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  • 1
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    Sustainability, Vol. 8, Pages 342: Sustainable Entrepreneurship in SMEs: A Business Performance Perspective (2016)
    MDPI Publishing
    Details
    Publication Date: 2016-04-08
    Description: Assuming that sustainable entrepreneurship leads to business performance, the present paper intends to investigate the standpoints of SMEs (small and medium-sized enterprises) entrepreneurs on different facets. The emphasis is laid on the entrepreneurs’ approaches towards people, planet and profit and on their prioritization within business dynamics. The aforementioned dimensions are deemed important factors engendering business performance in terms of turnover, customer attraction and retention and market share. With a view to testing the advanced hypotheses, we employed a quantitative perspective relying on a questionnaire-based survey. As the results posited, the proposed model accounts for almost 50 percent of variance in business performance, whereas sustainable entrepreneurship approaches towards the people and profit dimensions have a significant positive influence on business performance.
    Electronic ISSN: 2071-1050
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI Publishing
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  • 2
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    An anionic synthetic sugar containing 6-SO3-NAcGlc mimics the sulfated cruzipain epitope that plays a central role in immune recognition (2012)
    Wiley
    Details
    Publication Date: 2012-09-04
    Print ISSN: 1742-464X
    Electronic ISSN: 1742-4658
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Published by Wiley on behalf of Federation of European Biochemical Societies.
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  • 3
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    Biophysical Characterization of Covalently Modified Protein Tau: Oligomers, Aggregation, and Tubulin Interactions (2020)
    Cell Press
    Details
    Publication Date: 2020-02-01
    Print ISSN: 0006-3495
    Electronic ISSN: 1542-0086
    Topics: Biology , Physics
    Published by Cell Press
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  • 4
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    Towards Intelligent Control for Next Generation Aircraft (2008)
    In:  Other Sources
    Details
    Publication Date: 2019-07-19
    Description: NASA Aeronautics Subsonic Fixed Wing Project is focused on mitigating the environmental and operation impacts expected as aviation operations triple by 2025. The approach is to extend technological capabilities and explore novel civil transport configurations that reduce noise, emissions, fuel consumption and field length. Two Next Generation (NextGen) aircraft have been identified to meet the Subsonic Fixed Wing Project goals - these are the Hybrid Wing-Body (HWB) and Cruise Efficient Short Take-Off and Landing (CESTOL) aircraft. The technologies and concepts developed for these aircraft complicate the vehicle s design and operation. In this paper, flight control challenges for NextGen aircraft are described. The objective of this paper is to examine the potential of state-of-the-art control architectures and algorithms to meet the challenges and needed performance metrics for NextGen flight control. A broad range of conventional and intelligent control approaches are considered, including dynamic inversion control, integrated flight-propulsion control, control allocation, adaptive dynamic inversion control, data-based predictive control and reinforcement learning control.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN121 , International Powered Lift Conference; Jul 22, 2008 - Jul 24, 2008; London; United Kingdom
    Format: text
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  • 5
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    Robust Maneuvering Envelope Estimation Based on Reachability Analysis in an Optimal Control Formulation (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper discusses an algorithm for estimating the safe maneuvering envelope of damaged aircraft. The algorithm performs a robust reachability analysis through an optimal control formulation while making use of time scale separation and taking into account uncertainties in the aerodynamic derivatives. Starting with an optimal control formulation, the optimization problem can be rewritten as a Hamilton- Jacobi-Bellman equation. This equation can be solved by level set methods. This approach has been applied on an aircraft example involving structural airframe damage. Monte Carlo validation tests have confirmed that this approach is successful in estimating the safe maneuvering envelope for damaged aircraft.
    Keywords: Aircraft Stability and Control; Air Transportation and Safety
    Type: ARC-E-DAA-TN11112 , International Conference on Control and Fault-Tolerant Systems (SysTol''13); Oct 09, 2013 - Oct 11, 2013; Nice; France
    Format: application/pdf
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  • 6
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    Next Generation Civil Transport Aircraft Design Considerations for Improving Vehicle and System-Level Efficiency (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The future of aviation will benefit from research in aircraft design and air transportation management aimed at improving efficiency and reducing environmental impacts. This paper presents civil transport aircraft design trends and opportunities for improving vehicle and system-level efficiency. Aircraft design concepts and the emerging technologies critical to reducing thrust specific fuel consumption, reducing weight, and increasing lift to drag ratio currently being developed by NASA are discussed. Advancements in the air transportation system aimed towards system-level efficiency are discussed as well. Finally, the paper describes the relationship between the air transportation system, aircraft, and efficiency. This relationship is characterized by operational constraints imposed by the air transportation system that influence aircraft design, and operational capabilities inherent to an aircraft design that impact the air transportation system.
    Keywords: Air Transportation and Safety; Aircraft Design, Testing and Performance
    Type: ARC-E-DAA-TN10383 , Aviation Technology, Integration, and Operations (ATIO) Conference; Aug 12, 2013 - Aug 14, 2013; Los Angeles, CA; United States
    Format: application/pdf
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  • 7
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    Motion-Based Piloted Simulation Evaluation of a Control Allocation Technique to Recover from Pilot Induced Oscillations (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper describes the maturation of a control allocation technique designed to assist pilots in the recovery from pilot induced oscillations (PIOs). The Control Allocation technique to recover from Pilot Induced Oscillations (CAPIO) is designed to enable next generation high efficiency aircraft designs. Energy efficient next generation aircraft require feedback control strategies that will enable lowering the actuator rate limit requirements for optimal airframe design. One of the common issues flying with actuator rate limits is PIOs caused by the phase lag between the pilot inputs and control surface response. CAPIO utilizes real-time optimization for control allocation to eliminate phase lag in the system caused by control surface rate limiting. System impacts of the control allocator were assessed through a piloted simulation evaluation of a non-linear aircraft simulation in the NASA Ames Vertical Motion Simulator. Results indicate that CAPIO helps reduce oscillatory behavior, including the severity and duration of PIOs, introduced by control surface rate limiting.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN10070 , AIAA Guidance, Navigation, and Control Conference; Aug 19, 2013 - Aug 22, 2013; Boston, MA; United States
    Format: application/pdf
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  • 8
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    Safe Maneuvering Envelope Estimation Based on a Physical Approach (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper discusses a computationally efficient algorithm for estimating the safe maneuvering envelope of damaged aircraft. The algorithm performs a robust reachability analysis through an optimal control formulation while making use of time scale separation and taking into account uncertainties in the aerodynamic derivatives. This approach differs from others since it is physically inspired. This more transparent approach allows interpreting data in each step, and it is assumed that these physical models based upon flight dynamics theory will therefore facilitate certification for future real life applications.
    Keywords: Air Transportation and Safety; Aircraft Stability and Control
    Type: ARC-E-DAA-TN10295 , AIAA Guidance, Navigation, and Control Conference 2013; Aug 18, 2013 - Aug 22, 2013; Boston, MA; United States
    Format: application/pdf
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  • 9
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    Piloted Simulator Evaluation of Maneuvering Envelope Information for Flight Crew Awareness (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The implementation and evaluation of an efficient method for estimating safe aircraft maneuvering envelopes are discussed. A Bayesian approach is used to produce a deterministic algorithm for estimating aerodynamic system parameters from existing noisy sensor measurements, which are then used to estimate the trim envelope through efficient high- fidelity model-based computations of attainable equilibrium sets. The safe maneuverability limitations are extended beyond the trim envelope through a robust reachability analysis derived from an optimal control formulation. The trim and maneuvering envelope limits are then conveyed to pilots through three axes on the primary flight display. To evaluate the new display features, commercial airline crews flew multiple challenging approach and landing scenarios in the full motion Advanced Concepts Flight Simulator at NASA Ames Research Center, as part of a larger research initiative to investigate the impact on the energy state awareness of the crew. Results show that the additional display features have the potential to significantly improve situational awareness of the flight crew.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN19341 , AIAA Infotech 2015; Jan 05, 2015 - Jan 09, 2015; Kissimmee, FL; United States
    Format: application/pdf
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  • 10
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    Sensitivity Analysis of Linear Programming and Quadratic Programming Algorithms for Control Allocation (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Next Generation (NextGen) transport aircraft configurations being investigated as part of the NASA Aeronautics Subsonic Fixed Wing Project have more control surfaces, or control effectors, than existing transport aircraft configurations. Conventional flight control is achieved through two symmetric elevators, two antisymmetric ailerons, and a rudder. The five effectors, reduced to three command variables, produce moments along the three main axes of the aircraft and enable the pilot to control the attitude and flight path of the aircraft. The NextGen aircraft will have additional redundant control effectors to control the three moments, creating a situation where the aircraft is over-actuated and where a simple relationship does not exist anymore between the required effector deflections and the desired moments. NextGen flight controllers will incorporate control allocation algorithms to determine the optimal effector commands and attain the desired moments, taking into account the effector limits. Approaches to solving the problem using linear programming and quadratic programming algorithms have been proposed and tested. It is of great interest to understand their relative advantages and disadvantages and how design parameters may affect their properties. In this paper, we investigate the sensitivity of the effector commands with respect to the desired moments and show on some examples that the solutions provided using the l2 norm of quadratic programming are less sensitive than those using the l1 norm of linear programming.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN-369 , AIAA Infotech@Aerospace Conference and Exhibit; Apr 06, 2009 - Apr 09, 2009; Seattle, WA; United States
    Format: application/pdf
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