Map-Based Navigation in a Graphical MOO

Traditional MUDs and MOOs lack support for global wareness and simple navigation. These problems can be addressed by the introduction of a map-based navigation tool. In this paper we report on the design and evaluation of such a tool for MOOsburg, a graphical 2D MOO based on the town of Blacksburg, Virginia. The tool supports exploration and place-based tasks in the MOO. It also allows navigation of a large-scale map and encourages users to develop survey knowledge of the town. An evaluation revealed some initial usability problems with our prototype and suggested new design ideas that may better support users. Using these results, the lessons learned about map-based navigation are presented

Autonomous prealignment of a docking mechanism

Proposed future space exploration, such as lunar and Martian expeditions, will require autonomous docking of space vehicles. One proposed candidate method of autonomous docking utilizes a actively controlled parallel manipulator. Operation of the proposed docking manipulator can be segmented into four successive events: prealignment, capture/latching, attenuation, and structural rigidization. This paper discusses the development and testing of a digitally controlled, six-degree-of-freedom (6-DOF), parallel manipulator for the prealignment segment of a docking spacecraft

Evaluation of telerobotic systems using an instrumented task board

An instrumented task board was developed at NASA Marshall Space Flight Center (MSFC). An overview of the task board design, and current development status is presented. The task board was originally developed to evaluate operator performance using the Protoflight Manipulator Arm (PFMA) at MSFC. The task board evaluates tasks for Orbital Replacement Unit (ORU), fluid connect and transfers, electrical connect/disconnect, bolt running, and other basic tasks. The instrumented task board measures the 3-D forces and torques placed on the board, determines the robot arm's 3-D position relative to the task board using IR optics, and provides the information in real-time. The PFMA joint input signals can also be measured from a breakout box to evaluate the sensitivity or response of the arm operation to control commands. The data processing system provides the capability for post processing of time-history graphics and plots of the PFMA positions, the operator's actions, and the PFMA servo reactions in addition to real-time force/torque data presentation. The instrumented task board's most promising use is developing benchmarks for NASA centers for comparison and evaluation of telerobotic performance

Characteristics of Four Agricultural Crops Established as Northern Bobwhite Brood Habitat

Small plots of agricultural crops are often planted in the Southeast for northern bobwhite (Colinus virginianus) management. Often these are viewed as primarily winter habitat, and assumed to provide summer habitat. We evaluated the macroinvertebrate and vegetative structure of millet, sorghum, wheat, and soybean plots on a cotton farm to assess their value as bobwhite brood habitat. During June and July 1999 and June, July, and August 2000, we studied 5 blocks, each planted with all 4 agricultural crops. We measured invertebrate abundance along a 15-meter transect in each plot using vacuum sampling and height/density of vegetation. Visual obstruction readings (VOR) were highest in millet and sorghum, followed by wheat and then soybean (P \u3c 0.001). Macroinvertebrate numbers differed among cover types (P \u3c 0.001), but macroinvertebrate weights did not (P = 0.14). Among important Orders, Coleoptera, Hemiptera, Diptera, and Homoptera were found in greater numbers in millet. Numbers of Hymenoptera did not differ among crops. In most cases, millet yielded the highest biomass and numbers of macroinvertebrates, followed by sorghum. Soybeans and wheat had fewer macroinvertebrates among the crops studied. On our study area it appears that millet provides the best brood habitat, although sorghum appears to provide a second useful crop. Thus, among these crops we recommend use of millet plots as brood habitat for northern bobwhite chicks

Northern Bobwhite Habitat Modeling on a Military Installation in Relation to Red-Cockaded Woodpecker Management

The Department of Defense (DoD) manages natural resources on ~ 8 million ha of land. A top priority for much of this land is to restore and maintain native ecosystems and associated wildlife species. However, given the typical location (i.e., threatened ecosystems) and size of DoD lands, management conflicts usually occur among endangered/threatened species and game species. Military installations in the southeastern United States are commonly managed to protect red-cockaded woodpecker (Piciodes borealis) (RCW) populations and longleaf-wiregrass ecosystems. Mandated RCW management is not entirely compatible with other declining species such as northern bobwhite (Colinus virginianus). Land managers need to be equipped with spatially-explicit habitat models that can be used to make informed decisions on how to manage for particular species. Data collected on Fort Gordon Military Installation, Georgia from male bobwhite whistle counts during summer 2010 and 2011 will be used to construct competing models on the relationship between RCW management and other habitat structure metrics as it relates to bobwhite habitat suitability. These data were collected using a robust occupancy sampling design to allow open and closed population assumptions. Preliminary data suggests the RCW habitat ranking matrix is a poor predictor of bobwhite habitat suitability and, more alarmingly, RCW population performance. These models will assist natural resource managers on DoD land in making efficient decisions in the face of uncertainty

Within‑marsh and Landscape Features Structure Ribbed Mussel Distribution in Georgia, USA, Marshes

Ribbed mussels, Geukensia demissa, are marsh fauna that are used in coastal management and restoration due to the ecosystem services they provide. Ribbed mussel restoration efforts may be improved with a greater understanding of the environmental drivers of ribbed mussel distribution at multiple spatial scales to predict areas where restoration could be successful. This study sought to estimate the effects of within-marsh (4 m) and landscape (500 m) factors on ribbed mussel distribution. Ribbed mussel densities were surveyed at 11 sites along the coast of Georgia, USA, and overlaid with spatial data for within-marsh factors (elevation, distance to marsh features, slope) as well as landscape factors (percent cover by subtidal creek, forest, and development within a 500-m radius). The distribution model was then validated using three previously unsurveyed marshes and explained 55% of the variance in ribbed mussel abundance. Ribbed mussel abundances and occupancy were most sensitive to changes in within-marsh factors (elevation and distance to subtidal creeks, bodies of water inundated during the full tidal cycle) but were also sensitive to landscape features (percent landcover of forests and development). The highest ribbed mussel densities were found in mid-elevation areas (~ 0.7 m NAVD88), far from subtidal creeks, and in marshes surrounded with forest and development. These results contrast with distributions in the northeastern USA, where ribbed mussels are distributed along subtidal creek banks. This work suggests that restoration may be most effective when focused on appropriate elevations and at locations away from the marsh-creek ecotone

The Virgo Alignment Puzzle in Propagation of Radiation on Cosmological Scales

We reconsider analysis of data on the cosmic microwave background on the largest angular scales. Temperature multipoles of any order factor naturally into a direct product of axial quantities and cosets. Striking coincidences exist among the axes associated with the dipole, quadrupole, and octupole CMB moments. These axes also coincide well with two other axes independently determined from polarizations at radio and optical frequencies propagating on cosmological scales. The five coincident axes indicate physical correlation and anisotropic properties of the cosmic medium not predicted by the conventional Big Bang scenario. We consider various mechanisms, including foreground corrections, as candidates for the observed correlations. We also consider whether the propagation anomalies may be a signal of ``dark energy'' in the form of a condensed background field. Perhaps {\it light propagation} will prove to be an effective way to look for the effects of {\it dark energy}.Comment: 24 pages, 4 figures, minor changes, no change in result or conclusions. to appear in IJMP

Database management and analysis of fisheries in Illinois: Final report, 1 March 1999-28 February 2002

Issued May 2002; F-69-RReport issued on: May 200