Zur numerischen Berechnung von Wirbelstromverlusten in Konstruktionselementen von Induktionsöfen

Abstract Author: Wolfgang Weigel Title: About the numerical calculation of eddy current losses in constructional components of induction furnaces _______________________________________________________________________________________ The aim of the presented dissertation is the computation of eddy currents and eddy current losses in the whole inductor of channel induction furnaces. The reduction of eddy current losses in constructional components, such as inductor casing and cooling cylinder, and the improvement of the electric efficiency of channel induction furnaces can be achieved by performing specific steps during the design process. Therefore a lot of interacting parameters influencing the electromagnetic field distribution and influencing the height of the eddy current losses have to be taken into account. A convenient way to do this is by means of numerical simulation. Because of the complex geometry of the channel furnace it is obvious that the calculation has to be performed in three-dimensional space. Maxwell's partial differential equations act as a basic model for describing the electromagnetic field in induction heating applications. We assume that the field quantities are varying sinusoidal with time and the material properties are constant with time. The differential equations describing the electromagnetic field are integrated as an A-Phi-formu- lation by means of the finite element method (FEM) using the Galerkin procedure. The local approximation for one single finite element is extended to the global approximation over all finite elements in the whole solution area. The matrix generation of the algebraic system of equations is shown in detail. The necessary boundary and symmetry conditions are taken into account. Preliminary investigations at one simplified model of the channel furnace have been done in order to find out how to reduce the numerical problem size during numerical solution without decreasing the solution accuracy. All experiences of the simple model were useful for the calculation of the twin-coil channel induction furnace used in copper melting applications. The usability of the presented finite element model for the channel induction furnace was tested by a comparison of computed and measured results of eddy current losses at an existing furnace. A simple cooling cylinder model consisting of a slotted tube with inner inductor was built to compare calculated and measured values. With this model the suitability of the choosen A-Phi- formulation for calculating induction heating problems was shown once again. Another essential part of the presented paper shows a method to reduce the solution area into a smaller area than the original one. Thus it is possible to solve extensive problems reaching the required solution accuracy with a higher number of finite elements in the detail solution area, although the restricted computer main memory capacity has not changed.Spezieller Inhalt der vorliegenden Dissertationsschrift ist die Wirbelstrom- und Verlustberech- nung in Induktoreinheiten von Induktionsrinnenöfen. Für die Verringerung der Wirbelstromverluste in den Bauteilen und die Erhöhung des elektrischen Wirkungsgrades von Induktions-Rinnenöfen sind eine Reihe von konstruktiven Maßnahmen erforderlich. Dabei sind eine Vielzahl unterschiedlicher Parameter und Einflußgrößen auf den Feldverlauf sowie die Verluste im jeweiligen Konstruktionselement des Ofens und die Auswirkungen auf andere Ofenbauteile zu berücksichtigen. Aufgrund der komplizierten Ofengeometrie ist nur eine dreidimensionale numerische Rechnung sinnvoll. Die theoretische Grundlage für die Feld- und Wirbelstromberechnung liefert das System der Maxwell-Gleichungen, das auf die quasistationären Vorgänge der Induktionserwärmung angewendet wird. Als Voraussetzungen werden sinusförmige Erregung und zeitlich konstante Materialwerte berücksichtigt. Für die Beschreibung des elektromagnetischen Feldes wird die A-Phi-Formulierung angewendet. Das System der feldbeschreibenden Differentialgleichungen wird unter Berücksichtigung der Rand- und Symmetriebedingungen mit der Finite Elemente Methode (FEM) gelöst. Die Herleitung des FEM-Lösungsansatzes erfolgt nach dem Verfahren von Galerkin unter Erweiterung des lokalen Näherungsansatz im Einzelelement zum globalen Lösungsansatz für das Gesamtlösungsgebiet. Der Aufbau des numerisch mit dem Computer lösbaren algebraischen Gleichungssystems wird unter Berücksichtigung der Rand- und Symmetriebedingungen ausführlich dargestellt. Notwendige Voruntersuchungen für die Berechnung der Induktoreinheit eines doppelloopigen Rinnenofens zum Schmelzen von Kupfer beinhalten das Ziel zur Reduzierung des numerischen Aufwandes unter Einhaltung einer ausreichenden Rechengenauigkeit. Der Vergleich von Ergebnissen aus der numerischeren Wirbelstromverlustberechnung des doppelloopigen Ofens mit Meßergebnissen vom ausgeführten Ofen bestätigt die Anwendbarkeit des Finite Elemente Modells für den Rinnenofen. Die Eignung des A-Phi- Lösungsansatzes für die Induktionserwärmung wird durch den Vergleich von Rechen- und Meßwerten an einem Kühlzylindermodell, d.h. einer Anordnung aus Induktor und geschlitztem Rohr, zusätzlich bekräftigt. Ein weiterer wesentlicher Bestandteil dieser Arbeit ist die Methode zur Reduzierung des Lösungsgebietes auf einen Teilausschnitt, damit auch umfangreiche Problemstellungen bei begrenzter Speicherkapazität der Rechenanlage noch mit der erforderlichen Genauigkeit beherrscht werden können

Direct observation of the potential distribution within organic light emitting diodes under operation

We show the first direct measurement of the potential distribution within organic light emitting diodes (OLEDs) under operation and hereby confirm existing hypotheses about charge transport and accumulation in the layer stack. Using a focused ion beam to mill holes in the diodes we gain access to the cross section of the devices and explore the spatially resolved potential distribution in situ by scanning Kelvin probe microscopy under different bias conditions. In bilayer OLEDs consisting of tris(hydroxyquinolinato) aluminum (Alq_3)/N, N ′-bis(naphthalene-1-yl)-N,N ′-bis(phenyl) benzidine (NPB) the potential exclusively drops across the Alq_3 layer for applied bias between onset voltage and a given transition voltage. These findings are consistent with previously performed capacitance–voltage measurements. The behavior can be attributed to charge accumulation at the interface between the different organic materials. Furthermore, we show the potential distribution of devices with different cathode structures and degraded devices to identify the cathode interface as main culprit for decreased performance

An exceptional Albanian family with seven children presenting with dysmorphic features and mental retardation: maternal phenylketonuria

BACKGROUND: Phenylketonuria is an inborn error of amino acid metabolism which can cause severe damage to the patient or, in the case of maternal phenylketonuria, to the foetus. The maternal phenylketonuria syndrome is caused by high blood phenylalanine concentrations during pregnancy and presents with serious foetal anomalies, especially congenital heart disease, microcephaly and mental retardation. CASE PRESENTATION: We report on an affected Albanian woman and her seven children. The mother is affected by phenylketonuria and is a compound heterozygote for two pathogenetic mutations, L48S and P281L. The diagnosis was only made in the context of her children, all of whom have at least one severe organic malformation. The first child, 17 years old, has a double-chambered right ventricle, vertebral malformations and epilepsy. She is also mentally retarded, microcephalic, exhibits facial dysmorphies and small stature. The second child, a girl 15 years of age, has severe mental retardation with microcephaly, small stature and various dysmorphic features. The next sibling, a boy, died of tetralogy of Fallot at the age of three months. He also had multiple vertebral and rib malformations. The subsequent girl, now eleven years old, has mental retardation, microcephaly and epilepsy along with facial dysmorphy, partial deafness and short stature. The eight-year-old child is slightly mentally retarded and microcephalic. A five-year-old boy was a premature, dystrophic baby and exhibits mental retardation, dysmorphic facial features, brachydactyly and clinodactyly of the fifth finger on both hands. Following a miscarriage, our index case, the youngest child at two years of age, is microcephalic and mentally retarded and shows minor facial anomalies. All children exhibit features of phenylalanine embryopathy caused by maternal phenylketonuria because the mother had not been diagnosed earlier and, therefore, never received any diet. CONCLUSION: This is the largest family suffering from maternal phenylketonuria reported in the literature. Maternal phenylketonuria remains a challenge, especially in woman from countries without a neonatal screening program. Therefore, it is mandatory to be alert for the possibility of maternal phenylketonuria syndrome in case of a child with the clinical features described here to prevent foetal damage in subsequent siblings

Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions

Significant reductions in stratospheric ozone occur inside the polar vortices each spring when chlorine radicals produced by heterogeneous reactions on cold particle surfaces in winter destroy ozone mainly in two catalytic cycles, the ClO dimer cycle and the ClO/BrO cycle. Chlorofluorocarbons (CFCs), which are responsible for most of the chlorine currently present in the stratosphere, have been banned by the Montreal Protocol and its amendments, and the ozone layer is predicted to recover to 1980 levels within the next few decades. During the same period, however, climate change is expected to alter the temperature, circulation patterns and chemical composition in the stratosphere, and possible geo-engineering ventures to mitigate climate change may lead to additional changes. To realistically predict the response of the ozone layer to such influences requires the correct representation of all relevant processes. The European project RECONCILE has comprehensively addressed remaining questions in the context of polar ozone depletion, with the objective to quantify the rates of some of the most relevant, yet still uncertain physical and chemical processes. To this end RECONCILE used a broad approach of laboratory experiments, two field missions in the Arctic winter 2009/10 employing the high altitude research aircraft M55-Geophysica and an extensive match ozone sonde campaign, as well as microphysical and chemical transport modelling and data assimilation. Some of the main outcomes of RECONCILE are as follows: (1) vortex meteorology: the 2009/10 Arctic winter was unusually cold at stratospheric levels during the six-week period from mid-December 2009 until the end of January 2010, with reduced transport and mixing across the polar vortex edge; polar vortex stability and how it is influenced by dynamic processes in the troposphere has led to unprecedented, synoptic-scale stratospheric regions with temperatures below the frost point; in these regions stratospheric ice clouds have been observed, extending over >106km2 during more than 3 weeks. (2) Particle microphysics: heterogeneous nucleation of nitric acid trihydrate (NAT) particles in the absence of ice has been unambiguously demonstrated; conversely, the synoptic scale ice clouds also appear to nucleate heterogeneously; a variety of possible heterogeneous nuclei has been characterised by chemical analysis of the non-volatile fraction of the background aerosol; substantial formation of solid particles and denitrification via their sedimentation has been observed and model parameterizations have been improved. (3) Chemistry: strong evidence has been found for significant chlorine activation not only on polar stratospheric clouds (PSCs) but also on cold binary aerosol; laboratory experiments and field data on the ClOOCl photolysis rate and other kinetic parameters have been shown to be consistent with an adequate degree of certainty; no evidence has been found that would support the existence of yet unknown chemical mechanisms making a significant contribution to polar ozone loss. (4) Global modelling: results from process studies have been implemented in a prognostic chemistry climate model (CCM); simulations with improved parameterisations of processes relevant for polar ozone depletion are evaluated against satellite data and other long term records using data assimilation and detrended fluctuation analysis. Finally, measurements and process studies within RECONCILE were also applied to the winter 2010/11, when special meteorological conditions led to the highest chemical ozone loss ever observed in the Arctic. In addition to quantifying the 2010/11 ozone loss and to understand its causes including possible connections to climate change, its impacts were addressed, such as changes in surface ultraviolet (UV) radiation in the densely populated northern mid-latitudes

Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions : (RECONCILE) ; activities and results

The international research project RECONCILE has addressed central questions regarding polar ozone depletion, with the objective to quantify some of the most relevant yet still uncertain physical and chemical processes and thereby improve prognostic modelling capabilities to realistically predict the response of the ozone layer to climate change. This overview paper outlines the scope and the general approach of RECONCILE, and it provides a summary of observations and modelling in 2010 and 2011 that have generated an in many respects unprecedented dataset to study processes in the Arctic winter stratosphere. Principally, it summarises important outcomes of RECONCILE including (i) better constraints and enhanced consistency on the set of parameters governing catalytic ozone destruction cycles, (ii) a better understanding of the role of cold binary aerosols in heterogeneous chlorine activation, (iii) an improved scheme of polar stratospheric cloud (PSC) processes that includes heterogeneous nucleation of nitric acid trihydrate (NAT) and ice on non-volatile background aerosol leading to better model parameterisations with respect to denitrification, and (iv) long transient simulations with a chemistry-climate model (CCM) updated based on the results of RECONCILE that better reproduce past ozone trends in Antarctica and are deemed to produce more reliable predictions of future ozone trends. The process studies and the global simulations conducted in RECONCILE show that in the Arctic, ozone depletion uncertainties in the chemical and microphysical processes are now clearly smaller than the sensitivity to dynamic variability

Globaliseerumise seosed sissetulekute ebavõrdsusega arenguriikide ning üleminekujärgus majandusega riikide näitel

Üha süvenev sissetulekute ebavõrdsus on maailmas aktuaalne probleem, mille üle peavad järjepidevat diskussiooni nii poliitikakujundajad kui ka akadeemikud. Nii ei ole inimeste sissetulekute ebavõrdsuse kasvu probleemid mööda läinud isegi arenenud majandusega riikidest, kuid arengu- ning siirderiikides on probleem veelgi laiaulatuslikum ning tõsisem. Probleemide hulk, mida toob kaasa järjest süvenev sissetulekute ebavõrdsus arengu- ning siirderiikides on laiahaardeline ning mitmekesine, mistõttu arvatakse, et sissetulekute ebavõrdsus võib suure tõenäosusega põhjustada lähema kümne aasta jooksul maailmas olulist kahju. Nii teaduskirjanduses kui ka poliitilisel maastikul valitseb diskussioon selle üle, kas sissetulekute ebavõrdsuse allikaks on pigem riigisisene poliitika või tegu on siiski globaliseerumise näol maailmas aset leidnud loomulike arengutega. Siit tulenevalt oli bakalaureusetöö eesmärk uurida globaliseerumise majandusliku dimensiooni ning sissetulekute ebavõrdsuse vahelisi seoseid arengu- ning üleminekujärgus majandusega riikides. Töös püstitati hüpotees: mida globaliseerunum on majandus, seda väiksem on sissetulekute ebavõrdsus arengu- ning siirderiikides tulenevalt olemasolevatest teoreetilistest käsitlustest ning varasemate empiiriliste uuringute tulemustest. Püstitatud hüpoteesi kontrollimiseks viis autor läbi korrelatsioonanalüüsi kui ka mitmese regressioonanalüüsi abil modelleerimise. Valimisse kuulus kokku 53 arengu- ning siirderiiki 12 erinevast regioonist. Tulemused näitasid, et majanduslikku globaliseerumisprotsessi iseloomustavad avatud kaubavahetus ning välismaised otseinvesteeringud ei ole arengu- ning siirderiikides sissetulekute ebavõrdsust tekitavateks teguriteks ning viimaseid saab hoopis pidada sissetulekute ebavõrdsust vähendavateks mõjuriteks. Saadud uurimistulemused on kasulikud mõistmaks paremini kompleksse sissetulekute ebavõrdsuse probleemi olemust arengu- ning siirderiikides. Samuti võiksid saadud tulemused aidata kaasa arengu- ning siirderiikides tõhusa poliitika loomisele, eesmärgiga toetada sissetulekute ebavõrdsuse probleemiga edukamat toimetulekut.http://www.ester.ee/record=b5144161*es

Распространенность болезни Помпе у пациентов с идиопатической гиперкреатинкиназемией и слабостью поясно-конечностных мышц (анализ 3076 случаев)*

.Проведен проспективный скрининг дефицита фермента кислой α-глюкозидазы (GAA) европейской когорты пациентов с гиперкреатинкиназемией (гиперКК) и / или слабостью поясно-конечностных мышц (СПКМ) неустановленной этиологии с помощью метода сухого пятна крови (dry blood spot, DBS).Материалы и методы. Образцы DBS были собраны у 3076 взрослых пациентов, проходивших обследование в 7 немецких и британских нервно-мышечных центрах. Все образцы были исследованы на дефицит GAA методом флуорометрии. При выявлении пониженной ферментативной активности определяли наличие мутации гена GAA.Результаты. Из 3076 образцов DBS в 232 (7,6 %) случаях обнаружена низкая ферментативная активность GAA. У 55 (24 %) из 232 пациентов наблюдали изолированную гиперКК, а у 176 (76 %) – гиперКК и СПКМ. При комбинации 2 признаков у 94 % больных активность GAA была снижена. Мутационный анализ выявил мутации гена GAA у 74 (2,4 %) пациентов, при этом 70 больных были гетерозиготными по распространенной мутации сайта сплайсинга гена GAA c.-32-13T>G. У пациентов с подтвержденной болезнью Помпе основной симптомокомплекс состоял из СПКМ (85,3 %) в сочетании с дыхательной недостаточностью (61 %). У 12,0 % больных наблюдали изолированную гиперКК, а у 2,7 % – гиперКК и дыхательную недостаточность.Заключение. В большой когорте пациентов с гиперКК и / или СПКМ  распространенность болезни Помпе с поздним началом составляет 2,4 %, что требует проведения целевого скрининга активности GAA у пациентов с гиперКК и / или СПКМнеустановленной этиологии

A European research agenda for somatic symptom disorders, bodily distress disorders, and functional disorders: Results of an estimate-talk-estimate delphi expert study

Background: Somatic Symptom Disorders (SSD), Bodily Distress Disorders (BDD) and functional disorders (FD) are associated with high medical and societal costs and pose a substantial challenge to the population and health policy of Europe. To meet this challenge, a specific research agenda is needed as one of the cornerstones of sustainable mental health research and health policy for SSD, BDD, and FD in Europe. Aim: To identify the main challenges and research priorities concerning SSD, BDD, and FD from a European perspective. Methods: Delphi study conducted from July 2016 until October 2017 in 3 rounds with 3 workshop meetings and 3 online surveys, involving 75 experts and 21 European countries. EURONET-SOMA and the European Association of Psychosomatic Medicine (EAPM) hosted the meetings. Results: Eight research priorities were identified: (1) Assessment of diagnostic profiles relevant to course and treatment outcome. (2) Development and evaluation of new, effective interventions. (3) Validation studies on questionnaires or semi-structured interviews that assess chronic medical conditions in this context. (4) Research into patients preferences for diagnosis and treatment. (5) Development of new methodologic designs to identify and explore mediators and moderators of clinical course and treatment outcomes (6). Translational research exploring how psychological and somatic symptoms develop from somatic conditions and biological and behavioral pathogenic factors. (7) Development of new, effective interventions to personalize treatment. (8) Implementation studies of treatment interventions in different settings, such as primary care, occupational care, general hospital and specialty mental health settings. The general public and policymakers will benefit from the development of new, effective, personalized interventions for SSD, BDD, and FD, that will be enhanced by translational research, as well as from the outcomes of research into patient involvement, GP-patient communication, consultation-liaison models and implementation. Conclusion: Funding for this research agenda, targeting these challenges in coordinated research networks such as EURONET-SOMA and EAPM, and systematically allocating resources by policymakers to this critical area in mental and physical well-being is urgently needed to improve efficacy and impact for diagnosis and treatment of SSD, BDD, and FD across Europe