Non-linear MPC for winding loss optimised torque control of anisotropic PMSM

For a non-linear anisotropic permanent magnet synchronous machine (PMSM), a prediction model for model predictive control (MPC) considering effects like cross-coupling and saturation is developed in a straight forward procedure. The objective of the designed MPC is either tracking of reference currents or torque tracking. Both approaches use the projected fast gradient method (PFGM) as optimisation algorithm. The latter approach makes look-up-tables for current references obsolete and additionally minimises winding losses. This two approaches are compared in a simulation study with a state of the art PI controller

The polarization properties of a tilted polarizer

Polarizers are key components in optical science and technology. Thus, understanding the action of a polarizer beyond oversimplifying approximations is crucial. In this work, we study the interaction of a polarizing interface with an obliquely incident wave experimentally. To this end, a set of Mueller matrices is acquired employing a novel procedure robust against experimental imperfections. We connect our observation to a geometric model, useful to predict the effect of polarizers on complex light fields.Comment: 11 pages, 5 figure

Determination of active sites during gasification of biomass char with CO2 using temperature-programmed desorption. Part 2: Influence of ash components

The present work is the second part of a study conducted with the aim to determine the amount of active sites present on the surface of a biomass char participating in the gasification reaction with CO2 using the temperature programmed desorption (TPD) technique. In part 1, the methodology and experimental results during TPD of partially gasified samples of beech wood char (WC1600) using CO2 as gasification agent are presented. This work focusses on the influence of the main inorganic ash components of WC1600 on the CO2 and CO signals obtained during TPD of partially gasified char samples. Furthermore, an activated carbon with ash content lower than 1 wt-% is impregnated with Ca and K and partially gasified followed by a TPD analysis. CO2 and CO signals obtained during TPD result from decomposition of oxygenated surface complexes and decomposition reactions of ash components. During gasification, three different kinds of sites are present on the surface of the char: stable, reactive and catalytically active sites. The latter are a measure of the catalytic influence of inorganic matter during char gasification. From the analysis of the TPD spectra, it can be concluded that gasification of WC1600 is dominated by the catalytic influence exerted by Ca and K. Formation of oxygenated surface complexes on WC1600 is limited, possibly due to the high temperature at which the sample was pyrolyzed (1600 °C). However, a direct correlation between specific conversion rate and the amount of reactive and catalytically active sites is developed from the experimental results, corrected by the contribution of ash decomposition

Influence of pressure on the gasification kinetics of two high-temperature beech wood chars with CO2_{2}, H2_{2}O and its mixture

This paper presents experimental data and modeling approaches to describe the influence of CO$_{2}$ and H$_{2}$O partial pressure as well as absolute pressure on the gasification kinetics of two different beech wood chars. The chars were produced at 1400 °C (P1400) and 1600 °C (P1600) at high-heating rates and short residence times in a drop-tube reactor. The gasification experiments were conducted in a single-particle reactor with forced flow-through conditions reducing diffusional effects to a minimum. The interpretation of the experimentally determined reaction rates during gasification with CO$_{2}$, H$_{2}$O and its mixture is based on the char properties (graphitization, ash dispersion and morphology) presented in a previous publication. During gasification with CO$_{2}$, P1600 shows higher reactivity as compared to P1400 for all CO$_{2}$ partial pressures and temperatures applied. The higher reactivity of P1600 during CO$_{2}$ gasification may be explained by a CaO film on the char surface catalyzing the char-CO$_{2}$ gasification reaction. On the other hand, P1400 shows higher reactivity towards H$_{2}$O which may be evoked by the lower graphitization degree and higher specific surface area. Reaction kinetic modeling for single atmosphere gasification was successfully carried out using a power law approach. The Langmuir-Hinshelwood model, however, only gave good results where a possible saturation of the char surface at high pressure was observed. Increasing the CO$_{2}$ partial pressure during gasification in mixed CO$_{2}$/H$_{2}$O atmospheres leads to higher reactivity for both chars. The reaction rate r$_{mix}$ can be expressed by addition of the single atmosphere reaction rates in the low pressure area suggesting a separate active site mechanism. Catalytic activity of CaO increases the P1600 reactivity distinctively for lower H$_{2}$O and CO$_{2}$ partial pressures. For higher H$_{2}$O and CO$_{2}$ partial pressures, P1600 reactivity stagnates due to lower specific surface area and higher graphitization degree. Here, a common active sites mechanism can be assumed

Adoptive Immunotherapy in Chimeras with Donor Lymphocytes

Allogeneic stem cell transplantation has a well-defined indication in the treatment of hematological malignancies. The beneficial immune effect of allogeneic marrow transplantation has long been known, but only recently have methods been developed to separate the graft-versus-leukemia (GVL) effect from graft-versus-host disease (GVHD). Animal experiments have shown that lymphocytes from the marrow donor can be transfused without causing severe GVHD if stable chimerism and tolerance is established. First clinical studies have been preformed in patients with recurrent chronic myelogenous leukemia. In these patients complete molecular remissions were induced that persist without further maintenance treatment. These results have been confirmed in larger multicenter studies in Europe and the USA. The best results were obtained in chronic myelogenous leukemia (CML); repeated successes have been reported in relapsing acute myeloid leukemia (AML), myelodysplastic syndromes and multiple myeloma (MMY), and rare responses were reported for acute lymphoid leukemia. Contrary to animal experiments GVHD has been observed in human patients although to a lesser extent than expected in transplants not given immunosuppression. Secondly myelosuppression has been observed in patients treated with relapsing CML. In CML the incidence of GVHD could be reduced by depleting CD8(+) T cells from the donor lymphocyte concentrate. Alternatively only small numbers of T lymphocytes can be transfused and in the case of failing responses, the numbers of donor lymphocytes may be increased. Results in recurrent AML have been improved by the use of low-dose cytosine arabinoside, granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor mobilized blood cells as compared to lymphocytes only. In MMY the response rate is higher than in AML, but the remissions are of limited duration in most patients. Several protocols have been designed to include preemptive donor lymphocyte transfusion in patients with a high relapse risk after transplantation. Problems remain to avoid chronic GVHD and to circumvent the immune escape mechanisms of leukemia. Copyright (C) 2003 S. Karger AG, Basel

Is sunlight good for our heart?

Humans evolved being exposed for about half of the day to the light of the sun. Nowadays, exposure to sunlight is actively discouraged for fear of skin cancer, and contemporary lifestyles are associated with long hours spent under artificial light indoors. Besides an increasing appreciation for the adverse effects of these life-style-related behavioural changes on our chronobiology, the balance between the beneficial and harmful effects of sunlight on human health is the subject of considerable debate, in both the scientific and popular press, and the latter is of major public health significance. While there is incontrovertible evidence that ultraviolet radiation (UVR) in the form of sunlight is a significant predisposing factor for non-melanoma and melanoma skin cancers in pale skinned people,1 a growing body of data suggest general health benefits brought about by sunlight.2 These are believed to be mediated either by melatonin or vitamin D. Melatonin is produced from serotonin by the pineal gland located in the centre of the brain during periods of darkness, and its release is suppressed as a function of the visible light intensity sensed through ocular photoreceptors. Vitamin D is formed by ultraviolet B (UVB)-mediated photolysis of 7-dehydrocholesterol in the skin. Both melatonin and vitamin D are pleiotropic hormones that exert a multitude of cellular effects by interacting with membrane and nuclear receptors, and receptor-independent actions. People with more heavily pigmented skin require higher doses of UVB to produce adequate amounts of vitamin D, and this may have been an evolutionary driver to the variation of human skin colour with latitude and intensity of solar irradiation. Our degree of exposure to sunlight is easily modified by behavioural factors such as the use of clothing, sunglasses, and sun-blocking creams, and time spent outdoors. Balancing the carcinogenic risks with the requirement for vitamin D has led to advice on moderating sun exposure, while supplementing food with vitamin D. Guidance on such behaviour is part of the public health campaigns in most countries with Caucasian populations. Following these suggestions, we may, however, be missing out on other health benefits provided by natural sunlight that are less obvious and unrelated to the above classical mediators