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Real-time mass spectra of the non-refractory species in submicron aerosol particles were recorded in a tropical rainforest in the central Amazon Basin during the wet season from February to March 2008, as a part of the Amazonian Aerosol Characterization Experiment (AMAZE-08). Organic material accounted on average for more than 80% of the non-refractory submicron particle mass concentrations during the period of measurements. There was insufficient ammonium to neutralize sulfate. In this acidic, isoprene-rich, HO2-dominant environment, positive-matrix factorization of the time series of particle mass spectra identified four statistical factors to account for the 99% of the variance in the signal intensities of the organic constituents. The first factor was identified as associated with regional and local pollution and labeled "HOA" for its hydrocarbon-like characteristics. A second factor was associated with long-range transport and labeled "OOA-1" for its oxygenated characteristics. A third factor, labeled "OOA-2," was implicated as associated with the reactive uptake of isoprene oxidation products, especially of epoxydiols to acidic haze, fog, or cloud droplets. A fourth factor, labeled "OOA-3," was consistent with an association with the fresh production of secondary organic material (SOM) by the mechanism of gas-phase oxidation of biogenic volatile organic precursors followed by gas-to-particle conversion of the oxidation products. The suffixes 1, 2, and 3 on the OOA labels signify ordinal ranking with respect to the extent of oxidation represented by the factor. The process of aqueous-phase oxidation of water-soluble products of gas-phase photochemistry might also have been associated to some extent with the OOA-2 factor. The campaign-average factor loadings had a ratio of 1.4:1 for OOA-2 : OOA-3, suggesting the comparable importance of particle-phase compared to gas-phase pathways for the production of SOM during the study period.

Ground-based measurements of aerosol and trace gases were conducted at a rural site in Beijing in the summer of 2006 as a part of the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing 2006). The size-resolved chemical composition of submicron aerosol was measured using an Aerodyne quadrupole aerosol mass spectrometer (AMS). The data obtained from 15 August to 10 September 2006 are presented. Meteorological analysis shows that the measurement period can be characterized as a cycle of low wind speed periods over the course of a few days (stagnant periods) followed by rapid advection of clean air from the north/northwest mostly due to passage of a midlatitude cyclone. Mass concentrations of total measured aerosol with diameters less than 1 μm. (total. PM1), which is defined as the sum of elemental carbon and nonrefractory components measured by the AMS, were highly variable, ranging from. ∼2 to ∼100 μm-3, Large variability of the PM1 composition and drastic changes in the sulfate (SO 2-4) size distribution were observed to be associated with the cycle of stagnant periods and advection of clean air, indicating that both chemical and physical properties of aerosols were significantly altered on a time scale of a few days. We have found the dominance of organic aerosol at lower total PM1 mass loadings and that of SO2-4 at higher mass loadings, which may have important implications for the PM control strategy in Beijing. Possible factors affecting the evolution of the mass concentration and size distribution of SO2-4 are discussed. Copyright 2009 by the American Geophysical Union.

Air-gapped iron-cores are widely used for power reactors. Eddy currents are induced in silicon steel sheets due to fringing flux, and this causes local overheating. In order to avoid local heating and to design reactors with high efficiency, the analysis and experiments for evaluating local losses in the core block of the reactor are necessary. In this paper, the modeling of laminated core for practical and accurate analysis is investigated. The number of elements can be reduced by classifying the analyzed region in terms of the amount of fringing flux penetration. The eddy-current losses due to fringing flux are examined using three-dimensional finite-element method and experiments. New concepts for optimal designing of slits are shown. Index Terms--Eddy-current loss, finite-element method, reactor, slit.

We have developed a new time variant pulse processor which is able to adapt the weighting function according to the detector noise characteristics in order to get the best performance from a semiconductor x-ray detecting system. The circuit construction is almost the same as the previously presented trapezoidal filter that was composed of a rectangular prefilter and a gated integrator. The rectangular waveform was formed by adding a differentiated signal and an integration of the differentiated signal with the same ratio. In the new processor it is possible to vary the weighting function continuously by changing the mixing ratio of the differentiated waveform and the integrated one. Noise analysis of the filter has been carried out by using SPICE. This technique is very useful for determining the noise response of a filter simply by the circuit design.

A new time-variant pulse shaping amplifier that is composed of a rectangular prefilter and a gated integrator has been designed for low energy gamma-ray and X-ray spectrometers. A rectangular pulse is formed by adding a differentiated signal and an integration of the differentiated signal. Noise indices of the trapezoidal filter are calculated as a function of the filter and restoration time constant and event interval. By using this filter, the product of the delta noise index and dead time is lower than 5.

The noise indices regarding the rectangular shaper have been calculated. The results indicate that the time constant of BLR should be larger than about 20 times that of the prefilter pulse width. A new feedforward type baseline restorer has been developed for the quasi-rectangular shaper. Its time constant can be designed arbitrarily by the value of its components C and R. Therefor, it is simple to determine the compromising point of delta noise index and tracking ability for baseline fluctuation. The equivalent circuit of this restorer has an attenuator following the CR differentiator. Existence of the attenuator in the equivalent circuit is a difference from the others.

The adhesive-coated nonoriented electromagnetic steel sheet is well known to be effective in realizing high-efficiency, high-power motors with compact size, low noise, and low vibration, as shown in Kaido et al. The authors developed newly adhesive-coated grain-oriented electromagnetic steel sheets. We developed the gapped iron-core-type reactor having a new iron-core structure using this material. By adapting the adhesive-coated grain-oriented electromagnetic steel sheets to the leg of the reactor, the fastening studs of the laminated electromagnetic steel sheets, which are required in a conventional reactor, and the through hole for the fastening studs could be omitted. This enabled us to simplify the structure and reduce the core diameter. On the other hand, we examined the magnetic flux distributions and local loss distributions in the yoke by a detailed magnetic-field analysis to use the oriented electromagnetic steel sheet with boltless construction, and realized the reduction of dimensions and weights due to the increase of magnetic flux density. The reactor developed has such features as smaller size, lighter weight, lower noise level, and low loss. Index Terms--Adhesive-Coated steel sheet, flux distribution, molded core, reactor.

In order to raise the throughput of low-energy X-ray signals appearing in a background of high-energy pulses, a new pulse-processor that measures the rise time of a trapezoidal waveform instead of the peak height has been developed. A rectangular pre-filter and a gated integrator are used to make the wave-shape at the shaper output linear. A rectangular pulse is formed by adding a differentiated step signal and its integration. The rise time of the trapezoidal waveform is inversely proportional to the height of the input step pulse. Therefore, processing time for a high-energy pulse is shorter than that for low-energy one. Consequently, the pile-up loss of the low-energy X-rays is reduced.

We describe a technique, simpler than earlier ones, for using SPICE in the computation of the 1/f, step, and delta noise indices of linear and time-valiant filters. The method is based on obtaining a weighting function from the results of simulation and is demonstrated for triangular and trapezoidal shapers. The results are compared with those obtained by direct calculation. The greatest discrepancies occur when the method is applied to gated integrators, but the errors are probably due to artifacts not related to the basic method described here.