Multilevel surrogate modeling of an amine scrubbing process for CO2capture

Surrogate models provide a powerful method for simplifying calculations within complex simulations. While surrogate models are broadly applied within chemical engineering, little research exists investigating the level of surrogacy's impact on a simplified process model. In this work, artificial neural networks (ANN) and Kriging models are used as surrogate models at the process, process unit, and thermodynamic levels for a CO₂ amine scrubbing process. The surrogated models are evaluated against an Aspen Plus simulation for accuracy, convergence behavior, computational cost, and ability to extrapolate. The thermodynamic and process unit models can better handle discontinuous, non-smooth behavior, and convergence issues in the surrogated truth model, but poor conditioning in the final system of equations results in a lower accuracy and convergence rate than the process level surrogate. Beyond model accuracy, availability of diverse data, intended re-usability, and the desired outputs must be considered when selecting a level of abstraction.     

Filtration effectiveness of HVAC systems at near‐roadway schools

Concern for the exposure of children attending schools located near busy roadways to toxic, traffic‐related air pollutants has raised questions regarding the environmental benefits of advanced heating, ventilation, and air‐conditioning (HVAC) filtration systems for near‐road pollution. Levels of black carbon and gaseous pollutants were measured at three indoor classroom sites and at seven outdoor monitoring sites at Las Vegas schools. Initial HVAC filtration systems effected a 31–66% reduction in black carbon particle concentrations inside three schools compared with ambient air concentrations. After improved filtration systems were installed, black carbon particle concentrations were reduced by 74–97% inside three classrooms relative to ambient air concentrations. Average black carbon particle concentrations inside the schools with improved filtration systems were lower than typical ambient Las Vegas concentrations by 49–96%. Gaseous pollutants were higher indoors than outdoors. The higher indoor concentrations most likely originated at least partially from indoor sources, which were not targeted as part of this intervention.     

Generation of classification trees from variable weighted features

Trees are a useful framework for classifying entities whose attributes are, at least partially, related through a common ancestry, such as species of organisms, family members or languages. In some common applications, such as phylogenetic trees based on DNA sequences, relatedness can be inferred from the statistical analysis of unweighted attributes. The vast majority of mutations that survive across generations are evolutionarily neutral, which means that most genetic differences between species will have accumulated independently and randomly. In these cases, it is possible to calculate the tree from a precomputed matrix of distances. In other cases, such as with anatomical traits or languages, the assumption of random and independent differences does not hold, making it necessary to consider some traits to be more relevant than others for determining how related two entities are. In this paper, we present a constraint programming approach that can enforce consistency between bounds on the relative weight of each trait and tree topologies, so that the user can best determine which sets of traits to use and how the entities are likely to be related.     

Wet-etching of precipitation-based thin film microstructures for micro-solid oxide fuel cells

In micro-solid oxide fuel cells (μ-SOFCs) ceramic thin films are integrated as free-standing membranes on micromachinable substrates such as silicon or Foturan^® glass ceramic wafers. The processing of μ-SOFCs involves unavoidable dry- or wet-chemical etching for opening the substrate below the free-standing fuel cell membranes. In the first part of this paper current dry- and wet-chemical etchants for structuring of ceria-based electrolyte materials are reviewed, and compared to the etch-rates of common μ-SOFCs substrates. Wet-chemical etchants such as hydrofluoric acid are of high interest in μ-SOFC processing since they allow for homogeneous etching of ceria-based electrolyte thin films contrary to common dry-etching methods. In addition, HF acid is the only choice for substrate etching of μ-SOFC based on Foturan^® glass ceramic wafers. Etching of Ce_0.8Gd_0.2O_1.9?x spray pyrolysis electrolyte thin films with 10% HF:H₂O is investigated. The etch-resistance and microstructures of these films show a strong dependency on post deposition annealing, i.e. degree of crystallinity, and damage for low acid exposure times. Their ability to act as a potential etch-resistance for μ-SOFC membranes is broadly discussed. Guidance for thermal annealing and etching of Ce_0.8Gd_0.2O_1.9?x thin films for the fabrication of Foturan^®-based μ-SOFCs is given.     

Rotary actuators with multipole ring magnets

Rotary actuators are electromagnetic devices developing mechanical torque with limited rotary motion. Because of their simplicity and low cost they are finding more and more applications, especially in the automotive field. This paper describes a novel homopolar rotary actuator with a ring-type radially magnetized multipolar permanent magnet featuring a high force density “transverse flux” configuration which performs a spring action by developing electromagnetic torques with limited angular movement. Because of the magnetically complicated and nonsymmetrical rotary actuator configuration, the analysis of this actuator is based on 3-D finite element software. The analysis, which is well supported by test results, shows that symmetrical magnetic forces in both directions of rotation were achieved with a stable equilibrium position, satisfying all design requirements to enhance the basic hydraulic power steering system of passenger vehicles     

Zutrittskontrolle mit Gesichtserkennung

Firmen&ProdukteDehn Austria

überspannungs-schutz in der Telekommunikation     

In-situ deformation of an open-cell flexible polyurethane foam characterised by 3D computed microtomography

The deformation behaviour of an open-cell flexible polyurethane foam was observed using X-ray microtomography on the ID19 beamline at the ESRF in Grenoble, France. Tomographs, consisting of 1024 voxels cubed, were collected with a voxel size of 6.6 m from a small region near the centre of the foam at a range of compressive strains between 0 and 80%. The results show that the initial stages of compression are taken up by small amounts of elastic bending in struts that are inclined to the compression direction. At 23% strain, entirely collapsed bands were observed in the structure. By 63% strain, there was evidence of struts impinging on each other, corresponding to the densification regime. The compression of an irregular foam (i.e. one with strut length and cell size distributions) appears to involve a sudden change in modulus, accompanied by localised increases in density. Observations of this nature would have been extremely difficult to interpret unambiguously without the ability to carry out sequential microtomographic imaging under realistic in situ loading conditions. The process of finite element analysis (FEA) was begun by constructing node-strut models from the experimental data by a mathematical skeletonisation process. These were used to derive node coordination, strut-length and cell-size distributions. However, direct comparison of the elastic properties with FEA was hampered by the absence of periodicity in the experimentally determined foam structures.     

PSICO: Solving Protein Structures with Constraint Programming and Optimization

In this paper we propose PSICO (Processing Structural Information with Constraint programming and Optimisation) as a constraint-based approach to determining protein structures compatible with distance constraints obtained from Nuclear Magnetic Resonance (NMR) data. We compare the performance of our proposed algorithm with DYANA (Dynamics algorithm for NMR applications) an existing commercial application based on simulated annealing. On a test case with experimental data on the dimeric protein Desulforedoxin, the method proposed here supplied similar results in less than 10 minutes compared to approximately 10 hours of computation time for DYANA. Although the quality of results can still be improved, this shows that CP technology can greatly reduce computation time, a major advantage because structural NMR technique generally demands multiple runs of structural computation.