A Systematic Methodology for Populating the Aircraft Thermal Management System Architecture Space

Presented at AIAA SCITECH 2021The aircraft thermal management system functions to provide suitable working conditions for pilot, crew, passengers, and the other aircraft systems. The additional weight, drag and power consumption caused by it greatly influences the performance of the aircraft. However, due to rising heat load of emerging novel aircraft concepts, traditional design approaches which rely on data and empirical equations may not apply to the future thermal management systems. Many existing literature which tried to identify the optimal thermal management system architectures only considered limited architecture space where the candidates were pre-selected in terms of experience or intuition. Therefore, viable but non-intuitive architectures may not be included in the design space. To fill this gap, this paper proposes a behavior-based backtracking methodology to systematically populate the architecture space by enumerating both intuitive and non-intuitive architectures. Thermal management requirements for traditional and novel configurations are used to generate the architectures. By comparing the generated architectures with existing ones, this paper validates that the proposed methodology is capable of generating both intuitive and non-intuitive architectures

Heliumverfluessigung und Kryorefrigeratoren in der Physikalisch-Technischen Bundesanstalt (PTB) Einsatz und eigene Entwicklungsbeitraege

An overview is given on the development and trends of refrigerator techniques, and the fundamentals of gas refrigerating machines are outlined. Reminescences on history and development range from the first helium liquefaction (Meissner, 1925) to the comparison of the Leybold helium refrigerator with the Gifford-McMahon refrigerator. PTB-own development and activities comprise the long term operation behaviour of small scale stirling refrigerators, the glas low power cryo-refrigerator, the pressure wave generator, the experimental stirling refrigerator and the refrigerator drive. It is concluded that on account of failures in the long term operation and of the perturbation of electronic systems by moving machine components, the international trend points away from the stirling principle, a possible substitute being the pulse-tube-refrigerator. (WEN)SIGLEAvailable from TIB Hannover: RN 3295(52) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Effects of protein on fermentation and fiber disappearance in vitro using an equine cecal inoculum

The purpose of this experiment is to determine the effects of varying protein sources on in vitro fermentation characteristics and fiber disappearance utilizing an equine cecal fluid inoculum. Experimental design consisted of a completely randomized design with 4 replications (horse). Treatments consisted of protein source (no protein, casein, whey, soybean meal, plasma, L-lysine, and fishmeal). Cecal fluid was acquired from 4 cecally cannulated horses consuming a diet of smooth bromegrass hay (1.5% BW) and commercial concentrate (0.5% BW). Strain and stratified cecal fluid was mixed with McDougal’s buffer, substrates, and respective treatments and then incubated for 48 hours in a shaking incubator at 39°C. Gas pressure was continuously recorded and terminal concentrations of DM, OM, NDF, ADF, and VFA (acetate, propionate, butyrate, Valerate and Isovalerate) were determined. Compared to the control, casein, soybean meal, whey, plasma, L-lysine, and fishmeal increased (P < 0.05) DM disappearance and acetate production. NDF and ADF disappearance was greater (P < 0.05) for all protein sources when compared to control. Total VFA concentrations increased (P < 0.05) with all protein sources when compared to the control. Results from this experiment demonstrate that fiber disappearance of a low quality can be enhanced via supplemental protein, regardless of source. Similarly, protein increases VFA production which can be attributed to greater microbial activity and/or populations. Protein sources with greater solubility appear to be more effective at improving fiber disappearance and VFA production although this observation was not statistically significant. Future work in vivo is warranted to determine if the same effects would be observed in the equine

Untersuchungen an Werkstoffen fuer Stirling-Kleinrefrigeratoren im Langzeitbetrieb Abschlussbericht

Available from TIB Hannover: FR 5942+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman