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  • Aircraft Design, Testing and Performance  (5)
  • switched linear system
  • 2000-2004  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Controllability of a class of hybrid dynamic systems (III)—Multiple time-delay case (2003)
    Springer
    Applied mathematics and mechanics 24 (2003), S. 1063-1074 
    Details
    ISSN: 1573-2754
    Keywords: hybrid dynamic system ; switched linear system ; time-delay ; controllability ; controllable set ; switching sequence ; switching path ; TP13 ; TP273 ; O317 ; 93B05 ; 93B27 ; 93C99
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract The controllability for switched linear systems with time-delay in controls is first investigated. The whole work contains three parts. This is the third part. The definition and determination of controllability of switched linear systems with multiple time-delay in control functions is mainly investigated. The sufficient and necessary conditions for the one-periodic, multiple-periodic controllability of periodic-type systems and controllability of aperiodic systems are presented, respectively. Finally, the case of distinct delays is discussed, it is shown that the controllability is independent of the size of delays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02437638
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Controllability of a class of hybrid dynamic systems (II)—Single time-delay case (2003)
    Springer
    Applied mathematics and mechanics 24 (2003), S. 1051-1062 
    Details
    ISSN: 1573-2754
    Keywords: hybrid dynamic system ; switched linear system ; time-delay ; controllability ; controllable set ; switching sequence ; switching path ; TP13 ; TP273 ; O317 ; 93B05 ; 93B27 ; 93C99
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract The controllability for switched linear systems with time-delay in controls is first investigated. The whole work contains three parts. This is the second part. The definition and determination of controllability of switched linear systems with single time-delay in control functions is mainly investigated. The sufficient and necessary conditions for the oneperiodic, multiple-periodic controllability of periodic-type systems and controllability of periodic systems are presented, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02437637
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Controllability of a class of hybrid dynamic systems (I)—Basic properties and preliminary results (2003)
    Springer
    Applied mathematics and mechanics 24 (2003), S. 1041-1050 
    Details
    ISSN: 1573-2754
    Keywords: hybrid dynamic system ; switched linear system ; time-delay ; controllability ; generalized cyclic invariant subspace ; switching sequence ; switching path ; TP13 ; TP273 ; O317 ; 93B05 ; 93B27 ; 93C99
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract The controllability for switched linear system with time-delay in controls was first investigated. The whole work contains three parts. This is the first part, including problem formulation and some preliminaries. Firstly, the mathematical model of switched linear systems with time-delay in control functions was presented. Secondly, the concept of column space, cyclic invariant subspace and generalized cyclic invariant subspace were introduced. And some basic properties, such as separation lemma, were presented. Finally, a basic lemma was given to reveal the relation between the solution set of a centain integral equations and the generalized cyclic invariant subspace. This lemma will play an important role in the determination of controllability. All these definitions and lemmas are necessary research tools for controllability analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02437636
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    Paper (German National Licenses)
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  • 4
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    Evaluation of the National Throughput Benefits of the Civil Tilt Rotor (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The air transportation system is a key part of the U.S. and global economic infrastructure. In recent years, this system, by any measure of usage - operations, enplanements, or revenue passenger miles (RPMs) - has grown rapidly. The rapid growth in demand has not been matched; however, by commensurate increases in the ability of airports and the airspace system to handle the additional traffic. As a result, the air transportation system is approaching capacity and airlines will face excessive delays or significant constraints on service unless capacity is expanded. To expand capacity, the air traffic management system must be improved. To improve the air traffic management system, the National Aeronautics and Space Administration (NASA) Aerospace Technology Enterprise developed the strategic goal of tripling air traffic throughput over the next 10 years, in all weather conditions, while at least maintaining current safety standards. As the first step in meeting that goal, the NASA Intercenter Systems Analysis Team (ISAT) is evaluating the contribution of existing programs to meet that goal. A major part of the study is an examination of the ability of the National Airspace System (NAS) to meet the predicted growth in travel demand and the potential benefits of technology infusion to expand NAS capacity. We previously analyzed the effects of the addition of two technology elements - Terminal Area Productivity (TAP) and Advanced Air Transportation Technologies (AATT). The next program we must analyze is not specific to airspace or aircraft technology. The program incorporates a fundamentally different vehicle to improve throughput: the civil tilt rotor (CTR). The CTR has the unique operating characteristic of being able to take off and land like a rotorcraft (vertical take off and landing, or VTOL, capability) but cruises like a traditional fixed-wing aircraft. The CTR also can operate in a short take off and landing (STOL) mode; generally, with a greater payload capacity (i.e., more passengers) than when operating in the VTOL mode. CTR could expand access to major airports without interfering with fixed-wing aircraft operating on congested runways and it could add service to new markets without the infrastructure support needed for fixed-wing aircraft. During FY 1999, we preliminarily assessed the feasibility of operating CTRs at two major U.S. airports as part of the annual review of NASA aerospace goals by the ISAT. This current study expands the analysis and concepts of that study to the complete NAS to quantify the national throughput effects of the CTR.
    Keywords: Aircraft Design, Testing and Performance
    Type: NASA/CR-2001-211055 , NAS 1.26:211055 , LMI-NS003S1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    A Small Aircraft Transportation System (SATS) Demand Model (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The Small Aircraft Transportation System (SATS) demand modeling is a tool that will be useful for decision-makers to analyze SATS demands in both airport and airspace. We constructed a series of models following the general top-down, modular principles in systems engineering. There are three principal models, SATS Airport Demand Model (SATS-ADM), SATS Flight Demand Model (SATS-FDM), and LMINET-SATS. SATS-ADM models SATS operations, by aircraft type, from the forecasts in fleet, configuration and performance, utilization, and traffic mixture. Given the SATS airport operations such as the ones generated by SATS-ADM, SATS-FDM constructs the SATS origin and destination (O&D) traffic flow based on the solution of the gravity model, from which it then generates SATS flights using the Monte Carlo simulation based on the departure time-of-day profile. LMINET-SATS, an extension of LMINET, models SATS demands at airspace and airport by all aircraft operations in US The models use parameters to provide the user with flexibility and ease of use to generate SATS demand for different scenarios. Several case studies are included to illustrate the use of the models, which are useful to identify the need for a new air traffic management system to cope with SATS.
    Keywords: Aircraft Design, Testing and Performance
    Type: NASA/CR-2001-210874 , NAS 1.26:210874 , LMI-NS004S1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Main Chamber Injectors for Advanced Hydrocarbon Booster Engines (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Achieving the highest possible specific impulse has long been a key driver for space launch systems. Recently, more importance has been placed on the need for increased reliability and streamlined launch operations. These general factors along with more specific mission requirements have provided a new focus that is centered on the oxidizer rich staged combustion (ORSC) cycle. Despite a history of use in Russia that extends back to the 1960's, a proven design methodology for ORSC cycle engines does not exist in the West. This lack of design expertise extends to the main chamber injector, a critical subcomponent that largely determines the engine performance and main chamber life. The goals of the effort described here are to establish an empirical knowledge base to provide a fundamental understanding of main chamber injectors and for verification of an injector design methodology for the ORSC cycle. The design of a baseline injector element, derived from information on Russian engines in the open literature, is presented. The baseline injector comprises a gaseous oxidizer core flow and an annular swirling fuel flow. Sets of equations describing the steady-state and the dynamic characteristics of the injector are presented; these equations, which form the basis of the design analysis methodology, will be verified in tests later this year. On-going cold flow studies, using nitrogen and water as simulants, are described which indicate highly atomized and symmetric sprays.
    Keywords: Aircraft Design, Testing and Performance
    Type: AIAA Paper 2003-4599 , 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit; Jul 20, 2003 - Jul 23, 2003; Huntsville, AL; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    A Small-Scale Tiltrotor Model Operating in Descending Flight (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: As a rotor s descent velocity in low speed flight approaches the induced wake velocity, a vortex ring is formed around the circumference of the rotor disk causing the flow to become very unsteady. This condition is known as Vortex Ring State (VRS). The aerodynamic Characteristics of edgewise operating rotors in this VRS induced environment have been studied for many years. In the 1960 s, two propellers were tested in vertical or near vertical descent, indicating a loss in thrust in the region of VRS. Thrust fluctuations of both single and tandem rotor configurations while operating in VRS were reported. More recently, the effects of descending flight on a single rotor operating in close proximity to a physical image plane, simulating the effects of a twin rotor tiltrotor system were investigated. Mean rotor thrust reductions and thrust fluctuations were shown in VRS. Results indicated the need to acquire additional data with a two-rotor model and the need to investigate the use of a single rotor/image plane apparatus to identify the characteristics of a two-rotor flowfield. As a result a small-scale tiltrotor model with 2-b1adedy untwisted, teetering rotors was tested at various states of descent and sideslip. Dual-rotor, single-rotor with image plane, and isolated-rotor results were reported, suggesting the single-rotor with image plane configuration may not properly capture the aerodynamic nature of a dual-rotor vehicle. Recommendations included additional testing of a model that better represents the physical characteristics of a tiltrotor aircraft. Specific recommendations for model improvements included using three-bladed rotors, twisted blades, a tiltrotor fuselage and wings.
    Keywords: Aircraft Design, Testing and Performance
    Type: 28th European Rotorcraft Forum; Sep 17, 2002 - Sep 20, 2002; Bristol; United Kingdom
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Integrating LMINET with TAAM and SIMMOD: A Feasibility Study (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: LMINET is a queuing network air traffic simulation model implemented at 64 large airports and the entire National Airspace System in the United States. TAAM and SIMMOD are two widely used air traffic event-driven simulation models mostly for airports. Based on our proposed Progressive Augmented window approach, TAAM and SIMMOD are integrated with LMINET though flight schedules. In the integration, the flight schedules are modified through the flight delays reported by the other models. The benefit to the local simulation study is to let TAAM or SIMMOD take the modified schedule from LMINET, which takes into account of the air traffic congestion and flight delays at the national network level. We demonstrate the value of the integrated models by the case studies at Chicago O'Hare International Airport and Washington Dulles International Airport. Details of the integration are reported and future work for a full-blown integration is identified.
    Keywords: Aircraft Design, Testing and Performance
    Type: NASA/CR-2001-210875 , NAS 1.26:210875 , LMI-NS008S1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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