Support for User Interfaces for Distributed Systems

An extensible Java(TradeMark) software framework supports the construction and operation of graphical user interfaces (GUIs) for distributed computing systems typified by ground control systems that send commands to, and receive telemetric data from, spacecraft. Heretofore, such GUIs have been custom built for each new system at considerable expense. In contrast, the present framework affords generic capabilities that can be shared by different distributed systems. Dynamic class loading, reflection, and other run-time capabilities of the Java language and JavaBeans component architecture enable the creation of a GUI for each new distributed computing system with a minimum of custom effort. By use of this framework, GUI components in control panels and menus can send commands to a particular distributed system with a minimum of system-specific code. The framework receives, decodes, processes, and displays telemetry data; custom telemetry data handling can be added for a particular system. The framework supports saving and later restoration of users configurations of control panels and telemetry displays with a minimum of effort in writing system-specific code. GUIs constructed within this framework can be deployed in any operating system with a Java run-time environment, without recompilation or code changes

Observations of DG Tauri with the Keck Interferometer

We present the first science results from the Keck Interferometer, a direct-detection infrared interferometer utilizing the two 10-meter Keck telescopes. The instrument and system components are briefly described. We then present observations of the T Tauri object DG Tau, which is resolved by the interferometer. The resolved component has a radius of 0.12 to 0.24 AU, depending on the assumed stellar and extended component fluxes and the model geometry used. Possible origins and implications of the resolved emission are discussed.Comment: 10 pages, 2 figures, to appear in ApJ Letter

The Magellan Telescopes: A Performance Update

The Magellan Baade and Clay telescopes regularly produce images of ~0.5" in natural seeing. We review efforts to improve collimation, active optics response, and telescope guiding and pointing to optimize the performance of the telescopes. Procedures have been developed to monitor and analyze image quality delivered by the imaging science instruments. Improved models have been developed to correct for flexure of the telescope and primary mirror under gravity loading. Collimation has been improved using a "two-probe" Shack-Hartman technique to measure field aberrations. Field acquisition performance has been improved by implementing an open loop model for the primary mirror control. Telescope pointing has been improved by regular monitoring and adjustments to improve acquisition times

Estimating runoff volumes and flood hydrographs in the Colorado River Basin, Southern Utah /

"Prepared in cooperation with the Utah Department of Transportation."Bibliography: leaf 18.Mode of access: Internet

Simulation of five ground-water withdrawal projections for the Black Mesa area, Navajo and Hopi Indian Reservations, Arizona /

"February 1988."Shipping list no.: 88-221-P.Bibliography: p. 51.Mode of access: Internet

Floods of October 1983 in southeastern Arizona /

"March 1989."Shipping list no.: 89-331-P.Bibliography: p. 34-35.Mode of access: Internet

The weight of the flood‐of‐record in flood frequency analysis

The standard approach to flood frequency analysis (FFA) fits mathematical functions to sequences of historic flood data and extrapolates the tails of the distribution to estimate the magnitude and likelihood of extreme floods. Here, we identify the most exceptional floods in the United States as compared against other major floods at the same location, and evaluate how the flood-of-record (Qmax) influences FFA estimates. On average, floods-of-record are 20% larger by discharge than their second-place counterparts (Q2), and 212 gages (7.3%) have Qmax:Q2 ratios greater than two. There is no clear correspondence between the Qmax:Q2 ratio and median instantaneous discharge, and exceptional floods do not become less likely with time. Excluding Qmax from the FFA causes the median 100-year flood to decline by −10.5%, the 200-year flood by −11.8%, and the 500-year flood by −13.4%. Even when floods are modelled using a heavy tail distribution, the removal of Qmax yields significantly “lighter” tails and underestimates the risk of large floods. Despite the temporal extension of systematic hydrological observations in the United States, FFA is still sensitive to the presence of extreme events within the sample used to calculate the frequency curve