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New Approaches for the Use of Extended Mock-ups for the Development of Air Traffic Controller Working Positions
Full text linkToday, integrating new functions into air traffic controller working positions or developing completely new displays are time-consuming and expensive processes. The users are often only included during the concept phase and after the main development phase is completed. Therefore, they do not have the chance to influence the design and development process by giving structural feedback. Any subsequent changes to the system after completing the main development phase will be expensive and slow. This paper proposes a new approach to integrate designers and users more tightly in the development process for digital air traffic control systems. By creating and reviewing realistic mock-ups in small iterative steps, the look and feel of future support functions can be validated in advance of the actual implementation and easily adapted if changes are requested. We performed a series of steps to evaluate the new workflow as a case study, including idea development, design, validation, and implementation into the target system. In a validation campaign with air traffic controllers, the developed design and functionalities received very positive feedback and the new workflow was successfully applied and evaluated as a case study
Concolic Execution of Multi-threaded Assembly Programs
No full textAt its core, this thesis is an exploratory study that attempts to determine whether a relatively new technique, concolic execution for multi-threaded programs [12], can be used in a particular context, assembly lifting. It presents a prototype for an ARM v7 assembly
lifter using this technique. The thesis contains a detailed description of how concolic execution for multi-threaded programs works and also covers many optimizations (both implemented and unimplemented) to improve the scalability of this technique. The work considers mainly embedded software for safety-critical applications, e.g., space applications. Due to the prototypical nature of the assembly lifter, some important features are not yet covered. At the moment, the tool only creates an internal representation of the program and does not translate this representation into the intended target language, LLVM-IR. It also covers only a small subset of the assembly language and does not cover some important features of the assembly language (interrupts, proper initialization of certain global variables, …). The scalability and applicability of the proposed solution is evaluated on synthetic test cases. At the moment, the scalability of the tool is not sufficient to be able to apply it to large assembly programs
Development of Short-Range Laminar Aircraft: Conceptual Design with Integrated System Sizing
No full textThe aviation industry is currently facing significant pressure to enhance its sustainability by increasing aircraft energy efficiency and reducing its climate impact. A promising approach to fulfilling these demands is to improve the aircraft's aerodynamic performance through drag reduction by implementing laminar flow technologies, particularly Natural Laminar Flow (NLF) or Hybrid Laminar Flow Control (HLFC). Prior works assessing laminar flow technologies have mostly focused on evaluating their aerodynamic performance and, in the case of the HLFC, on the influence of system design. The impact of these technologies on the overall aircraft performance has received only limited consideration, with the majority of studies focusing on long-range aircraft, utilizing simplified models for HLFC systems, and considering only one laminar flow technology at a time. This study adopts a holistic approach to assess the potential fuel savings that could be achieved by combined application of NLF and HLFC technologies on the various components of a short-to-medium range aircraft concept, with an intended entry into service in 2035. To achieve this objective, a conceptual aircraft design process is employed. This process captures the aerodynamic effects of laminar flow technologies and fully integrates the HLFC system design to provide an accurate estimate of aircraft performance. The findings of this study reveal a potential for fuel savings of 5.9% on the design mission through the combined application of NLF and HLFC, compared to a turbulent aircraft with an equivalent technology level. Additionally, the results indicate that strategic combination of the two technologies on a single component can significantly reduce complexity while further enhancing fuel savings. A failure analysis also provides an initial estimate of the impact of various failure scenarios on the aircraft's performance. These findings demonstrate that, despite the aircraft's short range, the combined implementation of the two laminar flow technologies offers a potential for fuel savings with reduced complexity, motivating further research in their application to this aircraft category
Laserantriebe
Full text linkEinführung in "Beamed Energy Propulsion": Funktionsprinzip des Lasers, Beispiele und Ausbreitung von Laserstrahlung. Überblick über Antriebskonzepte: Photon Propulsion, ablative Laserantriebe, Laser Lightcraft, Kollisionsvermeidung bei Weltraumschrott und Near-Earth Objects, Beseitigung von Weltraumschrott
Statistics of Received Power Time Series for Optical LEO Satellite Uplinks
No full textIn free-space optical satellite communications, a transmitted optical signal is perturbed by pointing inaccuracies and through the atmosphere's index-of-refraction turbulence. This leads to signal fluctuations and power fading when detected by a receiver. Knowledge of these signal instability statistics is advantageous for the design of robust ground- and space-based optical communication systems. For example, the development of optimized automatic repeat request (ARQ) and forward error correction (FEC) protocols to compensate these losses is facilitated. The channel characteristics of a ground-to-satellite (uplink) and satellite-to-ground (downlink) transmission change with the elevation angle of the link direction, and consequently, the signal fluctuations and power fading also vary. In this work, numerical time series of received power are generated for uplink scenarios to low Earth orbit (LEO) satellites for different satellite elevations. The time series are generated for two experimental scenarios, considering the effects of a gamma-gamma and lognormal-distributed atmospheric scintillation and the use of transmitter diversity. The generated series of power are compared with analytical results and measurements in terms of the run of statistical parameters, and the results are contrasted. The results can be used for link-budget design, for communications standardization, and for the analysis and design of fading mitigation techniques that prevent signal fading and data loss
A review of Reynolds-averaged Navier-Stokes modeling for hypersonic large cone-flares
No full textThis work assesses the status of Reynolds-averaged Navier-Stokes' (RANS) predictive capability for axi-symmetric hypersonic geometries. An in-depth literature review on the topic is provided including relevant developments in the field of RANS for these types of setups. Furthermore, as part of the Applied Vehicle Technology-352 on hypersonic turbulence, a code-to-code comparison on two large cone-flare geometries, experimentally studied at Calspan-University of Buffalo Research Center, has been performed to evaluate the variability in predictions for freestream Mach numbers ranging between 5 and 13 at low enthalpy conditions. The nature of the physics found in cone-flare geometries is known to be extremely challenging for RANS computational fluid dynamics codes, a fact that is confirmed in this work
INTENTAS - an entanglement-enhanced atomic sensor for microgravity
Full text linkThe INTENTAS project aims to develop an atomic sensor utilizing entangled Bose-Einstein condensates (BECs) in a microgravity environment. This key achievement is necessary to advance the capability for measurements that benefit from both entanglement-enhanced sensitivities and extended interrogation times. The project addresses significant challenges related to size, weight, and power management (SWaP) specific to the experimental platform at the Einstein-Elevator in Hannover. The design ensures a low-noise environment essential for the creation and detection of entanglement. Additionally, the apparatus features an innovative approach to the all-optical creation of BECs, providing a flexible system for various configurations and meeting the requirements for rapid turnaround times. Successful demonstration of this technology in the Einstein-Elevator will pave the way for a future deployment in space, where its potential applications will unlock high-precision quantum sensing
Extended Staring Spotlight - A New SAR Method of Acquisition via Concurrent Imaging
Full text linkWithin the field of Synthetic Aperture Radar (SAR), its use for acquiring detailed images on Earth's surface has always been constrained by a particular trade-off - the one between maximum obtainable area and finest possible resolution. Techniques such as ScanSAR can achieve wide swaths of land but degrading significantly image resolution, while other methods such as Staring Spotlight yield detailed images with extremely limited surface area. With the usage of a novel pulse emitting technique - Concurrent Imaging - this thesis proposed and proves the feasibility of the Extended Staring Spotlight (EST): a new acquisition mode which yields double the size of a conventional Staring Spotlight scene, while maintaining its high-level of detail throughout the image