Independent Orbiter Assessment (IOA): Analysis of the displays and controls subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Displays and Controls (D and C) subsystem hardware. The function of the D and C hardware is to provide the crew with the monitor, command, and control capabilities required for management of all normal and contingency mission and flight operations. The D and C hardware for which failure modes analysis was performed consists of the following: Acceleration Indicator (G-METER); Head Up Display (HUD); Display Driver Unit (DDU); Alpha/Mach Indicator (AMI); Horizontal Situation Indicator (HSI); Attitude Director Indicator (ADI); Propellant Quantity Indicator (PQI); Surface Position Indicator (SPI); Altitude/Vertical Velocity Indicator (AVVI); Caution and Warning Assembly (CWA); Annunciator Control Assembly (ACA); Event Timer (ET); Mission Timer (MT); Interior Lighting; and Exterior Lighting. Each hardware item was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode

Overcoming "the Present Limits of the Necessary": Foucault's Conception of a Critique

This essay offers a novel interpretation of Michel Foucault’s original and often misunderstood conception of philosophy as a critical activity. While it is well known that Foucault’s critique undertakes to disclose contingent limits of thought that appear necessary in the present, the nature of the obstacle whose overcoming critique is meant to facilitate remains poorly understood. I argue that this obstacle, “the present limits of the necessary,” resides on the unconscious level of thought Foucault identified as the object of analysis for an archaeology of knowledge. Therefore, Foucault’s conception of a critique can be grasped only against the background of the distinctive conception of thought that informs his archaeological analyses of discursive practices. According to that view, thinking is always shaped by some historically specific system of unconscious norms that define the contingent set of conceptual possibilities subjects are able to recognize in the present. Drawing on Foucault’s largely neglected remarks on the obvious and the habitual, I argue that these unconscious norms of thought are enacted habitually in a discursive practice, which endows them with an appearance of obviousness. In this way, I explain how something contingent appears in the guise of necessity and begins to function as part of the present limits of the necessary. Finally, I argue that the task of a critique to expand the scope of conceptual possibility by disclosing these unconscious limits of thought is motivated by Foucault’s commitment to the ideal of autonomy understood as subject’s self-determination

An example of requirements for Advanced Subsonic Civil Transport (ASCT) flight control system using structured techniques

The requirements are presented for an Advanced Subsonic Civil Transport (ASCT) flight control system generated using structured techniques. The requirements definition starts from initially performing a mission analysis to identify the high level control system requirements and functions necessary to satisfy the mission flight. The result of the study is an example set of control system requirements partially represented using a derivative of Yourdon's structured techniques. Also provided is a research focus for studying structured design methodologies and in particular design-for-validation philosophies

From Display to Labelled Proofs for Tense Logics

We introduce an effective translation from proofs in the display calculus to proofs in the labelled calculus in the context of tense logics. We identify the labelled calculus proofs in the image of this translation as those built from labelled sequents whose underlying directed graph possesses certain properties. For the basic normal tense logic Kt, the image is shown to be the set of all proofs in the labelled calculus G3Kt

Beyond simulation: designing for uncertainty and robust solutions

Simulation is an increasingly essential tool in the design of our environment, but any model is only as good as the initial assumptions on which it is built. This paper aims to outline some of the limits and potential dangers of reliance on simulation, and suggests how to make our models, and our buildings, more robust with respect to the uncertainty we face in design. It argues that the single analyses provided by most simulations display too precise and too narrow a result to be maximally useful in design, and instead a broader description is required, as might be provided by many differing simulations. Increased computing power now allows this in many areas. Suggestions are made for the further development of simulation tools for design, in that these increased resources should be dedicated not simply to the accuracy of single solutions, but to a bigger picture that takes account of a design’s robustness to change, multiple phenomena that cannot be predicted, and the wider range of possible solutions. Methods for doing so, including statistical methods, adaptive modelling, machine learning and pattern recognition algorithms for identifying persistent structures in models, will be identified. We propose a number of avenues for future research and how these fit into design process, particularly in the case of the design of very large buildings

Composite load spectra for select space propulsion structural components

The objective of this program is to develop generic load models with multiple levels of progressive sophistication to simulate the composite (combined) load spectra that are induced in space propulsion system components, representative of Space Shuttle Main Engines (SSME), such as transfer ducts, turbine blades, and liquid oxygen posts and system ducting. The first approach will consist of using state of the art probabilistic methods to describe the individual loading conditions and combinations of these loading conditions to synthesize the composite load spectra simulation. The second approach will consist of developing coupled models for composite load spectra simulation which combine the deterministic models for composite load dynamic, acoustic, high pressure, and high rotational speed, etc., load simulation using statistically varying coefficients. These coefficients will then be determined using advanced probabilistic simulation methods with and without strategically selected experimental data

A two-level structure for advanced space power system automation

The tasks to be carried out during the three-year project period are: (1) performing extensive simulation using existing mathematical models to build a specific knowledge base of the operating characteristics of space power systems; (2) carrying out the necessary basic research on hierarchical control structures, real-time quantitative algorithms, and decision-theoretic procedures; (3) developing a two-level automation scheme for fault detection and diagnosis, maintenance and restoration scheduling, and load management; and (4) testing and demonstration. The outlines of the proposed system structure that served as a master plan for this project, work accomplished, concluding remarks, and ideas for future work are also addressed

Network properties of written human language

We investigate the nature of written human language within the framework of complex network theory. In particular, we analyse the topology of Orwell's \textit{1984} focusing on the local properties of the network, such as the properties of the nearest neighbors and the clustering coefficient. We find a composite power law behavior for both the average nearest neighbor's degree and average clustering coefficient as a function of the vertex degree. This implies the existence of different functional classes of vertices. Furthermore we find that the second order vertex correlations are an essential component of the network architecture. To model our empirical results we extend a previously introduced model for language due to Dorogovtsev and Mendes. We propose an accelerated growing network model that contains three growth mechanisms: linear preferential attachment, local preferential attachment and the random growth of a pre-determined small finite subset of initial vertices. We find that with these elementary stochastic rules we are able to produce a network showing syntactic-like structures

Implementing the Affordable Care Act: Key Design Decisions for State-Based Exchanges

The Affordable Care Act requires the establishment of new health insurance marketplaces -- known as exchanges -- in every state by October 1, 2013. This report examines key design decisions made by the 17 states and the District of Columbia that chose to establish a state-based exchange. The analysis finds that states made significant progress in structuring their exchanges, with states varying in their design decisions. Many states expect to exceed some federal requirements -- to collect and display quality data, for instance -- for 2014. These findings suggest that states capitalized on the flexibility provided by the Affordable Care Act to tailor their exchanges to their unique needs and made decisions with an eye towards outcomes, such as enrollment, consumer experience, and sustainability. These findings also suggest that states' initial decisions will inform future exchange implementation and that states will adjust their decisions while continuing to adopt innovative approaches to accomplish policy goals