Axialer Verlauf der Geschwindigkeit in Luft-Freistrahlen

Zusammenfassung Die bisher bekannten Beziehungen zur Berechnung des axialen Geschwindigkeitsverlaufs in isothermen Luft-Freistrahlen gelten nur für das Strahlende etwa im Gebiet von x/d>50, in dem die Reynoldszahl keinen Einflu? mehr auf den Geschwindigkeits-oder Impulsabfall hat. In dem Gebiet4<x/d<50 nimmt das Verh?ltnis mit wachsender Reynoldszahl bis zu einer Grenz-Reynoldszahl zu. Durch Definition einer axialen Halbwertl?nge x_0,5 (x_0,5=x bei ) wurde eine Beziehung gefunden, die den Einflu? der Reynoldszahl am Strahlanfang berücksichtigt. Mitteilung aus dem Engler-Bunte-Institut, Bereich Feuerungstechnik, der Universit?t Karlsruhe (TH), Direktor des Instituts: Prof. Dr.-Ing. R. Günther.     

Multiple models and mental illnesses: A rejoinder to "Failure of a moral enterprise: Attitudes of the public toward mental illness" by T. R. Sarbin and J. C. Mancuso.

Critically analyzes the T. R. Sarbin and J. D. Mancuso (see record 1971-04081-001) report. Data are presented indicating that the public is (a) generally accepting of the medical model of mental illness; (b) optimistic about prognosis; and (c) able to identify the simple schizophrenic, the alcoholic, and the juvenile character disorder as mentally ill and in need of medical care. The public does not place a sizable social distance between themselves and those labeled mentally ill. These data contradict the claims advanced for a unitary social deviancy model. It is argued that the medical model is neither rejected by the public nor discredited by current research. The need is not for the abandonment of medical and psychological models which have already demonstrated formidable heuristic value; what is needed is recognition that there are many different kinds of mental illnesses and that multiple models may consequently have value. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Turbulenz in isothermen Freistrahlen

Zusammenfassung Die Str?mungsvorg?nge in turbulenten Strahlen wurden theoretisch und experimentell untersucht. Ausgehend von den Ans?tzen nach H. Reichardt und L. Prandtl lieferte die Theorie für den Fall eines isothermen, homogenen Freistrahls die ?rtlichen Werte der Schwankungsgeschwindigkeit, der scheinbaren kinematischen Viskosit?t und der turbulenten Schubspannung. Die berechneten Verteilungen stimmen mit den in isothermen Luftstrahlen gemessenen Werten und mit den aus dem Schrifttum bekannten Beziehungen befriedigend überein. Mitteilung aus dem Institut für Gastechnik, Feuerungstechnik und Wasserchemie der Universit?t Karlsruhe (TH); Auszug aus der von der Fakult?t für Maschinenbau und Verfahrenstechnik der Universit?t Karlsruhe (TH) genehmigten Dissertation des Verfassers.     

Konzentrationsfelder in isothermen Luft-Freistrahlen

Zusammenfassung Der turbulente Vermischungsproze? in einem Freistrahl, in dem eine Düsenstr?mung sich in einem ruhenden Umgebungsmedium ausbreitet, kann durch experimentelle Ermittlung der lokalen Stoffverteilung besser begründet werden. In isothermen Luft-Freistrahlen wurden unter Verwendung der Laser-Streulichtmethode Mittel-und Schwankungswerte der Konzentration gemessen und daraus die ?rtlichen Turbulenzintensit?ten ermittelt. Durch Vergleich mit Geschwindigkeitsmessungen wurde eine Abh?ngigkeit der turbulenten Schmidtzahl von der Reynoldszahl gefunden. Dr.-Ing.I. Ebrahimi war bei Abfassung des Beitrags Alexander-von-Humboldt-Stipendiat an diesem Institut. Die Verfasser danken Herrn Prof. Dr.-Ing.R. Günther für die Unterstützung dieser Arbeit. Weiterer Dank gilt der Deutschen Forschungsgemeinschaft für die Bereitstellung von Me?ger?ten, die diese Untersuchungen erm?glichten. Au?erdem sei der Alexandervon-Humboldt-Stiftung für die Gew?hrung eines Dozentenstipendiums herzlich gedankt.     

Operation Homecoming.

Describes the military's "Operation Homecoming" for Vietnam war veterans and argues that the military's effort to be helpful (delaying reentry into society and discouraging fanfare) was unnecessary and harmful. The hero's welcome provides a means of relief from guilt felt over killing, destruction, and activities not normally tolerated by society. (0 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Different finite element techniques to predict welding residual stresses in aluminum alloy plates

This study is a 3D thermomechanical finite element (FE) analysis of a single-pass and butt-welded work-hardened aluminum (Al) 5456 plates. It aims to validate the use of FE welding simulations to predict residual stress states in assessing the integrity of welded components. The predicted final residual stresses in the plate from the FE simulations are verified through comparison with experimental measurements. Three techniques are used to simulate the welding process. In the first two approaches, welding deposition is applied by using element birth and interaction techniques. In the third approach, the entire weld zone is simultaneously deposited. Results show a value at approximately the yield strength for longitudinal residual stresses of the welded center of the butt-welded Al alloy plates with a thickness of 2 mm. Considering the application of a comprehensive heat source, along with heat loss modeling and the temperature-dependent properties of the material, the approach without deposition predicts a reasonable distribution of residual stresses. However, the element birth and interaction techniques, compared with the no-deposit technique, provide more accurate results in calculating residual stresses. Furthermore, the element interaction technique, compared with the element birth technique, exhibits higher efficiency and flexibility in modeling the deposition of welded metals as well as less modeling cost.     

Crack shape developments for LBB applications

The flaw shape during sub-critical crack propagation (fatigue or stress corrosion) is important in order to estimate the crack opening area and leak rate at breakthrough and for the leaking crack. The ability to detect this leak rate is one of the cornerstones in the leak before break philosophy. In this study, the crack shape development is analysed and predicted using modern FEM techniques. The predictions are benchmarked against available fatigue experiments. Recommendations are given for crack shapes for both surface cracks and through-wall cracks in pipes and plates, and for sub-critical crack propagation as well as ductile tearing loading.     

Effect of the welding heat input on residual stresses in butt-welds of dissimilar pipe joints

This study used finite element techniques to analyse the thermo-mechanical behaviour and residual stresses in dissimilar butt-welded pipes. The residual stresses at the surface of some weld specimens were measured experimentally by using the hole-drilling method. The results of the finite element analysis were compared with experimentally measured data to evaluate the accuracy of the finite element modelling. Based on this study, a modelling procedure with reasonable accuracy was developed. The developed finite element modelling was used to study the effects of welding heat input on magnitude and distribution of welding residual stresses in butt-welded pipes made of ferritic and austenitic steels. The hoop and axial residual stresses in dissimilar pipe joints of 8 mm thick for V-groove shape were studied. It is shown that the welding heat input has a significant effect on magnitude and distribution of residual stresses in the stainless steel side of the studied joints.     

Effect of the weld groove shape and pass number on residual stresses in butt-welded pipes

This study used finite element techniques to analyze the thermo-mechanical behaviour and residual stresses in butt-welded pipes. The residual stresses were also measured in some welds by using the Hole-Drilling method. The results of the finite element analysis were compared with experimentally measured data to evaluate the accuracy of the finite element modelling. Based on this study, a finite element modelling procedure with reasonable accuracy was developed. The developed FE modelling was used to study the effects of weld groove shape and weld pass number on welding residual stresses in butt-welded pipes. The hoop and axial residual stresses in pipe joints of 6 and 10 mm thickness of different groove shapes and pass number were studied. It is shown that these two parameters may have significant effects on magnitude and distribution of residual stresses in welded pipes.