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1

Control of Spontaneous Emission via Reservoir Engineering  

E-print Network

We study two distinct multi-level atomic models in which one transition is coupled to a Markovian reservoir, while another linked transition is coupled to a non-Markovian reservoir. We show that by choosing appropriately the density of modes of the non-Markovian reservoir the spontaneous emission to the Markovian reservoir is greatly altered. The existence of `dark lines' in the spontaneous emission spectrum in the Markovian reservoir due to the coupling to specific density of modes of the non-Markovian reservoir is also predicted.

Paspalakis, E; Knight, P L

1999-01-01

2

Controlling spontaneous emission in bioreplica photonic crystals  

NASA Astrophysics Data System (ADS)

Sophisticated methods have been created by nature to produce structure-based colors as a way to address the need of a wide variety of organisms. This pallet of available structures presents a unique opportunity for the investigation of new photonic crystal designs. Low-temperature sol-gel biotemplating methods were used to transform a single biotemplate into a variety of inorganic oxide structures. The density of optical states was calculated for a diamond-based natural photonic crystal, as well as several structures templated from it. Calculations were experimentally probed by spontaneous emission studies using time correlated single photon counting measurements.

Jorgensen, Matthew R.; Butler, Elizabeth S.; Bartl, Michael H.

2012-04-01

3

Room temperature continuous wave operation and controlled spontaneous emission in  

E-print Network

InAsP photonic crystal point defect nanocavity at room temperature," Appl. Phys. Lett. 85, 3989-3991 (2004). 17, as high as 106 K/W, has prevented continuous-wave operation at room temperature. The present paper reportsRoom temperature continuous wave operation and controlled spontaneous emission in ultrasmall

Baba, Toshihiko

4

Controlled spontaneous emission in erbium-doped microphotonic materials  

Microsoft Academic Search

Erbium is a rare-earth metal that, when incorporated in a solid, can emit light at a wavelength of 1.5 ?m. It plays a key role in current day telecommunication technology as the principle ingredient of optical fiber amplifiers. In this thesis the control of the Er spontaneous emission in three different types of microphotonic materials is described.\\u000a\\u000a\\u000aPart I of

Jeroen Kalkman

2005-01-01

5

Ultrafast non-local control of spontaneous emission.  

PubMed

The radiative interaction of solid-state emitters with cavity fields is the basis of semiconductor microcavity lasers and cavity quantum electrodynamics (CQED) systems. Its control in real time would open new avenues for the generation of non-classical light states, the control of entanglement and the modulation of lasers. However, unlike atomic CQED or circuit quantum electrodynamics, the real-time control of radiative processes has not yet been achieved in semiconductors because of the ultrafast timescales involved. Here we propose an ultrafast non-local moulding of the vacuum field in a coupled-cavity system as an approach to the control of radiative processes and demonstrate the dynamic control of the spontaneous emission (SE) of quantum dots (QDs) in a photonic crystal (PhC) cavity on a ?200 ps timescale, much faster than their natural SE lifetimes. PMID:25218324

Jin, Chao-Yuan; Johne, Robert; Swinkels, Milo Y; Hoang, Thang B; Midolo, Leonardo; van Veldhoven, Peter J; Fiore, Andrea

2014-11-01

6

Controlling the dynamics of spontaneous emission from quantum dots by photonic crystals  

Microsoft Academic Search

Control of spontaneously emitted light lies at the heart of quantum optics. It is essential for diverse applications ranging from miniature lasers and light-emitting diodes, to single-photon sources for quantum information, and to solar energy harvesting. To explore such new quantum optics applications, a suitably tailored dielectric environment is required in which the vacuum fluctuations that control spontaneous emission can

Peter Lohdahl; A. Floris van Driel; Ivan S. Nikolaev; Arie Irman; Karin Overgaag; Daniël Vanmaekelbergh; Willem L. Vos

2004-01-01

7

Two-dimensional sub-half-wavelength atom localization via controlled spontaneous emission.  

PubMed

We propose a scheme for two-dimensional (2D) atom localization based on the controlled spontaneous emission, in which the atom interacts with two orthogonal standing-wave fields. Due to the spatially dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the resulting spontaneously emission spectrum. The phase sensitive property of the atomic system leads to quenching of the spontaneous emission in some regions of the standing-waves, which significantly reduces the uncertainty in the position measurement of the atom. We find that the frequency measurement of the emitted light localizes the atom in half-wavelength domain. Especially the probability of finding the atom at a particular position can reach 100% when a photon with certain frequency is detected. By increasing the Rabi frequencies of the driving fields, such 2D sub-half-wavelength atom localization can acquire high spatial resolution. PMID:22273975

Wan, Ren-Gang; Zhang, Tong-Yi

2011-12-01

8

Controlling the spontaneous emission rate of monolayer MoS2 in a photonic crystal nanocavity  

NASA Astrophysics Data System (ADS)

We report on controlling the spontaneous emission (SE) rate of a molybdenum disulfide (MoS2) monolayer coupled with a planar photonic crystal (PPC) nanocavity. Spatially resolved photoluminescence (PL) mapping shows strong variations of emission when the MoS2 monolayer is on the PPC cavity, on the PPC lattice, on the air gap, and on the unpatterned gallium phosphide substrate. Polarization dependences of the cavity-coupled MoS2 emission show a more than 5 times stronger extracted PL intensity than the un-coupled emission, which indicates an underlying cavity mode Purcell enhancement of the MoS2 SE rate exceeding a factor of 70.

Gan, Xuetao; Gao, Yuanda; Fai Mak, Kin; Yao, Xinwen; Shiue, Ren-Jye; van der Zande, Arend; Trusheim, Matthew E.; Hatami, Fariba; Heinz, Tony F.; Hone, James; Englund, Dirk

2013-10-01

9

Controlling the dynamics of spontaneous emission from quantum dots by photonic crystals  

NASA Astrophysics Data System (ADS)

Control of spontaneously emitted light lies at the heart of quantum optics. It is essential for diverse applications ranging from miniature lasers and light-emitting diodes, to single-photon sources for quantum information, and to solar energy harvesting. To explore such new quantum optics applications, a suitably tailored dielectric environment is required in which the vacuum fluctuations that control spontaneous emission can be manipulated. Photonic crystals provide such an environment: they strongly modify the vacuum fluctuations, causing the decay of emitted light to be accelerated or slowed down, to reveal unusual statistics, or to be completely inhibited in the ideal case of a photonic bandgap. Here we study spontaneous emission from semiconductor quantum dots embedded in inverse opal photonic crystals. We show that the spectral distribution and time-dependent decay of light emitted from excitons confined in the quantum dots are controlled by the host photonic crystal. Modified emission is observed over large frequency bandwidths of 10%, orders of magnitude larger than reported for resonant optical microcavities. Both inhibited and enhanced decay rates are observed depending on the optical emission frequency, and they are controlled by the crystals' lattice parameter. Our experimental results provide a basis for all-solid-state dynamic control of optical quantum systems.

Lodahl, Peter; Floris van Driel, A.; Nikolaev, Ivan S.; Irman, Arie; Overgaag, Karin; Vanmaekelbergh, Daniël; Vos, Willem L.

2004-08-01

10

Sub-half-wavelength atom localization via bichromatic phase control of spontaneous emission  

NASA Astrophysics Data System (ADS)

We show that the bichromatic phase control of the spontaneous emission spectrum leads to the sub-half-wavelength atom localization. We consider a three-level ?-type atom interacting with a bichromatic coupling field and a bichromatic probe field with equal frequency difference. One component of the bichromatic coupling field is a standing-wave field with position dependent Rabi frequency. When the spontaneous emitted photons are detected, the atom is localized in either of the two half-wavelength regions with 50% probability by the variation of the difference between the relative phases of the two bichromatic fields.

Xu, Jun; Hu, Xiang-Ming

2007-06-01

11

Novel spontaneous emission control using 3-dimensional photonic bandgap crystal cavity  

Microsoft Academic Search

A novel surface-emitting-laser diode consisting of a 3-dimensional (3D) photonic-bandgap-crystal cavity (PBGC) is proposed. Spontaneous emission is controlled so as to radiate into the lasing direction with a narrow radiation angle by introducing a plane phase shift region into the crystal. We analyze the radiation mode density in the PBGC-cavity with a plane-wave method by using a 3D-diamond photonic crystal

Hideki Hirayama; Tetsuko Hamano; Yoshinobu Aoyagi

1998-01-01

12

Controlling the spontaneous emission rate of monolayer MoS[subscript 2] in a photonic crystal nanocavity  

E-print Network

We report on controlling the spontaneous emission (SE) rate of a molybdenum disulfide (MoS[subscript 2]) monolayer coupled with a planar photonic crystal (PPC) nanocavity. Spatially resolved photoluminescence (PL) mapping ...

Gan, Xuetao

13

Continuously tunable sub-half-wavelength localization via coherent control of spontaneous emission  

NASA Astrophysics Data System (ADS)

We propose a continuously tunable method of sub-half-wavelength localization via the coherent control of the spontaneous emission of a four-level Y-type atomic system, which is coupled to three strong coupling fields including a standing-wave field together with a weak probe field. It is shown that the sub-half-wavelength atomic localization is realized for both resonance and off-resonance cases. Furthermore, by varying the probe detuning in succession, the positions of the two localization peaks are tuned continuously within a wide range of probe field frequencies, which provides convenience for the realization of sub-half-wavelength atomic localization experimentally.

Wang, Fei; Gong, Cheng; Tan, Xin-Yu; Shi, Wen-Xing

2012-11-01

14

Switching Control of Spontaneous Emission by Polarized Atoms in Two-Dimensional Photonic Crystals  

SciTech Connect

We calculate the lifetime distribution function of an assembly of polarized atoms in two-dimensional (2D) photonic crystals (PCs) at different polarization orientations of atomic dipole moments. We reveal a switching effect of atomic spontaneous emission (SE) and find a significant change of atomic lifetime, up to a factor of 33, by tuning the polarized orientation of the atoms. These observations suggest that the tuning of the polarized orientation of atoms provides a new way for the effective control of atomic SE processes in 2D PCs.

Zhou Yunsong; Wang Fuhe [Department of Physics, Capital Normal University, Beijing 100037 (China); Wang Xuehua [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Gu Benyuan [Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

2006-03-17

15

Coherent control of spontaneous emission near a photonic band edge: A qubit for quantum computation  

NASA Astrophysics Data System (ADS)

We demonstrate the coherent control of spontaneous emission for a three-level atom located within a photonic band-gap structure with one resonant frequency near the edge of the photonic band gap. Spontaneous emission from the three-level atom can be totally suppressed or strongly enhanced depending on the relative phase between the steady-state control laser coupling the two upper levels and the pump laser pulse used to create an excited state of the atom in the form of a coherent superposition of the two upper levels. Unlike the free-space case, the steady-state inversion of the atomic system is strongly dependent on the externally prescribed initial conditions. This nonzero steady-state population is achieved by virtue of the localization of light in the vicinity of the emitting atom. It is robust to decoherence effects provided that the Rabi frequency of the control laser field-atom interaction exceeds the rate of dephasing interactions. As a result, such a system may be relevant for a single-atom, phase-sensitive, optical memory device on the atomic scale. The protected electric dipole within the photonic band gap provides a basis for a qubit to encode information for quantum computations.

Woldeyohannes, Mesfin; John, Sajeev

1999-12-01

16

Coherent Control of Spontaneous Emission near a Photonic Band Edge: A Single-Atom Optical Memory Device  

NASA Astrophysics Data System (ADS)

We demonstrate coherent control of spontaneous emission from a three-level atom with one resonant frequency near the edge of a photonic band gap. As a result of quantum interference and photon localization, spontaneous emission can be totally suppressed or strongly enhanced depending on the relative phase between the control and pump laser fields. The fractionalized steady state inversion of the atom depends sensitively on the initial conditions, suggesting the possibility of a phase-sensitive, optical memory device on the atomic scale.

Quang, Tran; Woldeyohannes, Mesfin; John, Sajeev; Agarwal, Girish S.

1997-12-01

17

Controlling spontaneous emission of a two-level atom by hyperbolic metamaterials  

E-print Network

Within the frame of quantum optics we analyze the properties of spontaneous emission of two-level atom in media with indefinite permittivity tensor where the geometry of the dispersion relation is characterized by an ellipsoid or a hyperboloid(hyperbolic medium). The decay rate is explicitly given with the orientation of the dipole transition matrix element taken into account. It indicates that for the ellipsoid case the intensity of the photons coupled into different modes can be tuned by changing the direction of the matrix element and for the hyperboloid case it is found that spontaneous emission in hyperbolic medium can be dramatically enhanced compared to the dielectric background. Moreover, spontaneous emission exhibit the strong directivity and get the maximum in the asymptote direction.

Zheng Liu; Wei Li; Xunya Jiang

2012-03-03

18

Controlling the Spontaneous Emission Rate of Single Quantum Dots in a Two-Dimensional Photonic Crystal  

Microsoft Academic Search

We observe large spontaneous emission rate modification of individual InAs quantum dots (QDs) in a 2D photonic crystal with a modified, high-Q single-defect cavity. Compared to QDs in a bulk semiconductor, QDs that are resonant with the cavity show an emission rate increase of up to a factor of 8. In contrast, off-resonant QDs indicate up to fivefold rate quenching

Dirk Englund; David Fattal; Edo Waks; Glenn Solomon; Bingyang Zhang; Toshihiro Nakaoka; Yasuhiko Arakawa; Yoshihisa Yamamoto; Jelena Vuckovic

2005-01-01

19

Quenching of spontaneous emission through interference of incoherent pump processes  

E-print Network

controllable handle in manipulating the spontaneous emission to such an extent that, under certain conditions, complete quenching of spontaneous emission is possible. We also show that even the interference between the decay channels, which is considered a key...

Kapale, KT; Scully, Marlan O.; Zhu, S. Y.; Zubairy, M. Suhail

2003-01-01

20

Control of spontaneous emission from a driven five-level atom in a photonic-band-gap reservoir  

NASA Astrophysics Data System (ADS)

We investigate the spontaneous emission properties of a five-level atom driven by a microwave field, where the two transitions are coupled to a double-band photonic-band-gap reservoir. The effects of the band-edge positions and the Rabi frequency of the microwave field on the emission spectrum are discussed. It is found that several interesting phenomena in spontaneous emission spectra such as spectral-line enhancement, spectral-line elimination, and fluorescence quenching can be controlled simply by adjusting the Rabi frequency of the driving field and the transition frequency detunings from band edges. These phenomena originate from quantum interference induced by band-edge modes and the driving field.

Liu, Ronggang

2014-05-01

21

Controlling the Spontaneous Emission Rate of Single Quantum Dots in a 2D Photonic Crystal  

E-print Network

We observe large spontaneous emission rate modification of individual InAs Quantum Dots (QDs) in 2D a photonic crystal with a modified, high-Q single defect cavity. Compared to QDs in bulk semiconductor, QDs that are resonant with the cavity show an emission rate increase by up to a factor of 8. In contrast, off-resonant QDs indicate up to five-fold rate quenching as the local density of optical states (LDOS) is diminished in the photonic crystal. In both cases we demonstrate photon antibunching, showing that the structure represents an on-demand single photon source with pulse duration from 210 ps to 8 ns. We explain the suppression of QD emission rate using Finite Difference Time Domain (FDTD) simulations and find good agreement with experiment.

Dirk Englund; David Fattal; Edo Waks; Glenn Solomon; Bingyang Zhang; Toshihiro Nakaoka; Yasuhiko Arakawa; Yoshihisa Yamamoto; Jelena Vuckovic

2005-01-18

22

Quenching of spontaneous emission through interference of incoherent pump processes  

SciTech Connect

We investigate the steady-state spontaneous emission of a V-type three-level atom, with the coherence between the two upper levels modified and controlled via incoherent pumping to a fourth auxiliary level. The external pumping gives us an easily controllable handle in manipulating the spontaneous emission to such an extent that, under certain conditions, complete quenching of spontaneous emission is possible. We also show that even the interference between the decay channels, which is considered a key requirement in spontaneous emission quenching through quantum interference, is not essential to achieve near 100% trapping and almost complete suppression of spontaneous emission. Thus we provide a scheme for spontaneous emission quenching which can be easily realized experimentally.

Kapale, Kishore T. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Scully, Marlan O. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany); Zhu Shiyao [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Department of Physics, Hong Kong Baptist University, Hong Kong (China); Zubairy, M. Suhail [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Department of Electronics, Quaid-i-Azam University, Islamabad (Pakistan)

2003-02-01

23

Spontaneous Photon Emission in Cavities  

NASA Astrophysics Data System (ADS)

We investigate spontaneous photon emission processes of two-level atoms in parabolic and ellipsoidal cavities thereby taking into account the full multimode scenario. In particular, we calculate the excitation probabilities of the atoms and the energy density of the resulting few-photon electromagnetic radiation field by using semiclassical methods for the description of the multimode scenario. Based on this approach photon path representations are developed for relevant transition probability amplitudes which are valid in the optical frequency regime where the dipole and the rotating-wave approximations apply. Comparisons with numerical results demonstrate the quality of these semiclassical results even in cases in which the wave length of a spontaneously emitted photon becomes comparable or even larger than characteristic length scales of the cavity. This is the dynamical regime in which diffraction effects become important so that geometric optical considerations are typically not applicable.

Alber, G.; Griebe, N.

2014-09-01

24

Inhibited spontaneous emission in solid-state physics and electronics  

Microsoft Academic Search

It has been recognized for some time that the spontaneous emission by atoms is not necessarily a fixed and immutable property of the coupling between matter and space, but that it can be controlled by modification of the properties of the radiation field. This is equally true in the solid state, where spontaneous emission plays a fundamental role in limiting

Eli Yablonovitch

1987-01-01

25

Cavity enhanced rephased amplified spontaneous emission  

E-print Network

Amplified spontaneous emission is usually treated as an incoherent noise process. Recent theoretical and experimental work using rephasing optical pulses has shown that rephased amplified spontaneous emission (RASE) is a potential source of wide bandwidth time-delayed entanglement. Due to poor echo efficiency the plain RASE protocol doesn't in theory achieve perfect entanglement. Experiments done to date show a very small amount of entanglement at best. Here we show that rephased amplified spontaneous emission can, in principle, produce perfect multimode time-delayed two mode squeezing when the active medium is placed inside a Q-switched cavity.

Lewis A Williamson; Jevon J Longdell

2014-03-26

26

Spontaneous emission within metal-clad microcavities  

NASA Astrophysics Data System (ADS)

We present experimental results that explore the degree to which metal-clad microcavities may alter the spontaneous emission rate of a fluorescent species embedded within the cavity. We examine the role of the reflectivity and loss of the mirrors in determining the modified decay rate by altering the thickness of one of the metal mirrors. We show that despite losses arising from the metallic mirrors, metal-clad microcavities may still significantly modify the spontaneous emission rate of the embedded emitter.

Worthing, P. T.; Barnes, W. L.

1999-07-01

27

Control of the spontaneous emission from a single quantum dash using a slow-light mode in a two-dimensional photonic crystal on a Bragg reflector  

SciTech Connect

We demonstrate the coupling of a single InAs/InP quantum, emitting around 1.55 {mu}m, to a slow-light mode in a two-dimensional photonic crystal on Bragg reflector. These surface addressable 2.5D photonic crystal band-edge modes present the advantages of a vertical emission and the mode area and localization may be controlled, leading to a less critical spatial alignment with the emitter. An increase in the spontaneous emission rate by a factor of 1.5-2 is measured at low temperature and is compared to the Purcell factor predicted by three-dimensional time-domain electromagnetic simulations.

Chauvin, N.; Fiore, A. [COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, NL-5600 MB Eindhoven (Netherlands); Nedel, P.; Seassal, C.; Ben Bakir, B.; Letartre, X.; Gendry, M.; Viktorovitch, P. [Universite de Lyon, Institut des Nanotechnologies de Lyon (INL), UMR CNRS 5270, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, F-69134 Ecully (France)

2009-07-15

28

Blue shift of spontaneous emission in hyperbolic metamaterial.  

PubMed

Spontaneous emission is one of the most fundamental quantum phenomena in optics. Following the seminal work of Purcell and in agreement with the Fermi's Golden Rule, its rate can be controlled with the photonic density of states (PDOS). In recent years, this effect has been demonstrated in metamaterials with hyperbolic dispersion--highly anisotropic composite materials, which have a broad-band singularity of the density of photonic states. At this time, we show that hyperbolic metamaterials can control spontaneous emission spectra as well. Experimentally, DCM laser dye has been embedded into lamellar metal/dielectric metamaterial. The observed 18?nm blue shift of emission is explained by strong dispersion of the density of photonic states. On the other hand, practically no spectral shift has been observed in the excitation spectra of the same dye. This suggests that the effect of PDOS on spontaneous emission is very different from its effect on excitation and absorption. PMID:24957679

Gu, Lei; Tumkur, T U; Zhu, G; Noginov, M A

2014-01-01

29

Cavity enhanced rephased amplified spontaneous emission  

NASA Astrophysics Data System (ADS)

Amplified spontaneous emission is usually treated as an incoherent noise process. Recent theoretical and experimental work using rephasing optical pulses has shown that rephased amplified spontaneous emission (RASE) is a potential source of wide bandwidth time-delayed entanglement. Due to poor echo efficiency the plain RASE protocol does not in theory achieve perfect entanglement. Experiments done to date show a very small amount of entanglement at best. Here we show that RASE can, in principle, produce perfect multimode time-delayed two mode squeezing when the active medium is placed inside a Q-switched cavity.

Williamson, Lewis A.; Longdell, Jevon J.

2014-07-01

30

Wavelength swept amplified spontaneous emission source.  

PubMed

We present a new, alternative approach to realize a wavelength swept light source with no fundamental limit to sweep speed. Amplified spontaneous emission (ASE) light alternately passes a cascade of optical gain elements and tunable optical bandpass filters. We show that for high sweep speeds, the control signal for the different filters has to be applied with a defined, precise phase delay on the order of nanoseconds, to compensate for the light propagation time between the filters and ensure optimum operation. At a center wavelength of 1300 nm sweep rates of 10 kHz, 100 kHz and 340 kHz over a sweep range of 100 nm full width and an average power of 50 mW are demonstrated. For application in optical coherence tomography (OCT), an axial resolution of 12 microm (air), a sensitivity of 120 dB (50 mW) and a dynamic range of 50 dB are achieved and OCT imaging is demonstrated. Performance parameters like coherence properties and relative intensity noise (RIN) are quantified, discussed and compared to the performance of Fourier Domain Mode Locked (FDML) lasers. Physical models for the observed difference in performance are provided. PMID:20372613

Eigenwillig, Christoph M; Biedermann, Benjamin R; Wieser, Wolfgang; Huber, Robert

2009-10-12

31

Amplified spontaneous emission in quaterthiophene single crystals  

Microsoft Academic Search

The authors demonstrate amplified spontaneous emission (ASE) from quaterthiophene single crystals and study its behavior at low temperature. The room temperature photoluminescence exhibits line narrowing (spectral width down to 10 nm) at 553 nm for excitation fluence larger than 1 mJ cm-2. At low temperature (10 K), ASE is observed from two vibronic transitions at 510 nm (0-1) and 553

Marco Polo; Andrea Camposeo; Silvia Tavazzi; Luisa Raimondo; Peter Spearman; Antonio Papagni; Roberto Cingolani; Dario Pisignano

2008-01-01

32

Master-Equation Approach to Spontaneous Emission  

Microsoft Academic Search

Spontaneous emission from a system of N identical two-level atoms is considered using a master equation recently derived by the author. The master equation describing the time evolution of the phase-space distribution function associated with the reduced density operator of the atomic system is obtained. This master equation, which is of the type of a Fokker-Planck equation, is used to

G. S. Agarwal

1970-01-01

33

Competition between coherent emission and broadband spontaneous emission in the quantum free electron laser  

SciTech Connect

We extend previous analyses of spontaneous emission in a quantum free electron laser (QFEL) and competition between spontaneous and coherent QFEL emission to include a broad distribution of photon frequencies and momenta appropriate for spontaneous undulator radiation. We show that although the predictions of monochromatic and broadband models predict different electron momentum distributions for the quantum regime due to spontaneous emission alone after many photon emissions, the inclusion of broadband spontaneous emission has a negligible effect on the competition between spontaneous and coherent emission in the QFEL. Numerical results from both models are well described by the same condition for the threshold/critical value of spontaneous emission rate.

Robb, G. R. M. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG, Scotland (United Kingdom); Bonifacio, R. [INFN-LNF, Via E. Fermi, 40-00044 Frascati, Rome (Italy) and Departamento de Fisica, Universidade Federal da Paraiba, Joao Pessoa (Brazil)

2013-03-15

34

Kooperative spontane Emission von zwei ungleichen Atomen  

NASA Astrophysics Data System (ADS)

Es werden die totale Intensität, die Winkelverteilung der abgestrahlten Energie und Photonenkorrelationen der kooperativen spontanen Strahlung von zwei Atomen mit verschiedenen Resonanzfrequenzen und spontanen Zerfallsraten berechnet. Im Gegensatz zu zwei identischen Atomen treten in der totalen Intensität Oszillationen auf und weicht die Winkelverteilung der insgesamt emittierten Photonen von der Ein-Atom-Richtcharakteristik ab. Der Einfluß der Dipol-Dipol-Nahfeldwechselwirkung auf die zeitliche Entwicklung des Atomsystems wird diskutiert.Translated AbstractCooperative Spontaneous Emission from Two Different AtomsThe total radiation rate, angular distribution of the emitted energy and photon correlations of the cooperative spontaneous radiation from two atoms with different resonance frequencies and spontaneous decay rates are calculated. Contrary to the case of two identical atoms oscillations appear in the total radiation rate and the spatial distribution of the total number of emitted photons differs from the single-atom radiation pattern. The effect of the dipole-dipole near-field interaction on the time evolution of the atomic system is discussed.

Richter, Th.

35

Amplified spontaneous emission in Cassegrainian amplifiers  

SciTech Connect

We consider all possible paths for amplified spontaneous emission (ASE) in multipass laser amplifiers using a Cassegrainian telescope geometry. In particular, we study ASE which is reflected back into the medium off the telescope mirrors themselves. These ASE components are unavoidable in this amplifier geometry. We show that there is a component of the ASE which makes approximately double the number of passes through the amplifier as the laser signal makes. We also show that these high order ASE components are also present in amplifiers which are almost Cassegrainian. They cannot be eliminated by changing the ratio of the scraper and hole radii or the separation of the mirrors. It is likely that these ASE components will be more significant in pulsed lasers than cw lasers.

Eimerl, D.

1987-05-01

36

Wave optics modelling of amplified spontaneous emission  

SciTech Connect

A laser works by amplified spontaneous emission (ASE) of inverted atomic ions confined in an amplifier of rod-like geometry, such that ASE radiation is directed out of both ends of the rod. The forward and backward ASE waves are coupled through the population-rate equations and cause the saturation of the lasing transition (gain saturation). Diffraction of the waves in the transverse direction is responsible for the radiation pattern (angular distribution) observed on a distant screen and for the degree of spatial coherence of the radiation. Refraction of the light also occurs due to spatial gradients in the electron density. In order to describe this situation a code has been developed which numerically solves paraxial Maxwell's equations in the time and two spatial dimensions. The code uses the Peaceman-Rachford Alternating-Direction-Implicit algorithm and is benchmarked against laboratory DYE-LASER experiments. 4 refs., 1 fig.

Ritchie, B.; Garrison, J.

1990-11-06

37

Spontaneous emission from a fractal vacuum  

NASA Astrophysics Data System (ADS)

Spontaneous emission of a quantum emitter coupled to a QED vacuum with a deterministic fractal structure of its spectrum is considered. We show that the decay probability does not follow a Wigner-Weisskopf exponential decrease but rather an overall power law behavior with a rich oscillatory structure, both depending on the local fractal properties of the vacuum spectrum. These results are obtained by giving first a general perturbative derivation for short times. Then we propose a simplified model which retains the main features of a fractal spectrum to establish analytic expressions valid for all time scales. Finally, we discuss the case of a Fibonacci cavity and its experimental relevance to observe these results.

Akkermans, Eric; Gurevich, Evgeni

2013-08-01

38

Restoring dark lines in spontaneous emission via Fano interference  

Microsoft Academic Search

We investigate the effects of spontaneous emission on two different laser-driven autoionization systems. We find that, under specific conditions, the relaxation decay processes can interfere destructively and lead to dark lines and spectral narrowing in the spontaneous emission spectra of these systems.

E. Paspalakis; P. L. Knight

1999-01-01

39

L-band automatic-gain-controlled erbium-doped fiber amplifier utilizing C-band backward-amplified spontaneous emission and electrical feedback monitor.  

PubMed

A new L-band automatic-gain-controlled (AGC) erbium-doped fiber amplifier (EDFA) for dense wavelength-division-multiplexing transmission systems is presented, in which a single 1480 nm laser with an internal thermoelectric cooler is used as a primary pump for stable amplification. All C-band amplified spontaneous emission (ASE) is recycled by the secondary pump to enhance the gain efficiency. A fraction of the output signal is used as an electrical feedback monitor for the AGC to improve the gain-clamped (GC) flatness. Experimental results prove that the AGC EDFA has a gain flatness of better than 0.46 dB/40 nm, i.e., below 1.5%, and a higher gain of approximately 36.5 dB compared to that of approximately 35.3 dB for the conventional GC EDFA at -30 dBm input signal power. The best gain flatness of +/-0.25 dB can be achieved over the dynamic range greater than 20 dB. The dynamic range of noise figure is between 6.7 and 7.1. The 3 dB down bandwidth is more than 40 nm. Overall dynamics measurements for the AGC EDFA feedback stabilization have been carried out. The recorded corresponding rise time of 1.565 ms indicates that the system does not exhibit any overshoot of gain or ASE variation due to the signal at the beginning of the pulse. PMID:19209194

Shen, Jyi-Lai; Lee, Yueh-Chien; Huang, Chia-Chih

2009-02-10

40

Loss of spatial coherence by a single spontaneous emission  

Microsoft Academic Search

We have demonstrated the loss of transverse spatial coherence of an atomic wave function after a single spontaneous emission. He* atoms were both diffracted and excited by a standing light wave with a variable period. After the interaction, the excited atoms decay by a single spontaneously emitted photon. By changing the period of the standing light wave, we have mapped

T. Pfau; S. Spälter; Ch. Kurtsiefer; C. R. Ekstrom; J. Mlynek

1994-01-01

41

Spontaneous Emission of Organic Molecules Embedded in a Photonic Crystal  

Microsoft Academic Search

We report on modification of the spontaneous emission of dye molecules embedded in a three- dimensional solid-state photonic crystal exhibiting a stop band in the visible range. Molecules embedded in artificial opal filled with a polymer show a dip in the fluorescence spectrum and nonexponential spontaneous decay kinetics containing both accelerated and inhibited components compared to the dye fluorescence in

E. P. Petrov; V. N. Bogomolov; I. I. Kalosha; S. V. Gaponenko

1998-01-01

42

Spontaneous emission of an atom in the presence of nanobodies  

SciTech Connect

The effect of nanobodies, i.e., the bodies whose size is small compared to the emission wavelength, on spontaneous emission of an atom located near them is considered. The results of calculations performed within the framework of quantum and classical electrodynamics are presented both in analytic and graphical forms and can be readily used for planning experiments and analysis of experimental data. It is shown that nanobodies can be used to control efficiently the rate of spontaneous transitions. Thus, an excited atom located near a nanocylinder or a nanospheroid pole, whose transition dipole moment is directed normally to the nanobody surface, can decay with the rate that is tens and hundreds times higher than the decay rate in a free space. In the case of some (negative) dielectric constants, the decay rate can increase by a factor of 10{sup 5}-10{sup 6} and more. On the other hand, the decay of an excited atom whose transition dipole moment is directed tangentially to the nanobody surface substantially slows down. The probability of nonradiative decay of the excited state is shown to increase substantially in the presence of na-nobodies possessing losses. (review)

Klimov, Vasilii V [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Ducloy, M [Laboratoire de Physique des Lasers, UMR CNRS 7538 University Paris-Nord, Institut Galilee (France); Letokhov, V S [Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow region (Russian Federation)

2001-07-31

43

2-.mu.m Fiber Amplified Spontaneous Emission (ASE) Source.  

National Technical Information Service (NTIS)

A 2-(mu)m fiber Amplified Spontaneous Emission (ASE) source provides a wide emission bandwidth and improved spectral stability/purity for a given output power. The fiber ASE source is formed from a heavy metal oxide multicomponent glass selected from germ...

J. Geng, J. Wu S. Jiang

2007-01-01

44

Spontaneous emission in the presence of a spherical plasmonic cloak  

E-print Network

We investigate the spontaneous emission of a two-level atom placed in the vicinities of a plasmonic cloak composed of a coated sphere. In the dipole approximation, we show that the spontaneous emission rate can be reduced to its vacuum value provided the atomic emission frequency lies within the plasmonic cloak frequency operation range. Considering the current status of plasmonic cloaking devices, this condition may be fulfilled for many atomic species so that we argue that atoms with a sufficiently strong transition can be used as quantum, local probes for the efficiency of plasmonic cloaks.

W. J. M. Kort-Kamp; F. S. S. Rosa; F. A. Pinheiro; C. Farina

2012-10-15

45

Reversible Modulation of Spontaneous Emission by Strain in Silicon Nanowires  

PubMed Central

We computationally study the effect of uniaxial strain in modulating the spontaneous emission of photons in silicon nanowires. Our main finding is that a one to two orders of magnitude change in spontaneous emission time occurs due to two distinct mechanisms: (A) Change in wave function symmetry, where within the direct bandgap regime, strain changes the symmetry of wave functions, which in turn leads to a large change of optical dipole matrix element. (B) Direct to indirect bandgap transition which makes the spontaneous photon emission to be of a slow second order process mediated by phonons. This feature uniquely occurs in silicon nanowires while in bulk silicon there is no change of optical properties under any reasonable amount of strain. These results promise new applications of silicon nanowires as optoelectronic devices including a mechanism for lasing. Our results are verifiable using existing experimental techniques of applying strain to nanowires. PMID:22708056

Shiri, Daryoush; Verma, Amit; Selvakumar, C. R.; Anantram, M. P.

2012-01-01

46

Collective spontaneous emission of two atoms near metal nanoparticle  

E-print Network

We present quantum-mechanical approach for collective spontaneous emission (superradiance) of emitters (as atoms) near metal nanoparticle, when frequencies of transitions of emitters coincide with frequency of localized plasmon resonance of the nanoparticle. Our approach is based on Schrodinger description and it uses wave functions of states of systems. Interactions between emitters and between the nanoparticle and emitters are taken into account. We consider an example of two emitters and show that radiation is occurred through symmetric states of emitters as it is in Dicke model of superradiance. The nanoparticle accelerates collective spontaneous emission similar how it accelerates spontaneous emission of single emitter. Radiation from two emitters near the nanoparticle is faster than the radiation from two separated and non-interacted "nanoparticle+single emitter" systems. Efficiency of superradiance, i.e. the ratio of emitted photons to total number initial excitations in the system, is smaller than 1 d...

Protsenko, Igor

2014-01-01

47

Large spontaneous emission rate enhancement in grating coupled hyperbolic metamaterials.  

PubMed

Hyperbolic metamaterial (HMM), a sub-wavelength periodic artificial structure with hyperbolic dispersion, can enhance the spontaneous emission of quantum emitters. Here, we demonstrate the large spontaneous emission rate enhancement of an organic dye placed in a grating coupled hyperbolic metamaterial (GCHMM). A two-dimensional (2D) silver diffraction grating coupled with an Ag/Al2O3 HMM shows 18-fold spontaneous emission decay rate enhancement of dye molecules with respect to the same HMM without grating. The experimental results are compared with analytical models and numerical simulations, which confirm that the observed enhancement of GCHMM is due to the outcoupling of non-radiative plasmonic modes as well as strong plasmon-exciton coupling in HMM via diffracting grating. PMID:25209102

Sreekanth, Kandammathe Valiyaveedu; Krishna, Koduru Hari; De Luca, Antonio; Strangi, Giuseppe

2014-01-01

48

Large spontaneous emission rate enhancement in grating coupled hyperbolic metamaterials  

NASA Astrophysics Data System (ADS)

Hyperbolic metamaterial (HMM), a sub-wavelength periodic artificial structure with hyperbolic dispersion, can enhance the spontaneous emission of quantum emitters. Here, we demonstrate the large spontaneous emission rate enhancement of an organic dye placed in a grating coupled hyperbolic metamaterial (GCHMM). A two-dimensional (2D) silver diffraction grating coupled with an Ag/Al2O3 HMM shows 18-fold spontaneous emission decay rate enhancement of dye molecules with respect to the same HMM without grating. The experimental results are compared with analytical models and numerical simulations, which confirm that the observed enhancement of GCHMM is due to the outcoupling of non-radiative plasmonic modes as well as strong plasmon-exciton coupling in HMM via diffracting grating.

Sreekanth, Kandammathe Valiyaveedu; Krishna, Koduru Hari; de Luca, Antonio; Strangi, Giuseppe

2014-09-01

49

Amplified spontaneous emission in solar-pumped iodine laser  

NASA Technical Reports Server (NTRS)

The amplified spontaneous emission (ASE) from a long pulse, solar-simulating radiation pumped iodine laser amplifier is studied. The ASE threshold pump intensity is almost proportional to the inverse of the laser gain length when the gas pressure is constant in the laser tube.

Cho, Yong S.; Hwang, In H.; Han, Kwang S.; Lee, Ja H.

1992-01-01

50

Spontaneous emission in a silicon charge qubit  

E-print Network

The interaction between a qubit and its environment provides a channel for energy relaxation which has an energy-dependent timescale governed by the specific coupling mechanism. We measure the rate of inelastic decay in a Si MOS double quantum dot (DQD) charge qubit through sensing the charge state's response to non-adiabatic driving of its excited state population. The charge distribution is sensed remotely in the weak measurement regime. We extract emission rates down to kHz frequencies by measuring the variation of the non-equilibrium charge occupancy as a function of amplitude and dwell times between non-adiabatic pulses. Our measurement of the energy-dependent relaxation rate provides a fingerprint of the relaxation mechanism, indicating that relaxation rates for this Si MOS DQD are consistent with coupling to deformation acoustic phonons.

Khoi T. Nguyen; N. Tobias Jacobson; Michael P. Lilly; Nathaniel C. Bishop; Erik Nielsen; Joel R. Wendt; J. Dominguez; T. Pluym; Malcolm S. Carroll

2014-03-14

51

hal-00136128,version1-12Mar2007 Spontaneous emission of graviton by a quantum  

E-print Network

hal-00136128,version1-12Mar2007 Spontaneous emission of graviton by a quantum bouncer G Pignol, K, Grenoble, France Abstract. Spontaneous emission of graviton rates for the quantum bouncer states of this problem #12;Spontaneous emission of graviton by a quantum bouncer 2 are: z0 = 2 2m2g 1/3 = 5.87 µm (2) E0

Paris-Sud XI, Université de

52

Spontaneous emission and thermalization of cold bosons in optical lattices  

NASA Astrophysics Data System (ADS)

We study the thermalization of excitations generated by spontaneous emission events for cold bosons in an optical lattice. Computing the dynamics described by the many-body master equation, we characterize equilibration time scales in different parameter regimes. For simple observables, we find regimes in which the system relaxes rapidly to values in agreement with a thermal distribution, and others where thermalization does not occur on typical experimental time scales. Because spontaneous emissions lead effectively to a local quantum quench, this behavior is strongly dependent on the low-energy spectrum of the Hamiltonian, and undergoes a qualitative change at the Mott insulator-superfluid transition point. These results have important implications for the understanding of thermalization after localized quenches in isolated quantum gases, as well as the characterization of heating in experiments.

Schachenmayer, J.; Pollet, L.; Troyer, M.; Daley, A. J.

2014-01-01

53

Are Einstein's transition probabilities for spontaneous emission constant in plasmas?  

NASA Technical Reports Server (NTRS)

An investigation is conducted with a ruby laser to experimentally confirm the quenching of spontaneous emission coefficients and propose a mechanism for the phenomenon. Results of previous experiments are examined to determine the consistency and validity of interpretations of the spontaneous emissions. For the C IV 3s-3p and 2s-3p transitions, the line-intensity ratios are found to be dependent on the separation of the laser from the target. Density gradients and Stark broadening are proposed to interpret the results in a way that does not invalidate the Einstein A values. The interpretation is extended to C III and N V, both of which demonstrate similar changes in A values in previous experiments. The apparent quenching of Ar II by photon collisions is explained by Rabi oscillations and power broadening in the argon-ion laser cavity. It is concluded that the changes in A values cannot result from dense plasma effects.

Griem, H. R.; Huang, Y. W.; Wang, J.-S.; Moreno, J. C.

1991-01-01

54

Modifying free-space spontaneous emission near a plasmonic nanostructure  

SciTech Connect

We study theoretically the effects of the presence of a plasmonic nanostructure on free-space spontaneous emission in a four-level quantum system, where one V-type transition is influenced by the interaction with surface plasmons and the other V-type transition occurs in free space. The plasmonic nanostructure that we consider is a two-dimensional array of metal-coated dielectric nanospheres. We show that the spectrum of spontaneous emission in the free-space modes is strongly influenced by the presence of the plasmonic nanostructure, and we explore the dependence of the spectrum on different initial conditions of the quantum system and on the distance from the nanostructure.

Evangelou, Sofia; Yannopapas, Vassilios; Paspalakis, Emmanuel [Materials Science Department, School of Natural Sciences, University of Patras, GR-265 04 Patras (Greece)

2011-02-15

55

Spectrum in spontaneous emission: Beyond the Weisskopf-Wigner approximation  

SciTech Connect

The theory of spontaneous emission presented by Weisskopf and Wigner [V. Weisskopf and E. Wigner, Z. Phys. 63, 54 (1930)] provides an excellent approximation of the actual decay that atoms undergo on optically allowed transitions. However, the theory cannot be rigorously correct since it leads to a Lorentzian spectrum that extends to negative frequencies. Within the rotating-wave approximation, we derive a closed-form expression for the spectrum that is valid for all frequencies.

Berman, P. R.; Ford, G. W. [Michigan Center for Theoretical Physics and Physics Department, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040 (United States)

2010-08-15

56

2-.mu.m fiber amplified spontaneous emission (ASE) source  

NASA Technical Reports Server (NTRS)

A 2-.mu.m fiber Amplified Spontaneous Emission (ASE) source provides a wide emission bandwidth and improved spectral stability/purity for a given output power. The fiber ASE source is formed from a heavy metal oxide multicomponent glass selected from germanate, tellurite and bismuth oxides and doped with high concentrations, 0.5-15 wt. %, thulium oxides (Tm.sub.2O.sub.3) or 0.1-5 wt% holmium oxides (Ho.sub.2O.sub.3) or mixtures thereof. The high concentration of thulium dopants provide highly efficient pump absorption and high quantum efficiency. Co-doping of Tm and Ho can broaden the ASE spectrum.

Jiang, Shibin (Inventor); Wu, Jianfeng (Inventor); Geng, Jihong (Inventor)

2007-01-01

57

Phonon-modified spontaneous emission from single quantum dots in a structured photonic medium  

E-print Network

We describe how a structured photonic medium controls the spontaneous emission from an excited quantum dot in the presence of electron-phonon coupling. We analyze this problem using a polaron transformed master equation and we consider specific examples of a photonic crystal defect cavity and a coupled cavity waveguide. We find that when the relaxation dynamics of photon and phonon baths are comparable, phonons influence spontaneous emission in a non-trivial way. We demonstrate why and how the broadband frequency dependence of the local photon density of states determines the photon emission rate, manifesting in a complete breakdown of Fermi's golden rule. For a single cavity resonance, we present a simple fix to Purcell's formula to include electron-phonon coupling.

Roy-Choudhury, Kaushik

2014-01-01

58

Quantum theory of spontaneous and stimulated emission of surface plasmons  

SciTech Connect

We introduce a quantization scheme that can be applied to surface waves propagating along a plane interface. An important result is the derivation of the energy of the surface wave for dispersive nonlossy media without invoking any specific model for the dielectric constant. Working in Coulomb's gauge, we use a modal representation of the fields. Each mode can be associated with a quantum harmonic oscillator. We have applied the formalism to derive quantum mechanically the spontaneous emission rate of surface plasmon by a two-level system. The result is in very good agreement with Green's tensor approach in the nonlossy case. Green's approach allows also to account for losses, so that the limitations of a quantum approach of surface plasmons are clearly defined. Finally, the issue of stimulated versus spontaneous emission has been addressed. Because of the increasing density of states near the asymptote of the dispersion relation, it is quantitatively shown that the stimulated emission probability is too small to obtain gain in this frequency region.

Archambault, Alexandre; Marquier, Francois; Greffet, Jean-Jacques; Arnold, Christophe [Laboratoire Charles Fabry, Institut d Optique, CNRS-Univ Paris-Sud, Campus Polytechnique, RD128, 91127 Palaiseau Cedex (France); Laboratoire de Photonique et de Nanostructures, CNRS, Route de Nozay, 91460 Marcoussis (France)

2010-07-15

59

Demonstration of Weak Measurement Based on Atomic Spontaneous Emission  

NASA Astrophysics Data System (ADS)

We demonstrate a new type of weak measurement based on the dynamics of spontaneous emission. The pointer in our scheme is given by the Lorentzian distribution characterizing atomic exponential decay via emission of a single photon. We thus introduce weak measurement, so far demonstrated nearly exclusively with laser beams and Gaussian statistics, into the quantum regime of single emitters and single quanta, enabling the exploitation of a wide class of sources that are abundant in nature. We describe a complete analogy between our scheme and weak measurement with conventional Gaussian pointers. Instead of a shift in the mean of a Gaussian distribution, an imaginary weak value is exhibited in our scheme by a significantly slower-than-natural exponential distribution of emitted photons at the postselected polarization, leading to a large shift in their mean arrival time. The dynamics of spontaneous emission offer a broader view of the measurement process than is usually considered within the weak measurement formalism. Our scheme opens the path for the use of atoms and atomlike systems as sensitive probes in weak measurements, one example being optical magnetometry.

Shomroni, Itay; Bechler, Orel; Rosenblum, Serge; Dayan, Barak

2013-07-01

60

Investigation of ultrashort traveling-wave amplified spontaneous emission  

SciTech Connect

Ultrashort traveling-wave amplified spontaneous emission (ASE) is generated by a transverse synchronous pumping scheme with a gradient distribution of pumping energy. 50 ps light pulses are generated by nitrogen laser pumping and 8 to 15 ps pulses are generated by pumping with a frequency-doubled mode-locked Nd:YAG laser. The pulse shape and spectrum of the traveling-wave ASE as well as the nontraveling-wave ASE are measured by means of streak camera and optical multichannel analyzer, respectively. The computer simulation on the temporal behavior of the traveling-wave ASE is presented and the calculation result is in good agreement with the experimental results.

Li Wenchong; Ning Changlong; Huang Zuozhu; Chen Jian; Wang Wanlun

1987-07-01

61

Spontaneous Radiation Emission from Short, High Field Strength Insertion Devices  

SciTech Connect

Since the earliest papers on undulaters were published, it has been known how to calculate the spontaneous emission spectrum from ''short'' undulaters when the magnetic field strength parameter is small compared to unity, or in ''single'' frequency sinusoidal undulaters where the magnetic field strength parameter is comparable to or larger than unity, but where the magnetic field amplitude is constant throughout the undulater. Fewer general results have been obtained in the case where the insertion device is both short, i.e., the magnetic field strength parameter changes appreciably throughout the insertion device, and the magnetic field strength is high enough that ponderomotive effects, radiation retardation, and harmonic generation are important physical phenomena. In this paper a general method is presented for calculating the radiation spectrum for short, high-field insertion devices. It is used to calculate the emission from some insertion device designs of recent interest.

Geoffrey Krafft

2005-09-15

62

TRASER - Total Reflection Amplification of Spontaneous Emission of Radiation  

PubMed Central

Background and Objective Light and lasers in medical therapy have made dramatic strides since their invention five decades ago. However, the manufacture of lasers can be complex and expensive which often makes treatments limited and costly. Further, no single laser will provide the correct parameters to treat all things. Hence, laser specialists often need multiple devices to practice their specialty. A new concept is described herein that has the potential to replace many lasers and light sources with a single ‘tunable’ device. Study Design/Material and Methods This device amplifies spontaneous emission of radiation by capturing and retaining photons through total internal reflection, hence the acronym Total Reflection Amplification of Spontaneous Emission of Radiation, or TRASER. Results Specific peaks of light can be produced in a reproducible manner with high peak powers of variable pulse durations, a large spot size, and high repetition rate. Conclusion Considering the characteristics and parameters of Traser technology, it is possible that this one device would likely be able to replace the pulsed dye laser and many other light based systems. PMID:22558261

Zachary, Christopher B.; Gustavsson, Morgan

2012-01-01

63

The amplified spontaneous emission in EDF with small pulse pump  

NASA Astrophysics Data System (ADS)

The amplified Spontaneous Emission (ASE) is the important noise source for EDFA, affecting the EDFA based fiber laser seriously. The theory and practice have shown that the ASE is closely related with pump methods, so the study on the ASE of EDF under the condition of the pulse pumping has important academic significations. What's more, the mode-locked laser based on EDFA fiber ring could be pumping by the pulse to realized mode-lock, and the ASE will impact its characteristics. In this paper, the effects of pump pulse with different width and amplitude on the ASE were investigated by the theoretical and experiment methods. Beginning with the carrier density rate equation, we can get each level of the distribution of the number of particles carriers along with the change of time based on the relationship between the average number of photons of the spontaneous radiation and the number of particles carriers distribution. An approximate analytic solution of output ASE noise average is derived when pump signal is small.Building an experimental system, the results show that the output amplitude of ASE is proportional to the input width of pump pulse when the pump pulse is small. It's also shows that the output amplitude of ASE is proportional to the input amplitude of pump pulse. The new phenomena can be used for the all-optical measurement of a pulse width.

Wang, Fu; Wu, Chongqing; Liu, Lanlan; Wang, Zhi; Sun, Zhenchao; Mao, Yaya

2012-11-01

64

Spontaneous Muon Emission during Fission, a New Nuclear Radioactivity  

E-print Network

In this paper the essential theoretical predictions for the nuclear muonic radioactivity are presented by using a special fission-like model similar with that used in description of the pionic emission during fission. Hence, a fission-like model for the muonic radioactivity takes into account the essential degree of freedom of the system: muon-fissility, muon-fission barrier height, etc. Using this model it was shown that most of the SHE-nuclei lie in the region where the muonic fissility parameters attain their limiting value X=1. Hence, the SHE-region is characterized by the absence of a classical barrier toward spontaneous muon and pion emissions. Numerical estimations on the yields for the natural muonic radioactivities of the transuranium elements as well numerical values for barrier heights are given only for even-even parent nuclei. Some experimental results from LCP-identification emission spectrum are reviewed. Also, the experimental results obtained by Khryachkov et al, using new spectrometer for investigation of ternary nuclear fission, are presented. The OPERA-experiment proposed to perform search for muonic radioactivity from lead nuclei, in the low background conditions offered by the Gran Sasso underground Laboratory (LNGS), is discussed.

D. B. Ion; M. L. D. Ion; Reveica Ion-Mihai

2011-01-24

65

Spontaneous Muon Emission during Fission, a New Nuclear Radioactivity  

E-print Network

In this paper the essential theoretical predictions for the nuclear muonic radioactivity are presented by using a special fission-like model similar with that used in description of the pionic emission during fission. Hence, a fission-like model for the muonic radioactivity takes into account the essential degree of freedom of the system: muon-fissility, muon-fission barrier height, etc. Using this model it was shown that most of the SHE-nuclei lie in the region where the muonic fissility parameters attain their limiting value X=1. Hence, the SHE-region is characterized by the absence of a classical barrier toward spontaneous muon and pion emissions. Numerical estimations on the yields for the natural muonic radioactivities of the transuranium elements as well numerical values for barrier heights are given only for even-even parent nuclei. Some experimental results from LCP-identification emission spectrum are reviewed. Also, the experimental results obtained by Khryachkov et al, using new spectrometer for in...

Ion, D B; Ion-Mihai, Reveica

2011-01-01

66

Optical steganography based on amplified spontaneous emission noise.  

PubMed

We propose and experimentally demonstrate an optical steganography method in which a data signal is transmitted using amplified spontaneous emission (ASE) noise as a carrier. The ASE serving as a carrier for the private signal has an identical frequency spectrum to the existing noise generated by the Erbium doped fiber amplifiers (EDFAs) in the transmission system. The system also carries a conventional data channel that is not private. The so-called "stealth" or private channel is well-hidden within the noise of the system. Phase modulation is used for both the stealth channel and the public channel. Using homodyne detection, the short coherence length of the ASE ensures that the stealth signal can only be recovered if the receiver closely matches the delay-length difference, which is deliberately changed in a dynamic fashion that is only known to the transmitter and its intended receiver. PMID:23389187

Wu, Ben; Wang, Zhenxing; Tian, Yue; Fok, Mable P; Shastri, Bhavin J; Kanoff, Daniel R; Prucnal, Paul R

2013-01-28

67

WDM optical steganography based on amplified spontaneous emission noise.  

PubMed

We propose and experimentally demonstrate a wavelength-division multiplexed (WDM) optical stealth transmission system carried by amplified spontaneous emission (ASE) noise. The stealth signal is hidden in both time and frequency domains by using ASE noise as the signal carrier. Each WDM channel uses part of the ASE spectrum, which provides more flexibility to apply stealth transmission in a public network and adds another layer of security to the stealth channel. Multi-channel transmission also increases the overall channel capacity, which is the major limitation of the single stealth channel transmission based on ASE noise. The relations between spectral bandwidth and coherence length of ASE carrier have been theoretically analyzed and experimentally investigated. PMID:25361121

Wu, Ben; Tait, Alexander N; Chang, Matthew P; Prucnal, Paul R

2014-10-15

68

Amplified spontaneous emission (ASE) in laser oscillators and amplifiers  

SciTech Connect

Dye-laser oscillators and amplifiers are studied theoretically with inclusion of amplified spontaneous emission (ASE). Assuming pencil-like geometry in both cases, laser signal intensity and ASE intensity are described with appropriate photon transport equations. In particular, there exist different boundary conditions for both fluxes in the laser cavity case due to the different feedback behavior of an optical resonator for laser modes and ASE modes. The interaction of laser output and ASE intensity is discussed in detail, including laser output optimization with and without ASE effects. For single and double pass amplifiers, closed-form solutions for gain saturation due to input signal and ASE flux are also given. More complicated gain functions, such as inclusion of reabsorption in dye lasers, are also treated in some detail.

Haag, G.; Marowsky, G.; Munz, M.

1983-06-01

69

Atomic dipole traps with Amplified Spontaneous Emission: A proposal  

NASA Astrophysics Data System (ADS)

We propose what we believe to be a novel type of optical source for ultra-cold atomic Far Off-Resonance optical-dipole Traps. The source is based on an Erbium Amplified Spontaneous Emission (ASE) source that seeds a high power Erbium Doped Fiber Amplifier. The main interest of this source is its very short coherence length, thus allowing an incoherent superposition of several trapping beams without any optical interference. The behavior of the superimposed beams is then a scalar sum greatly simplifying complex configurations. As an illustration, we report an estimation of the intensity noise of this source and an estimation of the additional atomic heating rate for an evaporative cooling experiment application. They are both found to be suitable for cold atoms experiments.

Clément, Jean-François; Zehnlé, Véronique; Garreau, Jean Claude; Szriftgiser, Pascal

2010-11-01

70

Frequency shift of individual spontaneous otoacoustic emissions in preterm infants.  

PubMed

In adults, spontaneous otoacoustic emissions (SOAE) have shown a considerable frequency stability. In preterm infants, however, the SOAE proved to show an apparent and consistent upward shift of frequency at increasing postconceptional age (PCA). In 25 ears of 14 preterm infants (PCA, 29.1-41.3 wk) a total of 66 SOAE frequencies were monitored, ranging from 1611 to 5774 Hz. All but one of the SOAE frequencies shifted toward higher frequency. The SOAE frequency shift rate in Hertz per week was proportionally constant relative to the SOAE frequency. The mean shift rate was 0.74 +/- 0.39%/wk. At increasing PCA, the SOAE frequency shift rate tended to slow down. A linear fit through the data predicted the SOAE frequency to stop at about 45-50-wk PCA. The frequency dependence and time course of the SOAE frequency shift strongly suggest cochlear maturation during the last period of gestation. PMID:9380439

Brienesse, P; Anteunis, L J; Maertzdorf, W J; Blanco, C E; Manni, J J

1997-10-01

71

Spontaneous emission noise in long-range surface plasmon polariton waveguide based optical gyroscope.  

PubMed

Spontaneous emission noise is an important limit to the performance of active plasmonic devices. Here, we investigate the spontaneous emission noise in the long-range surface plasmon-polariton waveguide based optical gyroscope. A theoretical model of the sensitivity is established to study the incoherent multi-beam interference of spontaneous emission in the gyroscope. Numerical results show that spontaneous emission produces a drift in the transmittance spectra and lowers the signal-to-noise-ratio of the gyroscope. It also strengthens the shot noise to be the main limit to the sensitivity of the gyroscope for high propagation loss. To reduce the negative effects of the spontaneous emission noise on the gyroscope, an external feedback loop is suggested to estimate the drift in the transmittance spectra and therefor enhance the sensitivity. Our work lays a foundation for the improvement of long-range surface plasmon-polariton gyroscope and paves the way to its practical application. PMID:25234712

Wang, Yang-Yang; Zhang, Tong

2014-01-01

72

Spontaneous emission noise in long-range surface plasmon polariton waveguide based optical gyroscope  

PubMed Central

Spontaneous emission noise is an important limit to the performance of active plasmonic devices. Here, we investigate the spontaneous emission noise in the long-range surface plasmon-polariton waveguide based optical gyroscope. A theoretical model of the sensitivity is established to study the incoherent multi-beam interference of spontaneous emission in the gyroscope. Numerical results show that spontaneous emission produces a drift in the transmittance spectra and lowers the signal-to-noise-ratio of the gyroscope. It also strengthens the shot noise to be the main limit to the sensitivity of the gyroscope for high propagation loss. To reduce the negative effects of the spontaneous emission noise on the gyroscope, an external feedback loop is suggested to estimate the drift in the transmittance spectra and therefor enhance the sensitivity. Our work lays a foundation for the improvement of long-range surface plasmon-polariton gyroscope and paves the way to its practical application. PMID:25234712

Wang, Yang-Yang; Zhang, Tong

2014-01-01

73

Spontaneous emission noise in long-range surface plasmon polariton waveguide based optical gyroscope  

NASA Astrophysics Data System (ADS)

Spontaneous emission noise is an important limit to the performance of active plasmonic devices. Here, we investigate the spontaneous emission noise in the long-range surface plasmon-polariton waveguide based optical gyroscope. A theoretical model of the sensitivity is established to study the incoherent multi-beam interference of spontaneous emission in the gyroscope. Numerical results show that spontaneous emission produces a drift in the transmittance spectra and lowers the signal-to-noise-ratio of the gyroscope. It also strengthens the shot noise to be the main limit to the sensitivity of the gyroscope for high propagation loss. To reduce the negative effects of the spontaneous emission noise on the gyroscope, an external feedback loop is suggested to estimate the drift in the transmittance spectra and therefor enhance the sensitivity. Our work lays a foundation for the improvement of long-range surface plasmon-polariton gyroscope and paves the way to its practical application.

Wang, Yang-Yang; Zhang, Tong

2014-09-01

74

Room temperature spontaneous emission enhancement from quantum dots in photonic crystal slab cavities in the telecommunications C-band  

E-print Network

We report on the control of the spontaneous emission dynamics from InAsP self-assembled quantum dots emitting in the telecommunications C-band and weakly coupled to the mode of a double heterostructure cavity etched on a suspended InP membrane at room temperature. The quality factor of the cavity mode is 44x10^3 with an ultra-low modal volume of the order of 1.2 lambda/n)^3, inducing an enhancement of the spontaneous emission rate of up a factor of 2.8 at 300 K.

Richard Hostein; Rémy Braive; Matthieu Larqué; Ko-Hsin Lee; Anne Talneau; Luc Le Gratiet; Isabelle Robert-Philip; Isabelle Sagnes; Alexios Beveratos

2009-03-25

75

Excitation dependent two-component spontaneous emission and ultrafast amplified spontaneous emission in dislocation-free InGaN nanowires  

SciTech Connect

Amplified spontaneous emission (ASE) at 456 nm from In{sub 0.2}Ga{sub 0.8}N nanowires grown on (001) silicon by catalyst-free molecular beam epitaxy was observed at room temperature under femtosecond excitation. The photoluminescence spectra below ASE threshold consist of two spontaneous emission bands centered at {approx}555 nm and {approx}480 nm, respectively, revealing the co-existence of deeply and shallowly localized exciton states in the nanowires. The ASE peak emerges from the 480 nm spontaneous emission band when the excitation density exceeds {approx}120 {mu}J/cm{sup 2}, indicating that optical gain arises from the radiative recombination of shallowly localized excitons in the nanowires. Time-resolved photoluminescence measurements revealed that the ASE process completes within 1.5 ps, suggesting a remarkably high stimulated emission recombination rate in one-dimensional InGaN nanowires.

You, Guanjun; Zhang, Chunfeng; Xu, Jian [Department of Engineering Science and Mechanics, The Penn State University, University Park, Pennsylvania 16802 (United States)] [Department of Engineering Science and Mechanics, The Penn State University, University Park, Pennsylvania 16802 (United States); Guo, Wei; Bhattacharya, Pallab [Center for Nanoscale Photonics and Spintronics, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Center for Nanoscale Photonics and Spintronics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Henderson, Ron [Department of Physics and Astronomy, Middle Tennessee State University, Murfreesboro, Tennessee 37132 (United States)] [Department of Physics and Astronomy, Middle Tennessee State University, Murfreesboro, Tennessee 37132 (United States)

2013-03-04

76

Prompt Neutron Emission in 252CF Spontaneous Fission  

NASA Astrophysics Data System (ADS)

The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics. The goal was to compare the results from digital data acquisition and digital signal processing analysis with results of the pioneering work of Budtz-Jørgensen and Knitter. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 107 fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The results are in very good agreement with literature. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

Hambsch, F.-J.; Oberstedt, S.; Zeynalov, Sh.

2011-10-01

77

Vacuum field energy and spontaneous emission in anomalously dispersive cavities  

SciTech Connect

Anomalously dispersive cavities, particularly white-light cavities, may have larger bandwidth to finesse ratios than their normally dispersive counterparts. Partly for this reason, they have been proposed for use in laser interferometer gravitational-wave observatory (LIGO)-like gravity-wave detectors and in ring-laser gyroscopes. In this paper we analyze the quantum noise associated with anomalously dispersive cavity modes. The vacuum field energy associated with a particular cavity mode is proportional to the cavity-averaged group velocity of that mode. For anomalously dispersive cavities with group index values between 1 and 0, this means that the total vacuum field energy associated with a particular cavity mode must exceed ({h_bar}/2{pi}){omega}/2. For white-light cavities in particular, the group index approaches zero and the vacuum field energy of a particular spatial mode may be significantly enhanced. We predict enhanced spontaneous emission rates into anomalously dispersive cavity modes and broadened laser linewidths when the linewidth of intracavity emitters is broader than the cavity linewidth.

Bradshaw, Douglas H.; Di Rosa, Michael D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2011-05-15

78

Automotive Emission Control.  

ERIC Educational Resources Information Center

This guide designed to assist teachers in improving instruction in the area of automotive emission control curriculum includes four areas. Each area consists of one or more units of instruction, with each instructional unit including some or all of the following basic components: Performance objectives, suggested activities for teacher and…

Lee, Billy D.; Ragazzi, Ronald

79

Spectral modulation of higher harmonic spontaneous emission from an optical klystron.  

PubMed

Higher harmonics of spontaneous emission from an optical klystron have been observed. The modulation factor of the spontaneous emission spectrum for the higher harmonics can be described by considering the observation system. When the dispersive gap of the optical klystron was fixed, the microstructure interval of the spontaneous emission spectrum at a certain resonant wavelength became narrower as the order of the higher harmonic became larger. Some unique characteristics of the higher harmonics have been clarified, and these studies are likely to contribute to the development of free-electron lasers using higher harmonics of an optical klystron in the shorter-wavelengths region. PMID:24971958

Sei, Norihiro; Ogawa, Hiroshi; Yamada, Kawakatsu; Koike, Masaki; Ohgaki, Hideaki

2014-07-01

80

Quantitative analysis of directional spontaneous emission spectra from light sources in photonic crystals  

E-print Network

Quantitative analysis of directional spontaneous emission spectra from light sources in photonic disorder. Using a model comprising diffuse light transport and photonic band structure, we quantitatively of spontaneously emitted light in real photonic crystals, which is essential in the interpretation of quantum

Vos, Willem L.

81

Calculations of spontaneous emission rates of a single-impurity molecule in uniaxial host crystals  

NASA Astrophysics Data System (ADS)

In a uniaxial host crystal the spontaneous emission rate of the dipole transition of the zero-phonon line of a single-impurity molecule depends on the angle between the transition dipole moment and the optical axis of a crystal and as well as on the ordinary and extraordinary refractive indices. The relative spontaneous emission rate (the spontaneous emission rate divided by the spontaneous emission rate in the case when the transition dipole moment is parallel to the optical axis) is determined through a simple formula by one coefficient. Here this coefficient is calculated as a function of the extraordinary refractive index for 40 values of the ordinary refractive index on the interval from 1.25 to 3.20. For comparison, the effects caused by the nearness to the plane interface between cinnabar crystal (HgS) and air, as an example, are calculated.

Rebane, Inna; Koch, Rein

2007-06-01

82

Organic light emitting materials : amplified spontaneous emission and hybrid inorganic-organic white light emitters.  

E-print Network

??Amplified spontaneous emission (ASE) from F8BT and MEH-PPV conjugated polymers with 1D distributed feedback (DFB) resonators was investigated. The conjugated polymers were spin-coated onto substrates… (more)

Yue, Zhounan

2011-01-01

83

The influence of density of modes on dark lines in spontaneous emission  

Microsoft Academic Search

We study two distinct multi-level atomic models in which one transition is coupled to a Markovian reservoir, while another linked transition is coupled to a non-Markovian reservoir. We show that by choosing appropriately the density of modes of the non-Markovian reservoir the spontaneous emission to the Markovian reservoir is greatly altered. The existence of ‘dark lines’ in the spontaneous emission

E. Paspalakis; D. G. Angelakis; P. L. Knight

1999-01-01

84

The influence of density of modes on dark lines in spontaneous emission  

Microsoft Academic Search

We study two distinct multi-level atomic models in which one transition is coupled to a Markovian reservoir, while another linked transition is coupled to a non-Markovian reservoir. We show that by choosing appropriately the density of modes of the non-Markovian reservoir the spontaneous emission to the Markovian reservoir is greatly altered. The existence of `dark lines' in the spontaneous emission

E. Paspalakis; D. G. Angelakis; P. L. Knight

1999-01-01

85

Theory of optical-environment-dependent spontaneous-emission rates for emitters in thin layers  

Microsoft Academic Search

The spontaneous-emission rates of emitters embedded in a thin layer 0 of a loss-free dielectric depend on their optical environment, i.e., on the optical properties of the two media 1 and 2 adjoining layer 0. For electric- and magnetic-dipole transitions the spontaneous-emission rates, normalized with respect to those in an infinite medium 0, are expressed in terms of the Fresnel

W. Lukosz

1980-01-01

86

Spontaneous emission in GaN/InGaN photonic crystal nanopillars.  

PubMed

We investigate the physics of spontaneous emission in a photonic crystal (PhC) made of GaN rods with embedded InGaN quantum wells, formed on a thick GaN layer. Although the PhC lies on a higher-index medium, we evidence the existence of unexpected quasi-guided Bloch modes which are strongly localized in the PhC region and possess a long lifetime. These modes determine the behavior of spontaneous emission such as the emission diagram and Purcell effect, as would happen in the usual case of emission in a PhC membrane. PMID:19551097

David, Aurelien; Benisty, Henri; Weisbuch, Claude

2007-12-24

87

A semi-analytical approach for evaluating effects of amplified spontaneous emission on characteristics of Q-switched lasers  

SciTech Connect

Possible effects of amplified spontaneous emission on output pulse characteristics of a Q-switched laser are discussed within the framework of a semi-analytical approach. It is shown that output energy decreases almost exponentially with average path length of the spontaneously emitted photons which in turn depends on geometrical specification and active medium properties as well as on optical finishing of the surfaces (for solid-state lasers). Optimal coupling dependence on the average path length is also investigated and shown to increase with average path length increment. (control of laser radiation parameters)

Razzaghi, D; Hajiesmaeilbaigi, F; Ruzbehani, M [Laser and Optics Research School, P.O. Box 11155-3486, Tehran (Iran, Islamic Republic of)

2012-08-31

88

REVIEW: Spontaneous emission of an atom in the presence of nanobodies  

NASA Astrophysics Data System (ADS)

The effect of nanobodies, i.e., the bodies whose size is small compared to the emission wavelength, on spontaneous emission of an atom located near them is considered. The results of calculations performed within the framework of quantum and classical electrodynamics are presented both in analytic and graphical forms and can be readily used for planning experiments and analysis of experimental data. It is shown that nanobodies can be used to control efficiently the rate of spontaneous transitions. Thus, an excited atom located near a nanocylinder or a nanospheroid pole, whose transition dipole moment is directed normally to the nanobody surface, can decay with the rate that is tens and hundreds times higher than the decay rate in a free space. In the case of some (negative) dielectric constants, the decay rate can increase by a factor of 105—106 and more. On the other hand, the decay of an excited atom whose transition dipole moment is directed tangentially to the nanobody surface substantially slows down. The probability of nonradiative decay of the excited state is shown to increase substantially in the presence of na-nobodies possessing losses.

Klimov, Vasilii V.; Ducloy, M.; Letokhov, V. S.

2001-07-01

89

Controllable spontaneous decay at material wedges  

SciTech Connect

We show that the de-excitation process of a dipole emitter can be altered controllably when it is embedded in a dielectric wedge of an arbitrary angle 0<{phi}{sub 0}{<=}2{pi}. We focus here on the case of a dielectric wedge bounded by a perfect conductor and show that the de-excitation process for different wedges, distinguished by {phi}{sub 0}, displays a wide range of features. Besides the dependence on the emitter location at the narrow end, the de-excitation process exhibits a strong dipole orientational dependence, suggesting that the system might serve as a qubit in a controllable scalable hardware architecture for the purpose of quantum information processing.

Skipsey, S. C.; Babiker, M. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Al-Amri, M. [Department of Physics, King Khalid Univeristy, P.O. Box 9003, Abha (Saudi Arabia); Juzeliunas, G. [Institute of Theoretical Physics and Astronomy of Vilnius University, A. Gostauto 12, 01108 Vilnius (Lithuania)

2006-01-15

90

Spontaneous emission lifetimes in the ground electronic states of HD/+/ and H2/+/a  

NASA Technical Reports Server (NTRS)

Because of their simplicity, H2(+) and its isotopic species are of particular interest to molecular theorists and experimentalists. If these ions are formed in excited vibrational states under conditions of highly improbable electron-ion recombination or other reactions, spontaneous emission will occur. The present note calculates the (vibrational quantum number, J prime = 0) state lifetimes under spontaneous emission for all 22 excited vibrations of HD(+) and all 19 excited vibrations of H2(+) in their ground electron states. The lifetimes presented in Tables I and III justify the assumption that spontaneous radiative processes are unimportant under certain realizable conditions. When spontaneous radiation plays a role, however, minimum lifetime at intermediate vibrational quantum number could lead to unusual vibrational distribution functions.

Peek, J. M.; Hashemi-Attar, A.-R.; Beckel, C. L.

1979-01-01

91

Strongly modified spontaneous emission rates in diamond-structured photonic crystals.  

PubMed

The spontaneous emission decay dynamics of nanocrystal quantum dots embedded into biotemplated titania photonic crystals with a diamond-based lattice are investigated. Modification of the decay rate of quantum dot emission over wide frequency bandwidths in the visible by the photonic crystals is observed. Frequency-dependent analysis reveals both inhibition and enhancement of emission with a radiative lifetime variation by more than a factor of 10. PMID:22107195

Jorgensen, Matthew R; Galusha, Jeremy W; Bartl, Michael H

2011-09-30

92

Strongly Modified Spontaneous Emission Rates in Diamond-Structured Photonic Crystals  

NASA Astrophysics Data System (ADS)

The spontaneous emission decay dynamics of nanocrystal quantum dots embedded into biotemplated titania photonic crystals with a diamond-based lattice are investigated. Modification of the decay rate of quantum dot emission over wide frequency bandwidths in the visible by the photonic crystals is observed. Frequency-dependent analysis reveals both inhibition and enhancement of emission with a radiative lifetime variation by more than a factor of 10.

Jorgensen, Matthew R.; Galusha, Jeremy W.; Bartl, Michael H.

2011-09-01

93

Dipole Spontaneous Emission Near Planar Anisotropic Layers with Hyperbolic Metamaterial Properties  

NASA Astrophysics Data System (ADS)

Analytical expressions were obtained for the rates of spontaneous emission of an atom (molecule) located near planar anisotropic layers with hyperbolic metamaterial properties. The distribution of the electric field excited by a dipole source in an anisotropic layer followed a complicated pattern. It was shown that the emission rate into the half-space behind the layers could exceed substantially the emission rate into the half-space in front of the layers.

Guzatov, D. V.

2014-07-01

94

The influence of density of modes on dark lines in spontaneous emission  

E-print Network

We study two distinct multi-level atomic models in which one transition is coupled to a Markovian reservoir, while another linked transition is coupled to a non-Markovian reservoir. We show that by choosing appropriately the density of modes of the non-Markovian reservoir the spontaneous emission to the Markovian reservoir is greatly altered. The existence of `dark lines' in the spontaneous emission spectrum in the Markovian reservoir due to the coupling to specific density of modes of the non-Markovian reservoir is also predicted.

E. Paspalakis; D. G. Angelakis; P. L. Knight

1999-06-24

95

Spontaneous emission spectra of optically pumped vertical-cavity surface-emitting lasers  

NASA Astrophysics Data System (ADS)

We study the spontaneous emission spectra of optically pumped vertical-cavity surface-emitting lasers (VCSELs) operating below threshold. By spatial and angular filtering of the spontaneous emission spectra we can relate the observed asymmetrical shape of these spectra to the subthreshold guiding properties of the VCSELs. We find a substantial difference between VCSELs with a thin gain medium, consisting of quantum wells, and VCSELs with a thick gain medium, consisting of bulk GaAs; this difference is explained by analyzing the relative weights of thermal index guiding and carrier-induced index anti-guiding.

Hendriks, R. F. M.; Willemsen, M. B.; van Exter, M. P.; Woerdman, J. P.; Weegels, L.; Gulden, K. H.; Moser, M.

1998-04-01

96

Electrically controllable spontaneous magnetism in nanoscale mixed phase multiferroics.  

PubMed

Magnetoelectrics and multiferroics present exciting opportunities for electric-field control of magnetism. However, there are few room-temperature ferromagnetic-ferroelectrics. Among the various types of multiferroics the bismuth ferrite system has received much attention primarily because both the ferroelectric and the antiferromagnetic orders are quite robust at room temperature. Here we demonstrate the emergence of an enhanced spontaneous magnetization in a strain-driven rhombohedral and super-tetragonal mixed phase of BiFeO?. Using X-ray magnetic circular dichroism-based photoemission electron microscopy coupled with macroscopic magnetic measurements, we find that the spontaneous magnetization of the rhombohedral phase is significantly enhanced above the canted antiferromagnetic moment in the bulk phase, as a consequence of a piezomagnetic coupling to the adjacent tetragonal-like phase and the epitaxial constraint. Reversible electric-field control and manipulation of this magnetic moment at room temperature is also shown. PMID:21407191

He, Q; Chu, Y-H; Heron, J T; Yang, S Y; Liang, W I; Kuo, C Y; Lin, H J; Yu, P; Liang, C W; Zeches, R J; Kuo, W C; Juang, J Y; Chen, C T; Arenholz, E; Scholl, A; Ramesh, R

2011-01-01

97

Advanced Emissions Control Development Program  

SciTech Connect

The primary objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (HAPs, or air toxics) from coal-fired boilers. This objective is being met by identifying ways to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPs), fabric filters (fabric filters), and wet flue gas desulfurization (wet FGD) systems. Development work initially concentrated on the capture of trace metals, hydrogen chloride, and hydrogen fluoride. Recent work has focused almost exclusively on the control of mercury emissions.

G. A. Farthing; G. T. Amrhein; G. A. Kudlac; D. A. Yurchison; D. K. McDonald; M. G. Milobowski

2001-03-31

98

Diesel electronic engine emission controls  

Microsoft Academic Search

Recent changes that make diesel emission control regulations more stringent have necessitated the design and implementation of new, more sophisticated engine control strategies. The implementation of these controls will begin with closed-loop electronic exhaust gas recirculation (EGR) valve control for the 1984 California diesel passenger vehicles and will continue into 1985 with the addition of injection pump timing controls for

1984-01-01

99

Effect of surface-plasmon polaritons on spontaneous emission and intermolecular energy-transfer rates in multilayered geometries  

SciTech Connect

We use a Green's tensor method to investigate the spontaneous emission rate of a molecule and the energy-transfer rate between molecules placed in two types of layered geometries: a slab geometry and a planar waveguide. We focus especially on the role played by surface-plasmon polaritons in modifying the spontaneous emission and energy-transfer rates as compared to free space. In the presence of more than one interface, the surface-plasmon polariton modes split into several branches, and each branch can contribute significantly to modifying the electromagnetic properties of atoms and molecules. Enhancements of several orders of magnitude both in the spontaneous emission rate of a molecule and the energy-transfer rate between molecules are obtained and, by tuning the parameters of the geometry, one has the ability to control the range and magnitude of these enhancements. For the energy-transfer rate interference effects between contributions of different plasmon-polariton branches are observed as oscillations in the distance dependence of this rate.

Marocico, C. A.; Knoester, J. [Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747 AG Groningen (Netherlands)

2011-11-15

100

Enhanced spontaneous emission in a photonic-crystal light-emitting diode  

Microsoft Academic Search

We report direct evidence of enhanced spontaneous emission in a photonic-crystal (PhC) light-emitting diode. The device consists of p-i-n heterojunction embedded in a suspended membrane, comprising a layer of self-assembled quantum dots. Current is injected laterally from the periphery to the center of the PhC. A well-isolated emission peak at 1.3 mum from the PhC cavity mode is observed, and

M. Francardi; LP Balet; A. Gerardino; NJG Chauvin; DJM Bitauld; L. H. Li; B. Alloing; A. Fiore

2008-01-01

101

Nonlocal effects: relevance for the spontaneous emission rates of quantum emitters coupled to plasmonic structures  

E-print Network

The spontaneous emission rate of dipole emitters close to plasmonic dimers are theoretically studied within a nonlocal hydrodynamic model. A nonlocal model has to be used since quantum emitters in the immediate environment of a metallic nanoparticle probe its electronic structure. Compared to local calculations, the emission rate is significantly reduced. The influence is mostly pronounced if the emitter is located close to sharp edges. We suggest to use quantum emitters to test nonlocal effects in experimentally feasible configurations.

Filter, Robert; Toscano, Giuseppe; Lederer, Falk; Rockstuhl, Carsten

2014-01-01

102

Nonlocal effects: relevance for the spontaneous emission rates of quantum emitters coupled to plasmonic structures  

NASA Astrophysics Data System (ADS)

The spontaneous emission rate of dipole emitters close to plasmonic dimers are theoretically studied within a nonlocal hydrodynamic model. A nonlocal model has to be used since quantum emitters in the immediate environment of a metallic nanoparticle probe its electronic structure. Compared to local calculations, the emission rate is significantly reduced. The influence is mostly pronounced if the emitter is located close to sharp edges. We suggest to use quantum emitters to test nonlocal effects in experimentally feasible configurations.

Filter, Robert; Bösel, Christoph; Toscano, Giuseppe; Lederer, Falk; Rockstuhl, Carsten

2014-11-01

103

Spontaneous Emission and Coupled-Mode Theory in Multimode 1-D Systems With Contradirectional Coupling  

Microsoft Academic Search

By means of source terms and coupled-mode theory, the essential features of spontaneous emission in multimode waveguides with counterdirectional feedback, such as corrugated and photonic crystal waveguides, are described in a heuristic manner. These multimode source terms generalize a similar ap- proach evoked in multilayer structures. We account for features such as the \\

Henri Benisty; Omer Khayam

2011-01-01

104

Interactions between Hair Cells Shape Spontaneous Otoacoustic Emissions in a Model of the Tokay Gecko's Cochlea  

Microsoft Academic Search

BackgroundThe hearing of tetrapods including humans is enhanced by an active process that amplifies the mechanical inputs associated with sound, sharpens frequency selectivity, and compresses the range of responsiveness. The most striking manifestation of the active process is spontaneous otoacoustic emission, the unprovoked emergence of sound from an ear. Hair cells, the sensory receptors of the inner ear, are known

Michael Gelfand; Oreste Piro; Marcelo O. Magnasco; A. J. Hudspeth; Vladimir Brezina

2010-01-01

105

Amplified spontaneous emission in graded-index polymer optical fibers: theory and experiment.  

PubMed

In this work we analyze experimentally and theoretically the properties of amplified spontaneous emission (ASE) in a rhodamine-6G-doped graded-index polymer optical fiber. A theoretical model based on the laser rate equations describes the ASE features successfully. The dependence of the ASE threshold and efficiency on fiber length is analyzed in detail. PMID:24104335

Illarramendi, M Asunción; Arrue, Jon; Ayesta, Igor; Jiménez, Felipe; Zubia, Joseba; Bikandi, Iñaki; Tagaya, Akihiro; Koike, Yasuhiro

2013-10-01

106

Effect of amplified spontaneous emission on semiconductor optical amplifier based all-optical logic  

NASA Astrophysics Data System (ADS)

The performances of all-optical logic gates XOR, AND, OR, NOR and NAND based on semiconductor optical amplifier (SOA) have been simulated including the effects of amplified spontaneous emission (ASE). For the parameters used, all-optical logic gates using SOA are capable of operating at speed of 80 Gb/s.

Kotb, A.; Ma, S.; Chen, Z.; Dutta, N. K.; Said, G.

2011-12-01

107

Thermalization of strongly interacting bosons after spontaneous emissions in optical lattices  

E-print Network

We study the out-of-equilibrium dynamics of bosonic atoms in a 1D optical lattice, after the ground-state is excited by a single spontaneous emission event, i.e. after an absorption and re-emission of a lattice photon. This is an important fundamental source of decoherence for current experiments, and understanding the resulting dynamics and changes in the many-body state is important for controlling heating in quantum simulators. Previously it was found that in the superfluid regime, simple observables relax to values that can be described by a thermal distribution on experimental time-scales, and that this breaks down for strong interactions (in the Mott insulator regime). Here we expand on this result, investigating the relaxation of the momentum distribution as a function of time, and discussing the relationship to eigenstate thermalization. For the strongly interacting limit, we provide an analytical analysis for the behavior of the system, based on an effective low-energy Hamiltonian in which the dynamics can be understood based on correlated doublon-holon pairs.

Johannes Schachenmayer; Lode Pollet; Matthias Troyer; Andrew J. Daley

2014-08-05

108

Plasmonic engineering of spontaneous emission from silicon nanocrystals  

PubMed Central

Silicon nanocrystals offer huge advantages compared to other semi-conductor quantum dots as they are made from an abundant, non-toxic material and are compatible with silicon devices. Besides, among a wealth of extraordinary properties ranging from catalysis to nanomedicine, metal nanoparticles are known to increase the radiative emission rate of semiconductor quantum dots. Here, we use gold nanoparticles to accelerate the emission of silicon nanocrystals. The resulting integrated hybrid emitter is 5-fold brighter than bare silicon nanocrystals. We also propose an in-depth analysis highlighting the role of the different physical parameters in the photoluminescence enhancement phenomenon. This result has important implications for the practical use of silicon nanocrystals in optoelectronic devices, for instance for the design of efficient down-shifting devices that could be integrated within future silicon solar cells. PMID:24037020

Goffard, Julie; Gérard, Davy; Miska, Patrice; Baudrion, Anne-Laure; Deturche, Régis; Plain, Jérôme

2013-01-01

109

Plasmonic engineering of spontaneous emission from silicon nanocrystals.  

PubMed

Silicon nanocrystals offer huge advantages compared to other semi-conductor quantum dots as they are made from an abundant, non-toxic material and are compatible with silicon devices. Besides, among a wealth of extraordinary properties ranging from catalysis to nanomedicine, metal nanoparticles are known to increase the radiative emission rate of semiconductor quantum dots. Here, we use gold nanoparticles to accelerate the emission of silicon nanocrystals. The resulting integrated hybrid emitter is 5-fold brighter than bare silicon nanocrystals. We also propose an in-depth analysis highlighting the role of the different physical parameters in the photoluminescence enhancement phenomenon. This result has important implications for the practical use of silicon nanocrystals in optoelectronic devices, for instance for the design of efficient down-shifting devices that could be integrated within future silicon solar cells. PMID:24037020

Goffard, Julie; Gérard, Davy; Miska, Patrice; Baudrion, Anne-Laure; Deturche, Régis; Plain, Jérôme

2013-01-01

110

Emission control system  

NASA Technical Reports Server (NTRS)

Methods and apparatus utilizing hydrogen peroxide are useful to reduce SOx and mercury (or other heavy metal) emissions from combustion flue gas streams. The methods and apparatus may further be modified to reduce NOx emissions. Continuous concentration of hydrogen peroxide to levels approaching or exceeding propellant-grade hydrogen peroxide facilitates increased system efficiency. In this manner, combustion flue gas streams can be treated for the removal of SOx and heavy metals, while isolating useful by-products streams of sulfuric acid as well as solids for the recovery of the heavy metals. Where removal of NOx emissions is included, nitric acid may also be isolated for use in fertilizer or other industrial applications.

Parrish, Clyde F. (Inventor); Chung, J. Landy (Inventor)

2009-01-01

111

ADVANCED EMISSIONS CONTROL DEVELOPMENT PROGRAM  

SciTech Connect

The objective of this project is to develop practical strategies and systems for the simultaneous control of SO{sub 2}, NO{sub x}, particulate matter, and air toxics emissions from coal-fired boilers in such a way as to keep coal economically and environmentally competitive as a utility boiler fuel. Of particular interest is the control of air toxics emissions through the cost-effective use of conventional flue gas clean-up equipment such as electrostatic precipitators (ESP's), fabric filters (baghouses), and SO{sub 2} removal systems such as wet scrubbers and various clean coal technologies. This objective will be achieved through extensive development testing in the state-of-the art, 10 MW{sub e} equivalent, Clean Environment Development Facility (CEDF). The project has extended the capabilities of the CEDF to facilitate air toxics emissions control development work on backend flue gas cleanup equipment. Specifically, an ESP, a baghouse, and a wet scrubber for SO{sub 2} (and air toxics) control were added--all designed to yield air toxics emissions data under controlled conditions, and with proven predictability to commercial systems. A schematic of the CEDF and the project test equipment is shown in Figure 1. The specific objectives of the project are to: (1) Measure and understand production and partitioning of air toxics species in coal-fired power plant systems; (2) Optimize the air toxics removal performance of conventional flue gas cleanup systems; (3) Quantify the impacts of coal cleaning on air toxics emissions; (4) Identify and/or develop advanced air toxics emissions control concepts; (5) Develop and validate air toxics emissions measurement and monitoring techniques; (6) Establish an air toxics data library to facilitate studies of the impacts of coal selection, coal cleaning, and emissions control strategies on the emissions of coal-fired power plants.

M.J. Holmes

1998-07-01

112

ADVANCED EMISSIONS CONTROL DEVELOPMENT PROGRAM  

SciTech Connect

The objective of this project is to develop practical strategies and systems for the simultaneous control of SO{sub 2}, NO{sub x}, particulate matter, and air toxics emissions from coal-fired boilers in such a way as to keep coal economically and environmentally competitive as a utility boiler fuel. Of particular interest is the control of air toxics emissions through the cost-effective use of conventional flue gas clean-up equipment such as electrostatic precipitators (ESP's), fabric filters (baghouses), and SO{sub 2} removal systems such as wet scrubbers and various clean coal technologies. This objective will be achieved through extensive development testing in the state-of-the art, 10 MW{sub e} equivalent, Clean Environment Development Facility (CEDF). The project has extended the capabilities of the CEDF to facilitate air toxics emissions control development work on backend flue gas cleanup equipment. Specifically, an ESP, a baghouse, and a wet scrubber for SO{sub 2} (and air toxics) control were added--all designed to yield air toxics emissions data under controlled conditions, and with proven predictability to commercial systems. A schematic of the CEDF and the project test equipment is shown in Figure 1. The specific objectives of the project are to: (1) Measure and understand production and partitioning of air toxics species in coal-fired power plant systems; (2) Optimize the air toxics removal performance of conventional flue gas cleanup systems; (3) Quantify the impacts of coal cleaning on air toxics emissions; (4) Identify and/or develop advanced air toxics emissions control concepts; (5) Develop and validate air toxics emissions measurement and monitoring techniques; (6) Establish an air toxics data library to facilitate studies of the impacts of coal selection, coal cleaning, and emissions control strategies on the emissions of coal-fired power plants.

M.J. Holmes

1999-01-01

113

ADVANCED EMISSIONS CONTROL DEVELOPMENT PROGRAM  

SciTech Connect

The objective of this project is to develop practical strategies and systems for the simultaneous control of SO{sub 2}, NO{sub x}, particulate matter, and air toxics emissions from coal-fired boilers in such a way as to keep coal economically and environmentally competitive as a utility boiler fuel. Of particular interest is the control of air toxics emissions through the cost-effective use of conventional flue gas clean-up equipment such as electrostatic precipitators (ESP's), fabric filters (baghouses), and SO{sub 2} removal systems such as wet scrubbers and various clean coal technologies. This objective will be achieved through extensive development testing in the state-of-the art, 10 MW{sub e} equivalent, Clean Environment Development Facility (CEDF). The project has extended the capabilities of the CEDF to facilitate air toxics emissions control development work on backend flue gas cleanup equipment. Specifically, an ESP, a baghouse, and a wet scrubber for SO{sub 2} (and air toxics) control were added--all designed to yield air toxics emissions data under controlled conditions, and with proven predictability to commercial systems. A schematic of the CEDF and the project test equipment is shown in Figure 1. The specific objectives of the project are to: (1) Measure and understand production and partitioning of air toxics species in coal-fired power plant systems; (2) Optimize the air toxics removal performance of conventional flue gas cleanup systems; (3) Quantify the impacts of coal cleaning on air toxics emissions; (4) Identify and/or develop advanced air toxics emissions control concepts; (5) Develop and validate air toxics emissions measurement and monitoring techniques; (6) Establish an air toxics data library to facilitate studies of the impacts of coal selection, coal cleaning, and emissions control strategies on the emissions of coal-fired power plants.

M.J. Holmes

1998-10-01

114

Nonresonant enhancement of spontaneous emission in metal-dielectric-metal plasmon waveguide structures  

SciTech Connect

We theoretically investigate the spontaneous emission process of an optical, dipolar emitter in metal-dielectric-metal slab and slot waveguide structures. We find that both structures exhibit strong emission enhancements at nonresonant conditions, due to the tight confinement of modes between two metallic plates. The large enhancement of surface plasmon-polariton excitation enables dipole emission to be preferentially coupled into plasmon waveguide modes. These structures find applications in creating nanoscale local light sources or in generating guided single plasmons in integrated optical circuits.

Jun, Y.C.

2010-03-02

115

Measurement of amplified spontaneous emission at 200 A  

SciTech Connect

Recent interest in the production of laser radiation at soft x-ray wavelengths makes appropriate the discussion of diagnostic considerations and techniques for the measurement of same. A source of soft x-ray ASE has a number of characteristics which drive the design of diagnostic instruments: (1) the anisotropy of the ASE makes target alignment a critical part of the diagnosis, and couples collection solid angle to S/N considerations in the measurement; (2) the narrow linewidth of the amplified emission and its long wavelength put a high S/N premium on spectroscopic instrumentation of high spectral resolution and good higher-order discrimination; (3) the specialized plasma conditions required to produce gain are typically short lived, requiring time-resolved or at least time-discriminating spectroscopy; (4) the nonlinear nature of the threshold processes involved in ASE requires instrumentation of large dynamic range, broad angular acceptance, and large field of view and depth of focus. Of the many possible methods for gain verification of the x-ray source, five are discussed: (1) probe amplification; (2) spatial coherence measurement (as a function of gain length); (3) output intensity measurement (absolute measurement and nonlinear variation with gain length); (4) divergence measurement; and (5) cavity formation. In addition, recent soft x-ray laser experiments at LLNL are discussed along with descriptions of the instruments used to measure the ASE. Diagnostic design suggestions for future soft x-ray laser experiments are also presented.

Ceglio, N.M.

1985-05-01

116

Emission control system  

NASA Technical Reports Server (NTRS)

Methods and apparatus utilizing hydrogen peroxide are useful to reduce NOx, SOx and mercury (or other heavy metal) emissions from combustion flue gas streams. Continuous concentration of hydrogen peroxide to levels approaching or exceeding propellant-grade hydrogen peroxide facilitates increased system efficiency. In this manner, combustion flue gas streams can be treated for the removal of NOx, SOx and heavy metals, while isolating useful by-products streams of sulfuric acid and nitric acid as well as solids for the recovery of the heavy metals.

Parrish, Clyde F. (Inventor)

2008-01-01

117

Advanced Emissions Control Development Program: Mercury Control  

SciTech Connect

McDermott Technology, Inc. (a subsidiary of Babcock & Wilcox) is conducting the Advanced Emissions Control Development Project (AECDP) which is aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (HAPS) from coal-fired electric utility plants. The need for such controls may arise as the US Environmental Protection Agency (EPA) proceeds with implementation of requirements set forth in the Clean Air Act Amendments (CAAA`s) of 1990. Promulgation of air toxics emissions regulations for electric utility plants could dramatically impact utilities burning coal, their industrial and residential customers, and the coal industry. AECDP project work will supply the information needed by utilities to respond to potential HAPs regulations in a timely, cost-effective, enviromnentally-sound manner which supports the continued use of the Nation`s abundant reserves of coal, such as those in the State of Ohio. The development work is being carried out using the 10 MW Clean Environment Development Facility wherein air toxics emissions control strategies can be developed under controlled conditions. The specific objectives of the project are to (1) measure and understand production and partitioning of air toxics species for a variety of coals, (2) optimize the air toxics removal performance of conventional flue gas cleanup systems, (3) develop advanced air toxics emissions control concepts, (4) develop and validate air toxics emissions measurement and monitoring techniques, and (5) establish a comprehensive, self-consistent air toxics data library. This project is supported by the Department of Energy, the Ohio Coal Development Office within the Ohio Department of Development and Babcock & Wilcox. A comprehensive assessment of HAP emissions from coal-fired electric utility boilers sponsored by the Department of Energy and the Electric Power Research Institute concluded that with the exception of selenium and mercury, the majority of trace elements are well controlled due to their association with the particulate phase of flue gas. Reflecting the current focus of the US EPA and state environmental agencies on mercury as a potential candidate for regulation, the project specifically targets the measurement and control of mercury species. This paper discusses the results of testing on the quantity and species distribution of mercury while firing Ohio high-sulfur coal to assess the mercury emissions control potential of conventional SO{sub 2} and particulate control systems. Results from recent AECDP tests are presented and two alternative mercury speciation methods are compared. The AECDP results clearly show that higher total mercury control efficiency can be achieved with a wet FGD scrubber than recently reported in the interim final US EPA report on HAP emissions from fossil-fired electric utility steam generating units.

Evans, A.P.; Redinger, K.W.; Holmes, M.J.

1997-07-01

118

Cooperative Spontaneous Emission from a Single-quantum Excited Three-atom System  

NASA Astrophysics Data System (ADS)

The total radiation rate of the cooperative spontaneous emission from an initially single-quantum excited three-atom system is calculated using Lehmberg's master equation and taking into account dipole-dipole near field interaction. We find a strong influence of the precise configuration of the atomic dipoles and of the position of the initially excited atom on the temporal behaviour of the total radiation rate, especially if the atoms are separated by distances much smaller than the resonance wavelength.Translated AbstractKooperative spontane Emission eines einfach angeregten Drei-Atom-SystemsEs wird die Gesamtintensität der spontanen Strahlung eines kooperativ emittierenden, anfänglich einfach angeregten Drei-Atom-Systems unter Berücksichtigung der Dipol-Dipol-Nahfeld-Wechselwirkung mit Hilfe der Lehmbergschen Mastergleichung berechnet. Ihr zeitlicher Verlauf hängt, insbesondere bei Atomabständen, die viel kleiner als die Resonanzwellenlänge sind, ganz wesentlich von der genauen Anordnung der atomaren Dipolmomente und von dem Ort des anfänglich angeregten Atoms ab.

Richter, Th.

119

The dynamics of amplified spontaneous emission in CdSe/ZnSe quantum dots  

E-print Network

We have used the variable stripe technique and pump-probe spectroscopy to investigate both gain and the dynamics of amplified spontaneous emission from CdSe quantum dot structures. We have found modal gain coefficients of 75 and 32 1/cm for asymmetric and symmetric waveguide structures, respectively. Amplified spontaneous emission decay times of 150 and 300 ps and carrier capture times of 15 and 40 ps were measured for the structures with high and low material gains respectively. The difference in the capture times are related to the fact that for the symmetric waveguide, carriers diffuse into the active region from the uppermost ZnMgSSe cladding layer, yielding a longer rise time for the pump-probe signals for this sample.

Kundys, D O; Wells, J P R; Tartakovskii, A I; Skolnick, M S; Dang, Le Si; Lutsenko, E V; Tarasuk, N P; Lyublinskaya, O G; Toropov, A A; Ivanov, S V

2014-01-01

120

Advanced Emissions Control Development Program  

SciTech Connect

The objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. Ideally, the project aim is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPS), fabric filters (baghouse), and wet flue gas desulfurization. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate and hydrogen chloride. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on the evaluation of mercury and several other air toxics emissions. The AECDP is jointly funded by the United States Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (oCDO), and Babcock& Wilcox-a McDermott company (B&W).

A.P.Evans; K.E. Redinger; M.J. Holmes

1998-04-01

121

Exponential Gain and Saturation of a Self-Amplified Spontaneous Emission Free-Electron Laser  

Microsoft Academic Search

Self-amplified spontaneous emission in a free-electron laser has been proposed for the generation of very high brightness coherent x-rays. This process involves passing a high-energy, high-charge, short-pulse, low-energy-spread, and low-emittance electron beam through the periodic magnetic field of a long series of high-quality undulator magnets. The radiation produced grows exponentially in intensity until it reaches a saturation point. We report

S. V. Milton; E. Gluskin; N. D. Arnold; C. Benson; W. Berg; S. G. Biedron; M. Borland; Y.-C. Chae; R. J. Dejus; P. K. Den Hartog; B. Deriy; M. Erdmann; Y. I. Eidelman; M. W. Hahne; Z. Huang; K.-J. Kim; J. W. Lewellen; Y. Li; A. H. Lumpkin; O. Makarov; E. R. Moog; A. Nassiri; V. Sajaev; R. Soliday; B. J. Tieman; E. M. Trakhtenberg; G. Travish; I. B. Vasserman; N. A. Vinokurov; X. J. Wang; G. Wiemerslage; B. X. Yang

2001-01-01

122

Spontaneous emission of a photon: Wave-packet structures and atom-photon entanglement  

Microsoft Academic Search

Spontaneous emission of a photon by an atom is described theoretically in three dimensions with the initial wave function of a finite-mass atom taken in the form of a finite-size wave packet. Recoil and wave-packet spreading are taken into account. The total atom-photon wave function is found in the momentum and coordinate representations as the solution of an initial-value problem.

M. V. Fedorov; M. A. Efremov; A. E. Kazakov; K. W. Chan; C. K. Law; J. H. Eberly

2005-01-01

123

Multilevel cooperative amplified spontaneous emission from the I/sub 2/(B. -->. X) system  

SciTech Connect

Amplified spontaneous emission (ASE) on the I/sub 2/(B..-->..X) system has been studied as a function of excitation wavelength by using a narrow-band pulsed dye-laser pump source. ASE output in the range 1.1--1.3 ..mu..m has been observed for dye-laser excitation wavelengths between 515 and 600 nm. Cooperative emission from several adjacent rotational levels has been observed and provides an explanation for anomalous spectral features. The conversion efficiency of dye-laser photons to ASE output was as high as a few percent. Pump energy thresholds as low as 5.0 ..mu..J were observed.

Glessner, J.W.; Davis, S.J.

1987-07-01

124

Advanced Emission Control Development Program.  

SciTech Connect

Babcock & Wilcox (B&W) is conducting a five-year project aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (commonly called air toxics) from coal-fired electric utility plants. The need for air toxic emissions controls may arise as the U. S. Environmental Protection Agency proceeds with implementation of Title III of the Clean Air Act Amendment (CAAA) of 1990. Data generated during the program will provide utilities with the technical and economic information necessary to reliably evaluate various air toxics emissions compliance options such as fuel switching, coal cleaning, and flue gas treatment. The development work is being carried out using B&W`s new Clean Environment Development Facility (CEDF) wherein air toxics emissions control strategies can be developed under controlled conditions, and with proven predictability to commercial systems. Tests conducted in the CEDF provide high quality, repeatable, comparable data over a wide range of coal properties, operating conditions, and emissions control systems. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate, and the inorganic species hydrogen chloride and hydrogen fluoride.

Evans, A.P.

1997-12-31

125

Numerical study of amplified spontaneous emission and lasing in random media  

SciTech Connect

We simulate the transition from amplified spontaneous emission (ASE) to lasing in random systems with varying degrees of mode overlap. This is accomplished by solving the stochastic Maxwell-Bloch equations with the finite-difference time-domain method. Below lasing threshold, the continuous emission spectra are narrowed by frequency-dependent amplification. Our simulations reproduce the stochastic emission spikes in the spectra. Well-defined peaks, corresponding to the system resonances, emerge at higher pumping and are narrowed by stimulated emission before lasing takes place. Noise tends to distribute pump energy over many modes, resulting in multimode operation. Well above the lasing threshold, the effects of noise lessen and results become similar to those without noise. By comparing systems of different scattering strength, we find that weaker scattering extends the transition region from ASE to lasing, where the effects of noise are most significant.

Andreasen, Jonathan [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Cao Hui [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States)

2010-12-15

126

Strong modification of quantum dot spontaneous emission via gap plasmon coupling in metal nanoslits  

SciTech Connect

A metal-dielectric-metal (MDM) waveguide with a nanoscale gap supports highly confined surface plasmon-polariton modes, termed gap plasmons. The spontaneous emission of an emitter placed in such a metal nanogap is expected to be strongly modified due to coupling to gap plasmons. We investigate the light emission properties of semiconductor quantum dots (QD) in a metal nanoslit, which is a truncated MDM waveguide. More specifically, we measure both the lifetime and the state of polarization of the out-coupled QD emission from a metal nanoslit. We observe clear lifetime and polarization changes of QD emission. As the slit width gets smaller, the QD exciton lifetime gradually decreases, and its emission becomes polarized normal to the slit, as expected for gap plasmon coupled light emission. We also find that the polarization of the collected QD emission is flipped (i.e., becomes parallel to a slit) when the excited emitters are located just outside the slit. We have conducted dipole emission calculations in metal nanoslits, and these explain the experimentally observed lifetime and polarization changes well. These findings may have novel applications in nanoscale optical sources, sensors, and active devices.

Jun, Y.C.

2010-02-24

127

Amplified spontaneous emission in optically pumped neat films of a polyfluorene derivative  

NASA Astrophysics Data System (ADS)

We report the emissive properties of a fluorene-based polymer, PF-1SOR, in planar asymmetric waveguides under optical pumping. A laser beam homogenizer setup was applied to achieve the flat-top intensity profile of the excitation light. Amplification of deep blue light via stimulated emission (SE) occurred at an energy threshold of 11 ?J cm -2 and the amplified spontaneous emission (ASE) peak could be tuned from 411 to 423 nm. A net gain coefficient of 19.8 cm -1 was obtained by means of the modified variable stripe length (VSL) method. The PF-1SOR thin films delivered a remarkably low loss coefficient of 1.5 cm -1, among the lowest ever reported for a single component polymer waveguide.

Li, Jiu Yan; Laquai, Frédéric; Wegner, Gerhard

2009-08-01

128

An erbium-doped 1-D fiber-Bragg grating and its effect upon erbium (3+) radiative spontaneous emission  

NASA Astrophysics Data System (ADS)

Spontaneous atomic emission is not a process of the isolated atom but rather a cooperative effect of the atom and the vacuum field. It is now well established that spontaneous radiative decay rates can be enhanced or suppressed through the effect of cavities comprising various types of discrete, reflective-mirror type, boundaries. The cavity effect is generally understood in terms of a cavity-induced modification of the vacuum spectral energy density. Recently, interest has grown in the possibility that systems characterized by distributed periodic boundary conditions, such as a spatially varying index of refraction, might be effective in controlling radiative atomic processes. A semi-classical theory is given that enables an estimate of the size of the lifetime modification of a two-level radiator contained within a three-dimensionally incomplete photonic bandgap structure called a fiber-Bragg grating. Following this is an exploration of a specific system and its effect upon radiative spontaneous emission. It is found through fluorescence line narrowing and frequency hole burning measurements that the observation of lifetime modification of the specific system is complicated due to intra and inter Stark energy migration. A lifetime modification measurement then shows that no change in lifetime is observed beyond the error bars on the measurement results. The tuning and coherence properties of a short-external-cavity diode laser that may be useful for future time-dependent spectroscopic measurements are examined using a fiber-based, self-heterodyne technique. Coherence properties during active frequency scans are characterized through analysis of time-dependent heterodyne beat signals at the output of a fiber interferometer.

Boggs, Bryan S.

129

An active oscillator model describes the statistics of spontaneous otoacoustic emissions.  

PubMed

Even in the absence of external stimulation, the cochleas of most humans emit very faint sounds below the threshold of hearing, sounds that are known as spontaneous otoacoustic emissions. They are a signature of the active amplification mechanism in the cochlea. Emissions occur at frequencies that are unique for an individual and change little over time. The statistics of a population of ears exhibit characteristic features such as a preferred relative frequency distance between emissions (interemission intervals). We propose a simplified cochlea model comprising an array of active nonlinear oscillators coupled both hydrodynamically and viscoelastically. The oscillators are subject to a weak spatial disorder that lends individuality to the simulated cochlea. Our model captures basic statistical features of the emissions: distributions of 1), emission frequencies; 2), number of emissions per ear; and 3), interemission intervals. In addition, the model reproduces systematic changes of the interemission intervals with frequency. We show that the mechanism for the preferred interemission interval in our model is the occurrence of synchronized clusters of oscillators. PMID:25140416

Fruth, Florian; Jülicher, Frank; Lindner, Benjamin

2014-08-19

130

Thickness dependence of amplified spontaneous emission in low-absorbing organic waveguides.  

PubMed

The effect of varying film thickness (h) on the amplified spontaneous emission (ASE) properties of 0.5??wt.% perylenediimide-doped polystyrene waveguides is reported. The threshold dependence on h, not previously investigated in detail, is analyzed in terms of the film absorption and photoluminescence, the confinement of the fundamental waveguide mode (TE0), and the presence of high-order modes. For h<400??nm and down to 150 nm, the ASE wavelength blueshifts, while the linewidth and threshold increase. The detrimental ASE operation in very thin films is due to the low absorption as well as to the poor confinement of the TE0 mode. PMID:22695562

Calzado, Eva M; Ramírez, Manuel G; Boj, Pedro G; Díaz García, María A

2012-06-01

131

Direct observation of amplified spontaneous emission of surface plasmon polaritons at metal/dielectric interfaces  

NASA Astrophysics Data System (ADS)

We report on direct observation of amplified spontaneous emission (ASE) of surface plasmon polaritons (SPPs) at the interface of a silver film and a gain medium. Based on a typical Kretschmann configuration incorporated with Rhodamine 6G molecules, the growing ASE spectra of SPPs have been clearly identified by carefully conducting a pump-dependent angle-resolved spectral measurement. Spectral narrowing effects induced by the SPP amplification are also demonstrated. The observed phenomena are helpful in understanding the fundamental interactions between SPPs and gain medium, which could enable wide applications on plasmonic sources and sensors.

Chen, Yu-Hui; Li, Jiafang; Ren, Ming-Liang; Wang, Ben-Li; Fu, Jin-Xin; Liu, Si-Yun; Li, Zhi-Yuan

2011-06-01

132

Unifying intensity noise and second-order coherence properties of amplified spontaneous emission sources  

NASA Astrophysics Data System (ADS)

We present joint investigations of relative intensity noise (RIN) and second-order coherence properties of amplified spontaneous emission (ASE) generated by a superluminescent diode. We introduce a generalized intensity noise description for ASE sources that contains the shot noise contribution but also accounts for first- and second-order coherence properties reflecting the process of light generation. We find excellent agreement between pump-current-dependent RIN values and this new description, with the perspective of particular interesting consequences for the realization of low-noise broadband emitters.

Blazek, Martin; Hartmann, Sébastien; Molitor, Andreas; Elsaesser, Wolfgang

2011-09-01

133

Cavity-induced coherence effects in spontaneous emission from pre-Selection of polarization  

E-print Network

Spontaneous emission can create coherences in a multilevel atom having close lying levels, subject to the condition that the atomic dipole matrix elements are non-orthogonal. This condition is rarely met in atomic systems. We report the possibility of bypassing this condition and thereby creating coherences by letting the atom with orthogonal dipoles to interact with the vacuum of a pre-selected polarized cavity mode rather than the free space vacuum. We derive a master equation for the reduced density operator of a model four level atomic system, and obtain its analytical solution to describe the interference effects. We report the quantum beat structure in the populations.

Anil K. Patnaik; G. S. Agarwal

1998-10-16

134

Amplified spontaneous emission of Rhodamine 6G embedded in pure deoxyribonucleic acid  

NASA Astrophysics Data System (ADS)

Deoxyribonucleic acid (DNA) is commonly viewed as a genetic information carrier. However, now it is recognized as a nanomaterial, rather than as a biological material, in the research field of nanotechnology. Here, we show that using pure DNA, doped with rhodamine 6G, we are able to observe amplified spontaneous emission (ASE) phenomenon. Moderate ASE threshold, photodegradation, and reasonable gain coefficient observed in this natural host gives some perspectives for practical applications of this system in biophotonics. Obtained results open the way and will be leading to construction of truly bio-lasers using nature made luminophores, such as anthocyanins.

Rau, Ileana; Szukalski, Adam; Sznitko, Lech; Miniewicz, Andrzej; Bartkiewicz, Stanislaw; Kajzar, Francois; Sahraoui, Bouchta; Mysliwiec, Jaroslaw

2012-10-01

135

Transverse amplified spontaneous emission: The limiting factor for output energy of ultra-high power lasers  

NASA Astrophysics Data System (ADS)

For the new generation of the ultra-high power lasers with tens of PW of output power, kJ-level energies have to be reached. Our modeling, applied to Ti:sapphire amplifiers, demonstrates for the first time, according our knowledge, that Transverse Amplified Spontaneous Emission (TASE) places an additional restriction on storing and extracting energy in larger gain apertures, even stronger than transverse parasitic generation (TPG). Nevertheless, we demonstrate that extracting during pumping (EDP) can significantly reduce parasitic losses due to both TASE and TPG.

Chvykov, Vladimir; Nees, John; Krushelnick, Karl

2014-02-01

136

Local field corrections to the spontaneous emission in arrays of Si nanocrystals  

E-print Network

We present a theory of the local field corrections to the spontaneous emission rate for the array of silicon nanocrystals in silicon dioxide. An analytical result for the Purcell factor is obtained. We demonstrate that the local-field corrections are sensitive to the volume fill factor of the nanocrystals in the sample and are suppressed for large values of the fill factor. The local-field corrections and the photonic density of states are shown to be described by two different effective permittivities: the harmonic mean between the nanocrystal and the matrix permittivities and the Maxwell-Garnett permittivity.

Poddubny, Alexander N

2014-01-01

137

Observation of self-amplified spontaneous emission in the near-infrared and visible wavelengths M. Babzien,1  

E-print Network

Observation of self-amplified spontaneous emission in the near-infrared and visible wavelengths M filter, were focused onto a silicon photodiode. Enhancement of the emissions, from 2 to 6 times cutoff characteristic of wake fields , and beam plasma frequency is not great. In far infrared wavelength

Wurtele, Jonathan

138

Multiphoton absorption induced amplified spontaneous emission from biocatalyst-synthesized ZnO nanorods  

NASA Astrophysics Data System (ADS)

Multiphoton absorption-induced photoluminescence and amplified spontaneous emission (ASE) have been observed from ZnO nanorod arrays upon near-infrared excitation (?exc˜800nm). A low threshold of ˜12mJ/cm2 was demonstrated for the ASE process. The ultraviolet emission can be attributed to the recombination of carriers coexcited by the processes of three-photon and off-resonant two-photon absorption, which was confirmed by the excitation wavelength-dependent experiments. Additionally, it has been observed that the processes of ASE and second harmonic generation in ZnO nanorods appear to enhance each other when the excitation wavelength approaches the resonant wavelength for two-photon absorption.

Zhang, Chunfeng; Zhang, Fan; Qian, Shixiong; Kumar, Nitin; Hahm, Jong-in; Xu, Jian

2008-06-01

139

USER'S GUIDE: EMISSION CONTROL TECHNOLOGIES AND EMISSION FACTORS FOR UNPAVED ROAD FUGITIVE EMISSIONS  

EPA Science Inventory

This document assists control agency personnel in evaluating unpaved road fugitive emissions control plans and helps industry personnel develop effective control strategies for unpaved roads. he brochure describes control techniques for reducing unpaved road emissions and methods...

140

Amplified spontaneous emission (ASE) models and approximations for thin-disk laser modeling  

NASA Astrophysics Data System (ADS)

It is well-known that amplified spontaneous emission (ASE) can be a major source of upper laser level loss in high gain pulsed or steady-state solid state lasers. This paper briefly reviews the theory of ASE and, using a simple rate equation model of the upper laser level, a geometric, radiative transport equation to describe the ASE intensity, and the perturbation method of multiple time scales, demonstrates that the loss rate of the upper laser level due to ASE adiabatically follows the spontaneous emission source term. This result which includes gain saturation is applicable to both quasi-three level and four level lasers and rigorously justifies formally using the steady-state expression derived heuristically by Lowenthal and Eggleston1 to model ASE loss in pulsed laser media. Then, it is shown that the frequency integral occurring in the ASE loss term can be evaluated analytically for both a broad "flat-top" and a Lorentzian stimulated emission lineshape but must be evaluated numerically or using an approximation due to Tommasini and Balmer2 for a Gaussian stimulated emission lineshape. It is shown that at high gain loss due to ASE is mitigated by ASE line narrowing. For a thin disk laser an approximate expression for the rate of ASE loss (or ASE lifetime) can be obtained by evaluating the remaining volume integral using either the method of Speiser3 or of Vretenar et al4. A new approximate expression for the ASE loss rate is obtained which, unlike Speiser's3 expression, accounts for ASE line narrowing and, unlike Vretenar et al's4 expression, correctly scales with the cylindrical volume of the disk. Application to both 1D and 3D laser modeling is briefly discussed.

Copeland, Drew A.

2013-03-01

141

Brillouin optical correlation domain analysis with 4 millimeter resolution based on amplified spontaneous emission.  

PubMed

A new technique for Brillouin scattering-based, distributed fiber-optic measurements of temperature and strain is proposed, analyzed, simulated, and demonstrated. Broadband Brillouin pump and signal waves are drawn from the filtered amplified spontaneous emission of an erbium-doped fiber amplifier, providing high spatial resolution. The reconstruction of the position-dependent Brillouin gain spectra along 5 cm of a silica single-mode fiber under test, with a spatial resolution of 4 mm, is experimentally demonstrated using a 25 GHz-wide amplified spontaneous emission source. A 4 mm-long localized hot spot is identified by the measurements. The uncertainty in the reconstruction of the local Brillouin frequency shift is ± 1.5 MHz. The single correlation peak between the pump and signal is scanned along a fiber under test using a mechanical variable delay line. The analysis of the expected spatial resolution and the measurement signal-to-noise ratio is provided. The measurement principle is supported by numerical simulations of the stimulated acoustic field as a function of position and time. Unlike most other Brillouin optical correlation domain analysis configurations, the proposed scheme is not restricted by the bandwidth of available electro-optic modulators, microwave synthesizers, or pattern generators. Resolution is scalable to less than one millimeter in highly nonlinear media. PMID:24921326

Cohen, Raphael; London, Yosef; Antman, Yair; Zadok, Avi

2014-05-19

142

On the spontaneous emission of electromagnetic radiation in the CSL model  

E-print Network

Spontaneous photon emission in the Continuous Spontaneous Localization (CSL) model is studied one more time. In the CSL model each particle interacts with a noise field that induces the collapse of its wave function. As a consequence of this interaction, when the particle is electrically charged, it radiates. As discussed in [1], the formula for the emission rate, to first perturbative order, contains two terms: One is proportional to the Fourier component of the noise field at the same frequency as that of the emitted photon and one is proportional to the zero Fourier component of the noise field. As discussed in previous works, this second term seems unphysical. In [1], it was shown that the unphysical term disappears when the noises is confined to a bounded region and the final particle's state is a wave packet. Here we investigate the origin of the unphysical term and why it vanishes according to the previous prescription. For this purpose, the electrodynamic part of the equation of motion is solved exactly while the part due to the noise is treated perturbatively. We show that the unphysical term is connected to exponentially decaying function of time which dies out in the large time limit, however, approximates to 1 in the first perturbative order in the electromagnetic field.

S. Donadi; A. Bassi; D. -A. Deckert

2013-07-03

143

Effects of low-frequency biasing on spontaneous otoacoustic emissions: frequency modulation.  

PubMed

It was previously reported that low-frequency biasing of cochlear structures can suppress and modulate the amplitudes of spontaneous otoacoustic emissions (SOAEs) in humans [Bian, L. and Watts, K. L. (2008). "Effects of low-frequency biasing on spontaneous otoacoustic emissions: Amplitude modulation," J. Acoust. Soc. Am. 123, 887-898]. In addition to amplitude modulation, the bias tone produced an upward shift of the SOAE frequency and a frequency modulation. These frequency effects usually occurred prior to significant modifications of SOAE amplitudes and were dependent on the relative strength of the bias tone and a particular SOAE. The overall SOAE frequency shifts were usually less than 2%. A quasistatic modulation pattern showed that biasing in either positive or negative pressure direction increased SOAE frequency. The instantaneous SOAE frequency revealed a "W-shaped" modulation pattern within one biasing cycle. The SOAE frequency was maximal at the biasing extremes and minimized at the zero crossings of the bias tone. The temporal modulation of SOAE frequency occurred with a short delay. These static and dynamic effects indicate that modifications of the mechanical properties of the cochlear transducer could underlie the frequency shift and modulation. These biasing effects are consistent with the suppression and modulation of SOAE amplitude due to shifting of the cochlear transducer operating point. PMID:19045788

Bian, Lin

2008-11-01

144

On the spontaneous emission of electromagnetic radiation in the CSL model  

NASA Astrophysics Data System (ADS)

Spontaneous photon emission in the Continuous Spontaneous Localization (CSL) model is studied one more time. In the CSL model each particle interacts with a noise field that induces the collapse of its wave function. As a consequence of this interaction, when the particle is electrically charged, it radiates. As discussed in Adler (2013) the formula for the emission rate, to first perturbative order, contains two terms: one is proportional to the Fourier component of the noise field at the same frequency as that of the emitted photon and one is proportional to the zero Fourier component of the noise field. As discussed in previous works, this second term seems unphysical. In Adler (2013) it was shown that the unphysical term disappears when the noise is confined to a bounded region and the final particle's state is a wave packet. Here we investigate the origin of this unphysical term and why it vanishes according to the previous prescription. We will see that perturbation theory is formally not valid in the large time limit since the effect of the noise accumulates continuously in time. Therefore either one performs an exact calculation (or at least in some way includes higher order terms) as we do here, or one finds a way to make a perturbative calculation meaningful, e.g., by confining the system as in Adler (2013).

Donadi, Sandro; Deckert, Dirk-André; Bassi, Angelo

2014-01-01

145

Collective spontaneous emission in coupled quantum dots: Physical mechanism of quantum nanoantenna  

NASA Astrophysics Data System (ADS)

We investigate the collective spontaneous emission in a system of two identical quantum dots (QDs) strongly coupled through the dipole-dipole (d-d) interaction. The QDs are modeled as two-level quantum objects, while the d-d interaction is described as the exchange of a virtual photon through the photonic reservoir. The master equation approach is used in the analysis. The main attention is focused on antenna characteristics of the two-QD system—the radiation intensity dependence on the meridian and azimuthal angles of observation. We show that the radiation pattern of such a system is nonstationary and its temporal behavior depends on the initial quantum state. In particular, for entangled initial states the radiative pattern exhibits oscillations on the frequency which corresponds to the d-d interaction energy. We also analyze spectral properties of the directional diagram. The comparison of radiation patterns is carried out for two QDs and two classical dipoles. The concept of quantum nanoantenna is proposed based on collective spontaneous emission in QD ensembles.

Mokhlespour, Salman; Haverkort, J. E. M.; Slepyan, Gregory; Maksimenko, Sergey; Hoffmann, A.

2012-12-01

146

Investigation of the spontaneous emission rate of perylene dye molecules encapsulated into three-dimensional nanofibers via FLIM method  

NASA Astrophysics Data System (ADS)

The decay dynamics of perylene dye molecules encapsulated in polymer nanofibers produced by electrospinning of polymethyl methacrylate are investigated using a confocal fluorescence lifetime imaging microscopy technique. Time-resolved experiments show that the fluorescence lifetime of perylene dye molecules is enhanced when the dye molecules are encapsulated in a three-dimensional photonic environment. It is hard to produce a sustainable host with exactly the same dimensions all the time during fabrication to accommodate dye molecules for enhancement of spontaneous emission rate. The electrospinning method allows us to have a control over fiber diameter. It is observed that the wavelength of monomer excitation of perylene dye molecules is too short to cause enhancement within nanofiber photonic environment of 330 nm diameters. However, when these nanofibers are doped with more concentrated perylene, in addition to monomer excitation, an excimer excitation is generated. This causes observation of the Purcell effect in the three-dimensional nanocylindrical photonic fiber geometry.

Acikgoz, Sabriye; Demir, Mustafa M.; Yapasan, Ece; Kiraz, Alper; Unal, Ahmet A.; Inci, M. Naci

2014-09-01

147

Cooperative Spontaneous Emission from an Initially Fully Excited System of Three Identical Two-level Atoms  

NASA Astrophysics Data System (ADS)

Using Lehmberg's master equation and taking into account dipole-dipole near-field interaction the time-dependent intensity pattern, intensity - and angular correlations of the cooperative spontaneous radiation from an initially fully excited system of three identical two-level atoms are calculated. The intensity pattern developes lobes in different directions at different times in such a way that contrary to the two-atom system the spatial distribution of the total number of the emitted photons differs from that of the single-atom radiation pattern. In particular three atoms placed in proper distances on a straight line emit preferentially their energy along this line. At the beginning of the emission process the probability to find two photons simultaneously in the same (or geometrical equivalent) direction is always highest but in the course of time, contrary to the two-atom case, it may well happen that the probability of finding two photons in quite different directions becomes more favoured.Translated AbstractKooperative spontane Emission eines anfänglich vollstandig angeregten Systems von drei gleichen Zwei-Niveau-AtomenEs werden der richtungsabhängige Intensitäts-Zeit-Verlauf sowie die Intensitäts- und Winkelkorrelationen der spontanen Strahlung eines kooperativ emittierenden, anfänglich vollständig angeregten Systems von drei gleichen Zwei-Niveau-Atomen mit Hilfe der Lehmbergschen Mastergleichung unter Berücksichtigung der Dipol-Dipol-Nahfeldwechselwirkung berechnet. Die Richtcharakteristik der Intensität zeigt zu verschiedenen Zeiten Keulen in unterschiedlichen Richtungen derart, daß im Gegensatz zum Zwei-Atomfall die Richtungsverteilung der insgesamt emittierten Photonen von der Ein-Atomrichtcharakteristik abweicht.Insbesondere strahlen drei, in geeignetem Abstand auf einer Geraden angeordnete Atome vorzugsweise in Richtung der Verbindungslinie. Zu Beginn des Ausstrahlungsprozesses ist die Wahrscheinlichkeit, zwei Photonen gleichzeitig in derselben (bzw. geometrisch äquivalenten) Richtung zu finden, immer am größten. Im Verlauf der Zeit kann es jedoch im Gegensatz zum Zwei-Atomsystem dazu kommen, daß die simultane Emission zweier Photonen in völlig verschiedene Richtungen bevorzugt ist.

Richter, Th.

148

Nonlinear resonance: Determining maximal autoresonant response and modulation of spontaneous otoacoustic emissions  

NASA Astrophysics Data System (ADS)

Sustained resonance in a linear oscillator is achievable with a drive whose constant frequency matches the resonant frequency of the oscillator. In oscillators with nonlinear restoring forces, i.e., Duffing-type oscillators, resonant frequency changes with amplitude, so a constant frequency drive generates a beat oscillation instead of sustained resonance. Duffing-type oscillators can be driven into sustained resonance, called autoresonance (AR), when drive frequency is swept in time to match the changing resonant frequency of the oscillator. It is found that near-optimal drive linear sweep rates for autoresonance can be estimated from the beat oscillation resulting from constant frequency excitation. Specifically, a least squares estimate of the slope of the Teager-Kaiser instantaneous frequency versus time plot for the rising half-cycle of the beat response to a stationary drive provides a near-optimal estimate of the linear drive sweep rate that sustains resonance in the pendulum, Duffing and Duffing-Van der Pol oscillators. These predictions are confirmed with model-based numerical simulations. A closed-form approximation to the AM-FM nonlinear resonance beat response of a Duffing oscillator driven at its low-amplitude oscillator frequency is obtained from a solution to an associated Mathieu equation. AR time responses are found to evolve along a Mathieu equation primary resonance stability boundary. AR breakdown occurs at sweep rates just past optimal and map to a single stable point just off the Mathieu equation primary resonance stability boundary. Optimal AR sweep rates produce oscillating phase differences with extrema near 90 degrees, allowing extended time in resonance. AR breakdown occurs when phase difference equals 180 degrees. Nonlinear resonance of the van der Pol type may play a role in the extraordinary sensitivity of the human ear. The mechanism for maintaining the cochlear amplifier at its critical point is currently unknown. The possibility of open-loop control of cochlear operating point, maintaining criticality on average through periodically varying damping (super-regeneration) motivates a study of spontaneous otoacoustic emission (SOAE) amplitude modulation on a short (msec) time scale. An example of periodic amplitude modulation within a wide filter bandwidth is found that appears to be a beat oscillation of two SOAEs.

Witkov, Carey

149

Emissions from modern passenger cars with malfunctioning emissions controls  

SciTech Connect

Malfunctioning emission controls continue to be a major source of emissions from in-use vehicles. The authors analyze two sources of data on cars with malfunctioning emissions controls: remote sensing surveys and dynamometer tests of cars in the condition they were received. The analysis indicates that roughly 8% of relatively new (2- to 5-year old), modern technology (fuel-injected) cars have malfunctioning emission controls. There is a wide range in the probability of malfunction of specific models, from zero to over 20%. Possible causes of high model-specific malfunction probability are poor initial design and/or manufacture.

Wenzel, T. [Lawrence Berkeley National Lab., CA (United States); Ross, M. [Univ. of Michigan, Ann Arbor, MI (United States)

1996-09-01

150

Final LDRD report : enhanced spontaneous emission rate in visible III-nitride LEDs using 3D photonic crystal cavities.  

SciTech Connect

The fundamental spontaneous emission rate for a photon source can be modified by placing the emitter inside a periodic dielectric structure allowing the emission to be dramatically enhanced or suppressed depending on the intended application. We have investigated the relatively unexplored realm of interaction between semiconductor emitters and three dimensional photonic crystals in the visible spectrum. Although this interaction has been investigated at longer wavelengths, very little work has been done in the visible spectrum. During the course of this LDRD, we have fabricated TiO{sub 2} logpile photonic crystal structures with the shortest wavelength band gap ever demonstrated. A variety of different emitters with emission between 365 nm and 700 nm were incorporated into photonic crystal structures. Time-integrated and time-resolved photoluminescence measurements were performed to measure changes to the spontaneous emission rate. Both enhanced and suppressed emission were demonstrated and attributed to changes to the photonic density of states.

Fischer, Arthur Joseph; Subramania, Ganapathi S.; Coley, Anthony J.; Lee, Yun-Ju; Li, Qiming; Wang, George T.; Luk, Ting Shan; Koleske, Daniel David; Fullmer, Kristine Wanta

2009-09-01

151

Comparison of the classical rate and the Einstein coefficient for spontaneous emission in a light-absorbing cavity  

SciTech Connect

The rate of spontaneous electromagnetic emission in a cavity is the normalized output radiation rate in the classical electrodynamics and the Einstein A coefficient in a quantum theory. We reveal the difference and similarity between the quantum and classical rates by calculations of the relative output power of the resonant spontaneous electric-dipole emission as a function of light absorption in a high-Q cavity. We show that the relative resonant output power is equal to the relative width of a morphology-dependent resonance in the spectral dependence of the Einstein A coefficient. The validity of the theory is demonstrated by numerical verification of an experimental result on a microsphere.

Datsyuk, Vitaly V.; Juodkazis, Saulius; Misawa, Hiroaki [CREST-JST and Research Institute for Electronic Science, Hokkaido University, N21-W10 CRIS Bldg., Sapporo 001-0021 (Japan)

2005-08-15

152

Amplified spontaneous emission and superradiant pulse from the flash-pumped atomic iodine system  

SciTech Connect

A superradiant and amplified spontaneous transition pulse is obtained from an iodine photodissociation laser amplifier which uses i-C/sub 3/F/sub 7/I as an active molecule and is pumped with a flashlamp (full width at half maximum = 3 ..mu..s). We have observed a sharp leading pulse of superradiance whose rise time is less than 50 ns, and the amplified spontaneous emission follows the superradiance during the pumping flash. By measuring the population inversion density in the active medium of the amplifier, we have obtained the threshold condition for the superradiance to take place. Also, the buildup time and peak intensity of the pulse are measured as a function of the flashlamp input energy. By placing a reflecting mirror at a varying distance (from 173 to 673 cm) behind the amplifier, we have found a periodic intensity fluctuation in the superradiance; the period (..delta..t) depends linearly on the distance (d), i.e., ..delta..t = 2d/c, where c is the light velocity.

Kim, G.U.; Lee, S.S.; Hahn, J.W.

1988-01-15

153

On the Theory of Spontaneous Emission by a Single Atom Located in an Ideal Cavity  

NASA Astrophysics Data System (ADS)

With the help of the well-known eigenfunctions for a two-level system coupled to a single mode of the radiation field, the correlation functions for both the atomic dipole and the electric field oscillation are calculated, in rotating-wave approximation, for an atom emitting spontaneously into an ideal cavity. Using the Eberly-Wódkiewicz formalism, the corresponding spectra are evaluated in the long-time, narrow-band detection limit. The two spectra exhibit the same Rabi splitting, but the ratio of the strengths of the two lines is significantly different, in the off-resonance case, for the dipole and the field oscillation.Translated AbstractZur Theorie der spontanen Emission eines in einem idealen Resonator befindlichen AtomsMit Hilfe der bekannten Eigenfunktionen für ein an eine einzige Eigenschwingung des Strahlungsfeldes gekoppeltes Zwei-Niveau-System wird die Korrelationsfunktion für sowohl die Dipolschwingung als auch die Schwingung der elektrischen Feldstärke in der rotatingwave-Näherung für ein Atom berechnet, das spontan in einen Resonator ausstrahlt. Unter Verwendung des Formalismus von Eberly und Wódkiewicz werden die entsprechenden Spektren für den Grenzfall langer Beobachtungszeit und schmalbandigen Nachweises ermittelt. Die beiden Spektren zeigen die gleiche Rabi-Aufspaltung, doch das Verhältnis der Stärke der zwei Linien unterscheidet sich im Nichtresonanzfall deutlich für die Dipol- und die Feldschwingung.

Paul, H.

154

Temporal phase mask encrypted optical steganography carried by amplified spontaneous emission noise.  

PubMed

A temporal phase mask encryption method is proposed and experimentally demonstrated to improve the security of the stealth channel in an optical steganography system. The stealth channel is protected in two levels. In the first level, the data is carried by amplified spontaneous emission (ASE) noise, which cannot be detected in either the time domain or spectral domain. In the second level, even if the eavesdropper suspects the existence of the stealth channel, each data bit is covered by a fast changing phase mask. The phase mask code is always combined with the wide band noise from ASE. Without knowing the right phase mask code to recover the stealth data, the eavesdropper can only receive the noise like signal with randomized phase. PMID:24515055

Wu, Ben; Wang, Zhenxing; Shastri, Bhavin J; Chang, Matthew P; Frost, Nicholas A; Prucnal, Paul R

2014-01-13

155

Amplified spontaneous emission in narrow-band pulsed dye laser oscillators--theory and experiment  

SciTech Connect

We have investigated the effect of amplified spontaneous emission (ASE) on the spectral and temporal characteristics of narrowband pulsed dye laser oscillators. The space and time dependent rate equations for the molecular populations and photon fluxes have been solved numberically to study the dependence of ASE on various laser parameters and the effects of ASE on the spectral and temporal profile of the dye laser output. To account for the diffraction losses present in a real dye laser oscillator, appropriate feedback factors for the laser and ASE photon fluxes were introduced into the boundary conditions for the oscillator. These theoretical results have been substantiated by experimental measurements of ASE in a narrow-band pulsed dye laser oscillator. We show that a considerable reduction of ASE in a grazing incidence grating dye laser oscillator can be obtained by appropriately shaping the pump pulse. Oscillations observed in the temporal output of pulsed dye lasers are also discussed.

Nair, L.G.; Dasgupta, K.

1985-11-01

156

Spatially-selective amplified spontaneous emission source derived from an ultrahigh gain solid-state amplifier.  

PubMed

An investigation is made into the performance of a high power solid-state amplified spontaneous emission (ASE) source with near-diffraction-limited beam quality. The radiation from this ASE source has high spatial quality and power, but unlike a laser it has a high misalignment tolerance and does not require a precisely aligned cavity. The source is based on a diode-pumped Nd:YVO4 laser crystal in a bounce amplifier geometry with a uniquely ultra-high gain (~104-105). Double-pass ASE radiation with high power levels (>6W) is achieved in a near-diffraction-limited spatial quality. We further demonstrate that the double-pass ASE source also displays high spatial selectivity and capability to compensate for a phase diffuser, inserted in the double-pass arm, with only a small degradation in beam quality and power. PMID:19516475

Smith, G; Damzen, M J

2006-04-17

157

High-power near-diffraction-limited solid-state amplified spontaneous emission laser devices.  

PubMed

We present investigations into high-power scaling of solid-state amplified spontaneous emission (ASE) laser sources by use of two high-gain (~10(4)) Nd:YVO(4) bounce amplifiers. The sources deliver high power with a high-quality spatial output, but unlike a laser they have a high misalignment tolerance and do not require a precisely aligned cavity. In one system with two amplifiers, we demonstrate an ASE source with 24.5W of output power with good spatial quality, M(2)<2.5 in the horizontal and M(2)<1.2 in the vertical. In a more sophisticated setup, the two amplifiers are arranged in a loop configuration producing 30W of ASE output with near-diffraction-limited spatial quality, with M(2)<1.3 in the horizontal and M(2)<1.2 in the vertical, at an ~38% optical-to-optical conversion efficiency. PMID:17603611

Smith, G; Shardlow, P C; Damzen, M J

2007-07-01

158

Analysis of self-amplified spontaneous emission free-electron laser using Lienard-Wiechert fields  

NASA Astrophysics Data System (ADS)

Dynamical equations of electrons in an electron beam with finite length under the influence of a planar wiggler magnetic field and the Lienard-Wiechert fields of other electrons are derived and solved numerically. The analysis is applicable to self-amplified spontaneous emission free-electron laser for which no initial seed radiation is required. By assuming a monoenergetic and filamentary electron beam, thermal effects are neglected and electrons are injected with zero average transverse distance from the wiggler axis. The formalism is based on the retardation effects; therefore, slippage is naturally embedded in the analysis. It was found that energy, number density, and two-particle correlation for the electron beam are modulated by the radiation wavelength which indicates bunching. Spatial, temporal, and angular characteristics of electromagnetic radiation power are also studied.

Kia, M. R.; Maraghechi, B.

2012-04-01

159

Enhancing mammalian hearing by a balancing between spontaneous otoacoustic emissions and spatial coupling  

NASA Astrophysics Data System (ADS)

Nonlinear dynamics has provided significant insights into the origin of frequency discrimination and signal amplification underlying mammalian hearing. Existing signal amplification models, however, tend to ignore two basic known aspects of the hearing: spontaneous otoacoustic emissions (SOAEs) and intrinsic dynamical coupling in the cochlea. We construct and study a class of coupled-oscillator models to remedy this deficiency. Our analysis and computations reveal that the interplay and balance between the two aspects can naturally explain the phenomena of frequency discrimination and signal amplification and, more strikingly, the origin of hearing loss, all at a quantitative level. In the presence of SOAEs, there exists a critical coupling threshold below which hearing loss can occur, suggesting enhancement of coupling as a potentially effective therapeutic strategy to restore or even significantly enhance hearing.

Liu, Zonghua; Li, Baowen; Lai, Ying-Cheng

2012-04-01

160

Ultra-broadband amplified spontaneous emission source by using heterogeneous optical amplifier  

NASA Astrophysics Data System (ADS)

In this work, we propose and experimentally investigate an ultra-broadband amplified spontaneous emission (ASE) light source with 113.8 nm bandwidth (1446.2 to 1560.0 nm) by using a cascaded two-stage optical amplifier, which is consisted of semiconductor optical amplifier (SOA, 1st stage) and erbiumdoped fiber amplifier (EDFA, 2nd stage), when the output intensity is above -35 dBm/0.01 nm. And, the EDFA only uses a 3 m long erbium-doped fiber (EDF) with a 27 mW pumping power and SOA is driven at 200 mA bias current. Moreover, the proposed amplifier also can provide a broadband gain amplification of 114 nm in the wavelengths of 1464.0 and 1578.0 nm with the noise figure distribution of 6.8 to 8.1 dB.

Yeh, C. H.; Chow, C. W.; Chen, J. H.; Lu, S. S.

2012-11-01

161

Systematic study of spontaneous emission in a two-dimensional arbitrary inhomogeneous environment  

SciTech Connect

The spontaneous emission (SE) of the excited atoms in a two-dimensional (2D) arbitrary inhomogeneous environment has been systematically studied. The local density of states, which determines the radiation dynamics of a point source (for 3D) or a line source (for 2D), in particular, the SE rate, is represented by the electric dyadic Green's function. The numerical solution of the electric Green's tensor has been accurately obtained with the finite-difference frequency-domain method with the proper approximations of the monopole and dipole sources. The SE of atoms in photonic crystal and plasmonic metal plates has been comprehensively and comparatively investigated. For both the photonic crystal and plasmonic plates systems, the SEs depend on their respective dispersion relations and could be modified by the finite-structure or finite-size effects. This work is important for SE engineering and the optimized design of optoelectronic devices.

Qiao Pengfei; Sha, Wei E. I.; Choy, Wallace C. H.; Chew, Weng Cho [Department of Electrical and Electronic Engineering, University of Hong Kong, Pokfulam Road (Hong Kong); Department of Electrical and Electronic Engineering, University of Hong Kong, Pokfulam Road (Hong Kong) and Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urban, Illinois 61820 (United States)

2011-04-15

162

Gravity Wave Emission by Spontaneous Imbalance of Baroclinic Waves in the Continuously Stratified Rotating Annulus  

NASA Astrophysics Data System (ADS)

We use a numerical model of the classic differentially heated rotating annulus experiment to study the spontaneous emission of gravity waves (GWs) from jet stream imbalances, which is a major source of these waves in the atmosphere for which no satisfactory parameterization exists. Atmospheric observations are the main tool for the testing and verification of theoretical concepts but have their limitations. Given their specific potential for yielding reproducible data and for studying process dependence on external system parameters, laboratory experiments are an invaluable complementary tool. Experiments with a rotating annulus exhibiting a jet modulated by large-scale waves due to baroclinic instability have already been used to study GWs: Williams et al (2008) observed spontaneously emitted interfacial GWs in a two-layer flow, and Jacoby et al (2011) detected GWs emitted from boundary-layer instabilities in a differentially heated rotating annulus. Employing a finite-volume code for the numerical simulation of a continuously stratified liquid in a differentially heated rotating annulus, we here investigate the GWs in a wide and shallow annulus with relatively large temperature difference between inner and outer cylinder walls. In this atmosphere-like regime where the Brunt-Vaisala frequency is larger than the inertial frequency, various analyses suggest a distinct gravity wave activity. To identify regions of GW emission we decompose the flow into the geostrophic and ageostrophic part through the inversion of the quasi-geostrophic potential vorticity (e.g. Verkley, 2009). The analysis of the geostrophic sources of the ageostrophic flow indicates that, in addition to boundary layer instabilities, spontaneous imbalance in the jet region acts as an important source mechanism. Jacoby, T. N. L., Read, P. L., Williams, P. D. and Young, R. M. B., 2011: Generation of inertia-gravity waves in the rotating thermal annulus by a localised boundary layer instability. Geophys. Astrophys. Fluid Dyn., 105, 161-181. Doi:10.1080/03091929.2011.560151 Verkley, W.T.M., 2009: A balanced approximation of the one-layer shallow-water equations on a sphere. J. Atmos. Sci., 66, 1735-1748. Doi:10.1175/2008JAS2837.1 Williams, P. D., Haine, T. W. N. and Read, P. L., 2008: Inertia-gravity waves emitted from balanced flow: observations, properties, and consequences. J. Atmos. Sci., 65, 3543-3556. Doi:10.1175/2008JAS2480.1

Borchert, Sebastian; Achatz, Ulrich; Rieper, Felix; Fruman, Mark

2013-04-01

163

Towards the two-dimensional imaging of spontaneous ultra-weak photon emission from microbial, plant and animal cells.  

PubMed

Two-dimensional imaging of spontaneous ultra-weak photon emission was measured in the yeast cells, Arabidopsis plant and the human hand using highly sensitive charge coupled device (CCD) camera. For the first time, the detail analysis of measuring parameters such as accumulation time and binning is provided with the aim to achieve two-dimensional images of spontaneous ultra-weak photon emission of good quality. We present data showing that using a hardware binning with binning factor 4 × 4, the accumulation time decreases in the following order: yeast cells (30?min) > the human hand (20?min) > Arabidopsis plant (10?min). Analysis of measuring parameters provides a detailed description of standard condition to be used for two-dimensional spontaneous ultra-weak photon imaging in microbes, plants and animals. Thus, CCD imaging can be employed as a unique tool to examine the oxidative state of the living organism with the application in microbiological, plant and medical research. PMID:23386970

Prasad, Ankush; Pospíšil, Pavel

2013-01-01

164

Towards the two-dimensional imaging of spontaneous ultra-weak photon emission from microbial, plant and animal cells  

PubMed Central

Two-dimensional imaging of spontaneous ultra-weak photon emission was measured in the yeast cells, Arabidopsis plant and the human hand using highly sensitive charge coupled device (CCD) camera. For the first time, the detail analysis of measuring parameters such as accumulation time and binning is provided with the aim to achieve two-dimensional images of spontaneous ultra-weak photon emission of good quality. We present data showing that using a hardware binning with binning factor 4 × 4, the accumulation time decreases in the following order: yeast cells (30?min) > the human hand (20?min) > Arabidopsis plant (10?min). Analysis of measuring parameters provides a detailed description of standard condition to be used for two-dimensional spontaneous ultra-weak photon imaging in microbes, plants and animals. Thus, CCD imaging can be employed as a unique tool to examine the oxidative state of the living organism with the application in microbiological, plant and medical research. PMID:23386970

Prasad, Ankush; Pospisil, Pavel

2013-01-01

165

New Experimental Method of Investigation the Rare Nuclear Transformations Accompanying Atomic Processes:. Bremsstrahlung Emission in Spontaneous Fission of 252Cf  

NASA Astrophysics Data System (ADS)

High energy bremsstrahlung emission during spontaneous fission of 252Cf is observed. The new experimental method to detect rare coincident events by digital storage oscilloscope is used. The ?-rays with energies up to 60 MeV have been measured (by a BGO detector) in coincidence with neutrons detected by a plastic scintillator. The determination of ?-ray emission probability up to the value of about 8 × 10-9event/(MeV × fission) at E?= 60 MeV is achieved.

Eremin, N. V.; Paskhalov, A. A.; Markochev, S. S.; Tsvetkov, E. A.; Mandaglio, G.; Manganaro, M.; Fazio, G.; Giardina, G.; Romaniuk, M. V.

166

Two-photon induced amplified spontaneous emission from needlelike triphenylamine-containing derivative crystals with low threshold  

Microsoft Academic Search

Two-photon induced amplified spontaneous emission (ASE) characteristics of a needlelike crystal were studied. Under two-photon excitation, the upconverted light emission was confined within the crystal and self-waveguided along the needle axis then radiated from the needle tips. The full width at half maximum of the two-photon excited fluorescence reaches 6.5 nm and ASE threshold is as low as 0.29 mJ

Qi-Dai Chen; Hong-Hua Fang; Bin Xu; Jie Yang; Hong Xia; Fei-Peng Chen; Wen-Jing Tian; Hong-Bo Sun

2009-01-01

167

EFFECTS OF INSTILLED EMISSION PARTICULATE MATTER ON ELECTROCARDIOGRAPHIC INDICES AND HEART RATE VARIABILITY (HRV) IN SPONTANEOUSLY HYPERTENSIVE RATS  

EPA Science Inventory

EFFECTS OF INSTILLED EMISSION PARTICULATE MATTER (EPM) ON ELECTROCARDIOGRAPHIC INDICES AND HEART RATE VARIABILITY (HRV) IN SPONTANEOUSLY HYPERTENSIVE (SH) RATS. L.B. Wichers1, J.P. Nolan2, W.H. Rowan2, M.J. Campen3, T.P. Jenkins4, D.L. Costa2, and W.P. Watkinson2. 1UNC SPH, Chap...

168

Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line  

Microsoft Academic Search

Exponential growth of self-amplified spontaneous emission at 530nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

N. D. Arnold; J. Attig; G. Banks; R. Bechtold; K. Beczek; C. Benson; S. Berg; W. Berg; S. G Biedron; J. A Biggs; M. Borland; K. Boerste; M. Bosek; W. R Brzowski; J. Budz; J. A Carwardine; P. Castro; Y.-C Chae; S. Christensen; C. Clark; M. Conde; E. A Crosbie; G. A Decker; R. J Dejus; H. DeLeon; P. K Den Hartog; B. N Deriy; D. Dohan; P. Dombrowski; D. Donkers; C. L Doose; R. J Dortwegt; G. A Edwards; Y. Eidelman; M. J Erdmann; J. Error; R. Ferry; J. Forrestal; H. Freund; H. Friedsam; J. Gagliano; W. Gai; J. N Galayda; R. Gerig; R. L Gilmore; E. Gluskin; G. A Goeppner; J. Goetzen; C. Gold; A. J Gorski; A. E Grelick; M. W Hahne; S. Hanuska; K. C Harkay; G. Harris; A. L Hillman; R. Hogrefe; J. Hoyt; Z. Huang; J. M Jagger; W. G Jansma; M. Jaski; S. J Jones; R. T Keane; A. L Kelly; C. Keyser; K.-J Kim; S. H Kim; M. Kirshenbaum; J. H Klick; K. Knoerzer; R. J Koldenhoven; M. Knott; S. Labuda; R. Laird; J. Lang; F. Lenkszus; E. S Lessner; J. W Lewellen; Y. Li; R. M Lill; A. H Lumpkin; O. A Makarov; G. M Markovich; M. McDowell; W. P McDowell; P. E McNamara; T. Meier; D. Meyer; W. Michalek; S. V. Milton; H. Moe; E. R Moog; L. Morrison; A. Nassiri; J. R Noonan; R. Otto; J. Pace; S. J Pasky; J. M Penicka; A. F Pietryla; G. Pile; C. Pitts; J. Power; T. Powers; C. C. Putnam; A. J Puttkammer; D. Reigle; L. Reigle; D. Ronzhin; E. R Rotela; E. F Russell; V. Sajaev; S. Sarkar; J. C Scapino; K. Schroeder; R. A Seglem; N. S Sereno; S. K Sharma; J. F Sidarous; O. Singh; T. L Smith; R. Soliday; G. A Sprau; S. J Stein; B. Stejskal; V. Svirtun; L. C Teng; E. Theres; K. Thompson; B. J Tieman; J. A Torres; E. M Trakhtenberg; G. Travish; G. F Trento; J. Vacca; I. B Vasserman; N. A Vinokurov; D. R Walters; J. Wang; X. J Wang; J. Warren; S. Wesling; D. L Weyer; G. Wiemerslage; K. Wilhelmi; R. Wright; D. Wyncott; S. Xu; B.-X. Yang; W. Yoder; R. B Zabel

2001-01-01

169

Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line  

NASA Astrophysics Data System (ADS)

Exponential growth of self-amplified spontaneous emission at 530 nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

Arnold, N. D.; Attig, J.; Banks, G.; Bechtold, R.; Beczek, K.; Benson, C.; Berg, S.; Berg, W.; Biedron, S. G.; Biggs, J. A.; Borland, M.; Boerste, K.; Bosek, M.; Brzowski, W. R.; Budz, J.; Carwardine, J. A.; Castro, P.; Chae, Y.-C.; Christensen, S.; Clark, C.; Conde, M.; Crosbie, E. A.; Decker, G. A.; Dejus, R. J.; DeLeon, H.; Den Hartog, P. K.; Deriy, B. N.; Dohan, D.; Dombrowski, P.; Donkers, D.; Doose, C. L.; Dortwegt, R. J.; Edwards, G. A.; Eidelman, Y.; Erdmann, M. J.; Error, J.; Ferry, R.; Flood, R.; Forrestal, J.; Freund, H.; Friedsam, H.; Gagliano, J.; Gai, W.; Galayda, J. N.; Gerig, R.; Gilmore, R. L.; Gluskin, E.; Goeppner, G. A.; Goetzen, J.; Gold, C.; Gorski, A. J.; Grelick, A. E.; Hahne, M. W.; Hanuska, S.; Harkay, K. C.; Harris, G.; Hillman, A. L.; Hogrefe, R.; Hoyt, J.; Huang, Z.; Jagger, J. M.; Jansma, W. G.; Jaski, M.; Jones, S. J.; Keane, R. T.; Kelly, A. L.; Keyser, C.; Kim, K.-J.; Kim, S. H.; Kirshenbaum, M.; Klick, J. H.; Knoerzer, K.; Koldenhoven, R. J.; Knott, M.; Labuda, S.; Laird, R.; Lang, J.; Lenkszus, F.; Lessner, E. S.; Lewellen, J. W.; Li, Y.; Lill, R. M.; Lumpkin, A. H.; Makarov, O. A.; Markovich, G. M.; McDowell, M.; McDowell, W. P.; McNamara, P. E.; Meier, T.; Meyer, D.; Michalek, W.; Milton, S. V.; Moe, H.; Moog, E. R.; Morrison, L.; Nassiri, A.; Noonan, J. R.; Otto, R.; Pace, J.; Pasky, S. J.; Penicka, J. M.; Pietryla, A. F.; Pile, G.; Pitts, C.; Power, J.; Powers, T.; Putnam, C. C.; Puttkammer, A. J.; Reigle, D.; Reigle, L.; Ronzhin, D.; Rotela, E. R.; Russell, E. F.; Sajaev, V.; Sarkar, S.; Scapino, J. C.; Schroeder, K.; Seglem, R. A.; Sereno, N. S.; Sharma, S. K.; Sidarous, J. F.; Singh, O.; Smith, T. L.; Soliday, R.; Sprau, G. A.; Stein, S. J.; Stejskal, B.; Svirtun, V.; Teng, L. C.; Theres, E.; Thompson, K.; Tieman, B. J.; Torres, J. A.; Trakhtenberg, E. M.; Travish, G.; Trento, G. F.; Vacca, J.; Vasserman, I. B.; Vinokurov, N. A.; Walters, D. R.; Wang, J.; Wang, X. J.; Warren, J.; Wesling, S.; Weyer, D. L.; Wiemerslage, G.; Wilhelmi, K.; Wright, R.; Wyncott, D.; Xu, S.; Yang, B.-X.; Yoder, W.; Zabel, R. B.

2001-12-01

170

Spontaneous-Emission Rate in Microcavities: Application to Two-Dimensional Photonic Crystals C. Shen, K. Michielsen, and H. De Raedt*  

E-print Network

Spontaneous-Emission Rate in Microcavities: Application to Two-Dimensional Photonic Crystals C or suppression of the spontaneous-emission rate by photonic crystals. DOI: 10.1103/PhysRevLett.96.120401 PACS crystals (PhCs) [15­17]. It was suggested that PhCs with a complete photonic band gap (PBG) allow complete

171

CONTROL OF COPPER SMELTER FUGITIVE EMISSIONS  

EPA Science Inventory

This report deals with fugitive emissions from copper smelting and with related emission control measures. The study involved evaluation of the controls now used in the copper smelting industry and development of suggestions for alternative control devices and practices. A brief ...

172

Spontaneous emission inhibition of telecom-band quantum disks inside single nanowire on different substrates  

E-print Network

We investigate the inhibited spontaneous emission of telecom-band InAs quantum disks (Qdisks) in InP nanowires (NWs). We have evaluated how the inhibition is affected by different disk diameter and thickness. We also compared the inhibition in standing InP NWs and those NWs laying on silica (SiO2), and silicon (Si) substrates. We found that the inhibition is altered when we put the NW on the high-refractive index materials of Si. Experimentally, the inhibition factor $\\zeta$ of the Qdisk emission at 1,500 nm decreases from 4.6 to 2.5 for NW on SiO2 and Si substrates, respectively. Those inhibitions are even much smaller than that of 6.4 of the standing NW. The inhibition factors well agree with those calculated from the coupling of the Qdisk to the fundamental guided mode and the continuum of radiative modes. Our observation can be useful for the integration of the NW as light sources in the photonic nanodevices.

M. D. Birowosuto; G. Zhang; A. Yokoo; M. Takiguchi; M. Notomi

2014-05-30

173

Spontaneous emission inhibition of telecom-band quantum disks inside single nanowire on different substrates  

E-print Network

We investigate the inhibited spontaneous emission of telecom-band InAs quantum disks (Qdisks) in InP nanowires (NWs). We have evaluated how the inhibition is affected by different disk diameter and thickness. We also compared the inhibition in standing InP NWs and those NWs laying on silica (SiO2), and silicon (Si) substrates. We found that the inhibition is altered when we put the NW on the high-refractive index materials of Si. Experimentally, the inhibition factor $\\zeta$ of the Qdisk emission at 1,500 nm decreases from 4.6 to 2.5 for NW on SiO2 and Si substrates, respectively. Those inhibitions are even much smaller than that of 6.4 of the standing NW. The inhibition factors well agree with those calculated from the coupling of the Qdisk to the fundamental guided mode and the continuum of radiative modes. Our observation can be useful for the integration of the NW as light sources in the photonic nanodevices.

Birowosuto, M D; Yokoo, A; Takiguchi, M; Notomi, M

2014-01-01

174

Asbestos Emissions from Baghouse Controlled Sources  

Microsoft Academic Search

There is virtually no information published on the absolute efficiency of baghouses in reducing the emissions of fine particles of asbestos. This lack of information is unfortunate because serious occupational health problems may result from the common practice of recirculating air to conserve energy. Emission testing has been conducted at five asbestos processing plants where the emissions are controlled by

COLIN F. HARWOOD; DAVID K. OESTREICH; PAUL SIEBERT; JOHN D. STOCKHAM

1975-01-01

175

Gravity Wave Emission by Spontaneous Imbalance of Baroclinic Waves in the Continuously Stratified Rotating Annulus  

NASA Astrophysics Data System (ADS)

We use a numerical model of the classic differentially heated rotating annulus experiment to study the spontaneous emission of gravity waves (GWs) from jet stream imbalances, which is a major source of these waves in the atmosphere for which no satisfactory parameterization exists. Atmospheric observations are the main tool for the testing and verification of theoretical concepts but have their limitations. Given their specific potential for yielding reproducible data and for studying process dependence on external system parameters, laboratory experiments are an invaluable complementary tool. Experiments with a rotating annulus exhibiting a jet modulated by large-scale waves due to baroclinic instability have already been used to study GWs: Williams et al (2008) observed spontaneously emitted interfacial GWs in a two-layer flow, and Jacoby et al (2011) detected GWs emitted from boundary-layer instabilities in a differentially heated rotating annulus. Employing a new finite-volume code for the numerical simulation of a continuously stratified liquid in a differentially heated rotating annulus, we here investigate whether such an experiment might be useful for studies of spontaneous imbalance. A major problem was the identification of experimental parameters yielding an atmosphere-like regime where the Brunt-Vaisala frequency is larger than the inertial frequency, so that energy transport by the lowest-frequency waves is predominantly horizontal while high-frequency GWs transport energy vertically. We show that this is indeed the case for a wide and shallow annulus with relatively large temperature difference between the inner and outer cylinder walls. We also show that this set-up yields a conspicuous signal in the horizontal divergence field close to the meandering jet. Various analyses support the notion that this signal is predominantly due to GWs superposed on a geostrophic flow. Jacoby, T. N. L., Read, P. L., Williams, P. D. and Young, R. M. B., 2011: Generation of inertia-gravity waves in the rotating thermal annulus by a localised boundary layer instability. Geophys. Astrophys. Fluid Dyn., 105, 161-181. doi:10.1080/03091929.2011.560151 Williams, P. D., Haine, T. W. N. and Read, P. L., 2008: Inertia-gravity waves emitted from balanced flow: observations, properties, and consequences. J. Atmos. Sci., 65, 3543-3556. doi:10.1175/2008JAS2480.1

Borchert, S.; Achatz, U.; Rieper, F.; Fruman, M. D.

2012-04-01

176

Coke pushing emission control system  

SciTech Connect

A method is described for controlling coke oven emissions comprising the steps of: (A) aligning a one-spot, open-top coke quenching car with the coke oven, (B) providing a coke guide from the coke oven to the car, (C) positioning a fume hood over the car, with the fume hood having a length about equal to the length of the car, (D) pushing hot coke from the coke oven through the coke guide and into the car, (E) withdrawing gases from the fume hood during step (D) and passing said gases to gas cleaning equipment at a gas flowrate of between about 1000 and about 3500 scfmd per ton of coke pushed under step (D), and (F) substantially upon completion of step (E) moving the car from under the fume hood to a quenching station with the hot coke in the car exposed to the atmosphere and without further withdrawal of gases from the hot coke to the gas cleaning equipment.

Kwasnoski, D.; Symons, C.

1980-07-08

177

Brain modularity controls the critical behavior of spontaneous activity  

PubMed Central

The human brain exhibits a complex structure made of scale-free highly connected modules loosely interconnected by weaker links to form a small-world network. These features appear in healthy patients whereas neurological diseases often modify this structure. An important open question concerns the role of brain modularity in sustaining the critical behaviour of spontaneous activity. Here we analyse the neuronal activity of a model, successful in reproducing on non-modular networks the scaling behaviour observed in experimental data, on a modular network implementing the main statistical features measured in human brain. We show that on a modular network, regardless the strength of the synaptic connections or the modular size and number, activity is never fully scale-free. Neuronal avalanches can invade different modules which results in an activity depression, hindering further avalanche propagation. Critical behaviour is solely recovered if inter-module connections are added, modifying the modular into a more random structure. PMID:24621482

Russo, R.; Herrmann, H. J.; de Arcangelis, L.

2014-01-01

178

Loss of the tectorial membrane protein CEACAM16 enhances spontaneous, stimulus-frequency, and transiently evoked otoacoustic emissions.  

PubMed

?-Tectorin (TECTA), ?-tectorin (TECTB), and carcinoembryonic antigen-related cell adhesion molecule 16 (CEACAM) are secreted glycoproteins that are present in the tectorial membrane (TM), an extracellular structure overlying the hearing organ of the inner ear, the organ of Corti. Previous studies have shown that TECTA and TECTB are both required for formation of the striated-sheet matrix within which collagen fibrils of the TM are imbedded and that CEACAM16 interacts with TECTA. To learn more about the structural and functional significance of CEACAM16, we created a Ceacam16-null mutant mouse. In the absence of CEACAM16, TECTB levels are reduced, a clearly defined striated-sheet matrix does not develop, and Hensen's stripe, a prominent feature in the basal two-thirds of the TM in WT mice, is absent. CEACAM16 is also shown to interact with TECTB, indicating that it may stabilize interactions between TECTA and TECTB. Although brain-stem evoked responses and distortion product otoacoustic emissions are, for most frequencies, normal in young mice lacking CEACAM16, stimulus-frequency and transiently evoked emissions are larger. We also observed spontaneous otoacoustic emissions (SOAEs) in 70% of the homozygous mice. This incidence is remarkable considering that <3% of WT controls have SOAEs. The predominance of SOAEs >15 kHz correlates with the loss of Hensen's stripe. Results from mice lacking CEACAM16 are consistent with the idea that the organ of Corti evolved to maximize the gain of the cochlear amplifier while preventing large oscillations. Changes in TM structure appear to influence the balance between energy generation and dissipation such that the system becomes unstable. PMID:25080593

Cheatham, Mary Ann; Goodyear, Richard J; Homma, Kazuaki; Legan, P Kevin; Korchagina, Julia; Naskar, Souvik; Siegel, Jonathan H; Dallos, Peter; Zheng, Jing; Richardson, Guy P

2014-07-30

179

Realization of dynamic thermal emission control  

NASA Astrophysics Data System (ADS)

Thermal emission in the infrared range is important in various fields of research, including chemistry, medicine and atmospheric science. Recently, the possibility of controlling thermal emission based on wavelength-scale optical structures has been intensively investigated with a view towards a new generation of thermal emission devices. However, all demonstrations so far have involved the ‘static’ control of thermal emission; high-speed modulation of thermal emission has proved difficult to achieve because the intensity of thermal emission from an object is usually determined by its temperature, and the frequency of temperature modulation is limited to 10–100 Hz even when the thermal mass of the object is small. Here, we experimentally demonstrate the dynamic control of thermal emission via the control of emissivity (absorptivity), at a speed four orders of magnitude faster than is possible using the conventional temperature-modulation method. Our approach is based on the dynamic control of intersubband absorption in n-type quantum wells, which is enhanced by an optical resonant mode in a photonic crystal slab. The extraction of electrical carriers from the quantum wells leads to an immediate change in emissivity from 0.74 to 0.24 at the resonant wavelength while maintaining much lower emissivity at all other wavelengths.

Inoue, Takuya; Zoysa, Menaka De; Asano, Takashi; Noda, Susumu

2014-10-01

180

Effects of spontaneous, assisted, and controlled ventilatory modes in halothane-anesthetized geldings.  

PubMed

Cardiopulmonary effects of spontaneous, assisted, and controlled ventilatory modes were determined with 6 young, healthy geldings anesthetized with halothane at a constant dose (1.3 minimum alveolar concentration). All horses were in lateral recumbency, and all modes of ventilation were studied at least once during each anesthetic exposure. Cardiac output did not differ between spontaneous and assisted ventilation modes, but both modes were associated with significantly (P less than 0.05) higher cardiac output than that with controlled ventilation. The PaCO2 differed significantly (P less than 0.01) between all modes of ventilation. Although controlled ventilation maintained a normal PaCO2, assisted ventilation reduced PaCO2 as compared with spontaneous ventilation with less cardiovascular depression than that with controlled ventilation. Mixed venous O2 tensions were higher with spontaneous and assisted ventilation modes than with controlled ventilation. Except for shorter inspiratory time and smaller inspiratory/expiratory ratio associated with spontaneous ventilation, there were no ventilatory mode-related effects on ventilatory variables. PMID:3717746

Hodgson, D S; Steffey, E P; Grandy, J L; Woliner, M J

1986-05-01

181

Asbestos Emission Control Plan Dakota County, Minnesota  

E-print Network

Asbestos Emission Control Plan UMore Park Dakota County, Minnesota Prepared for University of Minnesota Revised: July 22, 2009 UMP005460 #12;Asbestos Emission Control Plan UMore Park Dakota County park environmental\\WorkFiles\\Phase II Investigation WO#1 and #6\\Phase II Work Plan\\Asbestos ECP\\ECP_V2

Netoff, Theoden

182

Effects of contralateral acoustic stimulation on spontaneous otoacoustic emissions and hearing threshold fine structure.  

PubMed

Medial olivocochlear (MOC) influence on cochlear mechanics can be noninvasively, albeit indirectly, explored via the effects of contralateral acoustic stimulation (CAS) on otoacoustic emissions. CAS-mediated effects are particularly pronounced for spontaneous otoacoustic emissions (SOAEs), which are typically reduced in amplitude and shifted upward in frequency by CAS. We investigated whether similar frequency shifts and magnitude reductions were observed behaviorally in the fine structure of pure-tone hearing thresholds, a phenomenon thought to share a common underlying mechanism with SOAEs. In normal-hearing listeners, fine-resolution thresholds were obtained over a narrow frequency range centered on the frequency of an SOAE, both in the absence and presence of 60-dB SPL broadband CAS. While CAS shifted threshold fine structure patterns and SOAEs upward in frequency by a comparable amount, little reduction in the presence or depth of fine structure was observed at frequencies near those of SOAEs. In fact, CAS typically improved thresholds, particularly at threshold minima, and increased fine structure depth when reductions in the amplitude of the associated SOAE were less than 10 dB. Additional measurements made at frequencies distant from SOAEs, or near SOAEs that were more dramatically reduced in amplitude by the CAS, revealed that CAS tended to elevate thresholds and reduce threshold fine structure depth. The results suggest that threshold fine structure is sensitive to MOC-mediated changes in cochlear gain, but that SOAEs complicate the interpretation of threshold measurements at nearby frequencies, perhaps due to masking or other interference effects. Both threshold fine structure and SOAEs may be significant sources of intersubject and intrasubject variability in psychoacoustic investigations of MOC function. PMID:25245498

Dewey, James B; Lee, Jungmee; Dhar, Sumitrajit

2014-12-01

183

Nonequilibrium quantum fluctuations of a dispersive medium: Spontaneous emission, photon statistics, entropy generation, and stochastic motion  

NASA Astrophysics Data System (ADS)

We study the implications of quantum fluctuations of a dispersive medium, under steady rotation, either in or out of thermal equilibrium with its environment. A rotating object exhibits a quantum instability by dissipating its mechanical motion via spontaneous emission of photons, as well as internal heat generation. Universal relations are derived for the radiated energy and angular momentum as trace formulas involving the object's scattering matrix. We also compute the quantum noise by deriving the full statistics of the radiated photons out of thermal and/or dynamic equilibrium. The (entanglement) entropy generation is quantified and the total entropy is shown to be always increasing. Furthermore, we derive a Fokker-Planck equation governing the stochastic angular motion resulting from the fluctuating backreaction frictional torque. As a result, we find a quantum limit on the uncertainty of the object's angular velocity in steady rotation. Finally, we show in some detail that a rotating object drags nearby objects, making them spin parallel to its axis of rotation. A scalar toy model is introduced to simplify the technicalities and ease the conceptual complexities and then a detailed discussion of quantum electrodynamics is presented.

Maghrebi, Mohammad F.; Jaffe, Robert L.; Kardar, Mehran

2014-07-01

184

Near infrared amplified spontaneous emission in a dye-doped polymeric waveguide for active plasmonic applications.  

PubMed

Near-infrared amplified spontaneous emission (ASE) from an optically-pumped dye-doped polymeric slab waveguide, consisting of IR-140 in PMMA on a glass substrate, has been characterised. The ASE gain was measured using the variable stripe length method. Linewidth narrowing with increasing pump intensity was observed, indicating ASE gain in this material. The effects of the dye concentration and pump intensity on the gain were investigated under linear operation. The maximum achieved gain coefficient is ? ~68 cm(-1) for a film with 0.8 wt % of IR-140 to PMMA for a pump intensity of 43.4 mJ/cm(2). The polarisation dependence of the ASE gain was also investigated by measuring the gain coefficient of orthogonal TE and TM modes and varying the pump polarisation relative to the amplifier length. It was observed that there is some degree of gain anisotropy when the pump polarisation is aligned perpendicular to the length, but that the gain was isotropic when the pump polarisation is aligned parallel the length. The applicability of IR-140 doped PMMA for active plasmonic applications is discussed. PMID:24921362

Keshmarzi, Elham Karami; Tait, R Niall; Berini, Pierre

2014-05-19

185

Theoretical study of amplified spontaneous emission using a model based on a geometrically dependent gain coefficient  

NASA Astrophysics Data System (ADS)

It is shown that a model based on a geometrically dependent gain coefficient (GDGC), which is characterized by gain parameters (m?, {\\gamma }_{L}^{\\max }, b), introduces a powerful method to describe amplified spontaneous emission (ASE) intensity behavior and its bandwidth reduction when the ASE is propagating along the z-direction. The model also gives correct predictions for unsaturated and saturated gain coefficients and the frequency dependence of the ASE output intensity in a given laser system. For the calculation, the GDGC model in saturated and unsaturated conditions along with the intensity rate equation were applied, and for verification of the model the reported ASE intensity measurements and the measured bandwidth reduction in KrF lasers were utilized. The present model will have applications in any type of pulsed laser system of different active media and different dimensions without going through complicated analysis or utilizing heavy computer numerical computations. Details of the present approach will be given and the excellent agreement with the available and typical experimental measurements for KrF lasers confirms the validity of the proposed GDGC model.

Hariri, A.; Sarikhani, S.

2013-08-01

186

Wavelength swept amplified spontaneous emission source for high speed retinal optical coherence tomography at 1060 nm.  

PubMed

The wavelength swept amplified spontaneous emission (ASE) source presented in this paper is an alternative approach to realize a light source for high speed swept source optical coherence tomography (OCT). ASE alternately passes a cascade of different optical gain elements and tunable optical bandpass filters. In this work we show for the first time a wavelength swept ASE source in the 1060 nm wavelength range, enabling high speed retinal OCT imaging. We demonstrate ultra-rapid retinal OCT at a line rate of 170 kHz, a record sweep rate at 1060 nm of 340 kHz with 70 nm full sweep width, enabling an axial resolution of 11 ?m. Two different implementations of the source are characterized and compared to each other. The last gain element is either a semiconductor optical amplifier or an Ytterbium-doped fibre amplifier enabling high average output power of >40 mW. Various biophotonic imaging examples provide a wide range of quality benchmarks achievable with such sources. PMID:21780301

Eigenwillig, Christoph M; Klein, Thomas; Wieser, Wolfgang; Biedermann, Benjamin R; Huber, Robert

2011-08-01

187

Effects of low-frequency biasing on spontaneous otoacoustic emissions: amplitude modulation.  

PubMed

The dynamic effects of low-frequency biasing on spontaneous otoacoustic emissions (SOAEs) were studied in human subjects under various signal conditions. Results showed a combined suppression and modulation of the SOAE amplitudes at high bias tone levels. Ear-canal acoustic spectra demonstrated a reduction in SOAE amplitude and growths of sidebands while increasing the bias tone level. These effects varied depending on the relative strength of the bias tone to a particular SOAE. The SOAE magnitudes were suppressed when the cochlear partition was biased in both directions. This quasi-static modulation pattern showed a shape consistent with the first derivative of a sigmoid-shaped nonlinear function. In the time domain, the SOAE amplitudes were modulated with the instantaneous phase of the bias tone. For each biasing cycle, the SOAE envelope showed two peaks each corresponded to a zero crossing of the bias tone. The temporal modulation patterns varied systematically with the level and frequency of the bias tone. These dynamic behaviors of the SOAEs are consistent with the shifting of the operating point along the nonlinear transducer function of the cochlea. The results suggest that the nonlinearity in cochlear hair cell transduction may be involved in the generation of SOAEs. PMID:18247892

Bian, Lin; Watts, Kelly L

2008-02-01

188

Nonequilibrium quantum fluctuations of a dispersive medium: Spontaneous emission, photon statistics, entropy generation, and stochastic motion  

E-print Network

We study the implications of quantum fluctuations of a dispersive medium, under steady rotation, either in or out of thermal equilibrium with its environment. A rotating object exhibits a quantum instability by dissipating its mechanical motion via spontaneous emission of photons, as well as internal heat generation. Universal relations are derived for the radiated energy and angular momentum as trace formulas involving the object's scattering matrix. We also compute the quantum noise by deriving the full statistics of the radiated photons out of thermal and/or dynamic equilibrium. The (entanglement) entropy generation is quantified, and the total entropy is shown to be always increasing. Furthermore, we derive a Fokker-Planck equation governing the stochastic angular motion resulting from the fluctuating back-reaction frictional torque. As a result, we find a quantum limit on the uncertainty of the object's angular velocity in steady rotation. Finally, we show in some detail that a rotating object drags nearby objects, making them spin parallel to its axis of rotation. A scalar toy model is introduced in the first part to simplify the technicalities and ease the conceptual complexities; a detailed discussion of quantum electrodynamics is presented in the second part.

Mohammad F. Maghrebi; Robert L. Jaffe; Mehran Kardar

2014-01-03

189

Spontaneous emission of a photon: wave packet structures and atom-photon entanglement  

E-print Network

Spontaneous emission of a photon by an atom is described theoretically in three dimensions with the initial wave function of a finite-mass atom taken in the form of a finite-size wave packet. Recoil and wave-packet spreading are taken into account. The total atom-photon wave function is found in the momentum and coordinate representations as the solution of an initial-value problem. The atom-photon entanglement arising in such a process is shown to be closely related to the structure of atom and photon wave packets which can be measured in the coincidence and single-particle schemes of measurements. Two predicted effects, arising under the conditions of high entanglement, are anomalous narrowing of the coincidence wave packets and, under different conditions, anomalous broadening of the single-particle wave packets. Fundamental symmetry relations between the photon and atom single-particle and coincidence wave packet widths are established. The relationship with the famous scenario of Einstein-Podolsky-Rosen is discussed.

M. V. Fedorov; M. A. Efremov; A. E. Kazakov; K. W. Chan; C. K. Law; J. H. Eberly

2004-12-14

190

Measurements of amplified spontaneous emission in ?-conjugated polymer films with different morphology  

NASA Astrophysics Data System (ADS)

?-conjugated polymers (PCPs) are attractive candidates as gain media in laser applications due to their high photoluminescence quantum efficiency in broad spectral range. However, the self-absorption of long-lived excited states was considered to be a limitation for achieving more effective organic lasers. Moreover, the morphology of films is found to be crucial to their optical and electrical properties recently. In this work, we studied amplified spontaneous emission (ASE) of a typical PCP, namely, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) films with a 10 ns 532 nm pulse laser focused by a cylindrical lens for obtaining an excitation area in the form of a 100 ?m wide and 1 cm long stripe. In an as cast MEH-PPV film, the thresholds increase with the temperatures increase due to the thermal torsion and vibration mode shorten the conjugation chain. On the other hand, a MEH-PPV film which is annealed in Nitrogen at 350 K of half hour, the ASE is not observed at both 300 K and 77 K, for annealing will form ?- stacks which increase the interchain interaction. Further analysis suggests that interchain excimers instead of intrachain excitons may be more primary to optical properties in annealed MEH-PPV film. Our measurements suggest that the morphology of the film instead of long lived photoexcitation with lifetime sensitive to the temperature is more crucial to threshold of ASE, as well as, to PCPs lasers.

Wang, Yuchen; Yang, Xiao; Wang, Ruizhi; Sheng, Chuanxiang

2014-09-01

191

Controlling air emissions from incinerators  

SciTech Connect

Last year, EPA published final rules establishing technical standards for the use and disposal of wastewater biosolids (40 CFR, Part 503). Subpart E specifically regulates the operations of and emissions from municipal wastewater biosolids incinerators.

Foisy, M.B.; Li, R.; Chattapadhyay, A. [Malcolm Pirnie, Inc., White Plains, NY (United States)] [and others

1994-04-01

192

Examination of bleederless ventilation practices for spontaneous combustion control in US coal mines  

SciTech Connect

The U.S. Bureau of Mines examined bleederless ventilation practices to evaluate their use as a spontaneous combustion control measure in U.S. coal mines. Results indicate that restricting airflow into mined-out areas (bleederless ventilation) is recognized worldwide as a spontaneous combustion control measure. However, ventilation practices commonly used to limit airflow to mined-out areas are not easily applicable to United States mining conditions, systems, experience and regulations. The types of bleederless ventilation systems used throughout the world and the spontaneous combustion risks associated with these systems are discussed. Primary design considerations for bleederless ventilation consist of the interaction of ventilation practices, methane drainage, ground control, seal construction and mine monitoring. Technological improvements needed for U.S. application of bleederless ventilation are also discussed.

Organiscak, J.A.; Smith, A.C.; Diamond, W.P.; Mucho, T.P. [Bureau of Mines, Pittsburgh, PA (United States)

1995-12-31

193

Calculation of spontaneous emission from a V-type three-level atom in photonic crystals using fractional calculus  

SciTech Connect

Fractional time derivative, an abstract mathematical operator of fractional calculus, is used to describe the real optical system of a V-type three-level atom embedded in a photonic crystal. A fractional kinetic equation governing the dynamics of the spontaneous emission from this optical system is obtained as a fractional Langevin equation. Solving this fractional kinetic equation by fractional calculus leads to the analytical solutions expressed in terms of fractional exponential functions. The accuracy of the obtained solutions is verified through reducing the system into the special cases whose results are consistent with the experimental observation. With accurate physical results and avoiding the complex integration for solving this optical system, we propose fractional calculus with fractional time derivative as a better mathematical method to study spontaneous emission dynamics from the optical system with non-Markovian dynamics.

Huang, Chih-Hsien; Hsieh, Wen-Feng [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, 1001 Tahsueh Rd., Hsinchu 300, Taiwan (China); Institute of Electro-Optical Science and Engineering, National Cheng Kung University, 1 Dahsueh Rd., Tainan 701, Taiwan (China); Wu, Jing-Nuo; Cheng, Szu-Cheng [Department of Physics, Chinese Culture University, Yangming Mt., Taipei 111, Taiwan (China); Li, Yen-Yin [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, 1001 Tahsueh Rd., Hsinchu 300, Taiwan (China)

2011-07-15

194

First Observation of Self-Amplified Spontaneous Emission in a Free-Electron Laser at 109 nm Wavelength  

Microsoft Academic Search

We present the first observation of self-amplified spontaneous emission (SASE) in a free-electron laser (FEL) in the vacuum ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron laser gain (approximately 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width, and intensity fluctuations, are all consistent with the present models for SASE FELs.

J. Andruszkow; B. Aune; V. Ayvazyan; N. Baboi; R. Bakker; V. Balakin; D. Barni; A. Bazhan; M. Bernard; A. Bosotti; J. C. Bourdon; W. Brefeld; R. Brinkmann; S. Buhler; J.-P. Carneiro; M. Castellano; P. Castro; L. Catani; S. Chel; Y. Cho; S. Choroba; E. R. Colby; W. Decking; P. den Hartog; M. Desmons; M. Dohlus; D. Edwards; H. T. Edwards; B. Faatz; J. Feldhaus; M. Ferrario; M. J. Fitch; K. Flöttmann; M. Fouaidy; A. Gamp; T. Garvey; C. Gerth; M. Geitz; E. Gluskin; V. Gretchko; U. Hahn; W. H. Hartung; D. Hubert; M. Hüning; R. Ischebek; M. Jablonka; J. M. Joly; M. Juillard; T. Junquera; P. Jurkiewicz; A. Kabel; J. Kahl; H. Kaiser; T. Kamps; V. V. Katelev; J. L. Kirchgessner; M. Körfer; L. Kravchuk; G. Kreps; J. Krzywinski; T. Lokajczyk; R. Lange; B. Leblond; M. Leenen; J. Lesrel; M. Liepe; A. Liero; T. Limberg; R. Lorenz; Lu Hui Hua; Lu Fu Hai; C. Magne; M. Maslov; G. Materlik; A. Matheisen; J. Menzel; P. Michelato; W.-D. Möller; A. Mosnier; U.-C. Müller; O. Napoly; A. Novokhatski; M. Omeich; H. S. Padamsee; C. Pagani; F. Peters; B. Petersen; P. Pierini; J. Pflüger; P. Piot; B. Phung Ngoc; L. Plucinski; D. Proch; K. Rehlich; S. Reiche; D. Reschke; I. Reyzl; J. Rosenzweig; J. Rossbach; S. Roth; E. L. Saldin; W. Sandner; Z. Sanok; H. Schlarb; G. Schmidt; P. Schmüser; J. R. Schneider; E. A. Schneidmiller; H.-J. Schreiber; S. Schreiber; P. Schütt; J. Sekutowicz; L. Serafini; D. Sertore; S. Setzer; S. Simrock; B. Sonntag; B. Sparr; F. Stephan; V. A. Sytchev; S. Tazzari; F. Tazzioli; M. Tigner; M. Timm; M. Tonutti; E. Trakhtenberg; R. Treusch; D. Trines; V. Verzilov; T. Vielitz; V. Vogel; G. V. Walter; R. Wanzenberg; T. Weiland; H. Weise; J. Weisend; M. Wendt; M. Werner; M. M. White; I. Will; S. Wolff; M. V. Yurkov; K. Zapfe; P. Zhogolev; F. Zhou

2000-01-01

195

Self-amplified spontaneous emission saturation at the Advanced Photon Source free-electron laser (abstract) (invited)  

Microsoft Academic Search

Today, many bright photon beams in the ultraviolet and x-ray wavelength range are produced by insertion devices installed in specially designed third-generation storage rings. There is the possibility of producing photon beams that are orders of magnitude brighter than presently achieved at synchrotron sources, by using self-amplified spontaneous emission (SASE). At the Advanced Photon Source (APS), the low-energy undulator test

E. R. Moog; S. V. Milton; N. D. Arnold; C. Benson; W. Berg; S. G. Biedron; M. Borland; Y.-C. Chae; R. J. Dejus; P. K. den Hartog; B. Deriy; M. Erdmann; E. Gluskin; Z. Huang; K.-J. Kim; J. W. Lewellen; Y. Li; A. H. Lumpkin; O. Makarov; A. Nassiri; V. Sajaev; R. Soliday; B. J. Tieman; E. M. Trakhtenberg; G. Travish; I. B. Vasserman; N. A. Vinokurov; G. Wiemerslage; B. X. Yang

2002-01-01

196

Fabrication and amplified spontaneous emission of Eu(DBM) 3 Phen doped step-index polymer optical fiber  

Microsoft Academic Search

A step-index polymer optical fiber (SI POF) with a core of poly(methyl methacrylate) (PMMA) containing Eu(DBM)3Phen has been fabricated by a preform technique. Fluorescence analysis showed that there is not obvious change in the local environment around Eu3+with the increase of Eu(DBM)3Phen doping concentration. Amplified spontaneous emission (ASE) phenomenon of the doped SI POF by end-pumping with an Ar+-laser of

Hao Liang; Zhiqiang Zheng; Zengchang Li; Jie Xu; Biao Chen; Hui Zhao; Qijin Zhang; Hai Ming

2004-01-01

197

Electrical Generation of Spontaneous Optical Emission in Electrically Modulated Two-Dimensional Electron Gases at Low-Temperatures  

Microsoft Academic Search

A detailed theoretical study is presented for spontaneous optical emission from a two-dimensional electron gas (2DEG) in the presence of a unidirectional spatially periodic modulation at low temperatures. The momentum- and energy-balance equations for electron-photon interactions in the device system are solved self-consistently using the Boltzmann equation, from which we can obtain the frequency and the intensity of the electromagnetic

W. Xu; C. Zhang

1998-01-01

198

Effortful control and spontaneous regulation of emotional behavior in children  

E-print Network

linear regression revealed a significant relationship between Effortful Control scores and Emotional Regulation after receiving an undesirable gift. Furthermore, this relationship was stronger when only the tasks involving suppressing/initiating motor...

Kieras, Jessica E

2013-02-22

199

Diesel engine emissions: A timing control approach  

Microsoft Academic Search

Growing demands are being placed on the diesel engine industry to lower emission levels. A key ingredient in emissions reduction is precise injection pump to engine timing control. This paper outlines a unique approach to dynamically time an injection pump to an engine during its initial test cycle while developing the ability to repeat the timing function using the same

P. T. Henderson; D. Wells; M. Haddox

1987-01-01

200

Triple amplified spontaneous emissions from a conjugated copolymer BEHP-co-MEH-PPV in solution  

NASA Astrophysics Data System (ADS)

The spectral and laser properties of conjugated polymer {[2-[2?,5?-bis(2?-ethylhexyloxy)phenyl]-1,4-phenylenevinylene]-co-[2-methoxy-5-(2?-ethylhexyloxy)-1,4-phenylenevinylene]} (BEHP-co-MEH-PPV) in benzene had been studied and presented in this paper. BEHP-co-MEH-PPV was dissolved in benzene to form solutions of concentrations ranging from 1 mM to 10 mM. The absorption spectra had shown no new band when concentration increased; this indicates no dimer formation in these solutions for all concentrations mentioned above. The fluorescence spectra for the concentration 2.5 mM have shown two peaks at 560 nm and 600 nm, which could be attributed to monomer and excimer of MEH-PPV alone. At higher concentration (5 mM) the band at 560 nm almost disappeared and the band at 600 nm became dominant. At still higher concentration, the longer wavelength side of these spectra, there was a hump at 650 nm. So, this new band around 650 nm could be due to double excimer of MEH-PPV alone. When the laser pump power at 355 nm and concentration of above solution were suitably chosen, we observed amplified spontaneous emission (ASE) at 570 nm, 605 nm and 650 nm. These ASE peaks could arise from the monomer, excimer and double excimer states of MEH-PPV as a segment. To the best of our knowledge this is perhaps the first report on ASE from double excimer of the conjugated copolymer, BEHP-co-MEH-PPV, in liquid solution.

Ibnaouf, K. H.; Prasad, Saradh; Masilamani, V.; AlSalhi, M. S.; Mustapha, N.; Alyamani, A.

2013-09-01

201

Motor vehicle fuel vapor emission control assembly  

SciTech Connect

This patent describes a motor vehicle fuel vapor emission control assembly. It comprises fuel vapor emission control means and structural vehicle support means integral with the motor vehicle for providing structural support for the motor vehicle, the fuel vapor emission control means being for controlling emissions of fuel vapor from the motor vehicle. It comprises adsorption means for releasably adsorbing fuel vapors from a fuel reservoir of the vehicle; housing means for containing such adsorption means, the housing means being positioned within a hollow in a structural member of the structural vehicle support means; and vapor communication means for communicating fuel vapor from the reservoir to the adsorption means within the housing means and for communicating fuel vapor from within the housing means to a fuel burning engine of the vehicle.

Oslapas, A.G.

1991-10-29

202

Variable emissivity laser thermal control system  

DOEpatents

A laser thermal control system for a metal vapor laser maintains the wall mperature of the laser at a desired level by changing the effective emissivity of the water cooling jacket. This capability increases the overall efficiency of the laser.

Milner, Joseph R. (Livermore, CA)

1994-01-01

203

Spontaneous Centralization of Control in a Network of Company Ownerships  

PubMed Central

We introduce a model for the adaptive evolution of a network of company ownerships. In a recent work it has been shown that the empirical global network of corporate control is marked by a central, tightly connected “core” made of a small number of large companies which control a significant part of the global economy. Here we show how a simple, adaptive “rich get richer” dynamics can account for this characteristic, which incorporates the increased buying power of more influential companies, and in turn results in even higher control. We conclude that this kind of centralized structure can emerge without it being an explicit goal of these companies, or as a result of a well-organized strategy. PMID:24324594

Krause, Sebastian M.; Peixoto, Tiago P.; Bornholdt, Stefan

2013-01-01

204

Spontaneous centralization of control in a network of company ownerships  

E-print Network

We introduce a model for the adaptive evolution of a network of company ownerships. In a recent work it has been shown that the empirical global network of corporate control is marked by a central, tightly connected "core" made of a small number of large companies which control a significant part of the global economy. Here we show how a simple, adaptive "rich get richer" dynamics can account for this characteristic, which incorporates the increased buying power of more influential companies, and in turn results in even higher control. We conclude that this kind of centralized structure can emerge without it being an explicit goal of these companies, or as a result of a well-organized strategy.

Krause, Sebastian M; Bornholdt, Stefan

2013-01-01

205

Spontaneous centralization of control in a network of company ownerships.  

PubMed

We introduce a model for the adaptive evolution of a network of company ownerships. In a recent work it has been shown that the empirical global network of corporate control is marked by a central, tightly connected "core" made of a small number of large companies which control a significant part of the global economy. Here we show how a simple, adaptive "rich get richer" dynamics can account for this characteristic, which incorporates the increased buying power of more influential companies, and in turn results in even higher control. We conclude that this kind of centralized structure can emerge without it being an explicit goal of these companies, or as a result of a well-organized strategy. PMID:24324594

Krause, Sebastian M; Peixoto, Tiago P; Bornholdt, Stefan

2013-01-01

206

Spontaneous autoresuscitation in a model of respiratory control.  

PubMed

We introduce a closed-loop model of respiratory control incorporating a conductance-based central pattern generator (CPG), low-pass filtering of CPG output by the respiratory musculature, gas exchange in the lung, metabolic oxygen demand, and chemosensation. The CPG incorporates Butera, Rinzel and Smith (BRS)'s (1999) conditional pacemaker model. BRS model cells can support quiescent, bursting, or beating activity depending on the level of excitatory drive; we identify these activity modes with apnea (cessation of breathing), eupnea (normal breathing), and tachypnea (excessively rapid breathing). We demonstrate the coexistence of two dynamically stable behaviors in the closed-loop model, corresponding respectively to eupnea and tachypnea. The latter state represents a novel failure mode within a respiratory control model. In addition, the closed-loop system exhibits a form of autoresuscitation: conductances intrinsic to the BRS model buffer the CPG against brief episodes of hypoxia, steering the system away from catastrophic collapse as can occur with tachypnea. PMID:23367459

Diekman, Casey O; Wilson, Christopher G; Thomas, Peter J

2012-01-01

207

Comment on “Competition between coherent emission and broadband spontaneous emission in the quantum free electron laser” [Phys. Plasmas 20, 033106 (2013)  

SciTech Connect

We point out that in the equation for the electron distribution evolution during Thomson/Compton or undulator radiation used in the paper: “Competition between coherent emission and broadband spontaneous emission in the quantum free electron laser” by G. R. M. Robb and R. Bonifacio [Phys. Plasmas 20, 033106 (2013)], the weight function should be the distribution of the number of emitted photons and not the photon energy distribution. Nevertheless, the considerations expressed in this comment do not alter the conclusions drawn in the paper in object.

Petrillo, V.; Rossi, A. R.; Serafini, L. [Università di Milano-INFN, Via Celoria, 16 Milano (Italy)] [Università di Milano-INFN, Via Celoria, 16 Milano (Italy)

2013-12-15

208

Ongoing Spontaneous Activity Controls Access to Consciousness: A Neuronal Model for Inattentional Blindness  

PubMed Central

Even in the absence of sensory inputs, cortical and thalamic neurons can show structured patterns of ongoing spontaneous activity, whose origins and functional significance are not well understood. We use computer simulations to explore the conditions under which spontaneous activity emerges from a simplified model of multiple interconnected thalamocortical columns linked by long-range, top-down excitatory axons, and to examine its interactions with stimulus-induced activation. Simulations help characterize two main states of activity. First, spontaneous gamma-band oscillations emerge at a precise threshold controlled by ascending neuromodulator systems. Second, within a spontaneously active network, we observe the sudden “ignition” of one out of many possible coherent states of high-level activity amidst cortical neurons with long-distance projections. During such an ignited state, spontaneous activity can block external sensory processing. We relate those properties to experimental observations on the neural bases of endogenous states of consciousness, and particularly the blocking of access to consciousness that occurs in the psychophysical phenomenon of “inattentional blindness,” in which normal subjects intensely engaged in mental activity fail to notice salient but irrelevant sensory stimuli. Although highly simplified, the generic properties of a minimal network may help clarify some of the basic cerebral phenomena underlying the autonomy of consciousness. PMID:15819609

2005-01-01

209

Surface plasmon enhanced spontaneous emission rate of InGaN/GaN quantum wells probed by time-resolved photoluminescence spectroscopy  

E-print Network

-organic chemical vapor deposi- tion MOCVD . The grown structures consist of a GaN 4 m buffer layer, an InGaN SQW 3Surface plasmon enhanced spontaneous emission rate of InGaN/GaN quantum wells probed by time online 8 August 2005 We observed a 32-fold increase in the spontaneous emission rate of InGaN/GaN quantum

Okamoto, Koichi

210

Io control of Jovian radio emission  

NASA Technical Reports Server (NTRS)

The possibility of Io controlling Jovian decametric radio emission, particularly in the region below 22 MHz, is discussed. Results of a two-year survey at 26.3 at 26.3 MHz are presented which demonstrate the control of Io over a high-intensity storm component of the radio emission and the independence of a weak radio component from the phase of Io, as was observed at lower frequencies. It is thus hypothesized that Io control is a flux-dependent rather than a frequency-dependent phenomenon, and results of analyses at 18 and 10 MHz which support this hypothesis are presented. The apparent correlation between frequency and Io control is thus shown to result from a selection effect due to the increase of non-Io emission with decreasing frequency and relative antenna detection threshold. This result implies a contiguous Io-controlled source region extending out several Jovian radii along the Io flux tube.

Desch, M. D.

1980-01-01

211

Control of Jovian Radio Emission by Callisto  

NASA Technical Reports Server (NTRS)

Galileo has been in orbit around Jupiter since December 1995 and a large database has been collected. We present the results of a survey of the plasma wave data for the frequency range 2.0 MHz to 5.6 MHz, the low frequency decametric (DAM) emissions. While the control of a portion of the radio emission by the moon lo is well known, and Ganymede control has been more recently indicated, we report that a small but significant portion of DAM emission is seen to be correlated with the orbital phase of Callisto. While the occurrence rate of emission controlled by Ganymede and Callisto is considerably less than for lo, the power levels can be nearly the same. We estimate the power of the Callisto-dependent emission to be approx. 70% of the Io-dependent radio emission and about the same as the Ganymede-dependent radio emission. This result indicates an Alfven current system associated with Callisto, and thus a significant interaction of the magnetosphere of Callisto with that of Jupiter as is believed to exist for both lo and Ganymede.

Menietti, J. D.; Gurnett, D. A.; Christopher, I.

2001-01-01

212

Economic growth and carbon emission control  

NASA Astrophysics Data System (ADS)

The question about whether environmental improvement is compatible with continued economic growth remains unclear and requires further study in a specific context. This study intends to provide insight on the potential for carbon emissions control in the absence of international agreement, and connect the empirical analysis with theoretical framework. The Chinese electricity generation sector is used as a case study to demonstrate the problem. Both social planner and private problems are examined to derive the conditions that define the optimal level of production and pollution. The private problem will be demonstrated under the emission regulation using an emission tax, an input tax and an abatement subsidy respectively. The social optimal emission flow is imposed into the private problem. To provide tractable analytical results, a Cobb-Douglas type production function is used to describe the joint production process of the desired output and undesired output (i.e., electricity and emissions). A modified Hamiltonian approach is employed to solve the system and the steady state solutions are examined for policy implications. The theoretical analysis suggests that the ratio of emissions to desired output (refer to 'emission factor'), is a function of productive capital and other parameters. The finding of non-constant emission factor shows that reducing emissions without further cutting back the production of desired outputs is feasible under some circumstances. Rather than an ad hoc specification, the optimal conditions derived from our theoretical framework are used to examine the relationship between desired output and emission level. Data comes from the China Statistical Yearbook and China Electric Power Yearbook and provincial information of electricity generation for the year of 1993-2003 are used to estimate the Cobb-Douglas type joint production by the full information maximum likelihood (FIML) method. The empirical analysis shed light on the optimal policies of emissions control required for achieving the social goal in a private context. The results suggest that the efficiency of abatement technology is crucial for the timing of executing the emission tax. And emission tax is preferred to an input tax, as long as the detection of emissions is not costly and abatement technology is efficient. Keywords: Economic growth, Carbon emission, Power generation, Joint production, China

Zhang, Zhenyu

213

Ternary particle emission in spontaneous fission of 250Cf and 252Cf and in neutron induced fission of 249Cf and 251Cf  

NASA Astrophysics Data System (ADS)

The emission probabilities and the energy distributions of tritons, ? and 6He particles emitted in the spontaneous ternary fission (zero excitation energy) of 250Cf and 252Cf and in the cold neutron induced fission (excitation energy ?6.5 MeV) of 249Cf and 251Cf are determined. The particle identification was done with suited ?E-E telescope detectors, at the IRMM (Geel, Belgium) for the spontaneous fission and at the ILL (Grenoble, France) for the neutron induced fission measurements. Hence particle emission characteristics of the fissioning systems 250Cf and 252Cf are obtained at zero and at about 6.5 MeV excitation energies. While the triton emission probability is hardly influenced by the excitation energy, the 4He and 6He emission probability in spontaneous fission is higher than for neutron induced fission. This can be explained by the strong influence of the cluster preformation probability on the ternary particle emission probability.

Vermote, S.; Wagemans, C.; Serot, O.; Heyse, J.; Van Gils, J.; Soldner, T.; Geltenbort, P.; AlMahamid, I.; Tian, G.; Rao, L.

2010-06-01

214

Polarized spontaneous emission from blue-green m-plane GaN-based light emitting diodes  

NASA Astrophysics Data System (ADS)

The polarization of spontaneous emission was investigated for various indium compositions and quantum wells on m-plane oriented gallium nitride (GaN) light emitting diodes (LEDs) grown on bulk-GaN substrates. Internal light scattering and depolarization was mitigated with application of absorber materials to the LED die. The polarization ratio (?) was measured under electrical injection for devices with InGaN active regions emitting up to 520 nm and observed as high as 96%. Values of ? were independent of drive current. The valence band energy separation (?E) was characterized using spectral measurement and temperature dependent optical analysis of valence band hole distributions.

Brinkley, Stuart E.; Lin, You-Da; Chakraborty, Arpan; Pfaff, Nathan; Cohen, Daniel; Speck, James S.; Nakamura, Shuji; DenBaars, Steven P.

2011-01-01

215

Geometry effect on spontaneous emission decay in nanosized Y2O3-Eu3+ particles  

NASA Astrophysics Data System (ADS)

A strong influence of shape and size on spontaneous luminescence of Eu atoms has been observed in a new class of Y2O3-Eu3+ nanoparticles including nanospheres, nanopowder and nanoplates. We demonstrate a possibility of engineering recombination time ? in nano-objects by changing the local optical environment.

Zaitsev, S. V.; Yermolayeva, Yu. V.; Gruzintsev, A. N.; Kudrenko, E. A.; Zverkova, I. I.; Bezkrovnyi, O.; Tolmachev, A. V.; Emelchenko, G. A.

2014-11-01

216

Significant Suppression of Spontaneous Emission in SiO2 Photonic Crystals Made with Tb3+-Doped LaF3 Nanoparticles  

E-print Network

made with LaF3:Tb3+ nanoparticles were fabricated. The spontaneous emission lifetime of the 5D4 f 7F4 of photoluminescent guests, such as fluorescent dyes and quantum dots. The emission band of fluorescent dyes is often observed for fluorescent dye molecules, are not observed. The bandwidth of a

Brolo, Alexandre G.

217

Improvement of amplified spontaneous emission by encapsulating green fluorescent dye in inverted-opal titania photonic crystals.  

PubMed

Amplified spontaneous emission (ASE) characteristics of a green fluorescent dye (10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1] benzo- pyrano [6,7,8-ij]quinolizin-11-one) (C545T) encapsulated in a highly ordered three-dimensional (3D) inverted-opal titania (TiO(2)) photonic crystal (PC) microcavity were studied. Due to the utilization of a TiO(2) PC, the emission spectrum was greatly narrowed and the ASE threshold, gain, and loss were significantly improved. The threshold, gain, and loss reached 1.25 mJ pulse(-1) cm(-2), 34.69 cm(-1), and 16.9 cm(-1), respectively. The possible reason for the improvement in the ASE performance by the PC is attributed to the 3D photon localization by the microcavity effect of the PC. PMID:18709061

Zhang, Dingke; Wang, Yanping; Cao, Yanling; Ma, Dongge

2008-03-20

218

Amplified spontaneous emission from 2,7-bis(4-pyridyl)fluorene-doped DNA-cetyltrimethyl ammonium complex films  

NASA Astrophysics Data System (ADS)

The 2,7-bis(4-pyridyl)fluorene (BPF) was synthesized via a Suzuki coupling reaction. The optical spectra properties of BPF and BPF-deoxyribonucleic acid (DNA)-cetyltrimethyl ammonium (CTMA) thin films composed of BPF, DNA, and CTMA were characterized by the measurements of UV/Vis absorption spectra and fluorescence spectra. The amplified spontaneous emission (ASE) of the BPF-DNA-CTMA films was researched experimentally by pumping of a pulse laser with a wavelength of 355 nm. The results show that the absorption peak and the fluorescence peak of BPF are located at 327 and 380 nm, respectively. The emission peak of BPF corresponds to the vibronic transitions from an excited state of S1 level to the ground state of S0 level. The ASE peak of the BPF-DNA-CTMA film is located at 384 nm, and the threshold of ASE excited energy density is 3.12 mJ.cm-2.

Zhao, Xiuhua; Li, Xing; Zhao, Yayun; Zhang, Jie; Pan, Jianguo; Zhou, Jun

2013-10-01

219

FIRED HEATERS: NITROGEN OXIDES EMISSIONS AND CONTROLS  

EPA Science Inventory

The report gives results of a study of nitrogen oxide (NOx) emissions from, and controls for, fired heaters. The petroleum refining and chemical manufacturing industries account for most of fired-heater energy use with an estimated 4600 fired heaters in operation, in these two in...

220

WASTE INCINERATION AND EMISSION CONTROL TECHNOLOGIES  

EPA Science Inventory

The paper gives results of a survey of available waste incineration and emission control technologies in the U.S., Japan, and Western Europe. Increasing concern over landfills as a waste management option and the decreasing availability of sites have focused attention on incinera...

221

CONTROLLING ODOROUS EMISSIONS FROM IRON FOUNDRIES  

EPA Science Inventory

The report discusses the control of odorous emissions from iron foundries. he main process sources of odors in iron foundries are mold and core making, casting, and sand shakeout. he odors are usually caused by chemicals, which may be present as binders and other additives to the...

222

Relation between reaction time and the phase of spontaneous and controlled breathing patterns.  

PubMed

In this study simple reaction time (simple RT) to a visual stimulus of a single subject was measured during spontaneous and controlled breathing, in which the duration of expiration was prolonged (Asian technique). The phases of breathing were classified as the pause between expiration and inspiration, the inspiration phase, the transition from inspiration to expiration, and the expiration phase. Analysis of data from about 6000 trials indicated that RT to the stimulus was shortest during the transition from inspiration to expiration in controlled breathing. PMID:8570348

Kobashi, N; Sugiyama, Y

1995-10-01

223

Laser induced amplified spontaneous emission from the f 0g+ (3P0) ion-pair state of I2  

NASA Astrophysics Data System (ADS)

Laser induced amplified spontaneous emission (ASE) from the f 0g+ (3P0) (vf = 1-7) ion-pair state of I2 was directly observed using an optical-optical double resonance technique with the B 0u+ (vB = 21) valence state as the intermediate state. The emission detected at ~1660 nm was assigned to transitions from the f 0g+ state to the D 0u+ (3P2) ion-pair state. The transitions observed in the dispersed IR emission spectra were found to be between vibrational levels having the same vibrational quantum numbers in both electronic states, vf = vD. This is due to the almost parallel nature of the potential energy functions of the f 0g+ and D 0u+ states, leading to almost unit values for the Franck-Condon factors for vf = vD. That the observed infrared emission is due to ASE is shown by the facts that it propagated in a limited range of solid angles, exhibited a clear threshold against the input-laser power, and had different polarization to that of laser induced fluorescence.

Hoshino, Shoma; Araki, Mitsunori; Furukawa, Hiroki; Ross, Stephen C.; Tsukiyama, Koichi

2013-03-01

224

Imaging of Ultraweak Spontaneous Photon Emission from Human Body Displaying Diurnal Rhythm  

Microsoft Academic Search

The human body literally glimmers. The intensity of the light emitted by the body is 1000 times lower than the sensitivity of our naked eyes. Ultraweak photon emission is known as the energy released as light through the changes in energy metabolism. We successfully imaged the diurnal change of this ultraweak photon emission with an improved highly sensitive imaging system

Masaki Kobayashi; Daisuke Kikuchi; Hitoshi Okamura; Joseph Najbauer

2009-01-01

225

Low threshold amplified spontaneous emission from tin oxide quantum dots: a instantiation of dipole transition silence semiconductors  

NASA Astrophysics Data System (ADS)

Direct bandgap semiconductors, such as In2O3, Cu2O, and SnO2, have enormous applications in photochemistry, photovoltaics, and optoelectronics. Due to the same parity of conduction and valence bands, the dipole transition is silent in these direct bandgap semiconductors. The low band-to-band transition efficiency prevents them from high intensity light emission or absorption. Here, we report the fabrication of SnO2 quantum dots (QDs) with sizes less than the exciton Bohr radius by a facile ``top-down'' strategy based on laser fragmentation of SnO in water. The SnO2 QDs shows exciton emission at ~300 nm with a high quantum yield of ~17%. Amplified spontaneous exciton emission is also achieved from a thin layer of SnO2 QDs dispersed in PEG400 on a quartz substrate. Therefore, we have shown that SnO2 QDs can be a potential luminescent material suitable for the realization of ultraviolet B lasing devices.Direct bandgap semiconductors, such as In2O3, Cu2O, and SnO2, have enormous applications in photochemistry, photovoltaics, and optoelectronics. Due to the same parity of conduction and valence bands, the dipole transition is silent in these direct bandgap semiconductors. The low band-to-band transition efficiency prevents them from high intensity light emission or absorption. Here, we report the fabrication of SnO2 quantum dots (QDs) with sizes less than the exciton Bohr radius by a facile ``top-down'' strategy based on laser fragmentation of SnO in water. The SnO2 QDs shows exciton emission at ~300 nm with a high quantum yield of ~17%. Amplified spontaneous exciton emission is also achieved from a thin layer of SnO2 QDs dispersed in PEG400 on a quartz substrate. Therefore, we have shown that SnO2 QDs can be a potential luminescent material suitable for the realization of ultraviolet B lasing devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03523a

Pan, Shu Sheng; Yu, Siu Fung; Zhang, Wen Fei; Zhu, Hai; Lu, Wei; Jin, Li Min

2013-11-01

226

Full characterization of the amplified spontaneous emission from a diode-pumped high-power laser system.  

PubMed

We present the first complete temporal and spatial characterization of the amplified spontaneous emission (ASE) of laser radiation generated by a diode-pumped high-power laser system. The ASE of the different amplifiers was measured independently from the main pulse and was characterized within a time window of -10ms ? t ? 10ms and an accuracy of up to 15fs around the main pulse. Furthermore, the focusability and the energy of the ASE from each amplifier was measured after recompression. Using our analysis method, the laser components, which need to be optimized for a further improvement of the laser contrast, can be identified. This will be essential for laser-matter interaction experiments requiring a minimized ASE intensity or fluence. PMID:24921820

Keppler, S; Hornung, M; Bödefeld, R; Sävert, A; Liebetrau, H; Hein, J; Kaluza, M C

2014-05-01

227

Amplified spontaneous emission measurement of a line-narrowed, tunable, Ti:Al2O3 amplifier using rubidium absorption  

NASA Technical Reports Server (NTRS)

Amplified spontaneous emission, ASE, generated by a Ti:Al2O3 laser amplifier has been measured as a function of pump energy, and thus gain, using the atomic absorption of rubidium, Rb, gas at 0.780 micron. By tuning the Ti:Al2O3 laser, the Rb cell could selectively absorb the narrow spectral bandwidth laser radiation while transmitting the wide spectral bandwidth ASE. Transmission of laser amplifier pulses through a Rb absorption cell, measured at various temperatures, thus allows the measurement of the weak ASE in the vicinity of the strong laser pulse. A model for the transmission of Rb as a function of temperature and wavelength has been developed. The measured transmissions are in good agreement with the transmission model predictions.

Barnes, James C.; Barnes, Norman P.; Lockard, George E.; Cross, Patricia L.

1989-01-01

228

Model Identification for Optimal Diesel Emissions Control  

SciTech Connect

In this paper we develop a model based con- troller for diesel emission reduction using system identification methods. Specifically, our method minimizes the downstream readings from a production NOx sensor while injecting a minimal amount of urea upstream. Based on the linear quadratic estimator we derive the closed form solution to a cost function that accounts for the case some of the system inputs are not controllable. Our cost function can also be tuned to trade-off between input usage and output optimization. Our approach performs better than a production controller in simulation. Our NOx conversion efficiency was 92.7% while the production controller achieved 92.4%. For NH3 conversion, our efficiency was 98.7% compared to 88.5% for the production controller.

Stevens, Andrew J.; Sun, Yannan; Song, Xiaobo; Parker, Gordon

2013-06-20

229

Factors controlling dimethylsulfide emission from salt marshes  

NASA Technical Reports Server (NTRS)

The factors that control the emission of methylated gases from salt marshes are being studied. Research focusses on dimethylsulfide (DMS) formation and the mechanism of DMS and CH4 emission to the atmosphere. The approach is to consider the plants as valves regulating the emission of methylated gases to the atmosphere with the goal of developing appropriate methods for emission measurement. In the case of CH4, the sediment is the source and transport to the atmosphere occurs primarily through the internal gas spaces in the plants. The source of DMS appears to be dimethyl sulfoniopropionate (DMSP) which may play a role in osmoregulation in plant tissues. Concentrations of DMSP in leaves are typically several-fold higher than in roots and rhizomes. Even so, the large below ground biomass of this plant means that 2/3 of the DMSP in the ecosystem is below ground on the aerial basis. Upon introduction to sediment water, DMSP rapidly decomposes to DMS and acrylic acid. The solubility of a gas (its equilibrium vapor pressure) is a fundamental aspect of gas exchange kinetics. The first comprehensive study was conducted of DMS solubility in freshwater and seawater. Data suggest that the Setchenow relation holds for H at intermediate salinities collected. These data support the concept that the concentration of DMS in the atmosphere is far from equilibrium with seawater.

Dacey, John W. H.; Wakeham, S. G.; Howes, B. L.

1985-01-01

230

40 CFR 266.104 - Standards to control organic emissions.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Standards to control organic emissions. 266.104 Section 266...Furnaces § 266.104 Standards to control organic emissions. (a) DRE standard ...efficiency (DRE) of 99.99% for all organic hazardous constituents in the...

2011-07-01

231

Spectral broadening effects of spontaneous emission and density of state on plasmonic enhancement in cermet waveguides.  

PubMed

Based on the full integration formula of Purcell factor (PF) deduced from Fermi's Golden Rule, the plasmonic enhancement in Au(1-?)S3N4(?) cermet waveguides is evaluated with the joint impact of finite emission linewidth and the broadening of PF spectrum. The calculation results indicate that the PF would be significantly degraded by the two broadening effects though the SPP resonance frequency can be tuned with different volume fractions (?) of Si3N4. It is also found that the critical emission linewidth is approximately linear to the PF spectrum linewidth. Thus in order to achieve strong plasmonic enhancement, both the emission and PF spectrum linewidths should be dramatically reduced. PMID:23388935

Chen, Keyong; Feng, Xue; Zhang, Chao; Cui, Kaiyu; Huang, Yidong

2013-01-14

232

Asbestos emissions from baghouse controlled sources.  

PubMed

There is virtually no information published on the absolute efficiency of baghouses in reducing the emmisions of fine particles of asbestos. This lack of information is unfortunate because serious occupational health problems may result from the common practice of recirculating air to conserve energy. Emission testing has been conducted at five asbestos processing plants where the emissions are controlled by baghouses. The results showed that the mass removal efficiency frequently exceeded 99.00%. Membrane filter samples of the effluent were examined by optical and electron microscope. It was observed that despite the high mass efficiency, the number of fibers emitted, which were greater than 1.5 mum in length, was about 10(4)-10(5) fibers/m3, while the number of fibers less than 1.5 mum was 10(7)-10(8) fibers/m3. The significance of the size of the fibers in terms of probably health impact is briefly discussed. PMID:1227285

Harwood, C F; Oestreich, D K; Siebert, P; Stockham, J D

1975-08-01

233

Amplified spontaneous emission of Eu(DBM)3Phen doped step-index polymer optical fiber by end-pumping with a YAG  

Microsoft Academic Search

Eu(DBM)3Phen doped poly(methyl methac- rylate) core step-index polymer optical fiber (SI POF) has been fabricated and related properties of the doping mate- rial were discussed. Amplified spontaneous emission (ASE) at 613 nm of a SI POF with 40 cm length has been observed at ambient temperature by end-pumping with a YAG at 355

Hao Liang; Biao Chen; Qijin Zhang; Zhiqiang Zheng; Hai Ming; Fuquan Guo

2005-01-01

234

The research and implementation of coalfield spontaneous combustion of carbon emission WebGIS based on Silverlight and ArcGIS server  

NASA Astrophysics Data System (ADS)

As an important sub-topic of the natural process of carbon emission data public information platform construction, coalfield spontaneous combustion of carbon emission WebGIS system has become an important study object. In connection with data features of coalfield spontaneous combustion carbon emissions (i.e. a wide range of data, which is rich and complex) and the geospatial characteristics, data is divided into attribute data and spatial data. Based on full analysis of the data, completed the detailed design of the Oracle database and stored on the Oracle database. Through Silverlight rich client technology and the expansion of WCF services, achieved the attribute data of web dynamic query, retrieval, statistical, analysis and other functions. For spatial data, we take advantage of ArcGIS Server and Silverlight-based API to invoke GIS server background published map services, GP services, Image services and other services, implemented coalfield spontaneous combustion of remote sensing image data and web map data display, data analysis, thematic map production. The study found that the Silverlight technology, based on rich client and object-oriented framework for WCF service, can efficiently constructed a WebGIS system. And then, combined with ArcGIS Silverlight API to achieve interactive query attribute data and spatial data of coalfield spontaneous emmission, can greatly improve the performance of WebGIS system. At the same time, it provided a strong guarantee for the construction of public information on China's carbon emission data.

Zhu, Z.; Bi, J.; Wang, X.; Zhu, W.

2014-02-01

235

Approximate Entropy Values Demonstrate Impaired Neuromotor Control of Spontaneous Leg Activity in Infants with Myelomeningocele  

PubMed Central

Purpose One obstacle to providing early intervention to infants with myelomeningocele (MMC) is the challenge of quantifying impaired neuromotor control of movements early in life. Methods We used the nonlinear analysis tool Approximate Entropy (ApEn) to analyze periodicity and complexity of supine spontaneous lower extremity movements of infants with MMC and typical development (TD) at 1, 3, 6 and 9 months of age. Results Movements of infants with MMC were more regular and repeatable (lower ApEn values) than movements of infants with TD indicating less adaptive and flexible movement patterns. For both groups ApEn values decreased with age, and the movements of infants with MMC were less complex than movements of infants with TD. Further, for infants with MMC, lesion level and age of walking onset correlated negatively with ApEn values. Conclusions Our study begins to demonstrate the feasibility of ApEn to identify impaired neuromotor control in infants with MMC. PMID:21829116

Smith, Beth A.; Teulier, Caroline; Sansom, Jennifer; Stergiou, Nicholas; Ulrich, Beverly D.

2012-01-01

236

Spontaneous and stimulated emission of ZnO/ZnMgO asymmetric double quantum wells  

NASA Astrophysics Data System (ADS)

ZnO/Zn 0.85Mg 0.15O asymmetric double quantum wells (ADQWs) were fabricated on an m-plane Al 2O 3 substrate by plasma-assisted molecular beam epitaxy (P-MBE). The ADQW structures were confirmed by comparing the photoluminescence (PL) spectra of the ZnO/Zn 0.85Mg 0.15O MQWs and ZnO/Zn 0.85Mg 0.15O ADQWs. The exciton tunnelling properties of the ADQWs were studied by means of temperature-dependent PL spectra. The carrier tunneling through the thin barrier is conducive to stimulated emission in the wide wells (WWs) of the ADQWs. The origin of the stimulated emission is exciton-exciton scattering in the WWs of ADQWs.

Su, S. C.; Lu, Y. M.; Xing, G. Z.; Wu, T.

2010-11-01

237

Coherent optical transition radiation and self-amplified spontaneous emission generated by chicane-compressed electron beams  

SciTech Connect

Observations of strongly enhanced optical transition radiation (OTR) following significant bunch compression of photoinjector beams by a chicane have been reported during the commissioning of the Linac Coherent Light Source (LCLS) accelerator and recently at the Advanced Photon Source (APS) linac. These localized transverse spatial features involve signal enhancements of nearly a factor of 10 and 100 in the APS case at the 150-MeV and 375-MeV OTR stations, respectively. They are consistent with a coherent process seeded by noise and may be evidence of a longitudinal space charge (LSC) microbunching instability which leads to coherent OTR (COTR) emissions. Additionally, we suggest that localized transverse structure in the previous self-amplified spontaneous emission (SASE) free-electron laser (FEL) data at APS in the visible-UV regime as reported at FEL02 may be attributed to such beam structure entering the FEL undulators and inducing the SASE startup at those structures. Separate beam structures 120 microns apart in x and 2.9 nm apart in wavelength were reported. The details of these observations and operational parameters will be presented.

Lumpkin, A.H.; /Fermilab; Dejus, R.J.; Sereno, N.S.; /Argonne

2009-02-01

238

The Impact of IFNL4 rs12979860 Polymorphism on Spontaneous Clearance of Hepatitis C; A Case-Control Study  

PubMed Central

Background: About 30% of individuals with hepatitis C virus (HCV) infection are able to clear HCV spontaneously. Differences in host genetics affect the outcome of HCV infection. Single nucleotide polymorphisms (SNPs) of the Interferon lambda (IFNL) genes were associated with spontaneous and treatment-induced clearance of HCV infection. Objectives: The aim of this study was to evaluate the association between the IFNL4 rs12979860 SNP and spontaneous clearance of HCV infection in Iranian population. Materials and Methods: A case-control study was designed on 91 cases with spontaneous HCV infection clearance and 259 patients with persistent HCV infection as the control group. The rs12979860 SNP was assessed as the most common IFNL polymorphism by PCR-RFLP method. Results: Distribution of rs12979860 CC genotype in the spontaneous clearance group was around two folds of its distribution in chronic hepatitis C group (P < 0.001, OR = 4.09, 95% CI = 2.44-6.86). Conclusions: The rs12979860 SNP was observed as a strong host genetic factor associated with spontaneous clearance of hepatitis C infection. PMID:25419220

Sharafi, Heidar; Alavian, Seyed Moayed; Behnava, Bita; Pouryasin, Ali; Keshvari, Maryam

2014-01-01

239

IDENTIFICATION, ASSESSMENT, AND CONTROL OF FUGITIVE PARTICULATE EMISSIONS  

EPA Science Inventory

The technical manual, designed to assist national, state, and local control agency personnel and industry personnel in evaluating fugitive emission control plans and in developing cost-effective control strategies, describes the identification, assessment, and control of fugitive...

240

Electrostatic control of acid mist emissions  

SciTech Connect

This paper describes a two-phased study of the control of acid mist emissions using a compact, wet electrostatic precipitator (WESP). The goal of the study was to determine the degree of acid mist control that could be achieved when a compact WESP is used to replace or augment the mist eliminators in a flue gas desulfurization (FGD) system. Phase I of the study examined the electrical operation of a lab-scale WESP collecting an acid mist from a coal combustion pilot plant equipped with a spray chamber. The results of this study were used to develop and validate a computer model of the WESP. In Phase II, measurements were made at two utility scrubber installations to determine the loadings of acid mist, fly ash, and scrubber carryover. These measurements were used as input to the model to project the performance of a retrofitted WESP.

Dahlin, R S [Southern Research Inst., Birmingham, AL (United States)] [Southern Research Inst., Birmingham, AL (United States); Brown, T D [USDOE Pittsburgh Energy Technology Center, PA (United States)] [USDOE Pittsburgh Energy Technology Center, PA (United States)

1991-01-01

241

CONTROL OF HYDROCARBON EMISSIONS FROM GASOLINE LOADING BY REFRIGERATION SYSTEMS  

EPA Science Inventory

The report gives results of a study of the capabilities of refrigeration systems, operated at three temperatures, to control volatile organic compound (VOC) emissions from truck loading at bulk gasoline terminals. Achievable VOC emission rates were calculated for refrigeration sy...

242

40 CFR 52.987 - Control of hydrocarbon emissions.  

Code of Federal Regulations, 2013 CFR

...Installation of emission control systems on a 25,000 barrel capacity crude oil storage tank at Cities Service Pipeline Company, Haynesville, Louisiana with a final compliance date of February 1, 1980. This shall result in an estimated hydrocarbon emission...

2013-07-01

243

40 CFR 52.987 - Control of hydrocarbon emissions.  

Code of Federal Regulations, 2012 CFR

...Installation of emission control systems on a 25,000 barrel capacity crude oil storage tank at Cities Service Pipeline Company, Haynesville, Louisiana with a final compliance date of February 1, 1980. This shall result in an estimated hydrocarbon emission...

2012-07-01

244

Spontaneous control of HIV replication, but not HAART-induced viral suppression, is associated with lower activation of immune cells.  

PubMed

HIV replication control is important to reduce AIDS progression. We determined frequency and activation status of immune cells in spontaneous HIV controllers vs. individuals with highly active antiretroviral therapy (HAART)-controlled viral load. HIV controllers exhibited significantly higher frequency of CD4 T cells and myeloid dendritic cells compared with HAART-controlled viral load. Additionally, HIV controllers have a significantly lower percentage of cells expressing activation markers on CD4 and CD8 T cells, myeloid dendritic cells, and natural killer cells. These findings suggest that during HIV infection, conservation of a normal frequency and physiological range of immune activation is associated with spontaneous, but not HAART-induced, control of viral replication. PMID:24732877

Taborda, Natalia A; Rugeles, María T; Montoya, Carlos J

2014-08-01

245

Coke quench car emission control system  

SciTech Connect

A coke quench car emission control system includes a coke car and a filter car connected in tandem for joint movement on rails disposed adjacent a coke oven. A hood and recuperator are mounted on a third car disposed on auxiliary rails which extend longitudinally along the upper portions of both the quench car and the filter car and in end-wise alignment. The hood is adapted to be coupled to the coke oven for receiving coke during a pushing operation. The recuperation has an inlet coupled to the hood for receiving emissions and withdrawing heat therefrom. The recuperator also has an outlet which is disposed adjacent the inlet of a filter system mounted on the filter car, when the third car is positioned atop the quench car. The third car is sized so that it can be moved on the auxiliary rails from a position atop the quench car to a position atop the filter car whereby the quench car can be exposed for a quenching operation.

Baum, J.P.

1983-07-19

246

Chemical mechanisms in mercury emission control technologies  

NASA Astrophysics Data System (ADS)

The emission of elemental mercury in the flue gas from coal-burning power plants is a major environmental concern. Control technologies utilizing activated carbon show promise and are currently under intense review. Oxidation and capture of elemental mercury on activated carbon was extensively investigated in a variety of flue gas atmospheres. Extensive parametric testing with individual and a variety of combinations and concentrations of reactive flue gas components and spectroscopic examination of the sulfur and chlorine forms present before and after breakthrough have led to an improved model to explain the kinetic and capacity results. The improved model delineates the independent Lewis acid oxidation site as well as a zig-zag carbene site on the carbon edge that performs as a Lewis base in reacting with both the oxidized mercury formed at the oxidation site and with the acidic flue gas components in competing reactions to form organochlorine, sulfinate, and sulfate ester moieties on the carbon edge.

Olson, E. S.; Laumb, J. D.; Benson, S. A.; Dunham, G. E.; Sharma, R. K.; Mibeck, B. A.; Miller, S. J.; Holmes, M. J.; Pavlish, J. H.

2003-05-01

247

"Spontaneous"' desorption: A controlled phenomenon for surface analysis application? Part I: New evidence for a sputtering process induced by a well localized field enhanced desorption  

NASA Astrophysics Data System (ADS)

The mechanism of Spontaneous Desorption Mass Spectrometry (SDMS) has been investigated through the use of extraction electrodes with circular aperture, in place of the more conventional grid system. High emission rates of contaminant and sample specific anions have been recorded from reference materials like CsI and phenylalanine. It is shown that the emission rate is controlled by the existence and the characteristics of the aperture edge such as sharpness or (and) rugosity. Geometrical shape and material composition of this well localized region also influence the emission rate and ion yields. Experimentally, the sample emitting zone has been determined in two ways: (1) from the variation of the emission yield of sample specific ions as a function of the deposit diameter and (2) from the lateral distribution of impacts of these ions after their flight path. Both experiments clearly show that this emitting zone (impact zone of the primaries) has a ring shape related to the circular aperture parameters. SIMION ion trajectory simulations and field strength calculations demonstrate that the primary ions are mostly emitted from the well defined edges (inner and outer) of the electrode. The emission rate is shown to decrease rapidly with time after the application of the extraction potential indicating both a degradation of the edge sharpness or microtips density and a decrease of adsorbates release.

Thomas, J.-P.; Allali, H.; Debré, O.; Lagrange, B.; Nsouli, B.; Oladipo, A. A.

1996-01-01

248

Spontaneous” desorption: A controlled phenomenon for surface analysis application? Part I: New evidence for a sputtering process induced by a well localized field enhanced desorption  

NASA Astrophysics Data System (ADS)

The mechanism of Spontaneous Desorption Mass Spectrometry (SOMS) has been investigated through the use of extraction electrodes with circular aperture, in place of the more conventional grid system. High emission rates of contaminant and sample specific anions have been recorded from reference materials like CsI and phenylalanine. It is shown that the emission rate is controlled by the existence and the characteristics of the aperture edge such as sharpness or (and) rugosity. Geometrical shape and material composition of this well localized region also influence the emission rate and ion yields. Experimentally, the sample emitting zone has been determined in two ways: (1) from the variation of the emission yield of sample specific ions as a function of the deposit diameter and (2) from the lateral distribution of impacts of these ions after their flight path. Both experiments clearly show that this emitting zone (impact zone of the primaries) has a ring shape related to the circular aperture parameters. SIMION ion trajectory simulations and field strength calculations demonstrate that the primary ions are mostly emitted from the well defined edges (inner and outer) of the electrode. The emission rate is shown to decrease rapidly with time after the application of the extraction potential indicating both a degradation of the edge sharpness or microtips density and a decrease of adsorbates release.

Allali, H.; Debré, O.; Lagrange, B.; Nsouli, B.; Oladipo, A. A.; Thomas, J.-P.

1996-01-01

249

Changes in children's nature-based experiences near home: from spontaneous play to adult-controlled, planned and organised activities  

Microsoft Academic Search

A qualitative case study from Brumunddalen, Norway, indicates that children's use of nature areas near their homes have changed substantially from being spontaneous and self-initiated to being part of planned, organised and adult-controlled activities. This study explores the association between changes in outdoor play and wider patterns of change in childhood today, as increasing amounts of play time is spent

Margrete Skår; Erling Krogh

2009-01-01

250

Enhancement of optical gain and amplified spontaneous emission due to waveguide geometry in the conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene  

NASA Astrophysics Data System (ADS)

We report enhanced amplified spontaneous emission (ASE) and optical gain performance in a conjugated polymer (CP)-based thin film waveguide (WG) Si(100)/SiO2/poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) by encapsulating the active layer with a transparent dielectric film of poly(methyl methacrylate) (PMMA). With index matched SiO2 and PMMA claddings, symmetric WGs are formed that exhibit increased mode confinement and reduced propagation loss enabling lower ASE threshold (40%) and higher optical gain (50%) compared to Si(100)/SiO2/MEH-PPV/air asymmetric WGs. An extremely large net gain coefficient of 500 cm-1 is achieved under picosecond pulse excitation, which is >4× larger than values previously reported in the literature. Fabrication of symmetric WGs requires no complex processing techniques, thus offering a simple, low-cost approach for effectively controlling the ASE behavior of CP-based WGs and related optical devices.

Lampert, Zach E.; Papanikolas, John M.; Lewis Reynolds, C.

2013-02-01

251

Ongoing Spontaneous Activity Controls Access to Consciousness: A Neuronal Model for Inattentional Blindness  

Microsoft Academic Search

Even in the absence of sensory inputs, cortical and thalamic neurons can show structured patterns of ongoing spontaneous activity, whose origins and functional significance are not well understood. We use computer simulations to explore the conditions under which spontaneous activity emerges from a simplified model of multiple interconnected thalamocortical columns linked by long-range, top-down excitatory axons, and to examine its

Stanislas Dehaene; Jean-Pierre Changeux

2005-01-01

252

COMPUTER-CONTROLLED, REAL-TIME AUTOMOBILE EMISSIONS MONITORING SYSTEM  

EPA Science Inventory

A minicomputer controlled automotive emissions sampling and analysis system (the Real-Time System) was developed to determine vehicular modal emissions over various test cycles. This data acquisition system can sample real-time emissions at a rate of 10 samples/s. A buffer utiliz...

253

Unregulated emissions from a heavy-duty diesel engine with various fuels and emission control systems.  

PubMed

This study evaluated the effects of various combinations of fuels and emission control technologies on exhaust emissions from a heavy-duty diesel engine tested on an engine dynamometer. Ten fuels were studied in twenty four combinations of fuel and emission control technology configurations. Emission control systems evaluated were diesel oxidation catalyst (DOC), continuously regenerating diesel particulate filter (CRDPF), and the CRDPF coupled with an exhaust gas recirculation system (EGRT). The effects of fuel type and emission control technology on emissions of benzene, toluene, ethylbenzene, xylene (BTEX), and 1,3-butadiene, elemental carbon and organic carbon (EC/OC), carbonyls, polycyclic aromatic hydrocarbons (PAHs), and nitro-PAHs (n-PAHs) are presented in this paper. Regulated gaseous criteria pollutants of total hydrocarbons (THC), carbon monoxide (CO), oxides of nitrogen (NO(x)) and particulate matter (PM) emissions have been reported elsewhere. In general, individual unregulated emission with a CRDPF or an EGRT system is similar (at very low emission level) or much lower than that operating solely with a DOC and choosing a "best" fuel. The water emulsion PuriNO(x) fuel exhibited higher BTEX, carbonyls and PAHs emissions compared to other ultralow sulfur diesel (ULSD) fuels tested in this study while n-PAH emissions were comparable to that from other ULSD fuels. Naphthalene accounted for greater than 50% of the total PAH emissions in this study and there was no significant increase of n-PAHs with the usage of CRDPF. PMID:17711220

Tang, Shida; Frank, Brian P; Lanni, Thomas; Rideout, Greg; Meyer, Norman; Beregszaszy, Chris

2007-07-15

254

Emissions control for ground power gas turbines  

NASA Technical Reports Server (NTRS)

The similarities and differences of emissions reduction technology for aircraft and ground power gas turbines is described. The capability of this technology to reduce ground power emissions to meet existing and proposed emissions standards is presented and discussed. Those areas where the developing aircraft gas turbine technology may have direct application to ground power and those areas where the needed technology may be unique to the ground power mission are pointed out. Emissions reduction technology varying from simple combustor modifications to the use of advanced combustor concepts, such as catalysis, is described and discussed.

Rudney, R. A.; Priem, R. J.; Juhasz, A. J.; Anderson, D. N.; Mroz, T. S.; Mularz, E. J.

1977-01-01

255

Quantum theory of two-photon correlated-spontaneous-emission lasers: Exact atom-field interaction Hamiltonian approach  

SciTech Connect

A quantum theory of two-photon correlated-spontaneous-emission lasers (CEL's) is developed, starting from the exact atom-field interaction Hamiltonian for cascade three-level atoms interacting with a single-mode radiation field. We consider the situation where the active atoms are prepared initially in a coherent superposition of three atomic levels and derive a master equation for the field-density operator by using a quantum theory for coherently pumped lasers. The master equation is transformed into a Fokker-Planck equation for the antinormal-ordering {ital Q} function. The drift coefficients of the Fokker-Planck equation enable us to study the steady-state operation of the two-photon CEL's analytically. We have studied both resonant two-photon CEL for which there is no threshold, and off-resonant two-photon CEL for which there exists a threshold. In both cases the initial atomic coherences provide phase locking, and squeezing in the phase quadrature of the field is found. The off-resonant two-photon CEL can build up from a vacuum when its linear gain is larger than the cavity loss (even without population inversion). Maximum squeezing is found in the no-population-inversion region with the laser intensities far below saturation in both cases, which are more than 90% for the resonant two-photon CEL and nearly 50% for the off-resonant one. Approximate steady-state {ital Q} functions are obtained for the resonant two-photon CEL and, in certain circumstances, for the off-resonant one.

Lu, N.; Zhu, S. (Center for Advanced Studies and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 (US))

1989-11-15

256

Spontaneous emission from radiative chiral nematic liquid crystals at the photonic band-gap edge: an investigation into the role of the density of photon states near resonance.  

PubMed

In this article, we investigate the spontaneous emission properties of radiating molecules embedded in a chiral nematic liquid crystal, under the assumption that the electronic transition frequency is close to the photonic edge mode of the structure, i.e., at resonance. We take into account the transition broadening and the decay of electromagnetic field modes supported by the so-called "mirrorless"cavity. We employ the Jaynes-Cummings Hamiltonian to describe the electron interaction with the electromagnetic field, focusing on the mode with the diffracting polarization in the chiral nematic layer. As known in these structures, the density of photon states, calculated via the Wigner method, has distinct peaks on either side of the photonic band gap, which manifests itself as a considerable modification of the emission spectrum. We demonstrate that, near resonance, there are notable differences between the behavior of the density of states and the spontaneous emission profile of these structures. In addition, we examine in some detail the case of the logarithmic peak exhibited in the density of states in two-dimensional photonic structures and obtain analytic relations for the Lamb shift and the broadening of the atomic transition in the emission spectrum. The dynamical behavior of the atom-field system is described by a system of two first-order differential equations, solved using the Green's-function method and the Fourier transform. The emission spectra are then calculated and compared with experimental data. PMID:23848702

Mavrogordatos, Th K; Morris, S M; Wood, S M; Coles, H J; Wilkinson, T D

2013-06-01

257

SUMMARY REPORT CONTROL OF NOX EMISSIONS BY REBURNING  

EPA Science Inventory

This report covers NOx control employing reburning technology: A new, effective method of controlling NOx emissions from a wide range of stationary combustion sources including large, coal-fired, utility boilers. Although reburning potentially is applicable ...

258

Control of Group Velocity via Spontaneous Generated Coherence and Kerr Nonlinearity  

NASA Astrophysics Data System (ADS)

A four-level N-type atomic medium is considered to study the effect of spontaneous generated coherence (SGC) and Kerr nonlinearity on light pulse propagation. A light pulse is propagating inside the medium where each atom follows four-level N-type atom-field configuration of rubidium (85Rb) atom. The atom-field interaction leads to electromagnetically induced transparency (EIT) process. The atom-field interaction is accompanied by normal dispersion and in the presence of SGC and Kerr nonlinearity the dispersion property of the proposed atomic medium is modified, which leads to enhancement of positive group index of the medium. The enhancement of positive group index then leads to slow group velocity inside the medium. A more slow group velocity is also investigated by incorporated the collective effect of SGC and Kerr nonlinearity. The control of group velocity inside a four-level N-type atomic medium via collective effect of SGC and Kerr nonlinearity is the major part of this work.

Hazrat, Ali; Iftikhar, Ahmad; Ziauddin

2014-09-01

259

Isoflurane anesthesia in sandhill cranes (Grus canadensis): minimal anesthetic concentration and cardiopulmonary dose-response during spontaneous and controlled breathing.  

PubMed

Information on species differences in responses to inhalation anesthetics has been established in a variety of mammalian and non-mammalian species, but comparable studies have not been reported in birds. The purpose of this study was to determine minimal anesthetic concentration and cardiopulmonary concentration-response effects of isoflurane in Sandhill cranes. Six cranes were anesthetized with isoflurane in oxygen. Gases sampled through a polyethylene tube inserted to the distal end of an endotracheal tube were used for measurements of isoflurane concentrations using an infrared gas analyzer. Body temperature was maintained at 40 +/- 0.5 degrees C. The minimal anesthetic concentration for isoflurane was determined during spontaneous ventilation, and concentration-response data were collected at 1, 1.5, and 2.0 times the minimal anesthetic concentration. Concentration-response data were repeated during mechanically controlled breathing with PaCO2 maintained between 27 and 35 mm Hg. The minimal anesthetic concentration for isoflurane was 1.34 +/- 0.14 vol% (mean +/- SD). Concentration-dependent respiratory depression during spontaneous breathing was evidenced in all cranes by an increase in PaCO2. Isoflurane induced apnea in two of the cranes during spontaneous ventilation at 2 times the minimal anesthetic concentration. As the concentration of isoflurane was increased, mean arterial blood pressure decreased during both spontaneous and controlled ventilation. Mean arterial blood pressure was higher during controlled ventilation than during spontaneous ventilation. The minimal anesthetic concentration for isoflurane in Sandhill cranes is similar to values for isoflurane minimal anesthetic concentration in mammals. Isoflurane has dose-dependent effects on cardiopulmonary function qualitatively similar to those observed in mammals. PMID:2929984

Ludders, J W; Rode, J; Mitchell, G S

1989-04-01

260

Controlled and spontaneous magnetic field generation in a gun-driven spheromak  

SciTech Connect

In the Sustained Spheromak Physics Experiment, SSPX [E. B. Hooper, D. Pearlstein, and D. D. Ryutov, Nucl. Fusion 39, 863 (1999)], progress has been made in understanding the mechanisms that generate fields by helicity injection. SSPX injects helicity (linked magnetic flux) from 1 m diameter magnetized coaxial electrodes into a flux-conserving confinement region. Control of magnetic fluctuations ({delta}B/B{approx}1% on the midplane edge) yields T{sub e} profiles peaked at >200 eV. Trends indicate a limiting beta ({beta}{sub e}{approx}4%-6%), and so we have been motivated to increase T{sub e} by operating with stronger magnetic field. Two new operating modes are observed to increase the magnetic field: (A) Operation with constant current and spontaneous gun voltage fluctuations. In this case, the gun is operated continuously at the threshold for ejection of plasma from the gun: stored magnetic energy of the spheromak increases gradually with {delta}B/B{approx}2% and large voltage fluctuations ({delta}V{approx}1 kV), giving a 50% increase in current amplification, I{sub tor}/I{sub gun}. (B) Operation with controlled current pulses. In this case, spheromak magnetic energy increases in a stepwise fashion by pulsing the gun, giving the highest magnetic fields observed for SSPX ({approx}0.7 T along the geometric axis). By increasing the time between pulses, a quasisteady sustainment is produced (with periodic good confinement), comparing well with resistive magnetohydrodynamic simulations. In each case, the processes that transport the helicity into the spheromak are inductive and exhibit a scaling of field with current that exceeds those previously obtained. We use our newly found scaling to suggest how to achieve higher temperatures with a series of pulses.

Woodruff, S.; Cohen, B.I.; Hooper, E.B.; Mclean, H.S.; Stallard, B.W.; Hill, D.N.; Holcomb, C.T.; Romero-Talamas, C.; Wood, R.D.; Cone, G.; Sovinec, C.R. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); California Institute of Technology, Pasadena, California 91125 (United States); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); University of Wisconsin, Madison, Wisconsin 53706 (United States)

2005-05-15

261

Controlled and Spontaneous Magnetic Field Generation in a Gun-Driven Spheromak  

SciTech Connect

In the Sustained Spheromak Physics Experiment, SSPX, progress has been made in understanding the mechanisms that generate fields by helicity injection. SSPX injects helicity (linked magnetic flux) from 1-m diameter magnetized coaxial electrodes into a flux-conserving confinement region. Control of magnetic fluctuations ({delta}B/B{approx}1% on the midplane edge) yields T{sub e} profiles peaked at > 200eV. Trends indicate a limiting beta ({beta}{sub e} {approx} 4-6%), and so we have been motivated to increase T{sub e} by operating with stronger magnetic field. Two new operating modes are observed to increase the magnetic field: (A) Operation with constant current and spontaneous gun voltage fluctuations. In this case, the gun is operated continuously at the threshold for ejection of plasma from the gun: stored magnetic energy of the spheromak increases gradually with {delta}B/B {approx}2% and large voltage fluctuations ({delta}V {approx} 1kV), giving a 50% increase in current amplification, I{sub tor}/I{sub gun}. (B) Operation with controlled current pulses. In this case, spheromak magnetic energy increases in a stepwise fashion by pulsing the gun, giving the highest magnetic fields observed for SSPX ({approx}0.7T along the geometric axis). By increasing the time between pulses, a quasi-steady sustainment is produced (with periodic good confinement), comparing well with resistive MHD simulations. In each case, the processes that transport the helicity into the spheromak are inductive and exhibit a scaling of field with current that exceeds those previously obtained. We use our newly found scaling to suggest how to achieve higher temperatures with a series of pulses.

Woodruff, S; Cohen, B I; Hooper, E B; McLean, H S; Stallard, B W; Hill, D N; Holcomb, C T; Romero-Talamas, C; Wood, R D; Cone, G; Sovinec, C R

2004-10-01

262

Controlled and spontaneous magnetic field generation in a gun-driven spheromak  

NASA Astrophysics Data System (ADS)

In the Sustained Spheromak Physics Experiment, SSPX [E. B. Hooper, D. Pearlstein, and D. D. Ryutov, Nucl. Fusion 39, 863 (1999)], progress has been made in understanding the mechanisms that generate fields by helicity injection. SSPX injects helicity (linked magnetic flux) from 1 m diameter magnetized coaxial electrodes into a flux-conserving confinement region. Control of magnetic fluctuations (?B /B˜1% on the midplane edge) yields Te profiles peaked at >200eV. Trends indicate a limiting beta (?e˜4%-6%), and so we have been motivated to increase Te by operating with stronger magnetic field. Two new operating modes are observed to increase the magnetic field: (A) Operation with constant current and spontaneous gun voltage fluctuations. In this case, the gun is operated continuously at the threshold for ejection of plasma from the gun: stored magnetic energy of the spheromak increases gradually with ?B /B˜2% and large voltage fluctuations (?V˜1kV), giving a 50% increase in current amplification, Itor/Igun. (B) Operation with controlled current pulses. In this case, spheromak magnetic energy increases in a stepwise fashion by pulsing the gun, giving the highest magnetic fields observed for SSPX (˜0.7T along the geometric axis). By increasing the time between pulses, a quasisteady sustainment is produced (with periodic good confinement), comparing well with resistive magnetohydrodynamic simulations. In each case, the processes that transport the helicity into the spheromak are inductive and exhibit a scaling of field with current that exceeds those previously obtained. We use our newly found scaling to suggest how to achieve higher temperatures with a series of pulses.

Woodruff, S.; Cohen, B. I.; Hooper, E. B.; Mclean, H. S.; Stallard, B. W.; Hill, D. N.; Holcomb, C. T.; Romero-Talamas, C.; Wood, R. D.; Cone, G.; Sovinec, C. R.

2005-05-01

263

Gaseous emissions from plants in controlled environments  

NASA Technical Reports Server (NTRS)

Plant growth in a controlled ecological life support system may entail the build-up over extended time periods of phytotoxic concentrations of volatile organic compounds produced by the plants themselves. Ethylene is a prominent gaseous emission of plants, and is the focus of this report. The objective was to determine the rate of ethylene release by spring wheat, white potato, and lettuce during early, middle, and late growth stages, and during both the light and dark segments of the diurnal cycle. Plants grown hydroponically using the nutrient film technique were covered with plexiglass containers for 4 to 6 h. At intervals after enclosure, gas samples were withdrawn with a syringe and analyzed for ethylene with a gas chromatograph. Lettuce produced 10 to 100 times more ethylene than wheat or potato, with production rates ranging from 141 to 158 ng g-dry/wt/h. Wheat produced from 1.7 to 14.3 ng g-dry/wt/h, with senescent wheat producing the least amount and flowering wheat the most. Potatoes produced the least amount of ethylene, with values never exceeding 5 ng g-dry/wt/h. Lettuce and potatoes each produced ethylene at similar rates whether in dark period or light period. Ethylene sequestering of 33 to 43 percent by the plexiglass enclosures indicated that these production estimates may be low by one-third to one-half. These results suggest that concern for ethylene build-up in a contained atmosphere should be greatest when growing lettuce, and less when growing wheat or potato.

Dubay, Denis T.

1988-01-01

264

Detection and control of spontaneous heating in coal mine pillars -- A case study  

SciTech Connect

This US Bureau of Mines study examined spontaneous heating episodes in coal mine pillars in an active underground coal mine. The information obtained from these incidents was then analyzed to learn which sampling methods provided the earliest indication of pillar heating. The objective of this study was to discover if the location of future events of pillar spontaneous heating could be inferred from the available information. The spontaneous heating-prone area in this evaluation involved pillars located just in by the mine portals. Several detection methods were used to determine gas levels outside as well as inside the affected pillars. It was hoped that, by incorporating external and internal sampling methods into an organized program, locations undergoing spontaneous heat could be determined more readily. This study found that by drilling small-diameter boreholes into the pillars, then obtaining gas samples from the affected pillars, the ability to locate early spontaneous heating episodes was improved. However, the ability to accurately predict future spontaneous heat events remains in question.

Timko, R.J.; Derick, R.L.

1995-12-31

265

Correlation of angular light profiles of light-emitting diodes to spatial spontaneous emissions from photonic crystals  

NASA Astrophysics Data System (ADS)

Typically, photonic crystal light-emitting diodes employ shallow nanostructures which only higher-order optical modes can be interacted with. Here, both the shallow photonic crystals and nanohole arrays (etched through active layers) are fabricated, which serve to diffract, respectively, higher and lower optical modes in the active layer. Our results indicate that the photon lifetime can be controlled by adjusting the geometry of shallow nanostructures and nanohole arrays. The angular emission profiles are thus determined by the dominance of higher- and lower-order mode quality factors in the band structure.

Yin, Yu-Feng; Lin, Yen-Chen; Liu, Yi-Chen; Shen, Yi-Chun; Chiang, Hai-Pang; Huang, JianJang

2013-10-01

266

CONTROLLING NOX EMISSION FROM INDUSTRIAL SOURCES  

EPA Science Inventory

A number of regulatory actions focused on reducing NOx emissions from stationary combustion sources have been taken in the United States in the last decade. These actions include the Acid Rain NOx regulations, the Ozone Transport Commission's NOx ...

267

Temperature Dependence of Factors Controlling Isoprene Emissions  

NASA Technical Reports Server (NTRS)

We investigated the relationship of variability in the formaldehyde (HCHO) columns measured by the Aura Ozone Monitoring Instrument (OMI) to isoprene emissions in the southeastern United States for 2005-2007. The data show that the inferred, regional-average isoprene emissions varied by about 22% during summer and are well correlated with temperature, which is known to influence emissions. Part of the correlation with temperature is likely associated with other causal factors that are temperature-dependent. We show that the variations in HCHO are convolved with the temperature dependence of surface ozone, which influences isoprene emissions, and the dependence of the HCHO column to mixed layer height as OMI's sensitivity to HCHO increases with altitude. Furthermore, we show that while there is an association of drought with the variation in HCHO, drought in the southeastern U.S. is convolved with temperature.

Duncan, Bryan N.; Yoshida, Yasuko; Damon, Megan R.; Douglass, Anne R.; Witte, Jacquelyn C.

2009-01-01

268

Gas turbine combustion and emission control  

NASA Astrophysics Data System (ADS)

The fundamentals of combustion are discussed in the context of gaseous and liquid fuels and gas turbine fuels. Methods for reducing the emission of pollutants in gas turbines are considered. These emissions are carbon monoxide, unburnt hydrocarbons, smoke/soot, nitrogen oxides, sulphur oxides, and carbon dioxide. The focus is on nitrogen oxides. The general principles of combustor and burner design are considered: aero/can type combustors, silo combustors, and annular combustors. Premix and diffusion flames are discussed.

Schetter, B.

269

Controlling quantum-dot light absorption and emission by a surface-plasmon field.  

PubMed

The possibility for controlling both the probe-field optical gain and absorption, as well as photon conversion by a surface-plasmon-polariton near field is explored for a quantum dot located above a metal surface. In contrast to the linear response in the weak-coupling regime, the calculated spectra show an induced optical gain and a triply-split spontaneous emission peak resulting from the interference between the surface-plasmon field and the probe or self-emitted light field in such a strongly-coupled nonlinear system. Our result on the control of the mediated photon-photon interaction, very similar to the 'gate' control in an optical transistor, may be experimentally observable and applied to ultra-fast intrachip/interchip optical interconnects, improvement in the performance of fiber-optic communication networks, and developments of optical digital computers and quantum communications. PMID:25401904

Huang, Danhong; Easter, Michelle; Gumbs, Godfrey; Maradudin, A A; Lin, Shawn-Yu; Cardimona, D A; Zhang, Xiang

2014-11-01

270

Controlled and Spontaneous Magnetic Field Generation in a Gun-Driven Spheromak.  

NASA Astrophysics Data System (ADS)

In the Sustained Spheromak Physics Experiment, SSPX, progress has been made in understanding the mechanisms that generate fields by helicity injection [1][2]. SSPX injects helicity (linked magnetic flux) from a 1-m diameter magnetized coaxial gun into a flux-conserving confinement region. Control of magnetic fluctuations (?B/B<1%) yields Te profiles peaked at 200eV (2x higher than previously obtained [3]). Trends indicate a limiting beta (? _e ˜ 4%), so further increases of Te requires operating with higher fields. Two new operating modes are observed to increase the magnetic field: with constant current and spontaneous gun voltage fluctuations; and with current pulses to harness specific processes. In the first case, the gun is operated continuously at the ejection threshold: stored magnetic energy of the spheromak increases gradually with ?B/B ˜2% and large voltage fluctuations (?V ˜1kV), giving a 50% increase in current amplification, I_tor/I_gun. In the second case, we show that the B-field can be increased in a stepwise fashion by pulsing the gun. By increasing the timing between pulses, a quasi-steady sustainment is produced (with periodic good confinement), which we compare with 3D MHD simulations [4]. In each case, the processes that transport the helicity into the spheromak are inductive. Internal magnetic probing helps identify these processes and also show that the discharge in the gun can be asymmetric, causing a practical limitation in applying helicity balance. [1] S. Woodruff et al Phys. Rev. Lett. 90 095001-1 (2003); [2] B. W. Stallard et al Phys. of Plasmas 10 2912 (2003); [3] H. S. McLean, et al Phys. Rev. Lett. 88 125004 (2002); [4] R. Cohen et al to appear in Nuclear Fusion

Woodruff, Simon

2003-10-01

271

CO emissions in China: Uncertainties and implications of improved energy efficiency and emission control  

NASA Astrophysics Data System (ADS)

A bottom-up methodology and an improved database of emission factors combining the latest domestic field measurements are developed to estimate the emissions of anthropogenic CO from China at national and provincial levels. The CO emission factors for major economic sectors declined to varying degrees from 2005 to 2009, attributed to improved energy efficiency and/or emission control regulations. Total national CO emissions are estimated at 173 Tg for 2005 and have been relatively stable for subsequent years, despite fast growth of energy consumption and industrial production. While industry and transportation sources dominated CO emissions in developed eastern and north-central China, residential combustion played a much greater role in the less developed western provinces. The uncertainties of national Chinese CO emissions are quantified using Monte Carlo simulation at -20% to +45% (95% confidence interval). Due to poor understanding of emission factors and activity levels for combustion of solid fuels, the largest uncertainties are found for emissions from the residential sector. The trends of bottom-up emissions compare reasonably to satellite observation of CO columns and to ground observations of CO2-CO correlation slopes. The increase in the ratio for emissions of CO2 relative to CO suggests that China has successfully improved combustion efficiencies across its economy in recent years, consistent with national policies to improve energy efficiency and to control criteria air pollutants.

Zhao, Yu; Nielsen, Chris P.; McElroy, Michael B.; Zhang, Lin; Zhang, Jie

2012-03-01

272

Spontaneous pushing to prevent postpartum urinary incontinence: a randomized, controlled trial  

PubMed Central

Introduction and hypothesis The risk for urinary incontinence can be 2.6-fold greater in women after pregnancy and childbirth compared with their never-pregnant counterparts, with the incidence increasing with parity. We tested the hypothesis that the incidence of de novo postpartum urinary incontinence in primiparous women is reduced with the use of spontaneous pushing alone or in combination with perineal massage compared with women who experienced traditional directed pushing for second-stage management. Methods This was a prospective clinical trial enrolling and randomizing 249 women into a four-group design: (1) routine care with coached or directed pushing, (2) spontaneous self-directed pushing, (3) prenatal perineal massage initiated in the third trimester, and (4) the combination of spontaneous pushing plus perineal massage. Self-report of incontinence was assessed using analysis of variance (ANOVA) and covariance (ANCOVA) models in 145 remaining women at 12 months postpartum using the Leakage Index, which is sensitive to minor leakage. Results No statistical difference in the incidence of de novo postpartum incontinence was found based on method of pushing (spontaneous/directed) (P value=0.57) or in combination with prenatal perineal massage (P value=0.57). Fidelity to pushing treatment of type was assessed and between-groups crossover detected. Conclusions Spontaneous pushing did not reduce the incidence of postpartum incontinence experienced by women 1 year after their first birth due to high cross-over between randomization groups. PMID:22829349

Miller, Janis M.; Guo, Ying; Ashton-Miller, James A.; DeLancey, John O. L.; Sampselle, Carolyn M.

2014-01-01

273

Cost-effective control of SO 2 emissions in Asia  

Microsoft Academic Search

Despite recent efforts to limit the growth of SO2 emissions in Asia, the negative environmental effects of sulphur emissions are likely to further increase in the future. This paper presents an extension of the RAINS-Asia integrated assessment model for acidification in Asia with an optimisation routine that can be used to identify cost-effective emission control strategies that achieve environmental targets

J. Cofala; M. Amann; F. Gyarfas; W Schoepp; J. C. Boudri; L. Hordijk; C. Kroeze; Li Junfeng; D. Dai Lin; T. S. Panwar; S. Gupta

2004-01-01

274

Emission control devices, fuel additive, and fuel composition changes.  

PubMed Central

Emission control devices are installed to meet the exhaust standards of the Clean Air Act for carbon monoxide and hydrocarbons, and it is necessary to know, from a public health point of view, how exhaust emissions may be affected by changes in fuel additives and fuel composition. Since these topics are concerned with developing technologies, the available literature on exhaust emission characteristics and the limited information on health effects, is reviewed. PMID:71235

Piver, W T

1977-01-01

275

Alternative control technology document for bakery oven emissions. Final report  

SciTech Connect

The document was produced in response to a request by the baking industry for Federal guidance to assist in providing a more uniform information base for State decision-making with regard to control of bakery oven emissions. The information in the document pertains to bakeries that produce yeast-leavened bread, rolls, buns, and similar products but not crackers, sweet goods, or baked foodstuffs that are not yeast leavened. Information on the baking processes, equipment, operating parameters, potential emissions from baking, and potential emission control options are presented. Catalytic and regenerative oxidation are identified as the most appropriate existing control technologies applicable to VOC emissions from bakery ovens. Cost analyses for catalytic and regenerative oxidation are included. A predictive formula for use in estimating oven emissions has been derived from source tests done in junction with the development of the document. Its use and applicability are described.

Sanford, C.W.

1992-12-01

276

Sulfur oxide adsorbents and emissions control  

DOEpatents

High capacity sulfur oxide absorbents utilizing manganese-based octahedral molecular sieve (Mn--OMS) materials are disclosed. An emissions reduction system for a combustion exhaust includes a scrubber 24 containing these high capacity sulfur oxide absorbents located upstream from a NOX filter 26 or particulate trap.

Li, Liyu (Richland, WA); King, David L. (Richland, WA)

2006-12-26

277

Controlling air toxics emissions poses challenges  

Microsoft Academic Search

Emissions from power plants can include trace levels of air toxics such as mercury, selenium and arsenic that exist either partially or completely as a vapor in the flue-gas exit discharge. Other heavy metals such as lead and nickel, which are small, hard to collect particulates, also may be included in the discharged flue gas. Industry and government researchers have

R. Lausman; L. Lavely

1997-01-01

278

CONTROL OF MOTOR VEHICLE EMISSIONS - THE U.S. EXPERIENCE  

EPA Science Inventory

An historical overview of the U.S. experience with controlling emissions from highway motor vehicles is presented. he evolution of new motor vehicle emissions certification practice, end-of-assembly-line inspection, in-use surveillance and recall, inspection and maintenance, and ...

279

Programmable smart electron emission controller for hot filament  

Microsoft Academic Search

In electron ionization source, electrons are produced through thermionic emission by heating a wire filament, accelerating the electrons by high voltage, and ionizing the analyzed molecules. In such a system, one important parameter is the filament emission current that determines the ionization rate; therefore, one needs to regulate this current. On the one hand, fast responses control is needed to

Eli Flaxer

2011-01-01

280

Control of variable geometry turbocharged diesel engines for reduced emissions  

Microsoft Academic Search

The emission control problem for an automotive direct injected compression ignition (diesel) engine equipped with exhaust gas recirculation (EGR) and a variable geometry turbocharger (VGT) is considered. The objective is to operate the engine to meet driver's torque demand and minimize NOx emissions while at the same time avoiding visible smoke generation. It is demonstrated that the steady-state optimization of

Anna G. Stefanopoulou; Ilya Kolmanovsky; James S. Freudenberg

2000-01-01

281

PERFORMANCE OF EMISSIONS CONTROL SYSTEMS ON MUNICIPAL WASTE COMBUSTORS  

EPA Science Inventory

The paper reports results of several EPA-supported field evaluations of data on gaseous pollutant emissions from modern municipal waste combustors/incinerators and emissions control by flue gas cleaning systems. The results are presented in terms of acid gas (HCl and SO2), trace ...

282

Using Transfer of Stimulus Control Technology to Promote Generalization and Spontaneity of Language  

ERIC Educational Resources Information Center

Children with autism often use newly acquired language in restricted contexts and with limited variability. Instructional tactics that embed generalization technology have shown promise for increasing spontaneity, response variation, and the generalized use of language across settings, people, and materials. In this study, we explored the…

Spencer, Trina D.; Higbee, Thomas S.

2012-01-01

283

Wideband thulium-holmium-doped fiber source with combined forward and backward amplified spontaneous emission at 1600-2300??nm spectral band.  

PubMed

We have experimentally demonstrated two extremely wideband amplified spontaneous emission (ASE) sources. High bandwidth is achieved by combining the backward and forward ASEs generated in thulium-holmium-doped fiber using appropriate wideband couplers. The ASE source optimized for flat spectral power density covers a spectral range from 1527 to 2171 nm at a -10??dB level. The ASE source optimized for spectroscopy features an enhancement with respect to single-mode fiber (SMF) coupled halogen lamps within the spectral range from 1540 nm to more than 2340 nm covering the 800 nm bandwidth. PMID:24978559

Honzatko, Pavel; Baravets, Yauhen; Kasik, Ivan; Podrazky, Ondrej

2014-06-15

284

Raman-shifted KrF laser radiation with low amplified spontaneous emission for a rotational Raman daytime-temperature lidar  

SciTech Connect

Various configurations of a tunable two-stage KrF laser have been investigated for providing powerful laser pulses with very low amplified spontaneous emission (ASE). The lowest fraction (0.00017%) of ASE was attained with a single-pass amplifier and a phase-conjugate Brillouin mirror. The most suitable application envisaged for the laser source, i.e., remote daytime-temperature measurement by means of rotational Raman scattering, is a dedicated oscillator--amplifier configuration with an ASE of 0.005% at an output of 300 mJ. The very low values of ASE were measured with the aid of a thallium atomic-vapor filter.

Luckow, F.; Voss, E.; Zeyn, J.; Lahmann, W.; Weitkamp, C.; Michaelis, W. (Institut fuer Physik, GKSS-Forschungszentrum Geesthacht GmbH, D-21502 Geesthacht (Germany))

1994-07-15

285

EUROPEAN ACTIVITIES IN SO2 AND NOX EMISSION CONTROL  

EPA Science Inventory

The paper gives updated details of major flue gas desulfurization (FGD) and nitrogen oxide (NOx) control installations in the Federal Republic of Germany (West Germany) for coal-fired boilers. The paper reviews applicable government regulations limiting stack emissions, provides ...

286

Self-organized global control of carbon emissions  

NASA Astrophysics Data System (ADS)

There is much disagreement concerning how best to control global carbon emissions. We explore quantitatively how different control schemes affect the collective emission dynamics of a population of emitting entities. We uncover a complex trade-off which arises between average emissions (affecting the global climate), peak pollution levels (affecting citizens’ everyday health), industrial efficiency (affecting the nation’s economy), frequency of institutional intervention (affecting governmental costs), common information (affecting trading behavior) and market volatility (affecting financial stability). Our findings predict that a self-organized free-market approach at the level of a sector, state, country or continent can provide better control than a top-down regulated scheme in terms of market volatility and monthly pollution peaks. The control of volatility also has important implications for any future derivative carbon emissions market.

Zhao, Zhenyuan; Fenn, Daniel J.; Hui, Pak Ming; Johnson, Neil F.

2010-09-01

287

A Novel New Approach to VOC and HAP Emission Control  

E-print Network

HAP (Hazardous Air Pollutant) and VOC (Volatile Organic Compound) thermal emission control devices (ECD) usually require large amounts of energy to operate. They also require large capital investments in heat recovery options and large amounts...

McGinness, M.

288

CONTROL OF TRACE METAL EMISSIONS DURING COAL COMBUSTION  

Microsoft Academic Search

Emissions of toxic trace metals in the form of metal fumes or submicron particulates from a coal-fired combustion source have received greater environmental and regulatory concern over the past years. Current practice of controlling these emissions is to collect them at the cold-end of the process by air-pollution control devices (APCDs) such as electrostatic precipitators and baghouses. However, trace metal

THOMAS C. HO

1998-01-01

289

Heavy metals emission from controlled combustion of PVC  

E-print Network

HEAVY METALS EMISSION FROM CONTROLLED COMBUSTION OF PVC A Thesis by MOHAMMED A. EL-AYYOUBI Submitted to the Office of Graduate Studies of Texas Ag M University in partial fulfillment of the requirement for the degas ee of' MASTER OF SCIENCE... August 1989 Major Subject: Safety Engineering HEAVY METALS EMISSION FROM CONTROLLED COMBUSTION OF PVC A Thesis by MOHAMMED A. EL-AYYOUBI Approved as to style and content by: John P. Wa r Chair of Committee) Waymo . Johnston (Member) Cesar...

El-Ayyoubi, Mohammed A.

2012-06-07

290

The Control of NOx Emissions from Combustion and Incinerators  

E-print Network

of combustion modifications, including staged combustion and reburning, for the control of nitrogen oxide emissions from coal fired combustors is most often limited by problems due to carbon burnout or flame impingement. This paper presents new data... of combustion modifications, including staged combustion and reburning, for the control of nitrogen oxide emissions from coal fired combustors is most often limited by problems due to carbon burnout or flame impingement. This paper presents new data...

Heap, M. P.; Chen, S. L.; Seeker, W. R.; Pershing, D. W.

291

Emission current control system for multiple hollow cathode devices  

NASA Technical Reports Server (NTRS)

An emission current control system for balancing the individual emission currents from an array of hollow cathodes has current sensors for determining the current drawn by each cathode from a power supply. Each current sensor has an output signal which has a magnitude proportional to the current. The current sensor output signals are averaged, the average value so obtained being applied to a respective controller for controlling the flow of an ion source material through each cathode. Also applied to each controller are the respective sensor output signals for each cathode and a common reference signal. The flow of source material through each hollow cathode is thereby made proportional to the current drawn by that cathode, the average current drawn by all of the cathodes, and the reference signal. Thus, the emission current of each cathode is controlled such that each is made substantially equal to the emission current of each of the other cathodes. When utilized as a component of a multiple hollow cathode ion propulsion motor, the emission current control system of the invention provides for balancing the thrust of the motor about the thrust axis and also for preventing premature failure of a hollow cathode source due to operation above a maximum rated emission current.

Beattie, John R. (Inventor); Hancock, Donald J. (Inventor)

1988-01-01

292

40 CFR 63.325 - Determination of equivalent emission control technology.  

...Determination of equivalent emission control technology. 63.325 Section 63.325 Protection...Determination of equivalent emission control technology. (a) Any person requesting...illustrating the emission control technology, its operation and integration...

2014-07-01

293

40 CFR 63.325 - Determination of equivalent emission control technology.  

Code of Federal Regulations, 2010 CFR

...Determination of equivalent emission control technology. 63.325 Section 63.325 Protection...Determination of equivalent emission control technology. (a) Any person requesting...illustrating the emission control technology, its operation and integration...

2010-07-01

294

40 CFR 63.325 - Determination of equivalent emission control technology.  

Code of Federal Regulations, 2012 CFR

...Determination of equivalent emission control technology. 63.325 Section 63.325 Protection...Determination of equivalent emission control technology. (a) Any person requesting...illustrating the emission control technology, its operation and integration...

2012-07-01

295

40 CFR 63.325 - Determination of equivalent emission control technology.  

Code of Federal Regulations, 2013 CFR

...Determination of equivalent emission control technology. 63.325 Section 63.325 Protection...Determination of equivalent emission control technology. (a) Any person requesting...illustrating the emission control technology, its operation and integration...

2013-07-01

296

40 CFR 63.325 - Determination of equivalent emission control technology.  

Code of Federal Regulations, 2011 CFR

...Determination of equivalent emission control technology. 63.325 Section 63.325 Protection...Determination of equivalent emission control technology. (a) Any person requesting...illustrating the emission control technology, its operation and integration...

2011-07-01

297

40 CFR 57.504 - Continuing evaluation of fugitive emission control measures.  

Code of Federal Regulations, 2012 CFR

...evaluation of fugitive emission control measures. 57.504 Section 57...evaluation of fugitive emission control measures. Each NSO shall require...effectiveness of the fugitive emission control measures implemented pursuant to §...

2012-07-01

298

40 CFR 57.504 - Continuing evaluation of fugitive emission control measures.  

Code of Federal Regulations, 2011 CFR

...evaluation of fugitive emission control measures. 57.504 Section 57...evaluation of fugitive emission control measures. Each NSO shall require...effectiveness of the fugitive emission control measures implemented pursuant to §...

2011-07-01

299

40 CFR 57.504 - Continuing evaluation of fugitive emission control measures.  

Code of Federal Regulations, 2010 CFR

...evaluation of fugitive emission control measures. 57.504 Section 57...evaluation of fugitive emission control measures. Each NSO shall require...effectiveness of the fugitive emission control measures implemented pursuant to §...

2010-07-01

300

40 CFR 57.504 - Continuing evaluation of fugitive emission control measures.  

Code of Federal Regulations, 2013 CFR

...evaluation of fugitive emission control measures. 57.504 Section 57...evaluation of fugitive emission control measures. Each NSO shall require...effectiveness of the fugitive emission control measures implemented pursuant to §...

2013-07-01

301

Programmable smart electron emission controller for hot filament.  

PubMed

In electron ionization source, electrons are produced through thermionic emission by heating a wire filament, accelerating the electrons by high voltage, and ionizing the analyzed molecules. In such a system, one important parameter is the filament emission current that determines the ionization rate; therefore, one needs to regulate this current. On the one hand, fast responses control is needed to keep the emission current constant, but on the other hand, we need to protect the filament from damage that occurs by large filaments current transients and overheating. To control our filament current and emission current, we developed a digital circuit based on a digital signal processing controller that has several modes of operation. We used a smart algorithm that has a fast response to a small signal and a slow response to a large signal. In addition, we have several protective measures that prevent the current from reaching unsafe values. PMID:21361637

Flaxer, Eli

2011-02-01

302

Programmable smart electron emission controller for hot filament  

NASA Astrophysics Data System (ADS)

In electron ionization source, electrons are produced through thermionic emission by heating a wire filament, accelerating the electrons by high voltage, and ionizing the analyzed molecules. In such a system, one important parameter is the filament emission current that determines the ionization rate; therefore, one needs to regulate this current. On the one hand, fast responses control is needed to keep the emission current constant, but on the other hand, we need to protect the filament from damage that occurs by large filaments current transients and overheating. To control our filament current and emission current, we developed a digital circuit based on a digital signal processing controller that has several modes of operation. We used a smart algorithm that has a fast response to a small signal and a slow response to a large signal. In addition, we have several protective measures that prevent the current from reaching unsafe values.

Flaxer, Eli

2011-02-01

303

Spectroscopic studies, fluorescence quenching by molecular oxygen and amplified spontaneous emission of 1,4-bis [2-(2-pyridyl) vinyl] benzene (P2VB) diolefinic laser dye  

NASA Astrophysics Data System (ADS)

The UV-visible electronic absorption spectra, molar absorptivity, fluorescence spectra, fluorescence quantum yield and excited state lifetime of 1,4-bis [2-(2-pyridyl) vinyl] benzene P2VB were measured in different solvents. The fluorescence quenching of P2VB by molecular oxygen was also studied using lifetime measurements. A 2 × 10-4 mol dm-3 solution of P2VB in dimethyl formamide (DMF) gave amplified spontaneous emission (ASE) in blue spectral region with emission maximum at 420 nm upon pumping by 337.1 nitrogen laser pulse. The photochemical quantum yields (?c) of trans-cis photoisomerization of P2VB were calculated in different organic solvents. The photoreactivity of P2VB are also studied PMMA matrix.

El-Daly, Samy A.; Ebeid, E. M.

2014-04-01

304

Electromagnetically induced grating based on the giant Kerr nonlinearity controlled by spontaneously generated coherence.  

PubMed

We propose a scheme for realizing electromagnetically induced grating via the giant Kerr nonlinearity in a coherently driven four-level system with spontaneously generated coherence. In the presence of spontaneously generated coherence, Kerr nonlinearity can be enhanced with vanishing linear absorption. Thus, with a standing-wave coupling field, one can achieve a pure absorption grating, which leads the probe field to gather the zero-order direction when the detuning of the coupling field is on resonance. Moreover, we can obtain a pure phase grating, which diffracts a weak probe light into the first-order direction and the second-order direction when the detuning of the coupling field is off resonance. PMID:23842169

Ba, Nuo; Wang, Lei; Wu, Xiang-Yao; Liu, Xiao-Jing; Wang, Hai-Hua; Cui, Cui-Li; Li, Ai-Jun

2013-06-20

305

Historical evaluation of vehicle emission control in Guangzhou based on a multi-year emission inventory  

NASA Astrophysics Data System (ADS)

The Guangzhou government adopted many vehicle emission control policies and strategies during the five-year preparation (2005-2009) to host the 2010 Asian Games. This study established a multi-year emission inventory for vehicles in Guangzhou during 2005-2009 and estimated the uncertainty in total vehicle emissions by taking the assumed uncertainties in fleet-average emission factors and annual mileage into account. In 2009, the estimated total vehicle emissions in Guangzhou were 313 000 (242 000-387 000) tons of CO, 60 900 (54 000-70 200) tons of THC, 65 600 (56 800-74 100) tons of NOx and 2740 (2100-3400) tons of PM10. Vehicle emissions within the urban area of Guangzhou were estimated to be responsible for ˜40% of total gaseous pollutants and ˜25% of total PM10 in the entire city. Although vehicle use intensity increased rapidly in Guangzhou during 2005-2009, vehicle emissions were estimated to have been reduced by 12% for CO, 21% for THC and 20% for PM10 relative to those in 2005. NOx emissions were estimated to have remained almost constant during this period. Compared to the "without control" scenario, 19% (15%-23%) of CO, 20% (18%-23%) of THC, 9% (8%-10%) of NOx and 16% (12%-20%) of PM10 were estimated to have been mitigated from a combination of the implementation of Euro III standards for light-duty vehicles (LDVs) and heavy-duty diesel vehicles and improvement of fuel quality. This study also evaluated several enhanced vehicle emission control actions taken recently. For example, the enhanced I/M program for LDVs was estimated to reduce 11% (9%-14%) of CO, 9% (8%-10%) of THC and 2% (2%-3%) of NOx relative to total vehicle emissions in 2009. Total emission reductions by temporary traffic controls for the Asian Games were estimated equivalent to 9% (7%-11%) of CO, 9% (8%-10%) of THC, 5% (5%-6%) of NOx and 10% (8%-13%) of PM10 estimated total vehicle emissions in 2009. Those controls are essential to further vehicle emission mitigation in Guangzhou required by the new National Ambient Air Quality Standards.

Zhang, Shaojun; Wu, Ye; Liu, Huan; Wu, Xiaomeng; Zhou, Yu; Yao, Zhiliang; Fu, Lixin; He, Kebin; Hao, Jiming

2013-09-01

306

Emission of orbital-angular-momentum-entangled photon pairs in a nonlinear ring fiber utilizing spontaneous parametric down-conversion  

NASA Astrophysics Data System (ADS)

We suggest the generation of photon pairs in a thermally induced nonlinear periodically poled silica fiber by spontaneous parametric down-conversion. Photons are generated directly in eigenstates of optical angular momentum. Photons in a pair can be entangled in these states as well as in frequencies. We identify suitable spatial and polarization modes giving an efficient nonlinear interaction. By changing the pump field properties both narrow- and broadband down-converted fields can be obtained.

Javůrek, D.; Svozilík, J.; Pe?ina, J.

2014-10-01

307

Emission of OAM entangled photon pairs in a nonlinear ring fiber utilizing spontaneous parametric down-conversion  

E-print Network

We suggest the generation of photon pairs in a thermally induced nonlinear periodically-poled silica fiber by spontaneous parametric down-conversion. Photons are generated directly in eigenstates of optical angular momentum. Photons in a pair can be entangled in these states as well as in frequencies. We identify suitable spatial and polarization modes giving an efficient nonlinear interaction. By changing the pump field properties both narrow- and broad-band down-converted fields can be obtained.

Jav?rek, D; Pe?ina, J

2014-01-01

308

Optical control of the emission direction of a quantum dot  

SciTech Connect

Using the helicity of a non-resonant excitation laser, control over the emission direction of an InAs/GaAs quantum dot is demonstrated. The quantum dot is located off-center in a crossed-waveguide structure, such that photons of opposite circular polarization are emitted into opposite waveguide directions. By preferentially exciting spin-polarized excitons, the direction of emission can therefore be controlled. The directional control is quantified by using the ratio of the intensity of the light coupled into the two waveguides, which reaches a maximum of ±35%.

Luxmoore, I. J., E-mail: i.j.luxmoore@exeter.ac.uk [College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom); Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Wasley, N. A.; Fox, A. M.; Skolnick, M. S. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom)] [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Ramsay, A. J. [Hitachi Cambridge Laboratory, Hitachi Europe Ltd, Cambridge CB3 OHE (United Kingdom)] [Hitachi Cambridge Laboratory, Hitachi Europe Ltd, Cambridge CB3 OHE (United Kingdom); Thijssen, A. C. T.; Oulton, R. [H. H. Wills Physics Laboratory and Department of Electrical and Electronic Engineering, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)] [H. H. Wills Physics Laboratory and Department of Electrical and Electronic Engineering, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Hugues, M. [Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom) [Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); CNRS-CRHEA, rue Bernard Grégory, 06560 Valbonne (France)

2013-12-09

309

CONTROL OF SULFUR EMISSIONS FROM OIL SHALE RETORTS  

EPA Science Inventory

The objectives of this study were to determine the best available control technology (BACT) for control of sulfur emissions from oil shale processing facilities and then to develop a design for a mobile slipstream pilot plant that could be used to test and demonstrate that techno...

310

CONTROL OF PARTICULATE EMISSIONS IN THE PRIMARY NONFERROUS METALS INDUSTRIES  

EPA Science Inventory

The purpose of the symposium on 'Control of Particulate Emissions in the Primary Nonferrous Metals Industries' was to provide a forum for the exchange of knowledge and new ideas on particulate control technology with emphasis on industrial applications of environmental particulat...

311

Low-Emissions Exhaust Quality Control System to Optimize  

E-print Network

are available for small scale systems, a system to control both temperature and overall flow rate and flow rate by injecting fuel and tempering air depending on the exhaust conditions, to matchLow-Emissions Exhaust Quality Control System to Optimize DG/CCHP Systems Renewable Energy Research

312

Biofiltration: An Innovative Air Pollution Control Technology For VOC Emissions  

Microsoft Academic Search

Biofiltration is a relatively recent air pollution control (APC) technology in which off-gases containing biodegradable volatile organic compounds (VOC) or inorganic air toxics are vented through a biologically active material. This technology has been successfully applied in Germany and The Netherlands in many full-scale applications to control odors, VOC and air toxic emissions from a wide range of industrial and

Gero Leson; Arthur M. Winer

1991-01-01

313

Cardiovascular effects of halothane anesthesia after diazepam and ketamine administration in beavers (Castor canadensis) during spontaneous or controlled ventilation.  

PubMed

Fourteen adult beavers (Castor canadensis) weighing 16.5 +/- 4.14 kg (mean +/- SD) were anesthetized for surgical implantation of radio telemetry devices. Beavers were anesthetized with diazepam (0.1 mg/kg) and ketamine (25 mg/kg) administered IM, which provided smooth anesthetic induction and facilitated tracheal intubation. Anesthesia was maintained with halothane in oxygen via a semiclosed circle anesthetic circuit. Values for heart rate, respiratory rate, esophageal temperature, direct arterial blood pressure, end-tidal halothane concentration, and end-tidal CO2 tension were recorded every 15 minutes during the surgical procedure. Arterial blood samples were collected every 30 minutes to determine pH, PaO2, and PaCO2. Values for plasma bicarbonate, total CO2, and base excess were calculated. Ventilation was spontaneous in 7 beavers and controlled to maintain normocapnia (PaCO2 approx 40 mm of Hg) in 7 others. Vaporizer settings were adjusted to maintain a light surgical plane of anesthesia. Throughout the surgical procedure, all beavers had mean arterial pressure less than 60 mm of Hg and esophageal temperature less than 35 C. Mean values for arterial pH, end-tidal CO2, PaO2, and PaCO2 were significantly (P less than 0.05) different in spontaneously ventilating beavers, compared with those in which ventilation was controlled. Respiratory acidosis during halothane anesthesia was observed in spontaneously ventilating beavers, but not in beavers maintained with controlled ventilation. All beavers recovered unremarkably from anesthesia. PMID:1906691

Greene, S A; Keegan, R D; Gallagher, L V; Alexander, J E; Harari, J

1991-05-01

314

Positional control of plasmonic fields and electron emission  

NASA Astrophysics Data System (ADS)

We report the positional control of plasmonic fields and electron emission in a continuous gap antenna structure of sub-micron size. We show experimentally that a nanoscale area of plasmon-enhanced electron emission can be motioned by changing the polarization of an exciting optical beam of 800 nm wavelength. Finite-difference calculations are presented to support the experiments and to show that the plasmon-enhanced electric field distribution of the antenna can be motioned precisely and predictively.

Word, R. C.; Fitzgerald, J. P. S.; Könenkamp, R.

2014-09-01

315

Emission control cost-effectiveness of alternative-fuel vehicles  

Microsoft Academic Search

Although various legislation and regulations have been adopted to promote the use of alternative-fuel vehicles for curbing urban air pollution problems, there is a lack of systematic comparisons of emission control cost-effectiveness among various alternative-fuel vehicle types. In this paper, life-cycle emission reductions and life-cycle costs were estimated for passenger cars fueled with methanol, ethanol, liquefied petroleum gas, compressed natural

Q. Wang; D. Sperling; J. Olmstead

1993-01-01

316

Acoustic emission feedback control for control of boiling in a microwave oven  

DOEpatents

An acoustic emission based feedback system for controlling the boiling level of a liquid medium in a microwave oven is provided. The acoustic emissions from the medium correlated with surface boiling is used to generate a feedback control signal proportional to the level of boiling of the medium. This signal is applied to a power controller to automatically and continuoulsly vary the power applied to the oven to control the boiling at a selected level.

White, Terry L. (Oak Ridge, TN)

1991-01-01

317

Effects of noradrenaline on consecutive vascular segments at low or normal calcium concentrations in control and spontaneously hypertensive rats.  

PubMed

1. An 'isogravimetric' technique, plus measurement of pressure in a small artery, was used to investigate the responses of upstream and downstream precapillary and postcapillary resistance vessels in the hindquarters of spontaneously hypertensive rats (SHR) and normal control rats perfused at constant flow. 2. Dose-response curves to noradrenaline were constructed under conditions of low or normal calcium. 3. In both control rats and SHR the dependence on external calcium during contraction increased peripherally, with the smaller pre- and post-capillary resistance vessels being most dependent and larger arteries least dependent. 4. There may be differences between SHR and control rats in regard to the handling of calcium, particularly in the small pre- and post-capillary resistance vessels. PMID:1071675

Folkow, B; Hallbäck, M; Jones, J V; Sutter, M

1976-12-01

318

Mercury emissions control technologies for mixed waste thermal treatment  

SciTech Connect

EPA has identified wet scrubbing at low mercury feedrates, as well as carbon adsorption via carbon injection into the offgas or via flow through fixed carbon beds, as control technologies that can be used to meet the proposed Maximum Achievable Control Technology (MACT) rule limit for mercury emissions from hazardous waste incinerators. DOE is currently funding demonstrations of gold amalgamation that may also control mercury to the desired levels. Performance data from a variety of sources was reviewed to determine ranges of achievable mercury control. Preliminary costs were estimated for using these technologies to control mercury emissions from mixed waste incineration. Mercury emissions control for mixed waste incineration may need to be more efficient than for incineration of other hazardous wastes because of higher mercury concentrations in some mixed waste streams. However, mercury control performance data for wet scrubbing and carbon adsorption is highly variable. More information is needed to demonstrate control efficiencies that are achievable under various design and operating conditions for wet scrubbing, carbon adsorption, and gold amalgamation technologies. Given certain assumptions made in this study, capital costs, operating costs, and lifecycle costs for carbon injection, carbon beds, and gold amalgamation generally vary for different assumed mercury feedrates and for different offgas flowrates. Assuming that these technologies can in fact provide the necessary mercury control performance, each of these technologies may be less costly than the others for certain mercury feedrates and the offgas flowrates.

Chambers, A.; Knecht, M.; Soelberg, N.; Eaton, D. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Roberts, D.; Broderick, T. [ADA Technologies, Englewood, CO (United States)

1997-12-31

319

The optimal time-window for surgical treatment of spontaneous intracerebral hemorrhage: result of prospective randomized controlled trial of 500 cases  

Microsoft Academic Search

The aim of this clinical study was to determine the optimal time-window for surgical treatment of spontaneous intracerebral\\u000a hemorrhage (ICH). From January 1998 to September 2000, 17 hospitals in Shanghai participated in a prospective randomized controlled\\u000a trial. Among a consecutive series of 500 patients with spontaneous ICH, 234 underwent medical treatment and 266 patients received\\u000a surgical treatment. According to the

Y. F. Wang; J. S. Wu; Y. Mao; X. C. Chen; L. F. Zhou; Y. Zhang

320

Spontaneous and induced sister chromatid exchanges and delayed cell proliferation in peripheral lymphocytes of Bowen's disease patients and matched controls of arseniasis-hyperendemic villages in Taiwan  

Microsoft Academic Search

A total of 15 newly-developed Bowen's disease patients and 34 age-sex-residence-matched controls were recruited from three arseniasis-hyperendemic villages in Taiwan to compare spontaneous and arsenic-induced sister chromatid exchanges (SCEs), proportion of cells with high frequencies of SCEs (HFCs), and replication index (RI) in their peripheral lymphocytes. Arsenic-induced Bowen's disease patients were found to have significantly higher spontaneous SCEs and HFCs

Yi-Hsiang Hsu; Shuan-Yow Li; Hung-Yi Chiou; Pi-Ming Yeh; Jung-Chin Liou; Yu-Mei Hsueh; Shu-Hui Chang; Chien-Jen Chen

1997-01-01

321

SO2 Emission Control: The Problem and Solutions  

NASA Astrophysics Data System (ADS)

In the past 10 years sulfur oxide emission control has been a key factor in the economic performance of many smelting operations, and markedly effects the choice of process and the design of new installations. This paper presents a review of pyrometallurgical processes for the production of copper, lead, and zinc. To put the problem in perspective, the review first outlines sulfur emission sources and alternate processing techniques, including oxygen enrichment and continuous and flash smelting. Alternate control systems, including sulfuric acid, liquid SO2, elemental sulfur, and weak gas scrubbing processes are then described from operational and economic standpoints.

Friedman, Leonard J.

1981-03-01

322

Neutron and Prompt Gamma Ray Emission in the Proton Induced Fission of 239Np and 243Am and Spontaneous Fission of 252Cf  

NASA Astrophysics Data System (ADS)

Average prescission < Mnpre > and postscission < Mnpost > neutron multiplicities as well as average ?-ray multiplicity , average energy emitted by ?-rays and average energy per one gamma quantum as a function of mass and total kinetic energy (TKE) of fission fragments were measured in proton induced reactions p+242Pu?243Am, p+238U?239Np (at proton energy Ep=13, 20 and 55 MeV) and spontaneous fission of 252Cf. The solid angle aberration and the Doppler shift in the laboratory angular distribution of ?-ray emission were utilized to obtain the number and energy of ?-rays as functions of single fragment mass. The results in the case of 252Cf, for both average number and average energy as functions of single fragment mass, are characterized by a sawtooth behavior similar to that which is well known for neutron emission. The similar behavior is seen for proton induced fission of 239Np and 243Am. The fragment mass dependence < Mnpost > (m) and (m) show a clear sawtooth structure that is gradually washed out with increasing proton energy Ep. Using the response matrix techniques we were able to distinguish between the statistical dipole (E1) and collective quadrupole (E2) ?-ray emission of single fission fragments.

Krupa, L.; Kniajeva, G. N.; Kliman, J.; Bogatchev, A. A.; Chubarian, G. M.; Dorvaux, O.; Itkis, I. M.; Itkis, M. G.; Khlebnikov, S.; Kondratiev, N. A.; Kozulin, E. M.; Lyapin, V.; Materna, T.; Rubchenia, W.; Pokrovsky, I. V.; Trzaska, W.; Vakhtin, D.; Voskressensky, V. M.

2005-09-01

323

The Effect of Static Ear Canal Pressure on Human Spontaneous Otoacoustic Emissions: Spectral Width as a Measure of the Intra-cochlear Oscillation Amplitude  

PubMed Central

Spontaneous otoacoustic emissions can be detected as peaks in the Fourier spectrum of a microphone signal recorded from the ear canal. The height, center frequency, and spectral width of SOAE peaks changed when a static pressure was applied to the ear canal. Most commonly, with either increasing or decreasing static pressure, the frequency increased, the amplitude decreased, and the width increased. These changes are believed to result from changes in the middle ear properties. Specifically, reduced middle ear transmission is assumed to attenuate the amplitude of emissions. We reconsidered this explanation by investigating the relation between peak height and width. We showed that the spectral width of SOAE peaks is approximately proportional to \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ 1/\\sqrt {{{\\hbox{peak}}\\;{\\hbox{height}}}} $$\\end{document}. This is consistent with a (Rayleigh) oscillator model in which broadening of the SOAE peak is caused by broadband intra-cochlear noise, which is assumed to be independent of static ear canal pressure. The relation between emission peak height and width implicates that the intra-cochlear oscillation amplitude attentuates relative to the intra-cochlear noise level when a static ear canal pressure is applied. Apparently, ear canal static pressure directly affects the active mechanics in the inner ear. PMID:21061039

Maat, Bert; de Kleine, Emile

2010-01-01

324

NOx Sensor for Direct Injection Emission Control  

SciTech Connect

The Electricore/Delphi team continues to leverage the electrochemical planar sensor technology that has produced stoichiometric planar and wide range oxygen sensors as the basis for development of a NOx sensor. Zirconia cell technology with an integrated heater will provide the foundation for the sensor structure. Proven materials and packaging technology will help to ensure a cost-effective approach to the manufacture of this sensor. The electronics technique and interface is considered to be an area where new strategies need to be employed to produce higher S/N ratios of the NOx signal with emphasis on signal stability over time for robustness and durability Both continuous mode and pulse mode control techniques are being evaluated. Packaging the electronics requires careful design and circuit partitioning so that only the necessary signal conditioning electronics are coupled directly in the wiring harness, while the remainder is situated within the ECM for durability and costs reasons. This task continues to be on hold due to the limitation that the definition of the interface electronics was unavailable until very late in the project. The sense element is based on the amperometric method utilizing integrated alumina and zirconia ceramics. Precious metal electrodes are used to form the integrated heater, the cell electrodes and leads. Inside the actual sense cell structure, it is first necessary to separate NOx from the remaining oxygen constituents of the exhaust, without reducing the NOx. Once separated, the NOx will be measured using a measurement cell. Development or test coupons have been used to facilitate material selection and refinement, cell, diffusion barrier, and chamber development. The sense element currently requires elaborate interconnections. To facilitate a robust durable connection, mechanical and metallurgical connections are under investigation. Materials and process refinements continue to play an important role in the development of the sensor.

Betteridge, William J

2006-02-28

325

Enhanced control of mercury emissions through modified speciation  

SciTech Connect

In anticipation of possible regulations regarding mercury emissions, research efforts sponsored by DOE, EPRI, and others are investigating the risks posed by mercury emissions, improved techniques for measuring those emissions, and possible control measures. The focus in the control research is on techniques that can be used in conjunction with existing flue-gas-cleanup (FGC) systems in order to minimize additional capital costs and operational complexity. Argonne National Laboratory has supported the DOE Fossil Energy Program for over 15 years with research on advanced environmental control technologies. The emphasis in Argonne`s work has been on integrated systems that combine control of several pollutants. Specific topics have included spray drying for sulfur dioxide and particulate-matter control with high-sulfur coal, combined sulfur dioxide and nitrogen oxides control technologies, and techniques to enhance mercury control in existing FGC systems. The latter area has focused on low-cost dry sorbents for use with fabric filters or electrostatic precipitators and techniques for improving the capture of mercury in wet flue-gas desulfurization (FGD) systems. This paper presents results from recent work that has studied the effects of several oxidizing agents in combination with typical flue-gas species (e.g., nitrogen oxides and sulfur dioxide) on the oxidation of Hg{sup 0}.

Livengood, C.D.; Mendelsohn, M.H.

1997-07-01

326

Raman-shifted KrF laser radiation with low amplified spontaneous emission for a rotational Raman daytime-temperature lidar.  

PubMed

Various configurations of a tunable two-stage KrF laser have been investigated for providing powerful laser pulses with very low amplified spontaneous emission (ASE). The lowest fraction (0.00017%) of ASE was attained with a single-pass amplifier and a phase-conjugate Brillouin mirror. The most suitable application envisaged for the laser source, i.e., remote daytime-temperature measurement by means of rotational Raman scattering, is a dedicated oscillator-amplifier configuration with an ASE of 0.005% at an output of 300 mJ. The very low values of ASE were measured with the aid of a thallium atomic-vapor filter. PMID:19844529

Luckow, F; Voss, E; Zeyn, J; Lahmann, W; Weitkamp, C; Michaelis, W

1994-07-15

327

Demonstration of high-power and stable C-band and L-band erbium-doped fiber amplified spontaneous emission sources using multipumping configuration  

NASA Astrophysics Data System (ADS)

We have investigated and experimentally demonstrated high-power and stable C-band and L-band erbium-doped fiber amplified spontaneous emission (ASE) sources using a multipumping configuration, which can provide an output power of 27.16 dBm (519.99 mW) and 27.34 dBm (542.01 mW) with a power ripple of 5.9 and 1.1 dB for C-band and L-band without adding any external spectra-flattening components. Moreover, the averaged power stability of C-band and L-band erbium-doped fiber ASE source with +/-0.005 and +/-0.003 dB during an 8-h interval measurements at the room temperature 25 °C can be achieved, allowing high pumping efficiency of 38.5 and 36.9%.

Chang, Chia-Hsiung; Liang, Tsair-Chun

2009-09-01

328

Comparative study of amplified spontaneous emission and short pre-pulse impacts onto fast electron generation at sub-relativistic femtosecond laser-plasma interaction  

NASA Astrophysics Data System (ADS)

This paper describes the study of hot electron generation under the action of intense (˜1018 W/cm2) femtosecond pulses onto the surface of a solid target, in the presence of a long pre-plasma, which varied with different spatial extents and densities. The corona was formed by pre-pulses with varied intensities and temporal profiles (amplified spontaneous emission (ASE) and short pre-pulses). The most efficient fast electron acceleration, to energies well beyond the ponderomotive potential, was observed if the ASE was able to form to the extent of ˜100 ?m a slightly undercritical plasma. Energy of accelerated electrons underwent further growth if the laser pulse duration increased from ˜45 to ˜350 fs at constant energy fluence. The experimental results were supported by numerical simulations using 3D3V Mandor PIC code.

Ivanov, K. A.; Shulyapov, S. A.; Ksenofontov, P. A.; Tsymbalov, I. N.; Volkov, R. V.; Savel'ev, A. B.; Brantov, A. V.; Bychenkov, V. Yu.; Turinge, A. A.; Lapik, A. M.; Rusakov, A. V.; Djilkibaev, R. M.; Nedorezov, V. G.

2014-09-01

329

Transform-Limited X-Ray Pulse Generation from a High Brightness Self-Amplified Spontaneous Emission Free-Electron Laser  

E-print Network

A method to achieve High-Brightness Self-Amplified Spontaneous Emission (HB-SASE) in the Free Electron Laser (FEL) is described. The method uses repeated non-equal electron beam delays to de-localise the collective FEL interaction and break the radiation coherence length dependence on the FEL cooperation length. The method requires no external seeding or photon optics and so is applicable at any wavelength or repetition rate. It is demonstrated using linear theory and numerical simulations that the radiation coherence length can be increased by approximately two orders of magnitude over SASE with a corresponding increase in spectral brightness. Examples are shown of HB-SASE generating transform-limited FEL pulses in the soft X-ray and near transform-limited pulses in the hard X-ray. Such pulses may greatly benefit existing applications and may also open up new areas of scientific research.

McNeil, B W J; Dunning, D J

2012-01-01

330

Quantum Optical Coherence: Applications in Photon Switching, Control of Spontaneous Emission and Atom Localization  

E-print Network

Quantum interference and coherence lead to many interesting phenomenon and applications in quantum optics. In this dissertation, we study the quantum coherent properties in the following systems and aspects. We first investigate the optical...

Yang, Shuai

2013-12-12

331

Inhibition, Enhancement, and Control of Spontaneous Emission in Photonic Nanowires Joel Bleuse,* Julien Claudon,  

E-print Network

, a SE inhibition factor of 16, equivalent to the one obtained in state-of-the-art photonic crystals the performance of optoelectronic devices, such as microlasers or single-photon sources [1]. A first route inhibition factor reported so far ($ 17) was measured in the more mature technology of 2D-photonic crystals

332

The Quantum Vacuum of Complex Media. A Unified Approach to the Dielectric Constant, the Spontaneous Emission and the Zero-Temperature Electromagnetic Pressure  

E-print Network

We study from a critical perspective several quantum-electrodynamic phenomena commonly related to vacuum electromagnetic (EM) fluctuations in complex media. We compute the resonance-shift, the spontaneous emission rate, the local density of states and the van-der-Waals-Casimir pressure in a dielectric medium using a microscopic diagrammatic approach. We find, in agreement with some recent works, that these effects cannot be attributed to variations on the energy of the EM vacuum but to variations of the dielectric self-energy. This energy is the result of the interaction of the bare polarizability of the dielectric constituents with the EM fluctuations of an actually polarized vacuum. We have found an exact expression for the spectrum of these fluctuations in a statistically homogeneous dielectric. Those fluctuations turn out to be different to the ones of normal radiative modes. It is the latter that carry the zero-point-energy (ZPE). Concerning spontaneous emission, we clarify the nature of the radiation and the origin of the so-called local field factors. Essential discrepancies are found with respect to previous works. We perform a detailed analysis of the phenomenon of radiative and non-radiative energy transfer. Analytical formulae are given for the decay rate of an interstitial impurity in a Maxwell-Garnett dielectric and for the decay rate of a substantial impurity sited in a large cavity. The construction of the effective dielectric constant is found to be a self-consistency problem. The van-der-Waals pressure in a complex medium is computed in terms of variations of the dielectric self-energy at zero-temperature. An additional radiative pressure appears associated to variations of the EM vacuum energy.

M. Donaire

2009-12-16

333

Gamma Ray Multiplicity Comparison of a 2-Neutron and a 4-Neutron Emission ^252Cf Spontaneous Fission  

NASA Astrophysics Data System (ADS)

The correlation between ?-ray multiplicity and neutron multiplicity in the fission process is not currently well known. Competing theories predict opposite correlations and experiments have measured only average properties. We have measured the ?-ray multiplicity spectrum of ^252Cf spontaneous fission using the LiBerACE array, comprised of six high-purity germanium (HPGe) Clover detectors, each surrounded by 16 bismuth-germanate (BGO) detectors. The Clovers were arranged in a cubic pattern around a 1 ?Ci ^252Cf source. Neutron multiplicity was determined for two cases by identifying known correlated fission products from prompt ?-rays observed in the HPGe detectors. No difference in the ?-ray multiplicity spectrum was observed for fissions that produced ^106Mo/^144Ba (2 neutrons) compared to those producing ^106Mo/^142Ba (4 neutrons).

Bleuel, D. L.; Bernstein, L. A.; Burke, J. T.; Heffner, M. D.; Norman, E. B.; Scielzo, N. D.; Sheets, S. A.; Snyderman, N. J.; Stoyer, M. A.; Wiedeking, M.; Gibelin, J.; Phair, L. W.; Mintz, J.

2008-10-01

334

SPRAY CHARGING AND TRAPPING SCRUBBER FOR FUGITIVE PARTICLE EMISSION CONTROL  

EPA Science Inventory

The report gives results of a theoretical and experimental evaluation of the control of fugitive particle emissions (FPE) with a Spray Charging and Trapping (SCAT) Scrubber that uses an air curtain and/or jets to contain, convey, and divert the FPE into a charged spray scrubber. ...

335

LQG control for minimization of emissions in a diesel engine  

Microsoft Academic Search

The problem of minimizing emissions of NOx and soot in a diesel engine using fuel injection timings and exhaust gas recirculation (EGR) valve position in a low-pressure EGR system as control variables is addressed. Two feedback variables are computed from in-cylinder pressure sensor data, the crank angle degree of 50% fuel burnt, and the ignition delay. Empirical maps of NOx

Maria Karlsson; Kent Ekholm; Petter Strandh; Rolf Johansson; P. Tunestal

2008-01-01

336

PHYSICAL COAL CLEANING FOR UTILITY BOILER SO2 EMISSION CONTROL  

EPA Science Inventory

The report examines physical coal cleaning as a control technique for sulfur oxides emissions. It includes an analysis of the availability of low-sulfur coal and of coal cleanable to compliance levels for alternate New Source Performance Standards (NSPS). Various alternatives to ...

337

Implementing Strategies for Drying and Pressing Wood Without Emissions Controls  

Microsoft Academic Search

Drying and pressing wood for the manufacture of lumber, particleboard, oriented strand board (OSB), veneer and medium density fiberboard (MDF) release volatile organic compounds (VOCs) into the atmosphere. These emissions require control equipment that are capital-intensive and consume significant quantities of natural gas and electricity. The objective of our work was to understand the mechanisms through which volatile organic compounds

Sujit Banerjee; Terrance Conners

2007-01-01

338

Integrated transportation and energy sector CO 2 emission control strategies  

Microsoft Academic Search

This paper analyses the mutual benefits of integrating strategies for future energy and transport CO2 emissions control. The paper illustrates and quantifies the mutual benefits of integrating the transport and the energy sector in the case of Denmark. Today this issue is very relevant in Denmark due to the high share of fluctuating renewable energy produced in the country. In

Henrik Lund; Ebbe Münster

2006-01-01

339

ASSESSMENT OF THE USE OF FUGITIVE EMISSION CONTROL DEVICES  

EPA Science Inventory

The report compares the efficiencies and utility consumptions expected from three fugitive emission control techniques--building evacuation, charged fog sprays, and water sprays with additives--if they were applied in primary lead and copper smelters. Estimates are provided of th...

340

Blast Furnace Casthouse Control Technology and Recent Emissions Test Data  

Microsoft Academic Search

By the fall of 1980, three new and seven retrofit casthouse emission control systems had been installed in North America. A number of prototype systems are being evaluated by steel companies and regulatory agencies. By 1981, the U.S. steel industry had made commitments to install controls on at least 58 additional casthouses in the U.S.This paper describes the current status

Peter D. Spawn; Thomas J. Maslany

1981-01-01

341

Cardiovascular control in the Milan strain of spontaneously hypertensive rat (MHS) at "rest" and during acute mental "stress".  

PubMed

The cardiovascular responses to acute mental "stress" were compared in the Milan strain of spontaneously hypertensive rats (MHS) and in normotensive control rats (NR). Blood pressure and heart rate were followed in pairs of awake MHS and NR, while defence reactions were provoked by alerting stimuli (noise, vibration). No differences were noted between the two groups in response to "stress" although resting heart rate in MHS was lower than in NR. Administration of atropine or propranolol to MHS and NR showed the MHS to have a higher resting vagal tone and lower sympathetic tone than the NR. Subsequent (at least two weeks later) hemodynamic investigation, under nembutal anesthesia, showed no difference in cardiac output between MHS and NR but a higher stroke volume, presumably related to the lower heart rate in MHS. Thus, total peripheral resistance was increased in MHS as was the ratio left ventricular weight/body weight, and in good proportion to the blood pressure rise. Thus MHS differ substantially in both their responses to "stress" and also hemodynamically from the Okamoto strain of spontaneously hypertensive rat (SHR), being the so far most studied and best known model of essential hypertension in man. In MHS the hypertension is more of a systolic type and is of primarily renal origin. As such, MHS provide another model for investigating the polygenic nature of hypertension in man. PMID:557279

Hallbäck, M; Jones, J V; Bianchi, G; Folkow, B

1977-02-01

342

Cloning of genes from mucoid Pseudomonas aeruginosa which control spontaneous conversion to the alginate production phenotype.  

PubMed Central

Strains of Pseudomonas aeruginosa causing chronic pulmonary infections in patients with cystic fibrosis are known to convert to a mucoid form in vivo characterized by the production of the exopolysaccharide alginate. The alginate production trait is not stable, and mucoid strains frequently convert back to the nonmucoid form in vitro. The DNA involved in these spontaneous alginate conversions, referred to as algS, was shown here to map near hisI and pru markers on the chromosome of strain FRD, an isolate from a cystic fibrosis patient. Although cloning algS+ by trans-complementation was not possible, a clone (pJF5) was isolated that caused algS mutants to convert to the Alg+ phenotype at detectable frequencies (approximately 0.1%) in vitro. Gene replacement with transposon-marked pJF5 followed by mapping studies showed that pJF5 contained DNA transducibly close to algS in the chromosome. Another clone was identified called pJF15 which did contain algS+ from mucoid P. aeruginosa. The plasmid-borne algS+ locus could not complement spontaneous algS mutations in trans, but its cis-acting activity was readily observed after gene replacement with the algS mutant chromosome by using an adjacent transposon as the selectable marker. pJF15 also contained a trans-active gene called algT+ in addition to the cis-active gene algS+. The algT gene was localized on pJF15 by using deletion mapping and transposon mutagenesis. By using gene replacement, algT::Tn501 mutants of P. aeruginosa were constructed which were shown to be complemented in trans by pJF15. Both algS and algT were located on a DNA fragment approximately 3 kilobases in size. The algS gene may be a genetic switch which regulates the process of alginate conversion. PMID:2965141

Flynn, J L; Ohman, D E

1988-01-01

343

Biofiltration: an innovative air pollution control technology for VOC emissions.  

PubMed

Biofiltration is a relatively recent air pollution control (APC) technology in which off-gases containing biodegradable volatile organic compounds (VOC) or inorganic air toxics are vented through a biologically active material. This technology has been successfully applied in Germany and The Netherlands in many full-scale applications to control odors, VOC and air toxic emissions from a wide range of industrial and public sector sources. Control efficiencies of more than 90 percent have been achieved for many common air pollutants. Due to lower operating costs, biofiltration can provide significant economic advantages over other APC technologies if applied to off-gases that contain readily biodegradable pollutants in low concentrations. Environmental benefits include low energy requirements and the avoidance of cross media transfer of pollutants. This paper reviews the history and current status of biofiltration, outlines its underlying scientific and engineering principles, and discusses the applicability of biofilters for a wide range of specific emission sources. PMID:1958341

Leson, G; Winer, A M

1991-08-01

344

EGR-VGT Control and Tuning for Pumping Work Minimization and Emission Control  

Microsoft Academic Search

A control structure is proposed and investigated for coordinated control of exhaust gas recirculation (EGR) valve and variable geometry turbochargers (VGT) position in heavy duty diesel engines. Main control goals are to fulfill the legislated emission levels, to reduce the fuel consumption, and to fulfill safe operation of the turbocharger. These goals are achieved through regulation of normalized oxygen\\/fuel ratio,

Johan Wahlstrom; Lars Eriksson; Lars Nielsen

2010-01-01

345

Dual-Band Plasmonic Enhancement of Ag-NS@SiO 2 on Gain Medium’s Spontaneous Emission  

Microsoft Academic Search

We present a theoretical study on plasmonic enhancement of molecular fluorescence near a nanocomposite, Ag nanoshell (Ag-NS)\\u000a coated by a gain medium of molecule-doped SiO2 layer. We use an average enhancement factor (AEF), which considers contributions from all possible orientations and locations\\u000a of molecules in the silica layer to estimate the overall performance of Ag-NS@SiO2 at specific excitation and emission

Jiunn-Woei Liaw; Chuan-Li Liu; Mao-Kuen Kuo

346

LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL  

SciTech Connect

''Conventional'' waste landfills emit methane, a potent greenhouse gas, in quantities such that landfill methane is a major factor in global climate change. Controlled landfilling is a novel approach to manage landfills for rapid completion of total gas generation, maximizing gas capture and minimizing emissions of methane to the atmosphere. With controlled landfilling, methane generation is accelerated and brought to much earlier completion by improving conditions for biological processes (principally moisture levels) in the landfill. Gas recovery efficiency approaches 100% through use of surface membrane cover over porous gas recovery layers operated at slight vacuum. A field demonstration project's results at the Yolo County Central Landfill near Davis, California are, to date, highly encouraging. Two major controlled landfilling benefits would be the reduction of landfill methane emissions to minuscule levels, and the recovery of greater amounts of landfill methane energy in much shorter times than with conventional landfill practice. With the large amount of US landfill methane generated, and greenhouse potency of methane, better landfill methane control can play a substantial role in reduction of US greenhouse gas emissions.

Don Augenstein

1999-01-11

347

Control of Several Emissions during Olive Pomace Thermal Degradation.  

PubMed

Biomass plays an important role as an energy source, being an interesting alternative to fossil fuels due to its environment-friendly and sustainable characteristics. However, due to the exposure of customers to emissions during biomass heating, evolved pollutants should be taken into account and controlled. Changing raw materials or mixing them with another less pollutant biomass could be a suitable step to reduce pollution. This work studied the thermal behaviour of olive pomace, pyrenean oak and their blends under combustion using thermogravimetric analysis. It was possible to monitor the emissions released during the process by coupling mass spectrometry analysis. The experiments were carried out under non-isothermal conditions at the temperature range 25-750 °C and a heating rate of 20 °C·min-1. The following species were analysed: aromatic compounds (benzene and toluene), sulphur emissions (sulphur dioxide), 1,4-dioxin, hydrochloric acid, carbon dioxide and nitrogen oxides. The results indicated that pollutants were mainly evolved in two different stages, which are related to the thermal degradation steps. Thus, depending on the pollutant and raw material composition, different emission profiles were observed. Furthermore, intensity of the emission profiles was related, in some cases, to the composition of the precursor. PMID:25314298

Miranda, Teresa; Nogales, Sergio; Román, Silvia; Montero, Irene; Arranz, José Ignacio; Sepúlveda, Francisco José

2014-01-01

348

Control of Several Emissions during Olive Pomace Thermal Degradation  

PubMed Central

Biomass plays an important role as an energy source, being an interesting alternative to fossil fuels due to its environment-friendly and sustainable characteristics. However, due to the exposure of customers to emissions during biomass heating, evolved pollutants should be taken into account and controlled. Changing raw materials or mixing them with another less pollutant biomass could be a suitable step to reduce pollution. This work studied the thermal behaviour of olive pomace, pyrenean oak and their blends under combustion using thermogravimetric analysis. It was possible to monitor the emissions released during the process by coupling mass spectrometry analysis. The experiments were carried out under non-isothermal conditions at the temperature range 25–750 °C and a heating rate of 20 °C·min?1. The following species were analysed: aromatic compounds (benzene and toluene), sulphur emissions (sulphur dioxide), 1,4-dioxin, hydrochloric acid, carbon dioxide and nitrogen oxides. The results indicated that pollutants were mainly evolved in two different stages, which are related to the thermal degradation steps. Thus, depending on the pollutant and raw material composition, different emission profiles were observed. Furthermore, intensity of the emission profiles was related, in some cases, to the composition of the precursor. PMID:25314298

Miranda, Teresa; Nogales, Sergio; Román, Silvia; Montero, Irene; Arranz, José Ignacio; Sepúlveda, Francisco José

2014-01-01

349

Emissions from premixed charge compression ignition (PCCI) combustion and affect on emission control devices  

SciTech Connect

A light-duty diesel engine has been operated in advanced combustion modes known generally as premixed charge compression ignition (PCCI). The emissions have been characterized for several load and speed combinations. Fewer NO{sub x} and particulate matter (PM) emissions are produced by PCCI, but higher CO and hydrocarbon (HC) emissions result. In addition, the nature of the PM differs from conventional combustion; the PM is smaller and has a much higher soluble organic fraction (SOF) content (68% vs. 30% for conventional combustion). Three catalyst technologies were studied to determine the affects of HECC on catalyst performance; the technologies were a lean NO{sub x} trap (LNT), diesel oxidation catalyst (DOC), and diesel particulate filter (DPF). The LNT benefited greatly from the reduced NO{sub x} emissions associated with PCCI. NO{sub x} capacity requirements are reduced as well as overall tailpipe NO{sub x} levels particularly at low load and temperature conditions where regeneration of the LNT is difficult. The DOC performance requirements for PCCI are more stringent due to the higher CO and HC emissions; however, the DOC was effective at controlling the higher CO and HC emissions at conditions above the light-off temperature. Below light-off, CO and HC emissions are problematic. The study of DPF technology focused on the fuel penalties associated with DPF regeneration or 'desoot' due to the different PM loading rates from PCCI vs. conventional combustion. Less frequent desoot events were required from the lower PM from PCCI and, when used in conjunction with an LNT, the lower PM from less frequent LNT regeneration. The lower desoot frequency leads a {approx}3% fuel penalty for a mixture of PCCI and conventional loads vs. {approx}4% for conventional only combustion.

Parks, II, James E [ORNL; Kass, Michael D [ORNL] [ORNL; Huff, Shean P [ORNL] [ORNL; Barone, Teresa L [ORNL] [ORNL; Lewis Sr, Samuel Arthur [ORNL] [ORNL; Prikhodko, Vitaly Y [ORNL] [ORNL; Storey, John Morse [ORNL] [ORNL

2010-01-01

350

Laser Emission Control by Means of Resonant Gratings  

NASA Astrophysics Data System (ADS)

New diffractive optical elements of the resonant type result from the association of a surface corrugation with an optical resonator in the form of a slab waveguide whose surface is corrugated or whose refractive index is periodically modulated. As a result, the resonant corrugation diffracts an incident free space wave more efficiently than a conventional corrugation and, more importantly, exhibits selectivity features in angle, wavelength and polarization which can be used for the control of laser emission. A practically attractive characteristic of such elements is that they are planar, therefore they can be associated monolithically with the laser mirror, and can be fabricated by low-cost and highly reproducible batch planar microstructuring technologies. The characteristics of laser emission which can be controlled are the emission wavelength(s), the polarization and the polarization distribution over the beam cross-section, and even the transverse mode content (i.e., the spatial coherence of the emitted beam). The paper describes the modal electromagnetic mechanisms which can be used to improve laser emission, and will give examples of lasers such as microchip, high power Nd: and Yb:YAG, and CO2 lasers.

Tonchev, S.; Tishchenko, A. V.; Parriaux, O.

2010-01-01

351

The effects of energy paths and emission controls and standards on future trends in China's emissions of primary air pollutants  

NASA Astrophysics Data System (ADS)

To examine the efficacy of China's actions to control atmospheric pollution, three levels of growth of energy consumption and three levels of implementation of emission controls are estimated, generating a total of nine combined activity-emission control scenarios that are then used to estimate trends of national emissions of primary air pollutants through 2030. The emission control strategies are expected to have more effects than the energy paths on the future emission trends for all the concerned pollutants. As recently promulgated national action plans of air pollution prevention and control (NAPAPPC) are implemented, China's anthropogenic pollutant emissions should decline. For example, the emissions of SO2, NOx, total suspended particles (TSP), PM10, and PM2.5 are estimated to decline 7, 20, 41, 34, and 31% from 2010 to 2030, respectively, in the "best guess" scenario that includes national commitment of energy saving policy and implementation of NAPAPPC. Should the issued/proposed emission standards be fully achieved, a less likely scenario, annual emissions would be further reduced, ranging from 17 (for primary PM2.5) to 29% (for NOx) declines in 2015, and the analogue numbers would be 12 and 24% in 2030. The uncertainties of emission projections result mainly from the uncertain operational conditions of swiftly proliferating air pollutant control devices and lack of detailed information about emission control plans by region. The predicted emission trends by sector and chemical species raise concerns about current pollution control strategies: the potential for emissions abatement in key sectors may be declining due to the near saturation of emission control devices use; risks of ecosystem acidification could rise because emissions of alkaline base cations may be declining faster than those of SO2; and radiative forcing could rise because emissions of positive-forcing carbonaceous aerosols may decline more slowly than those of SO2 emissions and thereby concentrations of negative-forcing sulfate particles. Expanded control of emissions of fine particles and carbonaceous aerosols from small industrial and residential sources is recommended, and a more comprehensive emission control strategy targeting a wider range of pollutants (volatile organic compounds, NH3 and CO, etc.) and taking account of more diverse environmental impacts is also urgently needed.

Zhao, Y.; Zhang, J.; Nielsen, C. P.

2014-09-01

352

Spontaneous photon-emission from a non-relativistic free charged particle in collapse models: A case-study  

E-print Network

We study the photon emission rate of a non relativistic charged particle interacting with an external classical noise through its position. Both the particle and the electromagnetic field are quantized. Under only the dipole approximation, the equations of motion can be solved exactly for a free particle, or a particle bounded by an harmonic potential. The physical quantity we will be interested in is the spectrum of the radiation emitted by the particle, due to the interaction with the noise. We will highlight several properties of the spectrum and clarify some issues appeared in the literature, regarding the exact mathematical formula of a spectrum for a free particle.

Angelo Bassi; Sandro Donadi

2013-07-01

353

Controlling light-emission properties of power scalable fiber lasers  

Microsoft Academic Search

We present several methods controlling light-emission properties in power-scalable fiber lasers, including modal quality, polarization, spectra, and optical nonlinearities. The thesis contains three major parts. In the first part we present high power fiber lasers and high energy fiber amplifiers based on LMA fibers, which need external mode management techniques to maintain diffraction-limited output quality. The 810W high power CW

Chi-Hung Liu

2007-01-01

354

Presence of Antibodies Against Coxiella burnetii and Risk of Spontaneous Abortion: A Nested Case-Control Study  

PubMed Central

Background and Aims Q fever is a bacterial zoonosis caused by infection with Coxiella burnetii. It is well established that Q fever causes fetal loss in small ruminants. The suspicion has been raised that pregnant women may also experience adverse pregnancy outcome when the infection is acquired or reactivated during pregnancy. The purpose of this study was to assess the potential association between serologic markers of infection with C.burnetii and spontaneous abortion. Methods A nested case-control study within the Danish National Birth Cohort, a cohort of 100,418 pregnancies recruited from 1996–2002. Women were recruited in first trimester of pregnancy and followed prospectively. Median gestational age at enrolment was 8 weeks (25 and 75 percentiles: 7 weeks; 10 weeks). During pregnancy, a blood sample was collected at gestational week 6–12 and stored in a bio bank. For this study, a case sample of 218 pregnancies was drawn randomly among the pregnancies in the cohort which ended with a miscarriage before 22 gestational weeks, and a reference group of 482 pregnancies was selected in a random fashion among all pregnancies in the cohort. From these pregnancies, serum samples were screened for antibodies against C. burnetii in a commercial enzyme-linked immunosorbent assay (ELISA). Samples that proved IgG or IgM antibody positive were subsequently confirmatory tested by an immunofluorescence (IFA) test. Results Among cases, 11 (5%) were C. burnetii positive in ELISA of which one was confirmed in the IFA assay compared to 29 (6%) ELISA positive and 3 IFA confirmed in the random sample. Conclusions We found no evidence of a higher prevalence of C.burnetii antibodies in serum samples from women who later miscarried and the present study does not indicate a major association between Q fever infection and spontaneous abortion in humans. Very early first trimester abortions were, however, not included in the study. PMID:22363769

Nielsen, Stine Yde; Hjøllund, Niels Henrik; Andersen, Anne-Marie Nybo; Henriksen, Tine Brink; Kantsø, Bjørn; Krogfelt, Karen Angeliki; Mølbak, Kåre

2012-01-01

355

Spontaneous abortion.  

PubMed

Sporadic spontaneous abortion has been accorded relatively little scientific attention but has widespread prevalence and great personal impact. The physician must be continually vigilant to consider possibilities for Rh0(D) sensitization and offer prophylaxis when appropriate. The most immediate problems include differential diagnosis, haemorrhage, and infection, while later issues focus on counselling and subsequent pregnancies. Serious physical and psychological morbidity can be averted by the conscientious care of couples experiencing spontaneous pregnancy loss. PMID:3086012

Laferla, J J

1986-03-01

356

Dopamine and Cognitive Control: The Influence of Spontaneous Eyeblink Rate and Dopamine Gene Polymorphisms on Perseveration  

E-print Network

Polymorphisms on Perseveration and Distractibility Gesine Dreisbach, Johannes Mu¨ller, Thomas Goschke from perseveration and behavioral rigidity (see Goschke, 2003, for a discussion of these control. In this so-called perseveration condition, increased flexibility should facilitate the disengagement from

Schubart, Christoph

357

COMBUSTION CONTROL OF PCDD/PCDF EMISSIONS FROM MUNICIPAL WASTE INCINERATORS IN NORTH AMERICA  

EPA Science Inventory

The paper discusses combustion control of emissions of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) from municipal waste incinerators in North America. New regulations to control air pollution emissions from municipal waste incineration have b...

358

40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false What permeation emission control requirements apply...Related Requirements § 1060.103 What permeation emission control requirements apply...tanks? (a) Fuel tanks must meet permeation requirements as follows:...

2013-07-01

359

40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false What permeation emission control requirements apply...Related Requirements § 1060.102 What permeation emission control requirements apply... (a) Nonmetal fuel lines must meet permeation requirements as follows:...

2013-07-01

360

40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false What permeation emission control requirements apply...Related Requirements § 1060.103 What permeation emission control requirements apply...tanks? (a) Fuel tanks must meet permeation requirements as follows:...

2012-07-01

361

40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false What permeation emission control requirements apply...Related Requirements § 1060.102 What permeation emission control requirements apply... (a) Nonmetal fuel lines must meet permeation requirements as follows:...

2010-07-01

362

40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false What permeation emission control requirements apply...Related Requirements § 1060.102 What permeation emission control requirements apply... (a) Nonmetal fuel lines must meet permeation requirements as follows:...

2012-07-01

363

40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false What permeation emission control requirements apply...Related Requirements § 1060.103 What permeation emission control requirements apply...tanks? (a) Fuel tanks must meet permeation requirements as follows:...

2010-07-01

364

40 CFR 1060.102 - What permeation emission control requirements apply for fuel lines?  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false What permeation emission control requirements apply...Related Requirements § 1060.102 What permeation emission control requirements apply... (a) Nonmetal fuel lines must meet permeation requirements as follows:...

2011-07-01

365

40 CFR 1060.103 - What permeation emission control requirements apply for fuel tanks?  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false What permeation emission control requirements apply...Related Requirements § 1060.103 What permeation emission control requirements apply...tanks? (a) Fuel tanks must meet permeation requirements as follows:...

2011-07-01

366

Technology for CO{sub 2} emission monitoring and control  

SciTech Connect

The authors examined three specific areas relative to CO{sub 2} emissions and controls: (1) the effect of deregulation of the utility industry on emissions, (2) the role of advanced power systems in reducing emissions, and (3) developing CO{sub 2} mitigation technologies. In this work the Energy Technologies program office at Los Alamos attempted to initiate an integrated approach that includes a range of tasks involving both point and distributed CO{sub 2} control. The authors have examined evolving mitigation (separation and sequestration) technologies for CO{sub 2} disposal. The separation of hydrogen gas from high-temperature CO{sub 2}-containing streams is a critical component of carbon dioxide mitigation technology, and cost-effective point sequestration will require separation of CO{sub 2} from H{sub 2}. They investigated four types of separation techniques: two high-temperature membrane technologies, an intermediate-temperature membrane technology, and a separation technology based on the formation of CO{sub 2} hydrate compounds through reaction of CO{sub 2} with water at near freezing conditions. At Los Alamos, sequestration technologies are being developed along three principal areas: mineral sequestration of CO{sub 2}, the enhancement of natural sinks using biotechnology methods, and the conversion of CO{sub 2} to methanol using high-temperature photolysis.

Joyce, E.L. Jr.; Unkefer, P.J.; Pendergrass, J.H.; Parkinson, W.J.; Loose, V.W.; Brainard, J.R.

1998-12-31

367

Active Control of Combustor Instability Shown to Help Lower Emissions  

NASA Technical Reports Server (NTRS)

In a quest to reduce the environmental impact of aerospace propulsion systems, extensive research is being done in the development of lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle. However, these lean-burning combustors have an increased susceptibility to thermoacoustic instabilities, or high-pressure oscillations much like sound waves, that can cause severe high-frequency vibrations in the combustor. These pressure waves can fatigue the combustor components and even the downstream turbine blades. This can significantly decrease the safe operating life of the combustor and turbine. Thus, suppression of the thermoacoustic combustor instabilities is an enabling technology for lean, low-emissions combustors. Under the Aerospace Propulsion and Power Base Research and Technology Program, the NASA Glenn Research Center, in partnership with Pratt & Whitney and United Technologies Research Center, is developing technologies for the active control of combustion instabilities. With active combustion control, the fuel is pulsed to put pressure oscillations into the system. This cancels out the pressure oscillations being produced by the instabilities. Thus, the engine can have lower pollutant emissions and long life.The use of active combustion instability control to reduce thermo-acoustic-driven combustor pressure oscillations was demonstrated on a single-nozzle combustor rig at United Technologies. This rig has many of the complexities of a real engine combustor (i.e., an actual fuel nozzle and swirler, dilution cooling, etc.). Control was demonstrated through modeling, developing, and testing a fuel-delivery system able to the 280-Hz instability frequency. The preceding figure shows the capability of this system to provide high-frequency fuel modulations. Because of the high-shear contrarotating airflow in the fuel injector, there was some concern that the fuel pulses would be attenuated to the point where they would not be effective for control. Testing in the combustor rig showed that open-loop pulsing of the fuel was, in fact, able to effectively modulate the combustor pressure. To suppress the combustor pressure oscillations due to thermoacoustic instabilities, it is desirable to time the injection of the fuel so that it interferes with the instability. A closed-loop control scheme was developed that uses combustion pressure feedback and a phase-shifting controller to time the fuel-injection pulses. Some suppression of the pressure oscillations at the 280-Hz instability frequency was demonstrated (see the next figure). However, the overall peak-to- peak pressure oscillations in the combustor were only mildly reduced. Improvements to control hardware and control methods are being continued to gain improved closed-loop reduction of the pressure oscillations.pulse the fuel at

DeLaat, John C.; Chang, Clarence T.

2002-01-01

368

Dopamine and inhibitory action control: evidence from spontaneous eye blink rates  

Microsoft Academic Search

The inhibitory control of actions has been claimed to rely on dopaminergic pathways. Given that this hypothesis is mainly\\u000a based on patient and drug studies, some authors have questioned its validity and suggested that beneficial effects of dopaminergic\\u000a stimulants on response inhibition may be limited to cases of suboptimal inhibitory functioning. We present evidence that,\\u000a in carefully selected healthy adults,

Lorenza Serena Colzato; Wery P. M. van den Wildenberg; Nelleke C. van Wouwe; Merel M. Pannebakker; Bernhard Hommel

2009-01-01

369

40 CFR 65.145 - Nonflare control devices used to control emissions from storage vessels or low-throughput...  

...control devices used to control emissions from storage...AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Closed Vent Systems, Control Devices, and Routing...control device, including flow and regulated...

2014-07-01

370

Propagation of a strong x-ray pulse: Pulse compression, stimulated Raman scattering, amplified spontaneous emission, lasing without inversion, and four-wave mixing  

SciTech Connect

We study the compression of strong x-ray pulses from x-ray free-electron lasers (XFELs) propagating through the resonant medium of atomic argon. The simulations are based on the three-level model with the frequency of the incident x-ray pulse tuned in the 2p{sub 3/2}-4s resonance. The pulse propagation is accompanied by the self-seeded stimulated resonant Raman scattering (SRRS). The SRRS starts from two channels of amplified spontaneous emission (ASE), 4s-2p{sub 3/2} and 3s-2p{sub 3/2}, which form the extensive ringing pattern and widen the power spectrum. The produced seed field triggers the Stokes ASE channel 3s-2p{sub 3/2}. The population inversion is quenched for longer propagation distances where the ASE is followed by the lasing without inversion (LWI), which amplifies the Stokes component. Both ASE and LWI reshape the input pulse: The compressed front part of the pulse (up to 100 as) is followed by the long tail of the ringing and beating between the pump and Stokes frequencies. The pump pulse also generates weaker Stokes and anti-Stokes fields caused by four-wave mixing. These four spectral bands have fine structures caused by the dynamical Stark effect. A slowdown of the XFEL pulse up to 78% of the speed of light in vacuum is found because of a large nonlinear refractive index.

Sun Yuping; Wang Chuankui [College of Physics and Electronics, Shandong Normal University, 250014 Jinan (China); Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, S-10691 Stockholm (Sweden); Liu Jicai; Gel'mukhanov, Faris [Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, S-10691 Stockholm (Sweden)

2010-01-15

371

Natural emissions for regional modeling of background ozone and particulate matter and impacts on emissions control strategies  

NASA Astrophysics Data System (ADS)

Natural emissions adopted in current regional air quality modeling are updated to better describe natural background ozone and PM concentrations for North America. The revised natural emissions include organosulfur from the ocean, NO from lightning, sea salt, biogenic secondary organic aerosol (SOA) precursors, and pre-industrial levels of background methane. The model algorithm for SOA formation was also revised. Natural background ozone concentrations increase by up to 4 ppb in annual average over the southeastern US and Gulf of Mexico due to added NO from lightning while the revised biogenic emissions produced less ozone in the central and western US. Natural PM 2.5 concentrations generally increased with the revised natural emissions. Future year (2018) simulations were conducted for several anthropogenic emission reduction scenarios to assess the impact of the revised natural emissions on anthropogenic emission control strategies. Overall, the revised natural emissions did not significantly alter the ozone responses to the emissions reductions in 2018. With revised natural emissions, ozone concentrations were slightly less sensitive to reducing NOx in the southeastern US than with the current natural emissions due to higher NO from lightning. The revised natural emissions have little impact on modeled PM 2.5 responses to anthropogenic emission reductions. However, there are substantial uncertainties in current representations of natural sources in air quality models and we recommend that further study is needed to refine these representations.

Koo, Bonyoung; Chien, Chao-Jung; Tonnesen, Gail; Morris, Ralph; Johnson, Jeremiah; Sakulyanontvittaya, Tanarit; Piyachaturawat, Piti; Yarwood, Greg

2010-06-01

372

Spontaneous acromegaly: A retrospective case control study in German shepherd dogs.  

PubMed

Acromegaly results from the overproduction of growth hormone in adulthood and is characterised by overgrowth of soft tissue and/or bone as well as insulin resistance. There are few data indicating the risk factors associated with this disease in dogs or its clinicopathological features and sequelae. The objective of this retrospective study was to catalogue and assess these aspects of the disease in German shepherd dogs (GSDs) which were found to be over-represented among acromegalic dogs attending two veterinary referral clinics over a period of 7?years. Each acromegalic dog (AD) was compared with two breed/age/sex matched controls. Clinical signs of acromegaly included panting, polyuria/polydipsia, widened interdental spaces, weakness, inspiratory stridor, macroglossia, weight gain, redundant skin folds, thick coat, exophthalmos and mammary masses. Serum alkaline phosphatase, creatine-kinase, glucose, triglyceride, phosphate ion, and 'calcium per phosphate product' concentrations were significantly higher in acromegalic animals while haemoglobin concentration, blood urea nitrogen, sodium and chloride ion concentrations, and urinary specific gravity, osmolality and fractional excretion of phosphate were significantly lower. Although, in the majority of cases clinicopathological abnormalities resolved following ovariohysterectomy, in one dog, acromegalic signs abated and insulin-like growth factor-1 concentrations normalised only following the surgical excision of mammary tumours carried out 2?months after ovariohysterectomy. The findings of this study indicate that GSDs are predisposed to the development of acromegaly with a suspected inherited susceptibility. PMID:24986315

Fracassi, F; Zagnoli, L; Rosenberg, D; Furlanello, T; Caldin, M

2014-10-01

373

Jovian longitudinal control of Io-related radio emissions  

NASA Technical Reports Server (NTRS)

A theoretical model is proposed to explain the control of Io-related radio emissions by Jupiter's rotational phase. The model is based on the hypothesis that the radio emissions are generated by Birkeland currents flowing between Io and the Jovian ionosphere. Specifically, it is suggested that the precipitation of radiation-belt electrons within a certain range of Jovian longitudes produces a restricted region of enhanced ionization and correspondingly enhanced conductivity in Jupiter's ionosphere and that the Io-Jupiter Birkeland current and the associated radio emissions are dramatically increased when Io's flux tube encounters this sector of enhanced ionization in Jupiter's ionosphere. The magnitude of the current is found to be about 100,000 A at most Jovian longitudes because of ionospheric resistance. It is estimated that within the favored longitudinal sector electron precipitation produces an enhancement of this current by one to three orders of magnitude. The model predictions are compared with observations made during the Pioneer 10 and 11 flybys, and satisfactory agreement is obtained.

Dessler, A. J.; Hill, T. W.

1979-01-01

374

Optimizing the mix of strategies for control of vehicular emissions  

SciTech Connect

A number of strategies for the control of vehicular emissions are being considered by the Philippine government to address Metropolitan Manila`s air quality problem. An analytical tool is needed for optimizing criteria pollutant reductions given the budgetary constraints. The simplest approach is to take costs and pollutant removals to be linear with each strategy`s scale of activity, and this is readily solved as a linear programming problem. Another approach is to use a dynamic system of weights which shift with progressive improvements in pollutant emissions. The two approaches yield somewhat different results, suggesting the sensitivity of the solution to the assumed weights. The study also illustrates the importance of a sound methodology for evaluating priorities given to different air quality goals. One such methodology may involve a polling of expert panels and the public to gain insight into the relative importance given to competing emissions reduction goals. An informal polling of resource agency staff was conducted and discussed in this paper. The authors take the position that proper planning involves tracing intermediate steps to the final outcome and not just focusing on the latter. 17 refs., 1 fig., 8 tabs.

Lejano, R.P. [Montgomery Watson, Pasadena, CA (United States)] [Montgomery Watson, Pasadena, CA (United States); Ayala, P.M. [California Air Resources Board, El Monte, CA (United States)] [California Air Resources Board, El Monte, CA (United States); Gonzales, E.A. [Environmental Management Bureau, Quezon City (Philippines)] [Environmental Management Bureau, Quezon City (Philippines)

1997-01-01

375

CONTROL OF TRACE METAL EMISSIONS DURING COAL COMBUSTION  

SciTech Connect

Emissions of toxic trace metals in the form of metal fumes or submicron particulates from a coal-fired combustion source have received greater environmental and regulatory concern over the past years. Current practice of controlling these emissions is to collect them at the cold-end of the process by air-pollution control devices (APCDs) such as electrostatic precipitators and baghouses. However, trace metal fumes may not always be effectively collected by these devices because the formed fumes are extremely small. The proposed research is to explore the opportunities for improved control of toxic trace metal emissions, alternatively, at the hot-end of the coal combustion process, i.e., in the combustion chamber. The technology proposed is to prevent the metal fumes from forming during the process, which would effectively eliminate the metal emission problems. Specifically, the technology is to employ suitable sorbents to (1) reduce the amount of metal volatilization during combustion and (2) capture volatilized metal vapors. The objectives of the project are to demonstrate the technology and to characterize the metal capture process during coal combustion in a fluidized bed combustor. This final technical report details the work performed, the conclusions obtained, and the accomplishments achieved over the project performance period from July 1, 1994 through December 31, 1997. Specifically, this report consists of the following five chapters: Chapter 1. Executive Summary; Chapter 2. Metal Capture by Various Sorbents; Chapter 3. Simultaneous Metal and Sulfur Capture; Chapter 4. Sorption and Desorption of Mercury on Sorbents; and Chapter 5. Project Conclusions. In summary, the metals involved in the project were arsenic, cadmium, chromium, lead, mercury and selenium and the sorbents tested included bauxite, zeolite and calcined limestone. The three sorbents have been found to have various degree of metal capture capability on arsenic, cadmium, chromium and lead. Among them, calcined limestone is capable of simultaneouely capturing metals and sulfur. Mercury and selenium, however, can not be effectively retained by these sorbents under the combustion conditions. Mercury adsorption by sorbents at low temperatures was also investigated and the developed mass transfer model for mercury absorption appears to describe reasonably well the experimental results. Overall, the project has generated 18 presentations and/or publications in professional conferences and journals.

THOMAS C. HO

1998-02-18

376

Control of acid mist emissions from FGD systems  

SciTech Connect

Improved control of acid mist emissions can be achieved by replacing or augmenting the conventional mist eliminators with a wet electrostatic precipitator (WESP). This paper describes a two-phased study performed to determine the degree of control that can be achieved with this approach. Phase I was a study of the electrical operation of a lab-scale WESP collecting an acid mist from a coal combustion pilot plant equipped with a spray chamber. The results of this study were used to develop and validate a computer model of the WESP. In Phase II, measurements were made at two utility scrubber installations to determine the loadings of acid mist, fly ash, and scrubber carryover. These measurements were used as input to the model to project the performance of a retrofitted WESP.

Dahlin, R S [Southern Research Inst., Birmingham, AL (United States)] [Southern Research Inst., Birmingham, AL (United States); Brown, T D [USDOE Pittsburgh Energy Technology Center, PA (United States)] [USDOE Pittsburgh Energy Technology Center, PA (United States)

1991-01-01

377

Environmental factors controlling methane emissions for peatlands in Northern Minnesota  

SciTech Connect

Controls on methane emission from peatlands in northern Minnesota were investigated by correlation to environmental variables and by field manipulations. From September 1988 through September 1990, methane flux measurements were made at weekly to monthly intervals at six sites in the Marcell Experimental Forest, northern Minnesota (two open bog sites, two forested bog sites, a poor fen, and a fen lagg). Flux was related to water table position and peat temperature with simple correlations at individual sites and multiple regression on all sites together. The effect of water table was also investigated experimentally in {open_quotes}bog corrals{close_quotes} (open-ended metal enclosures set in the peat) in which water table was artificially raised to the surface in the driest peatland. Temperature largely controlled variation in flux within individual ecosystems at Marcell, but hydrology distinguished between-site variation. Water table position, peat temperature, and degree of peat humification explained 91% of the variance in log CH{sub 4} flux, predicted annual methane emission from individual wetlands successfully, and predicted the change in flux due to the water table manipulation. Raising the water table in the bog corrals by an average of 6 cm in autumn 1989 and 10 cm in summer 1990 increased emission by 2.5x and 2.2x, respectively. Just as expanding the scale of investigation from a single habitat in a wetland to several wetlands necessitates incorporation of additional variables to explain flux (water table, peat characteristics), modeling flux from several wetland regions, if possible, will require the addition of climate parameters. 30 refs., 8 figs., 21 tabs.

Dise, N.B.; Gorham, E. [Univ. of Minnesota, Minneapolis, MN (United States); Verry, E.S. [Forest Service, Grand Rapids, MN (United States)

1993-06-20

378

Automated Boiler Combustion Controls for Emission Reduction and Efficiency Improvement  

SciTech Connect

In the late 1980s, then President Bush visited Krakow, Poland. The terrible air quality theremotivated him to initiate a USAID-funded program, managed by DOE, entitled ?Krakow Clean Fossil Fuels and Energy Efficiency Program.? The primary objective of this program was to encourage the formation of commercial ventures between U.S. and Polish firms to provide equipment and/or services to reduce pollution from low-emission sources in Krakow, Poland. This program led to the award of a number of cooperative agreements, including one to Control Techtronics International. The technical objective of CTI?s cooperative agreement is to apply combustion controls to existing boiler plants in Krakow and transfer knowledge and technology through a joint U.S. and Polish commercial venture. CTI installed automatic combustion controls on five coal boilers for the district heating system in Krakow. Three of these were for domestic hot-water boilers, and two were for steam for industrial boilers. The following results have occurred due to the addition of CTI?s combustion controls on these five existing boilers: ! 25% energy savings ! 85% reduction in particulate emissions The joint venture company CTI-Polska was then established. Eleven additional technical and costing proposals were initiated to upgrade other coal boilers in Krakow. To date, no co-financing has been made available on the Polish side. CTI-Polska continues in operation, serving customers in Russia and Ukraine. Should the market in Poland materialize, the joint venture company is established there to provide equipment and service.

None

1998-12-02

379

Portable air pollution control equipment for the control of toxic particulate emissions  

SciTech Connect

Chromium VI (Cr VI) has been identified by the environmental regulatory agencies as a potent carcinogen among eleven heavy metals. A threshold level of 0.0001 lb/year for Cr VI emissions has been established by the California Air Resources Board for reporting under Assembly Bill 2588. A need for an innovative control technology to reduce fugitive emissions of Cr VI was identified during the Air Toxic Emissions Reduction Program at Northrop Grumman Military Aircraft Systems Division (NGMASD). NGMASD operates an aircraft assembly facility in El Segundo, CA. Nearly all of the aircraft components are coated with a protective coating (primer) prior to assembly. The primer has Cr VI as a component for its excellent corrosion resistance property. The complex assembly process requires fasteners which also need primer coating. Therefore, NGMASD utilizes High Volume Low Pressure (HVLP) guns for the touch-up spray coating operations. During the touch-up spray coating operations, Cr VI particles are atomized and transferred to the aircraft surface. The South Coast Air Quality Management District (SCAQMD) has determined that the HVLP gun transfers 65% of the paint particles onto the substrate and the remaining 35% are emitted as an overspray if air pollution controls are not applied. NGMASD has developed the Portable Air Pollution Control Equipment (PAPCE) to capture and control the overspray in order to reduce fugitive Cr VI emissions from the touch-up spray coating operations. A source test was performed per SCAQMD guidelines and the final report has been approved by the SCAQMD.

Chaurushia, A.; Odabashian, S.; Busch, E. [Northrop Grumman Corp., El Segundo, CA (United States). Military Aircraft Systems Div.

1997-12-31

380

Nonlinear theory of a two-photon correlated-spontaneous-emission laser: A coherently pumped two-level--two-photon laser  

SciTech Connect

We develop a nonlinear theory of a two-photon correlated-spontaneous-emission laser (CEL) by using an effective interaction Hamiltonian for a two-level system coupled by a two-photon transition. Assuming that the active atoms are prepared initially in a coherent superposition of two atomic levels involved in the two-photon transition, we derive a master equation for the field-density operator by using our quantum theory for coherently pumped lasers. The steady-state properties of the two-photon CEL are studied by converting the field master equation into a Fokker-Planck equation for the antinormal-ordering Q representation of the field-density operator. Because of the injected atomic coherence, the drift and diffusion coefficients become phase sensitive. This leads to laser phase locking and an extra two-photon CEL gain. The laser field can build up from a vacuum in the no-population-inversion region, in contrast to an ordinary two-photon laser for which triggering is needed. We find an approximate steady-state solution of the Q representation for the laser field, which consists of two identical peaks of elliptical type. We calculate the phase variance and, for any given mean photon number, obtain the minimum variance in the phase quadrature as a function of the initial atomic variables. Squeezing of the quantum noise in the phase quadrature is found and it exhibits the following features: (1) it is possible only when the laser intensity is smaller than a certain value; (2) it becomes most significant for small mean photon number, which is achievable in the no-population-inversion region; and (3) a maximum of 50% squeezing can be asymptotically approached in the small laser intensity limit.

Lu, N.; Zhao, F.; Bergou, J.

1989-05-15

381

Light-Duty Vehicle Exhaust Emission Control Cost Estimates Using a Part-Pricing Approach  

Microsoft Academic Search

The substantial reductions in motor vehicle emissions that have occurred since the late 1960s have been accompanied by continuous increases in vehicle emission control costs, and cost increases or decreases due to changes in vehicle performance such as driveability, power, fuel economy, and vehicle maintenance. In this paper, a systematic approach has been developed to estimate emission control costs for

Quanlu Wang; Catherine Kling; Daniel Sperling

1993-01-01

382

Nitrogen Isotopic Composition of Coal-Fired Power Plant NOx: Influence of Emission Controls and Implications for Global Emission  

E-print Network

Nitrogen Isotopic Composition of Coal-Fired Power Plant NOx: Influence of Emission Controls from coal-fired power plants in the U.S. at typical operating conditions with and without the presence this, a novel method for collection and isotopic analysis of coal-fired stack NOx emission samples

Elliott, Emily M.

383

Particulate-phase and gaseous elemental mercury emissions during biomass combustion: controlling factors and correlation with particulate matter emissions.  

PubMed

Mercury emissions from wildfires are significant natural sources of atmospheric mercury, but little is known about what controls speciation of emissions important to mercury deposition processes. The goal of this study was to quantify gaseous elemental mercury (GEM) and particulate-phase mercury (PHg) emissions from biomass combustion to identify key factors controlling the speciation. Emissions were characterized in an exhaust stack 17 m above fires using a gaseous mercury analyzer and quartz-fiber filters. Fuels included fresh and air-dried leaves, needles, and branches with different fuel moistures (9-95% of dry weight) and combustion properties (e.g., from < 10 to 90% of fire durations characterized by flaming phases). Fuel moisture was the overall driving factor defining emissions, with GEM being the dominant fraction (> or = 95%) in low moisture fuels and substantial PHg contributions--up to 50% of total mercury emissions--in fresh fuels. High PHg emissions were observed during smoldering combustion whereas flaming-dominated fires showed insignificant PHg emissions. PHg mass emissions were correlated with particulate matter (PM; r2 = 0.67), organic carbon (OC; r2 = 0.63) and sulfur (S; r2 = 0.46) mass emissions, but not with elemental carbon (EC) nor with the total mercury emissions. These data suggest that the formation of PHg involves similar processes as the formation of particulate OC, for example condensation of volatile species onto preexisting smoke particles during cooling and dilution. Based on the observed relationship between PM and OC mass concentrations and published emission inventories, we estimate global PHg emissions by wildfires of 4-5 Mg yr(-1). PMID:18323093

Obrist, Daniel; Moosmüller, Hans; Schürmann, Roger; Chen, L W Antony; Kreidenweis, Sonia M

2008-02-01

384

CONTROL OF INDUSTRIAL VOC (VOLATILE ORGANIC COMPOUND) EMISSIONS BY CATALYTIC INCINERATION. VOLUME 9. QUALITY ASSURANCE  

EPA Science Inventory

Radian Corporation, under contract to the U.S. Environmental Protection Agency, performed site selection, test plan development, and performance tests of catalytic incinerators used for volatile organic compound (VOC) emissions control at industrial sites. VOC emissions are of co...

385

SURVEY OF EMISSIONS CONTROL AND COMBUSTION EQUIPMENT DATA IN INDUSTRIAL PROCESS HEATING  

EPA Science Inventory

The report discusses the interaction between present and potential energy conservation measures and emission programs in various industries. Where energy conservation goals conflicted with emission control goals, the problems were assessed. Based on these assessments, research an...

386

Controlling air emissions from petrochemical wastewater treatment facilities  

SciTech Connect

A typical wastewater treatment facility contains a number of unit operations in series or parallel usually culminating in a biological treatment system. These would include sewers, flues, grit chambers, sumps, equalization basins, pH adjustment stations, nutrient addition stations, clarifiers, oxidation basins, open or closed top storage tanks, drum or container storage facilities, waste transfer lines, ditches, pipes or trucks, landfills, land treatment sites and biological treatment systems, and the associated equipment. Each of these unit operations is designed either to store or partly purify the waste stream. During storage or purification, chemicals can be removed from the wastewater through physical separation processes to the air, an organic layer, or settling solids or by chemical transformation reactions. These processes include volatilization, extraction, sorption, or sedimentation and physiochemical and biochemical kinetic reactions. This paper summarizes the issues that need to be considered in developing an emission control strategy directed at air emissions resulting from the discharge of organic compounds from a process unit to a wastewater treatment facility, and discusses the application of this methodology to several specific applications.

Berglund, R.L. (Union Carbide Corp., South Charleston, WV (USA))

1988-01-01

387

Spontaneous emission in dielectric nanoparticles  

Microsoft Academic Search

An analytical expression is obtained for the radiative-decay rate of an excited optical center in an ellipsoidal dielectric\\u000a nanoparticle (with sizes much less than the wavelength) surrounded by a dielectric medium. It is found that the ratio of the\\u000a decay rate A\\u000a nano of an excited optical center in the nanoparticle to the decay rate A\\u000a bulk of an excited

K. K. Pukhov; T. T. Basiev; Yu. V. Orlovskii

2008-01-01

388

Quality control of positron emission tomography radiopharmaceuticals: An institutional experience  

PubMed Central

Purpose of the Study: To study quality control parameters of routinely prepared positron emission tomography (PET) radiopharmaceuticals. Materials and Methods: Three PET radiopharmaceuticals fluorine-18 fluorodeoxyglucose (F-18 FDG), N-13 ammonia (N-13 NH3), and Ga-68 DOTATATE (n = 25 each), prepared by standardized protocols were used. The radionuclide purity, radiochemical purity, residual solvents, pH, endotoxins, and sterility of these radiopharmaceuticals were determined. Results: The physical half-life of radionuclide in radiopharmaceuticals, determined by both graphical and formula method, demonstrated purity of radionuclides used. pH of all PET radiopharmaceuticals used was in the range of 5-6.5. No microbial growth was observed in radiopharmaceutical preparations. The residual solvents, chemical impurity, and pyrogens were within the permissible limits. Conclusions: All three PET radiopharmaceuticals were safe for intravenous administration. PMID:24379528

Shukla, Jaya; Vatsa, Rakhee; Garg, Nitasha; Bhusari, Priya; Watts, Ankit; Mittal, Bhagwant R

2013-01-01

389

Controlling satellite communication system unwanted emissions in congested RF spectrum  

NASA Astrophysics Data System (ADS)

The International Telecommunication Union (ITU), a United Nations (UN) agency, is the agency that, under an international treaty, sets radio spectrum usage regulations among member nations. Within the United States of America (USA), the organization that sets regulations, coordinates an application for use, and provides authorization for federal government/agency use of the radio frequency (RF) spectrum is the National Telecommunications and Information Administration (NTIA). In this regard, the NTIA defines which RF spectrum is available for federal government use in the USA, and how it is to be used. The NTIA is a component of the United States (U.S.) Department of Commerce of the federal government. The significance of ITU regulations is that ITU approval is required for U.S. federal government/agency permission to use the RF spectrum outside of U.S. boundaries. All member nations have signed a treaty to do so. U.S. federal regulations for federal use of the RF spectrum are found in the Manual of Regulations and Procedures for Federal Radio Frequency Management, and extracts of the manual are found in what is known as the Table of Frequency Allocations. Nonfederal government and private sector use of the RF spectrum within the U.S. is regulated by the Federal Communications Commission (FCC). There is a need to control "unwanted emissions" (defined to include out-of-band emissions, which are those immediately adjacent to the necessary and allocated bandwidth, plus spurious emissions) to preclude interference to all other authorized users. This paper discusses the causes, effects, and mitigation of unwanted RF emissions to systems in adjacent spectra. Digital modulations are widely used in today's satellite communications. Commercial communications sector standards are covered for the most part worldwide by Digital Video Broadcast - Satellite (DVB-S) and digital satellite news gathering (DSNG) evolutions and the second generation of DVB-S (DVB-S2) standard, developed by the European Telecommunications Standards Institute (ETSI). In the USA, the Advanced Television Systems Committee (ATSC) has adopted Europe's DVB-S and DVB-S2 standards for satellite digital transmission. With today's digital modulations, RF spectral side lobes can extend out many times the modulating frequency on either side of the carrier at excessive power levels unless filtered. Higher-order digital modulations include quadrature phase shift keying (QPSK), 8 PSK (8-ary phase shift keying), 16 APSK (also called 12-4 APSK (amplitude phase shift keying)), and 16 QAM (quadrature amplitude modulation); they are key for higher spectrum efficiency to enable higher data rate transmissions in limited available bandwidths. Nonlinear high-power amplifiers (HPAs) can regenerate frequency spectral side lobes on input-filtered digital modulations. The paper discusses technologies and techniques for controlling these spectral side lobes, such as the use of square root raised cosine (SRRC) filtering before or during the modulation process, HPA output power back-off (OPBO), and RF filters after the HPA. Spectral mask specifications are a common method of the NTIA and ITU to define spectral occupancy power limits. They are intended to reduce interference among RF spectrum users by limiting excessive radiation at frequencies beyond the regulatory allocated bandwidth.The focus here is on the communication systems of U.S. government satellites used for space research, space operations, Earth exploration satellite services (EESS), meteorological satellite services (METSATS), and other government services. The 8025 to 8400 megahertz (MHz) X band can be used to illustrate the "unwanted emissions" issue. 8025 to 8400 MHz abuts the 8400 to 8450 MHz band allocated by the NTIA and ITU to space research for space-to-Earth transmissions such as receiving very weak Deep Space Network signals. The views and ideas expressed in this paper are those of the authors and do not necessarily reflect those of The Aerospace Corporation or The National Oceanic and Atmosphe

Olsen, Donald; Heymann, Roger

2007-09-01

390

A bi-hemispheric neuronal network model of the cerebellum with spontaneous climbing fiber firing produces asymmetrical motor learning during robot control  

PubMed Central

To acquire and maintain precise movement controls over a lifespan, changes in the physical and physiological characteristics of muscles must be compensated for adaptively. The cerebellum plays a crucial role in such adaptation. Changes in muscle characteristics are not always symmetrical. For example, it is unlikely that muscles that bend and straighten a joint will change to the same degree. Thus, different (i.e., asymmetrical) adaptation is required for bending and straightening motions. To date, little is known about the role of the cerebellum in asymmetrical adaptation. Here, we investigate the cerebellar mechanisms required for asymmetrical adaptation using a bi-hemispheric cerebellar neuronal network model (biCNN). The bi-hemispheric structure is inspired by the observation that lesioning one hemisphere reduces motor performance asymmetrically. The biCNN model was constructed to run in real-time and used to control an unstable two-wheeled balancing robot. The load of the robot and its environment were modified to create asymmetrical perturbations. Plasticity at parallel fiber-Purkinje cell synapses in the biCNN model was driven by error signal in the climbing fiber (cf) input. This cf input was configured to increase and decrease its firing rate from its spontaneous firing rate (approximately 1 Hz) with sensory errors in the preferred and non-preferred direction of each hemisphere, as demonstrated in the monkey cerebellum. Our results showed that asymmetrical conditions were successfully handled by the biCNN model, in contrast to a single hemisphere model or a classical non-adaptive proportional and derivative controller. Further, the spontaneous activity of the cf, while relatively small, was critical for balancing the contribution of each cerebellar hemisphere to the overall motor command sent to the robot. Eliminating the spontaneous activity compromised the asymmetrical learning capabilities of the biCNN model. Thus, we conclude that a bi-hemispheric structure and adequate spontaneous activity of cf inputs are critical for cerebellar asymmetrical motor learning.

Pinzon-Morales, Ruben-Dario; Hirata, Yutaka

2014-01-01

391

Spontaneous emission of a two-level static atom coupling with the electromagnetic vacuum fluctuations outside a high-dimensional Einstein Gauss-Bonnet black hole  

E-print Network

In present paper, by using the generalized DDC formalism, we investigate the spontaneous excitation of an static atom interacting with electromagnetic vacuum fluctuations outside a EGB black hole in $d$-dimensions. We find that spontaneous excitation does not occur in Boulware vacuum. The Gauss-Bonnet term has no effect on the stability of the atom. Finally, we discuss the contribution of the coupling constant and dimensional factor to the results in three different kinds of spacetime.

Ming Zhang; Zhan-Ying Yang; Rui-Hong Yue

2014-06-19

392

The next decade and emission controls for electric utilities  

SciTech Connect

The historical efforts to achieve attainment with the ozone and particulate related standards span over 25 years and involve billions of dollars with only minimal success related to ozone and unknown success related to certain fine particulates. The 1990 Clean Air Act Amendments mandated significant new efforts, including Title IV - Acid Rain, to achieve reductions in ozone and fine particulate precursors and attainment with the standards. Initial reduction efforts have only recently been implemented and yet another hot summer continues to portray our futile efforts to gain much ground towards attainment with existing and revised or new standards. In order to review the issues more fully and to investigate the issue of regional transport. EPA has given the states a reprieve on ozone attainment plans until mid-1997 and set up the Clean Air Act Advisory Committee (CAAAC) structure to review implementation issues with new or revised standards. The states and other stockholders are involved in these EPA processes through the Ozone Transport Assessment Group (OTAG) and the CAAAC along with numerous working groups to get new answers arid help towards innovative solutions. A major target in these efforts is emissions from fossil-fuel fired utility boilers. The OTAG process has developed regional control strategy targets for utility NO{sub x} sources at three levels. These levels include consideration of costs, timing and availability of controls, and the anticipated reductions in NO{sub x}. The CAAAC is also considering regional controls and the associated implementation issues for both ozone and fine particulates. EPA is also considering a Clean Air Power Initiative (CAPI) to wrap all the utility control issues in a single consensus package. The next 10 years will be a crucial time for electric utilities in juggling environmental and competitive issues.

Herrin, W.D. [Southern Company Services, Birmingham, AL (United States)

1997-12-31

393

Randomized controlled trial of probiotics for the prevention of spontaneous preterm delivery associated with intrauterine infection: study protocol  

Microsoft Academic Search

BACKGROUND: Spontaneous preterm deliveries that occur before the 34th week of gestation, and particularly before the 32nd week of gestation, have been strongly associated to intrauterine infection, ascending from vagina, and represent the largest portion of neonatal deaths and neurological problems. Bacterial vaginosis, characterized by a diminished or absent flora of lactobacilli and increased colonization of several anaerobic or facultative

Leticia Krauss-Silva; Maria Elizabeth L Moreira; Mariane B Alves; Maria R Rezende; Alcione Braga; Karla G Camacho; Maria Rosa R Batista; Clarisse Savastano; Antonio Almada-Horta; Fernando Guerra

2010-01-01

394

Dopamine and Cognitive Control: The Influence of Spontaneous Eyeblink Rate and Dopamine Gene Polymorphisms on Perseveration and Distractibility  

Microsoft Academic Search

One fundamental problem of intelligent organisms pursuing goal-directed behavior is how to dynamically regulate the balance between maintenance and flexibility. The authors show that central dopaminergic activity, as indicated by spontaneous eyeblink rate and dopamine gene polymorphisms, plays an important role in the modulation of this balance. Seventy-two young adults were examined. Participants with high blink rates showed increased cognitive

Gesine Dreisbach; Johannes Müller; Thomas Goschke; Alexander Strobel; Katja Schulze; Klaus-Peter Lesch; Burkhard Brocke

2005-01-01

395

Optical sensors for process control and emissions monitoring in industry  

SciTech Connect

Sandia National Laboratories has a number of ongoing projects developing optical sensors for industrial environments. Laser-based sensors can be attractive for relatively harsh environments where extractive sampling is difficult, inaccurate, or impractical. Tools developed primarily for laboratory research can often be adapted for the real world and applied to problems far from their original uses. Spectroscopic techniques, appropriately selected, have the potential to impact the bottom line of a number of industries and industrial processes. In this paper the authors discuss three such applications: a laser-based instrument for process control in steelmaking, a laser-induced breakdown method for hazardous metal detection in process streams, and a laser-based imaging sensor for evaluating surface cleanliness. Each has the potential to provide critical, process-related information in a real-time, continuous manner. These sensor techniques encompass process control applications and emissions monitoring for pollution prevention. They also span the range from a field-tested pre-commercial prototype to laboratory instrumentation. Finally, these sensors employ a wide range of sophistication in both the laser source and associated analytical spectroscopy. In the ultimate applications, however, many attributes of the sensors are in common, such as the need for robust operation and hardening for harsh industrial environments.

S. W. Alendorf; D. K. Ottensen; D. W. Hahn; T. J. Kulp; U. B. Goers

1999-01-01

396

Humidity control of particle emissions in aeolian systems  

NASA Astrophysics Data System (ADS)

Humidity is an important control of the wind speed required to entrain particles into an air flow and is well known to vary on a global scale, as do dust emissions. This paper reports on wind tunnel experiments which quantify this control through placing a polymer capacitance sensor immediately at the bed surface. The sensor measured changes in the humidity (RH) of the pore air in real time. RH was varied between 15% and 80% and the critical wind speed determined for the release of particles to the air stream. The results strongly support earlier suggestions that fine particles are most affected in relatively dry atmospheres, particularly those which are tightly packed. An analytical model is proposed to describe this relationship which depends on determination of the matric potential from the Kelvin equation. The total contact area between particle asperities adjoined by pendular rings is represented as a power function of the number of layers of adsorbed water. The value of the exponent appears to be governed by the surface roughness of the particles and their packing arrangement. Parallel developments in colloid interface science and atomic force microscopy, relevant to industrial and pharmaceutical applications, support these conclusions in principle and will likely have an important bearing on future progress in parameterization of the proposed model.

McKenna Neuman, Cheryl; Sanderson, Steven

2008-06-01

397

Investigation of the Effects of Biodiesel-based Na on Emissions Control Components  

Microsoft Academic Search

A single-cylinder diesel engine was used to investigate the impact of biodiesel-based Na on emissions control components using specially blended 20% biodiesel fuel (B20). The emissions control components investigated were a diesel oxidation catalyst (DOC), a Cu-zeolite-based NHâ-SCR (selective catalytic reduction) catalyst, and a diesel particulate filter (DPF). Both light-duty vehicle, DOC-SCR-DPF, and heavy-duty vehicle, DOC-DPF-SCR, emissions control configurations were

D. William Brookshear; Ke Nguyen; Todd J Toops; Bruce G Bunting; Janet E Howe

2012-01-01

398

Three-Dimensional Composite Nanostructures for Lean NOx Emission Control  

SciTech Connect

This final report to the Department of Energy (DOE) and National Energy Technology Laboratory (NETL) for DE-EE0000210 covers the period from October 1, 2009 to July 31, 2013. Under this project, DOE awarded UConn about $1,248,242 to conduct the research and development on a new class of 3D composite nanostructure based catalysts for lean NOx emission control. Much of the material presented here has already been submitted to DOE/NETL in quarterly technical reports. In this project, through a scalable solution process, we have successfully fabricated a new class of catalytic reactors, i.e., the composite nanostructure array (nano-array) based catalytic converters. These nanocatalysts, distinct from traditional powder washcoat based catalytic converters, directly integrate monolithic substrates together with nanostructures with well-defined size and shape during the scalable hydrothermal process. The new monolithic nanocatalysts are demonstrated to be able to save raw materials including Pt-group metals and support metal oxides by an order of magnitude, while perform well at various oxidation (e.g., CO oxidation and NO oxidation) and reduction reactions (H{sub 2} reduction of NOx) involved in the lean NOx emissions. The size, shape and arrangement of the composite nanostructures within the monolithic substrates are found to be the key in enabling the drastically reduced materials usage while maintaining the good catalytic reactivity in the enabled devices. The further understanding of the reaction kinetics associated with the unique mass transport and surface chemistry behind is needed for further optimizing the design and fabrication of good nanostructure array based catalytic converters. On the other hand, the high temperature stability, hydrothermal aging stability, as well as S-poisoning resistance have been investigated in this project on the nanocatalysts, which revealed promising results toward good chemical and mechanical robustness, as well as S-poisoning resistance. Further investigation is needed for unraveling the understanding, design and selection principles of this new class of nanostructure based monolithic catalysts.

Gao, Pu-Xian

2013-07-31

399

Theoretical Calculation of System Performance of Fiber Optic Network with Chromatic Dispersion, Polarization Mode Dispersion, Polarization Dependent Loss, and Amplifier Spontaneous Emission Noise  

NASA Astrophysics Data System (ADS)

This thesis includes a theoretical study of the performance of an optical network system with linear impairments: chromatic dispersion (CD), polarization mode dispersion (PMD), polarization dependent loss (PDL), and amplified spontaneous emission (ASE) noise. Both the a-factor and bit error rate (BER) were used as performance parameters in this study. First, an analytical optical eye diagram evaluation for a system of highly mode coupled PMD/PDL fiber and lumped sections (up to fifteen sections) have been presented in this study. Based on this evaluation we found that with PDL considered as well as PMD, the a-factor of the output becomes higher than that of a Maxwellian fiber having the same total root mean-squared PMD and PDL values, when the mean-square PDL element of the lumped sections makes up the major portion of the total mean-square of the whole system. Whereas without considering PDL, the a-factor becomes higher as the mean-square PMD element of the Maxwellian fiber takes the major portion of the total mean-square PMD element of the whole system. Also the worst case for the a-factor occurred when the lumped sections were in the middle between two equivalent Maxwellian fibers, rether than if the lumped sections were followed by Maxwellian fiber or the Maxwellian fiber is followed by the lumped sections. We also note that two equivalent Maxwellian fibers connected in series will not give the same a-factor as a Maxwellian fiber equivalent calculated by concatenation rules unless they have the same values of PMD, PDL, and polarization direction correlation elements. Second, considering ASE-noise besides CD, PMD, and PDL, improved values of bit error rate (BER) were gotten using the moment generation function for the optical system in cases of ON-OFF modulation format and DPSK modulation format. We found that, even when considering the noise only without the signal, the probability density function of the output current was dependent on the output state of polarization.

Abuzariba, Suad Mohamed

400

Fine particle (2.5 microns) emissions: regulations, measurement, and control  

SciTech Connect

Contents: Introduction; Health effects; Air monitoring; Emission control methods - fabric filter/baghouses, electrostatic precipitators, wet scrubbers; Environmental technology verification and baghouse filtration products; Cost considerations; and Nanoparticulates.

John D. McKenna; James H. Turner; James P. McKenna, Jr.

2008-09-15

401

Control of air pollution from aviation: the emission standard setting process  

Microsoft Academic Search

Air pollutant emissions from aviation sources are a small but increasing part of all emissions on a national scale. The United States Environmental Protection Agency first issued emission standards for aircraft engines in 1973 and has repeatedly changed the control regulations since that time. Critics claim the standards are too stringent and do not solve any real air pollution problems.

Naugle

1981-01-01

402

Environmental and developmental controls over the seasonal pattern of isoprene emission from aspen leaves  

Microsoft Academic Search

Isoprene emission from plants represents one of the principal biospheric controls over the oxidative capacity of the continental troposphere. In the study reported here, the seasonal pattern of isoprene emission, and its underlying determinants, were studied for aspen trees growing in the Rocky Mountains of Colorado. The springtime onset of isoprene emission was delayed for up to 4 weeks following

R. K. Monson; P. C. Harley; M. E. Litvak; M. Wildermuth; A. B. Guenther; P. R. Zimmerman; R. Fall

1994-01-01

403

COST EFFECTIVE VOC EMISSION CONTROL STARTEGIES FOR MILITARY, AEROSPACE,AND INDUSTRIAL PAINT SPRAY BOOTH OPERATIONS: COMBINING IMPROVED VENTILATION SYSTEMS WITH INNOVATIVE, LOW COST EMISSION CONTROL TECHNOLOGIES  

EPA Science Inventory

The paper describes a full-scale demonstration program in which several paint booths were modified for recirculation ventilation; the booth exhaust streams are vented to an innovative volatile organic compound (VOC) emission control system having extremely low operating costs. ...

404

Estimation of automobile emissions and control strategies in India.  

PubMed

Rapid, but unplanned urban development and the consequent urban sprawl coupled with economic growth have aggravated auto dependency in India over the last two decades. This has resulted in congestion and pollution in cities. The central and state governments have taken many ameliorative measures to reduce vehicular emissions. However, evolution of scientific methods for emission inventory is crucial. Therefore, an attempt has been made to estimate the emissions (running and start) from on-road vehicles in Chennai using IVE model in this paper. GPS was used to collect driving patterns. The estimated emissions from motor vehicles in Chennai in 2005 were 431, 119, 46, 7, 4575, 29, and 0.41 tons/days respectively for CO, VOC, NO(x), PM, CO(2,) CH(4) and N(2)O. It is observed from the results that air quality in Chennai has degraded. The estimation revealed that two and three-wheelers emitted about 64% of the total CO emissions and heavy-duty vehicles accounted for more than 60% and 36% of the NO(x) and PM emissions respectively. About 19% of total emissions were that of start emissions. It is also estimated that on-road transport contributes about 6637 tons/day CO(2) equivalent in Chennai. This paper has further examined various mitigation options to reduce vehicular emissions. The study has concluded that advanced vehicular technology and augmentation of public transit would have significant impact on reducing vehicular emissions. PMID:20149922

Nesamani, K S

2010-03-15

405

Energy, Carbon-emission and Financial Savings from Thermostat Control  

SciTech Connect

Among the easiest approaches to energy, and cost, savings for most people is the adjustment of thermostats to save energy. Here we estimate savings of energy, carbon, and money in the United States of America (USA) that would result from adjusting thermostats in residential and commercial buildings by about half a degree Celsius downward during the heating season and upward during the cooling season. To obtain as small a unit as possible, and therefore the least likely to be noticeable by most people, we selected an adjustment of one degree Fahrenheit (0.56 degree Celsius) which is the gradation used almost exclusively on thermostats in the USA and is the smallest unit of temperature that has been used historically. Heating and/or cooling of interior building space for personal comfort is sometimes referred to as space conditioning, a term we will use for convenience throughout this work without consideration of humidity. Thermostat adjustment, as we use the term here, applies to thermostats that control the indoor temperature, and not to other thermostats such as those on water heaters. We track emissions of carbon only, rather than of carbon dioxide, because carbon atoms change atomic partners as they move through the carbon cycle, from atmosphere to biosphere or ocean and, on longer time scales, through the rock cycle. To convert a mass of carbon to an equivalent mass of carbon dioxide (thereby including the mass of the 2 oxygen atoms in each molecule) simply multiply by 3.67.

Blasing, T J [ORNL; Schroeder, Dana [University of Georgia, Athens, GA

2013-08-01

406

Emission Controls Using Different Temperatures of Combustion Air  

PubMed Central

The effort of many manufacturers of heat sources is to achieve the maximum efficiency of energy transformation chemically bound in the fuel to heat. Therefore, it is necessary to streamline the combustion process and minimize the formation of emission during combustion. The paper presents an analysis of the combustion air temperature to the heat performance and emission parameters of burning biomass. In the second part of the paper the impact of different dendromass on formation of emissions in small heat source is evaluated. The measured results show that the regulation of the temperature of the combustion air has an effect on concentration of emissions from the combustion of biomass. PMID:24971376

Holubcik, Michal; Papucik, Stefan

2014-01-01

407

Emission controls using different temperatures of combustion air.  

PubMed

The effort of many manufacturers of heat sources is to achieve the maximum efficiency of energy transformation chemically bound in the fuel to heat. Therefore, it is necessary to streamline the combustion process and minimize the formation of emission during combustion. The paper presents an analysis of the combustion air temperature to the heat performance and emission parameters of burning biomass. In the second part of the paper the impact of different dendromass on formation of emissions in small heat source is evaluated. The measured results show that the regulation of the temperature of the combustion air has an effect on concentration of emissions from the combustion of biomass. PMID:24971376

Nosek, Radovan; Holub?ík, Michal; Papu?ík, Štefan

2014-01-01

408

FUEL FORMULATION EFFECTS ON DIESEL FUEL INJECTION, COMBUSTION, EMISSIONS AND EMISSION CONTROL  

SciTech Connect

This paper describes work under a U.S. DOE sponsored Ultra Clean Fuels project entitled ''Ultra Clean Fuels from Natural Gas,'' Cooperative Agreement No. DE-FC26-01NT41098. In this study we have examined the incremental benefits of moving from low sulfur diesel fuel and ultra low sulfur diesel fuel to an ultra clean fuel, Fischer-Tropsch diesel fuel produced from natural gas. Blending with biodiesel, B100, was also considered. The impact of fuel formulation on fuel injection timing, bulk modulus of compressibility, in-cylinder combustion processes, gaseous and particulate emissions, DPF regeneration temperature and urea-SCR NOx control has been examined. The primary test engine is a 5.9L Cummins ISB, which has been instrumented for in-cylinder combustion analysis and in-cylinder visualization with an engine videoscope. A single-cylinder engine has also been used to examine in detail the impacts of fuel formulation on injection timing in a pump-line-nozzle fueling system, to assist in the interpretation of results from the ISB engine.

Boehman, A; Alam, M; Song, J; Acharya, R; Szybist, J; Zello, V; Miller, K

2003-08-24

409

EVALUATION OF NOX EMISSION CONTROL CATALYSTS FOR POWER PLANT SCR INSTALLATIONS  

EPA Science Inventory

The paper gives results of an evaluation of nitrogen oxide (NOx) emission control catalysts commercially developed for power plant selective catalytic reduction (SCR) installations. ith the objective of establishing the performance of SCR catalysts and related technology, control...

410

Synergy between Pollution and Carbon Emissions Control: Comparing China and the U.S.  

E-print Network

We estimate the potential synergy between pollution and climate control in the U.S. and China, summarizing the results as emissions cross-elasticities of control. We set a range of NOx and SO2 targets, and record the ...

Nam, Kyung-Min

411

Control of NOx Emissions from Stationary Combustion Sources  

EPA Science Inventory

In general, NOx control technologies are categorized as being either primary control technologies or secondary control technologies. Primary control technologies reduce the formation of NOx in the primary combustion zone. In contrast, secondary control technologies destroy the NO...

412

Exhaust emission control of S. I. engines by engine modification: the SEEC-T system  

Microsoft Academic Search

The recently developed SEEC-T (Subaru Exhaust Emission Control--Thermal and Thermodynamic Control ) system meets the 1977 emission standards of the United States including California and the 1976 standards of Japan without catalytic converters or thermal reactors and will satisfy the more stringent emission standards expected in the future. The SEEC-T system reduces HC, CO and NO\\/sub x\\/ by the following

T. Fukushima; H. Nakamura; T. Sakai

1977-01-01

413

COMBUSTION CONTROL OF ORGANIC EMISSIONS FROM MUNICIPAL WASTE COMBUSTORS  

EPA Science Inventory

More than two decades ago, researchers identified benzo(a)pyrene and other organic species in the emissions from incineration of solid waste. Chlorinated dibenzo-p-dioxins and-furans (CDD/CDF) were first detected in municipal waste combustor (MWC) emissions in 1977. Since then, C...

414

Study about injury and control of vehicle emission to person  

Microsoft Academic Search

With the development of vehicle industry, the vehicles bring much convenience as well as much pollution to our daily life which took injury and threaten to our health. This paper has elaborated the current domestic and international vehiclemotive emission pollution situation and characteristics. it also analyzed the injury mechanism and consequences of emission gas such as carbon monoxide and nitrogen

Hongyan Lin; Guo Liu

2011-01-01

415

CHARACTERIZATION OF EMISSIONS FROM COMBUSTION SOURCES: CONTROLLED STUDIES  

EPA Science Inventory

The paper summarizes Session I papers (given at the EPA Workshop on Characterization of Contaminant Emissions from Indoor Sources, Chapel Hill, NC, May 1985) that illustrate the progress made to date on characterizing indoor combustion emissions from unvented space heaters, gas a...

416

FIELD TESTING OF EMISSION CONTROLS FOR ASBESTOS MANUFACTURING WASTE PILES  

EPA Science Inventory

Abatement of fugitive emissions from asbestos cement waste disposal activities has been studied. The primary sources of asbestos emissions are, (1) transfer of baghouse fines to the dump, (2) crushing and leveling of waste on the fines, (3) active dump areas, (4) inactive dump ar...

417

Vehicular Diesel control emissions benefit assessment in Mexico City  

NASA Astrophysics Data System (ADS)

Diesel vehicles contribute in an important proportion to the particle and black carbon (BC) ambient concentrations in urban areas. These pollutants can effect the climate and health. The average age of the Diesel fleet in Mexico is 15 year-old. An introduction of new technologies and retrofit systems can reduce emissions from this type of vehicles. A set of policies were selected and applied in order to identify their economic benefits in health. An air quality model was used to obtain ambient concentrations from the emissions and specific methodology for emissions inventory adjustment was developed for this project. Preliminary results show an important benefit due to the improvement of the emissions reduction from the Diesel fleet. PM2.5 differences for reduction scenario case 1 and base case. Output from WRF-chem using 2005 Naional Emissions Inventory Reductions obtained using data from the initial fleet, fleet temporal variation and substitution policies.

Garcia-Reynoso, J.; Jazcilevich, A. D.; Ruiz-Suarez, L.; Cruz-Nuñez, X.; Rojas, A. R.; Tripp, M. R.

2013-12-01

418

Management controls on nitrous oxide emissions from row crop agriculture  

NASA Astrophysics Data System (ADS)

Agriculture is a significant source of the potent greenhouse gas (GHG) nitrous oxide (N2O), accounting for ~70% of total anthropic N2O emissions in the US primarily as a result of N fertilizer application. Emissions of N2O are the largest contributor to the global warming potential of row-crop agriculture. Management, including choice of crop type and rotation strongly impacts N2O emissions, but continuous emissions data from row-crops over multiple rotations are lacking. Empirical quantification of these long-term emissions and the development of crop- and rotation-specific N2O emission factors are vital for improving estimates of agricultural GHG emissions, important for informing management practices to reduce agriculture's GHG footprint, and developing mitigation protocols for environmental markets. Over 20 years we measured soil N2O emissions and calculated crop and management specific emission factors in four continuous rotations of corn (Zea mays) - soybean (Glycine max) - wheat (Triticum aestivum) under conventional tillage (CT), zero tillage (NT), low chemical input (LI), and biologically (Org) based management. Two of these systems (LI and Org) included winter cover crops, red clover (Trifolium pratense) or ray (Secale cereale). While average soil N2O fluxes in all systems where similar (2.9±0.2 to 3.8±0.5 g N2O-N ha-1 d-1), there was a significant interaction of total emissions with crop and phase. Surprisingly, the lowest total emissions from the corn period of the rotation were from CT, and the highest from LI, with 608±4 and 983±8 g N2O-N ha-1 crop year-1, respectively. Total emissions during the wheat period of the rotation showed the opposite trend, with total emissions of 942±7 and 524±38 g N2O-N ha-1 crop year-1, for CT ant LI, respectively. Total emissions from the soybean period of the rotation were highest under NT and lowest under CT management (526±5 and 296±2 g N2O-N ha-1 crop year-1, respectively). Emission efficiency, N2O emitted for grain produced, was lowest in CT and highest in Org for corn (0.10 and 0.22 g N2O-N kg-1 grain, respectively). For wheat the emission efficiencies were similar for CT and Org systems, despite N2O emissions from CT being almost double those from Org, reflecting the low grain yields under biological management. For soybean, the emission factors were consistent with total emissions due to similar soybean yields across practices, and were between 0.13 and 0.20 g N2O-N kg-1 grain, for CT and NT, respectively. Based on long-term measurements we show that management choices a) has a major effect on N2O emissions, even under the same rotation, and b) provide different potential mitigation opportunities.

Gelfand, I.; Shcherbak, I.; Millar, N.; Robertson, G. P.

2011-12-01

419

Engine Tune-up Service. Unit 6: Emission Control Systems. Student Guide. Automotive Mechanics Curriculum.  

ERIC Educational Resources Information Center

This student guide is for Unit 6, Emission Control Systems, in the Engine Tune-Up Service portion of the Automotive Mechanics Curriculum. It deals with inspecting, testing, and servicing an emission control system. A companion review exercise book and posttests are available separately as CE 031 221-222. An introduction tells how this unit fits…

Bacon, E. Miles

420

ASSESSMENT OF ROAD CARPET FOR CONTROL OF FUGITIVE EMISSIONS FROM UNPAVED ROADS  

EPA Science Inventory

The report gives results of an assessment of the use of carpeting to control fugitive emissions from unpaved roads. Historically, emissions from unpaved roads have been controlled by watering, oiling, or chemical soil stabilization. An analysis of the forces which produce emissio...

421

THz emission from coherently controlled photocurrents in GaAs D. Co^tea)  

E-print Network

THz emission from coherently controlled photocurrents in GaAs D. Co^te´a) and J. M. FraserAs at 295 K. For 90 fs, 1550 and 775 nm optical pulses, we obtain phase-controllable near-single cycle 4 THz radiation. Higher frequency THz emission should be achievable with shorter pulses. At a 250 kHz repetition

Van Driel, Henry M.

422

Engine Performance (Section C: Emission Control Systems). Auto Mechanics Curriculum Guide. Module 3. Instructor's Guide.  

ERIC Educational Resources Information Center

This engine performance (emission control systems) module is one of a series of competency-based modules in the Missouri Auto Mechanics Curriculum Guide. Topics of this module's five units are: positive crankcase ventilation (PCV) and evaporative emission control systems; exhaust gas recirculation (EGR); air injection and catalytic converters;…

Rains, Larry

423

ORGANIC EMISSIONS FROM FERROUS METALLURGICAL INDUSTRIES: COMPILATION OF EMISSION FACTORS AND CONTROL TECHNOLOGIES  

EPA Science Inventory

The report gives results of a review and analysis of the information and data available in the public domain on organic emissions from the ferrous metallurgy industry, specifically the iron and steel, iron foundry, and ferroalloy industries. Emission sources and information gaps ...

424

Risk factors and surgical outcomes for spontaneous rupture of BCLC stages A and B hepatocellular carcinoma: A case-control study  

PubMed Central

AIM: To investigate the risk factors and surgical outcomes for spontaneous rupture of Barcelona Clinic Liver Cancer (BCLC) stages A and B hepatocellular carcinoma (HCC). METHODS: From April 2002 to November 2006, 92 consecutive patients with spontaneous rupture of BCLC stage A or B HCC undergoing hepatic resection were included in a case group. A control arm of 184 cases (1:2 ratio) was chosen by matching the age, sex, BCLC stage and time of admission among the 2904 consecutive patients with non-ruptured HCC undergoing hepatic resection. Histological confirmation of HCC was available for all patients and ruptured HCC was confirmed by focal discontinuity of the tumor with surrounding perihepatic hematoma observed intraoperatively. Patients with microvascular thrombus in the hepatic vein branches were excluded from the study. Clinical data and survival time were collected and analysed. RESULTS: Sixteen patients were excluded from the study based on exclusion criteria, of whom 3 were in the case group and 13 in the control group. Compared with the control group, more patients in the case group had underlying diseases of hypertension (10.1% vs 3.5%, P = 0.030) and liver cirrhosis (82.0% vs 57.9%, P < 0.001). Tumors in 67 (75.3%) patients in the case group were located in segments II, III and VI, and the figure in the control group was also 67 (39.7%) (P < 0.001). On multivariate analysis, hypertension (HR = 7.38, 95%CI: 1.91-28.58, P = 0.004), liver cirrhosis (HR = 6.04, 95%CI: 2.83-12.88, P < 0.001) and tumor location in segments II, III and VI (HR = 5.03, 95%CI: 2.70-6.37, P < 0.001) were predictive for spontaneous rupture of HCC. In the case group, the median survival time and median disease-free survival time were 12 mo (range: 1-78 mo) and 4 mo (range: 0-78 mo), respectively. The 1-, 3- and 5-year overall survival rates and disease-free survival rates were 66.3%, 23.4% and 10.1%, and 57.0%, 16.8% and 4.5%, respectively. Only radical resection remained predictive for overall survival (HR = 0.32, 95%CI: 0.08-0.61, P = 0.015) and disease-free survival (HR = 0.12, 95%CI: 0.01-0.73, P = 0.002). CONCLUSION: Tumor location, hypertension and liver cirrhosis are associated with spontaneous rupture of HCC. One-stage hepatectomy should be recommended to patients with BCLC stages A and B disease. PMID:25083085

Li, Jing; Huang, Liang; Liu, Cai-Feng; Cao, Jie; Yan, Jian-Jun; Xu, Feng; Wu, Meng-Chao; Yan, Yi-Qun

2014-01-01

425

Control technology for radioactive emissions to the atmosphere at US Department of Energy facilities  

SciTech Connect

The purpose of this report is to provide information to the US Environmental Protection agency (EPA) on existing technology for the control of radionuclide emissions into the air from US Department of Energy (DOE) facilities, and to provide EPA with information on possible additional control technologies that could be used to further reduce these emissions. Included in this report are generic discussions of emission control technologies for particulates, iodine, rare gases, and tritium. Also included are specific discussions of existing emission control technologies at 25 DOE facilities. Potential additional emission control technologies are discussed for 14 of these facilities. The facilities discussed were selected by EPA on the basis of preliminary radiation pathway analyses. 170 references, 131 figures, 104 tables.

Moore, E.B.

1984-10-01

426

Climatic and Chemical Controls on Methane Emissions from Wetlands  

NASA Technical Reports Server (NTRS)

Natural wetlands are the largest single source of methane to the atmosphere and the only one dominated by climate. Although interannual variations in methane emissions from short-term climate variations are becoming better understood, major uncertainties remain with respect to the sensitivity of wetlands and their CH4 emissions to climate variability, the sensitivity of suppression of wetland methane missions to changes in low-dose sulfate deposition, and the response of wetland dynamics to climate variations. We present results from modeling, field, and remote sensing research that integrate current understanding of the dynamics of wetlands and their methane emissions.

Matthews, Elaine; Gauci, Vincent; Prigent, Catherine; Travis, Larry (Technical Monitor)

2002-01-01

427

Controlling light-emission properties of power scalable fiber lasers  

NASA Astrophysics Data System (ADS)

We present several methods controlling light-emission properties in power-scalable fiber lasers, including modal quality, polarization, spectra, and optical nonlinearities. The thesis contains three major parts. In the first part we present high power fiber lasers and high energy fiber amplifiers based on LMA fibers, which need external mode management techniques to maintain diffraction-limited output quality. The 810W high power CW fiber laser, which produces the highest diffraction-limited fiber laser power in 2004, uses coiling to maintain only one mode propagating in 20 mum-core LMA fibers. Thermal analysis shows pump power is not a limiting factor for further power scaling, and according to numerical modeling results, nonlinear threshold can be increased to >2kW. A 405W single-polarization fiber laser uses coiling method onto PM LMA fibers, in which the polarization is totally controlled by coiling, relying on no free-space polarization components. One fiber Bragg grating (FBG) is used both to stabilize output spectrums and to increase SRS threshold. A monolithic high-energy nanosecond fiber amplifier, based on single-mode excitation tapering, demonstrates 26-28dB gain with diffraction-limited output beam quality. Chirally-Coupled-Core fibers are presented in the second part for effectively single-mode performance, which means only one mode is allowed to propagate even when core sizes are large (V>>2.405). The theoretical concepts and analysis of CCC fibers are given. The experimental measurements of our 35 mum-core CCC fibers show consistency with numerical model. Monolithic operation such as mode-preserving splicing and fiber pigtailing is enabled by using CCC fibers, and the suppression of inter-modal scattering allows better performance than conventional LMA fibers. The third part contains the experimental characterization of SBS suppression. With the additional acoustic layer structure we experimentally measure ˜2.5 times SBS suppression. The method is compatible with other techniques, such as longitudinal distribution of tensile strain and dopant concentration, and we expect better SBS suppression when this method is used with those techniques.

Liu, Chi-Hung

428

Environmental Consequences of Invasive Species: Greenhouse Gas Emissions of Insecticide Use and the Role of Biological Control in Reducing Emissions  

PubMed Central

Greenhouse gas emissions associated with pesticide applications against invasive species constitute an environmental cost of species invasions that has remained largely unrecognized. Here we calculate greenhouse gas emissions associated with the invasion of an agricultural pest from Asia to North America. The soybean aphid, Aphis glycines, was first discovered in North America in 2000, and has led to a substantial increase in insecticide use in soybeans. We estimate that the manufacture, transport, and application of insecticides against soybean aphid results in approximately 10.6 kg of carbon dioxide (CO2) equivalent greenhouse gasses being emitted per hectare of soybeans treated. Given the acreage sprayed, this has led to annual emissions of between 6 and 40 million kg of CO2 equivalent greenhouse gasses in the United States since the invasion of soybean aphid, depending on pest population size. Emissions would be higher were it not for the development of a threshold aphid density below which farmers are advised not to spray. Without a threshold, farmers tend to spray preemptively and the threshold allows farmers to take advantage of naturally occurring biological control of the soybean aphid, which can be substantial. We find that adoption of the soybean aphid economic threshold can lead to emission reductions of approximately 300 million kg of CO2 equivalent greenhouse gases per year in the United States. Previous studies have documented that biological control agents such as lady beetles are capable of suppressing aphid densities below this threshold in over half of the soybean acreage in the U.S. Given the acreages involved this suggests that biological control results in annual emission reductions of over 200 million kg of CO2 equivalents. These analyses show how interactions between invasive species and organisms that suppress them can interact to affect greenhouse gas emissions. PMID:23977273

Heimpel, George E.; Yang, Yi; Hill, Jason D.; Ragsdale, David W.

2013-01-01

429

CONTROL TECHNOLOGIES FOR FUGITIVE VOC EMISSIONS FROM CHEMICAL PROCESSES  

EPA Science Inventory

This handbook contains information concerning volatile organic compound (VOC) emissions from the synthetic organic chemicals manufacturing industry (SOCMI), petroleum refineries, on-shore natural gas processing plants, polymer manufacturing plants, benzene from particular equipme...

430

CONTROL OF EMISSIONS FROM RESIDENTIAL WOOD BURNING BY COMBUSTION MODIFICATION  

EPA Science Inventory

The report describes an exploratory study of factors contributing to atmospheric emissions from residential wood-fired combustion equipment. Three commercial appliances were operated with both normal and modified designs, providing different burning modes: updraft with a grate, u...

431

Gaseous and particulate emission profiles during controlled rice straw burning  

NASA Astrophysics Data System (ADS)

Burning of rice straw can emit considerable amounts of atmospheric pollutants. We evaluated the effect of rice straw moisture content (5%, 10%, and 20%) on the emission of carbon dioxide (CO2) and on the organic and inorganic constituents of released particulate matter (PM): dioxins, heavy metals, and polycyclic aromatic hydrocarbons (PAHs). Four burning tests were conducted per moisture treatment using the open chamber method. Additionally, combustion characteristics, including burning stages, durations, temperature, and relative humidity, were recorded. Burning tests showed flaming and smoldering stages were significantly longer in 20% moisture treatment (P < 0.05) compared with the rest. The amount of burned straw and ashes decreased with increasing straw moisture content (P < 0.001). Carbon dioxide was the main product obtained during combustion with emission values ranging from 692 g CO2 kg dry straw-1 (10% moisture content) to 835 g CO2 kg dry straw-1 (20% moisture content). Emission factors for PM were the highest in 20% moisture treatment (P < 0.005). Fine PM (PM2.5) accounted for more than 60% of total PM mass. Emission factors for dioxins increased with straw moisture content, being the highest in 20% moisture treatment, although showing a wide variability among burning tests (P > 0.05). Emissions factors for heavy metals were low and similar among moisture treatments (P > 0.05). Emission factors for individual PAHs were generally higher in 20% moisture treatment. Overall, emission factors of atmospheric pollutants measured in our study were higher in the 20% moisture content. This difference could be attributed to the incomplete combustion at higher levels of rice straw moisture content. According to our results, rice straw burning should be done after straw drying and under minimal moisture conditions to lower pollutant emission levels.

Sanchis, E.; Ferrer, M.; Calvet, S.; Coscollà, C.; Yusà, V.; Cambra-López, M.

2014-12-01

432

Evolving technological systems for diesel engine emission control: balancing GHG and local emissions  

Microsoft Academic Search

The Triad—North America, Japan and Europe—now addresses diesel vehicle emissions by requiring 40–80% reductions from new heavy-duty\\u000a trucks and passenger car diesels. The requirements imply introduction of new technology and fuels stepwise during 2005–2012\\u000a that will leave emissions from new diesel vehicles on par with the levels of gasoline passenger cars. This paper studies the\\u000a recent development of diesel engine

David Bauner; Staffan Laestadius; Norimasa Iida

2009-01-01

433

Spontaneous and induced emission of XeCl* excimer molecules under pumping of Xe - CCl4 and Ar - Xe - CCl4 gas mixtures with a low CCl4 content by fast electrons and uranium fission fragments  

NASA Astrophysics Data System (ADS)

The spontaneous and induced emission of XeCl* excimer molecules upon excitation of Xe - CCl4 and Ar - Xe - CCl4 gas mixtures with a low CCl4 content by high-energy charged particles [a pulsed high-energy electron beam and products of neutron nuclear reaction 235U(n, f)] has been experimentally studied. The electron energy was 150 keV, and the pump current pulse duration and amplitude were 5 ns and 5 A, respectively. The energy of fission fragments did not exceed 100 MeV, the duration of the neutron pump pulse was 200 ?s, and the specific power contribution to the gas was about 300 W cm-3. Electron beam pumping in a cell 4 cm long with a cavity having an output mirror transmittance of 2.7% gives rise to lasing on the B ? X transition in the XeCl* molecule (? = 308 nm) with a gain ? = 0.0085 cm-1 and fluorescence efficiency ? ? 10%. Pumping by fission fragments in a 250-cm-long cell with a cavity formed by a highly reflecting mirror and a quartz window implements amplified spontaneous emission (ASE) with an output power of 40 - 50 kW sr-1 and a base ASE pulse duration of ~200 ms.

Mis'kevich, A. I.; Guo, J.; Dyuzhov, Yu A.

2013-11-01

434

Spontaneous Emission of a Two-Level Static Atom Coupling with Electromagnetic Vacuum Fluctuations Outside a High-Dimensional Einstein Gauss–Bonnet Black Hole  

NASA Astrophysics Data System (ADS)

Using the generalized formalism of Dalibard, Dupont–Roc and Cohen–Tannoudji we investigate the spontaneous excitation of a static atom interacting with electromagnetic vacuum fluctuations outside an Einstein Gauss–Bonnet black hole in d-dimensions. It shows that spontaneous excitation does not occur in a Boulware vacuum, while exists in an Unruh vacuum and Hartle–Hawking vacuum. As to the total rate of change of the atomic energy, it does not receive the contribution from the coupling constant of the Gauss–Bonnet term at spatial infinity only the dimensional parameter has the contribution to it. Near the event horizon, both the coupling constant and the dimension p contribute to the total rate of change of the atomic energy in all three kinds of vacuum. We discuss the contribution of the coupling constant and dimensional factor to the results in three different kinds of spacetime lastly.

Zhang, Ming; Yang, Zhan-Ying; Yue, Rui-Hong

2014-10-01

435

Emission characteristics and control efficiency of acidic and basic gases and aerosols from packed towers  

NASA Astrophysics Data System (ADS)

Large amount of acidic liquids, such as H 2SO 4, HF, HCl and HNO 3, and basic NH 3 liquid are used in high-tech industries in cleaning and etching processes in the Hsinchu Science-Based Industrial Park in Taiwan. The industries use packed towers (or scrubbers) to control emission of these inorganic pollutants, in which acidic gases but not particles are regulated by the Taiwan EPA's strict emission standard for semiconductor industry. To understand whether the emission standard is met and to investigate the emission rates, emission profiles, emission factors, and control efficiencies of various gaseous/aerosol species, measurement of pollutants before and after the packed towers was conducted using a sensitive porous metal sampler during January 2001 to February 2003. Results show that the pollutants are mainly in the gaseous phase, and the control efficiency of pollutants is low and variable when the inlet concentration is low. In addition to the control efficiency data, emission factors before the control device for various gas and particle species have also been developed for estimating the emission rates.

Tsai, Chuen-Jinn; Chang, Chang-Tso; Liu, Tsing-Wei; Huang, Chun-Chao; Chien, Chih-Liang; Chein, Hung Min

436

ENSO controls on dust emissions from large ephemeral lakes  

NASA Astrophysics Data System (ADS)

Mineral aerosols (desert dust) interact with global climate and biogeochemistry. Recent research has suggested that the most significant sources of mineral aerosols are associated with topographic lows in drylands that contain contemporary or old ephemeral lakes, and that complex relationships may exist between surface water, hydrology and these desert dust sources. Most mineral aerosol emissions are observed in the northern hemisphere. Here, the identification of key processes acting within the dust source areas using remote sensing is far from straightforward; and currently inconclusive. This has implications for the generation and testing of dust emission models, and for estimating the relative impacts of natural and anthropogenic dust emission processes. In the southern hemisphere, dust emissions from a range of relatively discrete dust sources, centred on contemporary ephemeral lake basins, may provide an opportunity to constrain some of the emission processes and forcing mechanisms at regional scales. Research here involves the study of processes occurring within the dust source areas of southern Africa, southern America, and Australia. Using time-series of monthly TOMS, AVHRR, gridded climate data, surface climate data, and occasional gauged hydrological inputs, the relationship between dust emissions and surface processes have been investigated for a 20-year period (1982-2002) for large ephemeral lakes. The sources investigated were: (i) Etosha Pan, Namibia (location: 16oE, 18oS: area c.4800km2), (ii) The Makgadikgadi Pans, Botswana (location: 21oS, 26oE; area c.4480km2 (Ntwetwe Pan) and c.1116 km2 (Sua pan), (iii) Lake Eyre, Australia (location 27oS 137oE, area c.9300km2) and (iv) Salar de Uyuni (area c.10580km2) and Salar de Coipasa (area c.2220km2) located at approx. 20oS 67oW in Bolivia. For most of these lakes, findings show a significant relationship between anomalies in TOMS AI and the timing/extent of inundation; confirming a link between each ephemeral lake basin and the TOMS dust plumes, and giving a clear indication of dust emission processes acting in each basin. In particular, significant inflows and inundation events in most of these basins are associated with La Nina episodes, and these events lead to significant negative TOMS anomalies over long time-periods; primarily due to raised groundwater levels and increased vegetation abundance. El Nino periods generally equate to periods of low inflows, a reduction in groundwater level, and greater likelihood of positive TOMS anomalies. This research suggests that the large southern hemisphere ephemeral lake basins are significant regional dust sources, and that an appreciation of their hydrological dynamics is essential for understanding/modelling global dust emissions from drylands.

Bryant, R. G.; Mahowald, N. M.; Eckardt, F.; Ross, S.

2004-12-01

437

Factors controlling the occurrence of the Jovian decametric radio emission  

NASA Astrophysics Data System (ADS)

The statistical analysis of occurrence of Io-related Jovian decametric radio (DAM) emission shows that the occurrence of the emission increase when Io is in the longitude range 120° -300° (Io's longitude in the frame III). Another result of the statistical analysis is a predominance of DAM emission sources in the northern hemisphere of Jupiter. We show that these phenomena are the result of the joint effect of two factors - the variation of the efficiency of particle acceleration in the ionosphere of the satellite Io and the variation of the broadening of the angular spectrum of accelerated particles during their pass through Io's plasma torus depending on Io's longitude. The planes of the rotational, magnetic and centrifugal (for Io's torus) equators do not coincide. As a result the magnetic field near the satellite Io, which determines the accelerated particle efficiency [1], changes periodically. The most effective acceleration takes place in the longitude range 120° ? ?Io ? 300° . Just in this longitude range the satellite Io appears to be "screened" by the plasma torus of the southern hemisphere. Making their way to the southern hemisphere, the particles are scattered in the torus plasma 2° , within which they and withdrawn from a narrow range of pitch-angles ??0 can reach the southern hemisphere [2]. Therefore in the mentioned longitude range northern sources of DAM emission should be concentrated. At the same time in the longitude range, where the "screening" effect of the plasma torus in the southern direction is negligible, the efficiency of the accelerated mechanism is essentially smaller due to the decrease of the magnetic field near Io. Therefore the southern sources turn to be weaker and are located mainly outside the longitude range, where the emission from the northern sources predominates. Since the emission from the northern sources predominates, the active longitudes are determined basically by this emission and are in the range 120° ? ?Io ? 300° . The distribution of accelerated electron fluxes near the southern foot of the magnetic tube of Io coincides well with the distribution of the occurrence of the left-hand polarized emission from the source Io-C. References 1. Zaitsev V. V., Shaposhnikov V. E., Rucker H. O. 2003, Astronomy Report, 80, 761. 2. Zaitsev V. V., Shaposhnikov V. E., Rucker H. O. 2006, Astronomy and Astrophysics, in press.

Zaitsev, V. V.; Shaposhnikov, V. E.; Rucker, H. O.

438

40 CFR 266.107 - Standards to control hydrogen chloride (HCl) and chlorine gas (Cl2) emissions.  

Code of Federal Regulations, 2011 CFR

... Standards to control hydrogen chloride (HCl) and chlorine gas (Cl2) emissions... Standards to control hydrogen chloride (HCl) and chlorine gas (Cl2) emissions...must comply with the hydrogen chloride (HCl)...

2011-07-01

439