Comparative analysis and optimization of technical and weight parameters of turbo-electric propulsion systems

According to Flightpath 2050, the aviation industry is aiming to substantially reduce emissions over the coming decades. One possible solution to meet these ambitious goals is by moving to hybrid-electric drivetrain architectures which require the electric components to be extremely lightweight and efficient at the same time. It has been claimed in several publications that cryogenic and in particular superconducting components can help to fulfill such requirements that potentially cannot be achieved with non-cryogenic components. The purpose of this work was to make a fair comparison between a cryogenic turbo-electric propulsion system (CEPS) and a non-cryogenic turbo-electric propulsion system (TEPS) on a quantitative level. The results on the CEPS were presented in detail in a previous publication. The focus of this publication is to present the study on the TEPS, which in conclusion allows a direct comparison. For both systems the same top-level aircraft requirements were used that were derived within the project TELOS based on an exemplary mission profile and the physical measures of a 220-passenger aircraft. Our study concludes that a CEPS could be 10% to 40% lighter than a TEPS. Furthermore, a CEPS could have a total efficiency gain of up to 18% compared to a similar TEPS

The Whole Counsel of God: A Tribute to E. Herbert Nygren

Herb Nygren has served Taylor University faithfully for over twenty years. As chair of the Department of Biblical Studies, Christian Education, and Philosophy, he has modelled sound teaching and solid scholarship. Upon retirement, he leaves us a legacy of dedication, service, and love for Christ. The members of his department offer these essays as a small token of our esteem.https://pillars.taylor.edu/ayres-collection-books/1019/thumbnail.jp

A Novel, Non-Apoptotic Role for Scythe/BAT3: A Functional Switch between the Pro- and Anti-Proliferative Roles of p21 during the Cell Cycle

BACKGROUND: Scythe/BAT3 is a member of the BAG protein family whose role in apoptosis has been extensively studied. However, since the developmental defects observed in Bat3-null mouse embryos cannot be explained solely by defects in apoptosis, we investigated whether BAT3 is also involved in cell-cycle progression. METHODS/PRINCIPAL FINDINGS: Using a stable-inducible Bat3-knockdown cellular system, we demonstrated that reduced BAT3 protein level causes a delay in both G1/S transition and G2/M progression. Concurrent with these changes in cell-cycle progression, we observed a reduction in the turnover and phosphorylation of the CDK inhibitor p21, which is best known as an inhibitor of DNA replication; however, phosphorylated p21 has also been shown to promote G2/M progression. Our findings indicate that in Bat3-knockdown cells, p21 continues to be synthesized during cell-cycle phases that do not normally require p21, resulting in p21 protein accumulation and a subsequent delay in cell-cycle progression. Finally, we showed that BAT3 co-localizes with p21 during the cell cycle and is required for the translocation of p21 from the cytoplasm to the nucleus during the G1/S transition and G2/M progression. CONCLUSION: Our study reveals a novel, non-apoptotic role for BAT3 in cell-cycle regulation. By maintaining a low p21 protein level during the G1/S transition, BAT3 counteracts the inhibitory effect of p21 on DNA replication and thus enables the cells to progress from G1 to S phase. Conversely, during G2/M progression, BAT3 facilitates p21 phosphorylation by cyclin A/Cdk2, an event required for G2/M progression. BAT3 modulates these pro- and anti-proliferative roles of p21 at least in part by regulating cyclin A abundance, as well as p21 translocation between the cytoplasm and the nucleus to ensure that it functions in the appropriate intracellular compartment during each phase of the cell cycle.Dissertatio

Electromagnetic design of a superconducting electric machine with bulk HTS material

The use of high-temperature superconductors in electric machines offers potentially large gains in performance compared to conventional conductors, but also comes with unique challenges. Here, the electromagnetic properties of superconducting electric machines with bulk HTS trapped-field magnets in the rotor and conventional copper coils in the stator are investigated. To this end, an analytical model of the electromagnetic field in radial air-gap synchronous electric machines is developed and validated, taking into account the specific difficulties that occur in the treatment of machines with bulk HTS. Using this model, the influence of pole pair number, stator winding thickness, rotor surface coverage, and air gap width on the machine's Esson coefficient is calculated. In contrast to numerical simulations, the method presented here can provide results within minutes, making it particularly useful for work in early development and systems engineering, where large parameter spaces must be investigated quickly

Dicer1-mediated miRNA processing shapes the mRNA profile and function of murine platelets

Human platelets contain microRNAs (miRNAs) and miRNA processing machinery, but their contribution to platelet function remains incompletely understood. Here, we show that murine megakaryocyte (MK)-specific knockdown of Dicer1, the ribonuclease that cleaves miRNA precursors into mature miRNAs, reduces the level of the majority of miRNAs in platelets. This leads to altered platelet messenger RNA (mRNA) expression profiles and mild thrombocytopenia. Fibrinogen receptor subunits Itga2b (αIIb) and Itgb3 (β3) mRNAs were among the differentially expressed transcripts that are increased in platelets lacking Dicer1. Argonaute 2 (Ago2), a member of the miRNA silencing complex, co-immunoprecipitated with αIIband β3mRNAs in wild-type platelets. Furthermore, co-immunoprecipitation experiments suggested reduced αIIb/β3/Ago2 complexes in miRNA-deficient platelets. These results suggested that miRNAs regulate both integrin subunits. Subsequent 3' untranslated region luciferase reporter assays confirmed that the translation of both αIIband β3mRNAs can be regulated by miRNAs miR-326, miR-128, miR-331, and miR-500. Consistent with these molecular changes, the deletion ofDicer1resulted in increased surface expression of integrins αIIband β3, and enhanced platelet binding to fibrinogen in vivo and in vitro. Heightened platelet reactivity, shortened tail-bleeding time, and reduced survival following collagen/epinephrine-induced pulmonary embolism were also observed in Dicer1-deficient animals. CombinedPf4-cre-mediated deletion of Drosha and Dicer1 did not significantly exacerbate phenotypes observed in single Dicer1 knockout mice. In summary, these findings indicate that Dicer1-dependent generation of mature miRNAs in late-stage MKs and platelets modulates the expression of target mRNAs important for the hemostatic and thrombotic function of platelets.Jesse W. Rowley, Stéphane Chappaz, Aurélie Corduan, Mark M. W. Chong, Robert Campbell ... Benjamin T. Kile ... et al

Experimental Study of the Effect of TiN–Zn Coated High-Speed Steel Cutting Tool on Surface Morphology of AL1060 Alloy During Machining Operation

In machining operations, surface morphology is a significant parameter in developing mechanical components, as the level of the surface roughness gives the consumer the notion of whether the product is well developed or not. Also, the surface roughness of the mechanical component will affect the component during machining operations. The application of coatings in cutting tools is very significant, as coatings will help in improving the cutting tool life as well as protect it from rapid wear and corrosion rate. This research work focuses on the investigation of the significance of TiN–Zn coatings on high-speed steel (HSS) when compared with non-coated HSS cutting tool on the surface morphology, machining parameters and machining time on 1060 aluminum alloy during the machining operation. Computer numerical control (CNC) program and excel software was employed to investigate the effects the Coated cutting tool, various depth of cut and such as 1, 1.5, 2, 2.5, and 3 mm and at a constant cutting speed of 1250 rpm, constant feed rate of 10 mm/rev, with machining time varies from 15 to 500 s on the machined surface morphology of the 1060 aluminum alloy. After each machining time, the average surface roughness was determined, from three-point of the work piece, that is the starting point, middle point, and the end point. The result shows that the TiN–Zn coated HSS cutting tool on the surface morphology of 1060 aluminum alloy was found to reduce surface roughness with about 15.5% and both minimum surface roughness of 0.96 and 1.06 μm was achieved for the TiN–Zn coated and uncoated HSS cutting tool, respectively, with cutting time of 15 s at 1 mm depth of cut, which is viable for machining operations