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All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Microgravity acceleration measurement environment characterization

The Space Acceleration Measurement System (SAMS) is a general-purpose instrumentation system designed to measure the accelerations onboard the shuttle Orbiter and shuttle/Spacelab vehicles. These measurements are used to support microgravity experiments and investigations into the microgravity environment of the vehicle. Acceleration measurement can be made at locations remote from the SAMS main instrumentation unit by the use of up to three remote triaxial sensor heads. The SAMS was developed by NASA's Lewis Research Center (LeRC) in support of NASA's microgravity science programs. In the past, numerous acceleration measurement systems have flown on various space missions. These systems were tailored to measure accelerations for a narrow set of requirements and were limited in bandwidth, dynamic range, and recording capability. In addition, these systems were mission-peculiar and not easily modified for other applications or missions. The result has been an inability to accurately assess the expected microgravity environment prior to a mission for a particular experiment and/or location. The prime science objective for SAMS on the SL-J mission will be to measure the accelerations experienced by a multitude of experiments in the two racks of the Japanese First Materials Processing Test (FMPT). The FMPT consists of a variety of materials science and life science experiments contained in racks no. 7 and no. 10. The SAMS data will be made available to the FMPT principal investigators after the mission for their analysis with the FMPT data. A secondary science objective for SAMS will be the characterization of the acceleration environment of the Spacelab module. This will include an analysis of the acceleration transfer function of the Spacelab module which will utilize the FMPT acceleration measurement along with measurements at the rack no. 9 structure. Another analytical effort to be undertaken is a general characterization of the acceleration environment of the Spacelab as an orbiting laboratory. These analysis efforts will be in conjunction with similar measurements and analyses on other SAMS Spacelab missions.

Delombard, Richard↗
NASA NTRS1994

Turbine design and application volumes 1, 2, and 3

NASA has an interest in turbines related primarily to aeronautics and space applications. Airbreathing turbine engines provide jet and turboshaft propulsion, as well as auxiliary power for aircraft. Propellant-driven turbines provide rocket propulsion and auxiliary power for spacecraft. Closed-cycle turbine engines using inert gases, organic fluids, and metal fluids have been studied for providing long-duration electric power for spacecraft. Other applications of interest for turbine engines include land-vehicle (cars, trucks, buses, trains, etc.) propulsion power and ground-based electrical power. In view of the turbine-system interest and efforts at Lewis Research Center, a course entitled 'Turbine Design and Application' was presented during 1968-69 as part of the In-house Graduate Study Program. The course was somewhat revised and again presented in 1972-73. Various aspects of turbine technology were covered including thermodynamic and fluid-dynamic concepts, fundamental turbine concepts, velocity diagrams, losses, blade aerodynamic design, blade cooling, mechanical design, operation, and performance. The notes written and used for the course have been revised and edited for publication. Such a publication can serve as a foundation for an introductory turbine course, a means for self-study, or a reference for selected topics. Any consistent set of units will satisfy the equations presented. Two commonly used consistent sets of units and constant values are given after the symbol definitions. These are the SI units and the U.S. customary units. A single set of equations covers both sets of units by including all constants required for the U.S. customary units and defining as unity those not required for the SI units. Three volumes are compiled into one.

Engine design↗
NASA NTRS2001

A Unique Power System For The ISS Fluids And Combustion Facility

Unique power control technology has been incorporated into an electrical power control unit (EPCU) for the Fluids and Combustion Facility (FCF). The objective is to maximize science throughput by providing a flexible power system that is easily reconfigured by the science payload. Electrical power is at a premium on the International Space Station (ISS). The EPCU utilizes advanced power management techniques to maximize the power available to the FCF experiments. The EPCU architecture enables dynamic allocation of power from two ISS power channels for experiments. Because of the unique flexible remote power controller (FRPC) design, power channels can be paralleled while maintaining balanced load sharing between the channels. With an integrated and redundant architecture, the EPCU can tolerate multiple faults and still maintain FCF operation. It is important to take full advantage of the EPCU functionality. The EPCU acts as a buffer between the experimenter and the ISS power system with all its complex requirements. However, FCF science payload developers will still need to follow guidelines when designing the FCF payload power system. This is necessary to ensure power system stability, fault coordination, electromagnetic compatibility, and maximum use of available power for gathering scientific data.

Fox, David A.↗
NASA NTRS2005

Space-Based Range Safety and Future Space Range Applications

The National Aeronautics and Space Administration (NASA) Space-Based Telemetry and Range Safety (STARS) study is a multiphase project to demonstrate the performance, flexibility and cost savings that can be realized by using space-based assets for the Range Safety [global positioning system (GPS) metric tracking data, flight termination command and range safety data relay] and Range User (telemetry) functions during vehicle launches and landings. Phase 1 included flight testing S-band Range Safety and Range User hardware in 2003 onboard a high-dynamic aircraft platform at Dryden Flight Research Center (Edwards, California, USA) using the NASA Tracking and Data Relay Satellite System (TDRSS) as the communications link. The current effort, Phase 2, includes hardware and packaging upgrades to the S-band Range Safety system and development of a high data rate Ku-band Range User system. The enhanced Phase 2 Range Safety Unit (RSU) provided real-time video for three days during the historic Global Flyer (Scaled Composites, Mojave, California, USA) flight in March, 2005. Additional Phase 2 testing will include a sounding rocket test of the Range Safety system and aircraft flight testing of both systems. Future testing will include a flight test on a launch vehicle platform. This paper discusses both Range Safety and Range User developments and testing with emphasis on the Range Safety system. The operational concept of a future space-based range is also discussed.

Whiteman, Donald E.↗
NASA NTRS2004

Complexity of life via collective mind

e mind is introduced as a set of simple intelligent units (say, neurons, or interacting agents), which can communicate by exchange of information without explicit global control. Incomplete information is compensated by a sequence of random guesses symmetrically distributed around expectations with prescribed variances. Both the expectations and variances are the invariants characterizing the whole class of agents. These invariants are stored as parameters of the collective mind, while they contribute into dynamical formalism of the agents' evolution, and in particular, into the reflective chains of their nested abstract images of the selves and non-selves. The proposed model consists of the system of stochastic differential equations in the Langevin form representing the motor dynamics, and the corresponding Fokker-Planck equation representing the mental dynamics (Motor dynamics describes the motion in physical space, while mental dynamics simulates the evolution of initial errors in terms of the probability density). The main departure of this model from Newtonian and statistical physics is due to a feedback from the mental to the motor dynamics which makes the Fokker-Planck equation nonlinear. Interpretation of this model from mathematical and physical viewpoints, as well as possible interpretation from biological, psychological, and social viewpoints are discussed. The model is illustrated by the dynamics of a dialog.

collective intelligence↗
NASA NTRS2010

Extreme Ultraviolet Variability Experiment (EVE) Multiple EUV Grating Spectrographs (MEGS): Radiometric Calibrations and Results

The NASA Solar Dynamics Observatory (SDO), scheduled for launch in early 2010, incorporates a suite of instruments including the Extreme Ultraviolet Variability Experiment (EVE). EVE has multiple instruments including the Multiple Extreme ultraviolet Grating Spectrographs (MEGS) A, B, and P instruments, the Solar Aspect Monitor (SAM), and the Extreme ultraviolet SpectroPhotometer (ESP). The radiometric calibration of EVE, necessary to convert the instrument counts to physical units, was performed at the National Institute of Standards and Technology (NIST) Synchrotron Ultraviolet Radiation Facility (SURF III) located in Gaithersburg, Maryland. This paper presents the results and derived accuracy of this radiometric calibration for the MEGS A, B, P, and SAM instruments, while the calibration of the ESP instrument is addressed by Didkovsky et al. . In addition, solar measurements that were taken on 14 April 2008, during the NASA 36.240 sounding-rocket flight, are shown for the prototype EVE instruments.

Hock, R. A.↗
NASA NTRS2013

Orion MPCV Touchdown Detection Threshold Development and Testing

A robust method of detecting Orion Multi ]Purpose Crew Vehicle (MPCV) splashdown is necessary to ensure crew and hardware safety during descent and after touchdown. The proposed method uses a triple redundant system to inhibit Reaction Control System (RCS) thruster firings, detach parachute risers from the vehicle, and transition to the post ]landing segment of the Flight Software (FSW). The vehicle crew is the prime input for touchdown detection, followed by an autonomous FSW algorithm, and finally a strictly time based backup timer. RCS thrusters must be inhibited before submersion in water to protect against possible damage due to firing these jets under water. In addition, neglecting to declare touchdown will not allow the vehicle to transition to post ]landing activities such as activating the Crew Module Up ]righting System (CMUS), resulting in possible loss of communication and difficult recovery. A previous AIAA paper gAssessment of an Automated Touchdown Detection Algorithm for the Orion Crew Module h concluded that a strictly Inertial Measurement Unit (IMU) based detection method using an acceleration spike algorithm had the highest safety margins and shortest detection times of other methods considered. That study utilized finite element simulations of vehicle splashdown, generated by LS ]DYNA, which were expanded to a larger set of results using a Kriging surface fit. The study also used the Decelerator Systems Simulation (DSS) to generate flight dynamics during vehicle descent under parachutes. Proto ]type IMU and FSW MATLAB models provided the basis for initial algorithm development and testing. This paper documents an in ]depth trade study, using the same dynamics data and MATLAB simulations as the earlier work, to further develop the acceleration detection method. By studying the combined effects of data rate, filtering on the rotational acceleration correction, data persistence limits and values of acceleration thresholds, an optimal configuration was determined. The lever arm calculation, which removes the centripetal acceleration caused by vehicle rotation, requires that the vehicle angular acceleration be derived from vehicle body rates, necessitating the addition of a 2nd order filter to smooth the data. It was determined that using 200 Hz data directly from the vehicle IMU outperforms the 40 Hz FSW data rate. Data persistence counter values and acceleration thresholds were balanced in order to meet desired safety and performance. The algorithm proved to exhibit ample safety margin against early detection while under parachutes, and adequate performance upon vehicle splashdown. Fall times from algorithm initiation were also studied, and a backup timer length was chosen to provide a large safety margin, yet still trigger detection before CMUS inflation. This timer serves as a backup to the primary acceleration detection method. Additionally, these parameters were tested for safety on actual flight test data, demonstrating expected safety margins.

Daum, Jared↗
NASA NTRS1994

Ethylene dynamics in the CELSS biomass production chamber

A material balance model for ethylene was developed and applied retrospectively to data obtained in the Biomass Production Chamber of CELSS in order to calculate true plant production rates of ethylene. Four crops were analyzed: wheat, lettuce, soybean, and potato. The model represents an effort to account for each and every source and sink for ethylene in the system. The major source of ethylene is the plant biomass and the major sink is leakage to the surroundings. The result, expressed in the units of ppd/day, were converted to nl of ethylene per gram of plant dry mass per hour and compare favorably with recent glasshouse to belljar experiments.

Rakow, Allen L.↗
NASA NTRS1975

A General Simulator Using State Estimation for a Space Tug Navigation System

A general simulation program is presented (GSP) involving nonlinear state estimation for space vehicle flight navigation systems. A complete explanation of the iterative guidance mode guidance law, derivation of the dynamics, coordinate frames, and state estimation routines are given so as to fully clarify the assumptions and approximations involved so that simulation results can be placed in their proper perspective. A complete set of computer acronyms and their definitions as well as explanations of the subroutines used in the GSP simulator are included. To facilitate input/output, a complete set of compatable numbers, with units, are included to aid in data development. Format specifications, output data phrase meanings and purposes, and computer card data input are clearly spelled out. A large number of simulation and analytical studies were used to determine the validity of the simulator itself as well as various data runs.

Boland, J. S., III↗
NASA NTRS1988

Aerodynamic flow quality and acoustic characteristics of the 40- by 80-foot test section circuit of the National Full-Scale Aerodynamic Complex

The 40- by 80-foot wind tunnel circuit of the National Full-Scale Aerodynamic Complex (NFAC) has recently undergone major modifications and subsequently completed final acceptance testing. The initial testing and calibration of the wind tunnel are described and in many cases these results are compared with predictions derived from model tests and theoretical analyses. The wind tunnel meets or exceeds essentially all performance objectives. The facility runs smoothly and routinely at its maximum test-section velocity of 300 knots (Mach number = 0.45). An effective cooling air exchange system enables the wind tunnel to operate indefinitely at this maximum power condition. Throughout the operating envelope of the wind tunnel the test-section dynamic pressure is uniform to within + or - 0.5 deg, and the axial component of turbulence is generally less than 0.5 percent. Acoustic measurements indicate that, due to the low noise fans and acoustic treatment in the wind-tunnel circuit and test section, the background noise level in the test section is comparable to other large-scale acoustic wind tunnels in the United States and abroad.

Olson, Lawrence E.↗
NASA NTRS1999

Aerodynamic Flow Field Measurements for Automotive Systems

The design of a modern automotive air handling system is a complex task. The system is required to bring the interior of the vehicle to a comfortable level in as short a time as possible. A goal of the automotive industry is to predict the interior climate of an automobile using advanced computational fluid dynamic (CFD) methods. The development of these advanced prediction tools will enable better selection of engine and accessory components. The goal of this investigation was to predict methods used by the automotive industry. To accomplish this task three separate experiments were performed. The first was a laboratory setup where laser velocimeter (LV) flow field measurements were made in the heating and air conditioning unit of a Ford Windstar. The second involved flow field measurements in the engine compartment of a Ford Explorer, with the engine running idle. The third mapped the flow field exiting the center dashboard panel vent inside the Explorer, while the circulating fan operated at 14 volts. All three experiments utilized full-coincidence three-component LV systems. This enabled the mean and fluctuating velocities to be measured along with the Reynolds stress terms.

Hepner, Timothy E.↗
NASA NTRS1996

Cascade Error Projection: A Learning Algorithm for Hardware Implementation

In this paper, we workout a detailed mathematical analysis for a new learning algorithm termed Cascade Error Projection (CEP) and a general learning frame work. This frame work can be used to obtain the cascade correlation learning algorithm by choosing a particular set of parameters. Furthermore, CEP learning algorithm is operated only on one layer, whereas the other set of weights can be calculated deterministically. In association with the dynamical stepsize change concept to convert the weight update from infinite space into a finite space, the relation between the current stepsize and the previous energy level is also given and the estimation procedure for optimal stepsize is used for validation of our proposed technique. The weight values of zero are used for starting the learning for every layer, and a single hidden unit is applied instead of using a pool of candidate hidden units similar to cascade correlation scheme. Therefore, simplicity in hardware implementation is also obtained. Furthermore, this analysis allows us to select from other methods (such as the conjugate gradient descent or the Newton's second order) one of which will be a good candidate for the learning technique. The choice of learning technique depends on the constraints of the problem (e.g., speed, performance, and hardware implementation); one technique may be more suitable than others. Moreover, for a discrete weight space, the theoretical analysis presents the capability of learning with limited weight quantization. Finally, 5- to 8-bit parity and chaotic time series prediction problems are investigated; the simulation results demonstrate that 4-bit or more weight quantization is sufficient for learning neural network using CEP. In addition, it is demonstrated that this technique is able to compensate for less bit weight resolution by incorporating additional hidden units. However, generation result may suffer somewhat with lower bit weight quantization.

Duong, Tuan A.↗
NASA NTRS2005

Virtual Observatories for Space Physics Observations and Simulations: New Routes to Efficient Access and Visualization

New tools for data access and visualization promise to make the analysis of space plasma data both more efficient and more powerful, especially for answering questions about the global structure and dynamics of the Sun-Earth system. We will show how new existing tools (particularly the Virtual Space Physics Observatory-VSPO-and the Visual System for Browsing, Analysis and Retrieval of Data-ViSBARD; look for the acronyms in Google) already provide rapid access to such information as spacecraft orbits, browse plots, and detailed data, as well as visualizations that can quickly unite our view of multispacecraft observations. We will show movies illustrating multispacecraft observations of the solar wind and magnetosphere during a magnetic storm, and of simulations of 3 0-spacecraft observations derived from MHD simulations of the magnetosphere sampled along likely trajectories of the spacecraft for the MagCon mission. An important issue remaining to be solved is how best to integrate simulation data and services into the Virtual Observatory environment, and this talk will hopefully stimulate further discussion along these lines.

Roberts, Aaron↗
NASA NTRS2009

Development of a Portable Oxygen Monitoring System for Operations in the International Space Station Airlock

NASA is currently engaged in an activity to facilitate effective operations on the International Space Station (ISS) after the Space Shuttle retires. Currently, the Space Shuttle delivers crew and cargo to and from ISS. The Space Shuttle provides the only large scale method of hardware return from ISS to the ground. Hardware that needs to be periodically repaired, refurbished, or recalibrated must come back from ISS on the Shuttle. One example of NASA flight hardware that is used on ISS and refurbished on the ground is the Compound Specific Analyzer for Oxygen (CSA-O2). The CSA-O2 is an electrochemical sensor that is used on orbit for about 12 months (depending on Shuttle launch schedules), then returned to the ground for sensor replacement. The shuttle is scheduled to retire in 2010, and the ISS is scheduled to operate until 2016. NASA needs a hand held sensor that measures oxygen in the ISS environment and has a 5-10 year service life. After conducting a survey of oxygen sensor systems, NASA selected a Tunable Diode Laser Absorption Spectrometer (TDLAS) as the method of measurement that best addresses the needs for ISS. These systems are compact, meet ISS accuracy requirements, and because they use spectroscopic techniques, the sensors are not consumed or altered after making a measurement. TDLAS systems have service life ratings of 5-10 years, based on the lifetime of the laser. NASA is engaged in modifying a commercially available sensor, the Vaisala OMT 355, for the ISS application. The Vaisala OMT 355 requires three significant modifications to meet ISS needs. The commercial sensor uses a wall mount power supply, and the ISS sensor needs to use a rechargeable battery as its source of power. The commercial sensor has a pressure correction setpoint: the sensor can be adjusted to operate at reduced pressure conditions, but the sensor does not self correct dynamically and automatically. The ISS sensor needs to operate in the airlock, and make accurate measurements in an environment that can change from 14.7 psia to 10.2 psia in 15 minutes. The commercial sensor needs to be repackaged into a configuration that is more compact, and better suited for ISS airlock operations. NASA has recently completed a prototype of the reconfigured system. The unit has been repackaged in a way that the optical path of the spectrometer is unchanged, but the electronics has been integrated into a case measuring 10.7 X 7.2 X 3.0 inches. Two flight qualified rechargeable batteries have been integrated into system. The batteries can power the sensor for 10 hours on a single charge. A pressure sensor has been added to the system. The modified unit automatically compensates for changes in pressure, and meets 0.2% accuracy requirements for oxygen measurements in an environment with 18 to 32% oxygen across a pressure range of 10.0 to 15.0 psia.

Graf, John↗
NASA NTRS2010

Tracking Data Certification for the Lunar Reconnaissance Orbiter

This paper details the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF) tracking data certification effort of the Lunar Reconnaissance Orbiter (LRO) Space Communications Network (SCN) complement of tracking stations consisting of the NASA White Sands 1 antenna (WS1), and the commercial provider Universal Space Network (USN) antennas at South Point, Hawaii; Dongara Australia; Weilheim, Germany; and Kiruna, Sweden. Certification assessment required the cooperation and coordination of parties not under the control of either the LRO project or ground stations as uplinks on cooperating spacecraft were necessary. The LRO range-tracking requirement of 10m 1 sigma could be satisfactorily demonstrated using any typical spacecraft capable of range tracking. Though typical Low Earth Orbiting (LEO) or Geosynchronous Earth Orbiting (GEO) spacecraft may be adequate for range certification, their measurement dynamics and noise would be unacceptable for proper Doppler certification of 1-3mm/sec 1 sigma. As LRO will orbit the Moon, it was imperative that a suitable target spacecraft be utilized which can closely mimic the expected lunar orbital Doppler dynamics of +/-1.6km/sec and +/-1.5m/sq sec to +/-0.15m/sq sec, is in view of the ground stations, supports coherent S-Band Doppler tracking measurements, and can be modeled by the FDF. In order to meet the LRO metric tracking data specifications, the SCN ground stations employed previously uncertified numerically controlled tracking receivers. Initial certification testing revealed certain characteristics of the units that required resolution before being granted certification.

Morinelli, Patrick J.↗
NASA NTRS2002

Experimental Replication of Relict "Dusty" Olivine in Type 1B Chondrules

Introduction: Relict "dusty" olivine is considered to be a remnants of previous chondrule forming events based on petrographic and chemical evidence. Dynamic crystallization experiments confirm that dusty olivine can be produced by reduction of FeO-rich olivine in Unequilibrated Ordinary Chondrite (UOC) material. The results of these experiments compliment those of who also produced dusty olivine, but from synthetic starting materials. Techniques: Dynamic crystallization experiments were conducted in which UOC material was reduced in presence of graphite. Starting material was coarsely ground GR095554 or WSG95300 that contained olivine of Fo 65-98. Approximately 75 mg. of UOC material was placed in a graphite crucible and sealed in an evacuated silica tube. The tube was suspended in a gas-mixing furnace operated at 1 log unit below the IW buffer. The experiments were as brief as 1.5 hrs up to 121 hrs. Results: Dusty olivine was produced readily in experiments melted at 1400 C for I hr. and cooled between 5 and 100 C/hr or melted at 1300-1400 C for 24 hours. Fe-rich olivine (dusty olivine precursors) that have been partially reduced were common in the experiments melted at 1400 C and cooled at 1000 C/hr or melted at 1200 C for 24 hrs. Relict olivine is absent in experiments melted at 1400 for 24 hrs, melted above 1400 C, or cooled more slowly than 10 C/hr. Relict olivine in the experiments has minimum Fo value of 83 . Thus even in the shortest experiments the most Fe-rich olivine has been altered significantly. The precursor olivine disappears in a few to many hours depending on temperature. The experiments show Fe-rich olivine in all stages of transition to the new dusty form. The olivine is reduced to form dusty olivine in a matter of a few hours at temperatures less than 1400 C and in minutes at higher temperatures. The reduction appears to proceed from the rim of the crystal inward with time. The reduction appears initially rectilinear as if controlled by crystallography, but with time Fe-metal blebs are randomly distributed throughout the olivine. In a given experiment, dusty olivine can be found in varying stages of development, but in the longest experiments, the Fe-metal blebs are dominant and they appear to be migrating out of the olivine. The composition of the dusty olivine ranges from Fo 94-99. The Cr, Mn, and Ca content of the newly formed, dusty olivine is slightly less on average that the precursor olivine, but is till with the range of type 1 olivine. Chadacrysts in the low Ca pyroxene are most common in the higher temperature, more slowly cooled experiments and range in composition from Fo 90-99. Application to chondrule formation: These experiments place time-temperature limits on the preservation of Fe-rich olivine and the production of dusty olivine during chondrule forming events. The reduction process proceeds in a few hours at temperatures above 1400 C and in 10's of hours at temperature between 1200 and 1300 C. This result further confirms th at chondrules form in a few hours to days as suggested earlier. The experiments also confirm that dusty olivine can form from typical Fe-rich olivine in UOC material during the recycling of such olivine in the chondrule forming process.

Lofgren, Gary E.↗
NASA NTRS2020

Toward Transition Modeling in a Hypersonic Boundary Layer at Flight Conditions

An accurate physics-based transition prediction method integrated with computational fluid dynamics (CFD) solvers is pursued for hypersonic boundary layer flows over slender hypersonic vehicles at flight conditions. The geometry and flow conditions are selected to match relevant trajectory locations from the ascent phase of the HIFiRE-1 flight experiment, namely, a 7-degree half-angle cone with 2.5 mm nose radius, freestream Mach numbers in the range of 3.8 – 5.5 and freestream unit Reynolds numbers in the range of 3.3 × 10(exp 6) – 21.4 × 10(exp 6) m(exp -1). Earlier research had shown that the onset of transition during the HIFiRE-1 flight experiment correlated with an amplification factor of N ≈ 13.5 for the planar Mack modes. However, to incorporate the N-factor correlations into a CFD code, we investigate surrogate models for disturbance amplification that avoid the direct computation of stability characteristics. A commonly used approach for low-speed flows is based on an a priori database of stability characteristics for locally similar profiles. However, the results presented in this paper demonstrate that the application of this approach to hypersonic boundary layers over blunt spherical nose-tip cones leads to large, unacceptable errors in the predictions of amplification factors, mainly due to its failure in accounting for the effects of the entropy layer on the boundary-layer profiles along the length of the model. We propose and demonstrate an alternate approach that employs the stability computations for a canonical set of blunt cone configurations to train a physics-informed convolutional neural network model that is shown to provide substantially improved transition predictions for hypersonic flow configurations with entropy-layer effects. Furthermore, the excellent performance of the neural network model is also confirmed for cone configurations with nose radius and half-angle values that do not correspond to those used to build the database. Finally, the convolutional neural network model is shown to outperform the linear stability calculations for underresolved basic states.

Pedro Paredes↗
NASA NTRS2020

Striped Mullet Migration Patterns in the Indian River Lagoon: A Network Analysis Approach to Spatial Fisheries Management

Striped mullet (Mugil cephalus) are numerically abundant forage fish, highly valuable as prey and commercially valuable to humans. From September to December, mullet in the Indian River Lagoon (IRL), Florida undergo an annual migration from inshore foraging habitats to oceanic spawning sites. However, their migratory pathways, in particular their intra-estuarine movement pathways, remain unknown. To address this knowledge gap, we utilized passive acoustic telemetry to assess the movement patterns of M. cephalus within the IRL. Thirty-two fish were tagged, generating usable tracks from 18 individuals. The mean (±s.d.) time that fish were detected in the array was ~38 ± 90 days, with the longest at 444 days. We also document the first evidence of skipped spawning in M. cephalus inhabiting waters of the southeastern United States. These data suggest impoundments around the Merritt Island National Wildlife Refuge appear to serve as important refugia for striped mullet while the Banana and Indian Rivers act as corridors during their inshore migratory movements. Through spatial fisheries management, high value habitat and connective elements utilized by mullet and other vital forage fish may be identified, to benefit both natural and human dynamics in estuarine systems.

Acoustic telemetry↗