ALBERT

Description: A series of CuO/Ce 0.6 Zr 0.4 O 2 catalysts doped with rare earth (Y, La) oxides and transition metal (Fe, Co, Ni) promoters were synthesized by the coprecipitation method. The effects of the additive type and content on the structure, redox properties, and water-gas shift (WGS) catalytic activity were investigated in detail by X-ray diffraction, N 2 physisorption, scanning electron microscopy, energy-dispersive X-ray spectroscopy, H 2 temperature-programmed reduction, and Raman spectroscopy. The catalytic activity was tested in terms of CO in H 2 -rich coal-derived synthesis gas, which simulated the actual gas composition of an integrated gasification combined cycle system. The experimental results revealed the beneficial role of doping with 3 wt % Fe in enhancing the catalytic performance by increasing the oxygen storage and mobility capacity, the reducibility, and the synergistic interaction between copper oxide and ceria-zirconia. The metal-support interactions within ceria-based catalysts are important in WGS reactions. Microporous catalysts were therefore doped with rare earth oxides or transition metal promoters and catalytic activity was tested. Both additive type and content can influence the catalytic activity by affecting oxygen vacancies, reducibility, and the interaction between copper oxide and support.

Description: [1]  We have measured interseismic deformation across the Ashkabad strike-slip fault using 13 Envisat interferograms covering a total effective timespan of ~30 years. Atmospheric contributions to phase delay are significant and variable due to the close proximity of the Caspian Sea. In order to retrieve the pattern of strain accumulation, we show it is necessary to use data from Envisat's Medium Resolution Imaging Spectrometer (MERIS) instrument, as well numerical weather model outputs from the European Centre for Medium-Range Weather Forecasting (ECMWF), to correct interferograms for differences in water vapour and atmospheric pressure respectively. This has enabled us to robustly estimate the slip rate and locking depth for the Ashkabad fault using a simple elastic dislocation model. Our data are consistent with a slip rate of 5–12 mm/yr below a locking depth of 5.5–17 km for the Ashkabad fault, and synthetic tests support the magnitude of the uncertainties on these estimates. Our estimate of slip rate is 1.25–6 times higher than some previous geodetic estimates, with implications for both seismic hazard and regional tectonics, in particular supporting fast relative motion between the South Caspian Block and Eurasia. This result reinforces the importance of correcting for atmospheric contributions to interferometric phase for small strain measurements. We also attempt to validate a recent method for atmospheric correction based on ECMWF ERA-Interim model outputs alone and find that this technique does not work satisfactorily for this region when compared to the independent MERIS estimates.

Description: The micro-particle image velocimetry (micro-PIV) is a quantitative full field technique for the velocity measurement for flows in microfluidics. The flow fields of both Newtonian and non-Newtonian fluids in microchannels were investigated by micro-PIV. The velocity profiles in various PMMA square microchannels were measured. Different concentrations of various polyacrylamide (PAAm) aqueous solutions were used as non-Newtonian fluids. Two viscous Newtonian fluids were also employed to serve as reference, in particular to validate a lattice Boltzmann (LB) simulation. The results show that satisfactory flow measurements could be realized by the micro-PIV technique. The experimental velocity profile compares favourably with the LB simulation and an approximate solution. The experimentally measured velocity profile can lead to the quantification of the flow index of non-Newtonian fluids as an in-line rheological characterisation.

Description: Waves and current processes, both surface and near-bed were simulated for major storms on the Grand Banks of Newfoundland using integrated wave, 3D tidal and ocean current models. Most storms track southwest to northeast and pass to the north or northwest of the Grand Banks. Significant wave heights can reach up to ∼14 m and are predominantly to the northeast at the peak of storms. Extreme surface currents reach approximately 1 m s −1 and are largely to the southeast. The strongest bottom currents, up to 0.8 m s −1 , occur on St. Pierre Bank and are dominantly to the south and southeast. While wave height and wind-driven current generally increase with wind speed, factors such as storm paths, the relative location of the storm center at the storm peak, and storm translation speed also affect waves and currents. Surface and near-bed wind-driven currents both rotate clockwise and decrease in strength as the storm traverses the Grand Banks. While the spatial variability of the storm impact on surface currents is relatively small, bottom currents show significant spatial variation of magnitude and direction as well as timing of peak current conditions. These spatial variations are controlled by the changes of bathymetry and mixed layer depth over the model domain. The storm-generated currents can be 7 to 10 times stronger than the background mean currents. These strong currents interact with wave oscillatory flows to produce shear velocities up to 15 cm s −1 and cause wide occurrences of strong sediment transport over nearly the entire Grand Banks. This article is protected by copyright. All rights reserved.

Description: The formation of the world-class, high-grade unconformity-related uranium deposits in the Athabasca Basin (Canada) requires circulation of large amounts of fluids, the mechanisms for which are still not well understood. Recent studies advocate thermal convection as a possible driving force for the fluid flow related to uranium mineralization; however, little is known regarding how basement faults, which are spatially associated with most unconformity-related uranium deposits, influence fluid convection and how this may affect the localization of mineralization. This study addresses these questions through simulations of thermal convection with various configurations of basement faults using the FLAC3D software. Modelling results indicate that the location, spacing, orientation and thermal conductivities of basement faults influence the size and location of thermally driven fluid convection. In a model with a single isolated fault, the fault coincides with an upwelling plume and the dip angle of the fault does not affect the fluid flow pattern; when the fault is moved laterally, the upwelling plume shifts accordingly. In the case of two vertical faults, the faults may either coincide with upwelling flow between two convection cells or be located below individual convection cells, depending on fault spacing. In the latter case, fluid may flow into and out of individual fault zones. Similar results were also obtained for models with two nonvertical (i.e. dipping) faults. Convective flow can penetrate the uppermost basement when the permeability is less than two orders of magnitude lower than that of the overlying sandstone. In this case, the basement faults not only can control the location of ascending flow, but also can passively act as fluid conduits of either flow from the basin into the basement (ingress), or flow from the basement into the basin (egress), depending on their thermal conductivities and relative locations in the models.

Description: Fluidized-bed spray granulation is used to produce porous granular particles from suspensions, solutions, and melts. In this work, the adapted two-fluid model approach is used to simulate the fluid dynamics in the fluidized bed, and a simplified direct quadrature method of moments is adopted to mimic the full particle size distribution. The size-dependent growth kinetics is obtained by computational fluid dynamics simulation for short process times from the modeling of drop deposition on the particles. This kinetics is used in the population balance equation to predict the evolution of the full particle size distribution for long process times. Such a multiscale approach allows for a description of continuous granulation processes. In this investigation, a coupled computational fluid dynamics (CFD) and population balance equation (PBE) approach is used to simulate the growth of polydisperse particles in a fluidized-bed spray granulation process. The growth kinetics is used in the PBE to solve the development of the particle size distribution for a long process time without considering the fluid dynamics.

Description: The momentum budget of the migrating diurnal tide (DW1) at the vernal equinox is studied using the Whole Atmosphere Community Climate Model, version 4 (WACCM4). Classical tidal theory provides an appropriate first-order prediction of the DW1 structure, while gravity wave (GW) forcing and advection are the two most dominant terms in the momentum equation that account for the discrepancies between classical tidal theory and the calculation based on the full primitive equations. It differs from the conclusion by McLandress (2002a) that the parameterized GW effect is substantially weaker than advection terms based on the Canadian Middle Atmosphere Model (CMAM). In the region where DW1 maintains a large amplitude, GW forcing in the wave breaking region always damps DW1 and advances its phase. The linear advection largely determined by the latitudinal shear of the zonal mean zonal wind makes a dominant contribution to the phase change of DW1 in the zonal wind compared to the GW forcing and nonlinear advection. However, nonlinear advection is more important than GW forcing and linear advection in modulating the amplitude and phase of DW1 in the meridional wind. The DW1 amplitudes in temperature and winds are smaller than the TIMED observations, suggesting that GW forcing is overestimated in the WACCM4 and results in a large damping of DW1.

Description: Many drought indices were proposed to describe drought characteristics, but only few had considered environmental changes. In an attempt to incorporate climate change into meteorological drought index, a nonstationary Gamma distribution with climate indices as covariates was developed for fitting precipitation data, and then used for calculating a Nonstationary Standardized Precipitation Index (NSPI) in this study. The performances of the NSPI were compared with those of the traditional Standardized Precipitation Index (SPI), showing that the NSPI capable of taking climate variations into account is more robust than the traditional SPI. Focusing on the Luanhe River basin, historical drought events were described and assessed based on the NSPI and traditional SPI. Moreover, drought characteristics, including drought frequency, peak, duration and magnitude, were calculated by using the two indices. The results in this study indicated that NSPI using climate indices as covariates could capture drought characteristics in the Luanhe River basin, and this new drought index provides a new concept for constructing the drought index that can effectively adapt to a changing environment.

Description: The 3rd September 2010 Mw 7.1 Darfield and 21st February 2011 Mw 6.3 Christchurch (New Zealand) earthquakes occurred on previously unknown faults. We use InSAR ground displacements, SAR amplitude offsets, field mapping, aerial photographs, satellite optical imagery, a LiDAR DEM and teleseismic body-wave modeling to constrain the pattern of faulting in these earthquakes. The InSAR measurements reveal slip on multiple strike-slip segments and secondary reverse faults associated with the Darfield main shock. Fault orientations are consistent with those expected from the GPS-derived strain field. The InSAR line-of-sight displacement field indicates the main fault rupture is about 45 km long, and is confined largely to the upper 10 km of the crust. Slip on the individual fault segments of up to 8 m at 4 km depth indicate stress drops of 6–10 MPa. In each event, rupture initiated on a reverse fault segment, before continuing onto a strike-slip segment. The non-double couple seismological moment tensors for each event are matched well by the sum of double couple equivalent moment tensors for fault slip determined by InSAR. The slip distributions derived from InSAR observations of both the Darfield and Christchurch events show a 15-km-long gap in fault slip south-west of Christchurch, which may present a continuing seismic hazard if a further unknown fault structure of significant size should exist there.

Description: Abstract One second in‐situ measurements of CO and CO2 mole fractions were made aboard the NASA DC‐8 aircraft during the 2016 KORUS‐AQ joint air quality and atmospheric chemistry field campaign in South Korea. The ratio of CO to CO2 enhancement is used to characterize regional combustion source signatures. Calculations of the ∆CO/∆CO2 ratio were made with a short duration rolling window (60 seconds), filtered by the coefficient of determination (R2), and plotted as distributions to characterize air masses measured from the aircraft during the campaign. The KORUS‐AQ sampling domain was divided into analysis regions to facilitate the analysis. Over Seoul, the boundary layer shows a low‐ratio signature in the ∆CO/∆CO2 ratios, with more than 50% of the correlated slopes in the boundary layer falling below 1 % ∆CO/∆CO2, and 80% of the slopes between 0 – 2% ∆CO/∆CO2. However, this behavior changes to a larger ratio distribution at higher altitudes. The West Sea receptor region was divided into three analysis sectors, by meteorological regime, and used in conjunction with measurements collected over China during the KORUS‐AQ campaign time period to characterize the Chinese ∆CO/∆CO2 ratio signature. Chinese‐type emissions have a slope distribution that is shifted to higher ratios and broadened compared to measurements over Seoul, with the bulk of the measurements between 2 – 4% ∆CO/∆CO2, with few negative slopes. The measured ratio trends over South Korea are consistent with inventoried CO and CO2 emissions.