)

Full Text Available The input and loss of plant available nitrogen (reactive nitrogen: Nr from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter, which offers the opportunity to quantify the sum of all airborne reactive nitrogen compounds (?Nr in high time resolution. The basic concept of the TRANC is the full conversion of all Nr to nitrogen monoxide (NO within two reaction steps. Initially, reduced Nr compounds are being oxidised, and oxidised Nr compounds are thermally converted to lower oxidation states. Particulate Nr is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher nitrogen oxides or those generated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3?, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in ?Nr concentrations and also matches the sum of all individual Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic conversions to NO occur. This assures a short residence time of the sample air inside the instrument, and minimises wall sorption problems of water soluble compounds. The fast response time (e-folding times of 0.30 to 0.35 s were found during concentration step changes and high accuracy in capturing the dominant Nr species enables the converter to be used in an eddy covariance setup. Although a source attribution of specific Nr compounds is not possible, the TRANC is a new reliable tool for permanent measurements of the net ?Nr flux between ecosystem and atmosphere at a relatively low maintenance and reasonable cost level allowing for diurnal, seasonal and annual investigations.

V. Wolff

2012-05-01

169

FAST Mast Structural Response to Axial Loading: Modeling and Verification  

Science.gov (United States)

The International Space Station s solar array wing mast shadowing problem is the focus of this paper. A building-block approach to modeling and analysis is pursued for the primary structural components of the solar array wing mast structure. Starting with an ANSYS (Registered Trademark) finite element model, a verified MSC.Nastran (Trademark) model is established for a single longeron. This finite element model translation requires the conversion of several modeling and analysis features for the two structural analysis tools to produce comparable results for the single-longeron configuration. The model is then reconciled using test data. The resulting MSC.Nastran (Trademark) model is then extended to a single-bay configuration and verified using single-bay test data. Conversion of the MSC. Nastran (Trademark) single-bay model to Abaqus (Trademark) is also performed to simulate the elastic-plastic longeron buckling response of the single bay prior to folding.

Knight, Norman F., Jr.; Elliott, Kenny B.; Templeton, Justin D.; Song, Kyongchan; Rayburn, Jeffery T.

2012-01-01

170

Formulation and optimization of fast dissolving intraoral drug delivery system for clobazam using response surface methodology  

Science.gov (United States)

Clobazam is a newer 1,5-benzodiazepine used for the treatment of epilepsy. It is better tolerated and less sedating than other benzodiazepines. Absorption of the drug can be impacted by oral fast dissolving dosage form; this may have implications for epilepsy in pediatrics and those having difficulty in swallowing tablets/capsules resulting in improved patient compliance. The purpose of the present investigation was to formulate and optimize clobazam oro-dissolving tablets by direct compression method using response surface methodology (RSM). Oro-dispersible tablets of clobazam were prepared by direct compression method using crospovidone (2-6%) as a superdisintegrant, microcrystalline cellulose (MCC) (20-40%) was used as diluents along with directly compressible mannitol to enhance mouth feel. A 32 full factorial design was applied to investigate the combined effect of two formulation variables: amount of crospovidone and MCC over the independent variables disintegration time, wetting time and percent drug release. Disintegration time showed by all formulations was found to be in the range of 24.3-193 s based on evaluation parameters the formulation containing 6% of crospovidone and 30% of MCC showed promising performance against all other formulations. The results demonstrated that the RSM could efficiently be applied for the formulation of clobazam oro-dispersible tablets; therefore, constitute an advance in the management of epileptic attacks. PMID:24083203

Bala, Rajni; Khanna, Sushil; Pawar, Pravin K.

2013-01-01

171

Fast Response Systems Using Feed Forward Loop for Fuzzy Tuned PID Controllers  

Directory of Open Access Journals (Sweden)

Full Text Available The temperature during heating processes more essential in oil quantity .Many of the research effort they developed new control technique to control and regulate the steam temperature in industries. This seems to be because PID controllers is simple structure, assure acceptable performances for a wide range of industrial plants and their usage (the tuning of their parameters is well known among industrial operators. PID with FLC with combination of this we neglected the steady sate errors. PID controllers are particularly suited for pure first- or second-order processes, while industrial plants often present characteristics such as high order, time delays, nonlinearities and so on challenges during design the PID is to tune the PID parameters gain that suite to the plant. To overcome this problem, feed forward tuning PID using the fuzzy logic controller with self-tuning method is utilized to regulate the steam temperature. It gives good process dynamic characteristic which are process rise time, process settling time, percent overshoot and less steady state error. The ability to track any parameters changes and has fast recovery the output response during disturbance period.

M.Tharangini

2014-08-01

172

Fast Time and Space Parallel Algorithms for Solution of Parabolic Partial Differential Equations  

Science.gov (United States)

In this paper, fast time- and Space -Parallel agorithms for solution of linear parabolic PDEs are developed. It is shown that the seemingly strictly serial iterations of the time-stepping procedure for solution of the problem can be completed decoupled.

Fijany, Amir

1993-01-01

173

Count-to-count time interval distribution analysis in a fast reactor  

International Nuclear Information System (INIS)

The most important kinetic parameters have been measured at the zero power fast reactor CORAL-I by means of the reactor noise analysis in the time domain, using measurements of the count-to-count time intervals. (Author) 69 refs

174

Analysis of White Noise Limits for Stochastic Systems with Two Fast Relaxation Times  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper we present a rigorous asymptotic analysis for stochastic systems with two fast relaxation times. The mathematical model analyzed in this paper consists of a Langevin equation for the particle motion with time-dependent force constructed through an infinite dimensional Gaussian noise process. We study the limit as the particle relaxation time as well as the correlation time of the noise tend to zero and we obtain the limiting equations under appropriate assumpti...

Pavliotis, G. A.; Stuart, A. M.

2005-01-01

175

Fast retransmission of real-time traffic in HIPERLAN/2 systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Automatic repeat request (ARQ) schemes are effective to recover non-real-time data corrupted by channel errors, but their use with real-time traffic is seldom considered because packet retransmissions tend to increase the delay beyond the deadline. However, the high-speed of modern wireless local area networks, together with their inherent low propagation times, favors the use of ARQ schemes with real-time traffic. This paper proposes a fast retransmission scheduling mechanism for reliable tr...

Afonso, Jose? A.; Neves, Joaquim E.

2005-01-01

176

Flexible palladium-based H2 sensor with fast response and low leakage detection by nanoimprint lithography.  

Science.gov (United States)

Flexible palladium-based H2 sensors have a great potential in advanced sensing applications, as they offer advantages such as light weight, space conservation, and mechanical durability. Despite these advantages, the paucity of such sensors is due to the fact that they are difficult to fabricate while maintaining excellent sensing performance. Here, we demonstrate, using direct nanoimprint lithography of palladium, the fabrication of a flexible, durable, and fast responsive H2 sensor that is capable of detecting H2 gas concentration as low as 50 ppm. High resolution and high throughput patterning of palladium gratings over a 2 cm × 1 cm area on a rigid substrate was achieved by heat-treating nanoimprinted palladium benzyl mercaptide at 250 °C for 1 h. The flexible and robust H2 sensing device was fabricated by subsequent transfer nanoimprinting of these gratings into a polycarbonate film at its glass transition temperature. This technique produces flexible H2 sensors with improved durability, sensitivity, and response time in comparison to palladium thin films. At ambient pressure and temperature, the device showed a fast response time of 18 s at a H2 concentration of 3500 ppm. At 50 ppm concentration, the response time was found to be 57 s. The flexibility of the sensor does not appear to compromise its performance. PMID:23819468

Lim, Su Hui; Radha, Boya; Chan, Jie Yong; Saifullah, Mohammad S M; Kulkarni, Giridhar U; Ho, Ghim Wei

2013-08-14

177

NRESP-3, Organic Scintillation Detector Response to Monoenergetic Fast Neutron  

International Nuclear Information System (INIS)

1 - Description of problem or function: The programs calculate response functions of an organic scintillation detector for incident neutrons in the energy range from 0.05 to 20.0 MeV. The detector system consists of a cylindrical scintillator (e.g. NE213) surrounded by a cylindrical aluminium housing and connected to a lucite light pipe. 2 - Method of solution: The codes use the Monte Carlo method. Histories of neutrons emitted from a source positioned outside the scintillator are calculated. The spectrum of the light output from secondary charged particles produced by neutron reactions within the scintillator is calculated. 3 - Restrictions on the complexity of the problem: A neutron point source positioned at the scintillator axis at any distance from the scintillator or for larger distances with an angle from 0 to 90 degrees off this axis are considered. Cross section data for H, C, and Al up to 20 MeV are taken from ENDF/B-V. Non isotropic angular distributions are included for elastic and inelastic scattering from Al. Point cross sections are used with interpolation intervals of 20 to 100 keV. Wall effects are considered only for protons

178

Hormonal responses to extreme fasting in subantarctic fur seal (Arctocephalus tropicalis) pups.  

Science.gov (United States)

Surviving prolonged fasting implies closely regulated alterations in fuel provisioning to meet metabolic requirements, while preserving homeostasis. Little is known, however, of the endocrine regulations governing such metabolic adaptations in naturally fasting free-ranging animals. The hormonal responses to natural prolonged fasting and how they correlate to the metabolic adaptations observed, were investigated in subantarctic fur seal (Arctocephalus tropicalis) pups, which, because of the intermittent pattern of maternal attendance, repeatedly endure exceptionally long fasting episodes throughout their development (1-3 mo). Phase I fasting was characterized by a dramatic decrease in plasma insulin, glucagon, leptin, and total l-thyroxine (T(4)) associated with reductions in mass-specific resting metabolic rate (RMR), plasma triglycerides, glycerol, and urea-to-creatine ratio, while nonesterified fatty acids (NEFA) and ?-OHB increased. In contrast, the metabolic steady-state of phase II fasting reached within 6 days was associated with minimal concentrations of insulin, glucagon, and leptin; unchanged cortisol and triiodothyronine (T(3)); and moderately increased T(4). The early fall in insulin and leptin may mediate the shift to the strategy of energy conservation, protein sparing, and primary reliance on body lipids observed in response to the cessation of feeding. In contrast to the typical mammalian starvation response, nonelevated cortisol and minimal glucagon levels may contribute to body protein preservation and downregulation of catabolic pathways, in general. Furthermore, thyroid hormones may be involved in a process of energy conservation, independent of pups' nutritional state. These original hormonal settings might reflect an adaptation to the otariid repeated fasting pattern and emphasize the crucial importance of a tight physiological control over metabolism to survive extreme energetic constraints. PMID:22319050

Verrier, Delphine; Atkinson, Shannon; Guinet, Christophe; Groscolas, René; Arnould, John P Y

2012-04-15

179

Measurement of the dynamic response of differential pressure transmitters using a response time tester  

International Nuclear Information System (INIS)

alues using a long-life, fast acting 3-way solenoid valve. The actual pressure applied to the transmitter is measured with a high-frequency reference transducer. Once the operator has connected the air supply and transmitter, and set the test pressures, the actual testing and analysis proceeds automatically. Four sets of tests are conducted. A number of comparisons, as required by ISA-S67.06, are made to verify that: the transmitter is linear with respect to direction and rate of change; and the results are consistent between two diverse test methods. The broadband noise tests are used to find the transfer function (all the significant time constants) of the transmitter. Given the transfer function, the expected response to a step input can be computed and compared to the measured step response, thus verifying both measurements. The results are summarized and printed on the built-in printer. Files are saved to disk for later review. (author)

180

Analysis of time behavior of fast and intermediate neutrons in LINAC-TOF experiments  

International Nuclear Information System (INIS)

Time behavior of fast and intermediate neutrons in a graphite assembly is analyzed. Mean emission time of neutrons is calculated by the diffusion theory assuming the separability of space and time. And also space and angular dependent mean emission time of neutrons is analyzed by one-dimensional SN code ''ORISN''. Interesting results are obtained for the dependence of mean emission time on energy, space, pulse width of neutron source etc. on comparing the two results. There is a special feature in SN code ''ORISN'' in which the first trial input data of neutron flux for iterations is not required. Time dependent neutron spectrum is obtained with time dependent SN code ''T-ORISN'' developed by authors. Employed nuclear data is JAERI-FAST set and ABBN set. (author)

 
 
 
 
181

Development of a fast response dispersion model for virtual urban environments  

Science.gov (United States)

According to a UN report, more than 50% of the total world's population resides in urban areas and this fraction is increasing. Urbanization has a wide range of potential environmental impacts, including those related to the dispersion of potentially dangerous substances emitted from activities such as combustion, industrial processing or from deliberate harmful releases. This research is primarily focused on the investigation of various factors which contribute to the dispersion of certain classes of materials in a complex urban environment and improving both of the fundamental components of a fast response dispersion modeling system---wind modeling and dispersion modeling. Specifically, new empirical parameterizations have been suggested for an existing fast response wind model for street canyon flow fields. These new parameterizations are shown to produce more favorable results when compared with the experimental data. It is also demonstrated that the use of Graphics Processing Unit (GPU) technology can enhance the efficiency of an urban Lagrangian dispersion model and can achieve near real-time particle advection. The GPU also enables real-time visualizations which can be used for creating virtual urban environments to aid emergency responders. The dispersion model based on the GPU architecture relies on the so-called "simplified Langevin equations (SLEs)" for particle advection. The full or generalized form of the Langevin equations (GLEs) is known for its stiffness which tends to generate unstable modes in particle trajectory, where a particle may travel significant distances in a small time step. A fractional step methodology has been used to implement the GLEs into an existing Lagrangian random walk model to partially circumvent the stiffness associated with the GLEs. Dispersion estimates from the GLEs-based model have been compared with the SLEs-based model and available wind tunnel data. The GLEs-based model is more dispersive than the SLEs-based model in both the lateral and vertical directions. It is observed that for the present test case, the GLEs-based model performed relatively better than the SLEs-based model.

Singh, Balwinder

182

IRT Parameter Estimation with Response Times as Collateral Information  

Science.gov (United States)

Hierarchical modeling of responses and response times on test items facilitates the use of response times as collateral information in the estimation of the response parameters. In addition to the regular information in the response data, two sources of collateral information are identified: (a) the joint information in the responses and the…

van der Linden, Wim J.; Klein Entink, Rinke H.; Fox, Jean-Paul

2010-01-01

183

Design of a fast response ZrCo bed  

Energy Technology Data Exchange (ETDEWEB)

For the ITER SDS bed, several ZrCo beds have been developed. Required performance of the ITER SDS bed is rapid recovery, rapid delivery of tritium and accurate measurement of the amount of in-bed tritium. From the ZrCo bed developed by T. Hayashi, 90% of hydrogen was supplied in 60 min at 350 .deg. C and the amount of tritium was measured at {+-}1% accuracy within 24 hours. M. Glugla reported that 90% of hydrogen was delivered in 17 min at 400 .deg. C, but 30% of the recovery and delivery capacity was lost after 10 times of a hydriding/dehydriding by disproportionation of ZrCo hydride at high temperature at 400 .deg. C. Based on the study of two existing ZrCo beds, a new ZrCo bed was designed and fabricated in order to increase the delivery rate and minimize the disproportionation rate. In this study, a more improved ZrCo bed design is presented.

Shim, Myunghwa; Chung, Hongsuk; Jin, Haksoo; Lee, Jongkuk [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Yoshida, Hiroshi [Fusion Science Consultant, Ibakaki (Japan); Cho, Seungyon [National Fusion Research Institute, Daejeon (Korea, Republic of); Song, Kyumin [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

2008-10-15

184

The passive response of the Integral Fast Reactor concept to the chilled inlet accident  

Energy Technology Data Exchange (ETDEWEB)

Simple methods are described for bounding the passive response of a metal fueled liquid-metal cooled reactor to the chilled inlet accident. Calculation of these bounds for a prototype of the Integral Fast Reactor concept shows that failure limits --- eutectic melting, sodium boiling and fuel pin failure --- are not exceeded. 2 refs., 1 fig., 2 tabs.

Vilim, R.B.

1990-01-01

185

The passive response of the Integral Fast Reactor concept to the chilled inlet accident  

International Nuclear Information System (INIS)

Simple methods are described for bounding the passive response of a metal fueled liquid-metal cooled reactor to the chilled inlet accident. Calculation of these bounds for a prototype of the Integral Fast Reactor concept shows that failure limits --- eutectic melting, sodium boiling and fuel pin failure --- are not exceeded. 2 refs., 1 fig., 2 tabs

186

Sources of uncertainty in eddy covariance ozone flux measurements made by dry chemiluminescence fast response analysers  

Directory of Open Access Journals (Sweden)

Full Text Available We present a systematic intercomparison study of eddy covariance ozone flux measurements made using two fast response dry chemiluminescence analysers. Ozone deposition was measured over a well characterised managed grassland near Edinburgh, Scotland, during August 2007. A data quality control procedure specific to these analysers is introduced. Absolute ozone fluxes were calculated based on the relative signals of the dry chemiluminescence analysers using three different methods and the results are compared for both analysers. It is shown that the error in the fitted analyser calibration parameters required for the flux calculations provides a substantial source of uncertainty in the fluxes. The choice of the calculation method itself can also constitute an uncertainty in the flux as the calculated fluxes by the three methods do not agree within error at all times. This finding highlights the need for a consistent and rigorous approach for comparable datasets, such as e.g. in flux networks. Ozone fluxes calculated by one of the methods were then used to compare the two analysers in more detail. This systematic analyser comparison reveals half-hourly flux values differing by up to a factor of two at times with the difference in mean hourly flux ranging from 0 to 23% with an error in the mean daily flux of ± 12%. The comparison of analysers shows that the agreement in fluxes is excellent for some days but that there is an underlying uncertainty as a result of variable analyser performance and/or non-linear sensitivity.

J. B. A. Muller

2010-02-01

187

Dynamic Response of a fast near infra-red Mueller matrix ellipsometer  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The dynamic response of a near infrared Ferroelectric Liquid Crystal based Mueller matrix ellipsometer (NIR FLC-MME) is presented. A time dependent simulation model, using the measured time response of the individual FLCs, is used to describe the measured temporal response. Furthermore, the impulse response of the detector and the pre-amplifier is characterized and included in the simulation model. The measured time-dependent intensity response of the MME is reproduced in si...

Aas, Lars Martin Sandvik; Ellingsen, Pa?l Gunnar; Kildemo, Morten; Lindgren, Mikael

2010-01-01

188

Aroclor 1254 exposure reduces disease resistance and innate immune responses in fasted arctic charr  

Science.gov (United States)

To examine the immunological impacts of polychlorinated biphenyls (PCBs) in an environmentally relevant way, we orally contaminated Arctic charr (Salvelinus alpinus) with Aroclor 1254. After contamination, fish were either fed (0 and 100 mg Aroclor 1254 kg-1 fish wt) or fasted (0, 1, 10, and 100 mg kg-1) to mimic cycles of feeding-fasting experienced by Arctic animals. After four months, PCB concentrations in muscle were the same in fasted and fed fish; however, PCBs in kidneys of fed fish were 33 to 50% of those in fasted fish. Arctic charr were exposed to Aeromonas salmonicida, the bacteria responsible for furunculosis, by cohabitation with infected conspecifics. Fasted fish had a significant trend toward lower survival with higher dose of PCBs - from 68% in controls to 48% in treatment involving 100 mg kg-1. Independent of PCB contamination, fed fish had the lowest survival; we attribute this to stress associated with establishing and maintaining feeding hierarchies. A significant decrease in the activity of lysozyme was observed in skin mucus, as was hemagglutination ability of a putative rhamnose lectin in fasted, but not in fed, PCB-treated fish. These results demonstrate the immunosuppressive effects of PCBs on Arctic charr, and they illustrate the importance of considering environmentally relevant nutritional status in ecotoxicological studies.

Maule, A.G.; Jorgensen, E.H.; Vijayan, M.M.; Killie, J.-E.A.

2005-01-01

189

Physiological responses of juvenile rainbow trout to fasting and swimming activity: Effects on body composition and condition indices  

Science.gov (United States)

The physiological traits that allow fish to survive periods of limited food resources are poorly understood. We assessed changes in proximate body composition, relative organ mass, blood metabolites, and relative weight (Wr) of sedentary and actively swimming (15 cm/s) juvenile rainbow trout (154-182 mm total length) over 147 d of fasting. Fasting caused measurable responses that were augmented when fish were swimming. Lipids and plasma triacylglycerides declined over time. Proteins were catabolized simultaneously with lipid reserves, but ammonia concentrations in plasma did not increase. The liver somatic index (LSI) did not change substantially over 105 d, suggesting that gluconeogenesis maintained blood glucose concentrations and hepatic glycogen reserves for a substantial period of fasting. The gut somatic index (GSI) and Wr declined linearly during fasting, but the LSI did not decline until after 105 d of fasting. Consequently, the use of different body condition indices could lead to different conclusions about the condition of juvenile rainbow trout. Swimming activity caused fish to have lower lipid and protein reserves than those of sedentary fish. No mortalities were observed among sedentary fish, but mortalities occurred among actively swimming fish after 97 d of fasting when 3.2% or less lipid remained in their bodies. Body condition indices did not account for differences in proximate body composition between sedentary and actively swimming fish and were relatively poor predictors of lipid content and risk of mortality. The probability of mortality was most accurately predicted by percent lipid content. Therefore, we suggest that fisheries scientists consider using percent lipid content when evaluating the physiological status and risk of mortality due to starvation among juvenile rainbow trout.

Simpkins, D. G.; Hubert, W. A.; Del, Rio, C. M.; Rule, D. C.

2003-01-01

190

Structural brain variation, age, and response time.  

Science.gov (United States)

Response time (RT) generally slows with aging, but the contribution of structural brain changes to this slowing is unknown. We used voxel-based morphometry (VBM) to determine gray matter (GM) and white matter (WM) brain volumes in 9 middle-aged adults (38-58 years old) and 9 seniors (66-82 years old). We correlated brain volumes with RT assessed in both a simple visual stimulus-response task and a visual continuous recognition memory task. No GM correlations with simple RT were significant; there was one WM correlation in the right fusiform gyrus. In the memory task, faster RT was correlated (p < .05, corrected) with less GM in the globus pallidus, the parahippocampus, and the thalamus for both groups. Several Brodmann areas (BA) differed between the groups such that in each area, less GM was correlated with slower RTs in the middle-aged group but with faster RTs in the senior group (BAs 19, 37, 46, 9, 8, 6, 13, 10, 41, and 7). The results suggest that individual differences in specific brain structure volumes should be considered as potential moderating factors in cognitive brain imaging studies. PMID:16180630

Haier, Richard J; Jung, Rex E; Yeo, Ronald A; Head, Kevin; Alkire, Michael T

2005-06-01

191

Fast computation of finite-time Lyapunov exponent fields for unsteady flows  

Science.gov (United States)

This paper presents new efficient methods for computing finite-time Lyapunov exponent (FTLE) fields in unsteady flows. The methods approximate the particle flow map, eliminating redundant particle integrations in neighboring flow map calculations. Two classes of flow map approximations are investigated based on composition of intermediate flow maps; unidirectional approximation constructs a time-T map by composing a number of smaller time-h maps, while bidirectional approximation constructs a flow map by composing both positive- and negative-time maps. The unidirectional method is shown to be fast and accurate, although it is memory intensive. The bidirectional method is also fast and uses significantly less memory; however, it is prone to error which is large in regions where the opposite-time FTLE field is large, rendering it unusable. The algorithms are implemented and compared on three example fluid flows: a double gyre, a low Reynolds number pitching flat plate, and an unsteady ABC flow.

Brunton, Steven L.; Rowley, Clarence W.

2010-03-01

192

Enhanced response of the regular networks to local signals in presence of a fast impurity  

CERN Document Server

We consider an array of inductively coupled Josephson junctions with a fast impurity (a junction with a smaller value of critical current), and study the consequences of imposing a small amplitude periodic signal at some point in the array. We find that when external signal is imposed at the impurity, the response of the array is boosted and a small amplitude signal can be detected throughout the array. When the signal is imposed elsewhere, minor effects is seen on the dynamics of the array. The same results have been also seen in presence of a single fast spiking neuron in a chain of diffusively coupled FitzHugh-Nagumo neurons.

Valizadeh, Alireza

2012-01-01

193

Fast structural responses of gap junction membrane domains to AB5 toxins  

Science.gov (United States)

Gap junctions (GJs) represent connexin-rich membrane domains that connect interiors of adjoining cells in mammalian tissues. How fast GJs can respond to bacterial pathogens has not been known previously. Using Bessel beam plane illumination and confocal spinning disk microscopy, we found fast (?500 ms) formation of connexin-depleted regions (CDRs) inside GJ plaques between cells exposed to AB5 toxins. CDR formation appears as a fast redistribution of connexin channels within GJ plaques with minor changes in outline or geometry. CDR formation does not depend on membrane trafficking or submembrane cytoskeleton and has no effect on GJ conductance. However, CDR responses depend on membrane lipids, can be modified by cholesterol-clustering agents and extracellular K+ ion concentration, and influence cAMP signaling. The CDR response of GJ plaques to bacterial toxins is a phenomenon observed for all tested connexin isoforms. Through signaling, the CDR response may enable cells to sense exposure to AB5 toxins. CDR formation may reflect lipid-phase separation events in the biological membrane of the GJ plaque, leading to increased connexin packing and lipid reorganization. Our data demonstrate very fast dynamics (in the millisecond-to-second range) within GJ plaques, which previously were considered to be relatively stable, long-lived structures. PMID:24133139

Majoul, Irina V.; Gao, Liang; Betzig, Eric; Onichtchouk, Daria; Butkevich, Eugenia; Kozlov, Yuri; Bukauskas, Feliksas; Bennett, Michael V. L.; Lippincott-Schwartz, Jennifer; Duden, Rainer

2013-01-01

194

Fast response measurements of the dispersion of nanoparticles in a vehicle wake and a street canyon  

Science.gov (United States)

The distributions of nanoparticles (below 300 nm in diameter) change rapidly after emission from the tail pipe of a moving vehicle due to the influence of transformation processes. Information on this time scale is important for modelling of nanoparticle dispersion but is unknown because the sampling frequencies of available instruments are unable to capture these rapid processes. In this study, a fast response differential mobility spectrometer (Cambustion Instruments DMS500), originally designed to measure particle number distributions (PNDs) and concentrations in engine exhaust emissions, was deployed to measure particles in the 5-1000 nm size range at a sampling frequency of 10 Hz. This article presents results of two separate studies; one, measurements along the roadside in a Cambridge (UK) street canyon and, two, measurements at a fixed position (20 cm above road level), centrally, in the wake of a single moving diesel-engined car. The aims of the first measurements were to test the suitability and recommend optimum operating conditions of the DMS500 for ambient measurements. The aim of the second study was to investigate the time scale over which competing influences of dilution and transformation processes (nucleation, condensation and coagulation) affect the PNDs in the wake of a moving car. Results suggested that the effect of transformation processes was nearly complete within about 1 s after emission due to rapid dilution in the vehicle wake. Furthermore, roadside measurements in a street canyon showed that the time for traffic emissions to reach the roadside in calm wind conditions was about 45 ± 6 s. These observations suggest the hypothesis that the effects of transformation processes are generally complete by the time particles are observed at roadside and the total particle numbers can then be assumed as conserved. A corollary of this hypothesis is that complex transformation processes can be ignored when modelling the behaviour of nanoparticles in street canyons once the very near-exhaust processes are complete.

Kumar, Prashant; Robins, Alan; Britter, Rex

2009-12-01

195

Measurement of fast assembly spectra using time-of-flight method  

International Nuclear Information System (INIS)

Measurement of neutron spectra made in fast subcritical assemblies HUG 3 and PHUG 3 (uranium-graphite and plutonium-graphite) utilizing time-of-flight techniques are described. The matrix were excited by the pulsed neutron source from the BCMN Linac beam impinging on a target of natural uranium. Details of the experimental procedure, safety studies, detector calibration and data reduction are given

196

Time domain response of electrical ceramics -- Micro to megaseconds  

Energy Technology Data Exchange (ETDEWEB)

The electrical properties of ceramics can be measured in either the time domain or in the frequency domain. But for electrically nonlinear ceramics such as varistors, time-domain measurements provide insights that are different and more relevant to material performance as well as being more physically incisive. This article focuses specifically on the electrical properties of ZnO varistors, but much of it is of relevance for other materials, in particular those materials with grain-boundary barriers and disordered ceramics or glasses. The interpretation of electrical measurements in the time domain is profoundly influenced by such practical matters as source impedance and waveform characteristics. Experimental results are presented for both high and low source impedance relative to that of a test varistor, and the different in experimental difficulty and ease of interpretation is described. Time-domain measurements of capacitance and of the inductive response of varistors to large, fast electrical pulses are presented and their implications for varistor theory are given. Experimental evidence is given of short- and long-term memory in varistors. These memory phenomena are ascribed respectively to the life time of holes that become trapped in barriers and to polarization currents originating from deep electron traps. Polarization current measurements are presented for a wide range of time and temperature. The power-law time dependence and universal behavior of these currents is discussed. The exponent that describes the power law behavior is seen to change with temperature, and the change is interpreted as a double transition from diffusive to dispersive transport that originates with current from two different electron traps.

Modine, F.A. [Oak Ridge National Lab., TN (United States). Solid State Div.

1997-11-01

197

Fast MCMC sampling for Markov jump processes and continuous time Bayesian networks  

CERN Document Server

Markov jump processes and continuous time Bayesian networks are important classes of continuous time dynamical systems. In this paper, we tackle the problem of inferring unobserved paths in these models by introducing a fast auxiliary variable Gibbs sampler. Our approach is based on the idea of uniformization, and sets up a Markov chain over paths by sampling a finite set of virtual jump times and then running a standard hidden Markov model forward filtering-backward sampling algorithm over states at the set of extant and virtual jump times. We demonstrate significant computational benefits over a state-of-the-art Gibbs sampler on a number of continuous time Bayesian networks.

Rao, Vinayak

2012-01-01

198

MONTE CARLO CALCULATION OF THE ENERGY RESPONSE OF THE NARF HURST-TYPE FAST- NEUTRON DOSIMETER  

Energy Technology Data Exchange (ETDEWEB)

The response function for the fast-neutron dosimeter was calculated by the Monte Carlo technique (Code K-52) and compared with a calculation based on the Bragg-Gray principle. The energy deposition spectra so obtained show that the response spectra become softer with increased incident neutron energy ahove 3 Mev. The K-52 calculated total res nu onse is more nearly constant with energy than the BraggGray response. The former increases 70 percent from 1 Mev to 14 Mev while the latter increases 135 percent over this energy range. (auth)

De Vries, T.W.

1963-06-15

199

Study of neutronic perturbation using complementary variational principle in a fast reactor with matrix response technique  

International Nuclear Information System (INIS)

In the study of the fast reactor safety, we have looked for a perturbation in the reactor core, by the response matrix technique. As theoretical support, we have used the second order variational principle for the determination of the response matrix elements. We have added a contraint which consists to the respect of the neutronic balance. For the needs of this principle, we have built a trial function basis composed of space and angle harmonic polynomials. We have also computed the bounds of the response matrix elements, using the ACKROYD's complementary variational principle. The mean of the bounds lead to acceptable results. Numerical tests have been conducted to evaluate the mathematical model accuracy

200

A fast-running multi-dimensional space-time kinetic code for pressurized water reactors  

International Nuclear Information System (INIS)

An accurate and fast-running multi-dimensional space-time kinetic code has been developed in this thesis. The FACT code, an acronym of fast-running analysis code for core transients, was developed based on the Core-Wise Green's Function methodology, which is a very fast nodal method with good accuracy. The Stiffness Confinement Method was also adopted, and a so-called dynamic frequency function was introduced to minimize the time discretization error. Through more accurate representation of the flux and the dynamic frequency function in a time interval, the proposed scheme allows the use of a much larger time step size compared to the conventional method of applying the finite difference technique to the time derivative. The accuracy and efficiency of the resultant numerical scheme were tested for benchmark problems with and without thermal-hydraulic feedback effects. The proposed formulation has been demonstrated to provide accurate results with very small time discretization errors for the problems investigated, allowing much larger time step sizes to be used without losing the accuracy

 
 
 
 
201

A novel fast gas chromatography method for higher time resolution measurements of speciated monoterpenes in air  

Science.gov (United States)

Biogenic emissions supply the largest fraction of non-methane volatile organic compounds (VOC) from the biosphere to the atmospheric boundary layer, and typically comprise a complex mixture of reactive terpenes. Due to this chemical complexity, achieving comprehensive measurements of biogenic VOC (BVOC) in air within a satisfactory time resolution is analytically challenging. To address this, we have developed a novel, fully automated Fast Gas Chromatography (Fast-GC) based technique to provide higher time resolution monitoring of monoterpenes (and selected other C9-C15 terpenes) during plant emission studies and in ambient air. To our knowledge, this is the first study to apply a Fast-GC based separation technique to achieve quantification of terpenes in ambient air. Three chromatography methods have been developed for atmospheric terpene analysis under different sampling scenarios. Each method facilitates chromatographic separation of selected BVOC within a significantly reduced analysis time compared to conventional GC methods, whilst maintaining the ability to quantify individual monoterpene structural isomers. Using this approach, the C9-C15 BVOC composition of single plant emissions may be characterised within a 14.5 min analysis time. Moreover, in-situ quantification of 12 monoterpenes in unpolluted ambient air may be achieved within an 11.7 min chromatographic separation time (increasing to 19.7 min when simultaneous quantification of multiple oxygenated C9-C10 terpenoids is required, and/or when concentrations of anthropogenic VOC are significant). These analysis times potentially allow for a twofold to fivefold increase in measurement frequency compared to conventional GC methods. Here we outline the technical details and analytical capability of this chromatographic approach, and present the first in-situ Fast-GC observations of 6 monoterpenes and the oxygenated BVOC (OBVOC) linalool in ambient air. During this field deployment within a suburban forest ~30 km west of central Tokyo, Japan, the Fast-GC limit of detection with respect to monoterpenes was 4-5 ppt, and the agreement between Fast-GC and PTR-MS derived total monoterpene mixing ratios was consistent with previous GC/PTR-MS comparisons. The measurement uncertainties associated with the Fast-GC quantification of monoterpenes are ? 12%, while larger uncertainties (up to ~25%) are associated with the OBVOC and sesquiterpene measurements.

Jones, C. E.; Kato, S.; Nakashima, Y.; Kajii, Y.

2014-05-01

202

Fast Mapping Across Time: Memory Processes Support Children's Retention of Learned Words  

Directory of Open Access Journals (Sweden)

Full Text Available Children's remarkable ability to map linguistic labels to objects in the world is referred to as fast mapping. The current study examined children's (N = 216 and adults’ (N = 54 retention of fast-mapped words over time (immediately, after a 1 week delay, and after a 1 month delay. The fast mapping literature often characterizes children's retention of words as consistently high across timescales. However, the current study demonstrates that learners forget word mappings at a rapid rate. Moreover, these patterns of forgetting parallel forgetting functions of domain general memory processes. Memory processes are critical to children's word learning and the role of one such process, forgetting, is discussed in detail—forgetting supports both word mapping and the generalization of words and categories.

HaleyVlach

2012-02-01

203

Studies on fast timing and high precision tracking performance of Resistive Plate Chamber  

CERN Document Server

Resistive plate chambers (RPC), produced in large scales, are widely used as trigger detectors with O(ns) time resolution in high energy and high intensity experiments. To confront the future high experimental frontiers, such as the super-LHC, RPCs equipped with fine-pitch readout strips were tested with 180GeV/c muon at CERN SPS H8 beam line, to assess the viability of using RPCs for both fast timing and high precision tracking trigger.

Han, L; The ATLAS collaboration

2013-01-01

204

The ''Flight Chamber'': A fast, large area, zero-time detector  

International Nuclear Information System (INIS)

A new, fast, zero-time detector with an active area of 20 cm2 has been constructed. Secondary electrons from a thin self-supporting foil are accelerated onto a scinitllator. The intrinsic time resolution (fwhm) was 0.85 for 5.5 MeV ?-particles and 0.42 ns for 17 MeV 16O-ions, at an efficiency of 97.5% and 99.6%, respectively. (author)

205

Note: A timing micro-channel plate detector with backside fast preamplifier  

Science.gov (United States)

A timing micro-channel plate detector with a backside double-channel fast preamplifier was developed to avoid distortion during signal propagation from the anode to the preamplifier. The mechanical and electronic structure is described. The detector including its backside preamplifier is tested by a 241Am ?-source and a rise time of ˜2 ns with an output background noise of 4 mVrms was achieved.

Wang, Wei; Yu, Deyang; Lu, Rongchun; Liu, Junliang; Cai, Xiaohong

2014-03-01

206

Note: A timing micro-channel plate detector with backside fast preamplifier  

Energy Technology Data Exchange (ETDEWEB)

A timing micro-channel plate detector with a backside double-channel fast preamplifier was developed to avoid distortion during signal propagation from the anode to the preamplifier. The mechanical and electronic structure is described. The detector including its backside preamplifier is tested by a {sup 241}Am ?-source and a rise time of ?2 ns with an output background noise of 4 mV{sub rms} was achieved.

Wang, Wei [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Yu, Deyang, E-mail: d.yu@impcas.ac.cn; Lu, Rongchun; Liu, Junliang; Cai, Xiaohong [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2014-03-15

207

A fast rise time high voltage pulse generator for bounded-wave EMP simulator  

International Nuclear Information System (INIS)

A high voltage pulse generator with fast rise time is developed. The output wave of this generator is presented. The electromagnetic environment with 1.2 ns or 2.8 ns rise time and 50 ns pulse width can be produced when this generator is connected to bounded-wave EMP simulator which is used to investigate the EMP coupling effects of electrical equipment. (authors)

208

The reality of the surgical fasting time in the era of the ERAS protocol.  

Science.gov (United States)

Multimodal protocols to optimize perioperative care and to accelerate postoperative recovery include abbreviated pre-and postoperative fasting. The aim of this study was to investigate the pre and postoperative fasting period and the factors that influence it in patients who underwent elective operations. We included patients who underwent surgery of the digestive tract and abdominal wall. Data were collected from the patients and from their personal health records. We included 135 patients between 19 and 89 years old. Most were adults (75.55%), female (60.74%) and the most common procedures were hernioplasty (42.96%) and cholecystectomy (34.81%). The preoperative fasting periods for solids and liquids were similar, median 16.50 (5.50-56.92) and 15.75 (2.50- 56.92) hours, respectively. The preoperative fasting period was influenced by the instruction received and surgery time. Postoperative fasting period was 15.67 (1.67-90.42) hours and was influenced by type of surgery and lack of synchrony between the clinical meeting and the nutrition and dietetics service schedules. PMID:24528365

Cestonaro, Talita; Madalozzo Schieferdecker, Maria Eliana; Thieme, Rubia Daniela; Neto Cardoso, João; Ligocki Campos, Antônio Carlos

2014-01-01

209

Response of six neutron survey meters in mixed fields of fast and thermal neutrons  

International Nuclear Information System (INIS)

Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the 241Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ?9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ?85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ?50 % in the thermal neutron field. (authors)

210

An efficient fast response and high-gain solar-blind flexible ultraviolet photodetector employing hybrid geometry  

Science.gov (United States)

We report high performance flexible hybrid ultraviolet photodetector with solar-blind sensitivity using nanocomposite film of plasma polymerized aniline-titanium dioxide. A facile solvent-free plasma technique is used to synthesize superior quality hybrid material with high yield. The hybrid photodetector exhibited high photoconductive gain of the order of ˜105 and fast speed with response and recovery time of 22.87 ms and 34.23 ms. This is an excellent result towards getting a balance in the response speed and photoconductive gain trade-off of the photodetectors reported so far. In addition, the device has the advantages of enhanced photosensitivity ((Ilight - Idark)/Idark) of the order of ˜102 and high responsivity of ˜104 AW-1. All the merits substantiates that, to prepare hybrid material, plasma based method holds potential to be an easy way for realizing large scale nanostructured photodetectors for practical applications.

Hussain, Amreen A.; Pal, Arup R.; Patil, Dinkar S.

2014-05-01

211

A fast response and large electrically tunable-focusing imaging system based on switching of two modes of a liquid crystal lens  

Science.gov (United States)

We demonstrated a fast response and large tunable focusing imaging system consisting of a lens module and a liquid crystal (LC) lens based on the switching of two modes of a LC lens: the negative LC lens and positive LC lens. By discarding the conventional operation of a positive LC lens only in the imaging system, large tunable focusing range can be achieve from 300 to 10 cm owning to the phase change between the positive and the negative LC lens; meanwhile, the response time is fast (˜433 ms). The potential applications are autofocused cell phones, and cameras.

Lin, Hung-Chun; Lin, Yi-Hsin

2010-08-01

212

Observation of very fast response signals from Pb absorber coupled transition edge sensor gamma-ray microcalorimeter  

International Nuclear Information System (INIS)

We are developing a gamma-ray microcalorimeter for Positron Annihilation Spectroscopy. Our detector composed of a transition edge sensor (TES) thermometer and an epoxy coupled bulk Pb absorber has been reported an energy resolution of 4.7 keV FWHM at 662 keV with a tens of milliseconds long response time. To enhance the detector properties, we designed a new attachment method in the focus of improving the thermal coupling between the absorber and the TES. In the new design, we created epoxy-posts both on the TES film and on the absorber, and then they were connected together using an epoxy-dot put on the epoxy-post on the absorber. Measured current signal of this epoxy-post TES gamma-ray detector showed an ultra fast response with 80 ?s fall time.

213

Fast time-reversible algorithms for molecular dynamics of rigid-body systems.  

Science.gov (United States)

In this paper, we present time-reversible simulation algorithms for rigid bodies in the quaternion representation. By advancing a time-reversible algorithm [Y. Kajima, M. Hiyama, S. Ogata, and T. Tamura, J. Phys. Soc. Jpn. 80, 114002 (2011)] that requires iterations in calculating the angular velocity at each time step, we propose two kinds of iteration-free fast time-reversible algorithms. They are easily implemented in codes. The codes are compared with that of existing algorithms through demonstrative simulation of a nanometer-sized water droplet to find their stability of the total energy and computation speeds. PMID:22779579

Kajima, Yasuhiro; Hiyama, Miyabi; Ogata, Shuji; Kobayashi, Ryo; Tamura, Tomoyuki

2012-06-21

214

High-purity CsI scintillators for fast timing applications  

International Nuclear Information System (INIS)

The basic requirements in fast coincidence measurements are good time resolution, high efficiency, and the highest possible count rate. The two latter requirements can be expressed by the statistical utility rate. These properties of BaF2 and pure CsI scintillators were compared from the viewpoint of positron lifetime spectroscopy. Time resolution, peak-to background ratio (ratio of the true and random coincidences) and statistical utility rate values were determined for fast coincidence systems with BaF2-BaF2 and BaF2-pure CsI scintillators. Although the time resolution was found to be worse, the peak to background ratio and the statistical utility rate were better for BaF2 -pure CsI scintillators thus indicating that pure CsI is competitive with BaF2

215

Interactions of fast and slow waves in problems with two time scales  

International Nuclear Information System (INIS)

Consideration is given to certain symmetric hyperbolic systems of nonlinear partial differential equations whose solutions vary on two time scales, a slow scale t and a fast scale t/epsilon. It is shown that if the initial data are not prepared correctly for the suppression of the fast scale motion and contain errors of amplitude O(epsilon to the mu), so that only mu time derivatives of the solution are bounded at t 0, then fast waves of amplitude O(epsilon to the mu) will be present in the solution. The error introduced in the slow scale motion by nonlinear interactions of these waves, however, will only be of amplitude O(epsilon to the 2 mu) + O(epsilon to the mu + 1). Since this holds for any mu greater than 0, it extends the results given by Kreiss (1979, 1980). It is concluded that the effects of the fast waves can be controlled more easily than has been thought. There is thus partial justification for neglecting them in certain physical situations. 19 references

216

A single phase voltage regulator module (VRM) with stepping inductance for fast transient response  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A single-phase fast transient converter topology with stepping inductance is proposed. The stepping inductance method is implemented by replacing the conventional inductor in a buck converter by two inductors connecting in series. One has large inductance and the other has small inductance. The inductor with small inductance will take over the output inductor during transient load change and speed up dynamic response. In steady state, the large inductance takes over and keeps a substantially ...

Lu, Ddc; Liu, Jcp; Poon, Fnk; Pong, Bmh

2007-01-01

217

Accurate measurement of the rise and decay times of fast scintillators with solid state photon counters  

International Nuclear Information System (INIS)

In this work we present a measurement setup for the determination of scintillation pulse shapes of fast scintillators. It is based on a time-correlated single photon counting approach that utilizes the correlation between 511 keV annihilation photons to produce start and stop signals in two separate crystals. The measurement is potentially cost-effective and simple to set up while maintaining an excellent system timing resolution of 125 ps. As a proof-of-concept the scintillation photon arrival time histograms were recorded for two well-known, fast scintillators: LYSO:Ce and LaBr3:5%Ce. The scintillation pulse shapes were modeled as a linear combination of exponentially distributed charge transfer and photon emission processes. Correcting for the system timing resolution, the exponential time constants were extracted from the recorded histograms. A decay time of 43 ns and a rise time of 72 ps were determined for LYSO:Ce thus demonstrating the capability of the system to accurately measure very fast rise times. In the case of LaBr3:5%Ce two processes were observed to contribute to the rising edge of the scintillation pulse. The faster component (270 ps) contributes with 72% to the rising edge of the scintillation pulse while the second, slower component (2.0 ns) contributes with 27%. The decay of the LaBr3:5%Ce scintillation pulse was measured to be 15.4 ns with a small contribution (2%) of a component with a larger time constant (130 nmponent with a larger time constant (130 ns).

218

Evaluation of nonlinear structural dynamic responses using a fast-running spring-mass formulation  

Energy Technology Data Exchange (ETDEWEB)

In today`s world, accurate finite-element simulations of large nonlinear systems may require meshes composed of hundreds of thousands of degrees of freedom. Even with today`s fast computers and the promise of ever-faster ones in the future, central processing unit (CPU) expenditures for such problems could be measured in days. Many contemporary engineering problems, such as those found in risk assessment, probabilistic structural analysis, and structural design optimization, cannot tolerate the cost or turnaround time for such CPU-intensive analyses, because these applications require a large number of cases to be run with different inputs. For many risk assessment applications, analysts would prefer running times to be measurable in minutes. There is therefore a need for approximation methods which can solve such problems far more efficiently than the very detailed methods and yet maintain an acceptable degree of accuracy. For this purpose, we have been working on two methods of approximation: neural networks and spring-mass models. This paper presents our work and results to date for spring-mass modeling and analysis, since we are further along in this area than in the neural network formulation. It describes the physical and numerical models contained in a code we developed called STRESS, which stands for ``Spring-mass Transient Response Evaluation for structural Systems``. The paper also presents results for a demonstration problem, and compares these with results obtained for the same problem using PRONTO3D, a state-of-the-art finite element code which was also developed at Sandia.

Benjamin, A.S.; Altman, B.S.; Gruda, J.D.

1995-03-01

219

Fast monitoring of epileptic seizures using recurrence time statistics of electroencephalography  

Directory of Open Access Journals (Sweden)

Full Text Available Epilepsy is one of the most common disorders of the brain. Currently, determination of epileptic seizures often involves tedious, time-consuming visual inspection of electroencephalography (EEG data by medical experts. To better monitor seizures and make medications more effective, we propose a recurrence time based approach to characterize brain electrical activity. Recurrence times have a number of distinguished properties that make it very effective for forwarning epileptic seizures as well as studying propagation of seizures: 1 recurrence times amount to periods of periodic signals, 2 recurrence times are closely related to information dimension, Lyapunov exponent, and Kolmogorov entropy of chaotic signals, 3 recurrence times embody Shannon and Renyi entropies of random fields, and 4 recurrence times can readily detect bifurcation-like transitions in dynamical systems. In particular, property 4 dictates that unlike many other nonlinear methods, recurrence time method does not require the EEG data be chaotic and/or stationary. Moreover, the method only contains a few parameters that are largely signal-independent, and hence, is very easy to use. The method is also very fast—it is fast enough to on-line process multi-channel EEG data with a typical PC. Therefore, it has the potential to be an excellent candidate for real-time monitoring of epileptic seizures in a clinical setting.

JianboGao

2013-10-01

220

Organic scintillators response function modeling for Monte Carlo simulation of Time-of-Flight measurements  

International Nuclear Information System (INIS)

In neutron Time-of-Flight (TOF) measurements performed with fast organic scintillation detectors, both pulse arrival time and amplitude are relevant. Monte Carlo simulation can be used to calculate the time–energy dependant neutron flux at the detector position. To convert the flux into a pulse height spectrum, one must calculate the detector response function for mono-energetic neutrons. MCNP can be used to design TOF systems, but standard MCNP versions cannot reliably calculate the energy deposited by fast neutrons in the detector since multiple scattering effects must be taken into account in an analog way, the individual recoil particles energy deposit being summed with the appropriate scintillation efficiency. In this paper, the energy response function of 2?×2? and 5?×5? liquid scintillation BC-501 A (Bicron) detectors to fast neutrons ranging from 20 keV to 5.0 MeV is computed with GEANT4 to be coupled with MCNPX through the “MCNP Output Data Analysis” software developed under ROOT (). - Highlights: ? GEANT4 has been used to model organic scintillators response to neutrons up to 5 MeV. ? The response of 2?×2? and 5?×5? BC501A detectors has been parameterized with simple functions. ? Parameterization will allow the modeling of neutron Time of Flight measurements with MCNP using tools based on CERN's ROOT.

 
 
 
 
221

TRANC – a novel fast-response converter to measure total reactive atmospheric nitrogen  

Directory of Open Access Journals (Sweden)

Full Text Available The input and loss of plant available nitrogen (N from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for the measurement of total reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter, which offers the opportunity to quantify the sum of all airborne reactive nitrogen (Nr compounds in high time resolution. The basic concept of the TRANC is the full conversion of total Nr to nitrogen monoxide (NO within two reaction steps. Initially, reduced N compounds are being oxidised, and oxidised N compounds are thermally converted to lower oxidation states. Particulate N is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher N oxides or those originated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3?, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in Nr concentrations and also matches the sum of all Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic conversions to NO occur. This assures a short residence time of the sample air inside the instrument, and minimises wall sorption problems of water soluble compounds. The fast response time (half-value periods of 0.30 s were found during concentration step changes and high accuracy in capturing the dominant Nr species enables the converter to be used in an eddy covariance setup. Although a source attribution of specific Nr compounds is not possible, the TRANC is a new reliable tool for permanent measurements of the net Nr flux between ecosystem and atmosphere at a relatively low maintenance and reasonable cost level allowing for diurnal, seasonal and annual investigations.

O. Marx

2011-12-01

222

Using a fast-gated camera for measurements of transverse beam distributions and damping times  

Energy Technology Data Exchange (ETDEWEB)

With a fast-gated camera, synchrotron light was used for studying the transverse beam distributions and damping times in the Stanford Linear Collider (SLC) damping rings. By digitizing the image in the camera signal, the turn-by-turn time evolution of the transverse beam distribution was monitored and analyzed. The projections of the digitized image were fit with Gaussian functions to determine the moments of the distribution. Practical applications include the determination of injection matching parameters and the transverse damping times. In this report we describe a synchrotron light monitor and present experimental data obtained in the SLC damping rings.

Minty, M.; Brown, R.; Decker, F.J.; Emma, P.; Krejcik, P.; Limberg, T.; McCormick, D.; Ross, M.; Siemann, R.; Spence, W.

1992-11-01

223

A novel insitu estimation of time constant for core temperature sensors in Fast Breeder Reactor  

International Nuclear Information System (INIS)

The temperature of sodium at the outlet nozzles of fuel sub-assemblies in a liquid metal cooled fast breeder reactor (LMFBR) is one of the most critical parameters to be monitored continuously for safe and reliable operation of the reactor. The installed time constant of the thermocouple is around 6 +/- 2 sec. This paper describes the method for determining the insitu time constant of the core monitoring thermocouples located inside thermowell using the bare central 2mm dia thermocouple of known time constant as reference. (author)

224

Using a fast-gated camera for measurements of transverse beam distributions and damping times  

International Nuclear Information System (INIS)

With a fast-gated camera, synchrotron light was used for studying the transverse beam distributions and damping times in the Stanford Linear Collider (SLC) damping rings. By digitizing the image in the camera signal, the turn-by-turn time evolution of the transverse beam distribution was monitored and analyzed. The projections of the digitized image were fit with Gaussian functions to determine the moments of the distribution. Practical applications include the determination of injection matching parameters and the transverse damping times. In this report we describe a synchrotron light monitor and present experimental data obtained in the SLC damping rings

225

Real-time, fast radio transient searches with GPU de-dispersion  

CERN Document Server

The identification, and subsequent discovery, of fast radio transients through blind-search surveys requires a large amount of processing power, in worst cases scaling as $\\mathcal{O}(N^3)$. For this reason, survey data are generally processed offline, using high-performance computing architectures or hardware-based designs. In recent years, graphics processing units have been extensively used for numerical analysis and scientific simulations, especially after the introduction of new high-level application programming interfaces. Here we show how GPUs can be used for fast transient discovery in real-time. We present a solution to the problem of de-dispersion, providing performance comparisons with a typical computing machine and traditional pulsar processing software. We describe the architecture of a real-time, GPU-based transient search machine. In terms of performance, our GPU solution provides a speed-up factor of between 50 and 200, depending on the parameters of the search.

Magro, Alessio; Salvini, Stefano; Mort, Benjamin; Dulwich, Fred; Adami, Kristian Zarb

2011-01-01

226

Real-time, fast radio transient searches with GPU de-dispersion  

Science.gov (United States)

The identification and subsequent discovery of fast radio transients using blind-search surveys require a large amount of processing power, in worst cases scaling as ?. For this reason, survey data are generally processed off-line, using high-performance computing architectures or hardware-based designs. In recent years, graphics processing units (GPUs) have been extensively used for numerical analysis and scientific simulations, especially after the introduction of new high-level application programming interfaces. Here, we show how GPUs can be used for fast transient discovery in real time. We present a solution to the problem of de-dispersion, providing performance comparisons with a typical computing machine and traditional pulsar processing software. We describe the architecture of a real-time, GPU-based transient search machine. In terms of performance, our GPU solution provides a speed-up factor of between 50 and 200, depending on the parameters of the search.

Magro, A.; Karastergiou, A.; Salvini, S.; Mort, B.; Dulwich, F.; Zarb Adami, K.

2011-11-01

227

Study on influence of ratio between wideness and height of EMP simulator transmission line with fast rise-time to rise-time of EMP  

International Nuclear Information System (INIS)

The relation of rise-time inner EMP simulator with fast rise-time and ratio between wideness and height of simulator transmission line is studied through calculation of inner field of EMP simulator with fast rise-time and monadic linear regression analysis using FEKO based on MoM. The results indicate that there is close positive correlation between rise-time of EMP simulator with fast rise-time and the ratio between wideness and height. In other words, the larger the ratio of transmission line between wideness and height becomes, the longer the rise-time becomes. (authors)

228

Timing resolution of fast neutron and gamma counting with plastic microchannel plates  

Energy Technology Data Exchange (ETDEWEB)

The performance of novel plastic Microchannel plates (MCPs) with nano-engineered conduction and emission films have been shown to match the performance of conventional glass MCPs, widely used in image intensifying and event counting devices. In this paper we investigate the timing resolution of event detection with a 5 mm-thick polymethyl methacrylate (PMMA) microchannel plate with 50 {mu}m circular pores hexagonally packed at 70 {mu}m center-to-center spacing, which was developed for fast neutron detection. A detector consisting of the PMMA plastic MCP followed by a chevron stack of conventional glass MCPs for event multiplication was used in the timing experiments. The resolution of event counting was measured with Co-60 (1.17, 1.33 MeV {gamma}) source. The timing accuracy was derived from the time difference of event detection with plastic MCP and a detector with liquid scintillator (BC519) coupled to a photomultiplier tube. The measured {approx}4 ns FWHM timing accuracy of gamma photon counting agrees well with the results of our predictions performed with the help of a fully 3-dimensional model of the MCP amplification process. The same model and measurements of photon detection with conventional glass MCPs indicate that substantially better (sub-ns) accuracy can be achieved with smaller pores. Although we could not directly measure the timing accuracy of fast neutron detection with our plastic MCP due to the time of flight limitation of non-monoenergetic source the fast neutron timing resolution should be on the same scale due to the similarity of amplification process once the secondary electrons are produced within a pore.

Beaulieu, D.R.; Gorelikov, D.; Klotzsch, H. [Arradiance, Inc., 142 North Road, Sudbury, MA 01776 (United States); Legere, J.; Ryan, J. [Space Science Center, 330 Morse Hall, 8 College Road, University of New Hampshire, Durham, NH 03824 (United States); Rouffignac, P. de; Saadatmand, K.; Stenton, K.; Sullivan, N. [Arradiance, Inc., 142 North Road, Sudbury, MA 01776 (United States); Tremsin, A.S., E-mail: atremsin@arradiance.com [Arradiance, Inc., 142 North Road, Sudbury, MA 01776 (United States)

2011-12-11

229

A fast readout algorithm for Cluster Counting/Timing drift chambers on a FPGA board  

International Nuclear Information System (INIS)

A fast readout algorithm for Cluster Counting and Timing purposes has been implemented and tested on a Virtex 6 core FPGA board. The algorithm analyses and stores data coming from a Helium based drift tube instrumented by 1 GSPS fADC and represents the outcome of balancing between cluster identification efficiency and high speed performance. The algorithm can be implemented in electronics boards serving multiple fADC channels as an online preprocessing stage for drift chamber signals

230

A fast readout algorithm for Cluster Counting/Timing drift chambers on a FPGA board  

Science.gov (United States)

A fast readout algorithm for Cluster Counting and Timing purposes has been implemented and tested on a Virtex 6 core FPGA board. The algorithm analyses and stores data coming from a Helium based drift tube instrumented by 1 GSPS fADC and represents the outcome of balancing between cluster identification efficiency and high speed performance. The algorithm can be implemented in electronics boards serving multiple fADC channels as an online preprocessing stage for drift chamber signals.

Cappelli, L.; Creti, P.; Grancagnolo, F.; Pepino, A.; Tassielli, G.

2013-08-01

231

Development of a fast time-to-digital converter (TDC) using a programmable gate array  

International Nuclear Information System (INIS)

A fast time-to-digital converter with a 5 ns step was designed and tested by utilizing a user-programmable gate array. The stabilities against temperature and supply voltage variation were measured. A module was built with this TDC, and was successfully used in the first-level trigger system of the ZEUS detector to reject proton-beam induced background events. (author)

232

Time dependent solutions of the Fokker-Planck equation for fast fusion ions  

International Nuclear Information System (INIS)

Approximate time dependent solutions for the Fokker-Planck equation for fast fusion ions from an isotropic, monoenergetic source are presented, for the problem of D - T - He3 reactions. The equations include the effect of diffusion, which is particularly noticeable in the distribution of particles of lower energy and in the formation of a tail of particles with energy higher than that of the source. (Author)

233

Influence of Time-Dependent Coupling Coefficients and Delay Times on the Kinetics of a Modular Fast Reactor Core  

International Nuclear Information System (INIS)

Previous treatments of kinetics problems in modular and toroidal cores in fast breeder reactors have been based on Avery's coupled kinetics equations for partial integral fission sources. Most of these calculations do not take account of the time dependence of the reactivity coupling coefficients caused by possible flux tilting in an excursion. Furthermore, the effect of time delays for neutrons travelling between the modules, which is expected to be small, is not included in the model itself. The present investigation of the behaviour of two coupled modules is based on our recent derivation of coupled reactor kinetics equations from the Boltzmann equation. The distribution functions of delay times for neutrons are approximated by delta functions. It is shown that in three-group theory an analytical expression for the average delay time between two modules can still be derived. The calculation is based on the three-group leakage fluxes. Cross-sections are condensed from a 26-group set. Step changes in fission cross-sections are considered as perturbations. Coupling coefficients are calculated using the critical flux distribution and, to show the effect of time dependence, using the asymptotic flux distribution. Finally, a numerical method for solving coupled reactor kinetics equations is outlined. Comparing solutions of simple kinetics problems without feed-back but with time-dependent coupling coefficients and delay times to solutions without consideration of these two effects, it is found that the influence of neutron delay times is indeed negligible for the usual transients considered in the safety analysis of fast breeder reactors. However, the inclusion of time-dependent coupling coefficients can markedly alter the module power during an excursion. (author)

234

Sensitivity of firing rate to input fluctuations depends on time scale separation between fast and slow variables in single neurons.  

Science.gov (United States)

Neuronal responses are often characterized by the firing rate as a function of the stimulus mean, or the f-I curve. We introduce a novel classification of neurons into Types A, B-, and B+ according to how f-I curves are modulated by input fluctuations. In Type A neurons, the f-I curves display little sensitivity to input fluctuations when the mean current is large. In contrast, Type B neurons display sensitivity to fluctuations throughout the entire range of input means. Type B- neurons do not fire repetitively for any constant input, whereas Type B+ neurons do. We show that Type B+ behavior results from a separation of time scales between a slow and fast variable. A voltage-dependent time constant for the recovery variable can facilitate sensitivity to input fluctuations. Type B+ firing rates can be approximated using a simple "energy barrier" model. PMID:19353260

Lundstrom, Brian Nils; Famulare, Michael; Sorensen, Larry B; Spain, William J; Fairhall, Adrienne L

2009-10-01

235

Down-regulation of urinary AQP2 and unaffected response to hypertonic saline after 24 hours of fasting in humans  

DEFF Research Database (Denmark)

In rats, 24 hours of fasting impairs urinary concentrating ability by down-regulation of aquaporin-2 (AQP2). We tested the hypothesis that 24 hours of fasting in humans reduces the capability to form AQP2 and impairs the antidiuretic response to hypertonic saline infusion.

Starklint, JØrn; Bech, Jesper NØrgaard

2005-01-01

236

Performance and microbial response during the fast reactivation of Anammox system by hydrodynamic stress control.  

Science.gov (United States)

Anaerobic ammonium oxidation (Anammox) has become a promising method for biological nitrogen removal. However, this biotechnology application is always limited due to the low growth rate and biomass yield of Anammox bacteria. This study investigated the process of fast reactivation of an Anammox consortium idled for 2years via hydrodynamic stress control. The results showed that the Anammox system was efficiently and quickly reactivated by shortening of the hydraulic retention time (HRT) of the reactor from 12 to 6hr within 68days of operation. Moreover, at a 4-hr HRT with an influent total nitrogen loading rate of 1.2kg N/(m(3)·day), the reactor maintained high biological performance with an ammonium removal loading rate of 0.52kg N/(m(3)·day) and a nitrite removal rate of 0.59kg N/(m(3)·day). In the reactivated Anammox reaction, the stoichiometric coefficients of NH4(+)-N to NO2(-)-N and NH4(+)-N to NO3(-)-N were 1:1.04±0.08 and 1:0.31±0.03, respectively. The specific Anammox activity and hydrazine oxidoreductase activity, both of which represent the degree of Anammox bacteria present, increased as the hydrodynamic stress increased and were maximally (125.38±3.01mg N/(g VSS·day) and 339.42±6.83?mol/(min·g VSS), respectively) at 4-hr HRT. Microbial response analysis showed that the dominant microbial community was obviously shifted and the dominance of Anammox bacteria was enhanced during the hydrodynamic selection. PMID:25193835

Li, Yuan; Huang, Zhenxing; Ruan, Wenquan; Ren, Hongyan; Miao, Hengfeng

2014-09-01

237

The fast neutron response of 7LiF thermoluminescent dosemeters  

International Nuclear Information System (INIS)

A series of experiments was performed in 1982 to determine the neutron energy response of the 7LiF thermoluminescent dosemeter (TLD) employed in European zero power fast reactor gamma-ray energy deposition studies. Preliminary results of this work were included in a 1985 International experimental data-base of TLD neutron sensitivities and provided the most consistent set of data within the 7LiF compilation. A more detailed interpretation of these data has improved the results still further, giving a mean relative neutron to gamma efficiency of 0.118±0.005. The main objective of this re-evaluation was to establish recommended neutron energy response values to replace a 1974 data set for the analysis of in-core fast reactor measurements. This was achieved by combining the mean experimental relative efficiency of 0.118 with calculated energy dependent kerma factors. The kerma factors for the TLD were based on US National Bureau of Standards values and a composition determined by chemical analysis. Adoption of the revised neutron energy response data set produces a small increase in the measured gamma-ray energy deposition of typically 2% relative to the 1974 data. However, more importantly, the detailed analysis of the experimental response data has significantly improved confidence in the neutron corrections applied to in-core TLD gamma-ray energy deposition measurements. (author)

238

Do emergency medical system response times matter for health outcomes?  

Science.gov (United States)

The introduction of technology aimed at reducing the response times of emergency medical services has been one of the principal innovations in crisis care over the last several decades. These substantial investments have typically been justified by an assumed link between shorter response times and improved health outcomes. However, current medical research does not generally show a relationship between response time and mortality. In this study, we explain the discrepancy between conventional wisdom and mortality; existing medical research fails to account for the endogeneity of incident severity and response times. Analyzing detailed call-level information from the state of Utah's Bureau of Emergency Medical Services, we measure the impact of response time on mortality and hospital utilization using the distance of the incident from the nearest EMS agency headquarters as an instrument for response time. We find that response times significantly affect mortality and the likelihood of being admitted to the hospital, but not procedures or utilization within the hospital. PMID:22700368

Wilde, Elizabeth Ty

2013-07-01

239

Timing of response differentiation in human motor cortex during a speeded Go/No-Go task.  

Science.gov (United States)

We explored the brain's ability to quickly prevent a pre-potent but unwanted motor response. To address this, transcranial magnetic stimulation was delivered over the motor cortex (hand representation) to probe excitability changes immediately after somatosensory cues prompted subjects to either move as fast as possible or withhold movement. Our results showed a difference in motor cortical excitability 90ms post-stimulus contingent on cues to either promote or prevent movement. We suggest that our study design emphasizing response speed coupled with well-defined early probes allowed us to extend upon similar past investigations into the timing of response inhibition. PMID:24973619

Bolton, David A E; Vesia, Michael; Lakhani, Bimal; Staines, W Richard; McIlroy, William E

2014-08-01

240

INFLUENCE OF RAMADAN FASTING ON ANAEROBIC PERFORMANCE AND RECOVERY FOLLOWING SHORT TIME HIGH INTENSITY EXERCISE  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this study was to investigate the effects of Ramadan fasting on anaerobic power and capacity and the removal rate of lactate after short time high intensity exercise in power athletes. Ten male elite power athletes (2 wrestlers, 7 sprinters and 1 thrower, aged 20-24 yr, mean age 22.30 ± 1.25 yr) participated in this study. The subjects were tested three times [3 days before the beginning of Ramadan (Pre-RF), the last 3 days of Ramadan (End-RF) and the last 3 days of the 4th week a...

Umid Karli; Alpay Guvenc; Alper Aslan; Tahir Hazir; Caner Acikada

2007-01-01

 
 
 
 
241

Time Series Technical Analysis via new Fast Estimation Methods: A Preliminary Study in Mathematical Finance  

CERN Document Server

New fast estimation methods stemming from control theory lead to a fresh look at time series, which bears some resemblance to "technical analysis". The results are applied to a typical object of financial engineering, namely the forecast of foreign exchange rates, via a "model-free" setting, i.e., via repeated identifications of low order linear difference equations on sliding short time windows. Several convincing computer simulations, including the prediction of the position and of the volatility with respect to the forecasted trendline, are provided. $\\mathcal{Z}$-transform and differential algebra are the main mathematical tools.

Fliess, Michel

2008-01-01

242

A Fast Pulsed Neutron Source for Time-of-Flight Detection of Nuclear Materials and Explosives  

International Nuclear Information System (INIS)

AASC has built a fast pulsed neutron source based on the Dense Plasma Focus (DPF). The more current version stores only 100 J but fires at ?10-50 Hz and emits ?106n/pulse at a peak current of 100 kA. Both sources emit 2.45±0.1 MeV(DD) neutron pulses of ?25-40 ns width. Such fast, quasi-monoenergetic pulses allow time-of-flight detection of characteristic emissions from nuclear materials or high explosives. A test is described in which iron targets were placed at different distances from the point neutron source. Detectors such as Stilbene and LaBr3 were used to capture inelastically induced, 847 keV gammas from the iron target. Shielding of the source and detectors eliminated most (but not all) of the source neutrons from the detectors. Gated detection, pulse shape analysis and time-of-flight discrimination enable separation of gamma and neutron signatures and localization of the target. A Monte Carlo simulation allows evaluation of the potential of such a fast pulsed source for a field-portable detection system. The high rep-rate source occupies two 200 liter drums and uses a cooled DPF Head that is 3 in volume.

243

Recognition of stimulus-evoked neuronal optical response by identifying chaos levels of near-infrared spectroscopy time series.  

Science.gov (United States)

Near-infrared spectroscopy (NIRS) can detect two different kinds of signals from the human brain: the hemodynamic response (slow) and the neuronal response (fast). This paper explores a nonlinear aspect in the tactile-stimulus-evoked neuronal optical response over a NIRS time series (light intensity variation). The existence of the fast optical responses (FORs) over the time series recorded in stimulus sessions is confirmed by event-related averaging. The chaos levels of the NIRS time series recorded both in stimulus and in rest sessions are then identified according to the estimated largest Lyapunov exponent. The obtained results ascertain that stimulus-evoked neuronal optical responses can be detected in the somatosensory cortex using continuous-wave NIRS equipment. Further, the results strongly suggest that the chaos level can be used to recognize the FORs in NIRS time series and, thereby, the state of the pertinent brain activity. PMID:21945547

Hu, Xiao-Su; Hong, Keum-Shik; Ge, Shuzhi Sam

2011-10-24

244

Small-time asymptotics for fast mean-reverting stochastic volatility models  

CERN Document Server

In this paper, we study stochastic volatility models in regimes where the maturity is small but large compared to the mean-reversion time of the stochastic volatility factor. The problem falls in the class of averaging/homogenization problems for nonlinear HJB type equations where the "fast variable" lives in a non-compact space. We develop a general argument based on viscosity solutions which we apply to the two regimes studied in the paper. We derive a large deviation principle and we deduce asymptotic prices for Out-of-The-Money call and put options, and their corresponding implied volatilities. The results of this paper generalize the ones obtained in \\cite{FFF} (J. Feng, M. Forde and J.-P. Fouque, {\\it Short maturity asymptotic for a fast mean reverting Heston stochastic volatility model}, SIAM Journal on Financial Mathematics, Vol. 1, 2010) by a moment generating function computation in the particular case of the Heston model.

Feng, Jin; Kumar, Rohini

2010-01-01

245

Fast and Practical Head Tracking in Brain Imaging with Time-of-Flight Camera  

DEFF Research Database (Denmark)

This paper investigates the potential use of Time-of-Flight cameras (TOF) for motion correction in medical brain scans. TOF cameras have previously been used for tracking purposes, but recent progress in TOF technology has made it relevant for high speed optical tracking in high resolution medical scanners. Particularly in MRI and PET, the newest generation of TOF cameras could become a method of tracking small and large scale patient movement in a fast and user friendly way required in clinical environments. We present a novel methodology for fast tracking from TOF point clouds without the need of expensive triangulation and surface reconstruction. Tracking experiments with a motion controlled head phantom were performed with a translational tracking error below 2mm and a rotational tracking error below 0.5°.

Wilm, Jakob; Olesen, Oline Vinter

2013-01-01

246

Fast and practical head tracking in brain imaging with Time-of-Flight camera  

DEFF Research Database (Denmark)

This paper investigates the potential use of Time-of-Flight cameras (TOF) for motion correction in medical brain scans. TOF cameras have previously been used for tracking purposes, but recent progress in TOF technology has made it relevant for high speed optical tracking in high resolution medical scanners. Particularly in MRI and PET, the newest generation of TOF cameras could become a method of tracking small and large scale patient movement in a fast and user friendly way required in clinical environments. We present a novel methodology for fast tracking from TOF point clouds without the need of expensive triangulation and surface reconstruction. Tracking experiments with a motion controlled head phantom were performed with a translational tracking error below 2mm and a rotational tracking error below 0.5°.

Wilm, Jakob; Olesen, Oline Vinter

2013-01-01

247

INFLUENCE OF RAMADAN FASTING ON ANAEROBIC PERFORMANCE AND RECOVERY FOLLOWING SHORT TIME HIGH INTENSITY EXERCISE  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was to investigate the effects of Ramadan fasting on anaerobic power and capacity and the removal rate of lactate after short time high intensity exercise in power athletes. Ten male elite power athletes (2 wrestlers, 7 sprinters and 1 thrower, aged 20-24 yr, mean age 22.30 ± 1.25 yr participated in this study. The subjects were tested three times [3 days before the beginning of Ramadan (Pre-RF, the last 3 days of Ramadan (End-RF and the last 3 days of the 4th week after the end of Ramadan (After-RF]. Anaerobic power and capacity were measured by using the Wingate Anaerobic Test (WAnT at Pre-RF, End-RF and After- RF. Capillary blood samples for lactate analyses and heart rate recordings were taken at rest, immediately after WAnT and throughout the recovery period. Repeated measures of ANOVA indicated that there were no significant changes in body weight, body mass index, fat free mass, percentage of body fat, daily sleeping time and daily caloric intake associated with Ramadan fasting. No significant changes were found in total body water either, but urinary density measured at End-RF was significantly higher than After-RF. Similarity among peak HR and peak LA values at Pre-RF, End- RF and After-RF demonstrated that cardiovascular and metabolic stress caused by WAnT was not affected by Ramadan fasting. In addition, no influence of Ramadan fasting on anaerobic power and capacity and removal rate of LA from blood following high intensity exercise was observed. The results of this study revealed that if strength-power training is performed regularly and daily food intake, body fluid balance and daily sleeping time are maintained as before Ramadan, Ramadan fasting will not have adverse effects on body composition, anaerobic power and capacity, and LA metabolism during and after high intensity exercise in power athletes

Umid Karli

2007-12-01

248

28 CFR 542.18 - Response time.  

Science.gov (United States)

...on the date it is logged into the Administrative Remedy Index as received. Once filed, response shall be made by the Warden or CCM within 20 calendar days; by the Regional Director within 30 calendar days; and by the General Counsel within 40 calendar...

2010-07-01

249

A novel method for fast Change-Point detection on simulated time series and electrocardiogram data.  

Science.gov (United States)

Although Kolmogorov-Smirnov (KS) statistic is a widely used method, some weaknesses exist in investigating abrupt Change Point (CP) problems, e.g. it is time-consuming and invalid sometimes. To detect abrupt change from time series fast, a novel method is proposed based on Haar Wavelet (HW) and KS statistic (HWKS). First, the two Binary Search Trees (BSTs), termed TcA and TcD, are constructed by multi-level HW from a diagnosed time series; the framework of HWKS method is implemented by introducing a modified KS statistic and two search rules based on the two BSTs; and then fast CP detection is implemented by two HWKS-based algorithms. Second, the performance of HWKS is evaluated by simulated time series dataset. The simulations show that HWKS is faster, more sensitive and efficient than KS, HW, and T methods. Last, HWKS is applied to analyze the electrocardiogram (ECG) time series, the experiment results show that the proposed method can find abrupt change from ECG segment with maximal data fluctuation more quickly and efficiently, and it is very helpful to inspect and diagnose the different state of health from a patient's ECG signal. PMID:24690633

Qi, Jin-Peng; Zhang, Qing; Zhu, Ying; Qi, Jie

2014-01-01

250

Verification of the CNGS Timing System using Ultra-Fast Diamond Detectors  

CERN Document Server

A new ultra-fast diagnostic tool was installed in the CNGS facility in 2011 following the neutrino time-of-flight results published by OPERA in September 2011. Several polycrystalline CVD diamond detectors were placed in the secondary beam line about 1200m downstream of the CNGS target in order to measure the time structure of the muons which are produced together with the muon neutrinos. This allows an accurate measurement of the GPS timing of individual secondary particle bunches crossing these detectors, and provides an independent timing measurement at CERN, which has previously been based solely on the fast beam current transformers installed in the primary proton beam line upstream of the CNGS target. Both the position of the detectors, and the time between the detection of the particles at the beam current transformer and the diamond detectors have been measured very carefully and a sound analysis of the detector signals was done. This allows comparison of the measurements between the beam current tran...

Jansen, H; Bart Pedersen, S; Dehning, B; Dobos, D; Effinger, E; Ferrari, A; Griesmayer, E; Gschwendtner, E; Kozsar, I; Missiaen, D; Pernegger, H; Sala, P R; Serrano, J; Ward, C

2012-01-01

251

Exupéry - a mobile fast response system for managing a volcanic crisis  

Science.gov (United States)

Despite ever increasing efforts to monitor historically active volcanoes many of those are still very poorly or unmonitored, even in highly populated areas. In case of volcanic unrest or even a volcanic crisis evaluating the situation is therefore often very difficult due to the little information that is available for that specific volcano. Over the past decades several different programs have supported volcanic crisis management efforts in third world countries from sending experts all the way to improving or even installing new networks around the volcano. One of the main problems especially when quickly upgrading networks during a crisis is that each system usually comes with its own acquisition and processing system which makes it very difficult to manage the observational network and provide an interdisciplinary interpretation of the data with respect to the activity status of the volcano. Here we present a newly developed volcano fast response system which overcomes several of these shortcomings. The core of the system is a novel database (SEISHUB) that allows for the collection of data of various kinds, i.e. simple time series data like seismic data, gas measurements, GPS measurements, as well as satellite data (SO2 flux, thermal anomaly, ground deformation). Part of the collected data may also come from an already existing network. Data from new field instruments are transmitted through a wireless network that has been specifically designed for the volcano fast response system. One of the main difficulties with such a multidisciplinary data set is an easy access to the data. This is provided through a common Web based GIS interface which allows various datalayers being simultaneously accessed through a Web Browser. The underlying software is designed in such a way that it only uses open source software, so it can be easily installed on other systems not having to deal with purchasing proprietary software. Aside from this the system provides tools to analyze the incoming data (e.g. earthquake classification, rapid moment tensor inversion, deformation modeling, an automatic alert level system) which are currently under development. Exupery Working Group: Barsch R (2); Bernsdorf S (3); Beyreuther M (2); Cong X (4); Dahm T (1); Eineder M (4); Erbertseder T (4); Gerstenecker C (5); Hammer C (6); Hansteen T (7); Krieger L (1); Läufer G (5); Maerker C (4); Montalvo Garcia A (1); Ohrnberger M (6); Rix M (4); Rödelsperger S (5); Seidenberger K (4); Shirzaei M (8); Stammler K (9); Stittgen H (9); Valks P (4); Walter T (8); Wallenstein N (10); Wassermann J (2); Zakšek K (1) (1)Institute of Geophysics, Hamburg, Germany; (2) Department of Earth and Environmental Sciences, Geophysical Observatory, Munich, Germany; (3)Centauron - geosoftware & consulting, Weimar, Germany; (4)DLR Oberpfaffenhofen, Germany; (5)Institute of Physical Geodesy, Darmstadt, Germany; (6)Institute of Geosciences, Potsdam, Germany; (7) IFM-GEOMAR, Leibniz Institute of Marine Sciences, Germany; (8)Department physics of the earth, GFZ, Potsdam, Germany; (9)BGR, Geocentre Hannover, Germany; (10)CVARG, Universidade Dos Acores; Portugal

Hort, M. K.

2009-12-01

252

Efficient allocation of heterogeneous response times in information spreading process  

CERN Document Server

Recently, the impacts of spatiotemporal heterogeneities of human activities on spreading dynamics have attracted extensive attention. In this paper, to study heterogeneous response times on information spreading, we focus on the susceptible-infected spreading dynamics with adjustable power-law response time distribution based on uncorrelated scale-free networks. We find that the stronger the heterogeneity of response times is, the faster the information spreading is in the early and middle stages. Following a given heterogeneity, the procedure of reducing the correlation between the response times and degrees of individuals can also accelerate the spreading dynamics in the early and middle stages. However, the dynamics in the late stage is slightly more complicated, and there is an optimal value of the full prevalence time changing with the heterogeneity of response times and the response time-degree correlation, respectively. The optimal phenomena results from the efficient allocation of heterogeneous respon...

Cui, Ai-Xiang; Tang, Ming; Fu, Yan; Liang, Xiaoming; Do, Younghae

2014-01-01

253

Modeling and testing of fast response, fiber-optic temperature sensors  

Science.gov (United States)

The objective of this work was to design, analyze and test a fast response fiber-optic temperature probe and sensor. The sensor is intended for measuring rapid temperature changes such as produced by a blast wave formed by a detonation. This work was performed in coordination with Luna Innovations Incorporated, and the design is based on extensions of an existing fiber-optic temperature sensor developed by Luna. The sensor consists of a glass fiber with an optical wafer attached to the tip. A basic description of the principles behind the fiber-optic temperature sensor and an accompanying demodulation system is provided. For experimental validation tests, shock tubes were used to simulate the blast wave experienced at a distance of 3.0 m from the detonation of 22.7 kg of TNT. The flow conditions were predicted using idealized shock tube theory. The temperature sensors were tested in three configurations, flush at the end of the shock tube, extended on a probe 2.54 cm into the flow and extended on a probe 12.7 cm into the flow. The total temperature was expected to change from 300 K to 1130 K for the flush wall experiments and from 300 K to 960 K for the probe experiments. During the initial 0.1 milliseconds of the data the temperature only changed 8 K when the sensors were flush in the end of the shock tube. The sensor temperature changed 36 K during the same time when mounted on a probe in the flow. Schlieren pictures were taken of the flow in the shock tube to further understand the shock tube environment. Contrary to ideal shock tube theory, it was discovered that the flow did not remain stagnant in the end of the shock tube after the shock reflects from the end of the shock tube. Instead, the effects of turbulence were recorded with the fiber-optic sensors, and this turbulence was also captured in the schlieren photographs. A fast-response thermocouple was used to collect data for comparison with the fiber-optic sensor, and the fiber-optic sensor was proven to have a faster response time compared to the thermocouple. When the sensors were extended 12.7 cm into the flow, the fiber-optic sensors recorded a temperature change of 143 K compared to 38 K recorded by the thermocouple during the 0.5 millisecond test. This corresponds to 22% of the change of total temperature in the air recorded by the fiber-optic sensor and only 6% recorded by the thermocouple. Put another way, the fiber-optic sensor experience a rate of temperature change equal to 2.9x105 K/s and the thermocouple changed at a rate of 0.79x105 K/s. The data recorded from the fiber-optic sensor also contained much less noise than the thermocouple data. An unsteady finite element thermal model was created using ANSYS to predict the temperature response of the sensor. Test cases with known analytical solutions were used to verify the ANSYS modeling procedures. The shock tube flow environment was also modeled with Fluent, a commercially available CFD code. Fluent was used to determine the heat transfer between the shock tube flow and the sensor. The convection film coefficient for the flow was predicted by Fluent to be 27,150 W/m2K for the front of the wafer and 13,385 W/m2K for the side. The Fluent results were used with the ANSYS model to predict the response of the fiber-optic sensor when exposed to the shock tube flow. The results from the Fluent/ANSYS model were compared to the fiber-optic measurements taken in the shock tube. It was seen that the heat flux to the sensor was slightly over-predicted by the model, and the heat losses from the wafer were also over-predicted. Since the prediction fell within the uncertainty of the measurement, it was found to be in good agreement with the measured values. (Abstract shortened by UMI.)

Tonks, Michael James

254

A Unified Constitutive Relationship for the Time-dependent Behavior of Fast Breeder Alloys  

Science.gov (United States)

Constitutive equations based on classical concepts of creep and plasticity generally rest on the assumption that the inelastic strain can be decomposed into two distinct and additive contributions, one time dependent (creep) and the other time dependent (plastic). It is suggested that an approach is to adopt a unified representation in which creep and plasticity are characterized as occurring simultaneously and interactively and time is an essential ingredient throughout. Examples of the inherent time dependency exhibited by some fast breeder alloys at elevated temperature are rate dependency under monotonic and cyclic straining, thermal recovery and strong creep-elasticity interaction. The stron influence of the recent history of plastic straining on stress relaxation is shown.

Robinson, D. N.

1983-01-01

255

Event synchronization a simple and fast method to measure synchronicity and time delay patterns  

CERN Document Server

We propose a simple method to measure synchronization and time delay patterns between signals. It is based on the relative timings of events in the time series, defined e.g. as local maxima. The degree of synchronization is obtained from the number of quasi-simultaneous appearances of events, and the delay is calculated from the precedence of events in one signal with respect to the other. Moreover, we can easily visualize the time evolution of the delay and synchronization level with an excellent resolution. We apply the algorithm to short rat EEG signals, some of them containing spikes. We also apply it to an intracranial human EEG recording containing an epileptic seizure, and we propose that the method might be useful for the detection of foci and for seizure prediction. It can be easily extended to other types of data and it is very simple and fast, thus being suitable for on-line implementations.

Quiroga, R Q; Grassberger, Peter

2002-01-01

256

Response of multiferroic composites inferred from a fast-Fourier-transform-based numerical scheme  

International Nuclear Information System (INIS)

The effective response and the local fields within periodic magneto-electric multiferroic composites are investigated by means of a numerical scheme based on fast Fourier transforms. This computational framework relies on the iterative resolution of coupled series expansions for the magnetic, electric and strain fields. By using an augmented Lagrangian formulation, a simple and robust procedure which makes use of the uncoupled Green operators for the elastic, electrostatics and magnetostatics problems is proposed. Its accuracy is assessed in the cases of laminated and fibrous two-phase composites for which analytical solutions exist

257

Fast-response high-precise photometry system for automated microdensitometer  

International Nuclear Information System (INIS)

A system intended for measurement of optical density (transmission coefficient) of black-while images in the 0-4 range as well as zonal optical densities of colored images in the 0.2.5 range is described. Fast response of the system makes up 10000 measurements/s error of measurement does not exceed 1%. The block-diagram of the whole system and basic circuits of separate units are considered. Results of experimental study are presented. The system is utilized in an automatic microdensitometer; it can be also applied in other devices of similar purpose

258

Development of a LaBr3(Ce) Fast-timing Array for FAIR  

International Nuclear Information System (INIS)

A ?-ray spectrometer with fast-timing capabilities, constructed of LaBr3(Ce:5%) detectors, is under development for use at the future Facility for Anti-proton and Ion Research (FAIR). The physics aims of this device are to measure the half-lives of excited states in the region of ?50 ps to several ns, in exotic nuclei. Monte-Carlo simulations using the GEANT4 software package have determined the final design of this fast-timing array by calculating the full-energy peak efficiencies of several different detector geometries. The results of the simulated efficiencies for each configuration were used to calculate the timing precision. Consequently, an array of thirty six, section 3.8 x 5.1 cm cylindrical crystals was found to be the optimum configuration. The detectors were purchased and subsequently characterised, with each detector found to have intrinsic energy and timing resolutions of ? 2.8 % (FWHM) and ? 210 ps (FWHM) for the 1173 and 1332 keV decays from 60Co. (authors)

259

Thermal remote sensing as a part of Exupéry volcano fast response system  

Science.gov (United States)

In order to understand the eruptive potential of a volcanic system one has to characterize the actual state of stress of a volcanic system that involves proper monitoring strategies. As several volcanoes in highly populated areas especially in south east Asia are still nearly unmonitored a mobile volcano monitoring system is currently being developed in Germany. One of the major novelties of this mobile volcano fast response system called Exupéry is the direct inclusion of satellite based observations. Remote sensing data are introduced together with ground based field measurements into the GIS database, where the statistical properties of all recorded data are estimated. Using physical modelling and statistical methods we hope to constrain the probability of future eruptions. The emphasis of this contribution is on using thermal remote sensing as tool for monitoring active volcanoes. One can detect thermal anomalies originating from a volcano by comparing signals in mid and thermal infrared spectra. A reliable and effective thermal anomalies detection algorithm was developed by Wright (2002) for MODIS sensor; it is based on the threshold of the so called normalized thermal index (NTI). This is the method we use in Exupéry, where we characterize each detected thermal anomaly by temperature, area, heat flux and effusion rate. The recent work has shown that radiant flux is the most robust parameter for this characterization. Its derivation depends on atmosphere, satellite viewing angle and sensor characteristics. Some of these influences are easy to correct using standard remote sensing pre-processing techniques, however, some noise still remains in data. In addition, satellites in polar orbits have long revisit times and thus they might fail to follow a fast evolving volcanic crisis due to long revisit times. Thus we are currently testing Kalman filter on simultaneous use of MODIS and AVHRR data to improve the thermal anomaly characterization. The advantage of this technique is that it increases the temporal resolution through using images from different satellites having different resolution and sensitivity. This algorithm has been tested for an eruption at Mt. Etna (2002) and successfully captures more details of the eruption evolution than would be seen by using only one satellite source. At the moment for Exupéry, merely MODIS (a sensor aboard NASA's Terra and Aqua satellite) data are used for the operational use. As MODIS is a meteorological sensor, it is suitable also for producing general overview images of the crisis area. Therefore, for each processed MODIS image we also produce RGB image where some basic meteorological features are classified: e.g. clouds, volcanic ash plumes, ocean, etc. In the case of detected hotspot an additional image is created; it contains the original measured radiances of the selected channels for the crisis area. All anomaly and processing parameters are additionally written into an XML file. The results are available in web GIS in the worst case two hours after NASA provides level 1b data online.

Zakšek, Klemen; Hort, Matthias

2010-05-01

260

A CFD-based wind solver for a fast response transport and dispersion model  

Energy Technology Data Exchange (ETDEWEB)

In many cities, ambient air quality is deteriorating leading to concerns about the health of city inhabitants. In urban areas with narrow streets surrounded by clusters of tall buildings, called street canyons, air pollution from traffic emissions and other sources is difficult to disperse and may accumulate resulting in high pollutant concentrations. For various situations, including the evacuation of populated areas in the event of an accidental or deliberate release of chemical, biological and radiological agents, it is important that models should be developed that produce urban flow fields quickly. For these reasons it has become important to predict the flow field in urban street canyons. Various computational techniques have been used to calculate these flow fields, but these techniques are often computationally intensive. Most fast response models currently in use are at a disadvantage in these cases as they are unable to correlate highly heterogeneous urban structures with the diagnostic parameterizations on which they are based. In this paper, a fast and reasonably accurate computational fluid dynamics (CFD) technique that solves the Navier-Stokes equations for complex urban areas has been developed called QUIC-CFD (Q-CFD). This technique represents an intermediate balance between fast (on the order of minutes for a several block problem) and reasonably accurate solutions. The paper details the solution procedure and validates this model for various simple and complex urban geometries.

Gowardhan, Akshay A [Los Alamos National Laboratory; Brown, Michael J [Los Alamos National Laboratory; Pardyjak, Eric R [UNIV OF UTAH; Senocak, Inanc [BOISE STATE UNIV

2010-01-01

 
 
 
 
261

Sources of uncertainty in eddy covariance ozone flux measurements made by dry chemiluminescence fast response analysers  

Directory of Open Access Journals (Sweden)

Full Text Available Eddy covariance ozone flux measurements are the most direct way to estimate ozone removal near the surface. Over vegetated surfaces, high quality ozone fluxes are required to probe the underlying processes for which it is necessary to separate the flux into the components of stomatal and non-stomatal deposition. Detailed knowledge of the processes that control non-stomatal deposition is limited and more accurate ozone flux measurements are needed to quantify this component of the deposited flux. We present a systematic intercomparison study of eddy covariance ozone flux measurements made using two fast response dry chemiluminescence analysers. Ozone deposition was measured over a well characterised managed grassland near Edinburgh, Scotland, during August 2007. A data quality control procedure specific to these analysers is introduced. Absolute ozone fluxes were calculated based on the relative signals of the dry chemiluminescence analysers using three different calibration methods and the results are compared for both analysers. It is shown that the error in the fitted parameters required for the flux calculations provides a substantial source of uncertainty in the fluxes. The choice of the calculation method itself can also constitute an uncertainty in the flux as the calculated fluxes by the three methods do not agree within error at all times. This finding highlights the need for a consistent and rigorous approach for comparable data-sets, such as e.g. in flux networks. Ozone fluxes calculated by one of the methods were then used to compare the two analysers in more detail. This systematic analyser comparison reveals half-hourly flux values differing by up to a factor of two at times with the difference in mean hourly flux ranging from 0 to 23% with an error in the mean daily flux of ±12%. The comparison of analysers shows that the agreement in fluxes is excellent for some days but that there is an underlying uncertainty as a result of variable analyser performance and/or non-linear behaviour of disc sensitivity.

J. B. A. Muller

2009-09-01

262

The Importance of Responsibility in Times of Crisis  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper I would like to show the importance of the concept of responsibility as the foundation of ethics in times of crisis in particular in the fields of politics and economics in the modern civilisation marked by globalization and technological progres. I consider the concept of responsibility as the key notion in order to understand the ethical duty in a modern technological civilisation. We can indeed observe a moralization of the concept of responsibility going beyond a strict legal definition in terms of imputability. The paper begins by discussing the humanistic foundations of such a concept of responsibility. It treats the historical origins of responsibility and it relates this concept to the concept of accountability. On the basis of this historical determination of the concept I would like to present the definition of the concept of responsibility as fundamental ethical principle that has increasing importance as the foundation of the principles of governance in modern welfare states. In this context the paper discusses the extension of the concept of responsibility towards institutional or corporate responsibility where responsibility does not only concerns the responsibility of individuals but also deals with the responsibility of institutional collectivities. In this way the paper is based on the following structure : 1 The ethical foundation of the concept of responsibility 2 Responsibility in technological civilisation 3 Political responsibility for good governance in the welfare state 4 Social responsibility of business corporations in times of globalization 5 Conclusion and discussion : changed conditions of responsibility in modern times.

Jacob Dahl Rendtorff

2014-06-01

263

Effects of Ramadan on physical capacities of North African boys fasting for the first time  

Science.gov (United States)

Introduction Most of the literature related to the effects of Ramadan fasting on physical performance has focused on adults, and only three studies have examined its impact on children’s physical performance. Aims To examine the effects of Ramadan fasting on first-time fasting boys’ performance in short-term explosive exercises [vertical and horizontal jump tests (VJT and HJT), 20-m and 30-m sprints and medicine-ball throw (MBT)], as well as in sub-maximal endurance [6-min walking distance (6MWD) measured during the 6-min walk test (6MWT)]. Methods Eighteen Tunisian boys [mean±standard deviation (SD) of age and body mass (BM): 11.9±0.8 y and 55.4±18.2 kg, respectively] were included. The experimental design comprised four testing phases: 2-weeks before Ramadan (BR), the end of the second week (R2) and the fourth week (R4) of Ramadan, and 10–12 days after the end of Ramadan (AR). At each phase, boys performed two test sessions in the afternoon (15:00–17:00 h) interrupted by 48 h of recovery (first test session: BM, VJT, HJT, and 20-m and 30-m sprint tests; second session: MBT and 6MWT). The study was conducted during the summer of 2012 from July 5 to August 29. Results 6MWDs (m) were significantly shorter during R2 (652±101) and R4 (595±123) compared to BR (697±86) and came back to baseline values AR. BM (kg) mean±SD did not significantly change during R2 (52±15) and during R4 (53±15) compared to BR (55±17), and short-term explosive performances were unchanged throughout the study. Conclusion In non-athletic children, first-ever Ramadan fasting impairs sub-maximal aerobic capacity but has no effect on BM or short-term explosive performance. PMID:25261691

Fenneni, Mohamed A.; Latiri, Imed; Aloui, Asma; Rouatbi, Sonia; Saafi, Mohamed A.; Bougmiza, Iheb; Chamari, Karim; Saad, Helmi Ben

2014-01-01

264

Response times of operators in a control room  

International Nuclear Information System (INIS)

A statistical analysis was made of operator response times recorded in the control room of a research reactor during the years 1972-1974. A homogeneity test revealed that the data consist of a mixture of populations. A small but statistically significant difference is found between day and night response times. Lognormal distributions are found to provide the best fit of the day and the night response times. (author)

265

Modeling response times with latent variables: Principles and applications  

Directory of Open Access Journals (Sweden)

Full Text Available The introduction of the computer in psychological and educational testing has enabled us to record response times on test items in real time, without any interruption of the response process. This article reviews key principles for probabilistic modeling of these response times and discusses a hierarchical model that follows from the principles. It then shows the potential of the model for improving the current practices of item calibration, adaptive testing, controlling test speededness, and detection of cheating.

2011-09-01

266

The arrival direction of energetic cosmic rays measured with a fast timing Cerenkov light technique  

International Nuclear Information System (INIS)

The accurate arrival directions of air showers (0) available from a fast timing Cerenkov light experiment are used to search for point sources of ultra high energy ?-rays. The data span the energy range 5 x 1015 eV - 1017 eV and were recorded in the period 1977-1980 at Dugway, Utah. Most of the exposure was of the Galactic anticentre region. Flux limits of approximately 10-13 to approximately 2 x 10-15 cm-2 sec-1 for primaries of energy >= 3 x 1015 to >=1017 eV from the Crab nebula have been determined

267

Fast imaging of marine controlled-source EM data using time domain electromagnetic migration  

Science.gov (United States)

The application of electromagnetic (EM) methods in petroleum and mining exploration requires development of appropriate imaging techniques, which provide the means for fast but accurate evaluation of the observed data. Time domain electromagnetic (TDEM) methods are widely used in geophysical exploration. However, practical interpretation of TDEM data is mainly based on a simple one-dimensional (1D) inversion of the data at any given observation point. Due to increased interest in the time-domain technique in offshore petroleum exploration with a controlled-source of the EM field, the development of multidimensional interpretation of TDEM data is required. In this paper, a fast approach to TDEM data interpretation using the method of TDEM migration is introduced. The computation of the migration field is based on downward extrapolation of the observed field in reverse time. An effective method of EM migration based on the operator of an integral transformation in the spatial-temporal domain is examined. A migration geoelectrical image is constructed using the convolution of the background and migration fields. Also, the technique is extended for interpretation of TDEM data observed both in land surveys with layered background media and in marine hydrocarbon exploration by introducing an adjoint land geoelectrical model for a given model and a corresponding adjoint field. The accuracy of this imaging technique is demonstrated successfully using synthetic TDEM data simulating mining exploration and hydrocarbon exploration in land and marine survey environments, respectively. The results ensure that this imaging technique works reasonably well.

Endo, M.; Furukawa, T.; Zhdanov, M. S.

2008-12-01

268

Liquid-metal fast breeder reactor core transient modeling for faster than real-time analysis  

International Nuclear Information System (INIS)

A model was developed for faster than real-time liquid-metal fast breeder reactor core transient analysis for purposes of continuous on-line data validation, plant state verification, and fault identification. The basic feature of this model is the use of a nodal approximation for the coolant, cladding, and fuel temperatures that gives adequately accurate power and temperature predictions with very few axial nodes. In applications of this methodology to fast loss-of-flow and overpower transients, computation times of about one-thirtieth of the real transient time per thermal-hydraulic channel were obtained. The predicted coolant and cladding temperature distributions were practically identical to those resulting from detailed finite difference computations. The predicted fuel temperatures differed by -- 1% or less from those obtained from the same finite difference computations. The analysis of the Transient Reactor Test Facility experiment TS-1C and the Experimental Breeder Reactor II experiment SHRT-17 showed very good agreement between model predictions and measurements

269

Fast elaboration of diagnostic data for real time control in FTU tokamak  

Directory of Open Access Journals (Sweden)

Full Text Available The automatic controller developed for MHD instability control on FTU via the real time (RT EC launcher [1, 2] is based on the a-priori estimate of the instabilities location and on the fast elaboration of the stream of diagnostic data. A fast data acquisition system, based on existing standard FTU diagnostics, collects thermal and magnetic signals by a 12-channels ECE polychromator [3] and by a set of 22 Mirnov coils respectively. Moreover, the EC time waveform from directional couplers along the transmission line is acquired as well. This set of signals is processed in a timescale significantly shorter than the typical time step of the controller (1ms. RT elaboration algorithms aim at supplying the controller [4] with reliable information about the existence and the spatial location of the instability and about the actual ECRH deposition layer in plasma. The main algorithms blocks are ECE-ECE, ECE-Mirnov and ECE-ECRH cross-correlation, and SVD (Singular Value Decomposition of Mirnov signals. The capabilities of effective detection, false positive resilience, and mode discrimination will be discussed through the application to actual plasma data.

Nowak S.

2012-09-01

270

Technical Proposal for the ALICE START Fast Timing Detector Based on Fine-Mesh Phototubes  

CERN Document Server

Technical Proposal for the ALICE START Fast Timing Detector Based on Fine-Mesh Phototubes A scintillation detector based on fine-mesh phototubes with good timing proporties ( ~ 50 ps) is proposed as a complementary detector for two existing options of the ALICE Forward Multiplicity Detector. Experimental results show high time resolution (up to 35 ps) and high gain in a magnetic field up to 0.5 T of fine-mesh Russian phototubes FEU-527. The proposed detector consists of two arrays of scintillation (or Cherenkov) counters, 24 counters each. The Monte-Carlo simulations made for the proposed design of the detector for p-p collisions give the average efficiency of the detector about 80%. The physical characteristics of the proposed detector are compared with those expected for the MCP version of the FMD.

Kaplin, V A; CERN. Geneva; Loginov, V A; Strikhanov, M N; Gavrilov, Yu K; Filippov, S N; Kurepin, A B; Mayevskaya, A I

1997-01-01

271

Concatenated Space-Time Block Coding with Asymmetric MPSK TCM for Fast Fading Channels  

Directory of Open Access Journals (Sweden)

Full Text Available The field of concatenated space-time block coding (inner with trellis coded modulation (outer has recently attracted interest as a means of jointly considering the error correction coding gain and diversity gain possible without bandwidth expansion and power expansion over fading channels. In this research, a concatenated Space-Time Block Coding (STBCwith asymmetric MPSK TCM scheme, based on the design criteria for constructing concatenated space-time block coding with TCM for fast Rayleigh fading channels, is presented by introducing the new optimal signal point assignment. Using parameter comparison and simulation results, the proposed concatenated STBC with asymmetric MPSK TCM is shown to have better coding gain than traditional concatenated STBC with TCM under the same spectral efficiency, decoding complexity.

Ao Ju

2008-01-01

272

Using Graphs for Fast Error Term Approximation of Time-varying Datasets  

Energy Technology Data Exchange (ETDEWEB)

We present a method for the efficient computation and storage of approximations of error tables used for error estimation of a region between different time steps in time-varying datasets. The error between two time steps is defined as the distance between the data of these time steps. Error tables are used to look up the error between different time steps of a time-varying dataset, especially when run time error computation is expensive. However, even the generation of error tables itself can be expensive. For n time steps, the exact error look-up table (which stores the error values for all pairs of time steps in a matrix) has a memory complexity and pre-processing time complexity of O(n2), and O(1) for error retrieval. Our approximate error look-up table approach uses trees, where the leaf nodes represent original time steps, and interior nodes contain an average (or best-representative) of the children nodes. The error computed on an edge of a tree describes the distance between the two nodes on that edge. Evaluating the error between two different time steps requires traversing a path between the two leaf nodes, and accumulating the errors on the traversed edges. For n time steps, this scheme has a memory complexity and pre-processing time complexity of O(nlog(n)), a significant improvement over the exact scheme; the error retrieval complexity is O(log(n)). As we do not need to calculate all possible n2 error terms, our approach is a fast way to generate the approximation.

Nuber, C; LaMar, E C; Pascucci, V; Hamann, B; Joy, K I

2003-02-27

273

The ITER Fast Plant System Controller ATCA prototype Real-Time Software Architecture  

Energy Technology Data Exchange (ETDEWEB)

Highlights: ? High performance ATCA systems for fast control and data acquisition. ? IEEE1588 timing system and synchronization. ? Plasma control algorithms. ? Real-time control software frameworks. ? Targeted for nuclear fusion experiments with long duration discharges. -- Abstract: IPFN is developing a prototype Fast Plant System Controller (FPSC) based in ATCA embedded technologies dedicated to ITER CODAC data acquisition and control tasks in the sub-millisecond range. The main goal is to demonstrate the usability of the ATCA standard and its enhanced specifications for the high speed, very high density parallel data acquisition needs of the most demanding ITER tokamak plasma Instrumentation and Control (I and C) systems. This effort included the in-house development of a new family of high performance ATCA I/O and timing boards. The standard ITER software system CODAC Core System (CCS) v3.1, with the control based in the EPICS system does not cover yet the real-time requirements fulfilled by this hardware, so a new set of software components was developed for this specific platform, attempting to integrate and leverage the new features in CSS, for example the Multithreaded Application Real Time executor (MARTe) software framework, the new Data Archiving Network (DAN) solution, an ATCA IEEE-1588-2008 timing interface, and the Intelligent Platform Management Interface (IPMI) for system monitoring and remote management. This paper presents the overall software architecture for the ATCA FPSC, as well a discussion on the ITER constrains and design choices and finally a detailed description of the software components already developed.

Carvalho, B.B., E-mail: bernardo@ipfn.ist.utl.pt [Associacao EURATOM/IST Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, P-1049-001 Lisboa (Portugal); Santos, B.; Carvalho, P.F.; Neto, A. [Associacao EURATOM/IST Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, P-1049-001 Lisboa (Portugal); Boncagni, L. [Associazione Euratom-ENEA sulla Fusione, Frascati Research Centre, Division of Fusion Physics, Frascati, Rome (Italy); Batista, A.J.N.; Correia, M.; Sousa, J.; Gonçalves, B. [Associacao EURATOM/IST Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, P-1049-001 Lisboa (Portugal)

2013-10-15

274

The ITER Fast Plant System Controller ATCA prototype Real-Time Software Architecture  

International Nuclear Information System (INIS)

Highlights: ? High performance ATCA systems for fast control and data acquisition. ? IEEE1588 timing system and synchronization. ? Plasma control algorithms. ? Real-time control software frameworks. ? Targeted for nuclear fusion experiments with long duration discharges. -- Abstract: IPFN is developing a prototype Fast Plant System Controller (FPSC) based in ATCA embedded technologies dedicated to ITER CODAC data acquisition and control tasks in the sub-millisecond range. The main goal is to demonstrate the usability of the ATCA standard and its enhanced specifications for the high speed, very high density parallel data acquisition needs of the most demanding ITER tokamak plasma Instrumentation and Control (I and C) systems. This effort included the in-house development of a new family of high performance ATCA I/O and timing boards. The standard ITER software system CODAC Core System (CCS) v3.1, with the control based in the EPICS system does not cover yet the real-time requirements fulfilled by this hardware, so a new set of software components was developed for this specific platform, attempting to integrate and leverage the new features in CSS, for example the Multithreaded Application Real Time executor (MARTe) software framework, the new Data Archiving Network (DAN) solution, an ATCA IEEE-1588-2008 timing interface, and the Intelligent Platform Management Interface (IPMI) for system monitoring and remote management. This paper presents the overall software architecture for the ATCA FPSC, as well a discussion on the ITER constrains and design choices and finally a detailed description of the software components already developed

275

Dynamic Response of a fast near infra-red Mueller matrix ellipsometer  

CERN Document Server

The dynamic response of a near infrared Ferroelectric Liquid Crystal based Mueller matrix ellipsometer (NIR FLC-MME) is presented. A time dependent simulation model, using the measured time response of the individual FLCs, is used to describe the measured temporal response. Furthermore, the impulse response of the detector and the pre-amplifier is characterized and included in the simulation model. The measured time-dependent intensity response of the MME is reproduced in simulations, and it is concluded that the switching time of the FLCs is the limiting factor for the Mueller matrix measurement time of the FLC-based MME. Based on measurements and simulations our FLC based NIR-MME system is estimated to operate at the maximum speed of approximately 16 ms per Mueller matrix measurement. The FLC-MME may be operated several times faster, since the switching time of the crystals depends on the individual crystal being switched, and to what state it is switched. As a demonstration, the measured temporal response ...

Aas, Lars Martin Sandvik; Kildemo, Morten; Lindgren, Mikael

2010-01-01

276

Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging  

Energy Technology Data Exchange (ETDEWEB)

The application of time-resolved fluorescence spectroscopy (TRFS) to in vivo tissue diagnosis requires a method for fast acquisition of fluorescence decay profiles in multiple spectral bands. This study focusses on development of a clinically compatible fiber-optic based multispectral TRFS (ms-TRFS) system together with validation of its accuracy and precision for fluorescence lifetime measurements. It also presents the expansion of this technique into an imaging spectroscopy method. A tandem array of dichroic beamsplitters and filters was used to record TRFS decay profiles at four distinct spectral bands where biological tissue typically presents fluorescence emission maxima, namely, 390, 452, 542, and 629 nm. Each emission channel was temporally separated by using transmission delays through 200 ?m diameter multimode optical fibers of 1, 10, 19, and 28 m lengths. A Laguerre-expansion deconvolution algorithm was used to compensate for modal dispersion inherent to large diameter optical fibers and the finite bandwidth of detectors and digitizers. The system was found to be highly efficient and fast requiring a few nano-Joule of laser pulse energy and <1 ms per point measurement, respectively, for the detection of tissue autofluorescent components. Organic and biological chromophores with lifetimes that spanned a 0.8–7 ns range were used for system validation, and the measured lifetimes from the organic fluorophores deviated by less than 10% from values reported in the literature. Multi-spectral lifetime images of organic dye solutions contained in glass capillary tubes were recorded by raster scanning the single fiber probe in a 2D plane to validate the system as an imaging tool. The lifetime measurement variability was measured indicating that the system provides reproducible results with a standard deviation smaller than 50 ps. The ms-TRFS is a compact apparatus that makes possible the fast, accurate, and precise multispectral time-resolved fluorescence lifetime measurements of low quantum efficiency sub-nanosecond fluorophores.

Yankelevich, Diego R. [Department of Electrical and Computer Engineering, University of California, 3101 Kemper Hall, Davis, California 95616 (United States); Department of Biomedical Engineering, University of California, 451 Health Sciences Drive, Davis, California 95616 (United States); Ma, Dinglong; Liu, Jing; Sun, Yang; Sun, Yinghua; Bec, Julien; Marcu, Laura, E-mail: lmarcu@ucdavis.edu [Department of Biomedical Engineering, University of California, 451 Health Sciences Drive, Davis, California 95616 (United States); Elson, Daniel S. [Hamlyn Centre for Robotic Surgery, Department of Surgery and Cancer, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom)

2014-03-15

277

Physiotherapy Exercise After Fast-Track Total Hip and Knee Arthroplasty: Time for Reconsideration?  

DEFF Research Database (Denmark)

Bandholm T, Kehlet H. Physiotherapy exercise after fast-track total hip and knee arthroplasty: time for reconsideration? Major surgery, including total hip arthroplasty (THA) and total knee arthroplasty (TKA), is followed by a convalescence period, during which the loss of muscle strength and function is considerable, especially early after surgery. In recent years, a combination of unimodal evidence-based perioperative care components has been demonstrated to enhance recovery, with decreased need for hospitalization, convalescence, and risk of medical complications after major surgery-the fast-track methodology or enhanced recovery programs. It is the nature of this methodology to systematically and scientifically optimize all perioperative care components, with the overall goal of enhancing recovery. This is also the case for the care component "physiotherapy exercise" after THA and TKA. The 2 latest meta-analyses on the effectiveness of physiotherapy exercise after THA and TKA generally conclude that physiotherapy exercise after THA and TKA either does not work or is not very effective. The reason for this may be that the "pill" of physiotherapy exercise typically offered after THA and TKA does not contain the right active ingredients (too little intensity) or is offered at the wrong time (too late after surgery). We propose changing the focus to earlier initiated and more intensive physiotherapy exercise after THA and TKA (fast-track physiotherapy exercise), to reduce the early loss of muscle strength and function after surgery. Ideally, the physiotherapy exercise interventions after THA and TKA should be simple, using few and well-chosen exercises that are described in detail, adhering to basic exercise physiology principles, if possible.

Bandholm, Thomas; Kehlet, Henrik

2012-01-01

278

Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging  

International Nuclear Information System (INIS)

The application of time-resolved fluorescence spectroscopy (TRFS) to in vivo tissue diagnosis requires a method for fast acquisition of fluorescence decay profiles in multiple spectral bands. This study focusses on development of a clinically compatible fiber-optic based multispectral TRFS (ms-TRFS) system together with validation of its accuracy and precision for fluorescence lifetime measurements. It also presents the expansion of this technique into an imaging spectroscopy method. A tandem array of dichroic beamsplitters and filters was used to record TRFS decay profiles at four distinct spectral bands where biological tissue typically presents fluorescence emission maxima, namely, 390, 452, 542, and 629 nm. Each emission channel was temporally separated by using transmission delays through 200 ?m diameter multimode optical fibers of 1, 10, 19, and 28 m lengths. A Laguerre-expansion deconvolution algorithm was used to compensate for modal dispersion inherent to large diameter optical fibers and the finite bandwidth of detectors and digitizers. The system was found to be highly efficient and fast requiring a few nano-Joule of laser pulse energy and <1 ms per point measurement, respectively, for the detection of tissue autofluorescent components. Organic and biological chromophores with lifetimes that spanned a 0.8–7 ns range were used for system validation, and the measured lifetimes from the organic fluorophores deviated by less than 10% from values reported in the literature. Multi-spectral lifetime images of organic dye solutions contained in glass capillary tubes were recorded by raster scanning the single fiber probe in a 2D plane to validate the system as an imaging tool. The lifetime measurement variability was measured indicating that the system provides reproducible results with a standard deviation smaller than 50 ps. The ms-TRFS is a compact apparatus that makes possible the fast, accurate, and precise multispectral time-resolved fluorescence lifetime measurements of low quantum efficiency sub-nanosecond fluorophores

279

A Correlation-based Timing Calibration and Diagnostic Technique for Fast Digitizing ASICs  

Science.gov (United States)

A general procedure for precision timing calibration of waveform digitizing systems is presented. Application speci?c integrated circuits (ASICs) implementing this functionality are increasingly used in high-energy physics as replacements for stand-alone time-to-digital and analog-to-digital modules. However, process variations cause such ASICs to have irregularly spaced timing intervals between samples, so careful calibration is required to improve the timing resolution of such systems. The procedure presented here exploits correlations between nearby samples of a sine wave of known frequency to obtain the time difference between them. As only the correlations are used, the procedure can be performed without knowledge of the phase of the input signal, and converges with smaller data samples than other common techniques. It also serves as a valuable diagnostic tool, allowing a fast, visual, qualitative check of gain mismatches between sampling cells and other ADC artifacts. Work is continuing to extend the procedure to ?t for timing intervals in the face of such non-idealities. We present both the algorithm and example calibration results from a commercial oscilloscope and the PSEC-3 ASIC. For the latter, we have also applied the calibration to improve timing resolution in the readout of a prototype microchannel plate photomultiplier tube with a stripline anode con?guration.

Nishimura, Kurtis; Romero-Wolf, Andrés; the Large Area Picosecond Photodetector Collaboration [1

280

Time and space resolved interferometry for laser-generated fast electron measurements  

International Nuclear Information System (INIS)

A technique developed to measure in time and space the dynamics of the electron populations resulting from the irradiation of thin solids by ultraintense lasers is presented. It is a phase reflectometry technique that uses an optical probe beam reflecting off the target rear surface. The phase of the probe beam is sensitive to both laser-produced fast electrons of low-density streaming into vacuum and warm solid density electrons that are heated by the fast electrons. A time and space resolved interferometer allows to recover the phase of the probe beam sampling the target. The entire diagnostic is computationally modeled by calculating the probe beam phase when propagating through plasma density profiles originating from numerical calculations of plasma expansion. Matching the modeling to the experimental measurements allows retrieving the initial electron density and temperature of both populations locally at the target surface with very high temporal and spatial resolution (?4 ps,6 ?m). Limitations and approximations of the diagnostic are discussed and analyzed.

 
 
 
 
281

Time-Space Decoupled Explicit Method for Fast Numerical Simulation of Tsunami Propagation  

Science.gov (United States)

This study presents a novel explicit numerical scheme for simulating tsunami propagation using the exact solution of the wave equations. The objective of this study is to develop a fast and stable numerical scheme by decoupling the wave equation in both the time and space domains. First, the finite difference scheme of the shallow-water equations for tsunami simulation are briefly introduced. The time-space decoupled explicit method based on the exact solution of the wave equation is given for the simulation of tsunami propagation without including frequency dispersive effects. Then, to consider wave dispersion, the second-order accurate numerical scheme to solve the shallow-water equations, which mimics the physical frequency dispersion with numerical dispersion, is derived. Lastly, the computation efficiency and the accuracy of the two types of numerical schemes are investigated by the 2004 Indonesia tsunami and the solution of the Boussinesq equation for a tsunami with Gaussian hump over both uniform and varying water depths. The simulation results indicate that the proposed numerical scheme can achieve a fast and stable tsunami propagation simulation while maintaining computation accuracy.

Guo, Anxin; Xiao, Shengchao; Li, Hui

2014-05-01

282

The Effect of Holly Fasting Month of Ramadan on the Delayed Type Hypersensitivity Response to Purified Protein Derivative  

Directory of Open Access Journals (Sweden)

Full Text Available Studies during recent decade indicate that low calorie intake has potentiating effect on immune response . So the effect of fasting in holly month of Ramadan on cellular immune was studied. In this study , delayed type hypersensitivity (DTH to purified protein derivative (PPD test was selected to evaluate cellular immune response , because this test is not only very simple but also is valuable and reliable. This research studied DTH to PPD in two groups of students before and after the holly fasting month of Ramadan. The range of age in the both groups was 20-30 year. Mantoux method was the selected method to evaluate DTH response to PPD. DTH response to PPD in fasting group increased from 8.8 to 13 mm , which is statistically significant (P<0.05. It is noticeable that the differences between the rates of increasing DTH response to PPD in control group and fasting group was statistically significant (P<0.05. Based on the above finding it can be concluded that fasting has potentiating effect on cellular immune response.

M. Rahmani

2003-04-01

283

A 3 A sink/source current fast transient response low-dropout Gm driven linear regulator  

Science.gov (United States)

A 3 A sink/source Gm-driven CMOS low-dropout regulator (LDO), specially designed for low input voltage and low cost, is presented by utilizing the structure of a current mirror Gm (transconductance) driving technique, which provides high stability as well as a fast load transient response. The proposed LDO was fabricated by a 0.5 ?m standard CMOS process, and the die size is as small as 1.0 mm2. The proposed LDO dissipates 220 ?A of quiescent current in no-load conditions and is able to deliver up to 3 A of load current. The measured results show that the output voltage can be resumed within 2 ?s with a less than 1 mV overshoot and undershoot in the output current step from -1.8 to 1.8 A with a 0.1 ?s rising and falling time at three 10 ?F ceramic capacitors.

Xiuqin, Chu; Qingwei, Li; Xinquan, Lai; Bing, Yuan; Yanming, Li; Yongrui, Zhao

2011-06-01

284

A 3 A sink/source current fast transient response low-dropout Gm driven linear regulator  

International Nuclear Information System (INIS)

A 3 A sink/source Gm-driven CMOS low-dropout regulator (LDO), specially designed for low input voltage and low cost, is presented by utilizing the structure of a current mirror Gm (transconductance) driving technique, which provides high stability as well as a fast load transient response. The proposed LDO was fabricated by a 0.5 ?m standard CMOS process, and the die size is as small as 1.0 mm2. The proposed LDO dissipates 220 ?A of quiescent current in no-load conditions and is able to deliver up to 3 A of load current. The measured results show that the output voltage can be resumed within 2 ?s with a less than 1 mV overshoot and undershoot in the output current step from -1.8 to 1.8 A with a 0.1 ?s rising and falling time at three 10 ?F ceramic capacitors. (semiconductor integrated circuits)

285

Target Localization by Resolving the Time Synchronization Problem in Bistatic Radar Systems Using Space Fast-Time Adaptive Processor  

Directory of Open Access Journals (Sweden)

Full Text Available The proposed technique allows the radar receiver to accurately estimate the range of a large number of targets using a transmitter of opportunity as long as the location of the transmitter is known. The technique does not depend on the use of communication satellites or GPS systems, instead it relies on the availability of the direct transmit copy of the signal from the transmitter and the reflected paths off the various targets. An array-based space-fast time adaptive processor is implemented in order to estimate the path difference between the direct signal and the delayed signal, which bounces off the target. This procedure allows us to estimate the target distance as well as bearing.

D. Madurasinghe

2009-01-01

286

Linking Response-Time Parameters onto a Common Scale  

Science.gov (United States)

Although response times on test items are recorded on a natural scale, the scale for some of the parameters in the lognormal response-time model (van der Linden, 2006) is not fixed. As a result, when the model is used to periodically calibrate new items in a testing program, the parameter are not automatically mapped onto a common scale. Several…

van der Linden, Wim J.

2010-01-01

287

Equilibrium free energies from fast-switching trajectories with large time steps  

CERN Document Server

Jarzynski's identity for the free energy difference between two equilibrium states can be viewed as a special case of a more general procedure based on phase space mappings. Solving a system's equation of motion by approximate means generates a mapping that is perfectly valid for this purpose, regardless of how closely the solution mimics true time evolution. We exploit this fact, using crudely dynamical trajectories to compute free energy differences that are in principle exact. Numerical simulations show that Newton's equation can be discretized to low order over very large time steps (limited only by the computer's ability to represent resulting values of dynamical variables) without sacrificing thermodynamic accuracy. For computing the reversible work required to move a particle through a dense liquid, these calculations are more efficient than conventional fast switching simulations by more than an order of magnitude. We also explore consequences of the phase space mapping perspective for systems at equi...

Lechner, W; Dellago, C; Geissler, Phillip L; Lechner, Wolfgang; Oberhofer, Harald; Dellago, Christoph; Geissler, Phillip L.

2005-01-01

288

Comparisons of Crosswind Velocity Profile Estimates Used in Fast-Time Wake Vortex Prediction Models  

Science.gov (United States)

Five methods for estimating crosswind profiles used in fast-time wake vortex prediction models are compared in this study. Previous investigations have shown that temporal and spatial variations in the crosswind vertical profile have a large impact on the transport and time evolution of the trailing vortex pair. The most important crosswind parameters are the magnitude of the crosswind and the gradient in the crosswind shear. It is known that pulsed and continuous wave lidar measurements can provide good estimates of the wind profile in the vicinity of airports. In this study comparisons are made between estimates of the crosswind profiles from a priori information on the trajectory of the vortex pair as well as crosswind profiles derived from different sensors and a regional numerical weather prediction model.

Pruis, Mathew J.; Delisi, Donald P.; Ahmad, Nashat N.

2011-01-01

289

Design and calibration of a fast-time resolution charge exchange analyzer  

International Nuclear Information System (INIS)

A five channel, fast time resolution, scanning charge exchange analyzer has been developed for the Madison Symmetric Torus (MST). The analyzer consists of an iron vacuum vessel, a gas stripping cell, an electrostatic bending field, and five continuous electron multiplier detectors. The incident neutral flux and operation of the detectors in current mode limits the time resolution of the analyzer to 10 ?s. The analyzer was absolutely calibrated over the energy range of interest (500--2000 eV) with an H+ beam, so that the charge exchange power loss could also be measured. The analyzer can be swiveled on a shot-to-shot basis for measurements of Ti(r), where 0.3 < r/a < 0.7. The mechanical design was driven by the need for a low cost, expandable ion temperature diagnostic

290

Organic scintillators response function modeling for Monte Carlo simulation of Time-of-Flight measurements.  

Science.gov (United States)

In neutron Time-of-Flight (TOF) measurements performed with fast organic scintillation detectors, both pulse arrival time and amplitude are relevant. Monte Carlo simulation can be used to calculate the time-energy dependant neutron flux at the detector position. To convert the flux into a pulse height spectrum, one must calculate the detector response function for mono-energetic neutrons. MCNP can be used to design TOF systems, but standard MCNP versions cannot reliably calculate the energy deposited by fast neutrons in the detector since multiple scattering effects must be taken into account in an analog way, the individual recoil particles energy deposit being summed with the appropriate scintillation efficiency. In this paper, the energy response function of 2?×2? and 5?×5? liquid scintillation BC-501 A (Bicron) detectors to fast neutrons ranging from 20 keV to 5.0 MeV is computed with GEANT4 to be coupled with MCNPX through the "MCNP Output Data Analysis" software developed under ROOT (Carasco, 2010). PMID:22100378

Carasco, C

2012-07-01

291

A Statistical Approach to Response-Time Analysis of Complex Real-Time Embedded Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents RapidRT, a novel statistical approach to Worst-Case Response-Time (WCRT) analysis targeting complex embedded real-time systems. The proposed algorithm combines Extreme Value Theory (EVT) and other statistical methods in order to produce a probabilistic WCRT estimate. This estimate is calculated using response time data from either Monte Carlo simulations of a detailed model of the system, or from response-time measurements of the real system. The method could be considered...

Lu, Yue; Nolte, Thomas; Kraft, Johan; Norstro?m, Christer

2010-01-01

292

Fast-response magnet coil system for controlling plasma equilibrium in a tokamak with a strong magnetic field  

International Nuclear Information System (INIS)

Two special fast-control coils are used to provide stability of a plasma filament in a horizontal plane of a tokamak with a strong magnetic field. According to the fast-response conditions satisfying the control system, power of the supply system for these coils is to constitute 35 MW (U=2.5 kV, I=14 kA). A basic circuit of the supply system with a capacitor is given, the circuit consists of a capacitor bank with a rectifier providing for a preliminary chage of a capacitor bank, thyristor switches, a shut-down system, circuit breakers, valve devices. A basic circuit of supply system for plasma equilibrium coil built on the base of fast-response and reliability priciples is presented. Fast voltage removal is provided by shorting out a c

293

Fast nonlinear optical response from proton-bombarded multiple quantum well structures  

Energy Technology Data Exchange (ETDEWEB)

Proton bombardment is shown to shorten the recovery time of the excitonic absorption in GaAs/GaAlAs multiple quantum well saturable absorbers. The response time can be reduced from 30 ns to 150 ps without affecting the absorption characteristics or the saturation energy.

Silberberg, Y.; Smith, P.W.; Miller, D.A.B.; Tell, B.; Gossard, A.C.; Wiegmann, W.

1985-04-15

294

Fast nonlinear optical response from proton-bombarded multiple quantum well structures  

International Nuclear Information System (INIS)

Proton bombardment is shown to shorten the recovery time of the excitonic absorption in GaAs/GaAlAs multiple quantum well saturable absorbers. The response time can be reduced from 30 ns to 150 ps without affecting the absorption characteristics or the saturation energy

295

The temporal pattern of cfos activation in hypothalamic, cortical, and brainstem nuclei in response to fasting and refeeding in male mice.  

Science.gov (United States)

In this study we examined fasted and refed cfos activation in cortical, brainstem, and hypothalamic brain regions associated with appetite regulation. We examined a number of time points during refeeding to gain insight into the temporal pattern of neuronal activation and changes in endocrine parameters associated with fasting and refeeding. In response to refeeding, blood glucose and plasma insulin returned to basal levels within 30 minutes, whereas plasma nonesterified fatty acids and leptin returned to basal levels after 1 and 2 hours, respectively. Within the hypothalamic arcuate nucleus (ARC), fasting increased cfos activation in ?25% of neuropeptide Y neurons, which was terminated 1 hour after refeeding. Fasting had no effect on cfos activation in pro-opiomelanocortin neurons; however, 1 and 2 hours of refeeding significantly activated ?20% of ARC pro-opiomelanocortin neurons. Acute refeeding (30, 60, and 120 minutes), but not fasting, increased cfos activation in the nucleus accumbens, the cingulate cortex (but not the insular cortex), the medial and lateral parabrachial nucleus, the nucleus of the solitary tract, the area postrema, the dorsal raphe, and the ventromedial nucleus of the hypothalamus. After 6 hours of refeeding, cfos activity was reduced in the majority of these regions compared with that at earlier time points. Our data indicate that acute refeeding, rather than long-term fasting, activates cortical, brainstem, and hypothalamic neural circuits associated with appetite regulation and reward processing. Although the hypothalamic ARC remains a critical sensory node detecting changes in the metabolic state and feedback during fasting and acute refeeding, our results also reveal the temporal pattern in cfos activation in cortical and brainstem areas implicated in the control of appetite and body weight regulation. PMID:24424063

Wu, Qunli; Lemus, Moyra B; Stark, Romana; Bayliss, Jacqueline A; Reichenbach, Alex; Lockie, Sarah H; Andrews, Zane B

2014-03-01

296

A fast density-based clustering algorithm for real-time Internet of Things stream.  

Science.gov (United States)

Data streams are continuously generated over time from Internet of Things (IoT) devices. The faster all of this data is analyzed, its hidden trends and patterns discovered, and new strategies created, the faster action can be taken, creating greater value for organizations. Density-based method is a prominent class in clustering data streams. It has the ability to detect arbitrary shape clusters, to handle outlier, and it does not need the number of clusters in advance. Therefore, density-based clustering algorithm is a proper choice for clustering IoT streams. Recently, several density-based algorithms have been proposed for clustering data streams. However, density-based clustering in limited time is still a challenging issue. In this paper, we propose a density-based clustering algorithm for IoT streams. The method has fast processing time to be applicable in real-time application of IoT devices. Experimental results show that the proposed approach obtains high quality results with low computation time on real and synthetic datasets. PMID:25110753

Amini, Amineh; Saboohi, Hadi; Wah, Teh Ying; Herawan, Tutut

2014-01-01

297

Time-resolved fast-neutron pinhole camera for studying thermonuclear plasmas  

International Nuclear Information System (INIS)

A fast-neutron pinhole camera with high detection efficiency and nanosecond time-resolution has been developed and applied to the investigation of the spatial and temporal distributions of DD- and DT-neutrons produced by thermonuclear plasmas. The pinhole consists of a specially designed 1.15 m long copper collimator with an effective aperture of 1 mm diameter. Several different types of spatial resolution detectors have been used at the image plane: (1) a multi-element, scintillation-photomultiplier system used for time-resolved measurements consisting of sixty-one individual detectors, (2) a scintillation-fiber-chamber coupled to a gated image-intensifier tube used for direct photographing of the neutron image, and (3) a propane bubble chamber used for time-integrated recording with a capability to distinguish DD- from DT-neutrons. Pulsed neutron sources with typical dimensions of 1 cm emitting of the order of 1012 neutrons over a time period of 10-100 nsec have been investigated. A spatial resolution of 1 mm and a time resolution of approximately 10 nsec was achieved in the investigations of dense plasma compression phenomena

298

Time-resolved fast-neutron pinhole camera for studying thermonuclear plasmas  

Energy Technology Data Exchange (ETDEWEB)

A fast-neutron pinhole camera with high detection efficiency and nanosecond time-resolution has been developed and applied to the investigation of the spatial and temporal distributions of DD- and DT-neutrons produced by thermonuclear plasmas. The pinhole consists of a specially designed 1.15 m long copper collimator with an effective aperture of 1 mm diameter. Several different types of spatial resolution detectors have been used at the image plane: (1) a multi-element, scintillation-photomultiplier system used for time-resolved measurements consisting of sixty-one individual detectors, (2) a scintillation-fiber-chamber coupled to a gated image-intensifier tube used for direct photographing of the neutron image, and (3) a propane bubble chamber used for time-integrated recording with a capability to distinguish DD- from DT-neutrons. Pulsed neutron sources with typical dimensions of 1 cm emitting of the order of 10/sup 12/ neutrons over a time period of 10-100 nsec have been investigated. A spatial resolution of 1 mm and a time resolution of approximately 10 nsec was achieved in the investigations of dense plasma compression phenomena.

Bauer, R.W.; Weingart, R.C.

1976-02-02

299

Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing  

Science.gov (United States)

In the framework of the construction of the double time-of-flight spectrometer VERDI, where we aim at measuring pre- and post-neutron masses directly and simultaneously, ultra-fast time pick-up detectors based on artificial diamond material were investigated for the first time with fission fragments from 252Cf (0.5 MeV/uneutrons/cm2 and 3×1010?-particles/cm2. This fluence is characteristic for fission experiments. The pre-requisite for the observed signal stability is the application of priming of the diamond material with a strong ?-source for about 48 h. The intrinsic timing resolution of a 100 ?m thick polycrystalline CVD diamond detector with a size of 1×1 cm2 was determined to ?int=(283±41) ps by comparison with Monte-Carlo simulations. Using broadband pre-amplifiers, 4-fold segmented detectors of same total size and with a thickness of 180 ?m show an intrinsic timing resolution of ?int=(106±21) ps. This is highly competitive with the best micro-channel plate detectors. Due to the limited and batch-dependent charge collection efficiency of poly-crystalline diamond material, the detection efficiency for fission fragments may be smaller than 100%.

Oberstedt, S.; Borcea, R.; Bry?, T.; Gamboni, Th.; Geerts, W.; Hambsch, F.-J.; Oberstedt, A.; Vidali, M.

2013-06-01

300

Fault Diagnosis of Ball Bearing using Time Domain Analysis and Fast Fourier Transformation  

Directory of Open Access Journals (Sweden)

Full Text Available In this study Fault diagnosis of Ball bearings is done by statistical analysis under various time domain parameters. The objective of this study is to investigate the correlation between time domain and frequency domain analysis of vibration signature to judge and find the fault in bearing. This is achieved by vibration analysis and investigating different time domain parameter like Kurtosis, Skewness, Crest factor, RMS Value. For this purpose the bearing is coupled to the motor and observation were taken at 810 rpm. Vibration of the bearing are converted in voltage signal (milivolt using an accelerometer/piezoelectric transducer. The bearing is taken under two different conditions viz Healthy (normal bearing and Faulty (defected outer race bearing with the aim of fault detection. Vibration data of healthy bearing are used as a standard for the analysis of vibration spectra of faulty bearing. Vibration signals are analyzed through different operations performed in MATLAB software. The result shows that the statistical analysis through different time domain parameters and its fast Fourier transformation provides efficient representation of fault detection in rolling element bearings. So as an initial stage if we find kurtosis and skewness values it can predict a fault. And if we get higher values of time domain parameters then only it needs to go for its frequency domain analysis. In this paper we also get exact fault position for defective bearing by its frequency domain analysis.

Pravesh Durkhure*1

2014-07-01

 
 
 
 
301

Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging  

Science.gov (United States)

The application of time-resolved fluorescence spectroscopy (TRFS) to in vivo tissue diagnosis requires a method for fast acquisition of fluorescence decay profiles in multiple spectral bands. This study focusses on development of a clinically compatible fiber-optic based multispectral TRFS (ms-TRFS) system together with validation of its accuracy and precision for fluorescence lifetime measurements. It also presents the expansion of this technique into an imaging spectroscopy method. A tandem array of dichroic beamsplitters and filters was used to record TRFS decay profiles at four distinct spectral bands where biological tissue typically presents fluorescence emission maxima, namely, 390, 452, 542, and 629 nm. Each emission channel was temporally separated by using transmission delays through 200 ?m diameter multimode optical fibers of 1, 10, 19, and 28 m lengths. A Laguerre-expansion deconvolution algorithm was used to compensate for modal dispersion inherent to large diameter optical fibers and the finite bandwidth of detectors and digitizers. The system was found to be highly efficient and fast requiring a few nano-Joule of laser pulse energy and sub-nanosecond fluorophores.

Yankelevich, Diego R.; Ma, Dinglong; Liu, Jing; Sun, Yang; Sun, Yinghua; Bec, Julien; Elson, Daniel S.; Marcu, Laura

2014-03-01

302

Signal and Noise Analysis in TRION -Time-Resolved Integrative Optical Fast Neutron Detector  

CERN Document Server

TRION is a sub-mm spatial resolution fast neutron imaging detector, which employs an integrative optical time-of-flight technique. The detector was developed for fast neutron resonance radiography, a method capable of detecting a broad range of conventional and improvised explosives. In this study we have analyzed in detail, using Monte-Carlo calculations and experimentally determined parameters, all the processes that influence the signal and noise in the TRION detector. In contrast to event-counting detectors where the signal-to-noise ratio is dependent only on the number of detected events (quantum noise), in an energy-integrating detector additional factors, such as the fluctuations in imparted energy, number of photoelectrons, system gain and other factors will contribute to the noise. The excess noise factor (over the quantum noise) due to these processes was 4.3, 2.7, 2.1, 1.9 and 1.9 for incident neutron energies of 2, 4, 7.5, 10 and 14 MeV, respectively. It is shown that, even under ideal light colle...

Vartsky, D; Mor, I; Goldberg, M B; Bar, D; Dangendorf, V

2009-01-01

303

Model for Predicting End User Web Page Response Time  

CERN Document Server

Perceived responsiveness of a web page is one of the most important and least understood metrics of web page design, and is critical for attracting and maintaining a large audience. Web pages can be designed to meet performance SLAs early in the product lifecycle if there is a way to predict the apparent responsiveness of a particular page layout. Response time of a web page is largely influenced by page layout and various network characteristics. Since the network characteristics vary widely from country to country, accurately modeling and predicting the perceived responsiveness of a web page from the end user's perspective has traditionally proven very difficult. We propose a model for predicting end user web page response time based on web page, network, browser download and browser rendering characteristics. We start by understanding the key parameters that affect perceived response time. We then model each of these parameters individually using experimental tests and statistical techniques. Finally, we d...

Nagarajan, Sathya Narayanan

2012-01-01

304

Fast-response power supply of magnet coils for plasma equilibrium control in tokamak devices  

International Nuclear Information System (INIS)

Various power supply systems for plasma equilibrium control coils in tokamak-devices have been analyzed. Power supply systems which use inductive and capacitor storages are considered. Advantages of the latter are shown. Description of a system for the T-15 tokamak is presented, its parameters being as follows: power source voltage is 2.5 kV, nominal current equals 6 kA, maximum switch-off current - 8 kA. A capacitor bank for the energy of 5x106 J and voltage 2.8 kV is used as a power supply source. Thyristor keys with water cooling on the basis of fast-response thyristors of the TV-400-8 type are developed. Each key consists of 90 thyristors. Total number of the keys in the system equals 16

305

Fast response neutron emission monitor for fusion reactor using stilbene scintillator and Flash-ADC.  

Science.gov (United States)

The stilbene neutron detector which has been used for neutron emission profile monitoring in JT-60U has been improved, to respond to the requirement to observe the high-frequency phenomena in megahertz region such as toroidicity-induced Alfvén Eigen mode in burning plasma as well as the spatial profile and the energy spectrum. This high-frequency phenomenon is of great interest and one of the key issues in plasma physics in recent years. To achieve a fast response in the stilbene detector, a Flash-ADC is applied and the wave form of the anode signal stored directly, and neutron/gamma discrimination was carried out via software with a new scheme for data acquisition mode to extend the count rate limit to MHz region from 1.3 x 10(5) neutron/s in the past, and confirmed the adequacy of the method. PMID:17517674

Itoga, T; Ishikawa, M; Baba, M; Okuji, T; Oishi, T; Nakhostin, M; Nishitani, T

2007-01-01

306

Fast Response to Infection Spread and Cyber Attacks on Large-Scale Networks  

CERN Document Server

We present a strategy for designing fast methods of response to cyber attacks and infection spread on complex weighted networks. In these networks, nodes can be interpreted as primitive elements of the system, and weighted edges reflect the strength of interaction among these elements. The proposed strategy belongs to the family of multiscale methods whose goal is to approximate the system at multiple scales of coarseness and to obtain a solution of microscopic scale by combining the information from coarse scales. In recent years these methods have demonstrated their potential for solving optimization and analysis problems on large-scale networks. We consider an optimization problem that is based on the SIS epidemiological model. The objective is to detect the network nodes that have to be immunized in order to keep a low level of infection in the system.

Leyffer, Sven

2012-01-01

307

Temporal response and real time measurements with 5GHz photocell-oscilloscope system at low light levels  

International Nuclear Information System (INIS)

Experiments were carried out to investigate by means of picosecond mode-locked laser pulses the performance of fast vacuum photoelectric cells associated with a high sensitivity and high speed cathode-ray tube provided with a channel plate electron multiplier. With an amplitude sensitivity of 140mV/cm an overall time of response of less than 100 ps was measured

308

A fast-response production-inventory model for deteriorating seasonal products with learning in set-ups  

Directory of Open Access Journals (Sweden)

Full Text Available The classical production-inventory model assumes that both demand and set-up costs are constant. However, in real manufacturing environment, managers usually embark on continuous improvement programmes that often lead to more effective use of tools and machineries and consequently reduction in set-up costs. In fact, constant emphasis on reduction of set-up costs is usually cited as one of the factors responsible for the efficiency of Japanese manufacturing methods. On the other hand, the demand for seasonal product is often characterized by a mixture of time-dependent patterns over the entire season. This paper investigates the effect of learning-based reduction in set-up costs on the optimal schedules and costs of a production-inventory system for deteriorating seasonal products. The demand pattern is a general three-phase ramp-type demand function that represents the various phases of demand commonly observed in many seasonal products in the market. A two-parameter Weibull-distribution function is used for the deterioration of items in order to make the model more generalized and realistic. The study further presents two different multi-period production strategies that can ensure a fast-response to customers’ demand and compare them with the usual single period strategy. The Numerical example and sensitivity analysis shows that learning-based reduction in set-up costs leads to higher production frequency and shorter production runs which are vital aspects of the just-in-time (JIT philosophy.

Ibraheem Abdul

2011-10-01

309

Fast Frequency Response Capability of Photovoltaic Power Plants: The Necessity of New Grid Requirements and Definitions  

Directory of Open Access Journals (Sweden)

Full Text Available In recent years, only a small number of publications have been presented addressing power system stability with the increased use of large-scale photovoltaic (PV generation around the world. The focus of these publications was on classical stability problems, such as transient and small signal stability, without considering frequency stability. Nevertheless, with increased PV generation, its effects on system frequency response during contingencies can no longer be ignored, especially in the case of weakly interconnected networks or isolated power systems. This paper addresses the impacts of large scale PV generation on the frequency stability of power systems. The positive effects of deloaded PV power plants (PV-PPs able to support system frequency recovery during the initial seconds after major contingencies are also examined. Because this type of frequency support is not covered by current definitions, a new terminology is proposed that includes the frequency response of inertia-less generation units immediately after major power imbalances. We refer to this type of frequency support as fast frequency response (FFR. Finally, a discussion is also presented regarding the applicability and pertinence of frequency-related grid requirements for PV-PPs in the case of real power systems. The investigation is based on the isolated power system of northern Chile. The obtained results indicate that in the case of major power imbalances, no significant effects arise on the system frequency response until PV penetration levels exceed approximately 20%. From a system security perspective, the problems arise for PV penetration levels of approximately 50%, in which case, the frequency response capability in PV-PPs would be justified during certain hours of the year.

Claudia Rahmann

2014-09-01

310

Response Analysis Survey: A Qualitative Look at Response and Nonresponse in the American Time Use Survey.  

Science.gov (United States)

In January 2004, the Bureau of Labor Statistics (BLS) conducted a Response Analysis Survey (RAS) that elicited qualitative information related to survey response in the American Time Use Survey (ATUS.) This information was elicited from both respondents a...

G. E. O'Neill, J. R. Sincavage

2008-01-01

311

Modeling of the Response Time of Thermal Flow Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available This paper introduces a simple theoretical model for the response time of thermal flow sensors. Response time is defined here as the time needed by the sensor output signal to reach 63.2% of amplitude due to a change of fluid flow. This model uses the finite-difference method to solve the heat transfer equations, taking into consideration the transient conduction and convection between the sensor membrane and the surrounding fluid. Program results agree with experimental measurements and explain the response time dependence on the velocity and the sensor geometry. Values of the response time vary from about 5 ms in the case of stagnant flow to 1.5 ms for a flow velocity of 44 m/s.

Walter Lang

2011-10-01

312

Improvement in the gamma-ray timing measurements using a fast digital oscilloscope  

International Nuclear Information System (INIS)

The time resolutions of a new positron lifetime spectrometer based on a fast digital oscilloscope are measured using BaF2 and plastic (BC-422) scintillators. It is found that the plastic scintillator has only a small advantage in the time resolution compared to BaF2. For the cascade decay of 60Co (1.17 and 1.33 MeV), the time resolution for a pair of BC-422 plastic scintillators having a size of 40 mm in diameter and 20 mm thick is about 120 ps FWHM. This value is very close to that of BaF2. Although a time resolution of 90 ps FWHM is obtained using a pair of small BC-422 plastic scintillators (30 mm in diameter, 10 mm thick), the counting rate is nearly two orders of magnitude lower than that with BaF2. It is thus concluded that the BaF2 is the best scintillator at present for the practical positron lifetime spectroscopy

313

Program for the analysis of time series. [by means of fast Fourier transform algorithm  

Science.gov (United States)

A digital computer program for the Fourier analysis of discrete time data is described. The program was designed to handle multiple channels of digitized data on general purpose computer systems. It is written, primarily, in a version of FORTRAN 2 currently in use on CDC 6000 series computers. Some small portions are written in CDC COMPASS, an assembler level code. However, functional descriptions of these portions are provided so that the program may be adapted for use on any facility possessing a FORTRAN compiler and random-access capability. Properly formatted digital data are windowed and analyzed by means of a fast Fourier transform algorithm to generate the following functions: (1) auto and/or cross power spectra, (2) autocorrelations and/or cross correlations, (3) Fourier coefficients, (4) coherence functions, (5) transfer functions, and (6) histograms.

Brown, T. J.; Brown, C. G.; Hardin, J. C.

1974-01-01

314

Fast Tracker: A Hardware Real Time Track Finder for the ATLAS Trigger System  

CERN Document Server

The Fast Tracker (FTK) is an integral part of the trigger upgrade program for the ATLAS detector at the Large Hadron Collider (LHC). As the LHC luminosity approaches its design level of 10^34cm^?2s^?1, the combinatorial problem posed by charged particle tracking becomes increasingly difficult due to the swelling of multiple interactions per bunch crossing (pile-up). The FTK is a highly-parallel hardware system intended to provide high-quality tracks with transverse momentum above 1 GeV/c in real time for online trigger system. The FTK system’s design, based on a mixture of advanced technologies, and expected physics performance will be presented.

Kimura, N; The ATLAS collaboration

2013-01-01

315

The first synchrotron infrared beamlines at the Advanced Light Source: Microspectroscopy and fast timing  

International Nuclear Information System (INIS)

A set of new infrared (IR) beamlines on the 1.4 bending magnet port at the Advanced Light Source, LBNL, are described. Using a synchrotron as an IR source provides considerable brightness advantages, which manifests itself most beneficially when performing spectroscopy on a microscopic length scale. Beamline (BL) 1.4.3 is a dedicated microspectroscopy beamline, where the much smaller focused spot size using the synchrotron source is utilized. This enables an entirely new set of experiments to be performed where spectroscopy on a truly microscopic scale is now possible. BL 1.4.2 consists of a vacuum FTIR bench with a wide spectral range and step-scan capabilities. The fast timing is demonstrated by observing the synchrotron electron storage pattern at the ALS

316

Single-crystal diamond detector for time-resolved measurements of a pulsed fast-neutron beam  

Science.gov (United States)

A fast-neutron detector for time-resolved beam measurements at spallation neutron sources is presented. The device features a p-type/intrinsic/metal Schottky barrier structure where the active (intrinsic) detection layer is a 150 ?m thick single-crystal diamond obtained by chemical-vapour deposition. Coupling to fast front-end electronics preserves the excellent timing properties of the device as demonstrated in tests performed at the ISIS spallation neutron source in UK. The device represents a novel approach in the field of pulsed fast-neutrons spectroscopic techniques. It will find immediate application in localized (mm resolution) fast-neutron fluence measurements required by neutron irradiation experiments at ISIS also envisaging its use for spectrum measurements.

Pietropaolo, A.; Andreani, C.; Rebai, M.; Giacomelli, L.; Gorini, G.; Perelli Cippo, E.; Tardocchi, M.; Fazzi, A.; Verona Rinati, G.; Verona, C.; Marinelli, M.; Milani, E.; Frost, C. D.; Schooneveld, E. M.

2010-12-01

317

Thermal emittance and response time of a cesium antimonide photocathode  

Science.gov (United States)

Measurements of the intrinsic emittance and response time of a Cs3Sb photocathode are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. Photoemission response time is evaluated using a RF deflecting cavity synchronized to a picosecond laser pulse train. We find that Cs3Sb has both small mean transverse energy, 160 ± 10 meV at 532 nm laser wavelength, and a prompt response time (below the resolution of our measurement) making it a suitable material for high brightness electron photoinjectors.

Cultrera, Luca; Bazarov, Ivan; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Merluzzi, Richard; Nichols, Matthew

2011-10-01

318

Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing  

Energy Technology Data Exchange (ETDEWEB)

In the framework of the construction of the double time-of-flight spectrometer VERDI, where we aim at measuring pre- and post-neutron masses directly and simultaneously, ultra-fast time pick-up detectors based on artificial diamond material were investigated for the first time with fission fragments from {sup 252}Cf (0.5MeV/utiming resolution of a 100?m thick polycrystalline CVD diamond detector with a size of 1×1 cm{sup 2} was determined to ?{sub int}=(283±41)ps by comparison with Monte-Carlo simulations. Using broadband pre-amplifiers, 4-fold segmented detectors of same total size and with a thickness of 180?m show an intrinsic timing resolution of ?{sub int}=(106±21)ps. This is highly competitive with the best micro-channel plate detectors. Due to the limited and batch-dependent charge collection efficiency of poly-crystalline diamond material, the detection efficiency for fission fragments may be smaller than 100%. -- Highlights: ? First use of chemical vapor deposited diamond for heavy ions with kinetic energies below 2 MeV per nucleon. ? Fission-fragment time-of-flight measurements with a timing resolution better than 150 ps. ? Radiation-hard fission event trigger to be used in an intense neutron field.

Oberstedt, S., E-mail: stephan.oberstedt@ec.europa.eu [European Commission, DG Joint Research Centre (IRMM), B-2440 Geel (Belgium); Borcea, R.; Bry?, T.; Gamboni, Th.; Geerts, W.; Hambsch, F.-J. [European Commission, DG Joint Research Centre (IRMM), B-2440 Geel (Belgium); Oberstedt, A. [Fundamental Fysik, Chalmers Tekniska Högskola, S-41296 Göteborg (Sweden); Akademin för Naturvetenskap och Technik, Örebro Universitet, S-70182 Örebro (Sweden); Vidali, M. [European Commission, DG Joint Research Centre (IRMM), B-2440 Geel (Belgium)

2013-06-21

319

Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing  

International Nuclear Information System (INIS)

In the framework of the construction of the double time-of-flight spectrometer VERDI, where we aim at measuring pre- and post-neutron masses directly and simultaneously, ultra-fast time pick-up detectors based on artificial diamond material were investigated for the first time with fission fragments from 252Cf (0.5MeV/u9 fission-fragments/cm2 together with more than 3.5×109 neutrons/cm2 and 3×1010?-particles/cm2. This fluence is characteristic for fission experiments. The pre-requisite for the observed signal stability is the application of priming of the diamond material with a strong ?-source for about 48 h. The intrinsic timing resolution of a 100?m thick polycrystalline CVD diamond detector with a size of 1×1 cm2 was determined to ?int=(283±41)ps by comparison with Monte-Carlo simulations. Using broadband pre-amplifiers, 4-fold segmented detectors of same total size and with a thickness of 180?m show an intrinsic timing resolution of ?int=(106±21)ps. This is highly competitive with the best micro-channel plate detectors. Due to the limited and batch-dependent charge collection efficiency of poly-crystalline diamond material, the detection efficiency for fission fragments may be smaller than 100%. -- Highlights: ? First use of chemical vapor deposited diamond for heavy ions with kinetic energies below 2 MeV per nucleon. ? Fission-fragment time-of-flight measurements with a timing resolution better than 150 ps. ? Radiation-hard fission event trigger to be used in an intense neutron field

320

Time dependent start-up thermal analysis of a Super Fast Reactor  

International Nuclear Information System (INIS)

Highlights: • Time dependent startup thermal analysis of a Super Fast Reactor is performed. • A recirculation system is used for pressurization and for generating supercritical steam. • MCST satisfies the criterion both during subcritical pressure and during power-raising. • MCST is not sensitive to the change of inlet temperature, gap volume and flow rate because of high flow to power ratio. • CHF is not limiting the MCST during subcritical pressure due to large margin of heat flux. -- Abstract: The startup system of a supercritical pressure light water cooled fast reactor (Super FR) is studied by time dependent thermal-hydraulic analysis. The plant analysis code is developed based on an innovative upward flow pattern in all the assemblies of the Super FR. A recirculation system consisting of a steam drum, a circulation pump, and a heat exchanger is used for the startup. Detailed procedures are performed and the maximum cladding surface temperature (MCST) at rated power, 640 °C, is used as the criterion. Firstly a small constant nuclear power is used for rising the core feed water temperature to be 280 °C through the recirculation system. Secondly, pressurization is done in the recirculation system from atmospheric to operating pressure, 25 MPa, by raising the power. Thirdly, line-switching from recirculation mode to once-through direct-cycle is performed while turbines are started by supercritical steam at supercritical pressure. Finally the power is raised to be 100% of power followed by raising the flow rate. During pressurization the heat flux margin is large due to low power used for pressurization and the MCST is much lower than the criterion. The MCST is not sensitive to the inlet temperature, the flow rate, and the gap volume of the core because of high flow to power ratio. Smaller dimension of steam drum can be used for pressurization stably. The MCST satisfies the criterion both during subcritical pressure and during power-raising

 
 
 
 
321

Time dependent start-up thermal analysis of a Super Fast Reactor  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • Time dependent startup thermal analysis of a Super Fast Reactor is performed. • A recirculation system is used for pressurization and for generating supercritical steam. • MCST satisfies the criterion both during subcritical pressure and during power-raising. • MCST is not sensitive to the change of inlet temperature, gap volume and flow rate because of high flow to power ratio. • CHF is not limiting the MCST during subcritical pressure due to large margin of heat flux. -- Abstract: The startup system of a supercritical pressure light water cooled fast reactor (Super FR) is studied by time dependent thermal-hydraulic analysis. The plant analysis code is developed based on an innovative upward flow pattern in all the assemblies of the Super FR. A recirculation system consisting of a steam drum, a circulation pump, and a heat exchanger is used for the startup. Detailed procedures are performed and the maximum cladding surface temperature (MCST) at rated power, 640 °C, is used as the criterion. Firstly a small constant nuclear power is used for rising the core feed water temperature to be 280 °C through the recirculation system. Secondly, pressurization is done in the recirculation system from atmospheric to operating pressure, 25 MPa, by raising the power. Thirdly, line-switching from recirculation mode to once-through direct-cycle is performed while turbines are started by supercritical steam at supercritical pressure. Finally the power is raised to be 100% of power followed by raising the flow rate. During pressurization the heat flux margin is large due to low power used for pressurization and the MCST is much lower than the criterion. The MCST is not sensitive to the inlet temperature, the flow rate, and the gap volume of the core because of high flow to power ratio. Smaller dimension of steam drum can be used for pressurization stably. The MCST satisfies the criterion both during subcritical pressure and during power-raising.

Sutanto,, E-mail: sutanto@fuji.waseda.jp; Oka, Yoshiaki

2013-10-15

322

Fast Padé Transform for Exact Quantification of Time Signals in Magnetic Resonance Spectroscopy  

Science.gov (United States)

This work employs the fast Padé transform (FPT) for spectral analysis of theoretically generated time signals. The spectral characteristics of these synthesised signals are reminiscent of the corresponding data that are measured experimentally via encoding digitised free induction decay curves from a healthy human brain using Magnetic Resonance Spectroscopy (MRS). In medicine, in vivo MRS is one of the most promising non-invasive diagnostic tools, especially in oncology, due to the provided biochemical information about functionality of metabolites of the scanned tissue. For success of such diagnostics, it is crucial to carry out the most reliable quantifications of the studied time signals. This quantification problem is the harmonic inversion via the spectral decomposition of the given time signal into its damped harmonic constituents. Such a reconstruction finds the unknown total number of resonances, their complex frequencies and the corresponding complex amplitudes. These spectral parameters of the fundamental harmonics give the peak positions, widths, heights, and phases of all the physical resonances. As per the unified theory of quantum-mechanical spectral analysis and signal processing, the FPT represents the exact solver of the quantification problem, which is mathematically ill-conditioned. The exact and unique solution via the FPT is valid for any noiseless synthesised time signal built from an arbitrary number of damped complex exponentials. These attenuated harmonics can appear as a linear combination with both stationary and non-stationary amplitudes. Such sums produce time signals that yield Lorentzian (non-degenerate) and non-Lorentzian (degenerate) spectra for isolated and overlapped resonances from MRS. We give a convergent validation for these virtues of the FPT. This is achieved through the proof-of-principle investigation by developing an algorithmic feasibility for robust and efficient computations of the exact numerical solution of a typical quantification problem from MRS. The systematics in the methodology designed in the present study represent a veritable paradigm shift for solving the quantification problem in MRS with special ramifications in clinical oncology. This is implied by the explicit demonstration of the remarkable ability of the fast Padé transform to unambiguously quantify all the customary spectral structures, ranging from isolated resonances to those that are tightly overlapped and nearly confluent.

Belkic, Dzevad

323

Planck 2013 results. VII. HFI time response and beams  

CERN Document Server

This paper characterizes the effective beams, the effective beam window functions (EBWF) and the associated errors for the Planck High Frequency Instrument (HFI) detectors. The effective beam is the angular response including the effect of the optics, detectors, data processing and the scan strategy. The EBWF is the representation of this beam in the harmonic domain that is required to recover an unbiased measurement of the Cosmic Microwave Background (CMB) angular power spectrum. The HFI is a scanning instrument and its effective beams are the convolution of the optical response of the telescope and feeds, the processing of the time-ordered data and deconvolution of the bolometric and electronic time response, and the merging of several surveys to produce maps. The time response transfer functions are measured with observations of Jupiter and Saturn and by minimizing survey difference residuals. The scanning beam is the post-deconvolution angular response of the instrument, and is characterized with observat...

Ade, P A R; Armitage-Caplan, C; Arnaud, M; Ashdown, M; Atrio-Barandela, F; Aumont, J; Baccigalupi, C; Banday, A J; Barreiro, R B; Battaner, E; Benabed, K; Benoît, A; Benoit-Lévy, A; Bernard, J -P; Bersanelli, M; Bielewicz, P; Bobin, J; Bock, J J; Bond, J R; Borrill, J; Bouchet, F R; Bowyer, J W; Bridges, M; Bucher, M; Burigana, C; Cardoso, J -F; Catalano, A; Challinor, A; Chamballu, A; Chary, R -R; Chiang, L -Y; Chiang, H C; Christensen, P R; Church, S; Clements, D L; Colombi, S; Colombo, L P L; Couchot, F; Coulais, A; Crill, B P; Curto, A; Cuttaia, F; Danese, L; Davies, R D; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Désert, F -X; Diego, J M; Dole, H; Donzelli, S; Doré, O; Douspis, M; Dunkley, J; Dupac, X; Efstathiou, G; Enßlin, T A; Eriksen, H K; Finelli, F; Forni, O; Frailis, M; Fraisse, A A; Franceschi, E; Galeotta, S; Ganga, K; Giard, M; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Gruppuso, A; Gudmundsson, J E; Haissinski, J; Hansen, F K; Hanson, D; Harrison, D; Henrot-Versillé, S; Hernández-Monteagudo, C; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hornstrup, A; Hou, Z; Hovest, W; Huffenberger, K M; Jaffe, T R; Jaffe, A H; Jones, W C; Juvela, M; Keihänen, E; Keskitalo, R; Kisner, T S; Kneissl, R; Knoche, J; Knox, L; Kunz, M; Kurki-Suonio, H; Lagache, G; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lawrence, C R; Leonardi, R; Leroy, C; Lesgourgues, J; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; MacTavish, C J; Maffei, B; Mandolesi, N; Maris, M; Marshall, D J; Martin, P G; Martínez-González, E; Masi, S; Matarrese, S; Matsumura, T; Matthai, F; Mazzotta, P; McGehee, P; Melchiorri, A; Mendes, L; Mennella, A; Migliaccio, M; Mitra, S; Miville-Deschênes, M -A; Moneti, A; Montier, L; Morgante, G; Mortlock, D; Munshi, D; Murphy, J A; Naselsky, P; Nati, F; Natoli, P; Netterfield, C B; Nørgaard-Nielsen, H U; Noviello, F; Novikov, D; Novikov, I; Osborne, S; Oxborrow, C A; Paci, F; Pagano, L; Pajot, F; Paoletti, D; Pasian, F; Patanchon, G; Perdereau, O; Perotto, L; Perrotta, F; Piacentini, F; Piat, M; Pierpaoli, E; Pietrobon, D; Plaszczynski, S; Pointecouteau, E; Polegre, A M; Polenta, G; Ponthieu, N; Popa, L; Poutanen, T; Pratt, G W; Prézeau, G; Prunet, S; Puget, J -L; Rachen, J P; Reinecke, M; Remazeilles, M; Renault, C; Ricciardi, S; Riller, T; Ristorcelli, I; Rocha, G; Rosset, C; Roudier, G; Rowan-Robinson, M; Rusholme, B; Sandri, M; Santos, D; Sauvé, A; Savini, G; Shellard, E P S; Spencer, L D; Starck, J -L; Stolyarov, V; Stompor, R; Sudiwala, R; Sureau, F; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Tavagnacco, D; Terenzi, L; Tomasi, M; Tristram, M; Tucci, M; Umana, G; Valenziano, L; Valiviita, J; Van Tent, B; Vielva, P; Villa, F; Vittorio, N; Wade, L A; Wandelt, B D; Yvon, D; Zacchei, A; Zonca, A

2013-01-01

324

Improved time response for large area microchannel plate photomultiplier tubes in fusion diagnosticsa)  

Science.gov (United States)

Fusion diagnostics that utilise high speed scintillators often need to capture a large area of light with a high degree of time accuracy. Microchannel plate (MCP) photomultiplier tubes (PMTs) are recognised as the leading device for capturing fast optical signals. However, when manufactured in their traditional proximity focused construction, the time response performance is reduced as the active area increases. This is due to two main factors: the capacitance of a large anode and the difficulty of obtaining small pore MCPs with a large area. Collaboration between Photek and AWE has produced prototype devices that combine the excellent time response of small area MCP-PMTs with a large active area by replacing the traditional proximity-gap front section with an electro-optically focused photocathode to MCP. We present results from both single and double MCP devices with a 40 mm diameter active area and show simulations for the 100 mm device being built this year.

Milnes, J. S.; Horsfield, C. J.; Conneely, T. M.; Howorth, J.

2014-11-01

325

Multi-purpose fast neutron spectrum analyzer with real-time signal processing  

Science.gov (United States)

Diagnostics of hot ion component of plasma on the products of fusion reactions is widely used on thermonuclear facilities. In case of employment of neutron spectrometers, based on organics scintillators, there is advanced technique developed to eliminate neutron pulses from gamma background—digital pulse shape discrimination. For every DPSD application it is necessary to use the fast (2-5 ns) and precise (12 bit) transient ADC unit with large amount of onboard memory for storing every digitized scintillation pulses during shot time. At present time the duration of hot thermonuclear plasma burning in large tokamaks approximate to 1 min, and this requires very high onboard memory capacity (˜100 GB). This paper describes a neutron spectrum analyzer with real-time DPSD algorithm, implemented to ADC unit. This approach saves about two orders of onboard memory capacity, gives the possibility of instant use of outcome to feedback systems. This analyzer was tested and calibrated with help of 60Co and 252Cf radiation sources, and deuterium neutron generator.

Sulyaev, Yu. S.; Puryga, E. A.; Khilchenko, A. D.; Kvashnin, A. N.; Polosatkin, S. V.; Rovenskikh, A. F.; Burdakov, A. V.; Grishnyaev, E. V.

2013-08-01

326

Multi-purpose fast neutron spectrum analyzer with real-time signal processing  

International Nuclear Information System (INIS)

Diagnostics of hot ion component of plasma on the products of fusion reactions is widely used on thermonuclear facilities. In case of employment of neutron spectrometers, based on organics scintillators, there is advanced technique developed to eliminate neutron pulses from gamma background—digital pulse shape discrimination. For every DPSD application it is necessary to use the fast (2–5 ns) and precise (12 bit) transient ADC unit with large amount of onboard memory for storing every digitized scintillation pulses during shot time. At present time the duration of hot thermonuclear plasma burning in large tokamaks approximate to 1 min, and this requires very high onboard memory capacity (?100 GB). This paper describes a neutron spectrum analyzer with real-time DPSD algorithm, implemented to ADC unit. This approach saves about two orders of onboard memory capacity, gives the possibility of instant use of outcome to feedback systems. This analyzer was tested and calibrated with help of 60Co and 252Cf radiation sources, and deuterium neutron generator

327

A real-time fast radio burst: polarization detection and multiwavelength follow-up  

CERN Document Server

Fast radio bursts (FRBs) are one of the most tantalizing mysteries of the radio sky; their progenitors and origins remain unknown and until now no rapid multiwavelength follow-up of an FRB has been possible. New instrumentation has decreased the time between observation and discovery from years to seconds, and enables polarimetry to be performed on FRBs for the first time. We have discovered an FRB (FRB 140514) in real-time on 14 May, 2014 at 17:14:11.06 UTC at the Parkes radio telescope and triggered follow-up at other wavelengths within hours of the event. FRB 140514 was found with a dispersion measure (DM) of 562.7(6) cm$^{-3}$ pc, giving an upper limit on source redshift of $z \\lesssim 0.5$. FRB 140514 was found to be 21$\\pm$7% (3-$\\sigma$) circularly polarized on the leading edge with a 1-$\\sigma$ upper limit on linear polarization $<10%$. We conclude that this polarization is intrinsic to the FRB. If there was any intrinsic linear polarization, as might be expected from coherent emission, then it may...

Petroff, E; Barr, E D; Barsdell, B R; Bhat, N D R; Bian, F; Burke-Spolaor, S; Caleb, M; Champion, D; Chandra, P; Da Costa, G; Delvaux, C; Flynn, C; Gehrels, N; Greiner, J; Jameson, A; Johnston, S; Kasliwal, M M; Keane, E F; Keller, S; Kocz, J; Kramer, M; Leloudas, G; Malesani, D; Mulchaey, J S; Ng, C; Ofek, E O; Perley, D A; Possenti, A; Schmidt, B P; Shen, Yue; Stappers, B; Tisserand, P; van Straten, W; Wolf, C

2014-01-01

328

Elements for Response Time Statistics in ERP Transaction Systems  

CERN Document Server

We present some measurements and ideas for response time statistics in ERP systems. It is shown that the response time distribution of a given transaction in a given system is generically a log-normal distribution or, in some situations, a sum of two or more log-normal distributions. We present some arguments for this form of the distribution based on heuristic rules for response times, and we show data from performance measurements in actual systems to support the log-normal form. Deviations of the log-normal form can often be traced back to performance problems in the system. Consequences for the interpretation of response time data and for service level agreements are discussed.

Mielke, A

2004-01-01

329

Time domain modeling of tunable response of graphene  

DEFF Research Database (Denmark)

We present a causal numerical model for time domain simulations of the optical response of graphene. The dielectric function is approximated with a conductivity term, a Drude term and a number of the critical points terms.

Boltasseva, Alexandra

2013-01-01

330

On-line automatic sensor response time analysis system  

International Nuclear Information System (INIS)

An on-line automatic sensor response time analysis system in Taipower's Maanshan PWR nuclear power plant is presented. The algorithm applied in the system is the noise analysis technique which is an indirect method of determining sensor response time. This technique includes the power spectral density analysis and the autoregressive analysis methods. The system can also be used for long-term surveillance of sensor performance trends and cross-comparison of redundant sensors for predictive maintenance purposes. (author)

331

Experience with RTD response time testing in nuclear power plants  

International Nuclear Information System (INIS)

The reactor coolant temperatures in pressurized water reactors are measured with platinum resistance temperature detectors (RTDs). The information furnished by these RTDs is used for plant protection as well as control. As a part of the plant protection system, the RTDs must respond to temperature changes in a timely fashion. The RTD response time requirements are different for the various plant types. These requirements are specified in the plant technical specifications in terms of an RTd time constant. The current time constant requirements for nuclear plant RTDs varies from 0.5 seconds to 13.0 seconds depending on the type of the plant. Therefore, different types of RTDs are used in different plants to achieve the required time constants. In addition, in-situ response time tests are periodically performed on protective system RTDs to ensure that the in-service time constants are within acceptable limits as the plant is operating. The periodic testing is important because response time degradation may occur while the RTD ages in the process. Recent response time tests in operating plants revealed unacceptable time constants for several protection system RTDs. As a result, these plants had to be shut down to resolve the problem which in one case was due to improper installation and in another case was because of degradation of a thermal compound used in the thermowell

332

Measure of the speed of gamma-rays as a test of the performance of a fast timing coincidence system  

Energy Technology Data Exchange (ETDEWEB)

The speed of the gamma-rays obtained from positron annihilation has been measured as a test of the long-term stability of a fast timing coincidence system. The value c=(2.9978{+-}0.0002)10{sup 8} m/s has been obtained, whose precision is the best among those obtained from nuclear timing techniques. ((orig.))

Falciglia, F. [Laboratorio Nazionale des Sud, INFN, Catania (Italy)]|[Catania Univ. (Italy). Istituto di Fisica; Lo Savio, F.R. [Catania Univ. (Italy). Istituto di Macchine; Lo Savio, M. [Laboratorio Nazionale des Sud, INFN, Catania (Italy)]|[Catania Univ. (Italy). Istituto di Fisica; Oliveri, M.E. [Laboratorio Nazionale des Sud, INFN, Catania (Italy)]|[Catania Univ. (Italy). Istituto di Fisica; Patane, F. [Catania Univ. (Italy). Istituto di Macchine

1995-02-15

333

Measure of the speed of gamma-rays as a test of the performance of a fast timing coincidence system  

International Nuclear Information System (INIS)

The speed of the gamma-rays obtained from positron annihilation has been measured as a test of the long-term stability of a fast timing coincidence system. The value c=(2.9978±0.0002)108 m/s has been obtained, whose precision is the best among those obtained from nuclear timing techniques. ((orig.))

334

Studies on the response of 3He and 4He proportional counters to monoenergetic fast neutrons  

International Nuclear Information System (INIS)

Two helium filled proportional counters (3He and 4He) were studied to establish the optimum operating conditions when these counters are used for fast neutron measurements, as well as to examine the linearity of the pulse height with neutron energy. The detectors were irradiated with mono-energetic neutrons in the energy range of 230 keV-22 MeV, produced via 7Li(n,p)7Be, 2H(d,n)3He and 3H(d,n)4He reactions in a Tandem Van de Graff accelerator. The gamma ray contribution to the obtained pulse height distribution and the resolution of the counters as a function of shaping time constant and applied high voltage were studied

335

Silicon-on-insulator thermo-optic variable attenuator module with fast response  

Science.gov (United States)

A thermo-optic variable optical attenuator module composed of a silicon-on-insulator attenuator chip and driving circuit was designed and fabricated. The module exhibited a maximum attenuation of 21.8 dB and a response time of 10 µs.

Li, Yuntao; Chen, Yuanyuan; Liu, Shaowu; Yu, Jinzhong

2005-06-01

336

ZnO(N)-Spiro-MeOTAD hybrid photodiode: an efficient self-powered fast-response UV (visible) photosensor  

Science.gov (United States)

Organic-inorganic hybrid photo-detectors with a self-sufficient mode of operation represent a research area of great current interest. In most efficient photodetectors and optoelectronic devices compound semiconductors containing toxic elements such as Cd, As, Te, S, Se etc. are used and these are also expensive. Hence there is also a rapidly growing interest in replacing these with environmentally friendly and earth-abundant materials. Herein, we report a facile solution-processed fabrication of a self-powered organic-inorganic hybrid photodetector using n-type oriented ZnO nanorods and p-type Spiro-MeOTAD semiconductor. ZnO is eco-friendly and earth-abundant, and Spiro-MeOTAD is non-hazardous. We show that the latter has far less toxicity than the toxic elements stated above. This visible blind UV photodetector shows high sensitivity (102) and a UV/visible rejection ratio of 300. It also exhibits fast response times of ?rise ~ 200 ?s and ?fall ~ 950 ?s. Importantly, with a small modification of nitrogen incorporation in ZnO one can also realize a highly-sensitive self-powered visible light photodetector with at least 1000% (or higher) improvements in quality factors (photocurrent/sensitivity/response time) as compared to previously reported organic-inorganic hybrid photo-detectors based on metal-chalcogenides (CdS-PANI or CuInSe2-P3HT). Interestingly, the broadband sensitivity of such N:ZnO-Spiro-MeOTAD photodiode enables sensing of low intensity (~28 ?W cm-2) ambient white light with a high photocurrent density of 120 nA cm-2 making it an efficient ambient white light detector.Organic-inorganic hybrid photo-detectors with a self-sufficient mode of operation represent a research area of great current interest. In most efficient photodetectors and optoelectronic devices compound semiconductors containing toxic elements such as Cd, As, Te, S, Se etc. are used and these are also expensive. Hence there is also a rapidly growing interest in replacing these with environmentally friendly and earth-abundant materials. Herein, we report a facile solution-processed fabrication of a self-powered organic-inorganic hybrid photodetector using n-type oriented ZnO nanorods and p-type Spiro-MeOTAD semiconductor. ZnO is eco-friendly and earth-abundant, and Spiro-MeOTAD is non-hazardous. We show that the latter has far less toxicity than the toxic elements stated above. This visible blind UV photodetector shows high sensitivity (102) and a UV/visible rejection ratio of 300. It also exhibits fast response times of ?rise ~ 200 ?s and ?fall ~ 950 ?s. Importantly, with a small modification of nitrogen incorporation in ZnO one can also realize a highly-sensitive self-powered visible light photodetector with at least 1000% (or higher) improvements in quality factors (photocurrent/sensitivity/response time) as compared to previously reported organic-inorganic hybrid photo-detectors based on metal-chalcogenides (CdS-PANI or CuInSe2-P3HT). Interestingly, the broadband sensitivity of such N:ZnO-Spiro-MeOTAD photodiode enables sensing of low intensity (~28 ?W cm-2) ambient white light with a high photocurrent density of 120 nA cm-2 making it an efficient ambient white light detector. Electronic supplementary information (ESI) available: SI-1: response time measurements of self powered hybrid ZnO-SPD under nanosecond pulsed UV laser, SI-2: Raman analysis of N:ZnO and ZnO SI-3: cytotoxicity study on Spiro-MeOTAD SI-4: electrochemical Mott-Schottky plots of ZnO and N:ZnO. See DOI: 10.1039/c3nr04727j

Game, Onkar; Singh, Upendra; Kumari, Tanya; Banpurkar, Arun; Ogale, Satishchandra

2013-12-01

337

A comparison of two procedures for verbal response time fractionation  

Science.gov (United States)

To describe the mental architecture between stimulus and response, cognitive models often divide the stimulus-response (SR) interval into stages or modules. Predictions derived from such models are typically tested by focusing on the moment of response emission, through the analysis of response time (RT) distributions. To go beyond the single response event, we recently proposed a method to fractionate verbal RTs into two physiologically defined intervals that are assumed to reflect different processing stages. The analysis of the durations of these intervals can be used to study the interaction between cognitive and motor processing during speech production. Our method is inspired by studies on decision making that used manual responses, in which RTs were fractionated into a premotor time (PMT), assumed to reflect cognitive processing, and a motor time (MT), assumed to reflect motor processing. In these studies, surface EMG activity was recorded from participants' response fingers. EMG onsets, reflecting the initiation of a motor response, were used as the point of fractionation. We adapted this method to speech-production research by measuring verbal responses in combination with EMG activity from facial muscles involved in articulation. However, in contrast to button-press tasks, the complex task of producing speech often resulted in multiple EMG bursts within the SR interval. This observation forced us to decide how to operationalize the point of fractionation: as the first EMG burst after stimulus onset (the stimulus-locked approach), or as the EMG burst that is coupled to the vocal response (the response-locked approach). The point of fractionation has direct consequences on how much of the overall task effect is captured by either interval. Therefore, the purpose of the current paper was to compare both onset-detection procedures in order to make an informed decision about which of the two is preferable. We concluded in favor or the response-locked approach. PMID:25386153

van der Linden, Lotje; Riès, Stéphanie K.; Legou, Thierry; Burle, Borís; Malfait, Nicole; Alario, F.-Xavier

2014-01-01

338

Time response of temperature sensors using neural networks  

International Nuclear Information System (INIS)

Primary coolant RTDs (Resistance Temperature Detector) typically feed the plant's control and safety systems and must, therefore, be very accurate and have good dynamic performance. The response time of RTDs has been characterized by a single parameter called the time constant defined as the time it takes for the sensor output to achieve 63.2 percent of its final value after a step change in temperature. This step change is typically achieved by suddenly immersing the sensor in a rotating tank of water, called Plunge Test. In nuclear reactors, however, plunge testing is inconvenient because nuclear reactor service conditions are difficult to reproduce in the laboratory. An in-situ test method called LCSR - Loop Current Step Response test was developed to measure remotely the response time of RTDs. In the LCSR method, the response time of the sensor is identified by means of the LCSR transformation that involves the dynamic response modal time constants determination using a nodal heat-transfer model. For this reason, this calculation is not simple and requires specialized personnel. This work combines the two methodologies, Plunge test and LCSR test, using neural networks. With the use of neural networks it will not be necessary to use the LCSR transformation to determine sensor's time constant and this leads to more robust results. (author)

339

Drude response of slow and fast electrons in the heavy-fermion compound UNi2Al3  

International Nuclear Information System (INIS)

The unusual metallic behavior of heavy-fermion compounds at low temperatures is caused by mobile charge carriers with a large effective mass. This mass enhancement (compared to normal electrons) goes hand in hand with a reduction of the transport scattering time, which can directly be studied with optical spectroscopy: the characteristic Drude roll-off moves to very low frequencies. Here we combine microwave and THz spectroscopy to study thin films of the heavy-fermion compound UNi2Al3 in a broad frequency range. At frequencies of a few GHz, a full Drude response indicates the dynamics of the heavy electrons in UNi2Al3. Surprisingly, at considerably higher frequencies (around 300 GHz) we observe a similar structure that is very reminiscent of Drude behavior. We interpret these two features as the Drude response of - at low frequencies - correlated, slow electrons and - at higher frequencies - uncorrelated, fast electrons. The temperature dependence and anisotropy of these two Drude roll-offs correspond to each other. These results also shed new light on previous studies of the related compound UPd2Al3.

340

Time response of temperature sensors using neural networks  

International Nuclear Information System (INIS)

In a PWR nuclear power plant, the primary coolant temperature and feedwater temperature are measured using RTDs (Resistance Temperature Detectors). These RTDs typically feed the plant's control and safety systems and must, therefore, be very accurate and have good dynamic performance. The response time of RTDs is characterized by a single parameter called the Plunge Time Constant defined as the time it takes the sensor output to achieve 63.2 percent of its final value after a step change in temperature. Nuclear reactor service conditions are difficult to reproduce in the laboratory, and an in-situ test method called LCSR (Loop Current Step Response) test was developed to measure remotely the response time of RTDs. >From this test, the time constant of the sensor is identified by means of the LCSR transformation that involves the dynamic response modal time constants determination using a nodal heat-transfer model. This calculation is not simple and requires specialized personnel. For this reason an Artificial Neural Network has been developed to predict the time constant of RTD from LCSR test transient. It eliminates the transformations involved in the LCSR application. A series of LCSR tests on RTDs generates the response transients of the sensors, the input data of the networks. Plunge tests are used to determine the time constants of the RTDs, the desired output of the ANN, trained using these sets of input/output data. This methodology was firstly applied to theoretical data simulating 10 RTDs with different time constant values, resulting in an average error of about 0.74 %. Experimental data from three different RTDs was used to predict time constant resulting in a maximum error of 3,34 %. The time constants values predicted from ANN were compared with those obtained from traditional way resulting in an average error of about 18 % and that shows the network is able to predict accurately the sensor time constant. (author)

 
 
 
 
341

Fast Time-Domain Edge-Diffraction Calculations for Interactive Acoustic Simulations  

Directory of Open Access Journals (Sweden)

Full Text Available The inclusion of edge diffraction has long been recognized as an improvement to geometrical-acoustics (GA modeling techniques, particularly for acoustic simulations of complex environments that are represented as collections of finite-sized planar surfaces. One particular benefit of combining edge diffraction with GA components is that the resulting total sound field is continuous when an acoustic source or receiver crosses a specular-zone or shadow-zone boundary, despite the discontinuity experienced by the associated GA component. In interactive acoustic simulations which include only GA components, such discontinuities may be heard as clicks or other undesirable audible artifacts, and thus diffraction calculations are important for high perceptual quality as well as physical realism. While exact diffraction calculations are difficult to compute at interactive rates, approximate calculations are possible and sufficient for situations in which the ultimate goal is a perceptually plausible simulation rather than a numerically exact one. In this paper, we describe an edge-subdivision strategy that allows for fast time-domain edge-diffraction calculations with relatively low error when compared with results from a more numerically accurate solution. The tradeoff between computation time and accuracy can be controlled with a number of parameters, allowing the user to choose the speed that is necessary and the error that is tolerable for a specific modeling scenario.

Svensson U Peter

2007-01-01

342

Fast magnetosonic wave excitation by an array of wires with time-modulated currents  

Directory of Open Access Journals (Sweden)

Full Text Available The excitation of Fast Magnetosonic (FMS waves by a cylindrical array of parallel tethers carrying time-modulated current is discussed. The tethers would fly vertical in the equatorial plane, which is perpendicular to the geomagnetic field when its tilt is ignored, and would be stabilized by the gravity gradient. The tether array would radiate a single FMS wave. In the time-dependent background made of geomagnetic field plus radiated wave, plasma FMS perturbations are excited in the array vicinity through a parametric instability. The growth rate is estimated by truncating the evolution equation for FMS perturbations to the two azimuthal modes of lowest order. Design parameters such as tether length and number, required power and mass are discussed for Low Earth Orbit conditions. The array-attached wave structure would have the radiated wave controlled by the intensity and modulation frequency of the currents, making an active experiment on non-linear low frequency waves possible in real space plasma conditions.

G. Sanchez-Arriaga

2010-02-01

343

Time resolved measurement of FEL micropulses using fast hot electron bolometers  

International Nuclear Information System (INIS)

Radiation at 3THz or light of a 100?m wavelength generated with the THz-FEL at the Institute of Scientific and Industrial Research (ISIR), Osaka University is measured using two superconducting hot-electron bolometers (SHEB); one with a NbN (normal superconductor) detector and the other a YBCO (YBa2Cu3O7, high temperature superconductor) detector. Both detectors are fast enough to separately measure FEL micropulse at interval of 9.2 ns, which comprise four families of independent FEL micropulses. The single-shot time spectra, however, include significant amplitude noises compared to signals and hence it is difficult to analyze these spectra quantitatively. We try some kinds of numerical methods to reduce noises of the spectra measured with the YBCO detector and find the so-called MMSE-STSA (Minimum Mean-Square Error Short-Time Spectral Amplitude Estimator) method can significantly reduce effects of the noises. As a result, it is experimentally shown that four families of FEL micropulses develop independently and differently in the power saturation region. (author)

344

Photovoltaic response time in dual-gated bilayer graphene  

Science.gov (United States)

The intrinsic thermal response timescale of bilayer graphene is sub nanosecond, due to cooling of hot electrons mediated by acoustic phonon emission. We compare the response times of the photovoltaic and bolometric response as a function of temperature and dual-gate voltages in a gapped bilayer graphene device using a pulse coincidence technique at 1.5 ?m. We find that the photovoltaic and bolometric response time are identical and vary from 100 ps to 10 ps for temperatures from 3 K to 100 K. This result shows that the near IR photovoltaic response of bilayer graphene is thermal over this temperature range. This work was supported by IARPA, the ONR MURI program, and the NSF (grants DMR-0804976 and DMR-1105224), and in part by the NSF MRSEC (grant DMR-0520471).

Kim, M.-H.; Yan, J.; Suess, R. J.; Murphy, T.; Fuhrer, M. S.; Drew, H. D.

2013-03-01

345

High-Voltage Power Supply With Fast Rise and Fall Times  

Science.gov (United States)

A special-purpose high-voltage power supply can be electronically switched on and off with fast rise and fall times, respectively. The output potential is programmable from 20 to 1,250 V. An output current of 50 A can be sustained at 1,250 V. The power supply was designed specifically for electronically shuttering a microchannel plate in an x-ray detector that must operate with exposure times as short as 1 ms. The basic design of the power supply is also adaptable to other applications in which there are requirements for rapid slewing of high voltages. The power-supply circuitry (see figure) includes a preregulator, which is used to program the output at 1/30 of the desired output potential. After the desired voltage has been set, the outputs of a pulse width modulator (PWM) are enabled and used to amplify the preregulator output potential by 30. The amplification is achieved by use of two voltage doublers with a transformer that has two primary and two secondary windings. A resistor is used to limit the current by controlling the drive voltage of two field-effect transistors (FETs) during turn-on of the PWM. A pulse transformer is used to turn on four FETs to short-circuit four output capacitors when the outputs of the PWM have been disabled. The most notable aspects of the performance of the power supply are a rise time of only 80 s and a fall time of only 60 s at a load current of 50 A or less. Another notable aspect is that the application of a 0-to-5-V square wave to a shutdown pin of the PWM causes the production of a 0-to-1,250-V square wave at the output terminals.

Bearden, Douglas B.; Acker, Richard M.; Kapuslka, Robert E.

2007-01-01

346

Temperature Responses to Spectral Solar Variability on Decadal Time Scales  

Science.gov (United States)

Two scenarios of spectral solar forcing, namely Spectral Irradiance Monitor (SIM)-based out-of-phase variations and conventional in-phase variations, are input to a time-dependent radiative-convective model (RCM), and to the GISS modelE. Both scenarios and models give maximum temperature responses in the upper stratosphere, decreasing to the surface. Upper stratospheric peak-to-peak responses to out-of-phase forcing are approx.0.6 K and approx.0.9 K in RCM and modelE, approx.5 times larger than responses to in-phase forcing. Stratospheric responses are in-phase with TSI and UV variations, and resemble HALOE observed 11-year temperature variations. For in-phase forcing, ocean mixed layer response lags surface air response by approx.2 years, and is approx.0.06 K compared to approx.0.14 K for atmosphere. For out-of-phase forcing, lags are similar, but surface responses are significantly smaller. For both scenarios, modelE surface responses are less than 0.1 K in the tropics, and display similar patterns over oceanic regions, but complex responses over land.

Cahalan, Robert F.; Wen, Guoyong; Harder, Jerald W.; Pilewskie, Peter

2010-01-01

347

Modeling fast electron dynamics with real-time time-dependent density functional theory: application to small molecules and chromophores  

Energy Technology Data Exchange (ETDEWEB)

The response of matter to external fields forms the basis for a vast wealth of fundamental physical processes ranging from light harvesting to nanoscale electron transport. Accurately modeling ultrafast electron dynamics in excited systems thus o_ers unparalleled insight, but requires an inherently non-linear time-resolved approach. To this end, an e_cient and massively parallel real-time real-space time-dependent density functional theory (RT-TDDFT) implementation in NWChem is presented. The implementation is first validated against linearresponse TDDFT and experimental results for a series of molecules subjected to small electric field perturbations. Second, non-linear excitation of green fluorescent protein is studied, which shows a blue-shift in the spectrum with increasing perturbation, as well as a saturation in absorption. Next, the charge dynamics of optically excited zinc porphyrin is presented in real-time and real-space, with relevance to charge injection in photovoltaic devices. Finally, intermolecular excitation in an adenine-thymine base pair is studied using the BNL range separated functional [Baer, R.; Neuhauser, D. Phys. Rev. Lett. 2005, 94, 043002], demonstrating the utility of a real-time approach in capturing charge transfer processes.

Lopata, Kenneth A.; Govind, Niranjan

2011-05-10

348

Search for an optimum time response of spark counters  

CERN Document Server

A spark counter of the type developed by Pestov has been tested with the aim of searching for an optimum time response function, changing voltage, content of noble and quencher gases, pressure and energy-loss. Replacing the usual argon by neon has brought an improvement of the resolution and a significant reduction of tails in the time response function. It has been proven that a counter as long as 90 cm can deliver, using neon gas mixture, a time resolution sigma<60 ps with about 1% absolute tail and an efficiency of about 90%.

Devismes, A; Kress, T; Gobbi, A; Eschke, J; Herrmann, N; Hildenbrand, K D; Koczón, P; Petrovici, M

2002-01-01

349

Fast Responsive and Highly Efficient Optical Upconverter Based on Phosphorescent OLED.  

Science.gov (United States)

In this work, an organic-inorganic hybrid optical upconverter that can convert irradiated 980 nm IR light to 510 nm green phosphorescence sensitively was fabricated and studied. fac-Tris(2-phenylpyridine) iridium (Ir(ppy)3) doped 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) was used as emitting layer in the phosphorescent organic light-emitting diode (OLED) unit. The upconverter using a phosphorescent OLED as display unit can achieve a higher upconversion efficiency and a low power consumption when compared with the one using fluorescent. An upconversion efficiency of 4.8% can be achieved for phosphorescent device at 15 V, much higher than that of fluorescent one (2.0%). The upconverter's transient optical and electric response to IR pulse were also investigated for the first time. The response time was found to be influenced by IR intensity and applied voltage. It has a response time as short as 60 ?s. The rapid response property of the upconverter makes it feasible to be applied to high-speed IR imaging systems. PMID:25310022

Chu, Xinbo; Guan, Min; Niu, Litao; Zeng, Yiping; Li, Yiyang; Zhang, Yang; Zhu, Zhanping; Wang, Baoqiang

2014-11-12

350

Fast response air-to-fuel ratio measurements using a novel device based on a wide band lambda sensor  

International Nuclear Information System (INIS)

A crucial parameter influencing the formation of pollutant gases in internal combustion engines is the air-to-fuel ratio (AFR). During transients on gasoline and diesel engines, significant AFR excursions from target values can occur, but cycle-by-cycle AFR resolution, which is helpful in understanding the origin of deviations, is difficult to achieve with existing hardware. This is because current electrochemical devices such as universal exhaust gas oxygen (UEGO) sensors have a time constant of 50–100 ms, depending on the engine running conditions. This paper describes the development of a fast reacting device based on a wide band lambda sensor which has a maximum time constant of ?20 ms and enables cyclic AFR measurements for engine speeds of up to ?4000 rpm. The design incorporates a controlled sensor environment which results in insensitivity to sample temperature and pressure. In order to guide the development process, a computational model was developed to predict the effect of pressure and temperature on the diffusion mechanism. Investigations regarding the sensor output and response were carried out, and sensitivities to temperature and pressure are examined. Finally, engine measurements are presented

351

Fast response air-to-fuel ratio measurements using a novel device based on a wide band lambda sensor  

Science.gov (United States)

A crucial parameter influencing the formation of pollutant gases in internal combustion engines is the air-to-fuel ratio (AFR). During transients on gasoline and diesel engines, significant AFR excursions from target values can occur, but cycle-by-cycle AFR resolution, which is helpful in understanding the origin of deviations, is difficult to achieve with existing hardware. This is because current electrochemical devices such as universal exhaust gas oxygen (UEGO) sensors have a time constant of 50-100 ms, depending on the engine running conditions. This paper describes the development of a fast reacting device based on a wide band lambda sensor which has a maximum time constant of ~20 ms and enables cyclic AFR measurements for engine speeds of up to ~4000 rpm. The design incorporates a controlled sensor environment which results in insensitivity to sample temperature and pressure. In order to guide the development process, a computational model was developed to predict the effect of pressure and temperature on the diffusion mechanism. Investigations regarding the sensor output and response were carried out, and sensitivities to temperature and pressure are examined. Finally, engine measurements are presented.

Regitz, S.; Collings, N.

2008-07-01

352

Response Time Optimization for Replica Selection Service in Data Grids  

Directory of Open Access Journals (Sweden)

Full Text Available Problem Statement: Data Grid architecture provides a scalable infrastructure for grid services in order to manage data files and their corresponding replicas that were distributed across the globe. The grid services are designed to support a variety of data grid applications (jobs and projects. Replica selection is a high-level service that chooses a replica location from among many distributed replicas with the minimum response time for the users' jobs. Estimating the response time accurately in the grid environment is not an easy task. The current systems expose high response time in selecting the required replicas because the response time is estimated by considering the data transfer time only. Approach: We proposed a replica selection system that selects the best replica location for the users' running jobs in a minimum response time that can be estimated by considering new factors besides the data transfer time, namely, the storage access latency and the replica requests that waiting in the storage queue. Results: The performance of the proposed system was compared with a similar system that exists in the literature namely, SimpleOptimiser. The simulation results demonstrated that our system performed better than the SimpleOptimiser on an average of 6%. Conclusions: The proposed system can select the best replica location in a lesser response time than the SimpleOptimise. The efficiency of the proposed system is 6% higher than the SimpleOptimise. The efficiency level has a high impact on the quality of service that is perceived by grid users in a data grid environment where the data files are relatively big. For example, the data files produced from the scientific applications are of the size hundreds of Terabytes.

Husni H.E. AL-Mistarihi

2008-01-01

353

Synthesis of fast response crosslinked PVA-g-NIPAAm nanohydrogels by very low radiation dose in dilute aqueous solution  

Science.gov (United States)

Nanohydrogels of poly(vinyl alcohol)-g-N-isopropylacrylamide (PVA-g-NIPAAm) are synthesized by PVA and NIPAAm dilute aqueous solution using much less radiation dose of 1-20 Gy via intramolecular crosslinking at ambient temperature. The radiation synthesis of nanohydrogels is performed in the presence of tetrakis (hydroxymethyl) phosphonium chloride (THPC) due to its rapid oxygen scavenging abilities and hydrogen peroxide (H2O2) as a source of hydroxyl radicals. The effect of radiation dose, feed composition ratio of PVA and H2O2 is investigated on swelling properties such as temperature and pH dependence of equilibrium swelling ratio as well as deswelling kinetics. Experimental data exhibit high equilibrium swelling ratio and fast response time for the synthesized nanohydrogels. The average molecular weight between crosslinks (Mc) and crosslinking density (?x) of the obtained nanohydrogels are calculated from swelling data as a function of radiation dose, H2O2 and PVA amount. Fourier transform infrared spectroscopy (FT-IR), elemental analysis of nitrogen content and thermogravimetric analysis (TGA) are used to confirm the grafting reaction. Lower critical solution temperature (LCST) is measured around 33 °C by differential scanning calorimetry (DSC) for PVA-g-NIPAAm nanohydrogels. Dynamic light scattering (DLS) data demonstrate that the increase of radiation dose leads to the decreasing in dimension of nanohydrogels. Also, rheological studies are confirmed an improvement in the mechanical properties of the nanohydrogels with increasing the radiation dose. A cytotoxicity study exhibits a good biocompatibility for the obtained nanohydrogels. The prepared nanohydrogels show fast swelling/deswelling behavior, high swelling ratio, dual sensitivity and good cytocompatibility, which may find potential applications as biomaterial.

Fathi, Marziyeh; Reza Farajollahi, Ali; Akbar Entezami, Ali

2013-05-01

354

Real-time 3D medical structure segmentation using fast evolving active contours  

Science.gov (United States)

Segmentation of 3D medical structures in real-time is an important as well as intractable problem for clinical applications due to the high computation and memory cost. We propose a novel fast evolving active contour model in this paper to reduce the requirements of computation and memory. The basic idea is to evolve the brief represented dynamic contour interface as far as possible per iteration. Our method encodes zero level set via a single unordered list, and evolves the list recursively by adding activated adjacent neighbors to its end, resulting in active parts of the zero level set moves far enough per iteration along with list scanning. To guarantee the robustness of this process, a new approximation of curvature for integer valued level set is proposed as the internal force to penalize the list smoothness and restrain the list continual growth. Besides, list scanning times are also used as an upper hard constraint to control the list growing. Together with the internal force, efficient regional and constrained external forces, whose computations are only performed along the unordered list, are also provided to attract the list toward object boundaries. Specially, our model calculates regional force only in a narrowband outside the zero level set and can efficiently segment multiple regions simultaneously as well as handle the background with multiple components. Compared with state-of-the-art algorithms, our algorithm is one-order of magnitude faster with similar segmentation accuracy and can achieve real-time performance for the segmentation of 3D medical structures on a standard PC.

Wang, Xiaotao; Wang, Qiang; Hao, Zhihui; Xu, Kuanhong; Guo, Ping; Ren, Haibing; Jang, Wooyoung; Kim, Jung-bae

2014-03-01

355

Conceptual question response times in Peer Instruction classrooms  

Science.gov (United States)

Classroom response systems are widely used in interactive teaching environments as a way to engage students by asking them questions. Previous research on the time taken by students to respond to conceptual questions has yielded insights on how students think and change conceptions. We measure the amount of time students take to respond to in-class, conceptual questions [ConcepTests (CTs)] in two introductory physics courses taught using Peer Instruction and use item response theory to determine the difficulty of the CTs. We examine response time differences between correct and incorrect answers both before and after the peer discussion for CTs of varying difficulty. We also determine the relationship between response time and student performance on a standardized test of incoming physics knowledge, precourse self-efficacy, and gender. Our data reveal three results of interest. First, response time for correct answers is significantly faster than for incorrect answers, both before and after peer discussion, especially for easy CTs. Second, students with greater incoming physics knowledge and higher self-efficacy respond faster in both rounds. Third, there is no gender difference in response rate after controlling for incoming physics knowledge scores, although males register significantly more attempts before committing to a final answer than do female students. These results provide insight into effective CT pacing during Peer Instruction. In particular, in order to maintain a pace that keeps everyone engaged, students should not be given too much time to respond. When around 80% of the answers are in, the ratio of correct to incorrect responses rapidly approaches levels indicating random guessing and instructors should close the poll.

Miller, Kelly; Lasry, Nathaniel; Lukoff, Brian; Schell, Julie; Mazur, Eric

2014-12-01

356

Study on proliferation time and response time for proliferation resistance evaluation  

International Nuclear Information System (INIS)

'Proliferation time' is one of the proliferation resistance measures adopted by the Generation IV Nuclear Energy Systems International Forum (GIF) Proliferation Resistance and Physical Protection (PR and PP) evaluation methodology. A longer proliferation time would provide the international society with more time to intervene politically in order to dissuade the State from completing its nuclear weapons program. A longer proliferation time would therefore contribute to the enhancement of proliferation resistance of a given nuclear energy system. Two methods are considered for judging whether the proliferation time is long enough: 1) comparison of the proliferation times between a reference nuclear energy system and the subject system, and 2) comparison between the proliferation time and the response time, which can be defined as the time available to the international society to make a political intervention. This paper focuses on the latter method and examines how the response time can be estimated by reviewing prior incidents. (author)

357

Fast Direct Injection Mass-Spectrometric Characterization of Stimuli for Insect Electrophysiology by Proton Transfer Reaction-Time of Flight Mass-Spectrometry (PTR-ToF-MS  

Directory of Open Access Journals (Sweden)

Full Text Available Electrophysiological techniques are used in insect neuroscience to measure the response of olfactory neurons to volatile odour stimuli. Widely used systems to deliver an olfactory stimulus to a test insect include airstream guided flow through glass cartridges loaded with a given volatile compound on a sorbent support. Precise measurement of the quantity of compound reaching the sensory organ of the test organism is an urgent task in insect electrophysiology. In this study we evaluated the performances of the recent realised proton transfer reaction-time of flight mass-spectrometry (PTR-ToF-MS as a fast and selective gas sensor. In particular, we characterised the gas emission from cartridges loaded with a set of volatile compounds belonging to different chemical classes and commonly used in electrophysiological experiments. PTR-ToF-MS allowed a fast monitoring of all investigated compounds with sufficient sensitivity and time resolution. The detection and the quantification of air contaminants and solvent or synthetic standards impurities allowed a precise quantification of the stimulus exiting the cartridge. The outcome of this study was twofold: on one hand we showed that PTR-ToF-MS allows monitoring fast processes with high sensitivity by real time detection of a broad number of compounds; on the other hand we provided a tool to solve an important issue in insect electrophysiology.

Franco Biasioli

2012-03-01

358

Fast time-correlated multi-element photon detector and method  

Science.gov (United States)

Photons emitted from a sample responsive to being excited by laser pulses are directed through a prism onto a photomultiplier tube having several spaced-apart anodes. The prism alters the path of each photon as a function of its wavelength so that the wavelength determines the anode to which the photon is directed. Taps of first and second delay lines that are coupled to respective alternating anodes. When an anode receives the photon, it generates a pulse that propagates through the delay line in opposite directions from its associated tap. A timer determines first and second times from the laser pulse to the pulse reaching the first and second ends of the delay line. The difference between the first and second times corresponds to the wavelength of the emitted photon and the sum of the first and second times corresponds to the emission delay of the emitted photon.

Hayden, Carl C. (Dublin, CA); Chandler, David W. (Livermore, CA); Luong, A. Khai (Dublin, CA)

2007-12-18

359

Fast and wide-band response infrared detector using porous PZT pyroelectric thick film  

Science.gov (United States)

Porous lead zirconate titanate (PbZr0.3Ti0.7O3, PZT30/70) thick films and detectors for pyroelectric applications have been fabricated on alumina substrates by screen-printing technology. Low temperature sintering of PZT thick films have been achieved at 850 °C by using Li2CO3 and Bi2O3 sintering aids. The microstructure of PZT thick film has been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dielectric properties were measured using HP 4284 at 1 kHz under 25 °C. The permittivity and loss tangent of the thick films were 94 and 0.017, respectively. Curie temperature of PZT thick film was 425 °C as revealed by dielectric constant temperature measurement. The pyroelectric coefficient was determined to be 0.9 × 10-8 Ccm-2 K-1 by dynamic current measurement. Infrared detector sensitive element of dual capacitance was fabricated by laser directly write technology. Detectivity of the detectors were measured using mechanically chopped blackbody radiation. Detectivity ranging from 1.23 × 108 to 1.75 × 108 (cm Hz1/2 W-1) was derived at frequency range from 175.5 Hz to 1367 Hz, and D*'s -3 dB cut-off frequency bandwidth was 1.2 kHz. The results indicate that the infrared detectors based on porous thick films have great potential applications in fast and wide-band frequency response conditions.

Wu, C. G.; Sun, X. Y.; Meng, J.; Luo, W. B.; Li, P.; Peng, Q. X.; Luo, Y. S.; Shuai, Y.

2014-03-01

360

A fast dynamic response dc-dc converter for high voltage applications  

International Nuclear Information System (INIS)

This paper present a fast dynamic response de-de converter for high voltage application such as medical use X-ray generator. In the proposed de-de converter a zero-current switching series resonant inverter is used to drive input terminals of voltage multiplier circuit. The zero-current switching series resonant inverter operates at fixed frequency and duly ratio. A control circuit is used at the lower arm of the inverter, to control the effective input voltage across the inverter. At the turn on the inverter is supplied with maximum effective input voltage, which results in quick rise-up of the output voltage. As the output voltage approaches to 80% of it target voltage, the effective input voltage is reduced to a value which corresponds to the target output voltage, as a result the rise rate of the output voltage becomes slow and overshoot is avoided. The effectiveness of the proposed control scheme has been confirmed experimentally with a laboratory scale- down prototype. (author)

 
 
 
 
361

Hydriding/dehydriding characteristics on fast heat transfer response ZrCo bed for ITER  

Energy Technology Data Exchange (ETDEWEB)

Three models of fast heat transfer response ZrCo hydride bed were tested to examine their hydriding and dehydriding performance, and the hydrogen retention of the ZrCo during multiple hydriding and dehydriding operation. The design features of the present models are (i) very thin layer (3 mm) of ZrCo powder packing, (ii) large heating area in contact with the ZrCo powder (2.04 cm{sup 2}/g-ZrCo), and (iii) large filter surface area (1.76 cm{sup 2}/g-ZrCo) to reduce pressure drop across the filter during hydrogen delivery. To evaluate pumping conductance effect during dehydriding with vacuum pumping, two sizes of hydrogen pumping line were applied. Extremely high delivery rate of 1.3 x 10{sup -2} Pam{sup 3}/s for 90% delivery was observed in the 2nd and 3rd model tests. Hydrogen retention of {approx}1.5 x 10{sup -2} L-STP/g-ZrCo ({approx}2 L-STP/bed model) was observed in all models after multiple repetitions of hydridings and dehydriding under vacuum pumping: 25 cycles (1st model), 14 cycles (2nd model) and 70 cycles (3rd model). It was experimentally confirmed that the differences in the delivery rate and hydrogen retention the three model beds were predominantly generated by the difference in the pumping conductance (effective pumping speed) in the delivery pipeline.

Shim, Myunghwa [Korea Atomic Energy Research Institute, Yuseong, Daejeon 305-353 (Korea, Republic of); Chung, Hongsuk [Korea Atomic Energy Research Institute, Yuseong, Daejeon 305-353 (Korea, Republic of)], E-mail: hschung1@kaeri.kr; Yoshida, Hiroshi [Fusion Science Consultant, 3288-10, Sakado-cyo, Mito-shi, 310-0841 Ibakaki-ken (Japan); Jin, Haksu; Lee, Jongkuk [Korea Atomic Energy Research Institute, Yuseong, Daejeon 305-353 (Korea, Republic of); Song, Kyu-Min [KEPRI, Yuseong, Daejeon 305-380 (Korea, Republic of); Chang, Min Ho; Kang, Hyun-Goo; Yun, Sei-Hun; Cho, Seungyon [National Fusion Research Institute, Yuseong, Daejeon 305-333 (Korea, Republic of)

2009-06-15

362

Reduced computational cost in the calculation of worst case response time for real time systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Modern Real Time Operating Systems require reducing computational costs even though the microprocessors become more powerful each day. It is usual that Real Time Operating Systems for embedded systems have advance features to administrate the resources of the applications that they support. In order to guarantee either the schedulability of the system or the schedulability of a new task in a dynamic Real Time System, it is necessary to know the Worst Case Response Time of the Real Time tasks ...

Urriza, Jose? M.; Schorb, Lucas; Orozco, Javier D.; Cayssials, Ricardo

2009-01-01

363

Overview of the SPS/LEP fast broadcast message timing system  

International Nuclear Information System (INIS)

A fast broadcast message system, also referred to as the general machine timing system, has recently been installed at CERN's Super Proton Synchrotron (SPS). It is used to control the SPS in its roles as a multi-cycling, multi-user service accelerator. The messages are centrally generated by an IBM compatible PC/AT card and broadcast to all users of the system. At the receiving end the frames are decoded and presented to the user in the form of either an interrupt to his intelligent equipment, a hardware pulse or a short message. They are used to synchronise the SPS when used as a 450 GeV fixed target machine, a 315 GeV p-pbar collider, a 100/450 GeV pulsing-coasting machine and also as an injector for the Large Electron Positron (LEP) machine. In the future it will also be used for LEP control. Implementation details and constraints are described, as are experience to date and foreseen expansions

364

A 200 kV fast rise time, low jitter, trigger system with magnetic pulse sharpener  

International Nuclear Information System (INIS)

The DARHT Facility is being designed at Los Alamos National Laboratory to produce high resolution flash radiographs of hydrodynamic experiments. Two linear induction accelerators (LIA), each in the range of 16 to 20 MeV, will be used to produce intense bremsstrahlung X-ray pulses of short duration (60 ns flat top). Each LIA will produce a 3 kA, high brightness, electron beam using a 4 MeV injector and a series of 250 kV induction cells. Technology demonstration of key accelerator subsystems is under progress at the DARHT Integrated Test Stand (ITS). The eight inductions cells present in the ITS are driven by a Maxwell prototype Induction Cell Pulsed Power Supply (ICPPS) which provides 250 kV, 70ns pulses via four Blumleins. Each Blumlein drives two cells and is triggered using independently controlled trigger units. This turnkey DARHT Trigger System, consisting of four separate trigger units, provides 200 kV trigger pulses with low jitter and fast rise time to each of the four Blumlein coaxial spark gaps. Details of the trigger system design and results obtained during extensive testing at Maxwell are described

365

Fast-neutron Induced Reactions at the nELBE Time-of-flight Facility  

Science.gov (United States)

The compact neutron-time-of-flight facility nELBE at the superconducting electron accelerator ELBE of Helmholtz-Zentrum Dresden-Rossendorf is being rebuilt and extended with a low-background experimental hall. The neutron radiator consists of a liquid lead circuit without additional neutron moderators. The useful neutron spectrum extends from some tens of keV to about 10 MeV. nELBE is intended to deliver cross section data of fast-neutron nuclear interactions e.g. for the transmutation of nuclear waste and improvement of neutron physical simulations of innovative nuclear systems. Before the extension of the facility, the photon production cross section of 56Fe was measured with an HPGe detector and the inelastic neutron scattering cross section to the first few excited states in 56Fe was determined. The neutron total cross sections of Au and Ta were determined in the energy from 200 keV to 7 MeV in a transmission experiment.

Junghans, A. R.; Beyer, R.; Elekes, Z.; Grosse, E.; Hannaske, R.; Kögler, T.; Massarczyk, R.; Schwengner, R.; Wagner, A.

2014-05-01

366

Fast segmentation of stained nuclei in terabyte-scale, time resolved 3D microscopy image stacks.  

Science.gov (United States)

Automated analysis of multi-dimensional microscopy images has become an integral part of modern research in life science. Most available algorithms that provide sufficient segmentation quality, however, are infeasible for a large amount of data due to their high complexity. In this contribution we present a fast parallelized segmentation method that is especially suited for the extraction of stained nuclei from microscopy images, e.g., of developing zebrafish embryos. The idea is to transform the input image based on gradient and normal directions in the proximity of detected seed points such that it can be handled by straightforward global thresholding like Otsu's method. We evaluate the quality of the obtained segmentation results on a set of real and simulated benchmark images in 2D and 3D and show the algorithm's superior performance compared to other state-of-the-art algorithms. We achieve an up to ten-fold decrease in processing times, allowing us to process large data sets while still providing reasonable segmentation results. PMID:24587204

Stegmaier, Johannes; Otte, Jens C; Kobitski, Andrei; Bartschat, Andreas; Garcia, Ariel; Nienhaus, G Ulrich; Strähle, Uwe; Mikut, Ralf

2014-01-01

367

Fast Segmentation of Stained Nuclei in Terabyte-Scale, Time Resolved 3D Microscopy Image Stacks  

Science.gov (United States)

Automated analysis of multi-dimensional microscopy images has become an integral part of modern research in life science. Most available algorithms that provide sufficient segmentation quality, however, are infeasible for a large amount of data due to their high complexity. In this contribution we present a fast parallelized segmentation method that is especially suited for the extraction of stained nuclei from microscopy images, e.g., of developing zebrafish embryos. The idea is to transform the input image based on gradient and normal directions in the proximity of detected seed points such that it can be handled by straightforward global thresholding like Otsu’s method. We evaluate the quality of the obtained segmentation results on a set of real and simulated benchmark images in 2D and 3D and show the algorithm’s superior performance compared to other state-of-the-art algorithms. We achieve an up to ten-fold decrease in processing times, allowing us to process large data sets while still providing reasonable segmentation results. PMID:24587204

Stegmaier, Johannes; Otte, Jens C.; Kobitski, Andrei; Bartschat, Andreas; Garcia, Ariel; Nienhaus, G. Ulrich; Strähle, Uwe; Mikut, Ralf

2014-01-01

368

Fast Turn-Off Times Observed in Experimental 4H SiC Thyristors  

Science.gov (United States)

Room temperature measurements of the turn-off time (t(sub q)) are reported for several packaged, npnp developmental power thyristors based on 4H-type SiC and rated 400 V, 2 A. Turn-off is effected by a 50 V pulse of applied reverse voltage, from a state of a steady 1 A forward current. Plots of t(sub q) against the ramp rate (dV(sub AK)/dt) of reapplied forward voltage are presented for preset values of limiting anode-to-cathode voltage (V(sub AK,max)). The lowest t(sub q) measured was about 180 ns. A rapid rise of these t(sub q) curves was observed for values of V(sub AK,max) that are only about a fifth of the rated voltage, whereas comparative t(sub q) plots for a commercial, fast turn-off, Si-based thyristor at a proportionately reduced V(sub AK,max) showed no such behavior. Hence these SiC thyristors may have problems arising from material defects or surface passivation. The influence the R-C-D gate bypass circuit that was used is briefly discussed.

Niedra, Janis M.

2006-01-01

369

Bone response to fast-degrading, injectable calcium phosphate cements containing PLGA microparticles.  

Science.gov (United States)

Apatitic calcium phosphate cements (CPC) are frequently used to fill bone defects due to their favourable clinical handling and excellent bone response, but their lack of degradability inhibits complete bone regeneration. In order to render these injectable CaP cements biodegradable, hollow microspheres made of poly (D,L-lactic-co-glycolic) acid (PLGA) have been previously used as porogen since these microspheres were shown to be able to induce macroporosity upon degradation as well as to accelerate CPC degradation by release of acid degradation products. Recently, the capacity of PLGA microspheres to form porosity in situ in injectable CPCs was optimized by investigating the influence of PLGA characteristics such as microsphere morphology (dense vs. hollow) and end-group functionalization (acid terminated vs. end-capped) on acid production and corresponding porosity formation in vitro. The current study has investigated the in vivo bone response to CPCs containing two types of microspheres (hollow and dense) made of PLGA with two different end-group functionalizations (end capped and acid terminated). Microspheres were embedded in CPC and injected in the distal femoral condyle of New Zealand White Rabbits for 6 and 12 weeks. Histological results confirmed the excellent biocompatibility and osteoconductivity of all tested materials. Composites containing acid terminated PLGA microspheres displayed considerable porosity and concomitant bone ingrowth after 6 weeks, whereas end capped microspheres only revealed open porosity after 12 weeks of implantation. In addition, it was found that dense PLGA microspheres induced significantly more CPC degradation and bone tissue formation compared to hollow PLGA microspheres. In conclusion, it was shown that PLGA microspheres have a strong capacity to induce fast degradation of injectable CPC and concomitant replacement by bone tissue by controlled release of acid polymeric degradation products without compromising the excellent biocompatibility and osteoconductivity of the CPC matrix. PMID:21871661

Félix Lanao, Rosa P; Leeuwenburgh, Sander C G; Wolke, Joop G C; Jansen, John A

2011-12-01

370

Metabolic response to 36 hours of fasting in young men born small vs appropriate for gestational age  

DEFF Research Database (Denmark)

AIMS/HYPOTHESIS: Being born small for gestational age (SGA) is associated with an increased risk of type 2 diabetes in an affluent society, but could confer an improved chance of survival during sparse living conditions. We studied whether insulin action and other metabolic responses to prolonged fasting differed between 21 young adults born SGA and 18 matched controls born appropriate for gestational age (AGA). METHODS: A frequently sampled IVGTT and indirect calorimetry measurements were performed after a 36 h fast. Endogenous glucose production, insulin sensitivity (SI), first-phase insulin secretion and glucose effectiveness were estimated by stable isotope tracer techniques and minimal modelling. Muscle and fat biopsies were obtained after 35 h of fasting. RESULTS: During fasting, SGA individuals experienced a more pronounced decrease in serum insulin and lower plasma triacylglycerol levels compared with AGA individuals. In addition, energy expenditure decreased in SGA but increased in AGA individuals.After fasting, SGA individuals displayed lower fat oxidation than AGA individuals. SG was reduced in SGA compared with AGA individuals, whereas hepatic or whole body insulin action (SI) did not differ between groups. SGA individuals had increased muscle PPARGC1A DNA methylation. We found no differences in adipose tissue PPARGC1A DNA methylation, muscle and adipose tissue PPARGC1A mRNA expression, or muscle glycogen levels between the groups. CONCLUSION: Compared with AGA individuals, SGA individuals displayed a more energy-conserving and energy-conserving cardiometabolic response to 36 h fasting. The role of increased muscle PPARGC1A DNA methylation in mediating this response requires further study.

JØrgensen, Sine W; BrØns, Charlotte

2014-01-01

371

Synthesis of fast response crosslinked PVA-g-NIPAAm nanohydrogels by very low radiation dose in dilute aqueous solution  

International Nuclear Information System (INIS)

Nanohydrogels of poly(vinyl alcohol)-g-N-isopropylacrylamide (PVA-g-NIPAAm) are synthesized by PVA and NIPAAm dilute aqueous solution using much less radiation dose of 1–20 Gy via intramolecular crosslinking at ambient temperature. The radiation synthesis of nanohydrogels is performed in the presence of tetrakis (hydroxymethyl) phosphonium chloride (THPC) due to its rapid oxygen scavenging abilities and hydrogen peroxide (H2O2) as a source of hydroxyl radicals. The effect of radiation dose, feed composition ratio of PVA and H2O2 is investigated on swelling properties such as temperature and pH dependence of equilibrium swelling ratio as well as deswelling kinetics. Experimental data exhibit high equilibrium swelling ratio and fast response time for the synthesized nanohydrogels. The average molecular weight between crosslinks (Mc) and crosslinking density (?x) of the obtained nanohydrogels are calculated from swelling data as a function of radiation dose, H2O2 and PVA amount. Fourier transform infrared spectroscopy (FT-IR), elemental analysis of nitrogen content and thermogravimetric analysis (TGA) are used to confirm the grafting reaction. Lower critical solution temperature (LCST) is measured around 33 °C by differential scanning calorimetry (DSC) for PVA-g-NIPAAm nanohydrogels. Dynamic light scattering (DLS) data demonstrate that the increase of radiation dose leads to the decreasing in dimension of nanohydrogels. Also, rheological studies are confirmed an improvement in the mechanical properties of the nanohydrogels with increasing the radiation dose. A cytotoxicity study exhibits a good biocompatibility for the obtained nanohydrogels. The prepared nanohydrogels show fast swelling/deswelling behavior, high swelling ratio, dual sensitivity and good cytocompatibility, which may find potential applications as biomaterial. - Highlights: ? A new radiation polymerization method is offered in dilute aqueous solution.? This method provides PVA-g-NIPAAm nanohydrogels by radiation dose of 1–20 Gy. ? Using THPC and H2O2 leads to the polymerization with much less radiation dose. ? The obtained nanohydrogels exhibit fast swelling/deswelling rate. ? Nanohydrogels indicate good rheological properties and biocompatibility

372

Measurement of time-dependent fast neutron energy spectra in a depleted uranium assembly  

International Nuclear Information System (INIS)

Time-dependent neutron energy spectra in the range 0.6 to 6.4 MeV have been measured in a depleted uranium assembly. By selecting windows in the time range 0.9 to 82 ns after the beam pulse, it was possible to observe the change of the neutron energy distributions from spectra of predominantly 4 to 6 MeV neutrons to spectra composed almost entirely of fission neutrons. The measured spectra were compared to a Monte Carlo calculation of the experiment using the ENDF/B-IV data file. At times and energies at which the calculation predicted a fission spectrum, the experiment agreed with the calculation, confirming the accuracy of the neutron spectroscopy system. However, the presence of discrepancies at other times and energies suggested that there are significant inconsistencies in the inelastic cross sections in the 1 to 6 MeV range. The time response generated concurrently with the energy spectra was compared to the Monte Carlo calculation. From this comparison, and from examination of time spectra measured by other workers using 235U and 237Np fission detectors, it would appear that there are discrepancies in the ENDF/B-IV cross sections below 1 MeV. The predicted decay rates were too low below and too high above 0.8 MeV

373

A fast least-squares arrival time estimator for scintillation pulses  

International Nuclear Information System (INIS)

The true weighted least-squares (WLS) arrival time estimator for scintillation pulse detection was previously found to out-perform conventional arrival time estimators such as leading-edge and constant-fraction timers, but has limited applications because of its complexity. A new diagonalized version of the weighted least-squares (DWLS) estimator has been developed which, like the true WLS, incorporates the statistical properties of the scintillation detector. The new DWLS reduces estimator complexity at the expense of fundamental timing resolution. The advantage of the DWLS implementation is that only scalar multiplications and additions are needed instead of the matrix operations used in the true WLS. It also preserves the true WLS's ability to effectively separate piled-up pulses. The DWLS estimator has been applied to pulses which approximate the response of BGO and NaI(Tl) scintillation detectors. The timing resolution obtained with the DWLS estimator is then compared to conventional analog timers along with the Cramer-Rao lower bound on achievable timing error. The DWLS out-performs the conventional arrival time estimators but does not provide optimal performance compared to the lower bound; however, it is more robust than the true WLS estimator

374

Gamma-rays and fast neutron responses calculations for personal electronic dosimetry purpose  

Science.gov (United States)

Real-time dosimeters with small size N-type silicon diodes are proposed here for low-dose rate controls. Numerical simulations are used to predict the responses of various associated filters, neutron converters and sensors. The monitor is foreseen to work as a counter with acceptance cut-offs set on each individual pulse height. Discussions are undertaken against the minimal outline necessary to reach convenient measurement accuracies in unknown gamma-neutron fields.

Jung, M.; Teissier, C.; Siffert, P.

2001-02-01

375

Very high pressure liquid chromatography using fully porous particles: quantitative analysis of fast gradient separations without post-run times.  

Science.gov (United States)

Using a column packed with fully porous particles, four methods for controlling the flow rates at which gradient elution runs are conducted in very high pressure liquid chromatography (VHPLC) were tested to determine whether reproducible thermal conditions could be achieved, such that subsequent analyses would proceed at nearly the same initial temperature. In VHPLC high flow rates are achieved, producing fast analyses but requiring high inlet pressures. The combination of high flow rates and high inlet pressures generates local heat, leading to temperature changes in the column. Usually in this case a post-run time is input into the analytical method to allow the return of the column temperature to its initial state. An alternative strategy involves operating the column without a post-run equilibration period and maintaining constant temperature variations for subsequent analysis after conducting one or a few separations to bring the column to a reproducible starting temperature. A liquid chromatography instrument equipped with a pressure controller was used to perform constant pressure and constant flow rate VHPLC separations. Six replicate gradient separations of a nine component mixture consisting of acetophenone, propiophenone, butyrophenone, valerophenone, hexanophenone, heptanophenone, octanophenone, benzophenone, and acetanilide dissolved in water/acetonitrile (65:35, v/v) were performed under various experimental conditions: constant flow rate, two sets of constant pressure, and constant pressure operation with a programmed flow rate. The relative standard deviations of the response factors for all the analytes are lower than 5% across the methods. Programming the flow rate to maintain a fairly constant pressure instead of using instrument controlled constant pressure improves the reproducibility of the retention times by a factor of 5, when plotting the chromatograms in time. PMID:24296292

Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Beaver, Lois Ann; Guiochon, Georges

2014-01-10

376

Acetobacter aceti fast identification by Real Time PCR in spoiled wine samples  

Directory of Open Access Journals (Sweden)

Full Text Available Wine is a beverage that made from grape berries. However, without beneficial bacteria, we would not produce good wine. But very often wines contain acetic acid bacteria, which are undesirable in winemaking process. Acetic acid bacteria as known as a vinegar bacteria are Gram-negative, aerobic, rod-shaped and ubiquitous bacteria. This study was focused on species of acetic acid bacteria, specifically Acetobacter aceti that make spoilage in wine.The aim of our study was the identification of Acetobacter aceti in spoiled red wine samples, with plate dilution method on agar plates and using sensitive Real-time PCR (qPCR method. We cultivated Acetobacter aceti on GYC agar at 30°C, 48h. The one of main objective in the present work was the test fast, sensitive and reliable technique such as quantitative Real-time PCR and detecting the presence of Acetobacter aceti in wine samples with positive Acetobacteraceti control on amplification plot and melting curve. The next objective before  qPCR analysis was DNA extraction from wine samples incubated for one week at 28°C aerobically. We used five different red wine samples for this experiment: Alibernet 2013, Blaufränkisch 2013, Cabernet Sauvignon 2013, Dunaj 2012 and Saint-Laurent 2012. Next we extracted DNA from wine samples and from pure Acetobacter aceti CCM 3620T strain purchased from Czech collection of microorganisms in Brno. Susceptibility ofAcetobacter aceti was varied in different isolates from 102 to 107 CFU.mL-1. The number of Acetobacter cells on GYC medium ranged from 4.05 to 4.83log CFU.mL-1 in differentwine samples.The higher number of Acetobacter cells (4.83 log CFU.mL-1 was found in Cabernet Sauvignon 2013 wine.

Attila Kántor

2014-11-01

377

Creating fast flow channels in paper fluidic devices to control timing of sequential reactions.  

Science.gov (United States)

This paper reports the development of a method to control the flow rate of fluids within paper-based microfluidic analytical devices. We demonstrate that by simply sandwiching paper channels between two flexible films, it is possible to accelerate the flow of water through paper by over 10-fold. The dynamics of this process are such that the height of the liquid is dependent on time to the power of 1/3. This dependence was validated using three different flexible films (with markedly different contact angles) and three different fluids (water and two silicon oils with different viscosities). These covered channels provide a low-cost method for controlling the flow rate of fluid in paper channels, and can be added following printing of reagents to control fluid flow in selected fluidic channels. Using this method, we redesigned a previously published bidirectional lateral flow pesticide sensor to allow more rapid detection of pesticides while eliminating the need to run the assay in two stages. The sensor is fabricated with sol-gel entrapped reagents (indoxyl acetate in a substrate zone and acetylcholinesterase, AChE, in a sensing zone) present in an uncovered "slow" flow channel, with a second, covered "fast" channel used to transport pesticide samples to the sensing region through a simple paper-flap valve. In this manner, pesticides reach the sensing region first to allow preincubation, followed by delivery of the substrate to generate a colorimetric signal. This format results in a uni-directional device that detects the presence of pesticides two times faster than the original bidirectional sensors. PMID:23079674

Jahanshahi-Anbuhi, Sana; Chavan, Puneet; Sicard, Clémence; Leung, Vincent; Hossain, S M Zakir; Pelton, Robert; Brennan, John D; Filipe, Carlos D M

2012-12-01

378

Fast response organic light-emitting diode for visible optical communication  

Science.gov (United States)

We examined fast response organic light-emitting diodes (OLEDs) for new applications of visible optical communications. For the practical use in this field, the fast transmission speed of OLEDs is required to be used in many applications, but the low carrier mobility of organic materials and the long fluorescence lifetime (FL) organic emitting materials limit the transmission speed of OLEDs. Therefore, we investigated the influence of the FL on transient properties of photoluminescence (PL), which were evaluated by the frequency dependence of PL intensity excited by a modulated violet laser diode. The FLs of several organic emitting materials were also measured, and we found the clear relationship between the FL and the transient properties of PL intensity. The fastest cutoff frequency of PL intensity was achieved 160 MHz utilizing short FL material, 1,4-bis[2-[4-[N,N-di(ptolyl)amino]phenl]vinyl]benzene. We also investigated another way to increase the transmission speed utilizing a semiconductor-organic multilayer structure, of which ZnS was used as an electron transport layer. The maximum cutoff frequency of this device was achieved 20.3 MHz, while that of the organic multilayer structure was 8.7 MHz at a sine wave voltage of 7 V and a bias voltage of 5 V. This result indicates that the high carrier mobility of the ZnS layer causes the increase in the transmission speed of OLEDs. We demonstrated one institutive demonstrator module of visible optical communications, which consisted of the transceiver module with an OLED and the pen-type receiver module with a photo-diode at a point. The movie files was transmitted at a speed of 230 kbps, when the point of a pen-type receiver module approaches the emitting area of an OLED. Furthermore, the pseudo-random signal with 1Mbps was also transmitted with this visible optical communication system. Such a system enables to connect between transceiver and receiver module without precious alignment because of the large emitting area of OLEDs. So, we think that many people, from children to aged people, are easy to get information from OLEDs without being aware of using optical communications. Furthermore, the communication field is limited near the emitting area of an OLED, resulting in a safe data transmission.

Fukuda, Takeshi; Taniguchi, Yoshio

2008-02-01

379

Reaction-time response of a large commercial aircraft  

International Nuclear Information System (INIS)

The reaction-time response of a large commercial aircraft is defined. The aircraft is examined as a thin-walled tubular missile. The impact is assumed soft, and the target's effect on the reaction-time response is neglected. The reaction-time response is defined assuming a normal impact on a rigid wall. The reaction-time response is defined with the analytical Riera method and with the numerical explicit finite element method. The Riera force history is solved with the finite difference method. For the finite element method, two codes are used: Abaqus/Explicit and LS-DYNA. Focus is on the sensitivity study of the used methods. The outer shell of the aircraft is modeled, and an approximation for the mass-distribution is made. Sensitivity to modeling assumptions is studied in order to get information on the adequacy of modeling. The results indicate relatively small sensitivity to modeling assumptions. The wings should be modeled more accurately in order to obtain the dominant frequency response in global structural analysis. (author)

380

Sensors Response Time validation using Dimensionality Reduction Techniques  

Directory of Open Access Journals (Sweden)

Full Text Available The temperature and Pressure sensors play a vital role in Nuclear Power Plants (NPP. The Rosemount temperature sensor helps to produce the exact temperature and pressure measurement of the nuclear power plant. The sensors that supply real data must respond quickly to the safety systems of NPP. In this paper, first the Dimensionality of the Original dataset is reduced by using Principal Component Analysis (PCA, Independent Component Analysis (ICA and Singular Value Decomposition (SVD. Finally the sensors Response Time is computed and compared with original response time.

S. Gayathri

2013-04-01

 
 
 
 
381

Research on a Fast Delivery Production System: Just-in-time production system  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, we analyzed calling the age to product or service for consumer demand living in the word. We come to a conclusion that speed or time is the key factors for enterpriser for competing intensely. So, the paper proposes JIT system achieve the tasks. Later, we address thoroughly the meaning of Just-in-time production system from speed and time angles and present two goals ultimate goal and the supporting goals implementation successfully. According to goal, this paper analyzed that implementing JIT should be achieved requires and carry out approaches. At last, this paper provided that JIT contribute benefits and causes to problem. Nonetheless, JIT is a robust production system for manufacturer and consumer. Moreover, I believe that it advent and it will be a main stream of a fluid production system for the future.
Key words: just-in-time production system; fast delivery; continue quality improvement; manufacturing cells
Résumé: Dans cette mémoire, nous analysons la vocation de l’âge à produire ou à servir pour la vie de la demande consommatrice dans le monde. Nous venons à une conclusion que la vitesse ou le temps est les facteurs clés en faveur de l’entrepreneur dans le but de rivaliser profondément. Donc, la mémoire propose le système JIT accomplit les tâches. Ensuite, nous adressons à fond le sens du système producteur JIT de la vitesse et les angles de temps et présentons deux buts, but ultime et l’implémentation des buts soutenant successivement. D’après le but, cette mémoire analyse que l’implémentation JIT doit être accomplie les demandes et exécuter les propositions. Enfin, cette mémoire fournit que le JIT contribue les avantages et les causes au problème. Malgré tout, JIT est un système robuste producteur pour les fabricants et les consommateurs. En plus, je crois qu’il se réalisera et sera un torrent d’un système producteur fluide pour l’avenir.
Mots-Clés: Système producteur JIT ; livraison rapide ; amélioration qualitative continuelle; cellule fabricante

Cai-feng LI

2009-06-01

382

Some Measurements of Fast Reactor Spectra by the Time-of-Flight Technique Using a Pulsed Neutron Source  

International Nuclear Information System (INIS)

The zero-energy fast reactor VERA is equipped with a pulsed neutron source and a 50-m neutron flight path and these facilities have been used for time-of-flight neutron spectrometry in the energy range 100 eV to 50 keV. The results are discussed and are compared with calculated values. (author)

383

A Fast Topological Trigger for Real Time Analysis of Nanosecond Phenomena; Opening the Gamma Ray Window to Our Universe  

Energy Technology Data Exchange (ETDEWEB)

This work was to enable the development of a proof-of-principle nanosecond trigger system that is designed to perform a real time analysis of fast Cherenkov light flashes from air showers. The basic building blocks of the trigger system have been designed and constructed, and a real world system is now operating in the VERITAS experiment.

Krennrich, Frank [Iowa State University

2013-09-24

384

Gamma-ray fast-timing coincidence measurements from the 18O+18O fusion–evaporation reaction using a mixed LaBr3-HPGe array  

International Nuclear Information System (INIS)

We report on a gamma-ray coincidence analysis using a mixed array of hyperpure germanium and cerium-doped lanthanum tri-bromide (LaBr3:Ce) scintillation detectors to study nuclear electromagnetic transition rates in the pico-to-nanosecond time regime in 33,34P and 33S following fusion–evaporation reactions between an 18O beam and an isotopically enriched 18O implanted tantalum target. Energies from decay gamma-rays associated with the reaction residues were measured in event-by-event coincidence mode, with the measured time difference information between the pairs of gamma-rays in each event also recorded using the ultra-fast coincidence timing technique. The experiment used the good full-energy peak resolution of the LaBr3:Ce detectors coupled with their excellent timing responses in order to determine the excited state lifetime associated with the lowest lying, cross-shell, I?=4? “intruder” state previously reported in the N=19 isotone 34P. The extracted lifetime is consistent with a mainly single-particle M2 multipolarity associated with a f7/2?d5/2 single particle transition. - Highlights: ? Half-life measurements of nuclear states. ? Using fast-timing properties of (LaBr3:Ce) scintillator detectors. ? (LaBr3:Ce) scintillation detectors have an excellent timing resolution.

385

Association of consecutive Pi2-Ps6 band pulsations with earthward fast flows in the plasma sheet in response to IMF variations  

Science.gov (United States)

11 March 2009, the H component had four consecutive bay-like variations accompanied by positive and negative deflections in the D component across the Atlantic like those affected by the substorm current wedge formation. A train of pulsations with a frequency range 2-10 mHz (referred to as Pi2-Ps6 band), sensed by Time History of Events and Macroscale Interactions during Substorms (THEMIS)/Canadian Array for Real-time Investigations of Magnetic Activity (CARISMA) magnetometers, had clearly three consecutive Pi2s followed by a Ps6 at low latitudes, but first Pi2 and then Ps6 at high latitudes mixed with large-amplitude Ps6 at midlatitudes. The geostationary orbit magnetometers sensed similar magnetic perturbations. THEMIS probes first observed earthward fast flows, magnetic dipolarizations, and modulated energetic particle fluxes at ~ XGSM -9.2 RE, then at ~ XGSM -7.5 RE for Pi2 and at ~ XGSM -18.0 RE only for Ps6. They appeared during a very quiet period for northward interplanetary magnetic field (IMF) with a clock angle variation of low to high and then low. The H spectrum shows two harmonic frequencies ~2-4 mHz and ~8-10 mHz but the D spectrum one dominant frequency ~2-4 mHz. Pi2 can result from a combination of fast magnetospheric and plasmaspheric cavity resonances and Ps6 from a fast magnetospheric cavity resonance. The surface waves at the interface separating braking earthward fast flows from the ambient plasma convection region could lead to large-amplitude Ps6 at midlatitudes. Hence, consecutive Pi2-Ps6 band pulsations can be associated with earthward fast flows in the plasma sheet, expectedly driven by magnetotail reconnection, respectively, in the near-Earth region and the distant Earth one in response to IMF variations as in the two-neutral-point model.

Cheng, Ching-Chang; Mann, Ian R.; Baumjohann, Wolfgang

2014-05-01

386

Effect of the fissile bead's and thermocouple wires' sizes on the response time of a fission couple  

Science.gov (United States)

The fission couple is proposed as a fast response miniature neutron detector in the measurement of time dependent energy depositions within the fissile material based on theoretical analysis, but the response time of a fission couple is relatively slow in practice. The time lag originated from heat transfer process was demonstrated to be the dominating factor by theoretical simulations and experimental verification in this paper. The response of a fission couple as a function of the bead size and the thermocouple wires' sizes are simulated using ANSYS workbench. The decrease of wires' diameter results in the decrease of response time, and the increase of bead's diameter leads to a slight increase of response time. During a pulse heating transient in the fuel of Chinese Fast Burst Reactor II with a FWHM of 181?s, the time lag originated from heat transfer process is about tens of microseconds for the peaks of the change rate of temperature, and is of the order of milliseconds to achieve 85% of the temperature rise for a typical fission couple with a ? 1 mm fissile bead and two ? 0.05 mm thermocouple wires. The results obtained provide foundation for the optimization of fission couples.

Liang, Wenfeng; Lu, Yi; Li, Meng; Fan, Xiaoqiang; Lu, Wei

2014-05-01

387

Exploiting Noisy Early Time Response Using the Half Fourier Transform  

Science.gov (United States)

We present a new technique for estimating the parameters of damped sinusoids utilizing both early and late time transient scattering data contaminated by noise. Transient scattering responses are composed of damped sinusoids at late times and impulse-like components at early times. In this study the entire noisy time domain response is used to extract the signal parameters of interest. The half Fourier transform (HFT) is used to analyze the data for parameter identification. Impulse or Gaussian-like pulses can be easily separated from the damped exponentials in the HFT domain, as they have similar functional representations. Results from several examples show that the new technique is applicable for noisy signals that are composed of damped exponentials and pulse-like components.

Jang, S.; Sarkar, T. K.; Salazar-Palma, M.; Baum, C. E.

388

Time-resolved observation of fast domain-walls driven by vertical spin currents in short tracks  

International Nuclear Information System (INIS)

We present time-resolved measurements of the displacement of magnetic domain-walls (DWs) driven by vertical spin-polarized currents in track-shaped magnetic tunnel junctions. In these structures, we observe very high DW velocities (600?m/s) at current densities below 107?A/cm2. We show that the efficient spin-transfer torque combined with a short propagation distance allows avoiding the Walker breakdown process and achieving deterministic, reversible, and fast (?1?ns) DW-mediated switching of magnetic tunnel junction elements, which is of great interest for the implementat