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  • Polymer and Materials Science  (4)
  • Architecture  (1)
  • Basilar artery stenosis  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Basilar artery disease —Clinical outcome and doppler sonographical follow-up (1988)
    Springer
    European archives of psychiatry and clinical neuroscience 237 (1988), S. 91-100 
    Details
    ISSN: 1433-8491
    Keywords: Basilar artery stenosis ; Basilar artery occlusion ; Continuous-wave Doppler sonography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the past 5 years we have investigated 29 patients with symptomatic basilar artery stenoses (14 cases) and occlusions (14) and a patent primitive trigeminal artery with thin-calibered basilar and vertebral arteries (1) using directional continuous-wave Doppler sonography of the vertebral arteries. A total of 19 patients survived, and 17 of them were clinically and sonographically reexamined after 40.4 ± 15.8 months (mean ± SD). Among the 8 patients with basilar stenoses, 6 — with no further transient ischemic attacks (TIAs) in the interval — exhibited an increase in the summed modified Pourcelot indices (relative end-diastolic flow velocities) of the vertebrals by 0.18 ± 0.16; the other 2 showed a decrease by 0.26 each, in 1 case temporally related to a TIA, in the 2nd case without further clinical deterioration. In the 8 survivors with basilar occlusions, 5 remained — by sonographic criteria — unchanged with summed modified Pourcelot indices of the vertebrals of 0.00, while 3 patients exhibited a slight increase in the summed modified Pourcelot indices of 0.13 ± 0.03. While the difference between the outcome of subsets of patients treated with regimens of 30,000–40,000 units heparin/day or phenprocoumon and less radical drugs were statistically not significant, the former regimen appeared clinically more efficacious in preventing further deterioration in approximately two-thirds of the patients affected. Due to the potential recurrence of neurological symptoms, a treatment period with phenprocoumon of 6 months after discharge from hospital appears justified. Due to these therapeutic efforts, approximately half of the patients initially affected survived with no or only a mild neurological deficit. Directional continuous-wave Doppler sonography is, in our opinion, a reliable technique for examining the short- and long-term changes in peripheral vascular resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00382372
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  • 2
    Electronic Resource
    Electronic Resource
    Graded Thermal Barrier Coating Systems for gas turbine applicationsDedicated to Prof. Wolfgang Bunk on the occasion of his 70th birthday (1997)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 28 (1997), S. 391-394 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Gradierte Wärmedämmschichtsysteme für Anwendungen in der GasturbineFortschrittliche Wärmedämmschichten tragen zu einer erhöhten Effektivität von Triebwerken bei. Ein bedeutsames Problem ist die thermische Instabilität von Verbundwerkstoffen bei den hohen Einsatztemperaturen. Interdiffusion, Oxidation und Sintereffekte begrenzen dabei die Lebensdauer der Schichten. Verschiedene Ansätze zu Verlängerung der Lebensdauer und/oder zur Erhöhung der Einsatztemperatur sind im System Substrat-Schutzschicht möglich. Einige Lösungen enthalten die Anwendung des Konzepts der gradierten Werkstoffe. Im folgenden werden mögliche Anwendungen gradierter Werkstoffe in Wärmedämmschichtsystemen vorgestellt sowie ein Überblick über aktuelle Forschungsergebnisse auf diesem Gebiet gegeben.
    Notes: Improved thermal barrier coatings can lead to increased engine operating efficiency. A significant problem is that multilayer systems are not thermally stable at elevated temperatures. Phenomena such as interdiffusion, oxidation and sintering take place, limiting coating lifetime. In order to extend lifetimes and/or increase service temperatures several modifications can be made to coating-substrate systems. Some solutions involve the utilization of the functionally graded material concept. In this paper, potential applications for functionally graded materials in thermal barrier coating systems are discussed, and research results are summarized providing an overview of the state-of-the-art.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19970280817
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  • 3
    Electronic Resource
    Electronic Resource
    Thermocyclic Behavior of Differently Stabilized and structured EB-PVD thermal barrier coatingsDedicated to Prof. Wolfgang Bunk on the occasion of his 70th birthday (1997)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 28 (1997), S. 370-376 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Thermowechselverhalten von EB-PVD Wärmedämmschichten mit unterschiedlicher Zusammensetzung und StrukturDurch das Elektronenstrahl-Verdatnpfungsverfahren (EB-PVD) werden spezifische, kolumnare Schutzschichten auf Gasturbinen- bauteilen erzeugt. Der hauptsächliche Vorteil dieser Struktur liegt in ihrer herausragenden Beständigkeit gegen Dehnungen, Erosion und Thermoschockbelastungen, was zu einer Lebensdauerverlän- gerung führt. Der Einfluß der chemischen Zusammensetzung so- wie der Mikrostruktur auf die Lebensdauer von EB-PVD Wärme- dämmschichten auf Zirkondioxidbasis wird in einem zyklischen Heißgas- sowie in einem Thermowechselversuch untersucht. Die Möglichkeit zur Herstellung von anwendungsangepaßten Wärme- dammschichten durch Parametervariation beim EB-PVD-Verfah- ren wird aufgezeigt. Das Strukturzonendiagramm für PVD-Verfahren wird weiterentwickelt, indem der Einfluß der Substratrotation auf die Ausbildung der Mikrostruktur eingearbeitet wird. Einige grundlegende Aspekte von Einquellen- und Zweiquellenverdamp- fung werden verglichen.
    Notes: The electron-beam physical vapor deposition (EB-PVD) process provides distinctive coatings of a unique columnar microstructure for gas turbine components. Main advantage of this structure is superior tolerance against straining, erosion and thermoshock, thus giving it a major edge in lifetime. This paper outlines the interaction between chemical composition and microstructural evolution EB-PVD zirconia-based thermal barrier coatings (TBCs) and their respective lifetimes in cyclic burner rig and furnace tests. Customizing TBC microstructure by adjusting EB-PVD processing parameters is emphasized. A structural zone diagram for PVD is modified by interconnecting the influence of substrate rotation with microstructural evolutions. Finally, some basic aspects of single source and dual source evaporation are compared.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19970280811
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  • 4
    Electronic Resource
    Electronic Resource
    Design and Properties of Thermal Barrier Coatings for advanced turbine enginesDedicated to Prof. Wolfgang Bunk on the occasion of his 70th birthday (1997)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 28 (1997), S. 357-362 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Herstellung und Eigenschaften von Wärmedämmschichten für fortschrittliche GasturbinenDie Verbesserung des Wirkungsgrades stationärer wie auch fliegender Gasturbinen erfordert eine Erhöhung der Prozeßtemperaturen und damit auch der Werkstoffeinsatztemperaturen. Trotz aufwendiger Kühlung und einkristalliner Bauweise stoßen die höchstbeanspruchten rotierenden Teile in der Turbine - die Turbinenschaufeln - heute an Einsatzgrenzen, die durch den Schmelzpunkt der Ni-Superlegierungen vorgegeben sind. Hier haben Wärmedämmschichten eine zentrale Bedeutung erlangt. Aufgrund der im Vergleich zum Substrat äußerst geringen Wärmeleitfähigkeit dieser keramischen Schichten lassen sich bei innengekühlten Turbinenschaufeln Gastemperaturerhöhungen von bis zu 150°C erzielen. Wärmedämmschichten werden primär durch thermisches Spritzen (PS) oder Elektronenstrahlverdampfung (EB-PVD) hergestellt. Während PS kostengünstiger ist, weisen EB-PVD-Wärmedämmschichten ein überlegenes Schadenstoleranzverhalten auf. Zudem werden durch das Aufdampfen die Kühlluftbohrungen nicht verstopft, und aerodynamisch glatte Oberflächen bleiben erhalten. Zum Schluß wird ein Ausblick auf Forschungs- und Entwicklungstrends in der Wärmedämmschichttechnologie gegeben.
    Notes: The efficiency and performance of advanced aircraft turbines can be markedly increased if higher gas temperatures are used. Although the highly loaded blades and vanes in the high pressure turbine are heavily cooled, today's substrate materials are unable to provide sufficient strength in the temperature range up to 1500°C and above. If thermal barrier coatings (TBCs) are applied on superalloy turbine blades a substantial temperature drop of the parts can be achieved. The resulting increase in efficiency comes from reduced cooling and/or increased gas turbine inlet temperatures of up to 150°C. TBCs are either processed by plasma spraying (PS) or electron beam physical vapour deposition (EB-PVD). While PS is lower in cost EB-PVD leads to superior strain and thermoshock tolerant coatings. Furthermore, cooling hole closure of turbine blades and vanes is prevented and aerodynamic design maintained. Finally, future research and development needs in TBC technology are stressed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19970280807
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  • 5
    Electronic Resource
    Electronic Resource
    Architecture in cortical bone and ultrasound transmission velocity (1993)
    Springer
    Clinical rheumatology 12 (1993), S. 364-367 
    Details
    ISSN: 1434-9949
    Keywords: Ultrasound ; Cortical bone ; Mechanical Properties ; Architecture ; Modulus of Elasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The square of ultrasound transmission velocity in a material is correlated to the modulus of elasticity, which is an indicator of its mechanical properties. This might make the measurement of ultrasound transmission velocity useful in the noninvasive diagnosis of bone diseases. Bone, however, is not an isotropic material but is architecturally structured. The aim of our study was to investigate and especially to quantify the influence of architecture in cortical bone on ultrasound transmission velocity. Twenty-two rectangular, flat specimens of cortical bone were prepared from diaphysis of fresh pig radius. Ultrasound transmission velocity was measured parallel and perpendicular to direction of Haversian channels. It was found to be 3647 ± 41 m/s parallel to and 2821 ± 29 m/s perpendicular to Haversian channels respectively (p〈0.001). Our results clearly indicate that there is an important influence of architecture in cortical bone on ultrasound transmission velocity which has to be taken into account in its clinical use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02231581
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  • 6
    Electronic Resource
    Electronic Resource
    Environmental statistics and data analysis. Von Wayne R. Ott, 336 S., CRC Press, Lewis Publishers Boca Raton 1995, £55.00, ISBN 0-87371-848-8 (1997)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 48 (1997), S. 463-463 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19970480716
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