Peak Emission Rate Research Articles

INFLUENCE OF ASH AMENDMENT ON ODOR EMISSIONS AND AEROBIC BIODEGRADATION OF BIOSOLIDS MIXES

Controlled incubation studies (120 h at 37.C) using a mixture of 32% biosolids and 68% wood shavings (dry weight basis) amended with ash (biosolids blend:ash = 1:0.3, dry weight) were conducted to evaluate the influence of ash on odor emissions and biological activity of the mix. Three coal fly ashes (high carbon, medium carbon, and low carbon), wood fly ash, and activated carbon were evaluated against a no–ash control. The concentration of dimethyl disulfide (DMDS), dimethyl sulfide (DMS), and CO2 in the exhaust gas was measured at 0, 24, 48, 72, 96, and 120 h. Data were used to calculate emission rates and cumulative emission, which were analyzed to determine treatment differences. Results show that peak emission rates of DMDS and DMS in the no–ash control treatment were 41.9 and 1.89 .g/kg/min, respectively, while 120–h cumulative emissions were 189.95 and 11.39 mg/kg, respectively. Amendments reduced peak DMDS emission rates in all treatments. Percent reductions were highest in activated carbon and wood fly ash at 90% and 63%, respectively. For the three coal fly ashes, percent reduction ranged from 18% to 24%. Percent reduction in 120–h cumulative DMDS emission for high carbon, medium carbon, and low carbon coal ashes; wood ash; and activated carbon compared to the no–ash control were 41%, 29%, 53%, 59%, and 89%, respectively. In contrast, the peak emission rate for DMS increased while using two coal ash treatments and the wood fly ash treatment, where percent increases were 54% to 122% compared to the control. There was no difference in biological activity between treatments based on maximum CO2 production rates, which were in the range of 34 to 42 mg/kg/min. These rates correspond to 2.04 to 2.52 mg/g/hr of CO2 production, representing high biological activity.

Identification of the Dominant Electron Deep Trap in a-Si:H: A Critical Test of the Defect Pool vs. Defect Relaxation Pictures

ABSTRACTModulated photocurrent (MPC) measurements in intrinsic a-Si:H reveal a prominent band of electron deep traps with a thermal emission energy near 0.6eV. We have identified this defect band by directly comparing MPC and ESR spectra for both an intrinsic and a lightly n-type doped sample for a various metastable states such that the Fermi level, EF, ranges from less than 0.5eV to more than 0.7eV below Ec. This comparsion unambiguously demonstrates that the MPC band arises from the Do charge state of the defects (specifically, the D−&Do transition). This identification is also confirmed when the quasi-Fermi level is varied by the application of light bias even though the peak emission rate from the MPC defect band is changed by more than a factor of 100. These observations specifically rule out the possibility of large populations of charged defects in intrinsic samples predicted by proponents of the defect pool model. Instead, observed behaviors have a natural explanation in terms of a defect relaxation process.

A model for 5577Å and 8446Å atomic oxygen dayglow emission at midaltitudes

In this paper we present the results of volume emission rate profiles of 5577Å and 8446Å dayglow emission at midlatitudes. A model is developed by taking into account the variation in solar EUV flux as a function of solar activity and uses recent cross section data. The thermospheric peak emission rate ratio V(5577)x V(8446) is studied as a function of local time at midlatitudes. This ratio is found maximum at local noon time. The ratio is comparetively larger in the afternoon sector than the forenoon sector. In addition, the sensitivity of emission rate (for both emission) to atomic oxygen composition is studied by varying the density of atomic oxygen in the model. At local noon time, when the atomic oxygen density is reduced to half in the model, the ratio V(5577) V(8446) is about 6.0 and this ratio approaches to about 2.0 if the atomic oxygen density is made double. The photoelectron flux is found more sensitive to atomic oxygen density.

Correlations between the mesospheric O(1S) emission peak intensity and height, and temperature at 98 km using WINDII data

Data from O(1S) emissions measured by the WIND Imaging Interferometer (WINDII) on the UARS spacecraft for two days in the January/February 1992 time period are used to analyse the behaviour of the oxygen green-line peak in the mesosphere. Correlations between the peak emission and height are observed for the night-time measurements but not for the day-time measurements. Extremes in the peak emission rate and height are compared to the temperature field at 98 km. It is found that when the emission rate is high, the height of the peak is low and the temperature is high and vice versa. This is suggestive of what might occur if the motions associated with these extrema were quasi-adiabiatic and the oxygen mixing ratio conserved.

Single Molecule Spectroscopy in Shpol'skii Matrices

Optical detection and spectroscopy of single molecules has recently been achieved in solids at very low temperature. Until now only three host-guest combinations have fulfilled the stringent requirements for high-resolution single-molecule spectra. A large absorption cross section has to be paired with high fluorescence quantum yield, high photochemical stability, as well as the absence of any significant shelving in a bottleneck state. The photophysical properties of the single fluorescent molecule are strongly influenced by its 'nano-environment'. Here we report the properties of a new system: terrylene in the Shpol'skii matrix hexadecane. In this system a peak emission rate more than 107 photons/s is achieved. It is expected that such a Shpol'skii system is a prototype of a new class of materials which allow single-molecule spectra to be easily recorded.

Double-Peak Emission Rate Spectrum of DX-Centers in AlxGa1-xAs

Emission rate spectra S(λ) of the DX-centers in AlxGa1-xAs were studied for dopants, such as Te, Sn, Si and Se, using the SADLTS (spectral analysis of deep level transient spectroscopy) method. The double peak emission rate spectra were observed for these DX-centers in AlxGa1-xAs at around x=0.5 of Al mole fraction. The band effect (crossover of L-band and \\varGamma-band) is the dominant contribution to the rather broadened spectra of DX-centers appearing in the conventional DLTS.

Rocket measurements of O2 atmospheric and OH Meinel Bands in the airglow

Altitude distributions of the (0, 0) 7619‐Å band of O2 atmospheric system (b¹Σg+ ‐, X3Σg−) and the (7, 2) 6863‐Å band of OH (X²Π) in the night airglow emissions were measured at 31°N latitude. In spite of the different seasons and local times of the observations, all three measurements presented the peak emission rate occurring at an altitude of 94±1 km for the O2 band and at 90±2 km for the OH band. The former emitting altitude is in basic agreement with the atomic oxygen density profile as measured by using an O I 1300‐Å resonance lamp, but the latter is considerably higher than expected from relevant theoretical models. After examining various possible causes for this discrepancy, it seems that the continuum airglow may contaminate our observations of the OH airglow.