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The balloon-borne Aircore campaign was conducted in Inner Mongolia, China, on June 13 and 14 2018, which detected carbon dioxide (CO2) and carbon monoxide (CO) profiles from surface to 24 km, showing strong positive and negative correlations between 8 km and 10 km on 13 and 14 June, respectively. Backward trajectories, meteorological analyses, and CO2 horizontal distributions were combined to interpret this phenomenon. The results indicated that the source region experienced a stratospheric intrusion and exhibited a large horizontal CO2 gradient; namely, lower CO concentrations corresponded to higher CO2 concentrations and vice versa. The laminar structure with multiple origins resulted in the highly negative correlation between CO2 and CO in the upper troposphere on 14 June. The contribution of stratospheric air mass to the upper troposphere and that of tropospheric air mass to the lower stratosphere were 26.7% and 24.3%, respectively, based on a mass balance approach. Another interesting phenomenon is that CO2 and CO concentrations increased substantially at approximately 8 km on 13 June. An analysis based on the backward trajectory implied that the air mass possibly came from anthropogenic sources. The slope of CO2/CO representing the anthropogenic sources was 87.3 ppm ppm−1. In addition, the CO2 profile showed that there was a large CO2 gradient of 4 ppm km−1 within the boundary layer on 13 June, and this gradient disappeared on 14 June. [ABSTRACT FROM AUTHOR]

CFD simulations of catalytic reactors provide detailed insight into the chemical and physical processes within these devices such as 2D or 3D concentration-, flow- and temperature fields or even 3D pictures of the coverages of the various species on the surface of the catalyst. The validation of CFD models of catalytic reactors is hampered by the lack of experimental data against which the simulation results can be compared. The present work addresses this problem by presenting a critical comparison between CFD simulation results and sub-millimeter resolved species and temperature profiles measured through a reactor employing a catalytic foam monolith. CO oxidation on Pt nanoparticles with narrow size distribution supported on an α -Al 2 O 3 foam was chosen as simple catalytic system with well known microkinetics. To keep uncertainties in the CFD geometry as small as possible, the structure of the foam catalyst was resolved by X-ray microtomography. Simulation parameters and boundary conditions were determined as accurately as possible. The CFD model includes flow, thermal conduction in the struts of the foam, conjugated heat transfer and heat radiation. Catalytic chemistry is incorporated by means of a microkinetic reaction model taken from literature. The comparison of CFD simulation results with high resolution spatial temperature and concentration data allows a critical assessment of strengths and weaknesses of both, the model and the experiment serving as basis for a knowledge-based design of reactors employing catalytic foams or similar random geometries. [ABSTRACT FROM AUTHOR]

Industrial catalytic reactors are made of steel, operate at high temperatures and pressures and contain hazardous chemicals. What happens inside remains hidden. Reactor optimization requires costly trial and error or is based on simplified mathematical models employing more or less accurate transport correlations and reaction kinetics. In the present work a pilot-scale fixed-bed reactor was developed for measuring concentration and temperature profiles for n -butane oxidation to maleic anhydride on vanadyl pyrophosphate catalyst pellets under industrially-relevant conditions. The reactor was equipped with five heating zones. The reactor was modeled by particle-resolved computational fluid dynamics. The catalyst bed was created by discrete element simulation and the result was validated by comparison with experimental radial porosity profiles. Catalytic chemistry was included by a kinetic model of intrinsic reaction rates. Transport resistances and packing deviations were lumped in reaction rate multipliers determined by fitting the model to profiles measured at a uniform reactor wall temperature. Simulation results reveal strong inhomogeneities inside the bed. A hot-spot develops at uniform wall temperature. At this hot-spot temperature differences of 40 K exist on one and the same pellet with negative impact on maleic anhydride selectivity and catalyst lifetime. An optimized wall temperature profile was derived by combining knowledge from the experimental profiles at uniform wall temperature and the CFD results. A gradual increasing temperature was predicted by the model to eliminate the hot-spot and increase integral maleic anhydride selectivity at constant n -butane conversion. This prediction was confirmed by experiment. At 80% n -butane conversion the maleic anhydride selectivity could be improved by 2%. Facing the scale of the process, this improvement translates into significant n -butane savings, reduced CO x emissions and increased revenue. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the possibilities of reconstructing 2D cross sections based on the data of the profile soundings by the transient electromagnetic method with a single ungrounded loop are illustrated on 3D models. It is demonstrated that the data processing of field measurements and recovery of the geoelectrical profile to consist of three main stages: (i) transformation of the measured profile responses into resistivity pseudoprofiles as a function of time and then stitching of the pseudoprofiles as a function of depth, (ii) 1D inversion of responses into a layered 1D profile taking into account the number of layers and their positions determined by the pseudoprofile, and (iii) refinement of the pseudoprofile using 3D inversion with the initial parameters of blocks determined by 1D pseudoprofiles. Transient electromagnetic soundings make it possible to study geological media within a local area at the sounding depth. The structure of the medium outside this area has a little effect on the measurement results. Such localization allows reconstruction of the electrical structure of a 3D medium using 2D profiles with minimal distortion due to the lack of information on the medium outside the profile when measuring transient responses. [ABSTRACT FROM AUTHOR]

Pen pressure is one of the important elements of handwriting and questioned document analysis which is also crucial to recognize forgery. In this paper, we present a new, non-contact, non-destructive, and relatively inexpensive technique to measure the width of the grooves made by the writing. Results demonstrate a clear difference in measured groove widths for varying pen pressure. The effect of passing a written or signed paper in different types of printers has also been studied. A clear decrease of the groove depth was noted when passing the document through a laser printer. An ink jet printer only resulted in a small decrease of the groove depth, while no effect could be detected from a dot matrix printer. [ABSTRACT FROM AUTHOR]

A novel method for in situ profile measurements on rolling contact test specimens has been demonstrated. A chromatic confocal probe was integrated into a twin-disc machine and used for disc profile measurements during periodically interrupted wear tests. The arrangement allowed detailed studies on the progress of the wear during a test without the removal of discs from the tribometer. Data from the interrupted tests was compared with the results of continuous tests. Both types of tests were run with two grades of cast iron dicsc in lubricated contact with steel. The results of this new method were in good agreement with those of a conventional diamond stylus probe method applied before and after the tests. [ABSTRACT FROM AUTHOR]

The present study investigates the validity of a theoretical liquid water content ( LWC ) profile in fog layers currently used for satellite based ground fog detection, with a special focus on the temporal dynamics during fog life cycle. For this purpose, LWC profiles recorded during two different fog events by means of a tethered balloon borne measurement system are presented and discussed. The results indicate a good agreement in trend and gradient between measured and theoretical LWC profiles during the mature stage of the fog life cycle. The profile obtained during the dissipation stage shows less accordance with the theoretical profile. To improve the agreement between theoretical and measured LWC profiles, the evolutionary stages during the fog life cycle should be incorporated. However, the variability within the prenoted measurements points out that more LWC profiles during a great variety of different fog events have to be collected for a well-justified adaptation of the theoretical LWC profile, considering fog life cycle phases in the future. In general, this underlines the existing knowledge gap regarding the vertical distribution of microphysical properties in natural fogs. [ABSTRACT FROM AUTHOR]

In 2000, the European Union adopted the European Water Framework Directive (WFD) (European Commission, 2000). The WFD focuses on increasingly stringent nutrient standards including ultra low nitrogen (< 2.2 mg N-total/L) and phosphorus concentrations (< 0.15 mg total phosphorus/L) in receiving surface waters and in relevant point sources like wastewater treatment plant (WWTP) effluent. Expansion of WWTPs with advanced post-treatment processes, like effluent filtration, is widely proposed to meet possible future effluent discharge standards. When combining biological nitrate-nitrogen and chemical phosphorus removal in one filter, phosphorus limitation in the denitrifying process may occur. This study investigated where in the filter bed and under which conditions phosphorus limitation occurs. Profile measurements for nitrate, nitrite, and orthophosphorus (PO4-P) combined with chemical oxygen demand (COD) and O2 were conducted. Results showed that the required PO4-P/NOx-N ratio is approximately 0.006 mg/mg after phosphorous precipitation and flocculation. Profile measurements have proven to be an applicable and useful tool. It showed how nitrate and orthophosphorus are removed through the filter bed based on the PO4-P/NOx-N ratio. When orthophosphorus is removed more rapidly and efficiently compared to nitrate, the PO4-P/NOx-N ratio decreases. When PO4-P/NOx-N ratio thresholds are approximately 0.006 mg/mg for a certain period of time and water temperatures varied significantly, orthophosphorus limitation may occur. Changing the filter-bed configuration or decreasing the coagulant dosage can prevent limitation of the denitrifying process because of a phosphorous shortage. [ABSTRACT FROM AUTHOR]

The European Union presented in 2000 the European Water Framework Directive (WFD). Within the WFD approach the focus is more and more on ultra low nitrogen (,2.2mg N-total/L) and phosphorus concentrations (,0.15mg P-total/L) in waste water treatment plant (WWTP) effluent. Nitrogen concentrations of 2.2mg N-total/L can be reached with denitrifying filters as a tertiary treatment step. When combining nitrogen and chemical phosphorus removal in a filter, phosphorus limitation may occur. After nitrite accumulation, caused by phosphorus limitation, was measured in the filtrate water of the dual media filter, research was started to locate, to understand and to solve the problem. Profile measurements for nitrate, nitrite and orthophosphorus (PO4-P) combined with COD and O2 were conducted. Results show that the minimal required PO4-P/NOx-N ratio is 0.006 mg/mg after coagulation and flocculation. Profile measurements have proven to be a useful tool. It showed how nitrate and orthophosphorus are removed through the filter bed and it showed the consequences for the PO4-P/NOx-N ratio. When orthophosphorus is removed more rapidly compared to nitrate the PO4-P/NOx-N ratio decreases. When the PO4-P/NOx-N ratio becomes below 0.006mg/mg for a certain period of time, orthophosphorus limitation occurs. The solution can be either changing the filter bed configuration or decreasing the coagulant dosage [ABSTRACT FROM AUTHOR]

This study details the observed effects of atmospheric stability on characteristics of the surface layer in a low wind speed (U = 1.5 m s-1) regime of tropical West Africa. The aerodynamic roughness length, z0, and displacement height, d, obtained from profile wind-speed data at our bush land site (height ≈2 m) have values of 0.24 ± 0.10 m and 1.54 ± 0.04 m respectively. In the unstable range (-2.5 < Ri < -0.1; Ri is gradient Richardson number), the standard deviation in wind speed fluctuations, σu, increased from 0.57 ± 0.19 m s-1 to a maximum of 0.7 ± 0.2 m s-1 in near-neutral conditions, and in the stable range, the parameter decreased rapidly to 0.41 ± 0.15 m s-1 at Ri ≈ 0.2. In the same stability range, the horizontal wind dispersion, σθ, decreased with increasing stability from 19 ± 8 deg. to 13 ± 5 deg. The surface-layer integral quantity, σu/u*, when plotted as a function of stability, is in agreement with the empirical results. The ratio of sensible heat flux (estimated) to the net radiation ranged between 0.1 and 0.2 at nighttime, increasing to about 0.5 during the daytime, and showed a strong dependency on season. [ABSTRACT FROM AUTHOR]