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At least 1,243 records · Page 69

The geographical distribution of lightning: Forestry and range requirements and interests

In an attempt to reduce the response time of the initial attack forces to lightning-caused fire, a lightning detection system that effectively locates accurate directions to lightning discharges to over 200 miles from the detection equipment was developed. The system was first tested in Alaska in 1975. Since that time, further development and operational testing led to the implementation of wide area networks. For the 1979 fire season an eight station network in Alaska is to be implemented that will cover virtually all of the lightning-caused fire areas in the state. In the western United States, an eighteen station network that will cover approximately 85% of eleven states is to be implemented. For the first time, large scale ground discharge lightning distribution information is to be available.

Vance, D. L.↗

Integrated Demand Management: The FCA Balancing Algorithm

The Collaborative Trajectory Options Program (CTOP) is a new NextGen function that resides within the FAA’s Traffic Flow Management System (TFMS) software. CTOP was designed to be used in the United States’ national airspace to control the distribution of air traffic demand, both temporally and geographically, through a set of Flow Constrained Areas (FCAs). Each FCA is assigned capacity values that represent an estimated upper limit of manageable demand, and CTOP controls to that capacity by using Expect Departure Clearance Time (EDCT) air traffic control clearances, and/or rerouting flights to an alternate FCA or out of the CTOP completely. CTOP’s decisions about which control options best meet system and user needs are based on the Trajectory Options Set (TOS) submitted by airline operators for each flight. The FCA Balancing Algorithm (FBA) described in this document is a proposed decision support capability that generates CTOP capacity entries for FCAs controlling traffic to a common downstream constraint. The FBA provides an equitable distribution of impact, and addresses the added complexity of assigning FCA capacity values for this specific type of use case, greatly simplifying the FAA air traffic manager’s task.

IDM↗

Second tracking and data relay satellite system (TDRSS) ground terminal - STGT

The STGT will provide high availability command and control and improved services to users of NASA's Space Network in the 1990s and beyond. The Space Network, comprising the TDRSS, will be the primary communications gateway for Space Station Freedom and other user's spacecraft and their ground support elements. The STGT will contain a redundant, distributed computer system providing configuration and control of redundant RF to baseband equipment chains for throughput of user data, for user tracking services and for control and monitoring of the TDR Satellites. An interface with NASA's Network Control Center, located at the Goddard Space Flight Center, provides automated scheduling and control of the STGT. A local TDRSS Operations Control Center for local monitoring and back-up control and an interface with the Domestic Satellite for data distribution will be provided by the STGT. This paper describes the STGT, with emphasis on configuration, control and monitoring of those elements providing TDRSS services to user spacecraft.

Berndt, Allen K.↗

A wall interference assessment/correction interface measurement system for the NASA/ARC 12-ft PWT

Development of complex air vehicle configurations is placing increasing demands on wind tunnel testing capabilities. A major area of concern is wall induced interference. Recent developments in wall interference technology provide a means for assessing and correcting for the wall induced interference using information contained in the distribution of flow variables measured at, or near, the wall. The restoration of the NASA-ARC 12-ft pressure wind tunnel (PWT) provides an opportunity to incorporate a measurement system with which wall interference assessment/correction (WIAC) technology can be applied. In this first phase of the development of a WIAC system for the PWT, the design criteria for the placement and the geometry of wall static pressure orifices were determined with a three step approach. First, the operational environment of the PWT was analyzed as to the requirements for the WIAC system. Second, appropriate wall interference theories were evaluated against the requirements determined from the operational environment. Third, the flow about representative models in the PWT was calculated and, specifically, the pressure signatures at the location of the test section wall were obtained. The number of discrete pressure measurements and their locations were determined by curve fitting the pressure distribution through the discrete measurements and evaluating the resulting error.

Source record↗

The Southern Argentina Agile Meteor Radar Orbital System (SAAMER-OS): An Initial Sporadic Meteoroid Orbital Survey in the Southern Sky

We present an initial survey in the southern sky of the sporadic meteoroid orbital environment obtained with the Southern Argentina Agile MEteor Radar (SAAMER) Orbital System (OS), in which over three-quarters of a million orbits of dust particles were determined from 2012 January through 2015 April. SAAMER-OS is located at the southernmost tip of Argentina and is currently the only operational radar with orbit determination capability providing continuous observations of the southern hemisphere. Distributions of the observed meteoroid speed, radiant, and heliocentric orbital parameters are presented, as well as those corrected by the observational biases associated with the SAAMER-OS operating parameters. The results are compared with those reported by three previous surveys performed with the Harvard Radio Meteor Project, the Advanced Meteor Orbit Radar, and the Canadian Meteor Orbit Radar, and they are in agreement with these previous studies. Weighted distributions for meteoroids above the thresholds for meteor trail electron line density, meteoroid mass, and meteoroid kinetic energy are also considered. Finally, the minimum line density and kinetic energy weighting factors are found to be very suitable for meteoroid applications. The outcomes of this work show that, given SAAMERs location, the system is ideal for providing crucial data to continuously study the South Toroidal and South Apex sporadic meteoroid apparent sources.

meteorites↗

Impact of Probabilistic Weather on Flight Routing Decisions

Flight delays in the United States have been found to increase year after year, along with the increase in air traffic. During the four-month period from May through August of 2005, weather related delays accounted for roughly 70% of all reported delays, The current weather prediction in tactical (within 2 hours) timeframe is at manageable levels, however, the state of forecasting weather for strategic (2-6 hours) timeframe is still not dependable for long-term planning. In the absence of reliable severe weather forecasts, the decision-making for flights longer than two hours is challenging. This paper deals with an approach of using probabilistic weather prediction for Traffic Flow Management use, and a general method using this prediction for estimating expected values of flight length and delays in the National Airspace System (NAS). The current state-of-the-art convective weather forecasting is employed to aid the decision makers in arriving at decisions for traffic flow and flight planing. The six-agency effort working on the Next Generation Air Transportation System (NGATS) have considered weather-assimilated decision-making as one of the principal foci out of a list of eight. The weather Integrated Product Team has considered integrated weather information and improved aviation weather forecasts as two of the main efforts (Ref. 1, 2). Recently, research has focused on the concept of operations for strategic traffic flow management (Ref. 3) and how weather data can be integrated for improved decision-making for efficient traffic management initiatives (Ref. 4, 5). An overview of the weather data needs and benefits of various participants in the air traffic system along with available products can be found in Ref. 6. Previous work related to use of weather data in identifying and categorizing pilot intrusions into severe weather regions (Ref. 7, 8) has demonstrated a need for better forecasting in the strategic planning timeframes and moving towards a probabilistic description of weather (Ref. 9). This paper focuses on. specified probability in a local region for flight intrusion/deviation decision-making. The process uses a probabilistic weather description, implements that in a air traffic assessment system to study trajectories of aircraft crossing a cut-off probability contour. This value would be useful for meteorologists in creating optimum distribution profiles for severe weather, Once available, the expected values of flight path and aggregate delays are calculated for efficient operations. The current research, however, does not deal with the issue of multiple cell encounters, as well as echo tops, and will be a topic of future work.

Sheth, Kapil↗

Probabilistic Survivability Versus Time Modeling

This technical paper documents Kennedy Space Centers Independent Assessment team work completed on three assessments for the Ground Systems Development and Operations (GSDO) Program to assist the Chief Safety and Mission Assurance Officer (CSO) and GSDO management during key programmatic reviews. The assessments provided the GSDO Program with an analysis of how egress time affects the likelihood of astronaut and worker survival during an emergency. For each assessment, the team developed probability distributions for hazard scenarios to address statistical uncertainty, resulting in survivability plots over time. The first assessment developed a mathematical model of probabilistic survivability versus time to reach a safe location using an ideal Emergency Egress System at Launch Complex 39B (LC-39B); the second used the first model to evaluate and compare various egress systems under consideration at LC-39B. The third used a modified LC-39B model to determine if a specific hazard decreased survivability more rapidly than other events during flight hardware processing in Kennedys Vehicle Assembly Building (VAB).Based on the composite survivability versus time graphs from the first two assessments, there was a soft knee in the Figure of Merit graphs at eight minutes (ten minutes after egress ordered). Thus, the graphs illustrated to the decision makers that the final emergency egress design selected should have the capability of transporting the flight crew from the top of LC 39B to a safe location in eight minutes or less. Results for the third assessment were dominated by hazards that were classified as instantaneous in nature (e.g. stacking mishaps) and therefore had no effect on survivability vs time to egress the VAB. VAB emergency scenarios that degraded over time (e.g. fire) produced survivability vs time graphs that were line with aerospace industry norms.

Joyner, James J., Sr.↗

Experiences with hypercube operating system instrumentation

The difficulties in conceptualizing the interactions among a large number of processors make it difficult both to identify the sources of inefficiencies and to determine how a parallel program could be made more efficient. This paper describes an instrumentation system that can trace the execution of distributed memory parallel programs by recording the occurrence of parallel program events. The resulting event traces can be used to compile summary statistics that provide a global view of program performance. In addition, visualization tools permit the graphic display of event traces. Visual presentation of performance data is particularly useful, indeed, necessary for large-scale parallel computers; the enormous volume of performance data mandates visual display.

Reed, Daniel A.↗

Distributed Scheduling Architecture for Multi-Center Time-Based Metering

The Traffic Management Advisor (TMA) is an air traffic control automation system currently in use in seven Air Route Traffic Control Centers (ARTCCs) to enable time based metering to busy airports within their airspace. However, this system is limited to operation within a single ARTCC, within about a 200 nautical mile radius of the airport, and on relatively simple streams of traffic. The need for coordinated metering within a greater (300+ nautical mile) radius of an airport, on streams of traffic with significant branching, and across ARTCC boundaries, has been identified. Early tests revealed that TMA could not simply be scaled up to handle such a problem. Instead, a loosely coupled hierarchy of schedules, in which constraints from downstream schedules are passed upstream, is required. Such an architecture reduces the reliance on distant projections of arrival times, making schedules robust to changes in sequence and to additions of aircraft (such as aircraft departing inside the system s scheduling horizon). This architecture is also scaleable, easily reconfigurable, and can be networked together. As such, it can be adapted for use in any size or configuration of airspace and with any number of airports delivering restrictions. An implementation of this distributed scheduling architecture is currently undergoing testing in the TMA-Multi Center system. This paper describes the architecture and its motivation.

Landry, Steven↗

Observations on degradation of UV systems on Nimbus spacecraft

Broad band photometer experiments in the 1200 to 3000 A have been operating on Nimbus 3 and 4 since April 1969 for the purpose of determining the nature of variations in the UV solar irradiance. An Ebert-Fastie double monochromator has been measuring the solar irradiance and earth radiance from 2500 to 3400 A for the determination of global atmospheric ozone distributions since April 1970. From prelaunch testing and an evaluation of the flight data it is concluded that the principal source of degradation is probably the spacecraft. The degradation produces a characteristic signal loss and change in angular response of the system which might be explained by micron sized droplets becoming a permanent residue under the influence of solar UV radiation.

Heath, D. F.↗

Fireballs in the Sky: An Augmented Reality Citizen Science Program

Fireballs in the Sky is an innovative Australian citizen science program that connects the public with the research of the Desert Fireball Network (DFN). This research aims to understand the early workings of the solar system, and Fireballs in the Sky invites people around the world to learn about this science, contributing fireball sightings via a user-friendly augmented reality mobile app. Tens of thousands of people have downloaded the app world-wide and participated in the science of meteoritics. The Fireballs in the Sky app allows users to get involved with the Desert Fireball Network research, supplementing DFN observations and providing enhanced coverage by reporting their own meteor sightings to DFN scientists. Fireballs in the Sky reports are used to track the trajectories of meteors - from their orbit in space to where they might have landed on Earth. Led by Phil Bland at Curtin University in Australia, the Desert Fireball Network (DFN) uses automated observatories across Australia to triangulate trajectories of meteorites entering the atmosphere, determine pre-entry orbits, and pinpoint their fall positions. Each observatory is an autonomous intelligent imaging system, taking 1000 by 36 megapixel all-sky images throughout the night, using neural network algorithms to recognize events. They are capable of operating for 12 months in a harsh environment, and store all imagery collected. We developed a completely automated software pipeline for data reduction, and built a supercomputer database for storage, allowing us to process our entire archive. The DFN currently stands at 50 stations distributed across the Australian continent, covering an area of 2.5 million square kilometers. Working with DFN's partners at NASA's Solar System Exploration Research Virtual Institute, the team is expanding the network beyond Australia to locations around the world. Fireballs in the Sky allows a growing public base to learn about and participate in this exciting research.

Day, Brian↗

Pioneer 10 mission - Summary of scientific results from the encounter with Jupiter

Data on the Jovian atmosphere and radiation environment transmitted by Pioneer 10 as it passed by Jupiter are discussed. The presence of a strong magnetic field, of energetic electron precursers, and of flat disk-shaped particle distribution is noted at a distance of 360 Jovian radii from the planet. Previously available data on Jovian satellites are augmented from Pioneer 10 data. The normal operation of the data collecting and transmitting systems of the mission after encounter with Jupiter is noted.

Opp, A. G.↗

Solar power satellite system definition study, volume 4, phase 2

Results of an overall evaluation of the solar power satellite concept are reported. Specific topics covered include: solid state sandwich configuration; parametric development of reliability design; power distribution system for solid state solar power satellites; multibeam transmission; GEO base system configuration; suppression of the heavy lift launch vehicle trajectory; conceptual design of an offshore space center facility; solar power satellite development and operations scenario; and microwave power transmission technology, advancement, development, and facility requirements.

Source record↗

DIAL with heterodyne detection including speckle noise: Aircraft/shuttle measurements of O3, H2O, and NH3 with pulsed tunable CO2lasers

A parametric analysis of DIAL sensitivity with heterodyne detection is presented and comparisons with direct detection are discussed. Examples are given for monitoring vertical distributions of O3, H2O, and NH3 using a ground-, aircraft-, or shuttle-based pulsed tunable CO2 laser DIAL system. Results indicate that maximum sensitivity at minimum laser energy per measurement requires multiple pulse operation with the energy per pulse selected so that the measured photon rate is approximately equal to the detector IF bandwidth. Measurement sensitivities can be maximized and interference effects minimized by fine adjustment of measurement frequencies using the tunability of high pressure lasers. The use of rare isotope lasers minimizes loss due to CO2 atmospheric absorption.

Brockman, P.↗

Optical processing for future computer networks

In the development of future data management systems, such as the NASA Space Station, a major problem represents the design and implementation of a high performance communication network which is self-correcting and repairing, flexible, and evolvable. To obtain the goal of designing such a network, it will be essential to incorporate distributed adaptive network control techniques. The present paper provides an outline of the functional and communication network requirements for the Space Station data management system. Attention is given to the mathematical representation of the operations being carried out to provide the required functionality at each layer of communication protocol on the model. The possible implementation of specific communication functions in optics is also considered.

Husain, A.↗

Infrared surface temperature measurements for the surface tension driven convection experiment

In support of the Surface Tension Driven Convection Experiment (STDCE), a planned space transportation system (STS) flight experiment, a commercially available infrared thermal imaging system is used to quantify the imposed thermal signature along the free surface. The system was tested and calibrated for the STDCE with ground-based equivalents of the STDCE hardware. Before using the system, consideration was given to the radiation characteristics of the target (silicone oil). Absorption coefficients were calculated to understand the surface depth as seen by the imager and the penetration depth of the surface heater (CO2 laser). The performance and operational specifications for the imager and image processing system are described in detail to provide an understanding of the equipment. Measurements made with the system were compared to thermocouple measurements and a calculated surface temperature distribution. This comparison showed that in certain regions the IR imager measurements were within 5 percent of the overall temperature difference across the free surface. In other regions the measurements were within + or - 10 percent of the overall temperature gradient across the free surface. The effective emissivity of silicone oil for these experimental conditions was also determined. Measurement errors and their possible solutions are discussed.

Pline, Alexander D.↗

The Aerospace Energy Systems Laboratory: A BITBUS networking application

The NASA Ames-Dryden Flight Research Facility developed a computerized aircraft battery servicing facility called the Aerospace Energy Systems Laboratory (AESL). This system employs distributed processing with communications provided by a 2.4-megabit BITBUS local area network. Customized handlers provide real time status, remote command, and file transfer protocols between a central system running the iRMX-II operating system and ten slave stations running the iRMX-I operating system. The hardware configuration and software components required to implement this BITBUS application are required.

Glover, Richard D.↗

NELS 2.0 - A general system for enterprise wide information management

NELS, the NASA Electronic Library System, is an information management tool for creating distributed repositories of documents, drawings, and code for use and reuse by the aerospace community. The NELS retrieval engine can load metadata and source files of full text objects, perform natural language queries to retrieve ranked objects, and create links to connect user interfaces. For flexibility, the NELS architecture has layered interfaces between the application program and the stored library information. The session manager provides the interface functions for development of NELS applications. The data manager is an interface between session manager and the structured data system. The center of the structured data system is the Wide Area Information Server. This system architecture provides access to information across heterogeneous platforms in a distributed environment. There are presently three user interfaces that connect to the NELS engine; an X-Windows interface, and ASCII interface and the Spatial Data Management System. This paper describes the design and operation of NELS as an information management tool and repository.

Smith, Stephanie L.↗