Self-tuning control of an ore crusher

An industrial application is described where a self-tuning regulator is used for control of an ore crusher. There are difficult control problems associated with this process due to significant variations in operating conditions and long time delays in the system. The design of a self-tuning regulator for the crusher is discussed in detail. During this case study a temporary digital control loop was set up. A process computer at the University of Lund was connected to the ore crushing plant at 1800 km distance. When a self-tuning regulator is applied to a process with constant but unknown parameters, it will under certain conditions converge to a minimum variance strategy. The parameters of the ore crusher can hardly be considered as constant. However, it has been demonstrated practically that the use of exponential forgetting in the parameter estimation performed in the algorithm will give a very good regulator for the crusher.     

An alternative definition of the reference temperature to estimate the creep deformation of a thermally loaded tube

The reference concept is applied to the creep deformation of an axially loaded tube subjected to a two-dimensional temperature distribution. First the analytical method given in the literature for the determination of the reference stress is extended, resulting directly in expressions for both the reference stress and the reference temperature. Since these expressions can be solved only with a considerable amount of computation, an alternative definition of the reference values is suggested, which is rather simple in application. A further advantage of the new method is that the creep rate resulting from a uniaxial, isothermal creep test at its reference values can be transfered directly to the structure. The prediction of creep rate is in a good agreement with the steady state solution which is shown for various types of temperature fields. The absolute magnitude of error may be somewhat larger for the new method compared to the old one. But even if an unfavourable combination of material constants is used, this disadvantage is not serious since the errors do not surpass the scatter of experimental data usually obtained in creep tests. Regarding the tendency to overestimate or underestimate the creep rate, it cannot be decided in general whether the new or the old definition provides the better prediction, since the error is a complex function of the temperature field applied.     

Mathematische Formulierung der Erzreduktion für ein Hochofenmodell

Ableitung eines reaktionskinetischen Ansatzes zur Beschreibung der Erzreduktion im Hochofen nach einer Reaktion erster Ordnung. Erörterung der möglichen Abweichungen von einer Reaktion erster Ordnung. Übertragung der in Laboratoriumsversuchen an niedrigen Schüttungen ermittelten Reaktionsdaten auf Hochofenverhältnisse. Aussagen über die Verweilzeitverteilung der Gasmoleküle innerhalb der Schüttung. Beschreibung des Vorgehens bei der Bestimmung der bezogenen Reduktionsgeschwindigkeiten und der effektiven Gleichgewichtszusammensetzung des Reaktionsgases. Angaben zur Erfassung des Einflusses von Wasserstoffgehalten auf die Reduktionsgeschwindigkeit. Aussagen über den Ablauf der Wassergasreaktion im Hochofen.     

Joint optimization of an autoencoder for clustering and embedding

Machine Learning - Deep embedded clustering has become a dominating approach to unsupervised categorization of objects with deep neural networks. The optimization of the most popular methods...     

Prostaglandin E synthase 2 (PTGES2) Arg298His polymorphism and parameters of the metabolic syndrome

The prostaglandin E synthase 2 (PTGES2) gene maps to a locus linked to obesity and is involved in the synthesis of the antilipolytic compound prostaglandin E(2). In a recent study, we found an association of the minor PTGES2 Arg298His allele and lower risk of type 2 diabetes mellitus in the European Investigation into Cancer and Nutrition (EPIC) and Cooperative Health Research in the Augsburg Region (KORA) cohorts. Here, we employed our Metabolic Intervention Cohort Kiel (MICK) to assess the influence of the PTGES2 Arg298His polymorphism on a wider scale of parameters of the metabolic syndrome and postprandial metabolism. In comparison to subjects homozygous for the Arg allele, carriers of the His-allele showed significantly lower fasting insulin (geometric mean +/- SEM: 11.8 muU/mL, 11.41-12.25 versus 13.0, 12.71-13.33; p = 0.023), lower postprandial insulin levels after an oral glucose tolerance test (area under the curve 77.2, 74.07-80.52 versus 81.2, 78.8-83.63; p = 0.023) and lower homeostasis model assessment (HOMA)-insulin-resistance (3.030, 2.909-3.157 versus 3.346, 3.257-3.438; p = 0.041) and HOMA-beta-cell-function (107.2, 104.04-110.52 versus 117.2, 114.65-119.71; p = 0.019). Adjustment for body mass index (BMI) resulted in a loss of these significant differences. BMI tended to show lower values in His-allele carriers, (p = 0.067). In conclusion, risk-reducing effects of the minor His allele of the PTGES2 Arg298His polymorphism could be mediated partly by lowered BMI.     

Synthesis of active carbon-based catalysts by chemical vapor infiltration for nitrogen oxide conversion

Direct reduction of nitrogen oxides is still a challenge. Strong efforts have been made in developing noble and transition metal catalysts on microporous support materials such as active carbons or zeolites. However, the required activation energy and low conversion rates still limit its breakthrough. Furthermore, infiltration of such microporous matrix materials is commonly performed by wet chemistry routes. Deep infiltration and homogeneous precursor distribution are often challenging due to precursor viscosity or electrostatic shielding and may be inhibited by pore clogging. Gas phase infiltration, as an alternative, can resolve viscosity issues and may contribute to homogeneous infiltration of precursors. In the present work new catalysts based on active carbon substrates were synthesized via chemical vapor infiltration. Iron oxide nano clusters were deposited in the microporous matrix material. Detailed investigation of produced catalysts included nitrogen oxide adsorption, X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Catalytic activity was studied in a recycle flow reactor by time-resolved mass spectrometry at a temperature of 423 K. The infiltrated active carbons showed very homogeneous deposition of iron oxide nano clusters in the range of below 12 to 19 nm, depending on the amount of infiltrated precursor. The specific surface area was not excessively reduced, nor was the pore size distribution changed compared to the original substrate. Catalytic nitrogen oxides conversion was detected at temperatures as low as 423 K.     

Broadband Omnidirectional Diversion of Light in Hybrid Plasmonic‐Photonic Heterocrystals

Broadband, omnidirectional, and polarization‐independent diversion has been achieved of more than 90% of the light flow intensity off its incidence direction using hybrid metal–dielectric plasmonic‐photonic heterocrystals. These architectures were prepared by depositing metal film on the interface between two photonic crystals of different parameters. The magnitude of light losses was extracted from angle‐resolved measurements of transmission and reflectance spectra. Comparing these data for different stages of constructing the complex architecture, the diffraction in colloidal crystals, the excitation and radiative decay of short‐living surface plasmon polaritons in a corrugated metal film and the eigenmode mismatch at the interface between two different photonic crystals were identified as corroborating physical mechanisms behind the light diversion.     

Effects of perimortem stress on farmed Atlantic cod product quality: a baseline study

The potential effects of handling stress on the product quality of farmed Atlantic cod were studied in a controlled experiment (fish anesthetized with metomidate or isoeugenol, or subjected to stress by chasing for 30 min). For comparison, stress and fillet quality was also studied for commercially slaughtered farmed cod (fish sampled from waiting cage, after pumping and stunning with carbon dioxide, and after bleeding and chilling). Baseline values for stress-related parameters (blood chemistry, muscle high-energy phosphates and inosine monophospate, initial pH, muscle twitches, and rigor mortis) of rested Atlantic cod have been established. Since our stress bout showed that this species was not easily excitable, we were less convinced that we actually did study the other extreme, namely, exhausted fish. Nevertheless, the present data from the commercial slaughter of cod suggested that our stress bout was of adequate magnitude to represent potential poor handling routines. Our results consistently showed largely no differences between treatments, and that perimortem handling stress did not cause inferior flesh quality. This suggested that farmed cod can be processed with little risk of reducing product quality (quality index, fillet water content, water-holding capacity, ultimate pH, adenosine triphosphate-related degradation products and K-value, skin and fillet color, water and salt-soluble proteins, hardness, and gaping). For better maintenance of skin appearance after storage, the importance of storing the gutted cod on the belly, avoiding direct contact between skin and crushed ice, is demonstrated.