Integration of the structural solver B2000++ in a multi-disciplinary process chain for aircraft design

Within the DLR project VicToria (2016 - 2020) multidisciplinary aircraft design process chains were developed to evaluate and optimize transport aircraft under a variety of different aspects such as aerodynamics, structural behaviour, flight control, etc. Aside from the different disciplines the process chains also combine analysis tools on different fidelity levels with the focus on sophisticated CFD and CSM methods based on Finite Element analyses [1]. For the transfer of aircraft parameters between the disciplinary tools a data format called CPACS (Common Parameterized Aircraft Configuration Schema) has been established [2, 3]. In a gradient free optimization process the modelling and sizing of the fuselage structure is performed using the PANDORA (Parametric Numerical Design and Optimization Routines for Aircraft) software framework. The PANDORA development started in 2016 to replace a set of established individual tools for model generation and structural sizing [4, 5] with the objectives to increase flexibility and performance. One major decision was to use the interpreted high level programming language Python and further open source packages such a numpy, pandas, etc. to allow the application on a variety of computer systems from Windows PCs up to computer clusters. In addition, a VTK based graphical user interface has been added to make the model preparation and results evaluation independent from third party commercial software [6,7]. Recently the structural analysis and sizing process has been adapted to integrate the FE Solver B2000++ [8]. This solver was initially developed at SMR in Switzerland and is now available at the DLR including the source code for future developments and direct integration into High-Fidelity process chains. In a first part of the paper recent developments of the PANDORA framework are presented after a brief overview of the MDO process chain and the CPACS data structure. These new developments include improvements in the model generation and the subsequent integration of structural analysis and sizing into the multi-disciplinary process chain. In this process the structural analyses can be performed using the established proprietary structural solvers ANSYS or NASTRAN. The validity of the results is proved by comparison with the previously used tools and the increase of performance is presented. The second part of the paper focusses on the integration of the FE solver B2000++ into the process chain, which shall allow a further reduction of the global process runtime by starting several calculations in parallel without any software license restrictions. A set of benchmark simulations with B2000++ are performed and the results on basic element, coupon and component level compared with those obtained with proprietary solvers. Finally, the integration into the MDO framework and first simulations on full aircraft level are presented. The comparison within the MDO process will include accuracy and performance aspects

High-Fidelity-based MDO: A Closer Look at the Selected Sub-Processes Overall Aircraft Design Synthesis, Loads Analysis, and Structural Optimization

Within the DLR project VicToria various high fidelity-based MDO processes were set-up as applicalble methods for aircraft design. Apart from aerodynamic optimization using high fidelity-based CFD analysis, the sub-processes overall aircraft design synthesis, loads analysis, and structural optimization were part of the MDO processes. The presented paper expounds such MDO sub-processes in order to exhibit their contributions and capabilities for the respected MDO process

Short-term functional adaptation of aquaporin-1 surface expression in the proximal tubule, a component of glomerulotubular balance

Transepithelial water flow across the renal proximal tubule is mediated predominantly by aquaporin-1 (AQP1). Along this nephron segment, luminal delivery and transepithelial reabsorption are directly coupled, a phenomenon called glomerulotubular balance. We hypothesized that the surface expression of AQP1 is regulated by fluid shear stress, contributing to this effect. Consistent with this finding, we found that the abundance of AQP1 in brush border apical and basolateral membranes was augmented >2-fold by increasing luminal perfusion rates in isolated, microperfused proximal tubules for 15 minutes. Mouse kidneys with diminished endocytosis caused by a conditional deletion of megalin or the chloride channel ClC-5 had constitutively enhanced AQP1 abundance in the proximal tubule brush border membrane. In AQP1-transfected, cultured proximal tubule cells, fluid shear stress or the addition of cyclic nucleotides enhanced AQP1 surface expression and concomitantly diminished its ubiquitination. These effects were also associated with an elevated osmotic water permeability. In sum, we have shown that luminal surface expression of AQP1 in the proximal tubule brush border membrane is regulated in response to flow. Cellular trafficking, endocytosis, an intact endosomal compartment, and controlled protein stability are the likely prerequisites for AQP1 activation by enhanced tubular fluid shear stress, serving to maintain glomerulotubular balance

Aerosols Transmit Prions to Immunocompetent and Immunodeficient Mice

Prions, the agents causing transmissible spongiform encephalopathies, colonize the brain of hosts after oral, parenteral, intralingual, or even transdermal uptake. However, prions are not generally considered to be airborne. Here we report that inbred and crossbred wild-type mice, as well as tga20 transgenic mice overexpressing PrPC, efficiently develop scrapie upon exposure to aerosolized prions. NSE-PrP transgenic mice, which express PrPC selectively in neurons, were also susceptible to airborne prions. Aerogenic infection occurred also in mice lacking B- and T-lymphocytes, NK-cells, follicular dendritic cells or complement components. Brains of diseased mice contained PrPSc and transmitted scrapie when inoculated into further mice. We conclude that aerogenic exposure to prions is very efficacious and can lead to direct invasion of neural pathways without an obligatory replicative phase in lymphoid organs. This previously unappreciated risk for airborne prion transmission may warrant re-thinking on prion biosafety guidelines in research and diagnostic laboratories

A thermostable messenger RNA based vaccine against rabies.

Although effective rabies virus vaccines have been existing for decades, each year, rabies virus infections still cause around 50.000 fatalities worldwide. Most of these cases occur in developing countries, where these vaccines are not available. The reasons for this are the prohibitive high costs of cell culture or egg grown rabies virus vaccines and the lack of a functional cold chain in many regions in which rabies virus is endemic. Here, we describe the excellent temperature resistance of a non-replicating mRNA based rabies virus vaccine encoding the rabies virus glycoprotein (RABV-G). Prolonged storage of the vaccine from -80°C to up to +70°C for several months did not impact the protective capacity of the mRNA vaccine. Efficacy after storage was demonstrated by the induction of rabies specific virus neutralizing antibodies and protection in mice against lethal rabies infection. Moreover, storing the vaccine at oscillating temperatures between +4° and +56°C for 20 cycles in order to simulate interruptions of the cold chain during vaccine transport, did not affect the vaccine's immunogenicity and protective characteristics, indicating that maintenance of a cold chain is not essential for this vaccine