Heat transfer during fluidized-bed coating

A fully implicit numerical method for linear parabolic free boundary problems with coupled and integral boundary conditions is described. The partial differential equation and the boundary conditions are time discretized with the method of lines. An auxiliary function is introduced to remove the coupled and integral boundary conditions from the resulting free boundary problem for ordinary differential equations. Once separated boundary conditions are obtained, invariant imbedding is used to solve the free boundary problem numerically. The method is illustrated by solving the heat transfer equations for the fluidized-bed coating of a thin-walled cylinder.     

High purity gadolinium by electrorefining in fused salts—II. Electrocrystallization in the LiFBaF2GdF3 mixture

The interaction of alkali metal and alkaline earth metal fluorides with gadolinium trifluoride is evaluated in terms of the Tobolsky parameter. BaF₂ is found to exert a pronounced destabilization effect on the tysonite structure of GdF₃. In comparison with the 75LiF25 mol% GdF₃ electrolyte, the 75LiF10BaF₂15 mol% GdF₃ mixture influenced the charge-transfer process in such a way as to reduce the deposition voltage by 0.1 V and to change the deposit morphology from uniaxial (001)-needles to block formations.The content of the interstitial elements H, N and O in the deposited gadolinium was 54, 25 and 79 ppm respectively. The highest concentrations of the other impurities were Li(22), Fe(16), Ba(35), La(3), Ce(3.3), Pr(2.7), Nd(8.9), Tb(20). Dy(2.4) and Th(4 ppm).     

Einfluß von Kobalt auf die martensitischen Umwandlungen in austenitischen Stählen mit rd. 18% Cr und 10% Ni

Röntgenographische, magnetische, metallographische und dilatometrische Untersuchung der martensitischen Umwandlung bei +20 und –196 °C an einer Legierungsreihe, bei der – ausgehend von einem kohlenstoffarmen Stahl mit rd. 18% Cr und 8% Ni– stufenweise je 7% Fe + 2% Cr + 1% Ni durch 10% Co ersetzt wurden, nach Abschrecken und zusätzlicher plastischerVerformung. Ermittlung des Einflusses von Kobalt auf mechanische und magnetische Eigenschaften, Dichte und Gitterkonstante des Austenits. Versuch der lückenlosen Überführung der hexagonalen ?-Phase austenitischer Chrom-Nickel-Stähle in die Tieftemperaturmodifikation des Kobalts durch zusätzliche Versuche an Legierungen, bei denen – ausgehend von rd. 40% Co, 10% Cr und 6% Ni – der Nickelgehalt bis auf 0% abgesenkt wurde.     

Mechanisms in fatigue strength improvement of thermomechanically manufactured automotive suspension springs

In a previous work, application of thermomechanical treatment (TMT) to suspension spring samples led to high increases in fatigue strength (up to 40 %). For the purpose of a better comprehension of these results, further investigations were carried out with major attention to the mechanical properties of quenched and tempered steel 50CrV4 and a Nb-microalloyed variant of this steel, respectively. First, the samples were ground prior to presetting, stress peening and subsequent dynamic testing. This was done to work out the influence of the surface state on the benefits of TMT. An extended program of materials testing was carried out with particular attention on the crack initiation and growth features of thermomechanically treated steel compared to conventional heat treatment (CHT). One of the results was that grinding of the spring surface causes further improvement of fatigue strength. On the other hand, the advantages of TMT compared to CHT are reduced as a result of surface grinding. The reason for this result is an overproportional increase in fatigue strength of CHT specimens due to grinding. An explanation imaginable for both the improvements caused by TMT and the reduction of these improvements after grinding could be the change in fracture mechanical properties. In particular TMT causes a significantly retarded crack initiation in the finite life range and an increased permissible stress intensity without crack formation.     

Diffusion of a hydrocarbon mixture in a one-dimensional zeolite channel: An exclusion model approach

Zeolite channels can be used as effective hydrocarbon traps. Earlier experiments [K.F. Czaplewski et al., Micropor. Mesopor. Mater. 56 (2002) 55] show that the presence of large aromatic molecules (toluene) block the diffusion of light hydrocarbon molecules (propane) inside the narrow pore of a zeolite sample. As a result, the desorption temperature of propane is significantly higher in the binary mixture than in the single-component case. In order to obtain further insight into these results, we use a simple lattice gas model of diffusion of hard-core particles to describe the diffusive transport of two species of molecules in a one-dimensional zeolite channel. Our dynamical Monte Carlo simulations show that taking into account an Arrhenius dependence of the single-molecule diffusion coefficient on temperature, one can explain many significant features of the temperature programmed desorption profile observed in experiments. However, on a closer comparison of the experimental curve and our simulation data, we find that it is not possible to reproduce the higher propane current than toluene current near the desorption peak seen in experiment. We argue that this is caused by a violation of strict single-file behavior.     

Using Parallel Packed Bed within a High Temperature Thermal Energy Storage System for CSP-Plants

In order to optimize the electricity yield of CSP （concentrated solar power） plants, TES （thermal energy storage） systems are regarded as an essential component. Furthermore, for many electricity grid operators, it is important to have spinning reserves in the grid and dispatchable power available, both offered by CSP-plants with integrated thermal energy storage. Enolcon is developing a new TES-system since several years. The system itself was designed to offer a principle simple and robust setup （with regard to execution and operation） and which is reducing the electricity costs of CSP-power plants by the consequent use of state of the art technology. Furthermore, such system shall be open to future developments of CSP-systems with regard to increasing steam temperatures and steam pressure. Such TES-system shall be commercially available for large scale application already in year 2014/2015. The key elements of the enolcon-TES are the open cycle using always ambient air with an air-air-heat exchanger and the arrangement of the storage material in such way to minimize the pressure losses and the own electricity consumption. The development is progressing in a structured way by studies, engineering works, TES-pilot plants, isothermal air flow test plant for the verification of the CFD-calculations, and since end of 2012 by the operation of a high temperature TES-module with all features of the large scale modules.     

Feasibility of monitoring large wind turbines using photogrammetry

Photogrammetry, which is a proven measurement technique based on determination of the 3D coordinates of the points on an object by using two or more images taken from different positions, is proposed to be a promising and cost efficient alternative for monitoring the dynamic behavior of wind turbines. The pros and cons of utilizing this measurement technique for several applications such as dynamic testing or health monitoring of large wind turbines are discussed by presenting the results of the infield tests performed on a 2.5 MW - 80 m diameter - wind turbine.     

Mycotoxin exposure and human cancer risk: A systematic review of epidemiological studies

In recent years, there has been an increasing interest in investigating the carcinogenicity of mycotoxins in humans. This systematic review aims to provide an overview of data linking exposure to different mycotoxins with human cancer risk. Publications (2019 and earlier) of case–control or longitudinal cohort studies were identified in PubMed and EMBASE. These articles were then screened by independent reviewers and their quality was assessed according to the Newcastle–Ottawa scale. Animal, cross‐sectional, and molecular studies satisfied criteria for exclusion. In total, 14 articles were included: 13 case–control studies and 1 longitudinal cohort study. Included articles focused on associations of mycotoxin exposure with primary liver, breast, and cervical cancer. Overall, a positive association between the consumption of aflatoxin‐contaminated foods and primary liver cancer risk was verified. Two case–control studies in Africa investigated the relationship between zearalenone and its metabolites and breast cancer risk, though conflicting results were reported. Two case–control studies investigated the association between hepatocellular carcinoma and fumonisin B1 exposure, but no significant associations were observed. This systematic review incorporates several clear observations of dose‐dependent associations between aflatoxins and liver cancer risk, in keeping with IARC Monograph conclusions. Only few human epidemiological studies investigated the associations between mycotoxin exposures and cancer risk. To close this gap, more in‐depth research is needed to unravel evidence for other common mycotoxins, such as deoxynivalenol and ochratoxin A. The link between mycotoxin exposures and cancer risk has mainly been established in experimental studies, and needs to be confirmed in human epidemiological studies to support the evidence‐based public health strategies.     

A note on large-scale logistic prediction: using an approximate graphical model to deal with collinearity and missing data

Large-scale prediction problems are often plagued by correlated predictor variables and missing observations. We consider prediction settings in which logistic regression models are used and propose a novel approach to make accurate predictions even when predictor variables are highly correlated and only partly observed. Our approach comprises three steps: first, to overcome the collinearity issue, we propose to model the joint distribution of the outcome variable and the predictor variables using the Ising network model. Second, to render the application of Ising networks feasible, we use a latent variable representation to apply a low-rank approximation to the network’s connectivity matrix. Finally, we propose an approximation to the latent variable distribution that is used in the representation to handle missing observations. We demonstrate our approach with numerical illustrations.