An evaluation of the utilization of remote sensing in resource and environmental management of the Chesapeake Bay region

A nine-month study was conducted to assess the effectiveness of the NASA Wallops Chesapeake Bay Ecological Program in remote sensing. The study consisted of a follow-up investigation and information analysis of actual cases in which remote sensing was utilized by management and research personnel in the Chesapeake Bay region. The study concludes that the NASA Wallops Chesapeake Bay Ecological Program is effective, both in terms of costs and performance

The late time evolution of Gamma-Ray Bursts: ending hyperaccretion and producing flares

We consider the properties of a hyperaccretion model for gamma-ray bursts (GRBs) at the late time when the mass supply rate is expected to decrease with time. We point out that the region in the vicinity of the accretor and the accretor itself can play an important role in determining the rate and time behavior of the accretion and ultimately the energy output. Motivated by numerical simulations and theoretical results, we conjecture that the energy release can be repeatedly stopped and then restarted by the magnetic flux accumulated around the accretor. We propose that the episode or episodes when the accretion resumes correspond to X-ray flares discovered recently in a number of GRBs.Comment: to appear in MNRAS Letters, revised versio

Bearing detection in the presence of two sources of varying coherence using the complex cepstrum

The effect of the presence of two acoustic sources (one, the primary, whose location is to be detected) of varying coherence on a cepstral bearing finding procedure is experimentally studied. The coherence between the acoustic sources was altered by adding random noise of various SNR (signal-to-noise ratio) to the input signal of the primary source; the same base signal being fed to both sources. The results demonstrate that, when block liftering is used, the primary source bearing is reliably estimated for coherences as low as gamma sup 2 greater than or approx equal to 0.5. The results also imply that background noise (unreflected) of SNR greater than or approx equal to 10 dB will not markedly affect the accuracy of the bearing estimation algorithm

Guide for users of the National Transonic Facility

The National Transonic Facility (NTF) is a fan-driven, closed-circuit, continuous flow, pressurized wind tunnel. The test section is 2.5 m x 2.5 m and 7.62 m long with a slotted-wall configuration. The NTF will have a Mach number range from 0.2 to 1.2, with Reynolds number up to 120 10 to the sixth power at Mach 1 (based on a reference length of 0.25 m). The pressure range for the facility will be from 1 to about 9 bars (1 ban = 100 kPa), and the temperature can be varied from 340 to 78 K. This report provides potential users of the NTF with the information required for preliminary planning to test programs and for preliminary layout of models and model supports which may be used in such programs

Theoretical calculation of the electromagnetic response of a radially layered model moon Technical report

Theoretical calculation of electromagnetic response of radially layered moon mode

Modification of the Brink-Axel Hypothesis for High Temperature Nuclear Weak Interactions

We present shell model calculations of electron capture strength distributions in A=28 nuclei and computations of the corresponding capture rates in supernova core conditions. We find that in these nuclei the Brink-Axel hypothesis for the distribution of Gamow-Teller strength fails at low and moderate initial excitation energy, but may be a valid tool at high excitation. The redistribution of GT strength at high initial excitation may affect capture rates during collapse. If these trends which we have found in lighter nuclei also apply for the heavier nuclei which provide the principal channels for neutronization during stellar collapse, then there could be two implications for supernova core electron capture physics. First, a modified Brink-Axel hypothesis could be a valid approximation for use in collapse codes. Second, the electron capture strength may be moved down significantly in transition energy, which would likely have the effect of increasing the overall electron capture rate during stellar collapse.Comment: 15 pages, 19 figure

Borgs in the Org? Organizational Decision Making and Technology

Data warehousing and the development of the World Wide Web both augment information gathering (search) processes in individual decision making by increasing the availability of required information. Imagine, for example, that one wanted to buy new golf clubs. Thirty years ago, the cost of information gathering would likely have limited an individual\u27s search process to geographically proximal vendors and the golf clubs they stocked. Today, a prospective purchaser can log onto the World Wide Web to find out what types of golf clubs are available anywhere; consult databases, chat rooms, and bulletin boards (e.g., epinions.com) to gather product information and user opinions; and compare prices across vendors around the world

Description of a landing site indicator (LASI) for light aircraft operation

An experimental cockpit mounted head-up type display system was developed and evaluated by LaRC pilots during the landing phase of light aircraft operations. The Landing Site Indicator (LASI) system display consists of angle of attack, angle of sideslip, and indicated airspeed images superimposed on the pilot's view through the windshield. The information is made visible to the pilot by means of a partially reflective viewing screen which is suspended directly in frot of the pilot's eyes. Synchro transmitters are operated by vanes, located at the left wing tip, which sense angle of attack and sideslip angle. Information is presented near the center of the display in the form of a moving index on a fixed grid. The airspeed is sensed by a pitot-static pressure transducer and is presented in numerical form at the top center of the display

Neutrino Pair Emission from Hot Nuclei During Stellar Collapse

We present shell-model calculations showing that residual interaction-induced configuration mixing enhances the rate of neutral current de-excitation of thermally excited nuclei into neutrino-antineutrino pairs. Though our calculations reinforce the conclusions of previous studies that this process is the dominant source of neutrino pairs near the onset of neutrino trapping during stellar collapse, our shell-model result has the effect of increasing the energy of these pairs, possibly altering their role in entropy transport in supernovae.Comment: 9 pages, 8 figure