L2-stability and L2-instability of linear time-invariant distributed feedback systems perturbed by a small delay in the loop.
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Barman, J. F.↗
SEARCH · Engineering Papers
Results for “distributed system”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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MSFC Skylab Orbital Workshop, volume 2
The design and development of the Skylab Orbital Workshop are discussed. The subjects considered are: (1) thrust attitude control system, (2) solar array system, (3) electrical power distribution system, (4) communication and data acquisition system, (5) illumination system, and (6) caution and warning system.
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Historical review of C-5A lift distribution control systems
Analytical and experimental development work on various load alleviation systems for the C-5A is reviewed to trace the development of the technical and hardware concepts to the present time. Variations in system objectives, means of implementation and effects on loads and airplane performance, stability and control are discussed.
Disney, T. E.↗
The C-5A active lift distribution control system
The ALDCS development and design tasks, ALDCS functional configuration, and resulting challenges encountered while accomplishing the first phase of the program are described. These tasks are establishing system requirements and criteria and synthesizing a system mechanization to meet the desired load alleviation, stability margins, flight safety, and flying qualities performance. Results of the ALDCS development and prototype system flight simulation programs, and control law optimization including system stability, handling qualities and structural load analyses are presented, along with concluding remarks relative to the system design integration.
Hargrove, W. J.↗
Feedback control of two beam, two joint systems with distributed flexibility
The control of the flexible motion in a plane of two pinned beams is addressed with application to remote manipulators. Three types of linear feedback control schemes are considered: joint angle and velocity feedback with (GRC) and without (IJC) cross joint feedback, and feedback of flexible state variables (FFC). Two models of the distributed flexibility are presented along with some results obtained from them. The relative merit of the three control schemes is discussed.
Book, W. J.↗
SPS Energy Conversion Power Management Workshop
Energy technology concerning photovoltaic conversion, solar thermal conversion systems, and electrical power distribution processing is discussed. The manufacturing processes involving solar cells and solar array production are summarized. Resource issues concerning gallium arsenides and silicon alternatives are reported. Collector structures for solar construction are described and estimates in their service life, failure rates, and capabilities are presented. Theories of advanced thermal power cycles are summarized. Power distribution system configurations and processing components are presented.
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The reduced order model problem in distributed parameter systems adaptive identification and control
The basic assumption that a large space structure can be decoupled preceding the application of reduced order active control was considered and alternative solutions to the control of such structures (in contrast to the strict modal control) were investigated. The transfer function matrix from the actuators to the sensors was deemed to be a reasonable candidate. More refined models from multivariable systems theory were studied and recent results in the multivariable control field were compared with respect to theoretical deficiencies and likely problems in application to large space structures.
Johnson, C. R., Jr.↗
Filtering and smoothing for linear discrete-time distributed parameter systems based on Wiener-Hopf theory with application to estimation of air pollution
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Omatu, S.↗
Estimation of distributed parameter systems
The estimation and control of large flexible space structures pose significant new control technology problems. One major problem area is the closed-loop stability of a structure that has been modeled with truncated modal dynamics. Stability problems arise due to the control design process beginning with a deficient model. This work provides the necessary conditions for the optimal estimation of infinite dimensional (partial-differential equation) systems. This approach can be particularly useful for initial control studies and for gaining considerable insight into what the optimal estimator for a truly infinite dimensional system should be. A detailed example of the estimation of the continuous shape of a string in tension is presented.
Schaechter, D. B.↗
Distributed photovoltaic systems: Utility interface issues and their present status. Intermediate/three-phase systems
The interface issues between the intermediate-size Power Conditioning Subsystem (PCS) and the utility are considered. A literature review yielded facts about the status of identified issues.
Das, R. L.↗
Database interfaces on NASA's heterogeneous distributed database system
The purpose of the ORACLE interface is to enable the DAVID program to submit queries and transactions to databases running under the ORACLE DBMS. The interface package is made up of several modules. The progress of these modules is described below. The two approaches used in implementing the interface are also discussed. Detailed discussion of the design of the templates is shown and concluding remarks are presented.
Huang, S. H. S.↗
On compactness of admissible parameter sets: Convergence and stability in inverse problems for distributed parameter systems
A series of numerical examples is reported and several algorithms compared for estimation of coefficients in differential equation models. Unconstrained, constrained and Tikhonov regularization methods are tested for their behavior with regard to both convergence (of approximation methods for the states and parameters) and stability (continuity of the estimates with respect to perturbations in the data or observed states).
Banks, H. T.↗
Design derivatives of eigenvalues and eigenfunctions for self-adjoint distributed parameter systems
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Reiss, R.↗
A support architecture for reliable distributed computing systems
The Clouds kernel design was through several design phases and is nearly complete. The object manager, the process manager, the storage manager, the communications manager, and the actions manager are examined.
Mckendry, Martin S.↗
National Space Transportation System telemetry distribution and processing, NASA-JFK Space Center/Cape Canaveral
Prelaunch, launch, mission, and landing distribution of RF and hardline uplink/downlink information between Space Shuttle Orbiter/cargo elements, tracking antennas, and control centers at JSC, KSC, MSFC, GSFC, ESMC/RCC, and Sunnyvale are presented as functional block diagrams. Typical mismatch problems encountered during spacecraft-to-project control center telemetry transmissions are listed along with new items for future support enhancement.
Jenkins, George↗
Estimation on nonlinear damping in second order distributed parameter systems
An approximation and convergence theory for the identification of nonlinear damping in abstract wave equations is developed. It is assumed that the unknown dissipation mechanism to be identified can be described by a maximal monotone operator acting on the generalized velocity. The stiffness is assumed to be linear and symmetric. Functional analytic techniques are used to establish that solutions to a sequence of finite dimensional (Galerkin) approximating identification problems in some sense approximate a solution to the original infinite dimensional inverse problem.
Banks, H. T.↗
Database interfaces on NASA's heterogeneous distributed database system
The syntax and semantics of all commands used in the template are described. Template builders should consult this document for proper commands in the template. Previous documents (Semiannual reports) described other aspects of this project. Appendix 1 contains all substituting commands used in the system. Appendix 2 includes all repeating commands. Appendix 3 is a collection of DEFINE templates from eight different DBMS's.
Huang, Shou-Hsuan Stephen↗
On the continuous dependence with respect to sampling of the linear quadratic regulator problem for distributed parameter systems
The convergence of solutions to the discrete or sampled time linear quadratic regulator problem and associated Riccati equation for infinite dimensional systems to the solutions to the corresponding continuous time problem and equation, as the length of the sampling interval (the sampling rate) tends toward zero (infinity) is established. Both the finite and infinite time horizon problems are studied. In the finite time horizon case, strong continuity of the operators which define the control system and performance index together with a stability and consistency condition on the sampling scheme are required. For the infinite time horizon problem, in addition, the sampled systems must be stabilizable and detectable, uniformly with respect to the sampling rate. Classes of systems for which this condition can be verified are discussed. Results of numerical studies involving the control of a heat/diffusion equation, a hereditary of delay system, and a flexible beam are presented and discussed.
Rosen, I. G.↗