A system for synthetic vision and augmented reality in future flight decks

Rockwell Science Center is investigating novel human-computer interaction techniques for enhancing the situational awareness in future flight decks. One aspect is to provide intuitive displays that provide the vital information and the spatial awareness by augmenting the real world with an overlay of relevant information registered to the real world. Such Augmented Reality (AR) techniques can be employed during bad weather scenarios to permit flying in Visual Flight Rules (VFR) in conditions which would normally require Instrumental Flight Rules (IFR). These systems could easily be implemented on heads-up displays (HUD). The advantage of AR systems vs. purely synthetic vision (SV) systems is that the pilot can relate the information overlay to real objects in the world, whereas SV systems provide a constant virtual view, where inconsistencies can hardly be detected. The development of components for such a system led to a demonstrator implemented on a PC. A camera grabs video images which are overlaid with registered information. Orientation of the camera is obtained from an inclinometer and a magnetometer; position is acquired from GPS. In a possible implementation in an airplane, the on-board attitude information can be used for obtaining correct registration. If visibility is sufficient, computer vision modules can be used to fine-tune the registration by matching visual cues with database features. This technology would be especially useful for landing approaches. The current demonstrator provides a frame-rate of 15 fps, using a live video feed as background with an overlay of avionics symbology in the foreground. In addition, terrain rendering from a 1 arc sec. digital elevation model database can be overlaid to provide synthetic vision in case of limited visibility. For true outdoor testing (on ground level), the system has been implemented on a wearable computer

Sigma-Model Aether

Theories of low-energy Lorentz violation by a fixed-norm "aether" vector field with two-derivative kinetic terms have a globally bounded Hamiltonian and are perturbatively stable only if the vector is timelike and the kinetic term in the action takes the form of a sigma model. Here we investigate the phenomenological properties of this theory. We first consider the propagation of modes in the presence of gravity, and show that there is a unique choice of curvature coupling that leads to a theory without superluminal modes. Experimental constraints on this theory come from a number of sources, and we examine bounds in a two-dimensional parameter space. We then consider the cosmological evolution of the aether, arguing that the vector will naturally evolve to be orthogonal to constant-density hypersurfaces in a Friedmann-Robertson-Walker cosmology. Finally, we examine cosmological evolution in the presence of an extra compact dimension of space, concluding that a vector can maintain a constant projection along the extra dimension in an expanding universe only when the expansion is exponential.Comment: 8 pages, 2 figures; fixed minor typo and changed references in v

An Analysis of the Dynamics of the US Commercial Air Transportation System

Major trends in the airline industry are analyzed to highlight key dynamics that govern the US domestic air transportation system. The hypothesis is that air travel supply and demand equilibriums, a reliance on outside capital, and intra-industry competition are among the most critical forces that are driving the current restructuring of the airline industry. Data on airline operational and financial performance is used to trace these dynamics as the industry evolved through periods of industry deregulation, an economic growth bubble, and the aftermath of the attacks of September 11, 2001. The thesis identifies the post-deregulation development of hub-and-spoke networks and yield management systems as the key forces that would set the stage for a bifurcation of the air travel market during a cycle of economic growth in the late 1990’s. During this bubble economy, the dynamics of supply and demand fundamentally shifted as the major carriers focused on high-revenue, high-cost operations and travelers began to flock to newer low-fare, low-cost carriers. With the end of the economic growth cycle in 2000, the bifurcation of the airline industry began to affect revenues and profits at the major carriers. Massive and unprecedented industry losses would ensue, and would be compounded by the attacks of 9/11. Airline operational strategies in response to 9/11 and longer-term restructuring efforts are discussed in order to further identify the key dynamics affecting the air transportation system. These dynamics are synthesized and then discussed within the broader context of the air transportation system, the impact of air travel on the economy and mobility, and the role of government.MIT Global Airline Industry Program, Alfred P. Sloan Foundation

Evaluation of seals for high-performance cryogenic turbomachines

An approach to computing flow and dynamic characteristics for seals or bearings is discussed. The local average velocity was strongly influenced by inlet and exit effects and fluid injection, which in turn drove zones of secondary flow. For the restricted three-dimensional model considered, the integral averaged results were in reasonable agreement with selected data. Unidirectional pressure measurements alone were insufficient to define such flow variations. However, for seal and bearing leakage correlations the principles of corresponding states were found to be useful. Also discussed are three phenomena encountered during testing of three eccentric nonrotating seal configurations for the Space Shuttle Main Engine (SSME) Program. Fluid injection, choking within a seal, and pressure profile crossover are related to postulated zones of secondary flow or separation and to direct stiffness

Air Transportation And Socioeconomic Connectivity In The United States Since Deregulation

In light of ongoing threats to the viability of traditional airline business models and the provision of air service in the United States, this paper studies the fundamental interdependence of the national economy and the air transportation system. A conceptual framework has been developed to identify the mechanisms that enable air transportation to shape regional economic productivity and social connectivity. Regional economic census data is combined with airline traffic and financial data to illustrate the changes in supply and demand for air travel after the deregulation of the airline industry in 1978. The paper focuses on how the utilization of air transportation system supports economic and social activities across greater distances than would otherwise be possible—changing the economic geography of market access. An analysis of industry restructuring after the economic bubble and the attacks of September 11, 2001 are also used to look at the potential impacts on economic activity at the regional and national levels

Acoustic interactions between an altitude test facility and jet engine plumes: Theory and experiments

The overall objective of the described effort was to develop an understanding of the physical mechanisms involved in the flow/acoustic interactions experienced in full-scale altitude engine test facilities. This is done by conducting subscale experiments and through development of a theoretical model. Model cold jet experiments with an axisymmetric convergent nozzle are performed in a test setup that stimulates a supersonic jet exhausting into a cylindrical diffuser. The measured data consist of detailed flow visualization data and acoustic spectra for a free and a ducted plume. It is shown that duct resonance is most likely responsible by theoretical calculations. Theoretical calculations also indicate that the higher discrete tones observed in the measurements are related to the screech phenomena. Limited experiments on the sensitivity of a free 2-D, C-D nozzle to externally imposed sound are also presented. It is shown that a 2-D, C-D nozzle with a cutback is less excitable than a 2-D C-D nozzle with no cutback. At a pressure ratio of 1.5 unsteady separation from the diverging walls of the nozzle is noticed. This separation switches from one wall to the opposite wall thus providing an unsteady deflection of the plume. It is shown that this phenomenon is related to the venting provided by the cutback section

X-ray and Near-IR Variability of the Anomalous X-ray Pulsar 1E 1048.1-5937: From Quiescence Back to Activity

(Abridged) We report on new and archival X-ray and near-infrared observations of the anomalous X-ray pulsar 1E 1048.1-5937 performed between 2001-2007 with RXTE, CXO, Swift, HST, and VLT. During its ~2001-2004 active period, 1E 1048.-5937 exhibited two large, long-term X-ray pulsed-flux flares as well as short bursts, and large (>10x) torque changes. Monitoring with RXTE revealed that the source entered a phase of timing stability in 2004; at the same time, a series of four simultaneous observations with CXO and HST in 2006 showed that its X-ray flux and spectrum and near-IR flux, all variable prior to 2005, stabilized. The near-IR flux, when detected by HST (H~22.7 mag) and VLT (K_S~21.0 mag), was considerably fainter than previously measured. Recently, in 2007 March, this newfound quiescence was interrupted by a sudden flux enhancement, X-ray spectral changes and a pulse morphology change, simultaneous with a large spin-up glitch and near-IR enhancement. Our RXTE observations revealed a sudden pulsed flux increase by a factor of ~3 in the 2-10 keV band. In observations with CXO and Swift, we found that the total X-ray flux increased much more than the pulsed flux, reaching a peak value of >7 times the quiescent value (2-10 keV). With these recent data, we find a strong anti-correlation between X-ray flux and pulsed fraction, and a correlation between X-ray spectral hardness and flux. Simultaneously with the radiative and timing changes, we observed a significant X-ray pulse morphology change such that the profile went from nearly sinusoidal to having multiple peaks. We compare these remarkable events with other AXP outbursts and discuss implications in the context of the magnetar model and other models of AXP emission.Comment: 13 pages (6 figures) in emulateapj style. Accepted for publication in ApJ. New version includes referee's corrections; split Figure 1 into 2 figures; modified Figs. 4b and 6b; rearranged and renumbered of some figures and sections; added an X-ray dataset; improved analysis of pulse morphology and pulsed fraction; added paragraph to sec. 3.2.