Gas Turbine Aerodynamics Improvement Via a Design of Intelligent Fractional Control

Gas turbines are complex processes characterized by the instability and uncertainty of various sources. The range of useful operating in an axial compressor which is part of a turbine gas is limited by aerodynamic instabilities that are surge and rotating stall. This paper presents two intelligent fractional order sliding mode controllers. At first, a robust sliding fractional surface form is proposed to deal with hazardous phenomena which limit compression systems performance, and speed transitions, which can lead to temporary stall development, pressure drop at the output, degrade the effective operation of compressors and consequently gas turbines. Second, to reduce the chattering/fluctuation in control, a fuzzy logic and finite time criterion are used as switching control at the reaching phase in the sliding mode control. Additionally, the controller gains are obtained by offline multi-objective Particle swarm optimization (MOPSO) search. Finally, the surge and rotating stall of a Variable Speed Axial Compressor (VSAC) in a gas turbine are investigated under the system nonlinearities and also in presence of an external disturbance and perturbations. The simulation results signify the performance of the two MOPSO-based fractional sliding mode controllers.

On mineral dust hygroscopicity

<p>Despite its importance, hygroscopicity of mineral dust aerosol remains highly uncertain. In this work, we investigated water adsorption and hygroscopicity of different mineral dust samples at 25 ∘C, via measurement of sample mass at different relative humidity (RH, up to 90 %) using a vapor sorption analyzer. Mineral dust samples examined (21 in total) included seven authentic mineral dust samples from different regions in the world and 14 major minerals contained in mineral dust aerosol. At 90 % RH, the mass ratios of adsorbed water to the dry mineral ranged from 0.0011 to 0.3080, largely depending on the BET surface areas of mineral dust samples. The fractional surface coverages of adsorbed water were determined to vary between 1.26 and 8.63 at 90 % RH, and it was found that the Frenkel–Halsey–Hill (FHH) adsorption isotherm could describe surface coverages of adsorbed water as a function of RH well, with AFHH and BFHH parameters in the range of 0.15–4.39 and 1.10–1.91, respectively. The comprehensive and robust data obtained would largely improve our knowledge of hygroscopicity of mineral dust aerosol.</p>

On mineral dust aerosol hygroscopicity

Despite its importance, hygroscopicity of mineral dust aerosol remains highly uncertain. In this work, we investigated water adsorption and hygroscopicity of different mineral dust samples at 25 ∘C, via measurement of sample mass at different relative humidity (RH, up to 90 %) using a vapor sorption analyzer. Mineral dust samples examined (21 in total) included seven authentic mineral dust samples from different regions in the world and 14 major minerals contained in mineral dust aerosol. At 90 % RH, the mass ratios of adsorbed water to the dry mineral ranged from 0.0011 to 0.3080, largely depending on the BET surface areas of mineral dust samples. The fractional surface coverages of adsorbed water were determined to vary between 1.26 and 8.63 at 90 % RH, and it was found that the Frenkel–Halsey–Hill (FHH) adsorption isotherm could describe surface coverages of adsorbed water as a function of RH well, with AFHH and BFHH parameters in the range of 0.15–4.39 and 1.10–1.91, respectively. The comprehensive and robust data obtained would largely improve our knowledge of hygroscopicity of mineral dust aerosol.

The influence of fractional surface coverage on the core–core separation in ordered monolayers of thiol-ligated Au nanoparticles

This study examines the way in which fractional surface coverage on a nanoparticle surface affects nanoparticle interactions and the long-range order of Langmuir monolayers.

Coexpression of RTI40 with alveolar epithelial type II cell proteins in lungs following injury: identification of alveolar intermediate cell types

Injured alveolar epithelial type (AT) I cells are replaced following the proliferation and transformation of ATII cells to new ATI cells. RTI40 is an ATI cell-specific protein required for normal lung development. We hypothesized that intermediate cell types in the ATII-to-ATI cell transformation would coexpress RTI40 and ATII cell-selective proteins. To test this hypothesis, we used a rat model of Staphylococcus aureus-induced acute lung injury and a panel of ATI and ATII cell-specific and -selective antibodies. S. aureus induced an acute inflammatory reaction that was resolving by day 3 postinoculation. At day 3 postinoculation, the alveolar wall was thickened secondary to ATII cell hyperplasia. With the use of confocal microscopy, there was a fivefold increase in the fractional surface area of alveolar walls stained with ATII cell membrane proteins (RTII70 and MMC4) and a decrease in the fractional surface area associated with RTI40-expressing cells. S. aureus-treated lungs also contained unique cell types that coexpressed the RTI40 and ATII markers RTI40/MMC4/RTII70- and RTI40/MMC4-positive cells. These cells were not observed in control lungs. RTI40/MMC4-positive cells were also found in cultured ATII cells before they transformed to an ATI-like phenotype. Our data suggest that RTI40/MMC4/RTII70- and RTI40/MMC4-positive cells are intermediates in the ATII-to-ATI cell transformation. These data also suggest that the coexpression of RTI40 with ATII cell proteins may be used to identify and investigate ATII cell transdifferentiation to ATI cells following injury.