Beitrag zur asynchronen Linearmaschine mit ortsabhängiger Sekundärleitfähigkeit

Übersicht Bei asynchronen Linearmaschinen, wie dem Langstatormotor mit diskontinuierlicher Statoranordnung und steuerbarem Sekundärteil für Schnellbahnantriebe, dem Flüssigmetall-MHD-Wandler oder dem Sektormotor ist eine Herabsetzung der Sekundärleitfähigkeit außerhalb des Statorbereiches möglich. Der Einfluß einer solchen ortsabhängigen Leitfähigkeit des Sekundärteils auf die Feld- und Stromverteilung und auf die Betriebskennlinien wird untersucht.

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Contents Linear induction machines, such as the high speed ground transportation motor with discontinuously arranged stators along the guideway and controllable secondary on the train, further the liquid metal MHD convertor or the sector motor allow to be operated with reduced conductivity of the secondary outside the stator. The influence of a stator position dependent conductivity of the secondary on field and current distribution and on the characteristics is analysed.

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Die Verfasser danken der Deutschen Forschungsgemeinschaft für die finanzielle Unterstützung des Forschungsvorhabens.     

Concentrations of fat and plasma 5alpha-androstenone and plasma testosterone in boars selected for rate of body weight gain and thickness of back fat during growth, sexual maturation and after mating

The levels of 5alpha-androstenone and testosterone in peripheral plasma and 5alpha-androstenone in fat collected from 18 boars selected according to thickness of back fat and rate of gain were evaluated. Sampling was started when the animals were about 100 days of age and samples were collected every 14 days until the boars were about 240 days old. The steroid profiles varied considerably between boars, although an increase in steroid levels was found in most animals with the onset of adolescence. The regression line for the level of 5alpha-androstenone in fat and the age of the animals in days was found to be y = 0.02x-1-31. High coefficients of correlation were found between the concentration of 5alpha-androstenone in peripheral plasma and fat (r = 0-78) and between levels of 5alpha-androstenone and testosterone in peripheral plasma (r = 0-64). Levels of 5alpha-androstenone in peripheral plasma above about 15 ng/ml were usually accompanied by a heavy accumulation of 5alpha-androstenone in adipose tissue. The use of four of the boars for mating resulted in increased steroid levels in peripheral plasma and fat. Significantly higher levels of 5alpha-androstenone and testosterone were found in the peripheral plasma of boars selected for fatness and a low rate of gain than in boars selected for low back-fat thickness and a high rate of gain.     

Synthesis and characterization of a catechol metabolite of glutethimide (Doriden) in human urine

Adenovirus type 2 DNA, specifically labeled at the termini for DNA replication, was prepared by isolation of viral DNA molecules which were completed during short pulses with 3H-thymidine. The distribution of radioactivity in the two complementary strands at the termini for DNA replication was determined by liquid phase hybridization and gelelectrophoresis. At the right-hand terminus, nearly all radioactivity was found in the viral h strand, whereas at the left-hand terminus, most radioactivity was confined to the viral l strand. The results suggest that both molecular ends serve as origins and termini for replication of adenovirus type 2 DNA.     

Über den Einfluß von Ständerdämpfungskreisen auf die Stromwendung von Gleich- und Wechselstrommaschinen mit Wendepolen

Übersicht Die Stromwendungsgüte von Gleichstrom- und Wechselstrom-Kommutatormaschinen läßt sich mit Hilfe von Windungen im Wendepolluftspalt verbessern, in die Kondensatoren eingeschaltet sind. Die Verbreiterung der funkenfreien Zonen wird abhängig von der Kapazität und der Bürstenbreite an einer kompensierten Gleichstrommaschine gemessen und anhand eines vereinfachten Ersatzschaltbildes rechnerisch gedeutet. Die dämpfende Wirkung des massiven Ständerjoches und der Feldwicklung werden aus den Meßergebnissen rechnerisch näherungsweise bestimmt. Die prozentualen Zahlenwerte haben für einfache Abschätzungen allgemeinen Wert, da die Streufaktoren größerer Maschinen nur geringfügig voneinander abweichen.

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Summary The commutation efficiency of d. c. and a. c. commutator machines can be improved by the presence of windings in the interpole airgap into which capacitors are switched. The increase in width of the spark-free zones, which is dependent on the capacitance value and the brush width, is measured on a compensated d. c. machine and calculated by means of a simplified equivalent circuit diagram. The damping effect of the solid stator yoke and the field winding is approximately calculated from the measured results. The percentage numerical values are of general value for simple estimations, since the leakage coefficients of larger machines vary only by insignificant amounts.

     

Zur Hysterese einer auf Zug beanspruchten Schraubverbindung

Zusammenfassung Die Hysterese und die Energiedissipation in einer auf Zug beanspruchten Schraubverbindung werden rechnerisch und experimentell ermittelt. Das Rechenmodell besteht aus Zugst?ben mit konstanter, parabelf?rmiger oder polynomartig verteilter Querlast in der Kontaktzone als Folge der Schraubenanpre?kraft. Wenn eine Zuglast wirkt, verschieben sich die St?be relativ zueinander. Die abgeleiteten Verschiebungs-Last-Funktionen und die Verlustarbeiten h?ngen von der gew?hlten Querkraftverteilung ab. Rechnung und Experiment werden mit Hilfe der Verlustarbeit in Abh?ngigkeit von der Zugkraft quantitativ verglichen. Die beste übereinstimmung ergibt sich für parabelf?rmige und polynomartige Querlast. Auch die rechnerisch und experimentell ermittelten Formen der Hystereseschleifen unterscheiden sich nur wenig voneinander. Mit dem Rechenmodell k?nnen zus?tzliche Zwischenzyklen bei Be- und Entlastungsvorg?ngen erfa?t werden. Akad. Oberrat     

Direct chemical analysis of solids by laser ablation in an ion storage time-of-flight mass spectrometer

A laser ablation/ionization mass spectrometer system is described for the direct analysis of solids, particles, and fibers. The system uses a quadrupole ion trap operated in an ion storage mode, coupled with a reflectron time-of-flight mass spectrometer). The sample is inserted radially into the ring electrode, and an imaging system allows direct viewing and selected analysis of the sample. Measurements identified trace contaminants of Ag, Sn, and Sb in a Pb target with single laser shot experiments. Resolution (m/Delta m) of 1500 and detection limits of approximately 10 pg have been achieved with a single laser pulse. The system configuration and related operating principles for accurately measuring low concentrations of isotopes are described.     

Elbphilharmonie Hamburg – Grundsätzliche Überlegungen zur Zusammenarbeit Ingenieur – Architekt

Elbphilharmonie Hamburg – Fundamental considerations to co‐operation between engineer and architect At present the authorization (?) planning for the Elbphilharmonie runs in Hamburg. The project becomes up to the commencement of construction, which is planned already for at the beginning of 2007, further concretized and refined. The architectural idea to touch down on old, 1964 built dock silo a Philharmonic Concert Hall with luxury dwellings and a hotel was developed in the context of an investor project. This idea was so convincingly that it found now a very broad basis in the population and is now in the planning process, with the goal, this unique and for Hamburg important project not only to plan but also to build.     

Molecular dynamics study of the influence of functionalization on the elastic properties of single and multiwall carbon nanotubes

The effect of carboxylation on axial Young’s modulus of carbon nanotubes is investigated using a molecular dynamics (MD) approach. COMPASS force field is used to model the interatomic interactions in single wall (SWCNT) and multiwall carbon (MWCNT) with different amounts of –COOH groups attached to their surfaces. The results of the MD simulations show how an increase of the number of carboxylic groups on the CNT surface leads to a decrease on the Young moduli of the CNTs. The decrease of MWCNT Young’s modulus is found to be lower than in the case of SWCNT.     

Isolation of monoclonal antibodies monospecific for bovine kappa-casein

Bovine kappa-casein represents a major portion of the total protein present in milk and is required for formation of the caseinate micelles responsible for the transportation of both calcium and phosphorous. Two monoclonal antibodies directed against bovine kappa-casein have been isolated. Both monoclonal antibodies are highly specific for bovine kappa-casein. Western analysis of denatured kappa-casein suggests epitope specificity is, in part, conformationally dependent. Additional epitope mapping with chymosin and neuraminidase also suggest antibody binding is in the region of the amino acid sequence Pro-Thr-Thr at positions 92 to 94 and 134 to 136.     

Influence of temperature on pyrolysis of recycled organic matter from municipal solid waste using an activated olivine fluidized bed

Pyrolysis of an organic concentrate from municipal solid waste was carried out using a bench-scale fluidized bed reactor at 350-540 °C comparing Al₂O₃ with activated olivine sand as bed materials. A maximum oil yield of 50 wt.% was obtained using the activated olivine sand at 400 °C while only 45 wt.% was obtained at 500 °C using Al₂O₃. The bio-oils using activated olivine sand at 400 °C had an H/C ratio of 1.50 and O/C ratio of 0.37 and were less aromatic and less nitrogenous compare to the oils obtained using Al₂O₃ at 400 °C where the H/C ratio was 1.32 and the O/C ratio was 0.44. The aromatic compounds were found to be reduced while the aliphatic compounds increased in the oils generated using activated olivine sand. The calorific value of the bio-oil at 500 °C was 29 MJ/kg using activated olivine sand while the bio-oil using Al₂O₃ was 23 MJ/kg. The presence of iron, magnesium and other oxides probably promotes the removal of oxygen, which indicates that the activation energy of C―O bond breakage is reduced compared to the C―C bonds, thus promoting dehydration, decarboxylation and alkalation reactions to produce aliphatic fatty acid at lower temperatures.