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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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Parametric analysis of microwave and laser systems for communication and tracking with emphasis on aspects of operational environment and system implementation
Definition and implementation of simple LR/k/ context free grammars
Evaluation of corrective actions and hardware implementation for lunar module based on Apollo 13 flight incident
High level computer programming language /SAMPLE/ and parallel processing system to implement it
GCF high-speed data system design and implementation for 1971-1972, including doubled data transmission, block demultiplexing, and positive labeling of error-free blocks
NASA modular aerospace computer for attitude control high speed computation, describing implementation with LSI functional characters
Delta booster second stage packaged attitude control three-axis system, discussing electronic implementation for gyroscopic action control
The standard hydromechanical control system of a turbojet engine was replaced with a digital control system that implemented the same control laws. A detailed discussion of the digital control system in use with the engine is presented. The engine was operated in a sea-level test stand. The effects of control update interval are defined, and a method for extending this interval by using digital compensation is discussed.
Polak-Ribiere conjugate gradient algorithm modifications to eliminate minimization at each iteration for efficient implementation with convergence
The control of merging aircraft is formulated as a finite-time, quadratic optimal control problem of a linear system with state and control constraints. The purpose of this paper is to demonstrate that the Hybrid Air Traffic Controller (HAC), which has been previously developed as a solution to this problem, may be easily implemented. Use is made of both the properties of the algebraic solution to the matrix Riccati equation and the structure of the linear model. This approach results in a real-time synthesis procedure for the HAC which does not rely on iterative numerical integration techniques.
An analysis of V/STOL aircraft implementation and utilization is presented. The subjects discussed are: (1) short haul air transportation requirements, (2) available aircraft technology, (3) aircraft production requirements, (4) airport requirements, (5) roles and responsibilities, and (6) cost and funding.
The requirements for the safety training program are reported for KSC including transportation, inspection, checkout operations, maintenance of launch vehicles, spacecraft, ground support equipment, and launch teams. The responsibilities and mechanics for implementing the program are outlined.
The Mariner Mars 1971 mission which was another step in the continuing program of planetary exploration in search of evidence of exobiological activity, information on the origin and evolution of the solar system, and basic science data related to the study of planetary physics, geology, planetology, and cosmology is reported. The mission plan was designed for two spacecraft, each performing a separate but complementary mission. However, a single mission plan was actually used for Mariner 9 because of failure of the launch vehicle for the first spacecraft. The implementation is described, of the Mission Operations System, including organization, training, and data processing development and operations, and Mariner 9 spacecraft cruise and orbital operations through completion of the standard mission from launch to solar occultation in April 1972 are discussed.
The simulation of an adaptive ground implemented phased array of five antenna elements is reported for a very high frequency system design that is tolerant to the radio frequency interference environment encountered by a tracking data relay satellite. Signals originating from satellites are received by the VHF ring array and both horizontal and vertical polarizations from each of the five elements are multiplexed and transmitted down to ground station. A panel on the transmitting end of the simulation chamber contains up to 10 S-band RFI sources along with the desired signal to simulate the dynamic relationship between user and TDRS. The 10 input channels are summed, and desired and interference signals are separated and corrected until the resultant sum signal-to-interference ratio is maximized. Testing performed with this simulation equipment demonstrates good correlation between predicted and actual results.
The operation specifications for the NASA Aerospace Safety Information System are presented. The environment which leads to the design, implementation, and installation of the system is described. The manner in which the various components of the system inter-relate is explained. The manner in which the system was installed and subsequently modified is reported.
Tests were conducted to determine the feasibility of using an adaptive ground implemented phased array (AGIPA) to overcome the limitations of the radio frequency interference limited low data Tracking and Data Relay Satellite VHF return link. A feasibility demonstration model of a single user channel AFIPA system was designed, developed, fabricated, and evaluated. By scaling the frequency and aperture geometry from VHF to S-band, the system performance was more easily demonstrated in the controlled environment of an anechoic chamber. The testing procedure employs an AGIPA in which received signals from each element of the array are processed on the ground to form an adaptive, independent, computer controlled beam for each user.
The implementation of the NASTRAN system on the CDC CYBER 74 SCOPE 3.4 Operating System is described. The flexibility of the NASTRAN system made it possible to accomplish the change with no major problems. Various sizes of benchmark and test problems, ranging from two hours to less than one minute CP time were run on the CDC CYBER SCOPE 3.3, Univac EXEC-8, and CDC CYBER SCOPE 3.4. The NASTRAN installation deck is provided.
The derivation of an approximate error characteristic equation describing the transient system error response is given, along with a procedure for selecting adaptive gain parameters so as to relate to the transient error response. A detailed example of the application and implementation of these methods for a space shuttle type vehicle is included. An extension of the characteristic equation technique is used to provide an estimate of the magnitude of the maximum system error and an estimate of the time of occurrence of this maximum after a plant parameter disturbance. Techniques for relaxing certain stability requirements and the conditions under which this can be done and still guarantee asymptotic stability of the system error are discussed. Such conditions are possible because the Lyapunov methods used in the stability derivation allow for overconstraining a problem in the process of insuring stability.