An approach to metal fatigue

Cumulative fatigue damage based on investigation of fatigue limit associated with crack, crack propagation rate, and stress interaction cycle in metal

Characterization of Iridium Coated Rhenium Used in High-Temperature, Radiation-Cooled Rocket Thrusters

Materials used for radiation-cooled rocket thrusters must be capable of surviving under extreme conditions of high-temperatures and oxidizing environments. While combustion efficiency is optimized at high temperatures, many refractory metals are unsuitable for thruster applications due to rapid material loss from the formation of volatile oxides. This process occurs during thruster operation by reaction of the combustion products with the material surface. Aerojet Technical Systems has developed a thruster cone chamber constructed of Re coated with Ir on the inside surface where exposure to the rocket exhaust occurs. Re maintains its structural integrity at high temperature and the Ir coating is applied as an oxidation barrier. Ir also forms volatile oxide species (IrO2 and IrO3) but at a considerably slower rate than Re. In order to understand the performance limits of Ir-coated Re thrusters, we are investigating the interdiffusion and oxidation kinetics of Ir/Re. The formation of iridium and rhenium oxides has been monitored in situ by Raman spectroscopy during high temperature exposure to oxygen. For pure Ir, the growth of oxide films as thin as approximately 200 A could be easily detected and the formation of IrO2 was observed at temperatures as low as 600 C. Ir/Re diffusion test specimens were prepared by magnetron sputtering of Ir on Re substrates. Concentration profiles were determined by sputter Auger depth profiles of the heat treated specimens. Significant interdiffusion was observed at temperatures as low as 1000 C. Measurements of the activation energy suggest that below 1350 C, the dominant diffusion path is along defects, most likely grain boundaries, rather than bulk diffusion through the grains. The phases that form during interdiffusion have been examined by x ray diffraction. Analysis of heated test specimens indicates that the Ir-Re reaction produces a solid solution phase of Ir dissolved in the HCP structure of Re

Staging disassembly : incubating post-industrial renewal

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 2009.Includes bibliographical references (p. 72-73).Over the past five decades, the American urban industrial landscape has become marginalized as the expanding global economy has sought international markets for manufacturing. At the agency of the user-as-investor, this proposal seeks to re-manufacture the post-industrial site to explore the problem of how to effectively reclaim salvaged materials for on-site reuse. As a critique of speculative, clean-slate development, the thesis will explore an incremental disassembly and phased reorganization of a site in Brooklyn at the material and urban scale. Through on-site implementation of manufacturers and automated tooling, this project will speculate on means of creating new value for salvaged materials. The resulting form is a vaulted roofscape that supports public access and leisure space while creating a local strategy for post-industrial renewal.by Eliot Falk Stulen.M.Arch

Å bli mer forankret i seg selv. En studie om væremåter og handlingsmuligheter i psykomotorisk fysioterapi.

Bakgrunn: Studier innen psykomotorisk fysioterapi belyser at pasienter får økt kroppskontakt og kroppsbevissthet, og hvordan behandling kan fremme endring og nye handlinger. Det er få beskrivelser av hvordan fysioterapeuten og pasienten arbeider i behandling for å fremme nye handlinger. Hensikt: Målet med studien er å undersøke hvordan fysioterapeuten utforsker pasienten sine vaner og væremåte og hvordan behandlingen kan fremme nye handlingsmuligheter hos pasienten. Metode: En kvalitativ studie basert på empiri fra video-observasjon av en behandlingstime, etterfulgt av intervju og samobservasjon av video-opptaket med fysioterapeuten. Resultatene baseres på handlingssekvenser som utvikler kunnskap om hvordan de arbeider for å fremme nye handlingsmuligheter hos pasienten. Resultater: Studien viser hvordan fysioterapeuten bruker massasje og nyanser av bevegelser for å utforske pasientens vaner og væremåte for å fremme nye handlinger. Studien gir et øyeblikksbilde av konkrete eksempler der pasienten handler på nye måter. Konklusjon: I denne behandlingstimen utvikler pasienten seg fra å begrense seg selv til å handle mer i tråd med egne behov. Pasienten opplever å stå på en ny måte og blir mer forankret i seg selv. Nøkkelord: Psykomotorisk fysioterapi, vaner, væremåter, handlingsmuligheter og klinisk praksis