Standard interface definition for avionics data bus systems

Data bus for avionics system of space shuttle, noting functions of interface unit, error detection and recovery, redundancy, and bus control philosoph

Advanced flight control system study

The architecture, requirements, and system elements of an ultrareliable, advanced flight control system are described. The basic criteria are functional reliability of 10 to the minus 10 power/hour of flight and only 6 month scheduled maintenance. A distributed system architecture is described, including a multiplexed communication system, reliable bus controller, the use of skewed sensor arrays, and actuator interfaces. Test bed and flight evaluation program are proposed

Advanced Software Techniques for Data Management Systems. Volume 2: Space Shuttle Flight Executive System: Functional Design

A functional design of software executive system for the space shuttle avionics computer is presented. Three primary functions of the executive are emphasized in the design: task management, I/O management, and configuration management. The executive system organization is based on the applications software and configuration requirements established during the Phase B definition of the Space Shuttle program. Although the primary features of the executive system architecture were derived from Phase B requirements, it was specified for implementation with the IBM 4 Pi EP aerospace computer and is expected to be incorporated into a breadboard data management computer system at NASA Manned Spacecraft Center's Information system division. The executive system was structured for internal operation on the IBM 4 Pi EP system with its external configuration and applications software assumed to the characteristic of the centralized quad-redundant avionics systems defined in Phase B

Induction Motors With Rotor Helical Motion

Performance analysis of the twin-armature rotary-linear induction motor, a type of motor with two degrees of mechanical freedom, is the subject of this dissertation. The stator consists of a rotary armature and linear armature placed aside one another. Both armatures have a common rotor which can be either solid or cage rotor. The rotor can move rotary, linearly or with helical motion. The linear motion generates dynamic end effect on both linear and rotary armature. Modeling such an effect in rotary armature is a significant challenge as it requires a solution considering motion with two degrees of mechanical freedom. In other words, the rotor in the model would have to move between two space coordinates (rotary direction as a regular operation of rotary armature and axial direction). Neither of the available FEM software package is currently capable to solve such a problem. The approach used to address linear motion on rotary armature is based on the combination of transient time-stepping finite element model and frequency domain slip frequency technique. An equivalent circuit model is also developed to address helical motion in rotary armature that is based on the model suggested by Duncan to consider dynamic end effects in linear motors. The results obtained from FEM modeling and equivalent circuit model are partially verified by test carried out on experimental model of the motor to validate the theoretical modeling of the motor. FEM performance analysis of the linear armature is rather straightforward as it only involves motion in one direction similar to a conventional linear induction motor. However, due to the finite core length and open magnetic circuit in the direction of motion, the back electromotive forces induced in the three-phase winding are asymmetric and the air gap flux density distribution can still be distorted, even at zero axial speed. This distortion is known as static end effect. Such an effect does not exist in rotary armature. New viewpoint on the end effects in linear armature, which classifies them into two groups, namely as speed-independent (static) and speed-dependent (dynamic) ones, is presented. Static end effect is modelled by quasi-static finite element analysis coupled with equivalent circuit via the lumped parameters. The analysis of the motor with the combination of static and dynamic end effects is done with time-stepping finite element analysis. The approach makes the contribution of each type of the end effect on the performance of the linear motor more visible, than it is possible within approaches presented to this date. Based on this classification, a novel equivalent circuit steady-state model for linear induction motors is also presented. The novelty resides in classification and inclusion of end effects in the equivalent circuit. Duncan model is used to address dynamic end effect and appropriately modified to account for the saturation of back iron and skin effect. The static end effect, which manifests itself by the alternating field component, is represented by additional circuit branch similar to the ones of motor with alternating magnetic field. Each type of the end effects is modeled and included separately. The results regarding determination of basic performance characteristics are compared with those obtained from finite element simulation. The proposed equivalent circuit is more accurate than the conventional equivalent circuit available in literature by considering all major phenomena in linear motors such as static end effects, dynamic end effect and skin effect. Finally, the performance of the motor with solid layer is compared with the one with cage rotor. It is concluded that, in general, motor with the cage rotor has the better performance compared to the solid double layer rotor

Land Value Capture in the United States: Funding Infrastructure and Local Government Services (2022)

Land value capture (LVC) is based on a simple core premise: public action should generate public benefit. As challenges mount from rapid urbanization, deteriorating infrastructure, climate change, and more, this funding source has never been more important to the future of municipalities. LVC tools include special assessments, exactions, impact fees, linkage fees, incentive zoning, transferable development rights with contributions, and upzoning with contributions. To date, American law has permitted LVC tools, subject to some limitations. As a result, land value capture is a viable and potentially important method for funding much-needed public infrastructure, improvements, and programs. Policy makers should seriously consider increasing LVC-based financing.https://digitalcommons.nyls.edu/fac_books/1157/thumbnail.jp