Science.gov

Sample records for magnetometer towed array

  1. Adaption of the Magnetometer Towed Array geophysical system to meet Department of Energy needs for hazardous waste site characterization

    SciTech Connect

    Cochran, J.R.; McDonald, J.R.; Russell, R.J.; Robertson, R.; Hensel, E.

    1995-10-01

    This report documents US Department of Energy (DOE)-funded activities that have adapted the US Navy`s Surface Towed Ordnance Locator System (STOLS) to meet DOE needs for a ``... better, faster, safer and cheaper ...`` system for characterizing inactive hazardous waste sites. These activities were undertaken by Sandia National Laboratories (Sandia), the Naval Research Laboratory, Geo-Centers Inc., New Mexico State University and others under the title of the Magnetometer Towed Array (MTA).

  2. Simultaneous Magnetometer and EM61 MK2 Vehicle-Towed Array for Wide Area Assessment

    DTIC Science & Technology

    2008-09-01

    years old whereas other portions were only designed to survive a single 2002 APG fielding, the system is best operated by its inventors . Through...check, cleaning air filters, and greasing the axles of the tow platform. Major unforeseen problems included persistent jamming of our GPS base-to-radio...coils are deployed on their native wheels ). Although the system is capable of using EM61 upper coils and employing the “D” setting on the electronics

  3. Optical magnetometer array for fetal magnetocardiography

    NASA Astrophysics Data System (ADS)

    Wyllie, Robert; Kauer, Matthew; Wakai, Ronald T.; Walker, Thad G.

    2012-06-01

    We describe an array of spin-exchange relaxation free optical magnetometers designed for detection of fetal magnetocardiography (fMCG) signals. The individual magnetometers are configured with a small volume with intense optical pumping, surrounded by a large pump-free region. Spin-polarized atoms that diffuse out of the optical pumping region precess in the ambient magnetic field and are detected by a probe laser. Four such magnetometers, at the corners of a 7 cm square, are configured for gradiometry by feeding back the output of one magnetometer to a field coil to null uniform magnetic field noise at frequencies up to 200 Hz. Using this array, we present the first measurements of fMCG signals using an atomic magnetometer.

  4. Optical magnetometer array for fetal magnetocardiography

    PubMed Central

    Wyllie, Robert; Kauer, Matthew; Wakai, Ronald T.; Walker, Thad G.

    2012-01-01

    We describe an array of spin-exchange-relaxation-free optical magnetometers designed for detection of fetal magnetocardiography (fMCG). The individual magnetometers are configured with a small volume with intense optical pumping, surrounded by a large pump-free region. Spin-polarized atoms that diffuse out of the optical pumping region precess in the ambient magnetic field and are detected by a probe laser. Four such magnetometers, at the corners of a 7 cm square, are configured for gradiometry by feeding back the output of one magnetometer to a field coil to null uniform magnetic field noise at frequencies up to 200 Hz. We present the first measurements of fMCG signals using an atomic magnetometer. PMID:22739870

  5. Optical magnetometer array for fetal magnetocardiography.

    PubMed

    Wyllie, Robert; Kauer, Matthew; Wakai, Ronald T; Walker, Thad G

    2012-06-15

    We describe an array of spin-exchange-relaxation-free optical magnetometers designed for detection of fetal magnetocardiography (fMCG). The individual magnetometers are configured with a small volume with intense optical pumping, surrounded by a large pump-free region. Spin-polarized atoms that diffuse out of the optical pumping region precess in the ambient magnetic field and are detected by a probe laser. Four such magnetometers, at the corners of a 7 cm square, are configured for gradiometry by feeding back the output of one magnetometer to a field coil to null uniform magnetic field noise at frequencies up to 200 Hz. We present the first measurements of fMCG signals using an atomic magnetometer.

  6. Fat-Line Towed-Array Force Measurement Apparatus

    DTIC Science & Technology

    2000-06-12

    No. 78872 n 3 FAT -LINE TOWED-ARRAY FORCE MEASUREMENT APPARATUS 4 5 STATEMENT OF GOVERNMENT INTEREST 6 The invention described herein may be...application. 16 17 BACKGROUND OF THE INVENTION 18 (1) Field of the Invention 19 The present invention relates generally to fat -line towed- 2 0 arrays, and...more particularly to an apparatus for measuring the 21 force applied to fat -line towed-arrays during flushing cycles. 22 (2) Description of the

  7. Fetal Magnetocardiography with an Atomic Magnetometer Array

    NASA Astrophysics Data System (ADS)

    Sulai, Ibrahim; Deland, Zack; Wahl, Colin; Wakai, Ronald; Walker, Thad

    2014-05-01

    Fetal magnetocardiography (fMCG) is a powerful technique for analyzing the heartbeat patterns of inutero fetuses. We present results from our array of four Spin-Exchange Relaxation-Free (SERF) rubidium-87 atomic magnetometers which has been used to detect and create these magnetocardiograms. We have demonstrated a magnetic noise sensitivity of < 10 fT /√{ Hz} , limited by the Johnson noise of the magnetically-shielded room. We discuss new design features and experimental practices that have increased our sensitivity and allowed us to successfully measure an fMCG at a gestational age of only 21 weeks. We hope to eventually apply these techniques to the detection and diagnosis of heartbeat arrhythmias, which, if detected early enough, can be treated inutero . This work is supported by the National Institutes of Health.

  8. Fetal MCG with Atomic Magnetometer Array

    NASA Astrophysics Data System (ADS)

    Deland, Zack; Bulatowicz, Michael D.; Sulai, Ibrahim A.; Wahl, Colin P.; Wakai, Ronald T.; Walker, Thad G.

    2016-05-01

    We present results on the development of 87Rb atomic magnetometers for the detection of a fetal magnetocardiogram (fMCG). Operating in the spin-exchange relaxation free (SERF) regime, the magnetometers' sensitivities are reported at the 1 fT /√{ Hz } level. Environmental common-mode noise, including the field from the maternal heart, can be suppressed by operating the magnetometers in a gradiometric configuration. We report on schemes from implementing such gradiometers along with recent fMCG measurements. This work is supported by the National Institutes of Health.

  9. A full optically operated magnetometer array: an experimental study.

    PubMed

    Ijsselsteijn, R; Kielpinski, M; Woetzel, S; Scholtes, T; Kessler, E; Stolz, R; Schultze, V; Meyer, H-G

    2012-11-01

    We show the operation of an optically pumped magnetometer array in a 50 μT magnetic field. The various components for a fully optical and non-magnetic detector unit were constructed and evaluated, from which a prototype unit was assembled with fiber coupled electronics. In this unit the magnetometers were operated using the intensity modulated method and heated with an off-resonant laser. Calculations on the temperature distribution were used to design the magnetometer array. Different magnetometers in such a detector unit were characterized and showed identical performance. Without applying noise reduction schemes, the obtained magnetic field resolution is a factor 2.5 above the shot noise level down to frequencies of about 7 Hz.

  10. A Phased Array Magnetometer for Sensing IED

    DTIC Science & Technology

    2008-02-04

    of information is estimated to average 1 tiour per response, including the time for reviewing instructions, searching existing data sources, gathering...Device Organization (JIEDDO) (Contract No: FA9550-07- 1 -0107) Program Dr. Byung-Lip "Les" Lee Manager Project Title A Phased Array...Los Angeles, CA 90095-1597 Voice: 310-825-6030 Fax:310-206-2302 1 . OVERALL OBJECTIVE The objective of this project was to develop the fundamental

  11. A Method to Estimate Local Towed Array Angles Using Flush Mounted Hot Film Wall Shear Sensors

    DTIC Science & Technology

    2008-06-05

    during turns. In the invention, a flush mounted hot film sensor and an anemometry system are used to measure the mean and fluctuating turbulent wall...decrease in towing speed necessitated by certain maneuvers can cause the towed array to fall or sink. Suitable flush mounted hot film sensors and anemometry ...the calculated shaped of the deployed towed array 100 and the physical restraints of incorporating the hot -film sensors 108 and associated wiring into

  12. Eigenvalues of the sample covariance matrix for a towed array.

    PubMed

    Gerstoft, Peter; Menon, Ravishankar; Hodgkiss, William S; Mecklenbräuker, Christoph F

    2012-10-01

    It is well known that observations of the spatial sample covariance matrix (SCM, also called the cross-spectral matrix) reveal that the ordered noise eigenvalues of the SCM decay steadily, but common models predict equal noise eigenvalues. Random matrix theory (RMT) is used to derive and discuss properties of the eigenvalue spectrum of the data SCM for linear arrays, with an application to ocean acoustic data. Noise on the array is considered either incoherent or propagating acoustic noise that is coherent across the array. Using conventional three-dimensional or two-dimensional isotropic noise models with full or snapshot-deficient observations, realizations of the SCM eigenvalues are explained using RMT. Deep-water towed-array data are analyzed and it is shown that the eigenvalues of the SCM compare well with theory. It is demonstrated how RMT can be applied to study eigenvalue spectrum estimation as dependent on array properties (element spacing to wavelength ratio) and data sampling (snapshots). Apart from explaining the observed noise eigenvalue spectrum, the improved model of the eigenvalue spectrum has important applications in array signal processing.

  13. Magnetic mapping of submarine hydrothermal systems at Marsili and Palinuro volcanoes from deep-towed magnetometer data

    NASA Astrophysics Data System (ADS)

    Caratori Tontini, F.; Bortoluzzi, G.; Carmisciano, C.; Cocchi, L.; de Ronde, C. E.; Ligi, M.; Muccini, F.

    2013-12-01

    We collected near-bottom magnetic data at Marsili and Palinuro volcanoes in the Southern Tyrrhenian Sea, by adding a magnetometer to a deep-towed sidescan sonar. Equivalent magnetization maps obtained by inversion of the recorded magnetic anomalies are analyzed to map alteration zones related to hydrothermal processes and are correlated with water-column and seafloor observations of hydrothermal activity. At Marsili volcano, we found a large elliptical area of low magnetization, confirming the existence of a large hydrothermal system located in proximity of the top cone, above the magma chamber. Palinuro volcano is characterized by hydrothermal venting located along the caldera walls, where the corresponding ring faults may provide preferred pathways for the upflow of the hydrothermal fluids.

  14. Dynamic Towed Array Models and State Estimation for Underwater Target Tracking

    DTIC Science & Technology

    2013-09-01

    19, 2013. [6] S. G. Lemon , “Towed-array history, 1917–2003,” IEEE J. of Ocean. Eng., vol. 29, pp. 365–373, Apr. 2004. [7] M. S. Cohen and R. V...and S. G. Lemon , “Recent progress in towed hydrophone array research,” IEEE J. of Ocean. Eng., vol. 29, pp. 374–387, Apr. 2004. [10] B. L. Scala

  15. Real-time threat detection using magnetometer arrays

    NASA Astrophysics Data System (ADS)

    Prouty, Mark D.; Tchernychev, Mikhail

    2016-05-01

    In this paper we present a discussion of using an array of atomic magnetometers to locate the presence of ferrous materials, such as concealed weapons, in real time. Ferrous materials create magnetic field anomalies. In order to determine the location of such objects, readings from many positions must be analyzed. This field inversion is typically done in post processing, once readings over a survey area or region of interest have been gathered. With the recent development of small and low power sensors, the dozen or so sensors required to provide information for magnetic field inversion may be deployed. We have built such an array and present here the results of using a realtime inversion algorithm. The inversion algorithm accurately determines target properties at a rate of 10 times per second as objects move past the array. Accuracies are as good as those obtained with target inversion methods used in analyzing data for unexploded ordnance detection. While those methods are typically applied in post processing, we show here those methods work even better when applied in real-time. We further present some analyses of the predicted performance of arrays in various geometries to address issues in security, such as crowd or perimeter monitoring. Target inversion methods may be accurately simulated, allowing for the development and testing of algorithms in an efficient manner. Additional processing may be done using the time history of the inversion results to remove false alarms and enhance detection. The key step is to start with an inversion method, utilizing the mathematical properties of magnetic fields and the known geometry of the measurements.

  16. MAGNETOMETER

    DOEpatents

    Leavitt, M.A.

    1958-11-18

    A magnetometer ls described, partlcularly to a device which accurately indicates the polarity and intensity of a magnetlc field. The main feature of the invention is a unique probe construction in combinatlon wlth a magnetic fleld detector system. The probe comprises two coils connected in series opposition for energization with an a-c voltage. The voltage lnduced in a third coll on the probe, a pick-up coil, is distorted by the presence of an external field to produce even harmonic voltages. A controlled d-c current is passed through the energized coils to counter the dlstortlon and reduce tbe even harmonic content to a null. When the null point is reached, the d-c current is a measure of the external magnetic field strength, and the phase of the pickup coil voltage indicates tbe field polarlty.

  17. Magnetocardiography with a modular spin-exchange relaxation-free atomic magnetometer array

    NASA Astrophysics Data System (ADS)

    Wyllie, R.; Kauer, M.; Smetana, G. S.; Wakai, R. T.; Walker, T. G.

    2012-05-01

    We present a portable four-channel atomic magnetometer array operating in the spin-exchange relaxation-free regime. The magnetometer array has several design features intended to maximize its suitability for biomagnetic measurement, specifically foetal magnetocardiography, such as a compact modular design and fibre-coupled lasers. The modular design allows the independent positioning and orientation of each magnetometer. Using this array in a magnetically shielded room, we acquire adult magnetocadiograms. These measurements were taken with a 6-11 fT Hz-1/2 single-channel baseline sensitivity that is consistent with the independently measured noise level of the magnetically shielded room.

  18. Magnetocardiography with a modular spin-exchange relaxation-free atomic magnetometer array.

    PubMed

    Wyllie, R; Kauer, M; Smetana, G S; Wakai, R T; Walker, T G

    2012-05-07

    We present a portable four-channel atomic magnetometer array operating in the spin-exchange relaxation-free regime. The magnetometer array has several design features intended to maximize its suitability for biomagnetic measurement, specifically foetal magnetocardiography, such as a compact modular design and fibre-coupled lasers. The modular design allows the independent positioning and orientation of each magnetometer. Using this array in a magnetically shielded room, we acquire adult magnetocadiograms. These measurements were taken with a 6-11 fT Hz(-1/2) single-channel baseline sensitivity that is consistent with the independently measured noise level of the magnetically shielded room.

  19. 77 FR 52317 - Record of Decision for Surveillance Towed Array Sensor System Low Frequency Active Sonar

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-29

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF DEFENSE Department of the Navy Record of Decision for Surveillance Towed Array Sensor System Low Frequency Active... Array Sensor System Low Frequency Active (SURTASS LFA) sonar systems with certain...

  20. Tracking sperm whale (Physeter macrocephalus) dive profiles using a towed passive acoustic array

    NASA Astrophysics Data System (ADS)

    Thode, Aaron

    2004-07-01

    A passive acoustic method is presented for tracking sperm whale dive profiles, using two or three hydrophones deployed as either a vertical or large-aperture towed array. The relative arrival times between the direct and surface-reflected acoustic paths are used to obtain the ranges and depths of animals with respect to the array, provided that the hydrophone depths are independently measured. Besides reducing the number of hydrophones required, exploiting surface reflections simplifies automation of the data processing. Experimental results are shown from 2002 and 2003 cruises in the Gulf of Mexico for two different towed array deployments. The 2002 deployment consisted of two short-aperture towed arrays separated by 170 m, while the 2003 deployment placed an autonomous acoustic recorder in tandem with a short-aperture towed array, and used ship noise to time-align the acoustic data. The resulting dive profiles were independently checked using single-hydrophone localizations, whenever multipath reflections from the ocean bottom could be exploited to effectively create a large-aperture vertical array. This technique may have applications for basic research and for real-time mitigation for seismic airgun surveys.

  1. The dynamic research and position estimation of the towed array during the U-turn process

    NASA Astrophysics Data System (ADS)

    Yang, J. X.; Shuai, C. G.; He, L.; Zhang, S. K.; Zhou, S. T.

    2016-09-01

    A dynamic model for estimating position of ship towed array during U-turn manoeuvre is introduced and developed. Based on this model, the influences of the parameters such as time step and segment length on the numerical simulation are analysed. The results indicate that decreasing the time step has little effect on the simulation accuracy but will increase the computational time. The selection of segment length has a great influence on the estimation of ship towed array position during U-turn manoeuvre. Reducing the segment length somewhat increases the computational complexity and significantly improves simulation precision.

  2. Calibration and Thermal Analysis of a Conformal SERF Magnetometer Array for MEG Applications

    NASA Astrophysics Data System (ADS)

    Alexander, Elizabeth V.

    In magnetoencephalography (MEG), a measurement of the magnetic field produced by the brain, it is critical for the distance between the magnetometers and the brain to be small and unchanging. Limitations of SQUIDs, the magnetometers used in most MEG systems, make this requirement difficult to meet. SERF magnetometers have been proposed as an alternative technology for use in more portable and flexible MEG systems. This research considers two of the challenges associated with an array of SERF magnetometers attached to a conformal cap. First, for meaningful measurements in MEG, it is important for the locations and orientations of magnetometers to be known. This information can be estimated using the magnetometers' measurements of a known magnetic field produced by a configuration of magnetic dipoles, but the estimation algorithm is extremely sensitive to the dipole configuration. This thesis introduces a graphical tool to assess the quality of a configuration of magnetic dipoles. Second, the core of SERF magnetometers has a high operating temperature. This work finds a thermal insulation layout that allows for a small overall magnetometer package size while maintaining proper operation temperature and preventing thermal injury to a patient.

  3. Superconducting gradiometer-magnetometer array for magnetotelluric logging

    SciTech Connect

    Vozoff, K.

    1982-09-14

    A subsurface electromagnetic sensing device for use in boreholes and mine shafts which includes a sonde for lowering underground which is supercooled and contains squid gradiometers for measuring vector current density, and magnetometers for measuring vector magnetic fields. When these measured values are combined, information is obtained to construct a conductivity model of the underlying and surrounding subsurface region.

  4. The development of a multichannel atomic magnetometer array for fetal magnetocardiography

    NASA Astrophysics Data System (ADS)

    Wylie, Robert, IV

    Biomagnetic signals can provide important information about electrical processes in the human body. Because of the small signal sizes, magnetic detection is generally used where other detection methods are incomplete or insufficiently sensitive. One important example is fetal magnetocardiography (fMCG), where the detection of magnetic signals is currently the only available technique for certain clinical applications, such as the detection of cardiac arrhythmia. Until now, magnetometers based on superconducting quantum interference devices (SQUIDs), which can operate at sensitivities down to 1 fT Hz-1/2 have been the only option. The low Tc superconductors and associated cryogenics required for the most sensitive devices has led to interest in alternative technologies. In the last decade, atomic magnetometers operating in the spin-exchange relaxation-free (SERF) regime have demonstrated a higher sensitivity than SQUIDs while operating near room temperature. Though large SERF magnetometer arrays have not yet been built, smaller arrays should be sufficient for applications such as fMCG. In this thesis, we present the design and characterization of a portable four-channel SERF atomic magnetometer array with a 5-10 fT Hz-1/2 single channel baseline sensitivity. The magnetometer array has several design features intended to maximize its suitability for biomagnetic measurement, specifically fMCG, such as a compact modular design and large, flexible channel spacing from 5-15 cm. The modular design allows for easily adding units to the array and the independent positioning and orientation of each magnetometer, in principle allowing for non-planar array geometries. Using this array in a magnetically shielded room, we acquire adult magnetocadiograms and, for the first time with a SERF magnetometer, fMCG. We also investigate the use of different operational modes of the magnetometer to extend its functionality, specifically modulation methods for additional directional

  5. DOA estimation based on multiple beamspace measurements sparse reconstruction for manoeuvring towed array

    NASA Astrophysics Data System (ADS)

    Yuan, J.; Xiao, H.; Cai, Z. M.; Xi, C.

    2017-01-01

    The port-starboard ambiguity in the conventional single towed linear array sonar is one of the most deceiving obstacles which exist in the way of development of spatial spectrum estimation. In order to improve the performance of target detection and Direction of Arrival (DOA) estimation, this paper proposes a novel spatial spectrum sparse reconstruction method based on multiple beamspace measurements (MBM-SR). An array sparse signal model for manoeuvring towed array is established. Then the Mutual Incoherent Property (MIP) is analyzed to ensure the proposed algorithm possessing better spatial spectrum reconstruction property. Simulation results demonstrate that, compared with Conventional Beam Forming (CBF) algorithm, the proposed algorithm has evident advantage in ambiguity suppression ratio (ASR) and estimation performance.

  6. Hydrates in the California Borderlands: 2D CSEM inversion results from towed and seafloor arrays

    NASA Astrophysics Data System (ADS)

    Kannberg, P. K.; Constable, S.; Key, K.

    2013-12-01

    Methane hydrate, an ice-like solid clathrate of methane and water, forms in shallow continental slope sediments, and is both a potential energy source and geologic hazard. Traditionally, methane hydrate presence is inferred from a seismically detected bathymetry tracking velocity inversion, known as the bottom-simulating reflector (BSR). However the BSR is an indicator of free gas at the base of the hydrate stability zone, and not an indicator of hydrate. As such, seismic methods are limited in their capacity to identify and quantify hydrate presence and concentration. Controlled source electromagnetic (CSEM) methods are sensitive to, and are able to directly detect, the presence of electrically resistive methane hydrate and free gas. Additionally, because shallow resistors can mimic deeper resistors in seafloor instruments, understanding the shallow sediment structure can inform deeper crustal modeling. We conducted two CSEM surveys in the San Nicolas Basin, located 150km west of San Diego where a BSR was identified from legacy seismics. Both surveys were conducted using a deep-towed EM transmitter followed by 4 towed 3-axis electric field receivers spaced every 200 m from 400-1000 m behind the transmitter. Either a half-hertz or quarter-hertz modified square wave was transmitted on a 200 ampere, 100 m dipole that was flown between 50 and 100m above the seafloor. The short transmitter-receiver offset allows resolution of shallow structure (less than 1km below seafloor), while the longer transmitter-seafloor receiver resolves deeper structure. Between the two surveys, 27 seafloor receivers were deployed and ~150km of lines were towed, including 5 transects of the basin coincident with legacy seismic lines, and a short-offset repeatability study. Initial 1D modeling showed the presence of a resistor coincident with the BSR. Further 2D inversions using the MARE2DEM inversion program were run for the towed array. These inversions show a 4 ohm-m resistor in the central

  7. An efficient method for tracking a magnetic target using scalar magnetometer array.

    PubMed

    Fan, Liming; Kang, Chong; Zhang, Xiaojun; Zheng, Quan; Wang, Ming

    2016-01-01

    The position of a magnetic target can be obtained through magnetic anomaly which is measured by a magnetic sensor. Comparing with vector magnetic sensor, the measurement value of the scalar magnetic sensor is almost not influenced by its orientation in measurement coordinate axes. Therefore, scalar magnetic sensors can be easily assembled into an array. Based on analysis of the total scalar magnetic anomaly measured by scalar magnetometer, we present an efficient method for tracking a magnetic target using scalar magnetometer array. In this method, we separate the position information and magnetic moment information of magnetic target by matrix transformation. Then, we can obtain the position of the magnetic target in real time by a scalar magnetometer array and a particle swarm optimization algorithm. In addition, the magnetic moment of the target can be estimated when the target's position had been calculated. The simulation shows that the position of the target can be calculated accurately and the relative error of the position is <5 %. The calculated magnetic moment of the target is close to the theoretical value. In addition, execution time of each calculation is <1 s. Thus, the position of the magnetic target can be obtained in real-time through this method.

  8. Geophysical Institute Magnetometer Array: Magnetic Field Data in Real-Time for Researchers

    NASA Astrophysics Data System (ADS)

    Wolf, V. G.; Hampton, D. L.

    2012-12-01

    Magnetometer data from eight remote stations across Alaska have been collected continuously since the early 1980's by the Geophysical Institute Magnetometer Array (GIMA). These three-axis, 1Hz data, with ~ 1 nT precision, are used to determine the currents associated with auroral activity in the Alaska polar regions. A primary function of the GIMA is to supply magnetic field deflection data in real time to researchers so they can determine when to launch a sub-orbital sounding rocket from the Poker Flat Research Range into the proper auroral conditions. The aurora is a key coupling mechanism between the Earth's magnetosphere and ionosphere, and the magnetometers are used to remotely sense the ionospheric currents associated with aurora. The real-time magnetometer data are displayed through a web-based interface that functions on desktop and mobile devices. The displays are highly configurable to allow researchers the flexibility to interpret the magnetic signature they need to make a successful launch decision. The data are also available for download within 24 hours of collection. The existence of real-time data has been and will continue to be critical for successful rocket launches, however the real-time system needs to improve to meet the ever growing needs of the user community. Planned upgrades will improve the reliability and resolution of the displays as well as the ease of data download, and integration into NASA virtual observatories.

  9. Comparing passive source localization and tracking approaches with a towed horizontal receiver array in an ocean waveguide.

    PubMed

    Gong, Zheng; Tran, Duong D; Ratilal, Purnima

    2013-11-01

    Approaches for instantaneous passive source localization using a towed horizontal receiver array in a random range-dependent ocean waveguide are examined. They include: (1) Moving array triangulation, (2) array invariant, (3) bearings-only target motion analysis in modified polar coordinates via the extended Kalman filter, and (4) bearings-migration minimum mean-square error. These methods are applied to localize and track a vertical source array deployed in the far-field of a towed horizontal receiver array during the Gulf of Maine 2006 Experiment. The source transmitted intermittent broadband pulses in the 300 to 1200 Hz frequency range. A nonlinear matched-filter kernel designed to replicate the acoustic signal measured by the receiver array is applied to enhance the signal-to-noise ratio. The source localization accuracy is found to be highly dependent on source-receiver geometry and the localization approach. For a relatively stationary source drifting at speeds much slower than the receiver array tow-speed, the mean source position can be estimated by moving array triangulation with less than 3% error near broadside direction. For a moving source, the Kalman filter method gives the best performance with 5.5% error. The array invariant is the best approach for localizing sources within the endfire beam of the receiver array with 7% error.

  10. Superconducting-quantum-interference-device array magnetometers with directly coupled pickup loop and serial flux dams

    NASA Astrophysics Data System (ADS)

    Wu, Chiu-Hsien; Yang, Hong-Chang; Chen, Ji-Cheng; Chen, Kuen-Lin; Chen, M. J.; Jeng, J. T.; Horng, Herng-Er

    2006-09-01

    In this work, we studied the engineering of high-transition-temperature superconductor Josephson junctions and superconducting quantum interference device (SQUID) by using step-edge or the bicrystal grain-boundary technologies. Serial Josephson junctions and bare SQUID array reveal high quality device characteristics. A high-Tc SQUID magnetometer exhibiting magnetic field sensitivity of 33fT/Hz1/2 in the white regime and 80fT/Hz1/2 at 1Hz was demonstrated by incorporating the flux dams and serial SQUID into the pickup loop of magnetometer. Furthermore, we demonstrate the opening of the flux dams by applying an external magnetic field to induce a current higher than the critical current of the serial flux dams. We show that the serial flux dams effectively suppress the low frequency 1/f-like noises.

  11. Enhanced Processing for a Towed Array Using an Optimal Noise Canceling Approach

    SciTech Connect

    Sullivan, E J; Candy, J V

    2005-07-21

    Noise self-generated by a surface ship towing an array in search of a weak target presents a major problem for the signal processing especially if broadband techniques are being employed. In this paper we discuss the development and application of an adaptive noise canceling processor capable of extracting the weak far-field acoustic target in a noisy ocean acoustic environment. The fundamental idea for this processor is to use a model-based approach incorporating both target and ship noise. Here we briefly describe the underlying theory and then demonstrate through simulation how effective the canceller and target enhancer perform. The adaptivity of the processor not only enables the ''tracking'' of the canceller coefficients, but also the estimation of target parameters for localization. This approach which is termed ''joint'' cancellation and enhancement produces the optimal estimate of both in a minimum (error) variance sense.

  12. Detection and Analysis of Low-Frequency Sperm Whale Vocalizations with a Towed Array

    NASA Astrophysics Data System (ADS)

    Bohn, Alexander

    Sperm whale vocalizations recorded during a sea test and calibration experiment in the Gulf of Maine on a single towed, horizontal, densely sampled, low-frequency (< 2500 Hz), coherent hydrophone array system are detected and analyzed for signal energy level and other characteristics. The vocalizing individuals are localized in bearing, range, and depth. An algorithm is developed to achieve automatic detection of vocalizations. This analysis is shown to have potential utility despite restriction to only the low-frequency component of the vocalizations by sampling theory. In addition, transmission loss in the New England continental shelf and slope environment is accounted for with an ocean waveguide-acoustic propagation model. Multiple averaged realizations of this model are used to estimate transmission loss as a function of range and depth for transects between the receiver array and vocalizing whales. Comparison of the vocalizations and background noise levels and the estimated transmission loss suggests the sperm whale detection range after coherent array processing exceeds 60 km in low-to-moderate sea states. Low-frequency source levels of vocalizations are estimated using the received levels and the estimated transmission loss, and applications of both this estimate and the receiver-side statistics are discussed.

  13. Fetal magnetocardiography measurements with an array of microfabricated optically pumped magnetometers

    NASA Astrophysics Data System (ADS)

    Alem, Orang; Sander, Tilmann H.; Mhaskar, Rahul; LeBlanc, John; Eswaran, Hari; Steinhoff, Uwe; Okada, Yoshio; Kitching, John; Trahms, Lutz; Knappe, Svenja

    2015-06-01

    Following the rapid progress in the development of optically pumped magnetometer (OPM) technology for the measurement of magnetic fields in the femtotesla range, a successful assembly of individual sensors into an array of nearly identical sensors is within reach. Here, 25 microfabricated OPMs with footprints of 1 cm3 were assembled into a conformal array. The individual sensors were inserted into three flexible belt-shaped holders and connected to their respective light sources and electronics, which reside outside a magnetically shielded room, through long optical and electrical cables. With this setup the fetal magnetocardiogram of a pregnant woman was measured by placing two sensor belts over her abdomen and one belt over her chest. The fetal magnetocardiogram recorded over the abdomen is usually dominated by contributions from the maternal magnetocardiogram, since the maternal heart generates a much stronger signal than the fetal heart. Therefore, signal processing methods have to be applied to obtain the pure fetal magnetocardiogram: orthogonal projection and independent component analysis. The resulting spatial distributions of fetal cardiac activity are in good agreement with each other. In a further exemplary step, the fetal heart rate was extracted from the fetal magnetocardiogram. Its variability suggests fetal activity. We conclude that microfabricated optically pumped magnetometers operating at room temperature are capable of complementing or in the future even replacing superconducting sensors for fetal magnetocardiography measurements.

  14. Operational field evaluation of the PAC-MAG man-portable magnetometer array

    NASA Astrophysics Data System (ADS)

    Keranen, Joe; Topolosky, Zeke; Schultz, Gregory; Miller, Jonathan

    2013-06-01

    Detection and discrimination of unexploded ordnance (UXO) in areas of prior conflict is of high importance to the international community and the United States government. For humanitarian applications, sensors and processing methods need to be robust, reliable, and easy to train and implement using indigenous UXO removal personnel. This paper describes system characterization, system testing, and a continental United States (CONUS) Operational Field Evaluations (OFE) of the PAC-MAG man-portable UXO detection system. System testing occurred at a government test facility in June, 2010 and December, 2011 and the OFE occurred at the same location in June, 2012. NVESD and White River Technologies personnel were present for all testing and evaluation. The PAC-MAG system is a manportable magnetometer array for the detection and characterization of ferrous UXO. System hardware includes four Cesium vapor magnetometers for detection, a Real-time Kinematic Global Position System (RTK-GPS) for sensor positioning, an electronics module for merging array data and WiFi communications and a tablet computer for transmitting and logging data. An odometer, or "hipchain" encoder, provides position information in GPS-denied areas. System software elements include data logging software and post-processing software for detection and characterization of ferrous anomalies. The output of the post-processing software is a dig list containing locations of potential UXO(s), formatted for import into the system GPS equipment for reacquisition of anomalies. Results from system characterization and the OFE will be described.

  15. Fetal magnetocardiography measurements with an array of microfabricated optically pumped magnetometers.

    PubMed

    Alem, Orang; Sander, Tilmann H; Mhaskar, Rahul; LeBlanc, John; Eswaran, Hari; Steinhoff, Uwe; Okada, Yoshio; Kitching, John; Trahms, Lutz; Knappe, Svenja

    2015-06-21

    Following the rapid progress in the development of optically pumped magnetometer (OPM) technology for the measurement of magnetic fields in the femtotesla range, a successful assembly of individual sensors into an array of nearly identical sensors is within reach. Here, 25 microfabricated OPMs with footprints of 1 cm(3) were assembled into a conformal array. The individual sensors were inserted into three flexible belt-shaped holders and connected to their respective light sources and electronics, which reside outside a magnetically shielded room, through long optical and electrical cables. With this setup the fetal magnetocardiogram of a pregnant woman was measured by placing two sensor belts over her abdomen and one belt over her chest. The fetal magnetocardiogram recorded over the abdomen is usually dominated by contributions from the maternal magnetocardiogram, since the maternal heart generates a much stronger signal than the fetal heart. Therefore, signal processing methods have to be applied to obtain the pure fetal magnetocardiogram: orthogonal projection and independent component analysis. The resulting spatial distributions of fetal cardiac activity are in good agreement with each other. In a further exemplary step, the fetal heart rate was extracted from the fetal magnetocardiogram. Its variability suggests fetal activity. We conclude that microfabricated optically pumped magnetometers operating at room temperature are capable of complementing or in the future even replacing superconducting sensors for fetal magnetocardiography measurements.

  16. Atomic Magnetometer Multisensor Array for rf Interference Mitigation and Unshielded Detection of Nuclear Quadrupole Resonance

    NASA Astrophysics Data System (ADS)

    Cooper, Robert J.; Prescott, David W.; Matz, Peter; Sauer, Karen L.; Dural, Nezih; Romalis, Michael V.; Foley, Elizabeth L.; Kornack, Thomas W.; Monti, Mark; Okamitsu, Jeffrey

    2016-12-01

    An array of four 87Rb vector magnetometers is used to detect nuclear quadrupole resonance signals in an unshielded environment at 1 MHz. With a baseline of 25 cm, the length of the array, radio-frequency interference mitigation is also demonstrated; a radio-station signal is suppressed by a factor of 20 without degradation to the signal of interest. With these compact sensors, in which the probe beam passes through twice, the fundamental limit to detection sensitivity is found to be photon-shot noise. More passes of the probe beam overcome this limitation. With a sensor of similar effective volume, 0.25 cm3 , but 25 × more passes, the sensitivity is improved by an order of magnitude to 1.7 ±0.2 fT /√{Hz } .

  17. Geospace Science from Ground-based Magnetometer Arrays: Advances in Sensors, Data Collection, and Data Integration

    NASA Astrophysics Data System (ADS)

    Mann, Ian; Chi, Peter

    2016-07-01

    , acceleration, and loss of electrons in the radiation belts promise high profile science returns. Integrated, global scale data products also have potential importance and application for real-time monitoring of the space weather threats to electrical power grids from geomagnetically induced currents. Such data exploitation increasingly relies on the collaborations between multiple national magnetometer arrays to generate single data products with common file format and data properties. We review advances in geospace science which can be delivered by networks of ground-based magnetometers - in terms of advances in sensors, data collection, and data integration - including through collaborations within the Ultra-Large Terrestrial International Magnetometer Array (ULTIMA) consortium.

  18. Multiplexed HTS rf SQUID magnetometer array for eddy current testing of aircraft rivet joints

    NASA Astrophysics Data System (ADS)

    Gärtner, S.; Krause, H.-J.; Wolters, N.; Lomparski, D.; Wolf, W.; Schubert, J.; Kreutzbruck, M. v.; Allweins, K.

    2002-05-01

    Using three rf SQUID magnetometers, a multiplexed SQUID array was implemented. The SQUIDs are positioned in line with 7 mm spacing and operated using one feedback electronics with sequential read out demodulation at different radio frequencies (rf). The cross-talk between SQUID channels was determined to be negligible. To show the performance of the SQUID array, eddy current (EC) measurements of aluminum aircraft samples in conjunction with a differential (double-D) EC excitation and lock-in readout were carried out. With computer-controlled continuous switching of the SQUIDs during the scan, three EC signal traces of the sample are obtained simultaneously. We performed measurements with an EC excitation frequency of 135 Hz to localize an artificial crack (sawcut flaw) of 20 mm length in an aluminum sheet with 0.6 mm thickness. The flaw was still detected when covered with aluminum of up to 10 mm thickness. In addition, measurements with varying angles between scanning direction and flaw orientation are presented.

  19. The 2011 Tohoku Tsunami observed by an array of ocean bottom electro-magnetometers

    NASA Astrophysics Data System (ADS)

    Utada, H.; Zhang, L.; Baba, K.; Liang, P.; Shimizu, H.

    2014-12-01

    Previous studies have claimed that EM sensors can be used as a type of tsunami sensor. In fact, recent studies have reported the observation of EM field variations possibly caused by devastating tsunamis including the 2011 Tohoku Tsunami. During the period from June 2010 to November 2011, we deployed a small array consisting of 4 ocean bottom electro-magnetometers (OBEMs) in the northwestern Pacific basin, about 1,000 km to the east from the epicenter, to explore the mantle structure. This array successfully recorded EM signals associated with the 2011 Tohoku Tsunami.We found that the observed EM signal propagated in the array as a wave with a phase velocity approximately equal to that of an oceanic long wave. Also, we estimated the motional impedance and tipper corresponding to the propagation direction at each site from the major components of observed EM signals and found that they were approximately equal to the phase velocities of the tsunami propagation as suggested by a simple theory. Besides, ocean bottom seismograms and tilt data show that observed EM variations were not produced by instrumental shaking. These results gave us a clear proof that observed EM signals were generated by the motional induction of the 2011 Tohoku Tsunami and therefore can be used to estimate tsunami parameters such as wave height, arrival time, and propagation direction.Then, we estimated the tsunami propagation direction from observed tsunami-induced EM fields at four seafloor sites through several methods (both single station and array analyses). Resulting frequency dependence of the propagation direction was found consistent with a source model of the 2011 Tohoku earthquake and tsunami. We also estimated the tsunami height from EM data recorded at each site, and obtained the tsunami amplitude in the array to be approximately 1 m. The same set of parameters (propagation direction and wave height) was calculated from EM signals simulated by using a tsunami flow model with a

  20. Synchronization sampling method based on delta-sigma analog-digital converter for underwater towed array system

    NASA Astrophysics Data System (ADS)

    Jiang, Jia-Jia; Duan, Fa-Jie; Li, Yan-Chao; Hua, Xiang-Ning

    2014-03-01

    Synchronization sampling is very important in underwater towed array system where every acquisition node (AN) samples analog signals by its own analog-digital converter (ADC). In this paper, a simple and effective synchronization sampling method is proposed to ensure synchronized operation among different ANs of the underwater towed array system. We first present a master-slave synchronization sampling model, and then design a high accuracy phase-locked loop to synchronize all delta-sigma ADCs to a reference clock. However, when the master-slave synchronization sampling model is used, both the time-delay (TD) of messages traveling along the wired transmission medium and the jitter of the clocks will bring out synchronization sampling error (SSE). Therefore, a simple method is proposed to estimate and compensate the TD of the messages transmission, and then another effective method is presented to overcome the SSE caused by the jitter of the clocks. An experimental system with three ANs is set up, and the related experimental results verify the validity of the synchronization sampling method proposed in this paper.

  1. Synchronization sampling method based on delta-sigma analog-digital converter for underwater towed array system.

    PubMed

    Jiang, Jia-Jia; Duan, Fa-Jie; Li, Yan-Chao; Hua, Xiang-Ning

    2014-03-01

    Synchronization sampling is very important in underwater towed array system where every acquisition node (AN) samples analog signals by its own analog-digital converter (ADC). In this paper, a simple and effective synchronization sampling method is proposed to ensure synchronized operation among different ANs of the underwater towed array system. We first present a master-slave synchronization sampling model, and then design a high accuracy phase-locked loop to synchronize all delta-sigma ADCs to a reference clock. However, when the master-slave synchronization sampling model is used, both the time-delay (TD) of messages traveling along the wired transmission medium and the jitter of the clocks will bring out synchronization sampling error (SSE). Therefore, a simple method is proposed to estimate and compensate the TD of the messages transmission, and then another effective method is presented to overcome the SSE caused by the jitter of the clocks. An experimental system with three ANs is set up, and the related experimental results verify the validity of the synchronization sampling method proposed in this paper.

  2. Investigating dynamical complexity in the time series of the upgraded ENIGMA magnetometer array using various entropy measures

    NASA Astrophysics Data System (ADS)

    Balasis, Georgios; Daglis, Ioannis A.; Papadimitriou, Constantinos; Melis, Nikolaos; Giannakis, Omiros; Kontoes, Charalampos

    2016-04-01

    The HellENIc GeoMagnetic Array (ENIGMA) is a network of 3 ground-based magnetometer stations in the areas of Trikala, Attiki and Lakonia in Greece that provides measurements for the study of geomagnetic pulsations, resulting from the solar wind - magnetosphere coupling. ENIGMA magnetometer array enables effective remote sensing of geospace dynamics and the study of space weather effects on the ground (i.e., Geomagnetically Induced Currents - GIC). ENIGMA contributes data to SuperMAG, a worldwide collaboration of organizations and national agencies that currently operate more than 300 ground-based magnetometers. ENIGMA is currently extended and upgraded receiving financial support through the national funding KRIPIS project and European Commission's BEYOND project. In particular, the REGPOT project BEYOND is an FP7 project that aims to maintain and expand the existing state-of-the-art interdisciplinary research potential, by Building a Centre of Excellence for Earth Observation based monitoring of Natural Disasters in south-eastern Europe, with a prospect to increase its access range to the wider Mediterranean region through the integrated cooperation with twining organizations. This study explores the applicability and effectiveness of a variety of computable entropy measures to the ENIGMA time series in order to investigate dynamical complexity between pre-storm activity and magnetic storms.

  3. A small towed beamforming array to identify vocalizing resident killer whales ( Orcinus orca) concurrent with focal behavioral observations

    NASA Astrophysics Data System (ADS)

    Miller, Patrick J.; Tyack, Peter L.

    Investigations of communication systems benefit from concurrent observation of vocal and visible behaviors of individual animals. A device has been developed to identify individual vocalizing resident killer whales ( Orcinus orca) during focal behavioral observations. The device consists of a 2-m, 15-element hydrophone array, which is easily towed behind a small vessel, on-board multi-channel recorders, and real-time signal processing equipment. Acoustic data from the hydrophones are digitized and processed using broadband frequency-domain beamforming to yield frequency-azimuth (FRAZ) and "directo-gram" displays of arriving sounds. Based upon statistical analysis of independent portions of typical killer whale calls, the precision of the angle-of-arrival estimate ranges from ±0° to ±2.5° with a mean precision of ±1.5°. Echolocation clicks also are resolved precisely with a typical -6 dB mainlobe width of ±2.0°. Careful positioning of the array relative to the animals minimizes the effects of depth ambiguities and allows identification of individual sources in many circumstances. Several strategies for identifying vocalizing individuals are discussed and an example of a successful identification is described. Use of the array with resident killer whales did not interfere with vessel maneuverability, animal tracking, or behavioral sampling of focal individuals. This localization technique has promise for advancing the abilities of researchers to conduct unbiased behavioral and acoustic sampling of individual free-ranging cetaceans.

  4. Effects of surveillance towed array sensor system (SURTASS) low frequency active sonar on fish

    NASA Astrophysics Data System (ADS)

    Popper, Arthur N.; Halvorsen, Michele B.; Miller, Diane; Smith, Michael E.; Song, Jiakun; Wysocki, Lidia E.; Hastings, Mardi C.; Kane, Andrew S.; Stein, Peter

    2005-04-01

    We investigated the effects of exposure to Low Frequency Active (LFA) sonar on rainbow trout (a hearing non-specialist related to several endangered salmonids) and channel catfish (a hearing specialist), using an element of the standard SURTASS LFA source array. We measured hearing sensitivity using auditory brainstem response, effects on inner ear structure using scanning electron microscopy, effects on non-auditory tissues using general pathology and histopathology, and behavioral effects with video monitoring. Exposure to 193 dB re 1 microPa (rms received level) in the LFA frequency band for 324 seconds resulted in a TTS of 20 dB at 400 Hz in rainbow trout, with less TTS at 100 and 200 Hz. TTS in catfish ranged from 6 to 12 dB at frequencies from 200 to 1000 Hz. Both species recovered from hearing loss in several days. Inner ears sensory tissues appeared unaffected by acoustic exposure. Gross pathology indicated no damage to non-auditory tissues, including the swim bladder. Both species showed consistent startle responses at sound onsets and changed their position relative to the sound source during exposures. There was no fish death attributable to sound exposure even up to four days post-exposure. [Work supported by Chief of Naval Operations.

  5. Demonstration of Helicopter Multi-Sensor Towed Array Detection System (MTADS) Magnetometry Technology at Victorville Precision Bombing Range, California

    DTIC Science & Technology

    2008-09-12

    Input Files Device Sample Rate (Hz) Data Type Filename extension Remarks Geometrics custom DAQ computer system trigger 100 TTL pulse...TriggerDevice.trig Generated and logged by the DAQ – initiates the magnetometer sampling Geometrics Model 822A Cs Magnetometers 100 RS232 - ASCII...data 20/10 RS232 - ASCII GPS.nmea Position data are in Trimble GGK message format, azimuth and roll are in Trimble AVR message format Trimble Model

  6. Demonstration of Helicopter Multi-Towed Array Detection System (MTADS) Magnetometry Technology at Pueblo Precision Bombing Range #2, Colorado

    DTIC Science & Technology

    2008-08-28

    Raw Data Input Files Device Sample Rate (Hz) Data Type Filename extension Remarks Geometrics custom DAQ computer system trigger 100 TTL pulse...TriggerDevice.trig Generated and logged by the DAQ – initiates the magnetometer sampling Geometrics Model 822A Cs Magnetometers 100 RS232 ...position/attitude data 20/10 RS232 - ASCII GPS.nmea Position data are in Trimble GGK message format, azimuth and roll are in Trimble AVR message

  7. MAVEN Magnetometer

    NASA Video Gallery

    MAVEN’s dual magnetometers will allow scientists to study the interactionbetween the solar wind and the Martian atmosphere, giving us a betterunderstanding of how Mars has evolved from a warm, ...

  8. Standardized UXO Technology Demonstration Site Blind Grid Scoring Record No. 806 (U.S. Geological Survey, TMGS Magnetometer/Towed Array)

    DTIC Science & Technology

    2007-05-01

    reference data are used primarily as a metric for overall accuracy. Abnormal drift, as would be caused by battery depletion or component degradation ...deemed degraded would be reacquired. Plans are to preprocess data overnight or concurrent with data acquisition to visually ensure that there are no...generally deeper than 1 meter. An X-ray diffraction analysis on four soil samples indicated a basic mineralogy of quartz, calcite , mica

  9. A Near-real-time Data Transport System for Selected Stations in the Magnetometer Array for Cusp and Cleft Studies (MACCS)

    NASA Astrophysics Data System (ADS)

    Engebretson, M. J.; Valentic, T. A.; Stehle, R. H.; Hughes, W. J.

    2004-05-01

    The Magnetometer Array for Cusp and Cleft Studies (MACCS) is a two-dimensional array of eight fluxgate magnetometers that was established in 1992-1993 in the Eastern Canadian Arctic from 75° to over 80° MLAT to study electrodynamic interactions between the solar wind and Earth's magnetosphere and high-latitude ionosphere. A ninth site in Nain, Labrador, extends coverage down to 66° between existing Canadian and Greenland stations. Originally designed as part of NSF's GEM (Geospace Environment Modeling) Program, MACCS has contributed to the study of transients and waves at the magnetospheric boundary and in the near-cusp region as well as to large, cooperative, studies of ionospheric convection and substorm processes. Because of the limitations of existing telephone lines to each site, it has not been possible to economically access MACCS data promptly; instead, each month's collected data is recorded and mailed to the U.S. for processing and eventual posting on a publicly-accessible web site, http://space.augsburg.edu/space. As part of its recently renewed funding, NSF has supported the development of a near-real-time data transport system using the Iridium satellite network, which will be implemented at two MACCS sites in summer 2004. At the core of the new MACCS communications system is the Data Transport Network, software developed with NSF-ITR funding to automate the transfer of scientific data from remote field stations over unreliable, bandwidth-constrained network connections. The system utilizes a store-and-forward architecture based on sending data files as attachments to Usenet messages. This scheme not only isolates the instruments from network outages, but also provides a consistent framework for organizing and accessing multiple data feeds. Client programs are able to subscribe to data feeds to perform tasks such as system health monitoring, data processing, web page updates and e-mail alerts. The MACCS sites will employ the Data Transport Network

  10. Atomic magnetometer

    DOEpatents

    Schwindt, Peter [Albuquerque, NM; Johnson, Cort N [Albuquerque, NM

    2012-07-03

    An atomic magnetometer is disclosed which uses a pump light beam at a D1 or D2 transition of an alkali metal vapor to magnetically polarize the vapor in a heated cell, and a probe light beam at a different D2 or D1 transition to sense the magnetic field via a polarization rotation of the probe light beam. The pump and probe light beams are both directed along substantially the same optical path through an optical waveplate and through the heated cell to an optical filter which blocks the pump light beam while transmitting the probe light beam to one or more photodetectors which generate electrical signals to sense the magnetic field. The optical waveplate functions as a quarter waveplate to circularly polarize the pump light beam, and as a half waveplate to maintain the probe light beam linearly polarized.

  11. Development of Autonomous Magnetometer Rotorcraft For Wide Area Assessment

    SciTech Connect

    Mark D. McKay; Matthew O. Anderson

    2011-08-01

    Large areas across the United States and internationally are potentially contaminated with unexploded ordinance (UXO), with some ranges encompassing tens to hundreds of thousands of acres. Technologies are needed which will allow for cost effective wide area scanning with (1) near 100% coverage and (2) near 100% detection of subsurface ordnance or features indicative of subsurface ordnance. The current approach to wide area assessment is a multi-level one, in which medium - altitude fixed wing optical imaging is used for an initial site assessment. This assessment is followed with low altitude manned helicopter based magnetometry. Subsequent to this wide area assessment targeted surface investigations are performed using either towed geophysical sensor arrays or man portable sensors. In order to be an effective tool for small UXO detection, the sensing altitude for magnetic site investigations needs to be on the order of 1 to 3 meters. These altitude requirements mean that manned helicopter surveys will generally only be feasible in large, open and relatively flat terrains. While such surveys are effective in mapping large areas relatively fast there are substantial mobilization/demobilization, staffing and equipment costs associated with these surveys, resulting in costs of approximately $100-$150/acre. In addition, due to the low altitude there are substantial risks to pilots and equipment. Surface towed arrays provide highresolution maps but have other limitations, e.g. in their ability to navigate rough terrain effectively. Thus there is a need for other systems, which can be used for effective data collection. An Unmanned Aerial Vehicle (UAV) magnetometer platform is an obvious alternative. The motivation behind such a system is that it reduces risk to operators, is lower in initial and Operational and Maintenance (O&M) costs (and can thus potentially be applied to smaller sites) and has the potential of being more effective in terms of detection and possibly

  12. Development of autonomous magnetometer rotorcraft for wide area assessment

    SciTech Connect

    Roelof Versteeg; Matt Anderson; Les Beard; Eric Corban; Darryl Curley; Jeff Gamey; Ross Johnson; Dwight Junkin; Mark McKay; Jared Salzmann; Mikhail Tchernychev; Suraj Unnikrishnan; Scott Vinson

    2010-04-01

    Large areas across the United States are potentially contaminated with UXO, with some ranges encompassing tens to hundreds of thousands of acres. Technologies are needed which will allow for cost effective wide area scanning with 1) near 100 % coverage and 2) near 100 % detection of subsurface ordnance or features indicative of subsurface ordnance. The current approach to wide area assessment is a multi-level one, in which medium - altitude fixed wing optical imaging is used for an initial site assessment. This assessment is followed with low altitude manned helicopter based magnetometry. Subsequent to this wide area assessment targeted surface investigations are performed using either towed geophysical sensor arrays or man portable sensors. In order to be an effective tool for small UXO detection, the sensing altitude for magnetic site investigations needs to be on the order of 1 – 3 meters. These altitude requirements mean that manned helicopter surveys will generally only be feasible in large, open and relatively flat terrains. While such surveys are effective in mapping large areas relatively fast there are substantial mobilization/demobilization, staffing and equipment costs associated with these surveys (resulting in costs of approximately $100-$150/acre). In addition, due to the low altitude there are substantial risks to pilots and equipment. Surface towed arrays provide high resolution maps but have other limitations, e.g. in their ability to navigate rough terrain effectively. There is thus a need for other systems which can be used for effective data collection. An UAV (Unmanned Aerial Vehicle) magnetometer platform is an obvious alternative. The motivation behind such a system is that it reduces risk to operators, is lower in initial and Operational and Maintenance (O&M) costs (and can thus potentially be applied to smaller sites) and has the potential of being more effective in terms of detection and possibly characterization (through the use of

  13. STAR Towed Array Display Upgrade

    DTIC Science & Technology

    2005-12-01

    Processing Packages ou logiciels de traitement du signal). La suite STAR est mise en œuvre au moyen du langage IDL (Interactive Data Language), bien...que sa conception ne soit pas restreinte à ce langage , et elle a été élaborée en premier lieu pour l’analyse des données des bouées acoustiques

  14. 2011 ESTCP Live Site Demonstrations, Vallejo CA, ESTCP MR-1165, Demonstration Data Report, Former Mare Island Naval Shipyard, MTADS Discrimination Array, (TEMTADS) Survey

    DTIC Science & Technology

    2012-04-05

    RTK GPS System ..................................................................................................... 16  5.3.3  Time-Domain...over large areas (10 - 25 acres / day) to detect buried UXO. The MTADS tow vehicle and magnetometer array are shown in Figure 5-2. 5.3.2 RTK GPS ...System Positioning is provided using cm-level Real Time Kinematic ( RTK ) Global Positioning System ( GPS ) receivers. To achieve cm-level precision, a

  15. Kinetic inductance magnetometer.

    PubMed

    Luomahaara, Juho; Vesterinen, Visa; Grönberg, Leif; Hassel, Juha

    2014-09-10

    Sensing ultra-low magnetic fields has various applications in the fields of science, medicine and industry. There is a growing need for a sensor that can be operated in ambient environments where magnetic shielding is limited or magnetic field manipulation is involved. To this end, here we demonstrate a new magnetometer with high sensitivity and wide dynamic range. The device is based on the current nonlinearity of superconducting material stemming from kinetic inductance. A further benefit of our approach is of extreme simplicity: the device is fabricated from a single layer of niobium nitride. Moreover, radio frequency multiplexing techniques can be applied, enabling the simultaneous readout of multiple sensors, for example, in biomagnetic measurements requiring data from large sensor arrays.

  16. Multi-sensor magnetoencephalography with atomic magnetometers

    PubMed Central

    Johnson, Cort N; Schwindt, P D D; Weisend, M

    2014-01-01

    The authors have detected magnetic fields from the human brain with two independent, simultaneously operating rubidium spin-exchange-relaxation-free magnetometers. Evoked responses from auditory stimulation were recorded from multiple subjects with two multi-channel magnetometers located on opposite sides of the head. Signal processing techniques enabled by multi-channel measurements were used to improve signal quality. This is the first demonstration of multi-sensor atomic magnetometer magnetoencephalography and provides a framework for developing a non-cryogenic, whole-head magnetoencephalography array for source localization. PMID:23939051

  17. Feasibility Study for an Autonomous UAV -Magnetometer System -- Final Report on SERDP SEED 1509:2206

    SciTech Connect

    Roelof Versteeg; Mark McKay; Matt Anderson; Ross Johnson; Bob Selfridge; Jay Bennett

    2007-09-01

    Large areas across the United States are potentially contaminated with UXO, with some ranges encompassing tens to hundreds of thousands of acres. Technologies are needed which will allow for cost effective wide area scanning with 1) near 100 % coverage and 2) near 100 % detection of subsurface ordnance or features indicative of subsurface ordnance. The current approach to wide area scanning is a multi-level one, in which medium altitude fixed wing optical imaging is used for an initial site assessment. This assessment is followed with low altitude manned helicopter based magnetometry followed by surface investigations using either towed geophysical sensor arrays or man portable sensors. In order to be effective for small UXO detection, the sensing altitude for magnetic site investigations needs to be on the order of 1 – 3 meters. These altitude requirements means that manned helicopter surveys will generally only be feasible in large, open and relatively flat terrains. While such surveys are effective in mapping large areas relatively fast there are substantial mobilization/demobilization, staffing and equipment costs associated with these surveys (resulting in costs of approximately $100-$150/acre). Surface towed arrays provide high resolution maps but have other limitations, e.g. in their ability to navigate rough terrain effectively. Thus, other systems are needed allowing for effective data collection. An UAV (Unmanned Aerial Vehicle) magnetometer platform is an obvious alternative. The motivation behind such a system is that it would be safer for the operators, cheaper in initial and O&M costs, and more effective in terms of site characterization. However, while UAV data acquisition from fixed wing platforms for large (> 200 feet) stand off distances is relatively straight forward, a host of challenges exist for low stand-off distance (~ 6 feet) UAV geophysical data acquisition. The objective of SERDP SEED 1509:2006 was to identify the primary challenges

  18. Automated real-time monitoring of the plasmasphere by means of ground-based magnetometer arrays in Europe and South Africa

    NASA Astrophysics Data System (ADS)

    Neska, M.; Collier, A.; Heilig, B.; Jozwiak, W.; Raita, T.; Vellante, M.

    2013-12-01

    The EMMA (Europe) / SANSA (South Africa) magnetometer network created in the frame of the PLASMON project serves for determining the plasmasphere's mass distribution basing on the FLR (field line resonance) technique. This determination shall be done in a fully automated way and in real time. Current data from all stations are delivered to the PLASMON center within ca. 10 minutes. The central server performs a detection of FLR frequencies for appropriate magnetometer pairs according to the FLRID algorithm. Subsequently, the plasmasphere's mass is determined by the FLRINV algorithm. First results of the whole system's working are presented.

  19. Magnetic Gradiometer and Vector Magnetometer Survey of the Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Granot, R.

    2014-12-01

    Some of the fundamental tectonic problems of the Eastern Mediterranean remain unresolved due to the extremely thick sedimentary cover (~15 km) and the lack of accurate magnetic anomaly data. We conducted a magnetic survey of the Herodotus and Levant Basins (Eastern Mediterranean) to study the nature and age of the underlying igneous crust. The towed magnetometer array consisted of two Overhauser sensors recording the total magnetic field in a longitudinal gradiometer mode, and a marine vector magnetometer. Accurate navigation together with the gradiometer data allows the separation of the magnetic signature of the lithosphere from the contributions of the external magnetic field and the geomagnetic field. Total field data in the Herodotus Basin reveal a sequence of long-wavelength NE-SW lineated anomalies (~80 nT) suggesting a deep (~20 km) 2D magnetic source layer. Analysis of the vector data shows a steady azimuth of lineations that is generally consistent with the total field anomalies. The sequence of anomalies is rather short and does not allow a unique identification. However, the continuous northward motion of the African Plate during the Paleozoic and Mesozoic result in predictable anomaly skewness patterns for the different time periods. Forward magnetic modeling best fit the observed anomalies when using Early Permian remanence directions. Altogether, these observations and analysis suggest that a Neo-Tethyan Permian oceanic crust underlies the Herodotus Basin. Two short-wavelengths and strong (~400 nT) anomalies are found in the Levant Basin, proposing rather shallow (~7 km) magnetic sources there. These anomalies spatially coincide with Mesozoic uplifted continental structures (Eratosthenes and Jonah Highs).

  20. Light-shift suppression in a miniaturized Mx optically pumped Cs magnetometer array with enhanced resonance signal using off-resonant laser pumping.

    PubMed

    Scholtes, Theo; Schultze, Volkmar; IJsselsteijn, Rob; Woetzel, Stefan; Meyer, Hans-Georg

    2012-12-31

    The performance of an optically pumped Mx magnetometer with miniaturized Cs cell at earth's magnetic field strength (50 μT) is investigated. Operation using detuned high intensity laser light is shown to be superior to the conventional resonant operation in terms of the projected shot-noise-limited ( 50 fT/√Hz) and the actual noise-limited sensitivity using a noise compensation method. The Zeeman light shift effect, emerging due to the off-resonant circularly polarized laser radiation and leading to a strong orientational dependence of the measurement, is suppressed by averaging two identical magnetometer configurations pumped with oppositely circularly polarized light. A residual heading error within the range of 14 nT, limited by the present experimental characterization setup, was achieved.

  1. Aristoteles magnetometer system

    NASA Astrophysics Data System (ADS)

    Smith, Edward J.; Marquedant, Roy J.; Langel, Robert; Acuna, Mario

    1991-12-01

    A magnetometer system capable of meeting the stringent requirements of the Aristoteles mission is described. The system will comprise a three axis or Vector Flux gas Magnetometer (VFM) and a highly accurate resonance magnetometer, the Scalar Helium Magnetometer (SHM). Basic operational features of these instruments are described and their performance is related to the scientific objectives of the mission appropriate to the geomagnetic field measurements. The major requirements imposed on the spacecraft are summarized. Photographs and diagrams of both instruments are presented along with graphs of the sensitivity of the SHM to magnetic field orientation.

  2. Atomic magnetometer for human magnetoencephalograpy.

    SciTech Connect

    Schwindt, Peter; Johnson, Cort N.

    2010-12-01

    We have developed a high sensitivity (<5 fTesla/{radical}Hz), fiber-optically coupled magnetometer to detect magnetic fields produced by the human brain. This is the first demonstration of a noncryogenic sensor that could replace cryogenic superconducting quantum interference device (SQUID) magnetometers in magnetoencephalography (MEG) and is an important advance in realizing cost-effective MEG. Within the sensor, a rubidium vapor is optically pumped with 795 laser light while field-induced optical rotations are measured with 780 nm laser light. Both beams share a single optical axis to maximize simplicity and compactness. In collaboration with neuroscientists at The Mind Research Network in Albuquerque, NM, the evoked responses resulting from median nerve and auditory stimulation were recorded with the atomic magnetometer and a commercial SQUID-based MEG system with signals comparing favorably. Multi-sensor operation has been demonstrated with two AMs placed on opposite sides of the head. Straightforward miniaturization would enable high-density sensor arrays for whole-head magnetoencephalography.

  3. Tuned cavity magnetometer sensitivity.

    SciTech Connect

    Okandan, Murat; Schwindt, Peter

    2009-09-01

    We have developed a high sensitivity (magnetometer that utilizes a novel optical (interferometric) detection technique. Further miniaturization and low-power operation are key advantages of this magnetometer, when compared to systems using SQUIDs which require liquid Helium temperatures and associated overhead to achieve similar sensitivity levels.

  4. Wireless, Acoustically Linked, Undersea, Magnetometer Sensor Network

    DTIC Science & Technology

    2010-06-01

    85 dB greater than the noise floor of the He3 magnetometer in the mHz band. The gradiometer data shown in Figure 1 is generated by a time series...Comparison of ground coupled and uncoupled gradiometer power spectral density for a wired array system. TABLE I MODEM INTERFERENCE DURATION (SECS) 28 Byte

  5. Acoustic-Sensing Underwater Tow Cable

    DTIC Science & Technology

    2013-09-30

    cable. The towed sensor system includes an array of hydrophones designed to sense a variety of underwater acoustic signals based on a particular...made from a flexible waterproof material such as polyurethane, nylon, or high-density polyethylene. The jacket 16 serves as the substrate for a...Encasing the regions 18, the conductors 20, as well as exposed portions of the jacket 16, is another waterproof jacket 22. The jacket 22 can be

  6. Microfabricated Optically-Pumped Magnetometers for Biomagnetic Applications

    NASA Astrophysics Data System (ADS)

    Knappe, Svenja; Alem, Orang; Sheng, Dong; Kitching, John

    2016-06-01

    We report on the progress in developing microfabricated optically-pumped magnetometer arrays for imaging applications. We have improved our sensitivities by several orders of magnitude in the last ten years. Now, our zero-field magnetometers reach noise values below 15 fT/Hz1/2. Recently, we have also developed gradiometers to reject ambient magnetic field noise. We have built several imaging arrays and validated them for biomedical measurements of brain and heart activity.

  7. Magnetometer uses bismuth-selenide

    NASA Technical Reports Server (NTRS)

    Woollman, J. A.; Spain, I. L.; Beale, H.

    1972-01-01

    Characteristics of bismuth-selenide magnetometer are described. Advantages of bismuth-selenide magnetometer over standard magnetometers are stressed. Thermal stability of bismuth-selenide magnetometer is analyzed. Linearity of output versus magnetic field over wide range of temperatures is reported.

  8. Hall effect magnetometer

    NASA Technical Reports Server (NTRS)

    Woollam, J. A.; Beale, H. A.; Spain, I. L. (Inventor)

    1974-01-01

    A magnetometer which uses a single crystal of bismuth selenide is described. The rhombohedral crystal structure of the sensing element is analyzed. The method of construction of the magnetometer is discussed. It is stated that the sensing crystal has a positive or negative Hall coefficient and a carrier concentration of about 10 to the 18th power to 10 to the 20th power per cubic centimeter.

  9. Flux-coherent series SQUID array magnetometers operating above 77 K with superior white flux noise than single-SQUIDs at 4.2 K

    SciTech Connect

    Chesca, Boris John, Daniel; Mellor, Christopher J.

    2015-10-19

    A very promising direction to improve the sensitivity of magnetometers based on superconducting quantum interference devices (SQUIDs) is to build a series-array of N non-interacting SQUIDs operating flux-coherently, because in this case their voltage modulation depth, ΔV, linearly scales with N whereas the white flux noise S{sub Φ}{sup 1/2} decreases as 1/N{sup 1/2}. Here, we report the realization of both these improvements in an advanced layout of very large SQUID arrays made of YBa{sub 2}Cu{sub 3}O{sub 7}. Specially designed with large area narrow flux focusers for increased field sensitivity and improved flux-coherency, our arrays have extremely low values for S{sub Φ}{sup 1/2} between (0.25 and 0.44) μΦ{sub 0}/Hz{sup 1/2} for temperatures in the range (77–83) K. In this respect, they outperform niobium/aluminium trilayer technology-based single-SQUIDs operating at 4.2 K. Moreover, with values for ΔV and transimpedance in the range of (10–17) mV and (0.3–2.5) kΩ, respectively, a direct connection to a low-noise room temperature amplifier is allowed, while matching for such readout is simplified and the available bandwidth is greatly increased. These landmark performances suggest such series SQUID arrays are ideal candidates to replace single-SQUIDs operating at 4.2 K in many applications.

  10. Cavity optomechanical magnetometer.

    PubMed

    Forstner, S; Prams, S; Knittel, J; van Ooijen, E D; Swaim, J D; Harris, G I; Szorkovszky, A; Bowen, W P; Rubinsztein-Dunlop, H

    2012-03-23

    A cavity optomechanical magnetometer is demonstrated. The magnetic-field-induced expansion of a magnetostrictive material is resonantly transduced onto the physical structure of a highly compliant optical microresonator and read out optically with ultrahigh sensitivity. A peak magnetic field sensitivity of 400  nT  Hz(-1/2) is achieved, with theoretical modeling predicting the possibility of sensitivities below 1  pT  Hz(-1/2). This chip-based magnetometer combines high sensitivity and large dynamic range with small size and room temperature operation.

  11. Tuned optical cavity magnetometer

    DOEpatents

    Okandan, Murat; Schwindt, Peter

    2010-11-02

    An atomic magnetometer is disclosed which utilizes an optical cavity formed from a grating and a mirror, with a vapor cell containing an alkali metal vapor located inside the optical cavity. Lasers are used to magnetically polarize the alkali metal vapor and to probe the vapor and generate a diffracted laser beam which can be used to sense a magnetic field. Electrostatic actuators can be used in the magnetometer for positioning of the mirror, or for modulation thereof. Another optical cavity can also be formed from the mirror and a second grating for sensing, adjusting, or stabilizing the position of the mirror.

  12. A Web Server for MACCS Magnetometer Data

    NASA Technical Reports Server (NTRS)

    Engebretson, Mark J.

    1998-01-01

    NASA Grant NAG5-3719 was provided to Augsburg College to support the development of a web server for the Magnetometer Array for Cusp and Cleft Studies (MACCS), a two-dimensional array of fluxgate magnetometers located at cusp latitudes in Arctic Canada. MACCS was developed as part of the National Science Foundation's GEM (Geospace Environment Modeling) Program, which was designed in part to complement NASA's Global Geospace Science programs during the decade of the 1990s. This report describes the successful use of these grant funds to support a working web page that provides both daily plots and file access to any user accessing the worldwide web. The MACCS home page can be accessed at http://space.augsburg.edu/space/MaccsHome.html.

  13. THOR Fluxgate Magnetometer (MAG)

    NASA Astrophysics Data System (ADS)

    Nakamura, Rumi; Eastwood, Jonathan; Magnes, Werner; Valavanoglou, Aris; Carr, Christopher M.; O'Brien, Helen L.; Narita, Yasuhito; Delva, Magda; Chen, Christopher H. K.; Plaschke, Ferdinand; Soucek, Jan

    2016-04-01

    Turbulence Heating ObserveR (THOR) is the first mission ever flown in space dedicated to plasma turbulence. The goal of the Fluxgate Magnetometer (MAG) is to measure the DC to low frequency ambient magnetic field. The design of the magnetometer consists of two tri-axial sensors and the related magnetometer electronics; the electronics are hosted on printed circuit boards in the common electronics box of the fields and wave processor (FWP). A fully redundant two sensor system mounted on a common boom and the new miniaturized low noise design based on MMS and Solar Orbiter instruments enable accurate measurement throughout the region of interest for THOR science. The usage of the common electronics hosted by FWP guarantees to fulfill the required timing accuracy with other fields measurements. These improvements are important to obtain precise measurements of magnetic field, which is essential to estimate basic plasma parameters and correctly identify the spatial and temporal scales of the turbulence. Furthermore, THOR MAG provides high quality data with sufficient overlap with the Search Coil Magnetometer (SCM) in frequency space to obtain full coverage of the wave forms over all the frequencies necessary to obtain the full solar wind turbulence spectrum from MHD to kinetic range with sufficient accuracy.

  14. Simple Magnetometer for Autopilots

    NASA Technical Reports Server (NTRS)

    Garner, H. D.

    1982-01-01

    Simple, low-cost magnetometer is suitable for heading-reference applications in autopilots and other directional control systems. Sensing element utilizes commercially available transformer core; and supporting electronics consist of one transistor, two readily-available integrated-circuit chips, and associated resistors and capacitors.

  15. The Magnetospheric Multiscale Magnetometers

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Anderson, B. J.; Baumjohann, W.; Bromund, K. R.; Dearborn, D.; Fischer, D.; Le, G.; Leinweber, H. K.; Leneman, D.; Magnes, W.; Means, J. D.; Moldwin, M. B.; Nakamura, R.; Pierce, D.; Plaschke, F.; Rowe, K. M.; Slavin, J. A.; Strangeway, R. J.; Torbert, R.; Hagen, C.; Jernej, I.; Valavanoglou, A.; Richter, I.

    2016-03-01

    The success of the Magnetospheric Multiscale mission depends on the accurate measurement of the magnetic field on all four spacecraft. To ensure this success, two independently designed and built fluxgate magnetometers were developed, avoiding single-point failures. The magnetometers were dubbed the digital fluxgate (DFG), which uses an ASIC implementation and was supplied by the Space Research Institute of the Austrian Academy of Sciences and the analogue magnetometer (AFG) with a more traditional circuit board design supplied by the University of California, Los Angeles. A stringent magnetic cleanliness program was executed under the supervision of the Johns Hopkins University's Applied Physics Laboratory. To achieve mission objectives, the calibration determined on the ground will be refined in space to ensure all eight magnetometers are precisely inter-calibrated. Near real-time data plays a key role in the transmission of high-resolution observations stored on board so rapid processing of the low-resolution data is required. This article describes these instruments, the magnetic cleanliness program, and the instrument pre-launch calibrations, the planned in-flight calibration program, and the information flow that provides the data on the rapid time scale needed for mission success.

  16. Gradient magnetometer system balloons

    NASA Astrophysics Data System (ADS)

    Korepanov, Valery; Tsvetkov, Yury

    2005-08-01

    Earth's magnetic field study still remains one of the leading edges of experimental geophysics. Thus study is executed on the Earth surface, including ocean bottom, and on satellite heights using component, mostly flux-gate magnetometers. But balloon experiments with component magnetometers are very seldom, first of all because of great complexity of data interpretation. This niche still waits for new experimental ideology, which will allow to get the measurements results with high accuracy, especially in gradient mode. The great importance of precise balloon-borne component magnetic field gradient study is obvious. Its technical realization is based both on the available at the marked high-precision non-magnetic tiltmeters and on recent achievements of flux-gate magnetometry. The scientific goals of balloon-borne magnetic gradiometric experiment are discussed and its practical realization is proposed.

  17. Dynamic Tow Maneuver Orbital Launch Technique

    NASA Technical Reports Server (NTRS)

    Rutan, Elbert L. (Inventor)

    2014-01-01

    An orbital launch system and its method of operation use a maneuver to improve the launch condition of a booster rocket and payload. A towed launch aircraft, to which the booster rocket is mounted, is towed to a predetermined elevation and airspeed. The towed launch aircraft begins the maneuver by increasing its lift, thereby increasing the flight path angle, which increases the tension on the towline connecting the towed launch aircraft to a towing aircraft. The increased tension accelerates the towed launch aircraft and booster rocket, while decreasing the speed (and thus the kinetic energy) of the towing aircraft, while increasing kinetic energy of the towed launch aircraft and booster rocket by transferring energy from the towing aircraft. The potential energy of the towed launch aircraft and booster rocket is also increased, due to the increased lift. The booster rocket is released and ignited, completing the launch.

  18. The IRM fluxgate magnetometer

    NASA Technical Reports Server (NTRS)

    Luehr, H.; Kloecker, N.; Oelschlaegel, W.; Haeusler, B.; Acuna, M.

    1985-01-01

    This report describes the three-axis fluxgate magnetometer instrument on board the AMPTE IRM spacecraft. Important features of the instrument are its wide dynamic range (0.1-60,000 nT), a high resolution (16-bit analog to digital conversion) and the capability to operate automatically or via telecommand in two gain states. In addition, the wave activity is monitored in all three components up to 50 Hz. Inflight checkout proved the nominal functioning of the instrument in all modes.

  19. Optical atomic magnetometer

    DOEpatents

    Budker, Dmitry; Higbie, James; Corsini, Eric P

    2013-11-19

    An optical atomic magnetometers is provided operating on the principles of nonlinear magneto-optical rotation. An atomic vapor is optically pumped using linearly polarized modulated light. The vapor is then probed using a non-modulated linearly polarized light beam. The resulting modulation in polarization angle of the probe light is detected and used in a feedback loop to induce self-oscillation at the resonant frequency.

  20. A multichannel portable SERF atomic magnetometer for biomagnetic measurement

    NASA Astrophysics Data System (ADS)

    Wyllie, Robert; Kauer, Matthew; Smetana, Gregory; Wakai, Ronald; Walker, Thad

    2011-05-01

    We present a portable four-channel atomic magnetometer array operating in the spin exchange relaxation-free regime. Each channel was operated with a baseline sensitivity of 5-10 fT /√{ Hz } , at or near the expected Johnson noise limit of the mu-metal shielding. The magnetometer array has several design features intended to maximize its suitability for fetal magnetocardiography, such as a compact modular design, fiber coupled lasers, and magnetometer channel spacing adjustable from 5-10 cm. We present adult magnetocardiogram using this array in a magnetically shielded room. We also show the acquisition and analysis of phantom fetal signals with a peak QRS amplitude of ~1pt, using an advanced nonlinear denoising algorithm. Funding from the NIH.

  1. Towed and AUV Technologies for Arctic Operations

    NASA Astrophysics Data System (ADS)

    Singh, H.; Eustice, R.; Humphris, S.; Jakuba, M.; Kunz, C.; Murphy, C.; Nakamura, K.; Reves-Sohn, R.; Roman, C.; Sato, T.; Shank, T.; Willis, C.

    2007-12-01

    equipped with a 230 kHz multibeam, a digital still camera and strobe, a magnetometer and an Eh sensor. Several drift dives were carried out with the CAMPER towed vehicle at two different sites on the Gakkel Ridge this summer and yielded considerable high definition and video imagery as well as geological and biological samples. Several dives were also carried for mapping the mid-water column and the seafloor with the two AUVs and these successfully returned water column CTD, Eh, optical backscatter, magnetic and multibeam data.

  2. Correcting GOES-R Magnetometer Data for Stray Fields

    NASA Technical Reports Server (NTRS)

    Carter, Delano R.; Freesland, Douglas C.; Tadikonda, Sivakumara K.; Kronenwetter, Jeffrey; Todirita, Monica; Dahya, Melissa; Chu, Donald

    2016-01-01

    Time-varying spacecraft magnetic fields or stray fields are a problem for magnetometer systems. While constant fields can be removed with zero offset calibration, stray fields are difficult to distinguish from ambient field variations. Putting two magnetometers on a long boom and solving for both the ambient and stray fields can be a good idea, but this gradiometer solution is even more susceptible to noise than a single magnetometer. Unless the stray fields are larger than the magnetometer noise, simply averaging the two measurements is a more accurate approach. If averaging is used, it may be worthwhile to explicitly estimate and remove stray fields. Models and estimation algorithms are provided for solar array, arcjet and reaction wheel fields.

  3. Correcting GOES-R Magnetometer Data for Stray Fields

    NASA Technical Reports Server (NTRS)

    Carter, Delano; Freesland, Douglas; Tadikonda, Sivakumar; Kronenwetter, Jeffrey; Todirita, Monica; Dahya, Melissa; Chu, Donald

    2016-01-01

    Time-varying spacecraft magnetic fields, i.e. stray fields, are a problem for magnetometer systems. While constant fields can be removed by calibration, stray fields are difficult to distinguish from ambient field variations. Putting two magnetometers on a long boom and solving for both the ambient and stray fields can help, but this gradiometer solution is more sensitive to noise than a single magnetometer. As shown here for the R-series Geostationary Operational Environmental Satellites (GOES-R), unless the stray fields are larger than the noise, simply averaging the two magnetometer readings gives a more accurate solution. If averaging is used, it may be worthwhile to estimate and remove stray fields explicitly. Models and estimation algorithms to do so are provided for solar array, arcjet and reaction wheel fields.

  4. Correcting GOES-R Magnetometer Data for Stray Fields

    NASA Astrophysics Data System (ADS)

    Carter, Delano; Freesland, Douglas; Tadikonda, Sivakumara K.; Kronenwetter, Jeffrey; Todirita, Monica; Dahya, Melissa; Chu, Donald

    2016-05-01

    Time-varying spacecraft magnetic fields, i.e. stray fields, are a problem for magnetometer systems. While constant fields can be removed by calibration, stray fields are difficult to distinguish from ambient field variations. Putting two magnetometers on a long boom and solving for both the ambient and stray fields can help, but this gradiometer solution is more sensitive to noise than a single magnetometer. As shown here for the R-series Geostationary Operational Environmental Satellites (GOES-R), unless the stray fields are larger than the noise, simply averaging the two magnetometer readings gives a more accurate solution. If averaging is used, it may be worthwhile to estimate and remove stray fields explicitly. Models and estimation algorithms to do so are provided for solar array, arcjet and reaction wheel fields.

  5. Towed Array Flow Noise Test Apparatus

    DTIC Science & Technology

    2010-09-30

    on tape or wire, optical or magnetic 17 reading of printed characters (e.g., OCR and magnetically encoded symbols) and machine-readable symbols...analog to digital converter ("ADC") or one or more ADCs or multiplexed ADC channels can reside within a microcomputer package. It is also understood

  6. Superconductive imaging surface magnetometer

    DOEpatents

    Overton, Jr., William C.; van Hulsteyn, David B.; Flynn, Edward R.

    1991-01-01

    An improved pick-up coil system for use with Superconducting Quantum Interference Device gradiometers and magnetometers involving the use of superconducting plates near conventional pick-up coil arrangements to provide imaging of nearby dipole sources and to deflect environmental magnetic noise away from the pick-up coils. This allows the practice of gradiometry and magnetometry in magnetically unshielded environments. One embodiment uses a hemispherically shaped superconducting plate with interior pick-up coils, allowing brain wave measurements to be made on human patients. another embodiment using flat superconducting plates could be used in non-destructive evaluation of materials.

  7. Iterative Magnetometer Calibration

    NASA Technical Reports Server (NTRS)

    Sedlak, Joseph

    2006-01-01

    This paper presents an iterative method for three-axis magnetometer (TAM) calibration that makes use of three existing utilities recently incorporated into the attitude ground support system used at NASA's Goddard Space Flight Center. The method combines attitude-independent and attitude-dependent calibration algorithms with a new spinning spacecraft Kalman filter to solve for biases, scale factors, nonorthogonal corrections to the alignment, and the orthogonal sensor alignment. The method is particularly well-suited to spin-stabilized spacecraft, but may also be useful for three-axis stabilized missions given sufficient data to provide observability.

  8. Vulcan: A deep-towed CSEM receiver

    NASA Astrophysics Data System (ADS)

    Constable, Steven; Kannberg, Peter K.; Weitemeyer, Karen

    2016-03-01

    We have developed a three-axis electric field receiver designed to be towed behind a marine electromagnetic transmitter for the purpose of mapping the electrical resistivity in the upper 1000 m of seafloor geology. By careful adjustment of buoyancy and the use of real-time monitoring of depth and altitude, we are able to deep-tow multiple receivers on arrays up to 1200 m long within 50 m of the seafloor, thereby obtaining good coupling to geology. The rigid body of the receiver is designed to reduce noise associated with lateral motion of flexible antennas during towing, and allows the measurement of the vertical electric field component, which modeling shows to be particularly sensitive to near-seafloor resistivity variations. The positions and orientations of the receivers are continuously measured, and realistic estimates of positioning errors can be used to build an error model for the data. During a test in the San Diego Trough, offshore California, inversions of the data were able to fit amplitude and phase of horizontal electric fields at three frequencies on three receivers to about 1% in amplitude and 1° in phase and vertical fields to about 5% in amplitude and 5° in phase. The geological target of the tests was a known cold seep and methane vent in 1000 m water depth, which inversions show to be associated with a 1 km wide resistor at a depth between 50 and 150 m below seafloor. Given the high resistivity (30 Ωm) and position within the gas hydrate stability field, we interpret this to be massive methane hydrate.

  9. Precessing Ferromagnetic Needle Magnetometer.

    PubMed

    Jackson Kimball, Derek F; Sushkov, Alexander O; Budker, Dmitry

    2016-05-13

    A ferromagnetic needle is predicted to precess about the magnetic field axis at a Larmor frequency Ω under conditions where its intrinsic spin dominates over its rotational angular momentum, Nℏ≫IΩ (I is the moment of inertia of the needle about the precession axis and N is the number of polarized spins in the needle). In this regime the needle behaves as a gyroscope with spin Nℏ maintained along the easy axis of the needle by the crystalline and shape anisotropy. A precessing ferromagnetic needle is a correlated system of N spins which can be used to measure magnetic fields for long times. In principle, by taking advantage of rapid averaging of quantum uncertainty, the sensitivity of a precessing needle magnetometer can far surpass that of magnetometers based on spin precession of atoms in the gas phase. Under conditions where noise from coupling to the environment is subdominant, the scaling with measurement time t of the quantum- and detection-limited magnetometric sensitivity is t^{-3/2}. The phenomenon of ferromagnetic needle precession may be of particular interest for precision measurements testing fundamental physics.

  10. Optically transduced MEMS magnetometer

    DOEpatents

    Nielson, Gregory N; Langlois, Eric

    2014-03-18

    MEMS magnetometers with optically transduced resonator displacement are described herein. Improved sensitivity, crosstalk reduction, and extended dynamic range may be achieved with devices including a deflectable resonator suspended from the support, a first grating extending from the support and disposed over the resonator, a pair of drive electrodes to drive an alternating current through the resonator, and a second grating in the resonator overlapping the first grating to form a multi-layer grating having apertures that vary dimensionally in response to deflection occurring as the resonator mechanically resonates in a plane parallel to the first grating in the presence of a magnetic field as a function of the Lorentz force resulting from the alternating current. A plurality of such multi-layer gratings may be disposed across a length of the resonator to provide greater dynamic range and/or accommodate fabrication tolerances.

  11. Large Array SQUID Magnetometer for NDE

    DTIC Science & Technology

    1993-04-27

    responsible for the magnetic precursor to plastic flow in ferromagnetic materials. --Determine how the magnetic precursor correlates with Barkhausen noise...Demonstrate the multiple-channel SQUIDs can localize the sites in the sample where individual stress-induced Barkhausen jumps are occurring. 1Il

  12. Miniature Laser Magnetometer

    NASA Technical Reports Server (NTRS)

    Slocum, Robert; Brown, Andy

    2011-01-01

    A conceptual design has been developed for a miniature laser magnetometer (MLM) that will measure the scalar magnitude and vector components of near-Earth magnetic fields. The MLM incorporates a number of technical innovations to achieve high-accuracy and high-resolution performance while significantly reducing the size of the laser-pumped helium magnetometer for use on small satellites and unmanned aerial vehicles (UAVs). and electronics sections that has the capability of measuring both the scalar magnetic field magnitude and the vector magnetic field components. Further more, the high-accuracy scalar measurements are used to calibrate and correct the vector component measurements in order to achieve superior vector accuracy and stability. The correction algorithm applied to the vector components for calibration and the same cell for vector and scalar measurements are major innovations. The separate sensor and electronics section of the MLM instrument allow the sensor to be installed on a boom or otherwise located away from electronics and other noisy magnetic components. The MLM s miniaturization will be accomplished through the use of advanced miniaturized components and packaging methods for the MLM sensor and electronics. The MLM conceptual design includes three key innovations. The first is a new non-magnetic laser package that will allow the placement of the laser pump source near the helium cell sensing elements. The second innovation is the design of compact, nested, triaxial Braunbek coils used in the vector measurements that reduce the coil size by a factor of two compared to existing Helmholtz coils with similar field-generation performance. The third innovation is a compact sensor design that reduces the sensor volume by a factor of eight compared to MLM s predecessor.

  13. 78 FR 49543 - Towing Safety Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-14

    ... SECURITY Coast Guard Towing Safety Advisory Committee AGENCY: Coast Guard, DHS. ACTION: Committee Management; Notice of Federal Advisory Committee Meeting. SUMMARY: The Towing Safety Advisory Committee (TSAC... related to shallow draft inland, coastal waterway navigation and towing safety. The meetings will be...

  14. Magnetoencephalography with a two-color pump probe atomic magnetometer.

    SciTech Connect

    Johnson, Cort N.

    2010-07-01

    The authors have detected magnetic fields from the human brain with a compact, fiber-coupled rubidium spin-exchange-relaxation-free magnetometer. Optical pumping is performed on the D1 transition and Faraday rotation is measured on the D2 transition. The beams share an optical axis, with dichroic optics preparing beam polarizations appropriately. A sensitivity of <5 fT/{radical}Hz is achieved. Evoked responses resulting from median nerve and auditory stimulation were recorded with the atomic magnetometer. Recordings were validated by comparison with those taken by a commercial magnetoencephalography system. The design is amenable to arraying sensors around the head, providing a framework for noncryogenic, whole-head magnetoencephalography.

  15. Electromagnetic induction imaging with a radio-frequency atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Deans, Cameron; Marmugi, Luca; Hussain, Sarah; Renzoni, Ferruccio

    2016-03-01

    We report on a compact, tunable, and scalable to large arrays imaging device, based on a radio-frequency optically pumped atomic magnetometer operating in magnetic induction tomography modality. Imaging of conductive objects is performed at room temperature, in an unshielded environment and without background subtraction. Conductivity maps of target objects exhibit not only excellent performance in terms of shape reconstruction but also demonstrate detection of sub-millimetric cracks and penetration of conductive barriers. The results presented here demonstrate the potential of a future generation of imaging instruments, which combine magnetic induction tomography and the unmatched performance of atomic magnetometers.

  16. Lunar surface magnetometer design review

    NASA Technical Reports Server (NTRS)

    1970-01-01

    Design and fabrication parameters of a lunar surface magnetometer are discussed. Drawings and requirements for mechanical design, electronic packaging design, thermal design, quality assurance and systems testing are included.

  17. Characteristics and performance of an intensity-modulated optically pumped magnetometer in comparison to the classical M(x) magnetometer.

    PubMed

    Schultze, Volkmar; Ijsselsteijn, Rob; Scholtes, Theo; Woetzel, Stefan; Meyer, Hans-Georg

    2012-06-18

    We compare the performance of two methods for the synchronization of the atomic spins in optically pumped magnetometers: intensity modulation of the pump light and the classical M(x) method using B(1) field modulation. Both techniques use the same set-up and measure the resulting features of the light after passing a micro-fabricated Cs cell. The intensity-modulated pumping shows several advantages: better noise-limited magnetic field sensitivity, misalignment between pumping and spin synchronization is excluded, and magnetometer arrays without any cross-talk can be easily set up.

  18. Optical Magnetometer Incorporating Photonic Crystals

    NASA Technical Reports Server (NTRS)

    Kulikov, Igor; Florescu, Lucia

    2007-01-01

    According to a proposal, photonic crystals would be used to greatly increase the sensitivities of optical magnetometers that are already regarded as ultrasensitive. The proposal applies, more specifically, to a state-of-the-art type of quantum coherent magnetometer that exploits the electromagnetically-induced-transparency (EIT) method for determining a small change in a magnetic field indirectly via measurement of the shift, induced by that change, in the hyperfine levels of resonant atoms exposed to the field.

  19. Magnetometer on Lunar Surface

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Sitting on the lunar surface, this magnetometer provided new data on the Moon's magnetic field. This was one of the instruments used during the Apollo 12 mission. The second manned lunar landing mission, Apollo 12 launched from launch pad 39-A at Kennedy Space Center in Florida on November 14, 1969 via a Saturn V launch vehicle. The Saturn V vehicle was developed by the Marshall Space Flight Center (MSFC) under the direction of Dr. Wernher von Braun. Aboard Apollo 12 was a crew of three astronauts: Alan L. Bean, pilot of the Lunar Module (LM), Intrepid; Richard Gordon, pilot of the Command Module (CM), Yankee Clipper; and Spacecraft Commander Charles Conrad. The LM, Intrepid, landed astronauts Conrad and Bean on the lunar surface in what's known as the Ocean of Storms while astronaut Richard Gordon piloted the CM, Yankee Clipper, in a parking orbit around the Moon. Lunar soil activities included the deployment of the Apollo Lunar Surface Experiments Package (ALSEP), finding the unmanned Surveyor 3 that landed on the Moon on April 19, 1967, and collecting 75 pounds (34 kilograms) of rock samples. Apollo 12 safely returned to Earth on November 24, 1969.

  20. Aircraft towing feasibility study. Final report

    SciTech Connect

    Not Available

    1980-09-01

    Energy costs and availability are major concerns in most parts of the world. Many ways of increasing energy supply and reducing consumption are being proposed and investigated. One that holds considerable promise is the extended towing of aircraft between airport runways and terminal gate areas with engines shut down. This study provides a preliminary assessment of the constraints on and feasibility of extended aircraft towing. Past aircraft towing experience and the state-of-the-art in towing equipment are reviewed. Safety and operational concerns associated with aircraft towing are identified, and the benefits and costs of implementing aircraft towing at 20 major US airports are analyzed. It was concluded that extended aircraft towing is technically feasible and that substantial reductions in aircraft fuel consumption and air pollutant emissions can be achieved through its implementation. It was also concluded that, although capital and operating costs associated with towing would be increased, net savings could generally be attained at these airports. Because of the lack of past experience and the necessity of proving the cost effectiveness of the towing concept, a demonstration of the feasibility of large-scale aircraft towing is necessary. The study evaluates the suitability of the 20 study airports as potential demonstration sites and makes recommendations for the first demonstration project.

  1. Continuous, linearly intermixed fiber tows and composite molded article thereform

    NASA Technical Reports Server (NTRS)

    McMahon, Paul E. (Inventor); Chung, Tai-Shung (Inventor); Ying, Lincoln (Inventor)

    2000-01-01

    The instant invention involves a process used in preparing fibrous tows which may be formed into polymeric plastic composites. The process involves the steps of (a) forming a carbon fiber tow; (b) forming a thermoplastic polymeric fiber tow; (c) intermixing the two tows; and (d) withdrawing the intermixed tow for further use.

  2. A low energy electron magnetometer

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Wood, G. M., Jr.; Rayborn, G. H.; White, F. A.

    1979-01-01

    The concept of a highly sensitive magnetometer based on the deflection of low energy electron beams in magnetic fields is analyzed. Because of its extremely low mass and consequently high e/m ratio, a low energy electron is easily deflected in a magnetic field, thus providing a basis for very low field measurement. Calculations for a specific instrument design indicate that a low energy electron magnetometer (LEEM) can measure magnetic fields as low as 1000 nT. The anticipated performance of LEEM is compared with that of the existing high resolution magnetometers in selected applications. The fast response time of LEEM makes it especially attractive as a potential instrument for magnetic signature analysis in large engineering systems.

  3. Cryogenic High-Sensitivity Magnetometer

    NASA Technical Reports Server (NTRS)

    Day, Peter; Chui, Talso; Goodstein, David

    2005-01-01

    A proposed magnetometer for use in a cryogenic environment would be sensitive enough to measure a magnetic-flux density as small as a picogauss (10(exp -16) Tesla). In contrast, a typical conventional flux-gate magnetometer cannot measure a magnetic-flux density smaller that about 1 microgauss (10(exp -10) Tesla). One version of this device, for operation near the low end of the cryogenic temperature range, would include a piece of a paramagnetic material on a platform, the temperature of which would be controlled with a periodic variation. The variation in temperature would be measured by use of a conventional germanium resistance thermometer. A superconducting coil would be wound around the paramagnetic material and coupled to a superconducting quantum interference device (SQUID) magnetometer.

  4. Towed Twin-Fuselage Glider Launch System (CGI Animation)

    NASA Video Gallery

    The towed glider is an element of the novel rocket-launching concept of the Towed Glider Air-Launch System (TGALS). The TGALS demonstration’s goal is to provide proof-of-concept of a towed, airborn...

  5. Process for preparing tows from composite fiber blends

    NASA Technical Reports Server (NTRS)

    McMahon, Paul (Inventor); Chung, Tai-Shung (Inventor); Ying, Lincoln (Inventor)

    1989-01-01

    A continuous, substantially uniform tow useful in forming composite molded articles is prepared by forming a continuous tow of continuous carbon fibers, forming a continuous tow of thermoplastic polymer fibers to a selected width, uniformly and continuously spreading the carbon fiber two to a width that is essentially the same as the selected width for the thermoplastic polymer fiber tow, intermixing the tows intimately, uniformly and continuously, in a relatively tension-free state, and continuosuly withdrawing the intermixed tow.

  6. An optically modulated zero-field atomic magnetometer with suppressed spin-exchange broadening

    SciTech Connect

    Jiménez-Martínez, R.; Knappe, S.; Kitching, J.

    2014-04-15

    We demonstrate an optically pumped {sup 87}Rb magnetometer in a microfabricated vapor cell based on a zero-field dispersive resonance generated by optical modulation of the {sup 87}Rb ground state energy levels. The magnetometer is operated in the spin-exchange relaxation-free regime where high magnetic field sensitivities can be achieved. This device can be useful in applications requiring array-based magnetometers where radio frequency magnetic fields can induce cross-talk among adjacent sensors or affect the source of the magnetic field being measured.

  7. An optically modulated zero-field atomic magnetometer with suppressed spin-exchange broadening.

    PubMed

    Jiménez-Martínez, R; Knappe, S; Kitching, J

    2014-04-01

    We demonstrate an optically pumped (87)Rb magnetometer in a microfabricated vapor cell based on a zero-field dispersive resonance generated by optical modulation of the (87)Rb ground state energy levels. The magnetometer is operated in the spin-exchange relaxation-free regime where high magnetic field sensitivities can be achieved. This device can be useful in applications requiring array-based magnetometers where radio frequency magnetic fields can induce cross-talk among adjacent sensors or affect the source of the magnetic field being measured.

  8. Towed Subsurface Optical Communications Buoy

    NASA Technical Reports Server (NTRS)

    Stirbl, Robert C.; Farr, William H.

    2013-01-01

    The innovation allows critical, high-bandwidth submarine communications at speed and depth. This reported innovation is a subsurface optical communications buoy, with active neutral buoyancy and streamlined flow surface veins for depth control. This novel subsurface positioning for the towed communications buoy enables substantial reduction in water-absorption and increased optical transmission by eliminating the intervening water absorption and dispersion, as well as by reducing or eliminating the beam spread and the pulse spreading that is associated with submarine-launched optical beams.

  9. Eclipse - tow flight closeup and release

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This clip, running 15 seconds in length, shows the QF-106 'Delta Dart' gear down, with the tow rope secured to the attachment point above the aircraft nose. First there is a view looking back from the C-141A, then looking forward from the nose of the QF-106, and finally a shot of the aircraft being released from the tow rope. NASA Dryden Flight Research Center, Edwards, California, supported a Kelly Space and Technology, Inc. (KST)/U.S. Air Force project known as Eclipse, which demonstrated a reusable tow launch vehicle concept. The purpose of the project was to demonstrate a reusable tow launch vehicle concept that had been conceived and patented by KST. Kelly Space obtained a contract with the USAF Research Laboratory for the tow launch demonstration project under the Small Business Innovation Research (SBIR) program. The USAF SBIR contract included the modifications to turn the QF-106 into the Experimental Demonstrator #1 (EXD-01), and the C141A aircraft to incorporate the tow provisions to link the two aircraft, as well as conducting flight tests. The demonstration consisted of ground and flight tests. These tests included a Combined Systems Test of both airplanes joined by a tow rope, a towed taxi test, and six towed flights. The primary goal of the project was demonstrating the tow phase of the Eclipse concept using a scaled-down tow aircraft (C-141A) and a representative aerodynamically-shaped aircraft (QF-106A) as a launch vehicle. This was successfully accomplished. On December 20, 1997, NASA research pilot Mark Stucky flew a QF-106 on the first towed flight behind an Air Force C-141 in the joint Eclipse project with KST to demonstrate a reusable tow launch vehicle concept developed by KST. Kelly Space and Technology hoped to use the data from the tow tests to validate a tow-to-launch procedure for reusable space launch vehicles. Stucky flew six successful tow tests between December 1997 and February 6, 1998. On February 6, 1998, the sixth and final towed

  10. Design and analysis of miniature tri-axial fluxgate magnetometer

    NASA Astrophysics Data System (ADS)

    Zhi, Menghui; Tang, Liang; Qiao, Donghai

    2017-02-01

    The detection technology of weak magnetic field is widely used in Earth resource survey and geomagnetic navigation. Useful magnetic field information can be obtained by processing and analyzing the measurement data from magnetic sensors. A miniature tri-axial fluxgate magnetometer is proposed in this paper. This miniature tri-axial fluxgate magnetometer with ring-core structure has a dynamic range of the Earth’s field ±65,000 nT, resolution of several nT. It has three independent parts placed in three perpendicular planes for measuring three orthogonal magnetic field components, respectively. A field-programmable gate array (FPGA) is used to generate stimulation signal, analog-to-digital (A/D) convertor control signal, and feedback digital-to-analog (D/A) control signal. Design and analysis details are given to improve the dynamic range, sensitivity, resolution, and linearity. Our prototype was measured and compared with a commercial standard Magson fluxgate magnetometer as a reference. The results show that our miniature fluxgate magnetometer can follow the Magson’s change trend well. When used as a magnetic compass, our prototype only has ± 0.3∘ deviation compared with standard magnetic compass.

  11. Observational magnetometer calibration with the Hubble Space Telescope's new magnetometers

    NASA Astrophysics Data System (ADS)

    Broude, Sidney M.

    1995-05-01

    The two magnetometers recently replaced on the Hubble Space Telescope during the STS-61 Servicing Mission are now being used successfully for Coarse Attitude Determination during spacecraft vehicle safemode recovery operation. The magnetometer alignments relative to the spacecraft's vehicle's reference frame and the magnetic coupling of the sensors to the four magnetic torquer bars were determined. Coarse Attitude determination errors are now reduced to an average of 0.6 deg. Magnetometer Sensing System calibration and Coarse Attitude determination testing with the new calibration parameters is a geometrical problem. Telemetered earth magnetic field data was collected at twenty-six different vehicle attitudes. The spacecraft attitudes selected were distributed as widely apart as possible throughout the Geocentric Inertial Coordinate reference frame. It is also desirable to sample the Earth's magnetic field over as many different locations of the spacecraft's passage over the Earth as possible, within the limitation of the +/- 28.5 deg orbital inclination. A full range of magnetic moment outputs from the torquer bars needs to be sampled, +/- 3600 ampmeters squared, as well as data when the torquer bars have zero current. Graphic utilities were also developed to visually aid in optimizing the data collection process. Finally, a brief discussion of a method for collecting data for future calibrations is suggested.

  12. Observational magnetometer calibration with the Hubble Space Telescope's new magnetometers

    NASA Technical Reports Server (NTRS)

    Broude, Sidney M.

    1995-01-01

    The two magnetometers recently replaced on the Hubble Space Telescope during the STS-61 Servicing Mission are now being used successfully for Coarse Attitude Determination during spacecraft vehicle safemode recovery operation. The magnetometer alignments relative to the spacecraft's vehicle's reference frame and the magnetic coupling of the sensors to the four magnetic torquer bars were determined. Coarse Attitude determination errors are now reduced to an average of 0.6 deg. Magnetometer Sensing System calibration and Coarse Attitude determination testing with the new calibration parameters is a geometrical problem. Telemetered earth magnetic field data was collected at twenty-six different vehicle attitudes. The spacecraft attitudes selected were distributed as widely apart as possible throughout the Geocentric Inertial Coordinate reference frame. It is also desirable to sample the Earth's magnetic field over as many different locations of the spacecraft's passage over the Earth as possible, within the limitation of the +/- 28.5 deg orbital inclination. A full range of magnetic moment outputs from the torquer bars needs to be sampled, +/- 3600 ampmeters squared, as well as data when the torquer bars have zero current. Graphic utilities were also developed to visually aid in optimizing the data collection process. Finally, a brief discussion of a method for collecting data for future calibrations is suggested.

  13. Analysis of Vertical Towed Body

    DTIC Science & Technology

    2006-01-10

    connectors to molded wet cables or swage locks to oil-filled cables. The wet cable decision is pending. Figure 12 – Source Array Center Mounting...Final decision on the source array weight. A few days after the meeting, a decision was mad to use a tungsten center mass in the array. The...oil-filled cables to be fed directly from the PV to the array via simple swage -lock penetrators. This will eliminate the need for bulky wet

  14. Controlling iceberg roll/stability during towing around drillships

    SciTech Connect

    Benedict, C.P.; Lewis, J.C.; Dinn, G.J.; Learning, F.R.

    1981-01-01

    Field iceberg survey data were collected and on the basis of Lagrangian computer analysis, a large sample of simulated bergs were towed from random stable floating positions. This paper presents: the results on instrumenting iceberg tow forces on the Aquitaine site during the 1980 drilling program, and an operational procedure for predicting critical tow forces on the basis of pre-tow surveys.

  15. CDSM - A New Scalar Magnetometer

    NASA Astrophysics Data System (ADS)

    Pollinger, Andreas; Lammegger, Roland; Magnes, Werner; Ellmeier, Michaela; Baumjohann, Wolfgang; Windholz, Laurentius

    2010-05-01

    There are potential advantages of flying a magnetometer sensor suite combining a vector fluxgate with a scalar absolute sensor. Absolute sensors offer superior stability over temperature and time, lower intrinsic noise and offset-free measurements; the latter is very useful for fluxgate calibration on a 3-axis stabilized spacecraft. A space-adapted design of a new type of scalar magnetometer, called Coupled Dark State Magnetometer (CDSM), is under development jointly by the Institute of Experimental Physics of the Graz University of Technology and the Space Research Institute of the Austrian Academy of Sciences. The CDSM is based on two-photon spectroscopy of free alkali atoms using a multi chromatic laser field. The measurement is made completely independent of the sensor temperature by a clever coupling of several coherent population trapping resonances. The CDSM promises a less resource-demanding instrument design (500g, 1W) compared to previously flown scalar magnetometers. A significant advantage is the fact that the extended measurement range of 7 decades is covered by only one sensor cell filled with Rubidium atoms (and a buffer gas), making the sensor core small and compact. Neither a radio frequency-based excitation at the sensor unit (150g) is needed for the operation, nor is it necessary to implement motor driven moving parts or a double cell unit in order to guarantee isotropic measurements like for other scalar sensors. A noise floor of 70pTrms/√Hz was measured in a first configuration. It is worth to mention that there is no 1/f noise below the implemented corner frequency of 3Hz. By changing from Rubidium D2 to D1 excitation line we are able to reduce the noise by a factor of 10 to 7pT. The technology readiness level of the CDSM is 3 at the moment and it shall reach level 5 (breadboard validation in relevant environment) by beginning of 2011.

  16. HTS magnetometers for fetal magnetocardiography.

    PubMed

    Li, Z; Wakai, R T; Paulson, D N; Schwartz, B

    2004-11-30

    High temperature superconducting (HTS) SQUID sensors have adequate magnetic field sensitivity for adult magnetocardiography (MCG) measurements, but it remains to be seen how well they perform for fetal MCG (fMCG), where the heart signals are typically ten times smaller than the adult signals. In this study, we assess the performance of a prototype HTS SQUID system; namely, a three-SQUID gradiometer formed from three vertically-aligned HTS dc-SQUID magnetometers integrated into a fiberglass liquid nitrogen dewar of diameter 12.5 cm and height 30 cm. Axial gradiometers with short or long baseline, as well as a second order gradiometer, can be formed out of these magnetometers via electronic subtraction. The calibrated magnetometer sensitivities at 1 kHz are 109 fT/square root of Hz, 155 fT/square root of Hz and 51 fT/square root of Hz. Direct comparison is made between the HTS SQUID system and a LTS SQUID system by making recordings with both systems during the same session on adult and fetal subjects. Although the fMCG could be resolved with the HTS SQUID system in most near-term subjects, the signal-to-noise ratio was relatively low and the system could not be operated outside of a shielded room.

  17. Magnetoencephalography with Optically Pumped Atomic Magnetometers

    NASA Astrophysics Data System (ADS)

    Schwindt, Peter; Colombo, Anthony; Jau, Yuan-Yu; Carter, Tony; Berry, Christopher; Young, Amber; McKay, Jim; Weisend, Michael

    2015-05-01

    We are working to develop a 36-channel array of optically pumped atomic magnetometers (AMs) to perform magnetoencephalography (MEG) with the goal of localizing magnetic sources within the human brain. The 36-channel array will consist of nine 4-channel sensor modules where the channels within each sensor will be spaced by 18 mm and each sensor will cover a 40 mm by 40 mm area of the head. In a previous 4-channel AM prototype, we demonstrated the measurement of evoked responses in both the auditory and somatosensory cortexes. This prototype had a 5 fT/Hz1/2 sensitivity. In the current version of the AM under development we are maintaining the previous sensitivity while implementing several improvements, including increasing the bandwidth from 20 Hz to more than 100 Hz, reducing the separation of the active volume of the AM from exterior of the sensor from 25 mm to 10 mm or less, and reducing the active sensor volume by a factor >10 to ~15 mm3. We will present results on the performance of our most recent AM prototype and progress toward developing a complete MEG system including a person-sized magnetic shield to provide a low-noise magnetic environment for MEG measurements.

  18. System Applies Polymer Powder To Filament Tow

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.; Snoha, John J.; Marchello, Joseph M.

    1993-01-01

    Polymer powder applied uniformly and in continuous manner. Powder-coating system applies dry polymer powder to continuous fiber tow. Unique filament-spreading technique, combined with precise control of tension on fibers in system, ensures uniform application of polymer powder to web of spread filaments. Fiber tows impregnated with dry polymer powders ("towpregs") produced for preform-weaving and composite-material-molding applications. System and process valuable to prepreg industry, for production of flexible filament-windable tows and high-temperature polymer prepregs.

  19. 14 CFR 25.509 - Towing loads.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... towing fittings and must act parallel to the ground. In addition— (1) A vertical load factor equal to 1.0...) A reaction with a maximum value equal to the vertical reaction must be applied at the axle of...

  20. 14 CFR 25.509 - Towing loads.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... towing fittings and must act parallel to the ground. In addition— (1) A vertical load factor equal to 1.0...) A reaction with a maximum value equal to the vertical reaction must be applied at the axle of...

  1. 14 CFR 25.509 - Towing loads.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... towing fittings and must act parallel to the ground. In addition— (1) A vertical load factor equal to 1.0...) A reaction with a maximum value equal to the vertical reaction must be applied at the axle of...

  2. 14 CFR 25.509 - Towing loads.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... towing fittings and must act parallel to the ground. In addition— (1) A vertical load factor equal to 1.0...) A reaction with a maximum value equal to the vertical reaction must be applied at the axle of...

  3. 14 CFR 25.509 - Towing loads.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... towing fittings and must act parallel to the ground. In addition— (1) A vertical load factor equal to 1.0...) A reaction with a maximum value equal to the vertical reaction must be applied at the axle of...

  4. Communication: Cargo towing by artificial swimmers

    NASA Astrophysics Data System (ADS)

    Debnath, Debajyoti; Ghosh, Pulak K.; Li, Yunyun; Marchesoni, Fabio; Li, Baowen

    2016-11-01

    An active swimmer can tow a passive cargo by binding it to form a self-propelling dimer. The orientation of the cargo relative to the axis of the active dimer's head is determined by the hydrodynamic interactions associated with the propulsion mechanism of the latter. We show how the tower-cargo angular configuration greatly influences the dimer's diffusivity and, therefore, the efficiency of the active swimmer as a micro-towing motor.

  5. Free-Flying Magnetometer Data System

    NASA Technical Reports Server (NTRS)

    Blaes, B.; Javadi, H.; Spencer, H.

    2000-01-01

    The Free-Flying Magnetometer (FFM) is an autonomous "sensorcraft" developed at the Jet Propulsion Laboratory (JPL) for the Enstrophy sounding rocket mission. This mission was a collaborative project between the University of New Hampshire, Cornell University and JPL. The science goal of the mission was the study of current filamentation phenomena in the northern auroral region through multipoint measurements of magnetic field. The technical objective of the mission was the proof of concept of the JPL FFM design and the demonstration of an in-situ multipoint measurement technique employing many free-flying spacecraft. Four FFMs were successfully deployed from a sounding rocket launched from Poker Flats, Alaska on February 11, 1999. These hockey-puck-sized (80 mm diameter, 38 mm. height, 250 gram mass) free flyers each carry a miniature 3-axis flux-gate magnetometer that output +/- 2 V signals corresponding to a +/- 60,000 nT measurement range for each axis. The FFM uses a synchronized four-channel Sigma(Delta) Analog-to-Digital Converter (ADC) having a dynamic range of +/- 2.5V and converting at a rate of 279 samples/second/channel. Three channels are used to digitize the magnetometer signals to 17-bit (1.144 nT/bit) resolution. The fourth ADC channel is multiplexed for system monitoring of four temperature sensors and two battery voltages. The FFM also contains two sun sensors, a laser diode which emits a fan-shaped beam, a miniature S-band transmitter for direct communication to the ground station antennas, an ultra-stable Temperature Compensated Crystal Oscillator (TCXO) clock, an integrated data subsystem implemented in a Field-Programmable Gate Array (FPGA), a 4 Mbit Static Random Access Memory (SRAM) for data storage and Lithium Thionyl Chloride batteries for power. Communicating commands to the FFM prior to deployment is achieved with an infrared (IR) link. The FFM IR receiver responds to 9-bit pulse coded signals that are generated by an IR Light Emitting

  6. Computational Analysis of Towed Ballute Interactions

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.; Anderson, Brian P.

    2002-01-01

    A ballute (balloon-parachute) is an inflatable, aerodynamic drag device for application to planetary entry vehicles. Ballutes may be directly attached to a vehicle, increasing its cross-sectional area upon inflation, or towed behind the vehicle as a semi-independent device that can be quickly cut free when the requisite change in velocity is achieved. The aerothermodynamics of spherical and toroidal towed ballutes are considered in the present study. A limiting case of zero towline length (clamped system) is also considered. A toroidal system can be designed (ignoring influence of the tethers) such that all flow processed by the bow shock of the towing spacecraft passes through the hole in the toroid. For a spherical ballute, towline length is a critical parameter that affects aeroheating on the ballute being towed through the spacecraft wake. In both cases, complex and often unsteady interactions ensue in which the spacecraft and its wake resemble an aero spike situated in front of the ballute. The strength of the interactions depends upon system geometry and Reynolds number. We show how interactions may envelope the base of the towing spacecraft or impinge on the ballute surface with adverse consequences to its thermal protection system. Geometric constraints to minimize or eliminate such adverse interactions are discussed. The towed, toroidal system and the clamped, spherical system show greatest potential for a baseline design approach.

  7. Construction of an alternating gradient magnetometer

    NASA Technical Reports Server (NTRS)

    Garland, Michael M.

    1988-01-01

    A magnetometer is described which was constructed to facilitate the study and characterization of the magnetic properties of high transition temperature superconductors. This instrument was used to measure the dc magnetic susceptibility of several superconducting compounds as a function of temperature. The construction of the magnetometer and the operating parameters are discussed in detail.

  8. A Complete Cubesat Magnetometer System Project

    NASA Technical Reports Server (NTRS)

    Zesta, Eftyhia

    2014-01-01

    The objective of this work is to provide the center with a fully tested, flexible, low cost, miniaturized science magnetometer system applicable to small satellite programs, like Cubesats, and to rides of opportunity that do not lend themselves to the high integration costs a science magnetometer on a boom necessitates.

  9. High sensitivity optically pumped quantum magnetometer.

    PubMed

    Tiporlini, Valentina; Alameh, Kamal

    2013-01-01

    Quantum magnetometers based on optical pumping can achieve sensitivity as high as what SQUID-based devices can attain. In this paper, we discuss the principle of operation and the optimal design of an optically pumped quantum magnetometer. The ultimate intrinsic sensitivity is calculated showing that optimal performance of the magnetometer is attained with an optical pump power of 20 μW and an operation temperature of 48°C. Results show that the ultimate intrinsic sensitivity of the quantum magnetometer that can be achieved is 327 fT/Hz(½) over a bandwidth of 26 Hz and that this sensitivity drops to 130 pT/Hz(½) in the presence of environmental noise. The quantum magnetometer is shown to be capable of detecting a sinusoidal magnetic field of amplitude as low as 15 pT oscillating at 25 Hz.

  10. Three axis vector atomic magnetometer utilizing polarimetric technique

    NASA Astrophysics Data System (ADS)

    Pradhan, Swarupananda

    2016-09-01

    The three axis vector magnetic field measurement based on the interaction of a single elliptically polarized light beam with an atomic system is described. The magnetic field direction dependent atomic responses are extracted by the polarimetric detection in combination with laser frequency modulation and magnetic field modulation techniques. The magnetometer geometry offers additional critical requirements like compact size and large dynamic range for space application. Further, the three axis magnetic field is measured using only the reflected signal (one polarization component) from the polarimeter and thus can be easily expanded to make spatial array of detectors and/or high sensitivity field gradient measurement as required for biomedical application.

  11. Three axis vector atomic magnetometer utilizing polarimetric technique.

    PubMed

    Pradhan, Swarupananda

    2016-09-01

    The three axis vector magnetic field measurement based on the interaction of a single elliptically polarized light beam with an atomic system is described. The magnetic field direction dependent atomic responses are extracted by the polarimetric detection in combination with laser frequency modulation and magnetic field modulation techniques. The magnetometer geometry offers additional critical requirements like compact size and large dynamic range for space application. Further, the three axis magnetic field is measured using only the reflected signal (one polarization component) from the polarimeter and thus can be easily expanded to make spatial array of detectors and/or high sensitivity field gradient measurement as required for biomedical application.

  12. Four-channel optically pumped atomic magnetometer for magnetoencephalography.

    PubMed

    Colombo, Anthony P; Carter, Tony R; Borna, Amir; Jau, Yuan-Yu; Johnson, Cort N; Dagel, Amber L; Schwindt, Peter D D

    2016-07-11

    We have developed a four-channel optically pumped atomic magnetometer for magnetoencephalography (MEG) that incorporates a passive diffractive optical element (DOE). The DOE allows us to achieve a long, 18-mm gradiometer baseline in a compact footprint on the head. Using gradiometry, the sensitivities of the channels are < 5 fT/Hz1/2, and the 3-dB bandwidths are approximately 90 Hz, which are both sufficient to perform MEG. Additionally, the channels are highly uniform, which offers the possibility of employing standard MEG post-processing techniques. This module will serve as a building block of an array for magnetic source localization.

  13. Aerothermodynamic Analyses of Towed Ballutes

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.; Buck, Greg; Moss, James N.; Nielsen, Eric; Berger, Karen; Jones, William T.; Rudavsky, Rena

    2006-01-01

    A ballute (balloon-parachute) is an inflatable, aerodynamic drag device for application to planetary entry vehicles. Two challenging aspects of aerothermal simulation of towed ballutes are considered. The first challenge, simulation of a complete system including inflatable tethers and a trailing toroidal ballute, is addressed using the unstructured-grid, Navier-Stokes solver FUN3D. Auxiliary simulations of a semi-infinite cylinder using the rarefied flow, Direct Simulation Monte Carlo solver, DSV2, provide additional insight into limiting behavior of the aerothermal environment around tethers directly exposed to the free stream. Simulations reveal pressures higher than stagnation and corresponding large heating rates on the tether as it emerges from the spacecraft base flow and passes through the spacecraft bow shock. The footprint of the tether shock on the toroidal ballute is also subject to heating amplification. Design options to accommodate or reduce these environments are discussed. The second challenge addresses time-accurate simulation to detect the onset of unsteady flow interactions as a function of geometry and Reynolds number. Video of unsteady interactions measured in the Langley Aerothermodynamic Laboratory 20-Inch Mach 6 Air Tunnel and CFD simulations using the structured grid, Navier-Stokes solver LAURA are compared for flow over a rigid spacecraft-sting-toroid system. The experimental data provides qualitative information on the amplitude and onset of unsteady motion which is captured in the numerical simulations. The presence of severe unsteady fluid - structure interactions is undesirable and numerical simulation must be able to predict the onset of such motion.

  14. Nuclear quantum-assisted magnetometer

    NASA Astrophysics Data System (ADS)

    Häberle, Thomas; Oeckinghaus, Thomas; Schmid-Lorch, Dominik; Pfender, Matthias; de Oliveira, Felipe Fávaro; Momenzadeh, Seyed Ali; Finkler, Amit; Wrachtrup, Jörg

    2017-01-01

    Magnetic sensing and imaging instruments are important tools in biological and material sciences. There is an increasing demand for attaining higher sensitivity and spatial resolution, with implementations using a single qubit offering potential improvements in both directions. In this article we describe a scanning magnetometer based on the nitrogen-vacancy center in diamond as the sensor. By means of a quantum-assisted readout scheme together with advances in photon collection efficiency, our device exhibits an enhancement in signal to noise ratio of close to an order of magnitude compared to the standard fluorescence readout of the nitrogen-vacancy center. This is demonstrated by comparing non-assisted and assisted methods in a T1 relaxation time measurement.

  15. Noiseless coding for the magnetometer

    NASA Technical Reports Server (NTRS)

    Rice, Robert F.; Lee, Jun-Ji

    1987-01-01

    Future unmanned space missions will continue to seek a full understanding of magnetic fields throughout the solar system. Severely constrained data rates during certain portions of these missions could limit the possible science return. This publication investigates the application of universal noiseless coding techniques to more efficiently represent magnetometer data without any loss in data integrity. Performance results indicated that compression factors of 2:1 to 6:1 can be expected. Feasibility for general deep space application was demonstrated by implementing a microprocessor breadboard coder/decoder using the Intel 8086 processor. The Comet Rendezvous Asteroid Flyby mission will incorporate these techniques in a buffer feedback, rate-controlled configuration. The characteristics of this system are discussed.

  16. Nuclear quantum-assisted magnetometer.

    PubMed

    Häberle, Thomas; Oeckinghaus, Thomas; Schmid-Lorch, Dominik; Pfender, Matthias; de Oliveira, Felipe Fávaro; Momenzadeh, Seyed Ali; Finkler, Amit; Wrachtrup, Jörg

    2017-01-01

    Magnetic sensing and imaging instruments are important tools in biological and material sciences. There is an increasing demand for attaining higher sensitivity and spatial resolution, with implementations using a single qubit offering potential improvements in both directions. In this article we describe a scanning magnetometer based on the nitrogen-vacancy center in diamond as the sensor. By means of a quantum-assisted readout scheme together with advances in photon collection efficiency, our device exhibits an enhancement in signal to noise ratio of close to an order of magnitude compared to the standard fluorescence readout of the nitrogen-vacancy center. This is demonstrated by comparing non-assisted and assisted methods in a T1 relaxation time measurement.

  17. Optical fiber feedback SQUID magnetometer

    SciTech Connect

    Naito, S.; Sampei, Y.; Takahashi, T. )

    1989-04-01

    This paper describes an optical fiber feedback superconducting quantum interference device (SQUID) magnetometer which was developed to improve electromagnetic interference characteristics. The SQUID consists of an RF SQUID probe, an RF amplifier, two multimode fibers, and a SQUID control unit. Phase-locked pulse width modulation (PWM) was used to construct a flux locked loop (FLL) circuit in the SQUID control unit. The operation of the optical fiber feedback SQUID is stable when a common mode voltage of ac 100 V/50 Hz is applied. It has an energy resolution of 1 x 10/sup -28/ J/Hz. This paper also describes the measurement of an auditory evoked field from the human brain in a magnetically shielded room using the fiber feedback SQUID with a gradiometer type pickup coil.

  18. 10. VIEW NORTH FROM FLOOR LEVEL OF DRYDOCK OF TOW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. VIEW NORTH FROM FLOOR LEVEL OF DRY-DOCK OF TOW TANK No. 1, WITH TORPEDO BODY BEING PREPARED FOR TANK TESTING. - NASA Langley Research Center, Seaplane Towing Channel, 108 Andrews Street, Hampton, Hampton, VA

  19. 77 FR 49002 - Towing Safety Advisory Committee; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-15

    ... revision of NVIC 1-95, Voluntary Training Standards for Entry-Level Personnel on Towing Industry Vessels... revision of NVIC 1-95, Voluntary Training Standards for Entry-Level Personnel on Towing Industry...

  20. Efficiency of cargo towing by a microswimmer.

    PubMed

    Raz, O; Leshansky, A M

    2008-05-01

    We study the properties of an arbitrary microswimmer towing a passive load through a viscous liquid. The simple close-form expression for the dragging efficiency of a microswimmer dragging a distant load is found, and the approximation for finite mutual proximity is derived. We show that, while the swimmer can be arbitrarily efficient, the dragging efficiency is always bounded from above. It is also demonstrated, that opposite to Purcell's assumption [E. M. Purcell, Proc. Natl. Acad. Sci. U.S.A. 94, 11307 (1997)], the hydrodynamic coupling can "help" the propeller to tow the load. We support our conclusions by rigorous numerical calculations for the rotary swimmer, towing a spherical cargo positioned at a finite distance.

  1. Efficiency of cargo towing by a microswimmer

    NASA Astrophysics Data System (ADS)

    Raz, O.; Leshansky, A. M.

    2008-05-01

    We study the properties of an arbitrary microswimmer towing a passive load through a viscous liquid. The simple close-form expression for the dragging efficiency of a microswimmer dragging a distant load is found, and the approximation for finite mutual proximity is derived. We show that, while the swimmer can be arbitrarily efficient, the dragging efficiency is always bounded from above. It is also demonstrated, that opposite to Purcell’s assumption [E. M. Purcell, Proc. Natl. Acad. Sci. U.S.A. 94, 11307 (1997)], the hydrodynamic coupling can “help” the propeller to tow the load. We support our conclusions by rigorous numerical calculations for the rotary swimmer, towing a spherical cargo positioned at a finite distance.

  2. Customized ATP towpreg. [Automated Tow Placement

    NASA Technical Reports Server (NTRS)

    Sandusky, Donald A.; Marchello, Joseph M.; Baucom, Robert M.; Johnston, Norman J.

    1992-01-01

    Automated tow placement (ATP) utilizes robotic technology to lay down adjacent polymer-matrix-impregnated carbon fiber tows on a tool surface. Consolidation and cure during ATP requires that void elimination and polymer matrix adhesion be accomplished in the short period of heating and pressure rolling that follows towpreg ribbon placement from the robot head to the tool. This study examined the key towpreg ribbon properties and dimensions which play a significant role in ATP. Analysis of the heat transfer process window indicates that adequate heating can be achieved at lay down rates as high as 1 m/sec. While heat transfer did not appear to be the limiting factor, resin flow and fiber movement into tow lap gaps could be. Accordingly, consideration was given to towpreg ribbon having uniform yet non-rectangular cross sections. Dimensional integrity of the towpreg ribbon combined with customized ribbon architecture offer great promise for processing advances in ATP of high performance composites.

  3. A High Bandwidth Optically Pumped Atomic Magnetometer

    NASA Astrophysics Data System (ADS)

    Jimenez-Martinez, Ricardo; Griffith, Clark W.; Knappe, Svenja; Kitching, John

    2009-10-01

    The measurement of magnetic fields has proved to be relevant in many realms of basic and applied science. Among the different techniques to measure magnetic fields, that of optically pumped atomic magnetometers has experienced considerable attention recently. This interest stems from the development of atomic magnetometers that achieve sensitivities in the sub-femto Tesla range, and the development of techniques that enable highly miniaturized, compact, with low-power consumption magnetometers. The sensitivity and bandwidth of atomic magnetometers is set by their spin coherence time, which in most magnetometers is limited by atomic collisions. Better sensitivities are achieved by suppressing the spin decoherence introduced by atomic collisions, but at a cost of lower bandwidth. For certain applications, a magnetometer with a high bandwidth is useful. Here we present a technique to achieve high bandwidth while preserving high sensitivity. We support the technique with table-top measurements showing that a bandwidth of 10 KHz and sensitivity of 10 pTrms/(Hz)^1/2 can be achieved in a compact device. We also highlight the current development of a miniature atomic magnetometer based on this technique.

  4. 77 FR 31631 - Towing Safety Advisory Committee; Vacancies

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-29

    ... SECURITY Coast Guard Towing Safety Advisory Committee; Vacancies AGENCY: Coast Guard, DHS. ACTION: Request for applications. SUMMARY: The Coast Guard seeks applications for membership on the Towing Safety... shallow-draft inland and coastal waterway navigation and towing safety. DATES: Applicants should submit...

  5. 49 CFR 392.63 - Towing or pushing loaded buses.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false Towing or pushing loaded buses. 392.63 Section 392... COMMERCIAL MOTOR VEHICLES Prohibited Practices § 392.63 Towing or pushing loaded buses. No disabled bus with passengers aboard shall be towed or pushed; nor shall any person use or permit to be used a bus...

  6. 49 CFR 392.63 - Towing or pushing loaded buses.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 5 2012-10-01 2012-10-01 false Towing or pushing loaded buses. 392.63 Section 392... COMMERCIAL MOTOR VEHICLES Prohibited Practices § 392.63 Towing or pushing loaded buses. No disabled bus with passengers aboard shall be towed or pushed; nor shall any person use or permit to be used a bus...

  7. 49 CFR 392.63 - Towing or pushing loaded buses.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 5 2013-10-01 2013-10-01 false Towing or pushing loaded buses. 392.63 Section 392... COMMERCIAL MOTOR VEHICLES Prohibited Practices § 392.63 Towing or pushing loaded buses. No disabled bus with passengers aboard shall be towed or pushed; nor shall any person use or permit to be used a bus...

  8. 49 CFR 392.63 - Towing or pushing loaded buses.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 5 2011-10-01 2011-10-01 false Towing or pushing loaded buses. 392.63 Section 392... COMMERCIAL MOTOR VEHICLES Prohibited Practices § 392.63 Towing or pushing loaded buses. No disabled bus with passengers aboard shall be towed or pushed; nor shall any person use or permit to be used a bus...

  9. 49 CFR 392.63 - Towing or pushing loaded buses.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Towing or pushing loaded buses. 392.63 Section 392... COMMERCIAL MOTOR VEHICLES Prohibited Practices § 392.63 Towing or pushing loaded buses. No disabled bus with passengers aboard shall be towed or pushed; nor shall any person use or permit to be used a bus...

  10. Theodolite-borne vector Overhauser magnetometer: DIMOVER

    NASA Astrophysics Data System (ADS)

    Sapunov, V.; Rasson, J.; Denisov, A.; Saveliev, D.; Kiselev, S.; Denisova, O.; Podmogov, Y.; Khomutov, S.

    2006-06-01

    This report covers results of the long-term research directed at developing an absolute vector proton magnetometer based on the switching of bias magnetic fields. The distinctive feature is the attempt of the installation of a miniature Overhauser sensor and optimized Garret solenoid directly on the telescope of the theodolite. Thus this design (Declination Inclination Modulus Overhauser magnetometer: DIMOVER) will complement the universally recognised DIflux absolute device by adding full vector measurement capability. Preliminary designs, which also can be interesting to the experts in vector proton magnetometers, are presented.

  11. Magnetoencephalography with a two-color pump-probe, fiber-coupled atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Johnson, Cort; Schwindt, Peter D. D.; Weisend, Michael

    2010-12-01

    The authors have detected magnetic fields from the human brain with a compact, fiber-coupled rubidium spin-exchange-relaxation-free magnetometer. Optical pumping is performed on the D1 transition and Faraday rotation is measured on the D2 transition. The beams share an optical axis, with dichroic optics preparing beam polarizations appropriately. A sensitivity of <5 fT/√Hz is achieved. Evoked responses resulting from median nerve and auditory stimulation were recorded with the atomic magnetometer. Recordings were validated by comparison with those taken by a commercial magnetoencephalography system. The design is amenable to arraying sensors around the head, providing a framework for noncryogenic, whole-head magnetoencephalography.

  12. X-34 and HSTV tow vehicle on lakebed prior to tow test

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Following initial captive flight tests last year at NASA's Dryden Flight Research Center, Edwards Air Force Base, California, the X-34 technology demonstrator began a new series of tests last week in which it is being towed behind a semi-truck and released to coast on the Edwards dry lakebed. On July 20, 2000, it was towed and released twice at speeds of five and 10 miles per hour. On July 24, 2000, it was towed and released twice at 10 and 30 miles per hour. Twelve tests are planned during which the X-34 will be towed for distances up to 10,000 feet and released at speeds up to 80 miles per hour. The test series is expected to last at least six weeks.

  13. SEADYN Analysis of a Tow Line for a High Altitude Towed Glider

    NASA Technical Reports Server (NTRS)

    Colozza, Anthony J.

    1996-01-01

    The concept of using a system, consisting of a tow aircraft, glider and tow line, which would enable subsonic flight at altitudes above 24 km (78 kft) has previously been investigated. The preliminary results from these studies seem encouraging. Under certain conditions these studies indicate the concept is feasible. However, the previous studies did not accurately take into account the forces acting on the tow line. Therefore in order to investigate the concept further a more detailed analysis was needed. The code that was selected was the SEADYN cable dynamics computer program which was developed at the Naval Facilities Engineering Service Center. The program is a finite element based structural analysis code that was developed over a period of 10 years. The results have been validated by the Navy in both laboratory and at actual sea conditions. This code was used to simulate arbitrarily-configured cable structures subjected to excitations encountered in real-world operations. The Navy's interest was mainly for modeling underwater tow lines, however the code is also usable for tow lines in air when the change in fluid properties is taken into account. For underwater applications the fluid properties are basically constant over the length of the tow line. For the tow aircraft/glider application the change in fluid properties is considerable along the length of the tow line. Therefore the code had to be modified in order to take into account the variation in atmospheric properties that would be encountered in this application. This modification consisted of adding a variable density to the fluid based on the altitude of the node being calculated. This change in the way the code handled the fluid density had no effect on the method of calculation or any other factor related to the codes validation.

  14. Towed Articulated Housing For Geophysical Measurements

    NASA Technical Reports Server (NTRS)

    Burke, James D.; Cantrell, James

    1992-01-01

    Snakelike articulated string of rigid shells towed by helicopter, boat, kite or balloon, carries scientific instruments over land and sea surfaces. Nested shells connected to internal chain by bolt covered by preceding cone. String articulates readily to negotiate obstacles, but locally stiff to lie across a narrow crevasse.

  15. Sensitivity of double-resonance alignment magnetometers

    SciTech Connect

    Di Domenico, Gianni; Saudan, Herve; Bison, Georg; Knowles, Paul; Weis, Antoine

    2007-08-15

    We present an experimental study of the intrinsic magnetometric sensitivity of an optical or rf-frequency double-resonance magnetometer in which linearly polarized laser light is used in the optical pumping and detection processes. We show that a semiempirical model of the magnetometer can be used to describe the magnetic resonance spectra. Then, we present an efficient method to predict the optimum operating point of the magnetometer, i.e., the light power and rf Rabi frequency providing maximum magnetometric sensitivity. Finally, we apply the method to investigate the evolution of the optimum operating point with temperature. The method is very efficient to determine relaxation rates and thus allowed us to determine the three collisional disalignment cross sections for the components of the alignment tensor. Both first and second harmonic signals from the magnetometer are considered and compared.

  16. Advanced helium magnetometer for space applications

    NASA Technical Reports Server (NTRS)

    Slocum, Robert E.

    1987-01-01

    The goal of this effort was demonstration of the concepts for an advanced helium magnetometer which meets the demands of future NASA earth orbiting, interplanetary, solar, and interstellar missions. The technical effort focused on optical pumping of helium with tunable solid state lasers. We were able to demonstrate the concept of a laser pumped helium magnetometer with improved accuracy, low power, and sensitivity of the order of 1 pT. A number of technical approaches were investigated for building a solid state laser tunable to the helium absorption line at 1083 nm. The laser selected was an Nd-doped LNA crystal pumped by a diode laser. Two laboratory versions of the lanthanum neodymium hexa-aluminate (LNA) laser were fabricated and used to conduct optical pumping experiments in helium and demonstrate laser pumped magnetometer concepts for both the low field vector mode and the scalar mode of operation. A digital resonance spectrometer was designed and built in order to evaluate the helium resonance signals and observe scalar magnetometer operation. The results indicate that the laser pumped sensor in the VHM mode is 45 times more sensitive than a lamp pumped sensor for identical system noise levels. A study was made of typical laser pumped resonance signals in the conventional magnetic resonance mode. The laser pumped sensor was operated as a scalar magnetometer, and it is concluded that magnetometers with 1 pT sensitivity can be achieved with the use of laser pumping and stable laser pump sources.

  17. Noise characteristics research of Overhauser magnetometer sensor

    NASA Astrophysics Data System (ADS)

    Liu, Tala; Gu, Lingjia; Zhang, Shuang; Fu, Haoyang

    2015-09-01

    Overhauser magnetometer, a kind of weak-magnetic measurement system based on the Overhauser effect, has been widely used in satellite magnetic survey, aeromagnetic survey and other engineering and environmental applications. Overhauser magnetometer plays an important role in the application of magnetic field measurement for its advantages of low power consumption and high accuracy. Weak field magnetic resonance is usually limited by the signal to noise ratio (SNR). In order to improve the SNR of Overhauser magnetometer, noise characteristics of Overhauser magnetometer sensor are investigated in this paper. A background noise model of Overhauser magnetometer sensor is presented. The calculated results indicate that the noise power spectral density shows a band-limited white noise characteristic. The maximum value of the noise power spectral density observed at the resonant frequency. The measured results coincide with the calculated results. The correlation between the SNR and the matched resistance is investigated by using the noise model. The calculated results demonstrate that large matched resistance is beneficial to improve the SNR of the sensor. When matched resistance is larger than 100kΩ, the SNR tends to be a constant. On the premise of stability, the sensor will achieve the optimal SNR when the matched resistance is around 100kΩ. This investigation is beneficial to improve noise performance of Overhauser magnetometer sensor.

  18. The AUTUMNX magnetometer meridian chain in Québec, Canada

    NASA Astrophysics Data System (ADS)

    Connors, Martin; Schofield, Ian; Reiter, Kyle; Chi, Peter J.; Rowe, Kathryn M.; Russell, Christopher T.

    2016-01-01

    The AUTUMNX magnetometer array consists of 10 THEMIS-class ground-based magnetometers deployed to form a meridian chain on the eastern coast of Hudson Bay in eastern Canada, a second partial chain one hour of magnetic local time further east, and one magnetometer at an intermediate midlatitude site. These instruments, augmented by those of other arrays, permit good latitudinal coverage through the auroral zone on two meridians, some midlatitude coverage, and detection of magnetic field changes near the sensitive infrastructure of the Hydro-Québec power grid. Further, they offer the possibility for conjugate studies with Antarctica and the GOES East geosynchronous satellite, and complement the Chinese International Space Weather Meridian Circle Program. We examine current world distribution of magnetometers to show the need for AUTUMNX, and describe the instrumentation which allows near-real-time monitoring. We present magnetic inversion results for the disturbed day February 17, 2015, which showed classic signatures of the substorm current wedge, and developed into steady magnetospheric convection (SMC). For a separate event later that day, we examine a large and rapid magnetic field change event associated with an unusual near-Earth transient. We show GOES East conjugacy for these events.

  19. Magnetic induction imaging with optical atomic magnetometers: towards applications to screening and surveillance

    NASA Astrophysics Data System (ADS)

    Marmugi, Luca; Hussain, Sarah; Deans, Cameron; Renzoni, Ferruccio

    2015-10-01

    We propose a new approach, based on optical atomic magnetometers and magnetic induction tomography (MIT), for remote and non-invasive detection of conductive targets. Atomic magnetometers overcome the main limitations of conventional MIT instrumentation, in particular their poor low-frequency sensitivity, their large size and their limited scalability. Moreover, atomic magnetometers have been proven to reach extremely high sensitivities, with an improvement of up to 7 orders of magnitude in the 50 MHz to DC band, with respect to a standard pick-up coil of the same size. In the present scheme, an oscillating magnetic field induces eddy currents in a conductive target and laser-pumped atomic magnetometers, either stand-alone or in an array, detect the response of the objects. A phase-sensitive detection scheme rejects the background, allowing remote detection of the secondary field and, thus, mapping of objects, hidden in cargos, underwater or underground. The potential for extreme sensitivity, miniaturization, dynamic range and array operation paves the way to a new generation of non-invasive, active detectors for surveillance, as well as for real-time cargo screening.

  20. Commercial-off-the-Shelf Vehicles for Towed Array Magnetometry

    DTIC Science & Technology

    2009-09-01

    Unfiltered 2006 Data Acquired with Chenowth Buggy at 15’ mag1 mag2 mag3 mag4 mag5 average bulk signature 2006 Unfiltered apg06_sn...Bidirectional Corrections for Filtered 2006 Data Acquired with Chenowth Buggy at 15’ mag1 mag2 mag3 mag4 mag5 average bulk signature 2006 Filtered...mag2 mag3 mag4 mag5 average bulk signature 2009 Aggressive Unfiltered apg09_15p_sn -22.8 -22.6 -24.3 -32.5 -28.0 -26.1

  1. Commercial-Off-The-Shelf Vehicles for Towed Array Magnetometry

    DTIC Science & Technology

    2009-09-01

    with Chenowth buggy at 15 ft. mag1 mag2 mag3 mag4 mag5 Average Bulk Signature 2006 Unfiltered apg06_sn 1.8 0.5 0.3 -2.3 -0.6 -0.1 apg06_ns...essentially zero. 38 Table 6. Bidirectional corrections for filtered 2006 data acquired with Chenowth buggy at 15 ft. mag1 mag2 mag3 mag4...2009 COTS vehicle data acquired at 15 ft with skidplate. mag1 mag2 mag3 mag4 mag5 Average Bulk Signature 2009 Aggressive Unfiltered

  2. Low-cost dipole hydrophone for use in towed arrays

    SciTech Connect

    Abraham, B.M.

    1996-04-01

    The design, fabrication, and testing of a low-cost acoustic particle velocity sensor are described. The primary design parameters for the dipole hydrophone are low-cost, low-mass, and small size. The sensor uses commercially available geophones to locally measure one or more components of the acoustic particle velocity field. The geophones are encapsulated in a syntactic foam to reduce their average density and hence increase their acoustic sensitivity. This method of fabrication greatly reduces costs compared to conventional methods which use machined cases. The on-axis voltage sensitivity was measured experimentally using two methods. The first used a uniaxial vibration shaker to estimate the intrinsic velocity sensitivity of the encapsulated geophone with the case fixed to the shaker head. The second measured the {ital in} {ital situ} acoustic sensitivity in water. Theoretical models of the voltage sensitivity for these two cases are developed and the results compare very well with the experimental data. Additionally, rotator tests were performed at frequencies of 100, 500, 600, and 1000 Hz to measure the quality of the dipole directivity pattern in water. Near-theoretical dipole patterns, with nulls better than 30 dB, were measured. {copyright} {ital 1996 American Institute of Physics.}

  3. Marine Towed Array Technology Demonstration Blossom Point Research Facility

    DTIC Science & Technology

    2009-08-01

    23 MTA Demonstration Report Blossom Point Research Facility iii 5-5 The line of fiberglass poles were established to locate the calibration...targets ............................... 24 5-6 The diver is preparing to install the target adjacent to the pole ...correctly, this instrument completely removes any measurable remnant signal from any steel item that can pass through its aperture. Figure 5-3. A

  4. Automatic magnetometer calibration with small space coverage

    NASA Astrophysics Data System (ADS)

    Wahdan, Ahmed

    The use of a standalone Global Navigation Satellite System (GNSS) has proved to be insufficient when navigating indoors or in urban canyons due to multipath or obstruction. Recent technological advances in low cost micro-electro-mechanical system (MEMS) -- based sensors (like accelerometers, gyroscopes and magnetometers) enabled the development of sensor-based navigation systems. Although MEMS sensors are low-cost, lightweight, small size, and have low-power consumption, they have complex error characteristics. Accurate computation of the heading angle (azimuth) is one of the most important aspects of any navigation system. It can be computed either by gyroscopes or magnetometers. Gyroscopes are inertial sensors that can provide the angular rate from which the heading can be calculated, however, their outputs drift with time. Moreover, the accumulated errors due to mathematical integration, performed to obtain the heading angle, lead to large heading errors. On the other hand, magnetometers do not suffer from drift and the calculation of heading does not suffer from error accumulation. They can provide an absolute heading from the magnetic north by sensing the earth's magnetic field. However, magnetometer readings are usually affected by magnetic fields, other than the earth magnetic field, and by other error sources; therefore magnetometer calibration is required to use magnetometer as a reliable source of heading in navigation applications. In this thesis, a framework for fast magnetometer calibration is proposed. This framework requires little space coverage with no user involvement in the calibration process, and does not need specific movements to be performed. The proposed techniques are capable of performing both 2-dimensional (2D) and 3-dimensional (3D) calibration for magnetometers. They are developed to consider different scenarios suitable for different applications, and can benefit from natural device movements. Some applications involve tethering the

  5. Spaced-based search coil magnetometers

    NASA Astrophysics Data System (ADS)

    Hospodarsky, George B.

    2016-12-01

    Search coil magnetometers are one of the primary tools used to study the magnetic component of low-frequency electromagnetic waves in space. Their relatively small size, mass, and power consumption, coupled with a good frequency range and sensitivity, make them ideal for spaceflight applications. The basic design of a search coil magnetometer consists of many thousands of turns of wire wound on a high permeability core. When a time-varying magnetic field passes through the coil, a time-varying voltage is induced due to Faraday's law of magnetic induction. The output of the coil is usually attached to a preamplifier, which amplifies the induced voltage and conditions the signal for transmission to the main electronics (usually a low-frequency radio receiver). Search coil magnetometers are usually used in conjunction with electric field antenna to measure electromagnetic plasma waves in the frequency range of a few hertz to a few tens of kilohertzs. Search coil magnetometers are used to determine the properties of waves, such as comparing the relative electric and magnetic field amplitudes of the waves, or to investigate wave propagation parameters, such as Poynting flux and wave normal vectors. On a spinning spacecraft, they are also sometimes used to determine the background magnetic field. This paper presents some of the basic design criteria of search coil magnetometers and discusses design characteristics of sensors flown on a number of spacecraft.

  6. Analytical balance-based Faraday magnetometer

    NASA Astrophysics Data System (ADS)

    Riminucci, Alberto; Uhlarz, Marc; De Santis, Roberto; Herrmannsdörfer, Thomas

    2017-03-01

    We introduce a Faraday magnetometer based on an analytical balance in which we were able to apply magnetic fields up to 0.14 T. We calibrated it with a 1 mm Ni sphere previously characterized in a superconducting quantum interference device (SQUID) magnetometer. The proposed magnetometer reached a theoretical sensitivity of 3 × 10-8 A m2. We demonstrated its operation on magnetic composite scaffolds made of poly(ɛ-caprolactone)/iron-doped hydroxyapatite. To confirm the validity of the method, we measured the same scaffold properties in a SQUID magnetometer. The agreement between the two measurements was within 5% at 0.127 T and 12% at 24 mT. With the addition, for a small cost, of a permanent magnet and computer controlled linear translators, we were thus able to assemble a Faraday magnetometer based on an analytical balance, which is a virtually ubiquitous instrument. This will make simple but effective magnetometry easily accessible to most laboratories, in particular, to life sciences ones, which are increasingly interested in magnetic materials.

  7. The Magnetometer Instrument on MESSENGER

    NASA Astrophysics Data System (ADS)

    Anderson, Brian J.; Acuña, Mario H.; Lohr, David A.; Scheifele, John; Raval, Asseem; Korth, Haje; Slavin, James A.

    2007-08-01

    The Magnetometer (MAG) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission is a low-noise, tri-axial, fluxgate instrument with its sensor mounted on a 3.6-m-long boom. The boom was deployed on March 8, 2005. The primary MAG science objectives are to determine the structure of Mercury’s intrinsic magnetic field and infer its origin. Mariner 10 observations indicate a planetary moment in the range 170 to 350 nT R {M/3} (where R M is Mercury’s mean radius). The uncertainties in the dipole moment are associated with the Mariner 10 trajectory and variability of the measured field. By orbiting Mercury, MESSENGER will significantly improve the determination of dipole and higher-order moments. The latter are essential to understanding the thermal history of the planet. MAG has a coarse range, ±51,300 nT full scale (1.6-nT resolution), for pre-flight testing, and a fine range, ±1,530 nT full scale (0.047-nT resolution), for Mercury operation. A magnetic cleanliness program was followed to minimize variable and static spacecraft-generated fields at the sensor. Observations during and after boom deployment indicate that the fixed residual field is less than a few nT at the location of the sensor, and initial observations indicate that the variable field is below 0.05 nT at least above about 3 Hz. Analog signals from the three axes are low-pass filtered (10-Hz cutoff) and sampled simultaneously by three 20-bit analog-to-digital converters every 50 ms. To accommodate variable telemetry rates, MAG provides 11 output rates from 0.01 s-1 to 20 s-1. Continuous measurement of fluctuations is provided with a digital 1-10 Hz bandpass filter. This fluctuation level is used to trigger high-time-resolution sampling in eight-minute segments to record events of interest when continuous high-rate sampling is not possible. The MAG instrument will provide accurate characterization of the intrinsic planetary field, magnetospheric structure, and

  8. Multi-flux-transformer MRI detection with an atomic magnetometer.

    PubMed

    Savukov, Igor; Karaulanov, Todor

    2014-10-18

    Recently, anatomical ultra-low field (ULF) MRI has been demonstrated with an atomic magnetometer (AM). A flux-transformer (FT) has been used for decoupling MRI fields and gradients to avoid their negative effects on AM performance. The field of view (FOV) was limited because of the need to compromise between the size of the FT input coil and MRI sensitivity per voxel. Multi-channel acquisition is a well-known solution to increase FOV without significantly reducing sensitivity. In this paper, we demonstrate twofold FOV increase with the use of three FT input coils. We also show that it is possible to use a single atomic magnetometer and single acquisition channel to acquire three independent MRI signals by applying a frequency-encoding gradient along the direction of the detection array span. The approach can be generalized to more channels and can be critical for imaging applications of non-cryogenic ULF MRI where FOV needs to be large, including head, hand, spine, and whole-body imaging.

  9. Multi-flux-transformer MRI detection with an atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Savukov, Igor; Karaulanov, Todor

    2014-12-01

    Recently, anatomical ultra-low field (ULF) MRI has been demonstrated with an atomic magnetometer (AM). A flux-transformer (FT) has been used for decoupling MRI fields and gradients to avoid their negative effects on AM performance. The field of view (FOV) was limited because of the need to compromise between the size of the FT input coil and MRI sensitivity per voxel. Multi-channel acquisition is a well-known solution to increase FOV without significantly reducing sensitivity. In this paper, we demonstrate twofold FOV increase with the use of three FT input coils. We also show that it is possible to use a single atomic magnetometer and single acquisition channel to acquire three independent MRI signals by applying a frequency-encoding gradient along the direction of the detection array span. The approach can be generalized to more channels and can be critical for imaging applications of non-cryogenic ULF MRI where FOV needs to be large, including head, hand, spine, and whole-body imaging.

  10. MAGDAS I and II Magnetometers in Peru

    NASA Astrophysics Data System (ADS)

    Choque, Ed.; Ishitsuka, J.; Yumoto, K.; Veliz, O.; Rosales, D.

    2014-01-01

    The Department of Terrestrial Magnetism of the Car negie Institution of Washington founded in 1919 the Huancayo Observatory, in Peru (Lat. -12.060, Long - 75.210) and installed a classical magnetometer which has provided a long standing flow of data since March 1st, 1922. Today, there are 10 magnetometers in operation in Peru. On October 13th, 2006, Space Environment Research Center - SERC of Kyushu University installed a new Magnetic Dat a Acquisition System MAGDAS I (PI; Prof. K. Yumoto) at Ancon Observatory (Geographic Latitude: -11.790, Longitude: - 77.160 and Geomagnetic Latitude (2000): 3.100 and Longitude (2000): 354.660). On July 13th, 2011, SERC installed a MAGDAS II at Ica Solar Station (Geographic Latitude: - 140 04' Longitude: -750 44'). Details of the magnetometer that we are hosting will be explained in this presentation.

  11. Investigations and Tests in the Towing Basin at Guidonia

    NASA Technical Reports Server (NTRS)

    Cremona, C

    1939-01-01

    The experimental methods at the Guidonia towing basin are discussed including specifications. Some of the components examined are the bridge towing carriage, side towing carriage, catapult installation, and dynamometer systems. Tests were performed on hulls and floats, as well as motor boats and torpedo shaped bodies. Theoretical investigations were also performed to determine pressure distributions on geometrically simple bodies, propagation of small wave motions, and planing and submerged surfaces.

  12. Carbon Fiber TOW Angle Determination Using Microwave Reflectometry

    NASA Technical Reports Server (NTRS)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    NASA's Advanced Composites Project is investigating technologies that increase automated remote inspection of aircraft composite structures. Therefore, microwave Frequency Domain Reflectometry (FDR) is being investigated as a method of enabling rapid remote inspection of angular orientation of the tow using microwave radiation. This work will present preliminary data demonstrating that frequency shifts in the reflection spectrum of a carbon fiber tow sample are indicative of the angle of the tow with respect to an interrogating antenna's linear polarized output.

  13. Computer-Aided Decision Making for Ocean Towing

    DTIC Science & Technology

    1989-05-12

    3 Resistance Prediction .............................................................................. 32 3.1 Tow Resistance...80,000 120,000 Wave Angle (deg) 0 60 120 180 Table 2.1. Data Base Towing Parameters. 31 Chapter 3 Resistance Prediction In order to use the extreme...this speed may be greater than or less than the desired tow speed. An exact solution is not computed because the accuracy of the resistance prediction methods

  14. Aircraft attitude measurement using a vector magnetometer

    NASA Technical Reports Server (NTRS)

    Peitila, R.; Dunn, W. R., Jr.

    1977-01-01

    The feasibility of a vector magnetometer system was investigated by developing a technique to determine attitude given magnetic field components. Sample calculations are then made using the earth's magnetic field data acquired during actual flight conditions. Results of these calculations are compared graphically with measured attitude data acquired simultaneously with the magnetic data. The role and possible implementation of various reference angles are discussed along with other pertinent considerations. Finally, it is concluded that the earth's magnetic field as measured by modern vector magnetometers can play a significant role in attitude control systems.

  15. Towed Twin-Fuselage Glider Launch System (CGI Animation Version 2)

    NASA Video Gallery

    The towed glider is an element of the novel rocket-launching concept of the Towed Glider Air-Launch System (TGALS). The TGALS demonstration’s goal is to provide proof-of-concept of a towed, airborn...

  16. Diffusive suppression of AC-Stark shifts in atomic magnetometers

    PubMed Central

    Sulai, I. A.; Wyllie, R.; Kauer, M.; Smetana, G. S.; Wakai, R. T.; Walker, T. G.

    2016-01-01

    In atomic magnetometers, the vector AC-Stark shift associated with circularly polarized light generates spatially varying effective magnetic fields, which limit the magnetometer response and serve as sources of noise. We describe a scheme whereby optically pumping a small subvolume of the magnetometer cell and relying on diffusion to transport polarized atoms allows a magnetometer to be operated with minimal sensitivity to the AC-Stark field. © 2013 Optical Society of America PMID:23503278

  17. Method of performing MRI with an atomic magnetometer

    DOEpatents

    Savukov, Igor Mykhaylovich; Matlashov, Andrei Nikolaevich; Espy, Michelle A; Volegov, Petr Lvovich; Kraus, Jr., Robert Henry; Zotev, Vadim Sergeyevich

    2013-08-27

    A method and apparatus are provided for performing an in-situ magnetic resonance imaging of an object. The method includes the steps of providing an atomic magnetometer, coupling a magnetic field generated by magnetically resonating samples of the object through a flux transformer to the atomic magnetometer and measuring a magnetic resonance of the atomic magnetometer.

  18. Method of performing MRI with an atomic magnetometer

    DOEpatents

    Savukov, Igor Mykhaylovich; Matlashov, Andrei Nikolaevich; Espy, Michelle A.; Volegov, Petr Lvovich; Kraus, Jr., Robert Henry; Zotev, Vadim Sergeyevich

    2012-11-06

    A method and apparatus are provided for performing an in-situ magnetic resonance imaging of an object. The method includes the steps of providing an atomic magnetometer, coupling a magnetic field generated by magnetically resonating samples of the object through a flux transformer to the atomic magnetometer and measuring a magnetic resonance of the atomic magnetometer.

  19. Flux-gate magnetometer for Mars exploration

    NASA Astrophysics Data System (ADS)

    Zhao, Hua; Zhu, G. W.; Yu, P.; Wang, J. D.; Yu, M. F.; Li, L.; Sun, Y. Q.; Chen, S. W.; Liao, H. Z.; Zhou, B.; Feng, Y. Y.

    2008-10-01

    A micro-satellite, Yinghuo-1, would be launched with Russian spacecraft, Phobos-Grunt in October, 2009 to investigate the space environment around Mars. YH-1 and Phobos-Grunt forms a two-point measurement configuration in the Martian space environment. YH-1 and Phobos-Grunt are equipped with similar magnetic field and plasma detecting payload on two spacecraft would give some coordinated exploration around Mars. YH-1 would orbit Mars with periapsis of 800 km above the Martian surface, and apoapsis about 80000km to the center of Mars. The orbit inclination is in the range of 0~7° to the Martian equator. A flux-gate type magnetometer, with two tri-axial sensors, is developed for YH-1 spacecraft. Two sensors are mounted on one-side of the deployable solar panel with a radial separation about 45cm to function as a gradiometer to minimize the affects of platform remanence. The dynamic range of the magnetometer is +/-256nT with a 16-bit ADC converter, and the noise level is better than 0.01nT/√Hz, to measure three-component magnetic field from DC to 10Hz. Flux-gate magnetometer would work together with the Plasma Package onboard of YH-1 to investigate the Martian bow shock, magnetosheath, magnetic pileup region (MPR). A detail description of the flux-gate magnetometer is presented in this paper, with test and calibration results.

  20. Anatomical MRI with an atomic magnetometer.

    PubMed

    Savukov, I; Karaulanov, T

    2013-06-01

    Ultra-low field (ULF) MRI is a promising method for inexpensive medical imaging with various additional advantages over conventional instruments such as low weight, low power, portability, absence of artifacts from metals, and high contrast. Anatomical ULF MRI has been successfully implemented with SQUIDs, but SQUIDs have the drawback of a cryogen requirement. Atomic magnetometers have sensitivity comparable to SQUIDs and can be in principle used for ULF MRI to replace SQUIDs. Unfortunately some problems exist due to the sensitivity of atomic magnetometers to a magnetic field and gradients. At low frequency, noise is also substantial and a shielded room is needed for improving sensitivity. In this paper, we show that at 85 kHz, the atomic magnetometer can be used to obtain anatomical images. This is the first demonstration of any use of atomic magnetometers for anatomical MRI. The demonstrated resolution is 1.1 mm×1.4 mm in about 6 min of acquisition with SNR of 10. Some applications of the method are discussed. We discuss several measures to increase the sensitivity to reach a resolution 1 mm×1 mm.

  1. The DE magnetometer preprocessor users guide

    NASA Technical Reports Server (NTRS)

    Salter, L. M.; Byrnes, J. B.

    1982-01-01

    A users guide for the Dynamics Explorer magnetometer preprocessor computer program is provided. This program is written in Xerox Extended FORTRAN IV and is used to process telemetry data in order to provide data files for use in analysis programs. This preprocessor is designed to operate on the Sigma 9 and the IBM 4341.

  2. Aerodynamics modeling of towed-cable dynamics

    SciTech Connect

    Kang, S.W.; Latorre, V.R.

    1991-01-17

    The dynamics of a cable/drogue system being towed by an orbiting aircraft has been investigated as a part of an LTWA project for the Naval Air Systems Command. We present here a status report on the tasks performed under Phase 1. We have accomplished the following tasks under Phase 1: A literature survey on the towed-cable motion problem has been conducted. While both static (steady-state) and dynamic (transient) analyses exist in the literature, no single, comprehensive analysis exists that directly addresses the present problem. However, the survey also reveals that, when judiciously applied, these past analyses can serve as useful building blocks for approaching the present problem. A numerical model that addresses several aspects of the towed-cable dynamic problem has been adapted from a Canadian underwater code for the present aerodynamic situation. This modified code, called TOWDYN, analyzes the effects of gravity, tension, aerodynamic drag, and wind. Preliminary results from this code demonstrate that the wind effects alone CAN generate the drogue oscillation behavior, i.e., the yo-yo'' phenomenon. This code also will serve as a benchmark code for checking the accuracy of a more general and complete R D'' model code. We have initiated efforts to develop a general R D model supercomputer code that also takes into account other physical factors, such as induced oscillations and bending stiffness. This general code will be able to evaluate the relative impacts of the various physical parameters, which may become important under certain conditions. This R D code will also enable development of a simpler operational code that can be used by the Naval Air personnel in the field.

  3. 77 FR 12863 - Towing Safety Advisory Committee; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-02

    ... meeting of the Towing Vessel Inspection Work Group. The committee will reconvene on March 21, 2012. The meeting of the TSAC on both days and the meeting of the working group are open to the public. DATES: March... meeting of the Towing Vessel Inspection Work Group. March 21, 2012, the TSAC will reconvene 8:30 a.m. to...

  4. 33 CFR 83.24 - Towing and pushing (Rule 24).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... line above the sternlight; and (5) When the length of the tow exceeds 200 meters, a diamond shape where... exceeds 200 meters, a diamond shape where it can best be seen. (f) Vessels being towed alongside or pushed... alongside each other shall be lighted as one vessel or object; (4) A diamond shape at or near the...

  5. 33 CFR 83.24 - Towing and pushing (Rule 24).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... line above the sternlight; and (5) When the length of the tow exceeds 200 meters, a diamond shape where... exceeds 200 meters, a diamond shape where it can best be seen. (f) Vessels being towed alongside or pushed... alongside each other shall be lighted as one vessel or object; (4) A diamond shape at or near the...

  6. 33 CFR 83.24 - Towing and pushing (Rule 24).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... line above the sternlight; and (5) When the length of the tow exceeds 200 meters, a diamond shape where... exceeds 200 meters, a diamond shape where it can best be seen. (f) Vessels being towed alongside or pushed... alongside each other shall be lighted as one vessel or object; (4) A diamond shape at or near the...

  7. 33 CFR 83.24 - Towing and pushing (Rule 24).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... line above the sternlight; and (5) When the length of the tow exceeds 200 meters, a diamond shape where... exceeds 200 meters, a diamond shape where it can best be seen. (f) Vessels being towed alongside or pushed... alongside each other shall be lighted as one vessel or object; (4) A diamond shape at or near the...

  8. 15. VIEW NORTHNORTHEAST OF TOW TANK No. 2, DEWATERED. ENCLOSED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. VIEW NORTH-NORTHEAST OF TOW TANK No. 2, DEWATERED. ENCLOSED AREAS AT BACK OF TUNNEL IS A HOUSING FOR CONDUCTING PERFORMANCE TESTING ON AIRCRAFT MODELS IN A VORTEX. - NASA Langley Research Center, Seaplane Towing Channel, 108 Andrews Street, Hampton, Hampton, VA

  9. Atropine Effects on the Operation of the Tow Missile Launcher.

    DTIC Science & Technology

    1987-03-01

    Missile Guidance Unit ( MGU ). The MGU operates in conjunction with the TOW sight to provide both azimuth (X) and elevation (Y) error signals. The operation...and Y error signals are then processed by the TOW’s MGU , digitized within the Apple by a 12-bit hybrid analog-to-digital converter and recorded on disk

  10. A plateau in the sensitivity of a compact optically pumped atomic magnetometer

    SciTech Connect

    Mizutani, Natsuhiko Okano, Kazuhisa; Ban, Kazuhiro; Ichihara, Sunao; Terao, Akira; Kobayashi, Tetsuo

    2014-05-15

    In a compact optically pumped atomic magnetometer (OPAM), there is a plateau in the sensitivity where the dependence of the sensitivity on pumping power is small compared with that predicted by the uniform polarization model. The mechanism that generates this plateau was explained by numerical analysis. The distribution of spin polarization in the alkali metal cell of an OPAM was modeled using the Bloch equation incorporating a diffusion term and an equation for the attenuation of the pump beam. The model was well-fitted to the experimental results for a module with a cubic cell with 20 mm sides and pump and probe beams with 8 mm diameter. On the plateau, strong magnetic response was generated at the regions that were not illuminated directly by the intense pump beam, while at the same time spin polarization as large as 0.5 was maintained due to diffusion of the spin-polarized atoms. Thus, the sensitivity of the magnetometer monitored with a probe beam decreases only slightly with increasing pump beam intensity because the spin polarization under an intense pump beam is saturated. This plateau, which is characteristic of this type of magnetometer using a narrow pump and probe beams, can be used in arrays of magnetometers because it enables stable operation with little sensitivity fluctuation from changes in pump beam power.

  11. Quantum magnetometers as a base for atomic clock

    NASA Astrophysics Data System (ADS)

    Sagitov, E. A.; Ermak, S. V.; Petrenko, M. V.; Semenov, V. V.

    2016-11-01

    The possibility of the atomic clock based on two quantum magnetometer system development is demonstrated. One of the magnetometers is self-oscillation type, another is Mz- type magnetometer based on end-state UHF resonance. The laser pumping of 87Rb atoms placed into antirelaxation coated sell is provided. The magnetometers frequency difference fluctuations experimental results are represented and Allan deviation is determined. The role of the radio-optical resonance frequency light shift different components is denoted for the determination of the quantum magnetometers optimal operation mode. The effect of the light shift compensation is demonstrated.

  12. Engineered Polymer Composites Through Electrospun Nanofiber Coating of Fiber Tows

    NASA Technical Reports Server (NTRS)

    Kohlman, Lee W.

    2013-01-01

    Toughening and other property enhancements of composite materials are typically implemented by-modifying the bulk properties of the constituents, either the fiber or matrix materials. This often leads to difficulties in processing and higher material costs. Many composites consist of tows or yarns (thousands of individual fibers) that are either filament wound or processed into a fabric by weaving or braiding. The matrix material can be added to the tow or fabric before final processing, resulting in a prepreg material, or infused into the fiber material during final processing by a variety of methods. By using a direct electrospun deposition method to apply thermoplastic nanofiber to the surface of the tows, the tow-tow interface in the resulting composite can be modified while using otherwise conventional materials and handling processes. Other materials of interest could also be incorporated into the electrospun precursor.

  13. ADCP measurements from a towed fish

    NASA Astrophysics Data System (ADS)

    Kaneko, Arata; Koterayama, Wataru

    The acoustic Doppler current profiler (ADCP) is a powerful instrument that can measure detailed vertical profiles of ocean currents. ADCPs are often permanently mounted on research vessels and used to survey ocean currents rapidly over large areas of the ocean. We recently began development of a towed "fish" (instrument package) that would contain an ADCP with the same capabilities as a vessel-mounted ADCP but that would allow us greater flexibility and improved data. Here we describe our initial efforts, present some of our first results, and summarize our near-term plans for improving our present ADCP fish system. We are developing the ability to make ADCP measurements from a towed fish rather than from a ship because we want to be able to measure ocean currents accurately even under severe sea surface conditions,reduce the influence of cavitation noise generated by the ship's propeller,eliminate interference caused by bubbles entrained under the ship's hull, anduse the instrument on unspecified research ships.

  14. Magnetometer Searches for Ultra Low Mass Fields

    NASA Astrophysics Data System (ADS)

    Romalis, Michael

    2017-01-01

    New spin interactions arise in a variety of extensions to the Standard Model. Well-known spin-dependent effects, such as permanent electric dipole moments and violations of Lorentz and CPT symmetries, have been searched for in many experiments. The existence of low-mass axion-like particles would also generate spin-dependent effects that can be searched for in similar experiments, but often with unique signatures. Since particles with spin also have a magnetic moment, such experiments are automatically sensitive to ordinary magnetic fields and one of the challenges is to eliminate such effects, using for example, two different spin species in a co-magnetometer arrangement. I will describe several past and on-going experiments using co-magnetometers based on nuclear spin-polarized noble gases. These experiments are used to search for both axion-like dark matter and for axion-mediated forces that are independent of dark matter.

  15. All-optical vector atomic magnetometer.

    PubMed

    Patton, B; Zhivun, E; Hovde, D C; Budker, D

    2014-07-04

    We demonstrate an all-optical magnetometer capable of measuring the magnitude and direction of a magnetic field using nonlinear magneto-optical rotation in cesium vapor. Vector capability is added by effective modulation of the field along orthogonal axes and subsequent demodulation of the magnetic-resonance frequency. This modulation is provided by the ac Stark shift induced by circularly polarized laser beams. The sensor exhibits a demonstrated rms noise floor of ∼65  fT/√[Hz] in measurement of the field magnitude and 0.5  mrad/√[Hz] in the field direction; elimination of technical noise would improve these sensitivities to 12  fT/√[Hz] and 10  μrad/√[Hz], respectively. Applications for this all-optical vector magnetometer would include magnetically sensitive fundamental physics experiments, such as the search for a permanent electric dipole moment of the neutron.

  16. MAGSAT: Vector magnetometer absolute sensor alignment determination

    NASA Technical Reports Server (NTRS)

    Acuna, M. H.

    1981-01-01

    A procedure is described for accurately determining the absolute alignment of the magnetic axes of a triaxial magnetometer sensor with respect to an external, fixed, reference coordinate system. The method does not require that the magnetic field vector orientation, as generated by a triaxial calibration coil system, be known to better than a few degrees from its true position, and minimizes the number of positions through which a sensor assembly must be rotated to obtain a solution. Computer simulations show that accuracies of better than 0.4 seconds of arc can be achieved under typical test conditions associated with existing magnetic test facilities. The basic approach is similar in nature to that presented by McPherron and Snare (1978) except that only three sensor positions are required and the system of equations to be solved is considerably simplified. Applications of the method to the case of the MAGSAT Vector Magnetometer are presented and the problems encountered discussed.

  17. Tether Magnetometer system for study of Mercury Magnetophysics

    NASA Astrophysics Data System (ADS)

    Colombatti, G.; Angrilli, F.; Bianchini, G.; Crepaldi, A.

    2001-11-01

    BepiColombo mission will explore Mercury and its environment; the scientific payload will be onboard two orbiters and a lander: a planetary orbiter for spectrometric analyses, a magnetospheric orbiter for the observation of the magnetic field and its interactions with the solar wind and a lander for the in-situ study of surface and subsurface properties. The environment in which the mission will operate is extremely hard due to the position and the proximity to the sun (i.e. tidal forces); payloads will be subject to high temperatures variations and harsh day-night excursions; severe radiation bombardment will damage instruments if not enough shielded. Mariner 10 observations began to outline the particular characteristics of Mercury's weak magnetic field and active magnetosphere, absence of ionosphere and atmosphere. Nevertheless the non-exhaustive data-sets has leaded to ambiguities which can be resolved only by the acquisition of new remote measurements. Objective/goal of the proposed Tethered Magnetometer System (TEMS) are measurements in low orbit (in particular MPOs orbit) of the intrinsic weak magnetic field and hydromagnetic and thermoelectric phenomena not measurable by MMO instruments. For the development of the instrument no increase in the weight and in the thermal shielding of the MPO are required. Such a system will be host on CPM (chimic propulsion module) and will have a minimal impact configuration thanks to the low mass and the low volume of the deployable subsatellite housing the magnetometer. The CPM, after the release of the Lander module, has finished his operating life and won't be used any more. Moreover, once deployed the apoapsis of the tether system will be less than 400 km, with no possibility to harm the orbiter. After all mission operations with CPM are finished a reel system deploys a 500m tether with subsatellite at the end housing the magnetometer far away from magnetic noise of the CPM; power will be used directly from the one of

  18. Low Cost, Low Power, High Sensitivity Magnetometer

    DTIC Science & Technology

    2008-12-01

    Guedes , A.; et al., 2008: Hybrid - LOW COST, LOW POWER, HIGH SENSITIVITY MAGNETOMETER A.S. Edelstein*, James E. Burnette, Greg A. Fischer, M.G...Edelstein, 2004; Burnette, 2008), we suggested a method for mitigating the problem of 1/f noise. We and others ( Guedes , 2008) have been utilizing...6. Guedes , A.; et al., 2008: Hybrid - 3magnetoresistive/microelectromechanical devices for static field modulation and sensor 1/f noise

  19. Integration of micro-fabricated atomic magnetometers on military systems

    NASA Astrophysics Data System (ADS)

    Schultz, Gregory; Mhaskar, Rahul; Prouty, Mark; Miller, Jonathan

    2016-05-01

    A new generation of ultra-high sensitivity magnetic sensors based on innovative micro-electromechanical systems (MEMS) are being developed and incorporated into military systems. Specifically, we are currently working to fully integrate the latest generation of MicroFabricated Atomic Magnetometers (MFAMs) developed by Geometrics on defense mobility systems such as unmanned systems, military vehicles and handheld units. Recent reductions in size, weight, and power of these sensors has enabled new deployment opportunities for improved sensitivity to targets of interest, but has also introduced new challenges associated with noise mitigation, mission configuration planning, and data processing. Our work is focused on overcoming the practical aspects of integrating these sensors with various military platforms. Implications associated with utilizing these combined sensor systems in working environments are addressed in order to optimize signal-to-noise ratios, detection probabilities, and false alarm mitigation. Specifically, we present collaborative work that bridges the gap between commercial specialists and operation platform integration organizations including magnetic signature characterization and mitigation as well as the development of simulation tools that consider a wide array of sensor, environmental, platform, and mission-level parameters. We discuss unique deployment concepts for explosive hazard target geolocation, and data processing. Applications include configurations for undersea and underground threat detection - particularly those associated with stationary or mobile explosives and compact metallic targets such as munitions, subsea threats, and other hazardous objects. We show the potential of current and future features of miniaturized magnetic sensors including very high magnetic field sensitivities, bandwidth selectivity, and array processing.

  20. Aeroelastic Tailoring via Tow Steered Composites

    NASA Technical Reports Server (NTRS)

    Stanford, Bret K.; Jutte, Christine V.

    2014-01-01

    The use of tow steered composites, where fibers follow prescribed curvilinear paths within a laminate, can improve upon existing capabilities related to aeroelastic tailoring of wing structures, though this tailoring method has received relatively little attention in the literature. This paper demonstrates the technique for both a simple cantilevered plate in low-speed flow, as well as the wing box of a full-scale high aspect ratio transport configuration. Static aeroelastic stresses and dynamic flutter boundaries are obtained for both cases. The impact of various tailoring choices upon the aeroelastic performance is quantified: curvilinear fiber steering versus straight fiber steering, certifiable versus noncertifiable stacking sequences, a single uniform laminate per wing skin versus multiple laminates, and identical upper and lower wing skins structures versus individual tailoring.

  1. TOW Missile Pallet MIL-STD-1660 Tests

    DTIC Science & Technology

    1993-08-01

    0 DTICS ELECTE FEB 2 19941 FINAL REPORT C U ow AUGUST 1993 (V V Lfl3 NNE REPORT NO. 93-23 TOW MISSILE PALLET MIL- STD -1660 TESTS Prepared for...TITLE gOnakde Secwir Casaftedon) TOW Missile Pallet MIL- STD -1660 Tests 12. PERSONAL AUTHOR(S) Jason B. Solberg 13s. TYPE OF REPORT 13b. TIME COVERED...and Engineering Center (ARDEC) to test the TOW missile pallet. This report contains the procedures, results, and recommendations from the MIL- STD

  2. Thermal Testing of Tow-Placed, Variable Stiffness Panels

    NASA Technical Reports Server (NTRS)

    Wu, K. Chauncey; Guerdal, Zafer

    2001-01-01

    Commercial systems for precise placement of pre-preg composite tows are enabling technology that allows fabrication of advanced composite structures in which the tows may be precisely laid down along curvilinear paths within a given ply. For laminates with curvilinear tow paths, the fiber orientation angle varies continuously throughout the laminate, and is not required to be straight and parallel in each ply as in conventional composite laminates. Hence, the stiffness properties vary as a function of location in the laminate, and the associated composite structure is called a "variable stiffness" composite structure.

  3. The MAGSAT vector magnetometer: A precision fluxgate magnetometer for the measurement of the geomagnetic field

    NASA Technical Reports Server (NTRS)

    Acuna, M. H.; Scearce, C. S.; Seek, J.; Scheifele, J.

    1978-01-01

    A description of the precision triaxial fluxgate magnetometer to be flown aboard the MAGSAT spacecraft is presented. The instrument covers the range of + or - 64,000 nT with a resolution of + or - 0.5 nT, an intrinsic accuracy of + or - 0.001% of full scale and an angular alignment stability of the order of 2 seconds of arc. It was developed at NASA's Goddard Space Flight Center and represents the state-of-the-art in precision vector magnetometers developed for spaceflight use.

  4. The atomic magnetometer: A new era in biomagnetism

    SciTech Connect

    Wakai, Ronald T.

    2014-11-07

    The high cost and impracticality of SQUID (Superconducting QUantum Interference Device) magnetometers has limited the expansion of magnetoencephalography (MEG) and magnetocardiography (MCG), especially in countries where the cost of liquid helium is high. A recent breakthrough, however, has the potential to radically change this situation. In 2003, a group at Princeton University demonstrated an atomic magnetometer, known as the SERF (spin-exchange free relaxation) magnetometer, with unprecedented sensitivity. Since then, several research groups have utilized SERF magnetometers to record MEG, MCG, and fetal MCG signals. Despite some modest drawbacks, it now seems almost certain that SERF magnetometers can replace SQUIDs for many applications. With a price tag that is likely to be far less than that of SQUIDs, SERF magnetometers can propel the next wave of growth in biomagnetism.

  5. The atomic magnetometer: A new era in biomagnetism

    NASA Astrophysics Data System (ADS)

    Wakai, Ronald T.

    2014-11-01

    The high cost and impracticality of SQUID (Superconducting QUantum Interference Device) magnetometers has limited the expansion of magnetoencephalography (MEG) and magnetocardiography (MCG), especially in countries where the cost of liquid helium is high. A recent breakthrough, however, has the potential to radically change this situation. In 2003, a group at Princeton University demonstrated an atomic magnetometer, known as the SERF (spin-exchange free relaxation) magnetometer, with unprecedented sensitivity. Since then, several research groups have utilized SERF magnetometers to record MEG, MCG, and fetal MCG signals. Despite some modest drawbacks, it now seems almost certain that SERF magnetometers can replace SQUIDs for many applications. With a price tag that is likely to be far less than that of SQUIDs, SERF magnetometers can propel the next wave of growth in biomagnetism.

  6. Optimization of buffer gas pressure for Rb atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Chen, Chang; Liu, Xiaohu; Qu, Tianliang; Yang, Kaiyong

    2015-08-01

    The optimization of buffer gas pressure is very important to improve the performance of the rubidium (Rb) atomic magnetometer. In this paper we briefly introduce the basic principle and the experimental method of the rubidium magnetometer based on Faraday rotation effect, and describe the factors affecting the magnetometer sensitivity, then analyze and summarize the mechanism of the influence of spin-exchange, spin-destruction collisions, radiation trapping and the spin diffusion on spin relaxation of Rb atoms. Based on this, the relationship between the rubidium magnetometer sensitivity, the spin relaxation rate and the gas chamber conditions (buffer gas pressure, the bubble radius, measuring temperature) is established. Doing calculations by the simulation software, how the magnetometer sensitivity and the relaxation rate vary with the gas chamber conditions can be seen; finally, the optimal values of the buffer gas pressure under certain gas chamber conditions are obtained. The work is significant for the engineering development of rubidium magnetometer.

  7. International solar polar mission: The vector helium magnetometer

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The functional requirements for the vector helium magnetometer (VHM) on the Solar Polar spacecraft are presented. The VHM is one of the two magnetometers on board that will measure the vector magnetic field along the Earth to Jupiter transfer trajectory, as well as in the vicinity of Jupiter and along the solar polar orbit following the Jupiter encounter. The interconnection between these two magnetometers and their shared data processing unit is illustrated.

  8. Laser magnetometer measurement of the natural remanent magnetization of rocks

    SciTech Connect

    Cotteverte, J.; Poirson, J.; Le Floch, A.; Bretenaker, F.; Chauvin, A.

    1997-06-01

    The ability of a laser magnetometer to measure the natural remanent magnetization of rocks is experimentally investigated. It is shown that the performance of such a magnetometer permits the rapid measurement of rock magnetizations of less than 1Am{sup {minus}1} in a laboratory without the need of any magnetic shielding or cryogenic facilities. Moreover, the laser magnetometer is experimentally shown to be able to measure the distribution of magnetization in spatially inhomogeneous samples. {copyright} {ital 1997 American Institute of Physics.}

  9. X-34 on lakebed prior to tow tests

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Following initial captive flight tests last year at NASA's Dryden Flight Research Center, Edwards Air Force Base, California, the X-34 technology demonstrator began a new series of tests last week in which it is being towed behind a semi-truck and released to coast on the Edwards dry lakebed. On July 20, 2000, it was towed and released twice at speeds of five and 10 miles per hour. On July 24, 2000, it was towed and released twice at 10 and 30 miles per hour. Twelve tests are planned during which the X-34 will be towed for distances up to 10,000 feet and released at speeds up to 80 miles per hour. The test series is expected to last at least six weeks.

  10. Composites from powder coated towpreg - Studies with variable tow sizes

    NASA Astrophysics Data System (ADS)

    Hugh, Maylene K.; Marchello, Joseph M.; Baucom, Robert M.; Johnston, Norman J.

    Part fabrication from composite materials usually costs less when larger fiber tow bundles are used. On the other hand, mechanical properties generally are lower for composites made using larger size tows. This situation gives rise to a choice between costs and properties in determining the best fiber tow bundle size to employ in preparing prepreg materials for part fabrication. To address this issue, unidirectional and eight harness satin fabric composite specimens were fabricated from 3k, 6k, and 12k carbon fiber reinforced LARC-TPI powder coated towpreg. Short beam shear strengths and longitudinal and transverse flexure properties were obtained for the unidirectional specimens. Tension properties were obtained for the eight harness satin woven towpreg specimens. Knowledge of the variation of properties with tow size may serve as a guide in material selection for part fabrication.

  11. Composites from powder coated towpreg - Studies with variable tow sizes

    NASA Technical Reports Server (NTRS)

    Hugh, Maylene K.; Marchello, Joseph M.; Baucom, Robert M.; Johnston, Norman J.

    1992-01-01

    Part fabrication from composite materials usually costs less when larger fiber tow bundles are used. On the other hand, mechanical properties generally are lower for composites made using larger size tows. This situation gives rise to a choice between costs and properties in determining the best fiber tow bundle size to employ in preparing prepreg materials for part fabrication. To address this issue, unidirectional and eight harness satin fabric composite specimens were fabricated from 3k, 6k, and 12k carbon fiber reinforced LARC-TPI powder coated towpreg. Short beam shear strengths and longitudinal and transverse flexure properties were obtained for the unidirectional specimens. Tension properties were obtained for the eight harness satin woven towpreg specimens. Knowledge of the variation of properties with tow size may serve as a guide in material selection for part fabrication.

  12. NASA Dryden Towed Glider Air-Launch Concept

    NASA Video Gallery

    NASA Dryden Flight Research Center is developing a novel space access, rocket launching technique called the Towed Glider Air-Launch Concept. The idea is to build a relatively inexpensive, remotely...

  13. 78 FR 14314 - Towing Safety Advisory Committee; Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-05

    ... and Recommendations for the Revision of NVIC 1-95, Voluntary Training Standards for Entry-Level..., Voluntary Training Standards for Entry-Level Personnel on Towing Industry Vessels. A final report will...

  14. A Compact, High Performance Atomic Magnetometer for Biomedical Applications

    PubMed Central

    Shah, Vishal K.; Wakai, Ronald T.

    2013-01-01

    We present a highly sensitive room-temperature atomic magnetometer (AM), designed for use in biomedical applications. The magnetometer sensor head is only 2×2×5 cm3 and is constructed using readily available, low-cost optical components. The magnetic field resolution of the AM is <10 fT/√Hz, which is comparable to cryogenically cooled superconducting quantum interference device (SQUID) magnetometers. We present side-by-side comparisons between our AM and a SQUID magnetometer, and show that equally high quality magnetoencephalography (MEG) and magnetocardiography (MCG) recordings can be obtained using our AM. PMID:24200837

  15. Autonomous navigation system based on GPS and magnetometer data

    NASA Technical Reports Server (NTRS)

    Julie, Thienel K. (Inventor); Richard, Harman R. (Inventor); Bar-Itzhack, Itzhack Y. (Inventor)

    2004-01-01

    This invention is drawn to an autonomous navigation system using Global Positioning System (GPS) and magnetometers for low Earth orbit satellites. As a magnetometer is reliable and always provides information on spacecraft attitude, rate, and orbit, the magnetometer-GPS configuration solves GPS initialization problem, decreasing the convergence time for navigation estimate and improving the overall accuracy. Eventually the magnetometer-GPS configuration enables the system to avoid costly and inherently less reliable gyro for rate estimation. Being autonomous, this invention would provide for black-box spacecraft navigation, producing attitude, orbit, and rate estimates without any ground input with high accuracy and reliability.

  16. A compact, high performance atomic magnetometer for biomedical applications.

    PubMed

    Shah, Vishal K; Wakai, Ronald T

    2013-11-21

    We present a highly sensitive room-temperature atomic magnetometer (AM), designed for use in biomedical applications. The magnetometer sensor head is only 2 × 2 × 5 cm3 and is constructed using readily available, low-cost optical components. The magnetic field resolution of the AM is <10 fT Hz–1/2, which is comparable to cryogenically cooled superconducting quantum interference device (SQUID) magnetometers. We present side-by-side comparisons between our AM and a SQUID magnetometer, and show that equally high quality magnetoencephalography and magnetocardiography recordings can be obtained using our AM.

  17. Method for Coating a Tow with an Electrospun Nanofiber

    NASA Technical Reports Server (NTRS)

    Kohlman, Lee W. (Inventor); Roberts, Gary D. (Inventor)

    2015-01-01

    Method and apparatus for enhancing the durability as well as the strength and stiffness of prepreg fiber tows of the sort used in composite materials are disclosed. The method involves adhering electrospun fibers onto the surface of such composite materials as filament-wound composite objects and the surface of prepreg fiber tows of the sort that are subsequently used in the production of composite materials of the filament-wound, woven, and braided sorts. The apparatus performs the methods described herein.

  18. An Acoustic Source Reactive to Tow Cable Strum

    DTIC Science & Technology

    2012-09-21

    shown in FIG. 3 in which the device is clamped to a tow cable 100 and which resembles a head mass of a Tonpilz transducer . The device 10 can be made of...steel or any other material appropriate for a transducer head mass. [0020] A Tonpilz transducer typically comprises a stack of piezoelectric...piezoelectric stack of a Tonpilz transducer that generates vibrational energy is replaced by the mile long tow cable 100 that generates vibrational

  19. Broadband Field Directionally Mapping using Maneuverable Acoustic Sensor Arrays

    DTIC Science & Technology

    2015-09-30

    Maneuverable Acoustic Sensor Arrays David Smith Dept. of Electrical and Computer Engineering Duke University, Box 90291 Durham, NC 27708 phone: (919) 660... acoustic arrays to resolve targets from interferers, and 2) improve the target detection, localization, and tracking performance of long arrays during tow...splines) EM algorithm. Both algorithms were run using a simulated 30 element acoustic vector sensor array with 900 snapshots. Attention has also

  20. Magnetic-field-compensation optical vector magnetometer.

    PubMed

    Papoyan, Aram; Shmavonyan, Svetlana; Khanbekyan, Alen; Khanbekyan, Karen; Marinelli, Carmela; Mariotti, Emilio

    2016-02-01

    A concept for an optical magnetometer used for the measurement of magnitude and direction of a magnetic field (B-field) in two orthogonal directions is developed based on double scanning of a B-field to compensate the measured field to zero value, which is monitored by a resonant magneto-optical process in an unshielded atomic vapor cell. Implementation of the technique using the nonlinear Hanle effect on the D2 line of rubidium demonstrates viability and efficiency of the proposed concept. The ways to enhance characteristics of the suggested technique and optimize its performance, as well as the possible extension to three-axis magnetometry, are discussed.

  1. NV Diamond Micro-Magnetometer Baseline Studies

    DTIC Science & Technology

    2009-08-12

    documentation. 14. ABSTRACT The goal of this program was to identify applications for which the unique properties of the nitrogen-vacancy (NY) diamond...program was to identify applications for which the unique properties of the nitrogen-vacancy (NV) diamond magnetometer gives a significant advantage...imaging applications such as single neuron imaging were also explored. Table of contents: Statement of the problem………………………………………..………………… 1 Single NV

  2. Magnetometer Based on Optoelectronic Microwave Oscillator

    NASA Technical Reports Server (NTRS)

    Maleki, Lute; Strekalov, Dmitry; Matsko, Andrey

    2005-01-01

    proposed instrument, intended mainly for use as a magnetometer, would include an optoelectronic oscillator (OEO) stabilized by an atomic cell that could play the role of a magnetically tunable microwave filter. The microwave frequency would vary with the magnetic field in the cell, thereby providing an indication of the magnetic field. The proposed magnetometer would offer a combination of high accuracy and high sensitivity, characterized by flux densities of less than a picotesla. In comparison with prior magnetometers, the proposed magnetometer could, in principle, be constructed as a compact, lightweight instrument: It could fit into a package of about 10 by 10 by 10 cm and would have a mass <0.5 kg. As described in several prior NASA Tech Briefs articles, an OEO is a hybrid of photonic and electronic components that generates highly spectrally pure microwave radiation, and optical radiation modulated by the microwave radiation, through direct conversion between laser light and microwave radiation in an optoelectronic feedback loop. As used here, "atomic cell" signifies a cell containing a vapor, the constituent atoms of which can be made to undergo transitions between quantum states, denoted hyperfine levels, when excited by light in a suitable wavelength range. The laser light must be in this range. The energy difference between the hyperfine levels defines the microwave frequency. In the proposed instrument (see figure), light from a laser would be introduced into an electro-optical modulator (EOM). Amplitude-modulated light from the exit port of the EOM would pass through a fiber-optic splitter having two output branches. The light in one branch would be sent through an atomic cell to a photodiode. The light in the other branch would constitute the microwave-modulated optical output. Part of the light leaving the atomic cell could also be used to stabilize the laser at a frequency in the vicinity of the desired hyperfine or other quantum transition. The

  3. A pressure scanning Fabry-Perot magnetometer.

    NASA Technical Reports Server (NTRS)

    Fay, T. D.; Wyller, A. A.

    1971-01-01

    Description of an oscillating magnetic analyzer (KDP crystal plus Glan-Thompson prism) coupled to an echelle-interferometer spectrograph, and of single-slit magnetometer which by pressure variations can be made to scan the entire profiles of the circularly and linearly polarized Zeeman components. Freon gas is used as the scanner gas with wavelength displacements of 0.02 A per 0.1 in. Hg pressure change at the NaD lines. The available scan range is 15 A in the visual spectral region.

  4. Investigation of the Forces Acting on Gliders in Automobile-pulley-winch and Airplane Towed Flight

    NASA Technical Reports Server (NTRS)

    Klemperer, W B

    1942-01-01

    The magnitude, the direction, and the fluctuation of towing forces exerted upon gliders by towing them aloft behind an automobile, by means of a winch, and by airplane were measured under a variety of conditions covering a range from gentle to severe types of operation. For these tests the towing forces did not exceed 92 percent of the gross weight of the glider. The results indicate that in pulley and winch towing the towing forces are of about the same magnitude as in automobile towing. Speed increases in the accelerated phases of the towing jerks encountered in airplane towing can readily become critical as speeds in excess of placard speeds can be attained. Passage through the slipstream of the towing airplane can be equivalent to a severe gust that, at high speed, may impose high wing loads and require large control moments.

  5. Juno Magnetometer Observations in the Earth's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Connerney, J. E.; Oliversen, R. J.; Espley, J. R.; MacDowall, R. J.; Schnurr, R.; Sheppard, D.; Odom, J.; Lawton, P.; Murphy, S.; Joergensen, J. L.; Joergensen, P. S.; Merayo, J. M.; Denver, T.; Bloxham, J.; Smith, E. J.; Murphy, N.

    2013-12-01

    The Juno spacecraft enjoyed a close encounter with Earth on October 9, 2013, en route to Jupiter Orbit Insertion (JOI) on July 5, 2016. The Earth Flyby (EFB) provided a unique opportunity for the Juno particles and fields instruments to sample mission relevant environments and exercise operations anticipated for orbital operations at Jupiter, particularly the period of intense activity around perijove. The magnetic field investigation onboard Juno is equipped with two magnetometer sensor suites, located at 10 and 12 m from the spacecraft body at the end of one of the three solar panel wings. Each contains a vector fluxgate magnetometer (FGM) sensor and a pair of co-located non-magnetic star tracker camera heads which provide accurate attitude determination for the FGM sensors. This very capable magnetic observatory sampled the Earth's magnetic field at 64 vector samples/second throughout passage through the Earth's magnetosphere. We present observations of the Earth's magnetic field and magnetosphere obtained throughout the encounter and compare these observations with those of other Earth-orbiting assets, as available, and with particles and fields observations acquired by other Juno instruments operated during EFB.

  6. The Search Coil Magnetometer for THEMIS

    NASA Astrophysics Data System (ADS)

    Roux, A.; Le Contel, O.; Coillot, C.; Bouabdellah, A.; de La Porte, B.; Alison, D.; Ruocco, S.; Vassal, M. C.

    2008-12-01

    THEMIS instruments incorporate a tri-axial Search Coil Magnetometer (SCM) designed to measure the magnetic components of waves associated with substorm breakup and expansion. The three search coil antennas cover the same frequency bandwidth, from 0.1 Hz to 4 kHz, in the ULF/ELF frequency range. They extend, with appropriate Noise Equivalent Magnetic Induction (NEMI) and sufficient overlap, the measurements of the fluxgate magnetometers. The NEMI of the searchcoil antennas and associated pre-amplifiers is smaller than 0.76 pT /sqrt{Hz} at 10 Hz. The analog signals produced by the searchcoils and associated preamplifiers are digitized and processed inside the Digital Field Box (DFB) and the Instrument Data Processing Unit (IDPU), together with data from the Electric Field Instrument (EFI). Searchcoil telemetry includes waveform transmission, FFT processed data, and data from a filter bank. The frequency range covered depends on the available telemetry. The searchcoils and their three axis structures have been precisely calibrated in a calibration facility, and the calibration of the transfer function is checked on board, usually once per orbit. The tri-axial searchcoils implemented on the five THEMIS spacecraft are working nominally.

  7. Curtiss JN-4H Towing Model Wing

    NASA Technical Reports Server (NTRS)

    1921-01-01

    In 1919 the NACA Langley laboratory received its first three research aircraft which were Curtiss JN-4Hs borrowed from the US Army Air Service at Langley Field. One of the first research projects of the laboratory initiated that year was a flight investigation of the lift and drag characteristics of the JN-4H. One of the objectives of the flight tests was to obtain data for correlation with wind-tunnel test results measured at MIT and to aid in the derivation of techniques for extrapolation of model results to full-scale conditions. In a pioneering aeronautical effort in 1920, pressure orifices were installed in the horizontal tail of one of the Jennies and connected to glass manometers for pressure measurements that could be photographed in flight. The NACA also used the aircraft in some of the earliest experiments on maneuverability in 1921. In addition to serving as test subjects, the aircraft were used for measurements of aerodynamic behavior of aircraft components. In this photograph made in 1921, one of the JN- 4Hs is towing a model of an aircraft wing to obtain lift and drag information for comparison to tunnel results. All three Jenny aircraft departed Langley in 1923. Reference: 'Flying the Frontiers: NACA and NASA Experimental Aircraft' by Arthur Pearcy. Naval Institute Press, 1993. ISBN 1-55750-258-7

  8. A 16-channel high-Tc SQUID-magnetometer system for magnetocardiogram mapping

    NASA Astrophysics Data System (ADS)

    Yokosawa, Koichi; Tsukamoto, Akira; Suzuki, Daisuke; Kandori, Akihiko; Miyashita, Tsuyoshi; Ogata, Kuniomi; Seki, Yusuke; Tsukada, Keiji

    2003-12-01

    A compact, light and easy-to-handle magnetocardiograph (MCG) has been developed. The MCG consists of a sensor array with superconducting-quantum-interference-device magnetometers made of a high-critical temperature superconductor, arranged in a 4 × 4 matrix, and operated in a vertical magnetically shielding cylinder (1.7 m high and 1 m in diameter). Each magnetometer is paired with each of its adjacent magnetometers, and the difference between the respective outputs provides us with a measure of magnetic gradient. This configuration for the electronic gradiometers cancels out the environmental magnetic field noise within the shielding cylinder. We use the data from the multiple gradiometers to construct a current arrow map that describes the distribution of original current vectors in the area being measured. We used the fabricated MCG to record magnetocardiograms of healthy volunteers. The smallest signals, i.e., the P-waves, were clearly detected without averaging. The current arrow maps obtained from the single-beat magnetocardiograms indicate the feasibility of clinical application of this MCG.

  9. An Optically Pumped Magnetometer Working in the Light-Shift Dispersed Mz Mode.

    PubMed

    Schultze, Volkmar; Schillig, Bastian; IJsselsteijn, Rob; Scholtes, Theo; Woetzel, Stefan; Stolz, Ronny

    2017-03-10

    We present an optically pumped magnetometer working in a new operational mode-the light-shift dispersed Mz (LSD-Mz) mode. It is realized combining various features; (1) high power off-resonant optical pumping; (2) Mz configuration, where pumping light and magnetic field of interest are oriented parallel to each other; (3) use of small alkali metal vapor cells of identical properties in integrated array structures, where two such cells are pumped by circularly polarized light of opposite helicity; and (4) subtraction of the Mz signals of these two cells. The LSD-Mz magnetometer's performance depends on the inherent and very complex interplay of input parameters. In order to find the configuration of optimal magnetometer resolution, a sensitivity analysis of the input parameters by means of Latin Hypercube Sampling was carried out. The resulting datasets of the multi-dimensional parameter space exploration were assessed by a subsequent physically reasonable interpretation. Finally, the best shot-noise limited magnetic field resolution was determined within that parameter space. As the result, using two 50 mm3 integrated vapor cells a magnetic field resolution below 10 fT/√Hz at Earth's magnetic field strength is possible.

  10. Analysing Harmonic Motions with an iPhone's Magnetometer

    ERIC Educational Resources Information Center

    Yavuz, Ahmet; Temiz, Burak Kagan

    2016-01-01

    In this paper, we propose an experiment for analysing harmonic motion using an iPhone's (or iPad's) magnetometer. This experiment consists of the detection of magnetic field variations obtained from an iPhone's magnetometer sensor. A graph of harmonic motion is directly displayed on the iPhone's screen using the "Sensor Kinetics"…

  11. Internet Access to ISEE-1 and 2 Magnetometer Data

    NASA Technical Reports Server (NTRS)

    1997-01-01

    It is reported that the entire ISEE-1 and -2 magnetometer data are placed on-line, using an 8 Gbyte disk drive. The data are stored at 4-s and 60-s resolution. Also, an interactive world wide web page, which allows to plot, on request, any interval for which magnetometer data are available, is developed.

  12. Tow collapse model for compression strength of textile composites

    SciTech Connect

    Emehel, T.C.; Shivakumar, K.N.

    1995-12-31

    The unidirectional composite compression strength model based on microbuckling of fibers embedded in a rigid-plastic matrix was extended to multiaxial laminates and textile composites. The resulting expression is a function of matrix yield strength under the fiber constraint, fiber misalignment angle, fiber volume fraction, and the area fractions of various sets of inclined tows. The analysis was verified by experimentation. Compression tests were conducted on laminated, three-dimensional triaxially braided and orthogonally woven composites using the IITRI test specimen. The laminate specimens were made up of AS4/3501-6 graphite/epoxy composite with (0){sub 24}, (0/30/0/{minus}30){sub 3S}, and ((0/90)6/0){sub S} stacking sequence. Textile composites were made of BASF G30-500 graphite fiber tows (tow size is 6K) and Dow Chemicals Tactix 123 matrix. Fiber preform architecture of braided and woven composites before resin consolidation was 0/{+-}17 and 0/90, respectively and after consolidation it was about (7/{+-}20) and (5/90/90), respectively. The analysis agreed reasonably well with the test data for all cases considered. The axial fiber/tow misalignment angle for laminated, braided, and woven composites were about 4, 7, and 5 degrees, respectively. The compression strength was found to be strongly dependent on the percentage of axial tows and its misalignment angle. A small variation in the off-axis fiber/tow orientation had marginal effect on the compression strength. Hence, the off axis tow misalignment angle can be assumed to be same as the initial laminate or the two orientation angle.

  13. Stand-alone WIreless Magnetometer System: Concept Design and Development Status

    NASA Astrophysics Data System (ADS)

    Anderson, B. J.; Carkhuff, B. G.; Rhodes, E.; Korth, H.

    2007-12-01

    The Stand-alone WIreless Magnetometer System (SWIMS) is intended to serve as a technology suitable for large scale deployment for magnetometer networks in sub-auroral latitudes with minimal logistical support and maintenance. SWIMS is based on a new magnetometer developed and licensed by JHU/APL. A SWIMS installation will consist of up to three solar/battery powered Sensor Modules (SM) each equipped with a new Mirror Image Differential Induction Amplitude Magnetometer (MIDIAM). The SMs are linked via wireless, radio frequency (RF) connection to a Central Node (CN). The RF link allows wireless installation over distances up to 300 meters between SMs. The CN may communicate either via land lines or wireless links to a central data facility. Because each SM is wireless, SWIMS can use more than one SM at a single site to discriminate against local noise sources. The present project objective is to develop a prototype SWIMS system of three SMs communicating via local RF link to a CN. The MIDIAM has yielded sub-nT performance with less than 1W power consumption in continuous operation. A conceptual system design using commercial solar/batter power system and RF communication components has been developed that is expected to achieve continuous operation at 1- second or higher rate sampling using a moderately sized solar cell array, 12" x 18", and a 6"x6"x4" AGM battery (144 W-hour). By monitoring the battery depth of discharge and duty cycling MIDIAM as required if incident effective power is low due to inclement conditions, the SM is expected to support continuous unattended operation with no coarser than one sample per minute on as little as four hours of sunlight every ten days.

  14. Fine structure of methane hydrate-bearing sediments on the Blake Outer ridge as determined from deep-tow multichannel seismic data. (Reannouncement with new availability information). Final report

    SciTech Connect

    Rowe, M.M.; Gettrust, J.F.

    1993-01-01

    High-resolution, deep-tow multichannel seismic data are used to investigate the detailed structure of sediments containing methane hydrate. These data support thick, laterally extensive layers of methane hydrate-bearing sediment underlain by a bottom simulating reflector (BSR) and spatially discontinuous zones of hydrate within the sediments above the BSR depth where no BSR is present. These data resolve normal faults which extend from the surface through the BSR with apparent offsets of up to 20 m. A phase inversion identified at the top of the BSR shows that the material immediately beneath the BSR has anomalously low velocity, consistent with a layer of sediment containing free methane gas. The fault offsets along the BSR and consistent with a pressure change of approx. 200 kPa (approx. 2 bars) across the fault zone.... Directional ambient noise, Bottom scattering, Deep-towed array geophysical system, Towed array, Ocean-bottom seismometer

  15. Drag Characteristics of Several Towed Decelerator Models at Mach 3

    NASA Technical Reports Server (NTRS)

    1970-01-01

    Drag Characteristics of Several Towed Decelerator Models at Mach 3. An investigation has been made to determine the possibility of using toroid-membrane and wide-angle conical shapes as towed decelerators. Parameter variations were investigated which might render toroid-membrane models and wide-angle- cone models stable without loss of the high drag coefficients obtainable with sting-mounted models. The parameters varied included location of center of gravity, location of the pivot between the towline and the model, and configuration modifications of the aft end as the addition of a corner radius and the addition of a skirt. The toroid membrane can be made into a stable towed decelerator with a suitable configuration modification of the aft end. [Entire movie available on DVD from CASI as Doc ID 20070031013. Contact help@sti.nasa.gov

  16. Structural Assessment of Advanced Composite Tow-Steered Shells

    NASA Technical Reports Server (NTRS)

    Wu, K. Chauncey; Stanford, Bret K.; Hrinda, Glenn A.; Wang, Zhuosong; Martin, Robert a.; Kim, H. Alicia

    2013-01-01

    The structural performance of two advanced composite tow-steered shells, manufactured using a fiber placement system, is assessed using both experimental and analytical methods. The fiber orientation angles vary continuously around the shell circumference from 10 degrees on the shell crown and keel, to 45 degrees on the shell sides. The two shells differ in that one shell has the full 24-tow course applied during each pass of the fiber placement system, while the second shell uses the fiber placement system s tow drop/add capability to achieve a more uniform shell wall thickness. The shells are tested in axial compression, and estimates of their prebuckling axial stiffnesses and bifurcation buckling loads are predicted using linear finite element analyses. These preliminary predictions compare well with the test results, with an average agreement of approximately 10 percent.

  17. Models in towing basins/design of floats for seaplanes

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Towing carriage gear housing in the Tow Tank. Starr Truscott described the Towing Carriage in NACA TR No. 470: ' The structure of the towing carriage is of carbon-steel tube, with all joints welded. In order to insure accuracy of alinement (sic.) in the girders forming the car structure, the ends of all the tubes meeting at a joint were milled to fit snugly before welding and all welding was done with the structure in a massive jig. The gear cases also are of welded construction.' (p. 537) The Tow Tank was designed by Starr Truscott. Construction was authorized in March 1929 and was dedicated on May 27, 1931 during the Annual Manufacturer's Inspection meeting. The tank's initial cost was $649,000. It was used by the NACA to study hydrodynamics problems until 1959 when the facility was turned over to the U.S. Navy. The tank was extended to 2960 in 1936. In addition to increasing the length of the tank, a new high-speed (80-mph) carriage was installed in 1936-1937.Construction of pontoon hull model to be tested in Tow Tank No. 1. This is a 1/6 full size model of the hull of a Navy PH-1 flying boat. Two typical tests were conducted and included in the first report describing the High-Speed Towing Basin. From TR 470: 'A survey of the information available regarding the application of the results of tests of models in towing basins to the design of floats for seaplanes was made by the National Advisory Committee for Aeronautics in 1929. It was found that the development of flying boats and seaplanes had been assisted very much in the United States, and possibly more in other countries, by tests of models in towing basins or tanks. Some tanks already existed which were designed especially for testing models of seaplane floats and the construction of other tanks for this special purpose was projected. There was no such tank in the United States; in fact, there were only two tanks, both constructed before the appearance of the seaplane and designed originally to test

  18. High transition-temperature SQUID magnetometers and practical applications

    SciTech Connect

    Dantsker, Eugene

    1997-05-01

    The design, fabrication and performance of SQUID magnetometers based on thin films of the high-transition temperature superconductor YBa2Cu3O7-x (YBCO) are described. Essential to the achieving high magnetic field resolution at low frequencies is the elimination of 1/f flux noise due to thermally activated hopping of flux vortices between pinning sites in the superconducting films. Through improvements in processing, 1/f noise in single layer YBCO thin films and YBCO-SrTiO3-YBCO trilayers was systematically reduced to allow fabrication of sensitive SQUID magnetometers. Both single-layer directly coupled SQUID magnetometers and multilayer magnetometers were fabricated, based on the dc SQUID with bicrystal grain boundary Josephson junctions. Multilayer magnetometers had a lower magnetic field noise for a given physical size due to greater effective sensing areas. A magnetometer consisting of a SQUID inductively coupled to the multiturn input coil of a flux transformer in a flip-chip arrangement had a field noise of 27 fT Hz-1/2 at 1 Hz and 8.5 fT Hz-1/2 at 1 kHz. A multiloop multilayer SQUID magnetometer had a field noise of 37 fT Hz-1/2 at 1 Hz and 18 fT Hz-1/2 at 1 kHz. A three-axis SQUID magnetometer for geophysical applications was constructed and operated in the field in the presence of 60 Hz and radiofrequency noise. Clinical quality magnetocardiograms were measured using multilayer SQUID magnetometers in a magnetically shielded room.

  19. Air-Sea Interaction Measurements from the Controlled Towed Vehicle

    NASA Astrophysics Data System (ADS)

    Khelif, D.; Bluth, R. T.; Jonsson, H.; Barge, J.

    2014-12-01

    The Controlled Towed Vehicle (CTV) uses improved towed drone technology to actively maintain via a radar altimeter and controllable wing a user-set height that can be as low as the canonical reference height of 10 m above the sea surface. After take-off, the drone is released from the tow aircraft on a ~700-m stainless steel cable. We have instrumented the 0.23 m diameter and 2.13 m long drone with high fidelity instruments to measure the means and turbulent fluctuations of 3-D wind vector, temperature, humidity, pressure, CO2 and IR sea surface temperature. Data are recorded internally at 40 Hz and simultaneously transmitted to the tow aircraft via dedicated wireless Ethernet link. The CTV accommodates 40 kg of instrument payload and provides it with 250 W of continuous power through a ram air propeller-driven generator. Therefore its endurance is only limited by that of the tow aircraft.We will discuss the CTV development, the engineering challenges and solutions that have been successfully implemented to overcome them. We present results from recent flights as low as 9 m over the coastal ocean and comparisons of profiles and turbulent fluxes from the CTV and the tow aircraft. Manned aircraft operation at low-level boundary-layer flights is very limited. Dropsondes and UAS (Unmanned Aerial Systems) and UAS are alternates for measurements near the ocean surface. However, dropsondes have limited sensor capability and do not measure fluxes, and most present UAS vehicles do not have the payload and power capacity nor the low-flying ability in high winds over the oceans. The CTV therefore, fills a needed gap between the dropsondes, in situ aircraft, and UAS. The payload, capacity and power of the CTV makes it suitable for a variety of atmospheric research measurements. Other sensors to measure aerosol, chemistry, radiation, etc., could be readily accommodated in the CTV.

  20. The dynamics of the plasmasphere boundary layer as determined by ground magnetometers, satellite observations, and modeling

    NASA Astrophysics Data System (ADS)

    Zesta, E.; Boudouridis, A.; Yizengaw, E.; Jorgensen, A. M.; Carranza-fulmer, T. L.; Moldwin, M.; Mann, I. R.; Chi, P. J.

    2013-12-01

    The plasmasphere boundary layer (PBL) separates the cold and dense plasmaspheric plasma from the more tenuous and hot plasma sheet plasma and organizes the spatial distribution of ULF and VLF waves that can contribute to acceleration or loss processes of radiation belt particles through wave-particle interactions. The PBL has been traditionally determined by in situ observations and can be given by empirical models. Recent work has shown that a mid-latitude chain of well-spaced ground magnetometers can also determine the PBL location. Spectral properties, like the cross-phase reversal in the standard field-line resonance (FLR) determination between two stations closely aligned in latitude, have been shown to indicate the presence of a sharp PBL. We merge data from many ground magnetometer pairs from the SAMBA (South American Meridional B-field Array), McMAC (Mid continent Magnetoseismic Chain), and CARISMA (Canadian Array for Realtime Investigations of Magnetic Activity) chains to provide the best available spatial coverage in L values spanning the plasmasphere and PBL, for a range of dynamic states (L=1.6 to greater than 5). The PBL location is identified as the L value of the station pair for which a reverse phase difference is observed in the standard FLR determination. We compare the FLR determined PBL with the trough boundary determined by GPS Total Electron Content (TEC) analysis and with model PBL. Initial results demonstrate that the PBL as identified by the reverse phase differences is in general agreement with TEC identifications and reasonable agreement with models. Reverse Phase Differences are regularly observed at the L range of 2.7 to 3.7 and are highly correlated with Dst and Kp, as determined by daily correlations. We further examine the more detailed time sequence of the PBL dynamics by focusing on key periods around storms preceded by quiet periods, and by using the full L range of the ground magnetometer pairs.

  1. Search Coil vs. Fluxgate Magnetometer Measurements at Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Wilson, L.B., III

    2012-01-01

    We present magnetic field observations at interplanetary shocks comparing two different sample rates showing significantly different results. Fluxgate magnetometer measurements show relatively laminar supercritical shock transitions at roughly 11 samples/s. Search coil magnetometer measurements at 1875 samples/s, however, show large amplitude (dB/B as large as 2) fluctuations that are not resolved by the fluxgate magnetometer. We show that these fluctuations, identified as whistler mode waves, would produce a significant perturbation to the shock transition region changing the interpretation from laminar to turbulent. Thus, previous observations of supercritical interplanetary shocks classified as laminar may have been under sampled.

  2. Analysing harmonic motions with an iPhone’s magnetometer

    NASA Astrophysics Data System (ADS)

    Yavuz, Ahmet; Kağan Temiz, Burak

    2016-05-01

    In this paper, we propose an experiment for analysing harmonic motion using an iPhone’s (or iPad’s) magnetometer. This experiment consists of the detection of magnetic field variations obtained from an iPhone’s magnetometer sensor. A graph of harmonic motion is directly displayed on the iPhone’s screen using the Sensor Kinetics application. Data from this application was analysed with Eureqa software to establish the equation of the harmonic motion. Analyses show that the use of an iPhone’s magnetometer to analyse harmonic motion is a practical and effective method for small oscillations and frequencies less than 15-20 Hz.

  3. Instrumentation requirements for small scale towed temperature measurements

    NASA Astrophysics Data System (ADS)

    Dugan, J. P.; Morris, W. D.

    1984-03-01

    Measurements of horizontal ocean temperature structure are difficult to obtain by towing sensors from research vessels because the tow cable induces sensor platform motions which contaminate the data. In this report, temperature data which previously were acquired in the thermocline with special care are used to specify the acceptable level of motion and to prescribe appropriate sensor noise levels. In the swell-induced ship motion band, for example, the rms vertical displacements of the sensors should be less than several centimeters and temperature sensors should resolve fluctuations of one millidegree Celsius in regions of high (approx 0.1 C/m) temperature gradient.

  4. 49 CFR 393.71 - Coupling devices and towing methods, driveaway-towaway operations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... ball-and-socket type coupling device may be used in any combination. (3) When motor vehicles are towed... motor vehicle or motor vehicles may be full-mounted on the structure of a towing vehicle engaged in any... motor vehicle or motor vehicles may be full-mounted on the structure of towed vehicles engaged in...

  5. 49 CFR 393.70 - Coupling devices and towing methods, except for driveaway-towaway operations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 5 2011-10-01 2011-10-01 false Coupling devices and towing methods, except for... MOTOR CARRIER SAFETY REGULATIONS PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Coupling Devices and Towing Methods § 393.70 Coupling devices and towing methods, except for driveaway-towaway operations....

  6. 49 CFR 393.71 - Coupling devices and towing methods, driveaway-towaway operations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false Coupling devices and towing methods, driveaway... SAFETY REGULATIONS PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Coupling Devices and Towing Methods § 393.71 Coupling devices and towing methods, driveaway-towaway operations. (a) Number in...

  7. 49 CFR 393.70 - Coupling devices and towing methods, except for driveaway-towaway operations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 5 2013-10-01 2013-10-01 false Coupling devices and towing methods, except for... MOTOR CARRIER SAFETY REGULATIONS PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Coupling Devices and Towing Methods § 393.70 Coupling devices and towing methods, except for driveaway-towaway operations....

  8. 49 CFR 393.71 - Coupling devices and towing methods, driveaway-towaway operations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 5 2012-10-01 2012-10-01 false Coupling devices and towing methods, driveaway... SAFETY REGULATIONS PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Coupling Devices and Towing Methods § 393.71 Coupling devices and towing methods, driveaway-towaway operations. (a) Number in...

  9. 49 CFR 393.70 - Coupling devices and towing methods, except for driveaway-towaway operations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 5 2012-10-01 2012-10-01 false Coupling devices and towing methods, except for... MOTOR CARRIER SAFETY REGULATIONS PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Coupling Devices and Towing Methods § 393.70 Coupling devices and towing methods, except for driveaway-towaway operations....

  10. 49 CFR 393.70 - Coupling devices and towing methods, except for driveaway-towaway operations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false Coupling devices and towing methods, except for... MOTOR CARRIER SAFETY REGULATIONS PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Coupling Devices and Towing Methods § 393.70 Coupling devices and towing methods, except for driveaway-towaway operations....

  11. 46 CFR 11.464 - Requirements for endorsements as master of towing vessels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Requirements for endorsements as master of towing....464 Requirements for endorsements as master of towing vessels. (a) If you would like to obtain an endorsement as master of towing vessels with a route listed in column 1 of table 11.464(a) of this...

  12. Multi-channel atomic magnetometer for magnetoencephalography: a configuration study.

    PubMed

    Kim, Kiwoong; Begus, Samo; Xia, Hui; Lee, Seung-Kyun; Jazbinsek, Vojko; Trontelj, Zvonko; Romalis, Michael V

    2014-04-01

    Atomic magnetometers are emerging as an alternative to SQUID magnetometers for detection of biological magnetic fields. They have been used to measure both the magnetocardiography (MCG) and magnetoencephalography (MEG) signals. One of the virtues of the atomic magnetometers is their ability to operate as a multi-channel detector while using many common elements. Here we study two configurations of such a multi-channel atomic magnetometer optimized for MEG detection. We describe measurements of auditory evoked fields (AEF) from a human brain as well as localization of dipolar phantoms and auditory evoked fields. A clear N100m peak in AEF was observed with a signal-to-noise ratio of higher than 10 after averaging of 250 stimuli. Currently the intrinsic magnetic noise level is 4fTHz(-1/2) at 10Hz. We compare the performance of the two systems in regards to current source localization and discuss future development of atomic MEG systems.

  13. Combined Electromagnetic and Magnetometer Data Acquisition and Processing

    DTIC Science & Technology

    2004-10-27

    Mag1 Mag2 Mag3 Mag4 Mag5 Figure 33: 15 Hz noise on all five magnetometers, McKinley Test Range, acquired with system roughly 100 yards from a...ue , G am m a Mag1 Mag2 Mag3 Mag4 Mag5 Figure 34: 15 Hz noise on all five magnetometers, McKinley Test Range, acquired with system roughly 1000

  14. Optofluidic magnetometer developed in a microstructured optical fiber.

    PubMed

    Candiani, A; Konstantaki, M; Margulis, W; Pissadakis, S

    2012-11-01

    A directional, in-fiber optofluidic magnetometer based on a microstructured optical fiber (MOF) Bragg-grating infiltrated with a ferrofluidic defect is presented. Upon application of a magnetic field, the ferrofluidic defect moves along the length of the MOF Bragg grating, modifying its reflection spectrum. The magnetometer is capable of measuring magnetic fields from 317 to 2500 G. The operational principle of such in-fiber magnetic field probe allows the elaboration of directional measurements of the magnetic field flux.

  15. Detection of J-coupling using atomic magnetometer

    SciTech Connect

    Ledbetter, Micah P.; Crawford, Charles W.; Wemmer, David E.; Pines, Alexander; Knappe, Svenja; Kitching, John; Budker, Dmitry

    2015-09-22

    An embodiment of a method of detecting a J-coupling includes providing a polarized analyte adjacent to a vapor cell of an atomic magnetometer; and measuring one or more J-coupling parameters using the atomic magnetometer. According to an embodiment, measuring the one or more J-coupling parameters includes detecting a magnetic field created by the polarized analyte as the magnetic field evolves under a J-coupling interaction.

  16. Ultra-sensitive Magnetic Microscopy with an Atomic Magnetometer

    SciTech Connect

    Kim, Young Jin

    2015-08-19

    The PowerPoint presentation focused on research goals, specific information about the atomic magnetometer, response and resolution factors of the SERF magnetometer, FC+AM systems, tests of field transfer and resolution on FC, gradient cancellation, testing of AM performance, ideas for a multi-channel AM, including preliminary sensitivity testing, and a description of a 6 channel DAQ system. A few ideas for future work ended the presentation.

  17. Ultrasensitive Magnetometer using a Single Atom

    NASA Astrophysics Data System (ADS)

    Baumgart, I.; Cai, J.-M.; Retzker, A.; Plenio, M. B.; Wunderlich, Ch.

    2016-06-01

    Precision sensing, and in particular high precision magnetometry, is a central goal of research into quantum technologies. For magnetometers, often trade-offs exist between sensitivity, spatial resolution, and frequency range. The precision, and thus the sensitivity of magnetometry, scales as 1 /√{T2 } with the phase coherence time T2 of the sensing system playing the role of a key determinant. Adapting a dynamical decoupling scheme that allows for extending T2 by orders of magnitude and merging it with a magnetic sensing protocol, we achieve a measurement sensitivity even for high frequency fields close to the standard quantum limit. Using a single atomic ion as a sensor, we experimentally attain a sensitivity of 4.6 pT /√{Hz } for an alternating-current magnetic field near 14 MHz. Based on the principle demonstrated here, this unprecedented sensitivity combined with spatial resolution in the nanometer range and tunability from direct current to the gigahertz range could be used for magnetic imaging in as of yet inaccessible parameter regimes.

  18. Monitoring space weather with the GOES magnetometers

    NASA Astrophysics Data System (ADS)

    Singer, Howard; Matheson, Lorne; Grubb, Richard; Newman, Ann; Bouwer, David

    1996-10-01

    Magnetic field measurements have been made form geosynchronous orbit for more than 20 years. These measurements are important for monitoring 'space weather' and for providing a unique data base that can be used for improving our knowledge of the Earth's magnetosphere and solar-terrestrial interactions. This paper will focus on the variety of products and services provided by these measurements--those currently available, and those under consideration for the future. The magnetic field assist forecasters in qualitatively assessing the level of geomagnetic disturbance, to interpret changes in energetic particle measurements, to provide data to the National Geophysical Data Center, to support in real-time scientific activities such as rocket launches, and to conduct research for a better understanding of the space environment. One important use of magnetometer data in the Space Environment Center is to alert customers when shocks occur in the solar wind. These shocks have the potential for energizing particles to multi-MeV levels, causing Single Event Upsets in spacecraft electronics, and at lower energy ranges causing deep-dielectric charging that produces spacecraft anomalies. Data from the new GOES-8 and GOES-9 spacecraft will be discussed along with prospects for future products and services.

  19. The Search-Coil Magnetometer for MMS

    NASA Astrophysics Data System (ADS)

    Le Contel, O.; Leroy, P.; Roux, A.; Coillot, C.; Alison, D.; Bouabdellah, A.; Mirioni, L.; Meslier, L.; Galic, A.; Vassal, M. C.; Torbert, R. B.; Needell, J.; Rau, D.; Dors, I.; Ergun, R. E.; Westfall, J.; Summers, D.; Wallace, J.; Magnes, W.; Valavanoglou, A.; Olsson, G.; Chutter, M.; Macri, J.; Myers, S.; Turco, S.; Nolin, J.; Bodet, D.; Rowe, K.; Tanguy, M.; de la Porte, B.

    2016-03-01

    The tri-axial search-coil magnetometer (SCM) belongs to the FIELDS instrumentation suite on the Magnetospheric Multiscale (MMS) mission (Torbert et al. in Space Sci. Rev. (2014), this issue). It provides the three magnetic components of the waves from 1 Hz to 6 kHz in particular in the key regions of the Earth's magnetosphere namely the subsolar region and the magnetotail. Magnetospheric plasmas being collisionless, such a measurement is crucial as the electromagnetic waves are thought to provide a way to ensure the conversion from magnetic to thermal and kinetic energies allowing local or global reconfigurations of the Earth's magnetic field. The analog waveforms provided by the SCM are digitized and processed inside the digital signal processor (DSP), within the Central Electronics Box (CEB), together with the electric field data provided by the spin-plane double probe (SDP) and the axial double probe (ADP). On-board calibration signal provided by DSP allows the verification of the SCM transfer function once per orbit. Magnetic waveforms and on-board spectra computed by DSP are available at different time resolution depending on the selected mode. The SCM design is described in details as well as the different steps of the ground and in-flight calibrations.

  20. Ultrasensitive Magnetometer using a Single Atom.

    PubMed

    Baumgart, I; Cai, J-M; Retzker, A; Plenio, M B; Wunderlich, Ch

    2016-06-17

    Precision sensing, and in particular high precision magnetometry, is a central goal of research into quantum technologies. For magnetometers, often trade-offs exist between sensitivity, spatial resolution, and frequency range. The precision, and thus the sensitivity of magnetometry, scales as 1/sqrt[T_{2}] with the phase coherence time T_{2} of the sensing system playing the role of a key determinant. Adapting a dynamical decoupling scheme that allows for extending T_{2} by orders of magnitude and merging it with a magnetic sensing protocol, we achieve a measurement sensitivity even for high frequency fields close to the standard quantum limit. Using a single atomic ion as a sensor, we experimentally attain a sensitivity of 4.6  pT/sqrt[Hz] for an alternating-current magnetic field near 14 MHz. Based on the principle demonstrated here, this unprecedented sensitivity combined with spatial resolution in the nanometer range and tunability from direct current to the gigahertz range could be used for magnetic imaging in as of yet inaccessible parameter regimes.

  1. Calibrating the Prominence Magnetometer (ProMag)

    NASA Astrophysics Data System (ADS)

    Fox, Lewis; Casini, R.

    2013-07-01

    The Prominence Magnetometer (ProMag) is a dual-channel, dual-beam, slit-scanning, full Stokes spectro-polarimeter designed by the High Altitude Observatory at the National Center for Atmospheric Research (HAO/NCAR) for the study of the magnetism of solar prominences and filaments. It was deployed in August 2009 at the 40 cm coronagraph of the Evans Solar Facility (ESF) of the National Solar Observatory on Sacramento Peak (NSO/SP). In its standard mode of operation it acquires spectro-polarimetric maps of solar targets simultaneously in the two chromospheric lines of He I at 587.6 nm and 1083.0 nm. Since August 2011 ProMag has operated in “patrol mode” with a dedicated observer. We aim to routinely measure the vector magnetic field in prominences. The electro-optic modulator and polarization analyzer are integrated into a single mechanical unit located at the coude feed of the telescope. This location was necessary for proper co-alignment of the dual beams, but complicates the precise polarimeter calibration necessary to achieve the sensitivity required for prominence measurements (< 10^-3). At this sensitivity, small variations in optical alignment can become significant. We present a calibration method for ProMag, using a polarizer and retarder at coronagraph prime focus. Calibrations are recorded before and after observations. We discuss the success of this method and its limitations.

  2. Swarm's Absolute Scalar Magnetometers Burst Mode Results

    NASA Astrophysics Data System (ADS)

    Coisson, P.; Vigneron, P.; Hulot, G.; Crespo Grau, R.; Brocco, L.; Lalanne, X.; Sirol, O.; Leger, J. M.; Jager, T.; Bertrand, F.; Boness, A.; Fratter, I.

    2014-12-01

    Each of the three Swarm satellites embarks an Absolute Scalar Magnetometer (ASM) to provide absolute scalar measurements of the magnetic field with high accuracy and stability. Nominal data acquisition of these ASMs is 1 Hz. But they can also run in a so-called "burst mode" and provide data at 250 Hz. During the commissioning phase of the mission, seven burst mode acquisition campaigns have been run simultaneously for all satellites, obtaining a total of ten days of burs-mode data. These campaigns allowed the identification of issues related to the operations of the piezo-electric motor and the heaters connected to the ASM, that do not impact the nominal 1 Hz scalar data. We analyze the burst mode data to identify high frequency geomagnetic signals, focusing the analysis in two regions: the low latitudes, where we seek signatures of ionospheric irregularities, and the high latitudes, to identify high frequency signals related to polar region currents. Since these campaigns have been conducted during the initial months of the mission, the three satellites where still close to each other, allowing to analyze the spatial coherency of the signals. Wavelet analysis have revealed 31 Hz signals appearing in the night-side in the equatorial region.

  3. Plasmonic fiber-optic vector magnetometer

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaochuan; Guo, Tuan; Zhang, Xuejun; Xu, Jian; Xie, Wenping; Nie, Ming; Wu, Qiang; Guan, Bai-Ou; Albert, Jacques

    2016-03-01

    A compact fiber-optic vector magnetometer based on directional scattering between polarized plasmon waves and ferro-magnetic nanoparticles is demonstrated. The sensor configuration reported in this work uses a short section of tilted fiber Bragg grating (TFBG) coated with a nanometer scale gold film and packaged with a magnetic fluid (Fe3O4) inside a capillary. The transmission spectrum of the sensor provides a fine comb of narrowband resonances that overlap with a broader absorption of the surface plasmon resonance (SPR). The wavelength of the SPR attenuation in transmission shows high sensitivity to slight perturbations by magnetic fields, due to the strong directional scattering between the SPR attenuated cladding modes and the magnetic fluid near the fiber surface. Both the orientation (2 nm/deg) and the intensity (1.8 nm/mT) of magnetic fields can be determined unambiguously from the TFBG spectrum. Temperature cross sensitivity can be referenced out by monitoring the wavelength of the core mode resonance simultaneously.

  4. 20. VIEW TO WEST OF INTERIOR OF CRANEWAY WITH TOW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. VIEW TO WEST OF INTERIOR OF CRANEWAY WITH TOW TRAVELING BRIDGE CRANES (ONE OVERHEAD IN FOREGROUND AND ONE OVERHEAD IN BACKGROUNDS). NOTE WOOD BLOCK PAVING ON THE FLOOR. FIRST FLOOR ASSEMBLY AREA IS THE SPACE IN THE BACKGROUND ON THE RIGHT. - Rosie the Riveter National Historical Park, Ford Assembly Plant, 1400 Harbour Way South, Richmond, Contra Costa County, CA

  5. 76 FR 59415 - Towing Safety Advisory Committee; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-26

    ... public meeting on Thursday, October 20, 2011, in Newport News, Virginia. Two TSAC sub-committees will meet the day before, October 19, 2011. DATES: Two Towing Safety Advisory Committee Sub-committees will... and local government jurisdictions in compliance with FACA. Agenda--October 19, 2011 TSAC...

  6. Field experiments on an intelligent towed vehicle ``Flying Fish``

    SciTech Connect

    Koterayama, W.; Yamaguchi, S.; Nakamura, M.

    1995-12-31

    A depth, pitch and roll controllable towed vehicle, ``Flying Fish`` is being developed to measure the ocean current, temperature, salinity, dissolved oxygen, pH, turbidity, chlorophyll and total inorganic hydrocarbon. The first field experiments on its performance were carried out in the Japan sea last summer. The motion data of the ``Flying Fish`` are compared with those of numerical simulations.

  7. 75 FR 20856 - Towing Safety Advisory Committee; Vacancies

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-21

    ... Advisory Committee (TSAC). This Committee advises the Coast Guard on matters relating to shallow-draft... authority of 33 U.S.C. 1231a and advises the Secretary of Homeland Security on matters relating to shallow... from the Barge and Towing industry (reflecting a regional geographical balance); 1 member from...

  8. Imperfection Insensitivity Analyses of Advanced Composite Tow-Steered Shells

    NASA Technical Reports Server (NTRS)

    Wu, K. Chauncey; Farrokh, Babak; Stanford, Bret K.; Weaver, Paul M.

    2016-01-01

    Two advanced composite tow-steered shells, one with tow overlaps and another without overlaps, were previously designed, fabricated and tested in end compression, both without cutouts, and with small and large cutouts. In each case, good agreement was observed between experimental buckling loads and supporting linear bifurcation buckling analyses. However, previous buckling tests and analyses have shown historically poor correlation, perhaps due to the presence of geometric imperfections that serve as failure initiators. For the tow-steered shells, their circumferential variation in axial stiffness may have suppressed this sensitivity to imperfections, leading to the agreement noted between tests and analyses. To investigate this further, a numerical investigation was performed in this study using geometric imperfections measured from both shells. Finite element models of both shells were analyzed first without, and then, with measured imperfections that were then, superposed in different orientations around the shell longitudinal axis. Small variations in both the axial prebuckling stiffness and global buckling load were observed for the range of imperfections studied here, which suggests that the tow steering, and resulting circumferentially varying axial stiffness, may result in the test-analysis correlation observed for these shells.

  9. 78 FR 20684 - Towing Safety Advisory Committee; Vacancies

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-05

    ... SECURITY Coast Guard Towing Safety Advisory Committee; Vacancies AGENCY: United States Coast Guard. ACTION: Request for applications. SUMMARY: The United States Coast Guard (the Coast Guard) is requesting... Safety Advisory Committee (TSAC). TSAC advises the Coast Guard on matters relating to shallow-...

  10. Full Scale Wind Tunnel and Seaplane Tow Channel

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction progress, aerials of East Area. L5169: Langley's seaplane towing facility (right) and the Full Scale Tunnel (left) were photographed in November of 1930. Photograph published in Winds of Change, 75th Anniversary NASA publication (page 39), by James Schultz.

  11. 33 CFR 164.78 - Navigation under way: Towing vessels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Navigation under way: Towing vessels. 164.78 Section 164.78 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.78 Navigation under...

  12. 33 CFR 164.78 - Navigation under way: Towing vessels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Navigation under way: Towing vessels. 164.78 Section 164.78 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.78 Navigation under...

  13. 33 CFR 164.78 - Navigation under way: Towing vessels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Navigation under way: Towing vessels. 164.78 Section 164.78 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.78 Navigation under...

  14. 33 CFR 164.78 - Navigation under way: Towing vessels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Navigation under way: Towing vessels. 164.78 Section 164.78 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.78 Navigation under...

  15. 33 CFR 164.78 - Navigation under way: Towing vessels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Navigation under way: Towing vessels. 164.78 Section 164.78 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.78 Navigation under...

  16. 18. VIEW OF BALES OF CEDAR TOW (CEDAR SHAVING WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. VIEW OF BALES OF CEDAR TOW (CEDAR SHAVING WITH SAWDUST TUMBLED OUT) SOLD FOR GARDEN AND ANIMAL BEDDING, AND OTHER AGRICULTURAL USES; TUMBLER IS CYLINDRICAL MACHINE TO LEFT - Lester Shingle Mill, 1602 North Eighteenth Street, Sweet Home, Linn County, OR

  17. An improved Overhauser magnetometer for Earth's magnetic field observation

    NASA Astrophysics Data System (ADS)

    Fan, Shifang; Chen, Shudong; Zhang, Shuang; Guo, Xin; Cao, Qiong

    2016-09-01

    Overhauser magnetometer is a kind of high-precision devices for magnetostatic field measurement. It is widely used in geological survey, earth field variations, UXO detection etc. However, the original Overhauser magnetometer JOM-2 shows great shortcomings of low signal to noise ratio (SNR) and high power consumption, which directly affect the performance of the device. In order to increase the sensitivity and reduce power consumption, we present an improved Overhauser magnetometer. Firstly, compared with the original power board which suffers from heavy noise for improper EMC design, an improved power broad with 20mV peak to peak noise is presented in this paper. Then, the junction field effect transistor (JFET) is used as pre-amplifier in our new design, to overcome the higher current noise produced by the original instrumentation amplifier. By adjusting the parameters carefully low noise factor down to 0.5 dB can be obtained. Finally, the new architecture of ARM + CPLD is adopted to replace the original one with DSP+CPLD. So lower power consumption and greater flash memory can be realized. With these measures, an improved Overhauser magnetometer with higher sensitivity and lower power consumption is design here. The experimental results indicate that the sensitivity of the improved Overhauser magnetometer is 0.071nT, which confirms that the new magnetometer is sensitive to earth field measurement.

  18. Overhauser magnetometer sensor design for magnetic field observation

    NASA Astrophysics Data System (ADS)

    Li, Zan; Chen, Shudong; Zhang, Shuang; Guo, Xin; Cao, Qiong

    2016-10-01

    The Overhauser magnetometer, with its unique set of advantages, such as low power consumption, high precision and fast recording ability has been widely used in geophysical mineral and oil exploration, archeology, environmental survey, ordnance and weapons detection (UXO) and other earth science applications. Compared with the traditional proton magnetometer, which suffers from high power consumption and low precision, the Overhauser magnetometer excite the free radical solution in a cavity with RF signal to enhance nuclear magnetic resonance (NMR). Thus, RF resonator plays a crucial role in reducing power consumption and improving the accuracy of Overhauser magnetometer. There are a wide variety of resonators, but only two of them are chosen for Overhauser magnetometer: birdcage coil and coaxial resonator. In order to get the best RF cavity for Overhauser magnetometer sensor, both resonators are investigated here. Firstly, parameters of two RF resonators are calculated theoretically and simulated with Ansoft HFSS. The results indicate that birdcage coil is characterized by linear polarization while coaxial resonator is characterized by circular polarization. Besides, all RF fields are limited inside of the coaxial resonator while distributed both inside and outside of the birdcage coil. Then, the two resonators are practically manufactured based on the theoretical design. And the S-parameter and Smith chart of these resonators are measured with Agilent 8712ES RF network analyzer. The measured results indicate that the coaxial resonator has a much higher Q value(875) than the birdcage coil(70). All these results reveal a better performance for coaxial resonator. Finally, field experimental shows 0.074nT sensitivity for Overhauser magnetometer with coaxial resonator.

  19. Thermomechanical Characterization of SiC Fiber Tows and Implications for CMC

    NASA Technical Reports Server (NTRS)

    Yun, H. M.; DiCarlo, J. A.

    1999-01-01

    In order to better understand SiC fiber behavior within CMC microstructures, mechanical tests were performed on multifilament tows consisting of different types of as produced and pretreated fibers. Tensile strengths of tows and single fibers were measured at room temperature for nonstoichiometric Hi-Nicalon and ZMI fibers and for stoichiometric Hi-Nicalon-S, Tyranno SA. and Sylramic fibers. Based on simple bundle theory, measured strengths for as-produced and sized tows were in general agreement with the single fiber results. However, after sizing removal under inert conditions, tow strengths for the coarser grained stoichiometric fibers were typically lower than those predicted from individual fiber data. This effect is attributed to enhanced fiber-fiber mechanical interaction caused by sizing removal from the rough surfaces of these fibers. In support of this, tow strengths remained high for those fiber types with fine grains or excess surface carbon; and, when re-coated with a BN interphase coating, tow strengths for the coarser grained fibers returned to their as-produced values. When the tows were pretreated in air at intermediate temperatures, tow strengths decreased in a manner that could be correlated with the oxidation characteristics of each fiber type as measured by thermogravimetric analysis. The creep and rupture properties of Hi-Nicalon and Sylramic tows were also measured in air and argon from 1200 to 1400 C. Although displaying transient and environmental effects similar to single fibers, the tows crept faster at short times and slower at long times. This resulted in the tow rupture strengths at long time being much greater than the rupture strengths of single fibers. The CMC implications of the tow results are discussed, as well as the benefits and limitations of tow testing.

  20. Human MCG measurements with a high-sensitivity potassium atomic magnetometer.

    PubMed

    Kamada, K; Ito, Y; Kobayashi, T

    2012-06-01

    Measuring biomagnetic fields, such as magnetocardiograms (MCGs), is important for investigating biological functions. To address to this need, we developed an optically pumped atomic magnetometer. In this study, human MCGs were acquired using a potassium atomic magnetometer without any modulating systems. The sensitivity of the magnetometer is comparable to that of high-T(c) superconducting quantum interference devices (SQUIDs) and is sufficient for acquiring human MCGs. The activity of a human heart estimated from the MCG maps agrees well with that measured with SQUID magnetometers. Thus, our magnetometer produces reliable results, which demonstrate the potential of our atomic magnetometer for biomagnetic measurements.

  1. A towed airborne platform for turbulence measurements over the ocean

    NASA Astrophysics Data System (ADS)

    Friehe, Carl; Khelif, Djamal

    2008-11-01

    Measurements of wind stress and associated heat and mass fluxes (water vapor and CO2) down to ˜10 meters height over the ocean are required to establish parameterizations for wave, weather, hurricane and climate models. At high winds and accompanying sea states, such measurements are difficult or impossible. A new airborne instrumented towed platform has been developed that allows measurements down to 10 meters under radar-altitude control while the tow aircraft is safely above. Measurements include the three components of the wind, temperature, humidity, infrared surface temperature, CO2, and motion and navigational parameters. The bandwidth of the sensors allows calculation of the Reynolds averaged covariance's of stress and sensible heat and evaporation fluxes. Results are compared to equivalent measurements made with an instrumented aircraft. We would like to thank Robert Bluth of the Naval Postgraduate School and Jesse Barge and Dan Bierly of Zivko Aeronautics.

  2. Optimizing an undulating magnetic microswimmer for cargo towing.

    PubMed

    Gutman, Emiliya; Or, Yizhar

    2016-06-01

    One of the promising capabilities of magnetic microswimmers is towing a cargo, which can be used for targeted drug delivery or performing tissue biopsy. A key question is what should be the optimal size ratio between the cargo and the swimmer's flexible tail. This question is addressed here for the simplest theoretical model of a magnetic microswimmer undergoing planar undulations-a spherical load connected by a torsion spring to a rigid slender link. The swimmer's dynamic is formulated and leading-order expressions for its motion are obtained explicitly under small-amplitude approximation. Optimal combinations of magnetic actuation frequency, torsion stiffness, and tail length for maximizing displacement, average speed, or energetic efficiency are obtained. The theoretical results are compared with reported experiments in several types of cargo-towing magnetic microswimmers.

  3. Optimizing an undulating magnetic microswimmer for cargo towing

    NASA Astrophysics Data System (ADS)

    Gutman, Emiliya; Or, Yizhar

    2016-06-01

    One of the promising capabilities of magnetic microswimmers is towing a cargo, which can be used for targeted drug delivery or performing tissue biopsy. A key question is what should be the optimal size ratio between the cargo and the swimmer's flexible tail. This question is addressed here for the simplest theoretical model of a magnetic microswimmer undergoing planar undulations—a spherical load connected by a torsion spring to a rigid slender link. The swimmer's dynamic is formulated and leading-order expressions for its motion are obtained explicitly under small-amplitude approximation. Optimal combinations of magnetic actuation frequency, torsion stiffness, and tail length for maximizing displacement, average speed, or energetic efficiency are obtained. The theoretical results are compared with reported experiments in several types of cargo-towing magnetic microswimmers.

  4. A space tethered towing method using tension and platform thrusts

    NASA Astrophysics Data System (ADS)

    Meng, Zhongjie; Wang, Bingheng; Huang, Panfeng

    2017-01-01

    Orbit maneuver via tether is a promising countermeasure for space debris removal and satellite orbit transfer. A space tethered towing method is explored that utilizes thrust to fulfill transfer and bounded tension to stabilize tether heading. For this purpose, a time-energy optimal orbit is designed by Gauss pseudospectral method. The theoretical attitude commands are obtained by equilibria analysis. An effective attitude control strategy is presented where the commands are optimized first and then feedback controller is designed. To deal with the underactuated problem with tension constraint, hierarchical sliding mode theory is employed and an adaptive anti-windup module is added to mitigate the actuator saturation. Simulation results show that the target is towed effectively by the thrusts, and a smooth tracking for the commands of tether length and in-plane tether heading is guaranteed by the bounded tension. In addition, the designed controller also presents appreciable robustness to model error and determination error.

  5. Fractional-step Tow-Thomas biquad filters

    NASA Astrophysics Data System (ADS)

    Freeborn, Todd J.; Maundy, Brent; Elwakil, Ahmed

    In this paper we propose the use of fractional capacitors in the Tow-Thomas biquad to realize both fractional lowpass and asymmetric bandpass filters of order 0<α1+α2≤2, where α1 and α2 are the orders of the fractional capacitors and 0<α1,2≤1. We show how these filters can be designed using an integer-order transfer function approximation of the fractional capacitors. MATLAB and PSPICE simulations of first order fractional-step low and bandpass filters of order 1.1, 1.5, and 1.9 are given as examples. Experimental results of fractional low pass filters of order 1.5 implemented with silicon-fabricated fractional capacitors verify the operation of the fractional Tow-Thomas biquad.

  6. An Optically Pumped Magnetometer Working in the Light-Shift Dispersed Mz Mode

    PubMed Central

    Schultze, Volkmar; Schillig, Bastian; IJsselsteijn, Rob; Scholtes, Theo; Woetzel, Stefan; Stolz, Ronny

    2017-01-01

    We present an optically pumped magnetometer working in a new operational mode—the light-shift dispersed Mz (LSD-Mz) mode. It is realized combining various features; (1) high power off-resonant optical pumping; (2) Mz configuration, where pumping light and magnetic field of interest are oriented parallel to each other; (3) use of small alkali metal vapor cells of identical properties in integrated array structures, where two such cells are pumped by circularly polarized light of opposite helicity; and (4) subtraction of the Mz signals of these two cells. The LSD-Mz magnetometer’s performance depends on the inherent and very complex interplay of input parameters. In order to find the configuration of optimal magnetometer resolution, a sensitivity analysis of the input parameters by means of Latin Hypercube Sampling was carried out. The resulting datasets of the multi-dimensional parameter space exploration were assessed by a subsequent physically reasonable interpretation. Finally, the best shot-noise limited magnetic field resolution was determined within that parameter space. As the result, using two 50 mm3 integrated vapor cells a magnetic field resolution below 10 fT/√Hz at Earth’s magnetic field strength is possible. PMID:28287414

  7. Remote sensing of the plasmasphere mass density using ground magnetometers and the FLIP model

    NASA Astrophysics Data System (ADS)

    Zesta, Eftyhia; Chi, Peter; Moldwin, Mark; Jorgensen, Anders; Richards, Phil; Boudouridis, Athanasios; Duffy, Jared

    2012-07-01

    The SAMBA (South American Meridional B-field Array) chain is a Southern Hemisphere meridional chain of 12 magnetometers, 11 of them at L=1.1 to L=2.5 along the coast of Chile and in the Antarctica peninsula, and one auroral station along the same meridian. SAMBA is ideal for low and mid-latitude studies of geophysical events and ULF waves. The MEASURE (Magnetometers along the Eastern Atlantic Seaboard for Undergraduate Research and Education) and McMAC (Mid-continent Magnetoseismic Chain) chains are Northern Hemisphere meridional chains in the same local time as SAMBA, but cover low to sub-auroral latitudes. SAMBA is partly conjugate to MEASURE and McMAC chains, offering unique opportunities for inter-hemispheric studies. We use 5 of the SAMBA stations and an even larger number of conjugate stations from the Northern hemisphere to determine the field line resonance (FLR) frequency of closely spaced flux tubes in the inner magnetosphere. Standard inversion techniques are used to derive the equatorial mass density of these flux tubes from the FLRs. We thus yield the mass density distribution of the plasmasphere for specific events and compare our results with results from the FLIP thermosphere-ionosphere model model. We find that for moderate activity the model determined FLR radial distribution is in excellent agreement with the observed distribution. During storm time observations indicate stronger depletion than predicted by the model initial runs.

  8. Versatile magnetometer assembly for characterizing magnetic properties of nanoparticles

    NASA Astrophysics Data System (ADS)

    Araujo, J. F. D. F.; Bruno, A. C.; Louro, S. R. W.

    2015-10-01

    We constructed a versatile magnetometer assembly for characterizing iron oxide nanoparticles. The magnetometer can be operated at room temperature or inside a cryocooler at temperatures as low as 6 K. The magnetometer's sensor can be easily exchanged and different detection electronics can be used. We tested the assembly with a non-cryogenic commercial Hall sensor and a benchtop multimeter in a four-wire resistance measurement scheme. A magnetic moment sensitivity of 8.5 × 10-8 Am2 was obtained with this configuration. To illustrate the capability of the assembly, we synthesized iron oxide nanoparticles coated with different amounts of a triblock copolymer, Pluronic F-127, and characterized their magnetic properties. We determined that the polymer coating does not affect the magnetization of the particles at room temperature and demonstrates that it is possible to estimate the average size of coating layers from measurements of the magnetic field of the sample.

  9. Assessing and ensuring GOES-R magnetometer accuracy

    NASA Astrophysics Data System (ADS)

    Carter, Delano; Todirita, Monica; Kronenwetter, Jeffrey; Dahya, Melissa; Chu, Donald

    2016-05-01

    The GOES-R magnetometer subsystem accuracy requirement is 1.7 nanoteslas (nT). During quiet times (100 nT), accuracy is defined as absolute mean plus 3 sigma error per axis. During storms (300 nT), accuracy is defined as absolute mean plus 2 sigma error per axis. Error comes both from outside the magnetometers, e.g. spacecraft fields and misalignments, as well as inside, e.g. zero offset and scale factor errors. Because zero offset and scale factor drift over time, it will be necessary to perform annual calibration maneuvers. To predict performance before launch, we have used Monte Carlo simulations and covariance analysis. With the proposed calibration regimen, both suggest that the magnetometer subsystem will meet its accuracy requirements.

  10. Spin-Damping in an RF atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Alem, Orang; Romalis, Michael V.; Sauer, Karen L.

    2009-05-01

    Optically pumped atomic magnetometers have demonstrated an improved sensitivity over standard tuned coils for frequencies less than 50 MHz, making these radio-frequency (RF) magnetometers attractive for low-field NMR (for example, Budker and Romalis, Nature Physics 3, April 2007). Such magnetometers are often plagued by transient effects resulting in decreased sensitivity. The decay time of these transients, or ringing, can last for milliseconds, which is particularly detrimental for rapidly decaying NMR signals. We have found that actively damping the ringing of the atomic spins can significantly reduce such dead time. This spin-damping of the atomic transients is achieved through a negative feedback mechanism in which part of the optical signal during ringing is used to apply an RF field forcing the realignment of the atomic spins with the static magnetic field. We have successfully implemented spin-damping in 100 μs and recovered our femto-Tesla signal previously obscured by the ringing.

  11. Rotating sample magnetometer for cryogenic temperatures and high magnetic fields.

    PubMed

    Eisterer, M; Hengstberger, F; Voutsinas, C S; Hörhager, N; Sorta, S; Hecher, J; Weber, H W

    2011-06-01

    We report on the design and implementation of a rotating sample magnetometer (RSM) operating in the variable temperature insert (VTI) of a cryostat equipped with a high-field magnet. The limited space and the cryogenic temperatures impose the most critical design parameters: the small bore size of the magnet requires a very compact pick-up coil system and the low temperatures demand a very careful design of the bearings. Despite these difficulties the RSM achieves excellent resolution at high magnetic field sweep rates, exceeding that of a typical vibrating sample magnetometer by about a factor of ten. In addition the gas-flow cryostat and the high-field superconducting magnet provide a temperature and magnetic field range unprecedented for this type of magnetometer.

  12. Versatile magnetometer assembly for characterizing magnetic properties of nanoparticles.

    PubMed

    Araujo, J F D F; Bruno, A C; Louro, S R W

    2015-10-01

    We constructed a versatile magnetometer assembly for characterizing iron oxide nanoparticles. The magnetometer can be operated at room temperature or inside a cryocooler at temperatures as low as 6 K. The magnetometer's sensor can be easily exchanged and different detection electronics can be used. We tested the assembly with a non-cryogenic commercial Hall sensor and a benchtop multimeter in a four-wire resistance measurement scheme. A magnetic moment sensitivity of 8.5 × 10(-8) Am(2) was obtained with this configuration. To illustrate the capability of the assembly, we synthesized iron oxide nanoparticles coated with different amounts of a triblock copolymer, Pluronic F-127, and characterized their magnetic properties. We determined that the polymer coating does not affect the magnetization of the particles at room temperature and demonstrates that it is possible to estimate the average size of coating layers from measurements of the magnetic field of the sample.

  13. Design and Analyses of a MEMS Based Resonant Magnetometer.

    PubMed

    Ren, Dahai; Wu, Lingqi; Yan, Meizhi; Cui, Mingyang; You, Zheng; Hu, Muzhi

    2009-01-01

    A novel design of a MEMS torsional resonant magnetometer based on Lorentz force is presented and fabricated. The magnetometer consists of a silicon resonator, torsional beam, excitation coil, capacitance plates and glass substrate. Working in a resonant condition, the sensor's vibration amplitude is converted into the sensing capacitance change, which reflects the outside magnetic flux-density. Based on the simulation, the key structure parameters are optimized and the air damping effect is estimated. The test results of the prototype are in accordance with the simulation results of the designed model. The resolution of the magnetometer can reach 30 nT. The test results indicate its sensitivity of more than 400 mV/μT when operating in a 10 Pa vacuum environment.

  14. Assessing and Ensuring GOES-R Magnetometer Accuracy

    NASA Technical Reports Server (NTRS)

    Carter, Delano R.; Todirita, Monica; Kronenwetter, Jeffrey; Chu, Donald

    2016-01-01

    The GOES-R magnetometer subsystem accuracy requirement is 1.7 nanoteslas (nT). During quiet times (100 nT), accuracy is defined as absolute mean plus 3 sigma. During storms (300 nT), accuracy is defined as absolute mean plus 2 sigma. Error comes both from outside the magnetometers, e.g. spacecraft fields and misalignments, as well as inside, e.g. zero offset and scale factor errors. Because zero offset and scale factor drift over time, it will be necessary to perform annual calibration maneuvers. To predict performance before launch, we have used Monte Carlo simulations and covariance analysis. Both behave as expected, and their accuracy predictions agree within 30%. With the proposed calibration regimen, both suggest that the GOES-R magnetometer subsystem will meet its accuracy requirements.

  15. NQR detection of explosive simulants using RF atomic magnetometers

    NASA Astrophysics Data System (ADS)

    Monti, Mark C.; Alexson, Dimitri A.; Okamitsu, Jeffrey K.

    2016-05-01

    Nuclear Quadrupole Resonance (NQR) is a highly selective spectroscopic method that can be used to detect and identify a number of chemicals of interest to the defense, national security, and law enforcement community. In the past, there have been several documented attempts to utilize NQR to detect nitrogen bearing explosives using induction sensors to detect the NQR RF signatures. We present here our work on the NQR detection of explosive simulants using optically pumped RF atomic magnetometers. RF atomic magnetometers can provide an order of magnitude (or more) improvement in sensitivity versus induction sensors and can enable mitigation of RF interference, which has classically has been a problem for conventional NQR using induction sensors. We present the theory of operation of optically pumped RF atomic magnetometers along with the result of laboratory work on the detection of explosive simulant material. An outline of ongoing work will also be presented along with a path for a fieldable detection system.

  16. Participation in the Cluster Magnetometer Consortium for the Cluster Mission

    NASA Technical Reports Server (NTRS)

    Kivelson, Margaret

    1997-01-01

    Prof. M. G. Kivelson (UCLA) and Dr. R. C. Elphic (LANL) are Co-investigators on the Cluster Magnetometer Consortium (CMC) that provided the fluxgate magnetometers and associated mission support for the Cluster Mission. The CMC designated UCLA as the site with primary responsibility for the inter-calibration of data from the four spacecraft and the production of fully corrected data critical to achieving the mission objectives. UCLA was also charged with distributing magnetometer data to the U.S. Co-investigators. UCLA also supported the Technical Management Team, which was responsible for the detailed design of the instrument and its interface. In this final progress report we detail the progress made by the UCLA team in achieving the mission objectives.

  17. Optimizing an undulating magnetic microswimmer for cargo towing

    NASA Astrophysics Data System (ADS)

    Or, Yizhar; Gutman, Emiliya

    2015-11-01

    One of the promising applications of robotic microswimmers is towing a cargo for controlled drug delivery, micro-surgery or tumor detection. This capability has been demonstrated by the magnetically-actuated microswimmer of Dreyfus et al. [Nature 2005] in which a red blood cell was attached to a chain of magnetic beads connected by flexible DNA links. A key question is what should be the optimal size of the magnetic tail for towing a given cargo. This question is addressed here for the simplest theoretical model of a magnetic microswimmer under planar undulations - a spherical load connected by a torsion spring to a magnetized rigid slender link. The swimmer's dynamics is formulated assuming negligible hydrodynamic interaction and leading-order expressions for the resulting motion are obtained explicitly under small amplitude approximation. Optimal combinations of magnetic actuation frequency, torsion stiffness, and tail length for maximizing displacement or average speed are obtained. The theoretical results are compared with several reported magnetic microswimmers, and also agree qualitatively with recent results on cargo towing by screw rotation of magnetic helical tails [Walker et al., ACS Nano Letters 2015]. This work is supported by the Israeli Science Foundation (ISF) under Grant No. 567/14.

  18. M2-F1 in hangar with Pontiac tow vehicle

    NASA Technical Reports Server (NTRS)

    1963-01-01

    The M2-F1 Lifting Body is seen here in a hangar with its hotrod Pontiac convertible tow vehicle at the Flight Research Center (later the Dryden Flight Research Center), Edwards, California. The car was a 1963 Pontiac Catalina convertible, fitted with a 421-cubic-inch tripower engine like those being run at the Daytona 500 auto race. The vehicle also had a four-speed transmission and a heavy-duty suspension and cooling system. A roll bar was also added and the passenger seat turned around so an observer could watch the M2-F1 while it was being towed. The rear seat was removed and a second, side-facing seat installed. The lifting-body team used the Pontiac for all the ground-tow flights over the next three years. The wingless, lifting body aircraft design was initially conceived as a means of landing an aircraft horizontally after atmospheric reentry. The absence of wings would make the extreme heat of re-entry less damaging to the vehicle. In 1962, Dryden management approved a program to build a lightweight, unpowered lifting body as a prototype to flight test the wingless concept. It would look like a 'flying bathtub,' and was designated the M2-F1, the 'M' referring to 'manned' and 'F' referring to 'flight' version. It featured a plywood shell placed over a tubular steel frame crafted at Dryden. Construction was completed in 1963. The first flight tests of the M2-F1 were over Rogers Dry Lake at the end of a tow rope attached to a hopped-up Pontiac convertible driven at speeds up to about 120 mph. This vehicle needed to be able to tow the M2-F1 on the Rogers Dry Lakebed adjacent to NASA's Flight Research Center (FRC) at a minimum speed of 100 miles per hour. To do that, it had to handle the 400-pound pull of the M2-F1. Walter 'Whitey' Whiteside, who was a retired Air Force maintenance officer working in the FRC's Flight Operations Division, was a dirt-bike rider and hot-rodder. Together with Boyden 'Bud' Bearce in the Procurement and Supply Branch of the FRC, Whitey

  19. Surface Towed CSEM Systems for Shallow Water Mapping

    NASA Astrophysics Data System (ADS)

    Sherman, J.; Constable, S.; Kannberg, P. K.

    2015-12-01

    We have developed a low-power, surface towed electric dipole-dipole system suitable for mapping seafloor geology in shallow water and deployable from small boats. The transmitter is capable of up to 50 amps output using 12 VDC from a 110/240 VAC power supply, and can generate an arbitrary GPS stabilized ternary waveform. Transmitter antennas are typically 50 to 100 m long. Receivers are built around the standard Scripps seafloor electrode, amplifier, and logging systems but housed in floating PVC cases and equipped with GPS timing and positioning, pitch/roll/heading sensors, and accelerometers. Receiver dipoles are 1.5 m long rigid booms held 1 m below the surface. As with the Scripps deep-towed Vulcan system, rigid antennas are used to avoid noise associated with flexible antennas moving across Earth's magnetic field. The tow cable is a simple floating rope up to 1000 m long. Water depth and conductivity are sampled continuously in order to provide constraints for apparent resistivity calculations and inversion, and moored seafloor recorders can be used to extend transmitter/receiver offsets. The entire system can be air freighted and transported in one utility vehicle. We will present results from a study to map permafrost in shallow water off Prudhoe Bay, Alaska.

  20. Evaluation of a Highly Anticlastic Panel with Tow Overlaps

    NASA Technical Reports Server (NTRS)

    Wu, K. Chauncey; Gurdal, Zafer

    2007-01-01

    A rectangular, variable-stiffness panel with tow overlaps was manufactured using an advanced tow placement machine. The cured panel had large anticlastic imperfections, with measured amplitudes of over two times the average panel thickness. These imperfections were not due to the overall steered-fiber layup or the tow overlaps, but instead resulted from local asymmetries in the laminate that were caused by a manufacturing oversight. In the nominal panel layup, fiber angles vary linearly from 60 degrees on the panel axial centerline to 30 degrees on the parallel edges. A geometrically nonlinear analysis was performed with a -280 degree Fahrenheit thermal load to simulate the postcure cooldown to room temperature. The predicted geometric imperfections correlated well with the measured panel shape. Unique structural test fixtures were then developed which greatly reduced these imperfections, but they also caused prestresses in the panel. Surface imperfections measured after the panel was installed in the test fixtures were used with nonlinear finite element analyses to predict these fixturing-induced prestresses. These prestresses were also included in structural analyses of panel end compression to failure, and the analytical results compared well with test data when both geometric and material nonlinearities were included.

  1. Man-Portable Simultaneous Magnetometer and Electromagnetic System

    DTIC Science & Technology

    2009-08-01

    RTK GPS receiver on backpack (on top of EM61 electronics box), and boom and 3rd wheel hosting magnetometer 4’ in front of EM61 coil. GPS antenna and...Interleaving (MPI) box that acquires magnetometer data between EM61 pulses • An RTK GPS • Custom software running on the Allegro that acquires...EM61 Sampling Rate COTS 75 Hz pulse repetition rate (10 Hz serial output) GPS Trimble RTK with 1PPS output. 10Hz GGK output. GPS antenna halfway

  2. A low-power, high-sensitivity micromachined optical magnetometer

    NASA Astrophysics Data System (ADS)

    Mhaskar, R.; Knappe, S.; Kitching, J.

    2012-12-01

    We demonstrate an optical magnetometer based on a microfabricated 87Rb vapor cell in a micromachined silicon sensor head. The alkali atom density in the vapor cell is increased by heating the cell with light brought to the sensor through an optical fiber, and absorbed by colored filters attached to the cell windows. A second fiber-optically coupled beam optically pumps and interrogates the atoms. The magnetometer operates on 140 mW of heating power and achieves a sensitivity below 20 fT/√Hz throughout most of the frequency band from 15 Hz to 100 Hz. Such a sensor can measure magnetic fields from the human heart and brain.

  3. Three-axis atomic magnetometer based on spin precession modulation

    SciTech Connect

    Huang, H. C.; Dong, H. F. Hu, X. Y.; Chen, L.; Gao, Y.

    2015-11-02

    We demonstrate a three-axis atomic magnetometer with one intensity-modulated pump beam and one orthogonal probe beam. The main field component is measured using the resonance of the pumping light, while the transverse field components are measured simultaneously using the optical rotation of the probe beam modulated by the spin precession. It is an all-optical magnetometer without using any modulation field or radio frequency field. Magnetic field sensitivity of 0.8 pT/Hz{sup 1∕2} is achieved under a bias field of 2 μT.

  4. Lunar physical properties from analysis of magnetometer data

    NASA Technical Reports Server (NTRS)

    Daily, W. D.

    1979-01-01

    The electromagnetic properties of the lunar interior are discussed with emphasis on (1) bulk, crustal, and local anomalous conductivity; (2) bulk magnetic permeability measurements, iron abundance estimates, and core size limits; (3) lunar ionosphere and atmosphere; and (4) crustal magnetic remanence: scale size measurements and constraints on remanence origin. Appendices treat the phase relationship between the energetic particle flux modulation and current disc penetrations in the Jovian magnetosphere (Pioneer 10 inbound) theories for the origin of lunar magnetism; electrical conductivity anomalies associated with circular lunar maria; electromagnetic properties of the Moon; Mare Serenitatis conductivity anomaly detected by Apollo 16 and Lunokhod 2 magnetometers; and lunar properties from magnetometer data: effects of data errors.

  5. A high-sensitivity push-pull magnetometer

    SciTech Connect

    Breschi, E.; Grujić, Z. D.; Knowles, P.; Weis, A.

    2014-01-13

    We describe our approach to atomic magnetometry based on the push-pull optical pumping technique. Cesium vapor is pumped and probed by a resonant laser beam whose circular polarization is modulated synchronously with the spin evolution dynamics induced by a static magnetic field. The magnetometer is operated in a phase-locked loop, and it has an intrinsic sensitivity below 20fT/√(Hz), using a room temperature paraffin-coated cell. We use the magnetometer to monitor magnetic field fluctuations with a sensitivity of 300fT/√(Hz)

  6. Remote Sensing of Equatorial Mass Density via Virtual Ground-Based Magnetometers in the SWMF Global Magnetospheric Model

    NASA Astrophysics Data System (ADS)

    Ellington, S.; Moldwin, M.

    2015-12-01

    The resonant frequencies of standing Alfven waves (field line resonances, or FLRs) depend on the equatorial mass density distribution. We can identify field line resonances using cross-phase spectra and power spectral densities, and the equatorial mass density distribution can be extracted from the frequency assuming an axisymmetric and power law distribution along dipolar field lines. Here we report the use of arrays of virtual ground-based magnetometers in two simulations ran in the SWMF global magnetospheric model to remotely sense equatorial mass density. First we confirm that SWMF reproduces a multi-harmonic distribution of FLRs in the dayside magnetospheric cavity, and then we determine the time-dependent resonant frequency from an analysis of the short-time power spectral density and cross-phase spectra of the magnetic vector fields from meridianal chains of virtual ground-based magnetometers. We show that this technique can accurately measure the spatiotemporal evolution of mass density within the simulations by comparing the FLR inferred densities with the in situ data. This is the first such attempt at using virtual ground-based magnetometers in a self-consistent, three-dimensional, coupled global magnetospheric and ionospheric model to remote sense the equatorial mass density.

  7. Early Results from the IMI-30 Towed Sonar System

    NASA Astrophysics Data System (ADS)

    Edwards, M. H.; Rognstad, M. R.; Tottori, S. N.; Davis, R. B.; Appelgate, T. B.; Johnson, P. D.; Kevis-Stirling, A.

    2006-12-01

    The Hawaii Mapping Research Group (HMRG) of the University of Hawaii has designed and built a 30 kHz deep-towed sonar, the IMI-30, which simultaneously collects interferometric bathymetry and backscatter data. The sonar is capable of being deployed to 6000 m water depth, where it is towed 100-500 m above the seafloor yielding a total swath width of 1-5 km for sidescan and somewhat less than that for bathymetry. The across-track resolution is <10 m for bathymetry depending on towing geometry and substrate type, and 0.3- 3 m for sidescan, depending on the selected transmit pulse length and tow vehicle altitude. The along-track resolution, which is dependent on vehicle speed and pulse repetition rate, varies between 0.6 and 3 meters. Here we report on data collected by the system during two different deployments in the Pacific: the IMI-30's initial field program in the Lau Basin in 2004 and the most recent survey using the system, south of Oahu in June of 2006. Between the 2004 Lau program and the June 2006 survey, several engineering improvements were made including: 1) changing the housings of the side-looking transducers from cast polyurethane to oil- filled polyethylene; 2) adding syntactic foam baffling to reduce surface bounce; 3) synchronizing sound velocimeter measurements with sonar transmit; 4) adding sub-bottom transducers and associated electronics to the tow vehicle; 5) adding two additional side-looking transducer rows per side, and 6) upgrading the surface and subsurface power supplies. This engineering effort has improved reliability of the system by eliminating transducer failures caused by seawater leakage and power supply over-temperature shutdown in tropical waters. Reducing the system noise - electrical, hydrodynamic, and acoustic - has improved data quality and extended the swath width. The addition of sub-bottom data acquisition further increases the utility of the IMI-30 system. Our presentation will document the engineering effort and

  8. Full Scale Tunnel (FST) and Seaplane Tow Channel

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Installation of Careystone covering at the Full-Scale Tunnel (FST) facility. The corrugated concrete and asbestos panels (1/4 inch thick; 42 inches wide; 62 inches long) which were used as siding and roofing for the Full-Scale Tunnel were manufactured by The Philip Carey Company. For the NACA, the choice of Careystone had been based on several factors. First and foremost was its low cost. NACA engineers had observed the very durable, low-maintenance and fireproof qualities of the concrete-asbestos covering of the airship hanger at Langley Field. Further, tests showed the material to be 3.8 times stronger than required (The maximum load the material was expected to withstand was 52 lbs. per square foot; the breaking load was 196 lbs. per sq. ft.). L4695 shows the interior view of construction of the Tow Tank. In the late 1920s, the NACA decided to investigate the aero/hydro dynamics of floats for seaplanes. A Hydrodynamics Branch was established in 1929 and special towing basin was authorized in March of that same year. Starr Truscott (the first head of the new division) described the tank in NACA TR 470: 'The N.A.C.A. tank is of the Froude type; that is, the model which is being tested is towed through still water at successive constant speeds from a carriage spanning the tank. At each constant speed the towing pull is measured, the trim and the rise, or change of draft, are recorded and, if the model is being towed at a fixed trim, the moment required to hold it there is measured and recorded.' 'The reinforced concrete basin containing the water has the following dimensions: (1) Length on water, extreme, 2,020 feet; (2) Normal width of water surface, 24 feet; (3) Normal depth of water, 12 feet; (4) Length of 12 foot depth, 1,980 feet.' This picture shows the tank before the coving was added. This brought the rails for the carriage closer together and helped suppress waves produced by the models. The finished tank would be filled with approximately 4 million

  9. Method and apparatus for deregistering multi-filament tow and product thereof

    DOEpatents

    Lukhard, Craig R.; Potter, Jerry F.; Todd, Maurice C.

    1995-01-01

    A method and apparatus for deregistering drawn crimped nylon multifilament tow includes the steps of stretching the tow under constant controlled tension at a temperature below the glass transition temperature of the nylon. The apparatus includes means for sensing the tension of the tow between the feed and draw sections of a stretching device and producing a signal representative of the tension sensed and a controller for changing the speed of the draw section actuated by said signal.

  10. The Status of Infantry TOW, LAW, and Dragon Training in USAREUR.

    DTIC Science & Technology

    1977-11-01

    and 100% of squad leaders. On any given day, an estimated one-third of personnel were unavailable for train- ing. Some CONUS-trained TOW gunners were...not assigned to TOW squads . LAW On any given day, an estimated 20% were unavailable for training. Dragon No personnel problems were apparent. Gunners...amount of gunner and squad training. Most gunners received intensive training only in preparation for annual live firing. Most TOW squads had no

  11. Magnetic induction measurements using an all-optical {sup 87}Rb atomic magnetometer

    SciTech Connect

    Wickenbrock, Arne; Tricot, François; Renzoni, Ferruccio

    2013-12-09

    In this work we propose, and experimentally demonstrate, the use of a self-oscillating all-optical atomic magnetometer for magnetic induction measurements. Given the potential for miniaturization of atomic magnetometers, and their extreme sensitivity, the present work shows that atomic magnetometers may play a key role in the development of instrumentation for magnetic induction tomography.

  12. Induction magnetometer using a high-Tc superconductor coil

    NASA Astrophysics Data System (ADS)

    Sasada, Ichiro

    2010-05-01

    An induction magnetometer consisting of a search coil and an inverting operational amplifier is simple in structure and in signal transferring mechanism from the magnetic field input to the voltage output. Because this magnetometer is based on Faraday's law of induction, it has a lower cutoff frequency r/(2πL), where r is the resistance of the coil and L is its inductance. An attempt has been made to lower the cutoff frequency of the induction magnetometer by using a high-Tc superconductor coil. With a pancake coil (inner diameter ≈18 cm and outer diameter ≈23 cm, 92 turns, 3.23 mH) made of a Bismuth strontium calcium copper oxide (BSCCO) superconductor tape of 5 mm in width and 0.23 mm in thickness, the cutoff frequency achieved was 1.7 Hz which is much lower than that obtained with a bulky copper search coil which is typically in the range of 10-20 Hz. In the experiment, an inverting amplifier was made with a complementary metal-oxide semiconductor operational amplifier and was immersed in liquid nitrogen together with a BSCCO high-Tc superconducting coil. Discussion is made on the resolution of the induction magnetometer using a high-Tc superconductor search coil.

  13. Astronaut Alan Bean deploys Lunar Surface Magnetometer on lunar surface

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot, deploys the Lunar Surface Magnetometer (LSM) during the first Apollo 12 extravehicular activity on the Moon. The LSM is a component of the Apollo Lunar Surface Experiments Package (ALSEP). The Lunar Module can be seen in the left background.

  14. A new algorithm for attitude-independent magnetometer calibration

    NASA Technical Reports Server (NTRS)

    Alonso, Roberto; Shuster, Malcolm D.

    1994-01-01

    A new algorithm is developed for inflight magnetometer bias determination without knowledge of the attitude. This algorithm combines the fast convergence of a heuristic algorithm currently in use with the correct treatment of the statistics and without discarding data. The algorithm performance is examined using simulated data and compared with previous algorithms.

  15. Real-Time Attitude Independent Three Axis Magnetometer Calibration

    NASA Technical Reports Server (NTRS)

    Crassidis, John L.; Lai, Kok-Lam; Harman, Richard R.

    2003-01-01

    In this paper new real-time approaches for three-axis magnetometer sensor calibration are derived. These approaches rely on a conversion of the magnetometer-body and geomagnetic-reference vectors into an attitude independent observation by using scalar checking. The goal of the full calibration problem involves the determination of the magnetometer bias vector, scale factors and non-orthogonality corrections. Although the actual solution to this full calibration problem involves the minimization of a quartic loss function, the problem can be converted into a quadratic loss function by a centering approximation. This leads to a simple batch linear least squares solution. In this paper we develop alternative real-time algorithms based on both the extended Kalman filter and Unscented filter. With these real-time algorithms, a full magnetometer calibration can now be performed on-orbit during typical spacecraft mission-mode operations. Simulation results indicate that both algorithms provide accurate integer resolution in real time, but the Unscented filter is more robust to large initial condition errors than the extended Kalman filter. The algorithms are also tested using actual data from the Transition Region and Coronal Explorer (TRACE).

  16. Magnetometer Based on the Opto-Electronic Oscillator

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey B.; Strekalov, Dmitry; Maleki, Lute

    2005-01-01

    We theoretically propose and discuss properties of two schemes of an all-optical self-oscillating magnetometer based on an opto-electronic oscillator stabilized with an atomic vapor cell. Proof of the principle DC magnetic field measurements characterized with 2 x 10(exp -7) G sensitivity and 1 - 1000 mG dynamic range in one of the schemes are demonstrated.

  17. Position-Finding Instrument Built Around a Magnetometer

    NASA Technical Reports Server (NTRS)

    Ketchum, Eleanor

    2004-01-01

    A coarse-positioning instrument is built around a three-axis magnetometer. The magnetometer is of a type that is made of inexpensive hardware and is suitable for use aboard spacecraft orbiting no more than 1,000 km above the surface of the Earth. A data processor programmed with suitable software and equipped with a central processing unit, random-access memory, programmable read-only memory, and interface circuitry for communication with external equipment are added to the basic magnetometer to convert it into a coarse-positioning instrument. Although the instrument was conceived for use aboard spacecraft, it could be useful for navigation on Earth under some circumstances. A major feature of the proposed instrument is an ability to generate a coarse estimate of its position in real time (that is, without start-up delay). Algorithms needed to solve the position equations have been developed. These include algorithms to work around gaps in measurement data that arise from a singularity near the minimum in the magnetic field of the Earth. Some work has been done to develop a prototype of this instrument incorporating a standard three-axis flux-gate magnetometer and a Pentium P-5 (or equivalent) processor with a clock frequency of 120 MHz. Alternatively, the processor could be of the 486 class. A computer model of the instrument has been completed and tested.

  18. Small Fluxgate Magnetometers: Development and Future Trends in Spain

    PubMed Central

    Ciudad, David; Díaz-Michelena, Marina; Pérez, Lucas; Aroca, Claudio

    2010-01-01

    In this paper, we give an overview of the research on fluxgate magnetometers carried out in Spain. In particular we focus in the development of the planar-type instruments. We summarize the fabrication processes and signal processing developments as well as their use in complex systems and space. PMID:22294904

  19. Small fluxgate magnetometers: development and future trends in Spain.

    PubMed

    Ciudad, David; Díaz-Michelena, Marina; Pérez, Lucas; Aroca, Claudio

    2010-01-01

    In this paper, we give an overview of the research on fluxgate magnetometers carried out in Spain. In particular we focus in the development of the planar-type instruments. We summarize the fabrication processes and signal processing developments as well as their use in complex systems and space.

  20. Beacon Position and Attitude Navigation Aided by a Magnetometer

    DTIC Science & Technology

    2010-06-01

    i · B . (12) When the scale and shift influences of the analog circuitry are considered, the actual measurement of the magnetometer is M = s...1350–1351. 22. Carta , D. G.; Lackowski, D. H. Estimation of Orthogonal Transformations in Strapdown Inertial Systems. IEEE Transactions on

  1. Engineered Polymer Composites Through Electrospun Nanofiber Coating of Fiber Tows

    NASA Technical Reports Server (NTRS)

    Kohlman, Lee W.; Bakis, Charles; Williams, Tiffany S.; Johnston, James C.; Kuczmarski, Maria A.; Roberts, Gary D.

    2014-01-01

    Composite materials offer significant weight savings in many aerospace applications. The toughness of the interface of fibers crossing at different angles often determines failure of composite components. A method for toughening the interface in fabric and filament wound components using directly electrospun thermoplastic nanofiber on carbon fiber tow is presented. The method was first demonstrated with limited trials, and then was scaled up to a continuous lab scale process. Filament wound tubes were fabricated and tested using unmodified baseline towpreg material and nanofiber coated towpreg.

  2. 49 CFR 393.71 - Coupling devices and towing methods, driveaway-towaway operations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... means of transmitting forces between the vehicles shall not be used to tow a motor vehicle weighing more... means of a saddle-mount shall have the motion of the front wheels restrained if under any condition of... constructed as to freely permit motion in both horizontal and vertical planes between the towed and...

  3. 49 CFR 393.71 - Coupling devices and towing methods, driveaway-towaway operations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... bumpers as a means of transmitting forces between the vehicles shall not be used to tow a motor vehicle... towed by means of a saddle-mount shall have the motion of the front wheels restrained if under any... shall be so constructed as to freely permit motion in both horizontal and vertical planes between...

  4. 46 CFR 27.203 - What are the requirements for fire detection on towing vessels?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false What are the requirements for fire detection on towing... detection on towing vessels? You must have a fire-detection system installed on your vessel to detect engine... use an existing engine-room-monitoring system (with fire-detection capability) instead of a...

  5. 46 CFR 27.203 - What are the requirements for fire detection on towing vessels?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false What are the requirements for fire detection on towing... detection on towing vessels? You must have a fire-detection system installed on your vessel to detect engine... use an existing engine-room-monitoring system (with fire-detection capability) instead of a...

  6. Influence of the vertical load exerted by the trailer on the coupling device on towing vehicle's steerability and stability

    NASA Astrophysics Data System (ADS)

    Więckowski, D.; Pusty, T.; Jędrys, P.

    2016-09-01

    The paper concerns an analysis of the steerability and stability of a motor vehicle towing a trailer during the double lane change manoeuvre. As results of experimental road tests carried out on an airfield runway, time histories of the following parameters were determined: steering angle, lateral acceleration, and drift angle of the towing vehicle, as well as angular velocity of towing vehicle yaw. The tests were performed for various states of the vertical load exerted on towing vehicle's coupling device.

  7. A tow concept for the space shuttle orbiter approach and landing test

    NASA Technical Reports Server (NTRS)

    Bonner, T. F., Jr.; Pride, J. D., Jr.

    1976-01-01

    The tow concept provides the means for evaluating the orbiter aerodynamic performance and handling qualities in the same configuration as expected in actual space shuttle flight operation. A Boeing 747-100 aircraft has engine-out capability to tow the orbiter to an altitude that permits a safe orbiter approach and landing. The tow concept also provides a means for conducting a comprehensive ground test program before proceeding into the actual ALT flight operations. The implementation of the tow concept requires only a minor structural modification in the nose section of the orbiter vehicle; requires minor modifications in the 747 cargo bay; and makes use of those orbiter onboard systems installed in the ALT orbiter vehicle. The 747 wake turbulence does not constitute a problem for the orbiter during take-off or climb to altitude. The impact that the tow concept would have on the cost and schedule of the space shuttle program was not evaluated in this study.

  8. 46 CFR 2.01-50 - Persons other than crew on towing, oyster, or fishing steam vessels.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Persons other than crew on towing, oyster, or fishing steam vessels. 2.01-50 Section 2.01-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES... than crew on towing, oyster, or fishing steam vessels. (a) A steam vessel engaged in towing,...

  9. 46 CFR 2.01-50 - Persons other than crew on towing, oyster, or fishing steam vessels.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Persons other than crew on towing, oyster, or fishing steam vessels. 2.01-50 Section 2.01-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES... than crew on towing, oyster, or fishing steam vessels. (a) A steam vessel engaged in towing,...

  10. 46 CFR 2.01-50 - Persons other than crew on towing, oyster, or fishing steam vessels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Persons other than crew on towing, oyster, or fishing steam vessels. 2.01-50 Section 2.01-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES... than crew on towing, oyster, or fishing steam vessels. (a) A steam vessel engaged in towing,...

  11. 46 CFR 2.01-50 - Persons other than crew on towing, oyster, or fishing steam vessels.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Persons other than crew on towing, oyster, or fishing steam vessels. 2.01-50 Section 2.01-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES... than crew on towing, oyster, or fishing steam vessels. (a) A steam vessel engaged in towing,...

  12. 46 CFR 2.01-50 - Persons other than crew on towing, oyster, or fishing steam vessels.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Persons other than crew on towing, oyster, or fishing steam vessels. 2.01-50 Section 2.01-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES... than crew on towing, oyster, or fishing steam vessels. (a) A steam vessel engaged in towing,...

  13. 46 CFR 27.211 - What are the specifications for fuel systems on towing vessels whose construction was contracted...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... uses bunker C, heavy fuel oil (HFO), or any fuel that requires pre-heating, must comply with subchapter... 46 Shipping 1 2010-10-01 2010-10-01 false What are the specifications for fuel systems on towing... for Towing Vessels § 27.211 What are the specifications for fuel systems on towing vessels...

  14. 46 CFR 27.211 - What are the specifications for fuel systems on towing vessels whose construction was contracted...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... uses bunker C, heavy fuel oil (HFO), or any fuel that requires pre-heating, must comply with subchapter... 46 Shipping 1 2013-10-01 2013-10-01 false What are the specifications for fuel systems on towing... for Towing Vessels § 27.211 What are the specifications for fuel systems on towing vessels...

  15. 46 CFR 27.211 - What are the specifications for fuel systems on towing vessels whose construction was contracted...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... uses bunker C, heavy fuel oil (HFO), or any fuel that requires pre-heating, must comply with subchapter... 46 Shipping 1 2014-10-01 2014-10-01 false What are the specifications for fuel systems on towing... for Towing Vessels § 27.211 What are the specifications for fuel systems on towing vessels...

  16. Optimization of Elastically Tailored Tow-Placed Plates with Holes

    NASA Technical Reports Server (NTRS)

    Jegley, Dawn C.; Tatting, Brian F.; Guerdal, Zafer

    2003-01-01

    Elastic stiffness tailoring of laminated composite panels by allowing the fibers to curve within the plane of the laminate is a design concept that has been demonstrated to be both beneficial and practical. The objective of the present paper is to demonstrate the effectiveness of stiffness tailoring through the use of curvilinear fibers to reduce stress concentrations around the hole and improve the load carrying capability of panels. Preliminary panel designs that are to be manufactured and tested were determined through design studies for flat plates without holes under axial compression using an optimization program. These candidate designs were then analyzed with finite element models that accurately reflect the test conditions and geometries in order to decide upon the final designs for manufacture and testing. An advanced tow-placement machine is used to manufacture the test panels with varying fiber orientation angles. A total of six large panels measuring three feet by six feet, each of which is used to produce four specimens with or without holes, are fabricated. The panels were machined into specimens with holes and tested at NASA Langley Research Center. Buckling response and failure of panels without holes and with two different hole dimensions are presented. Buckling and failure loads of tow-steered specimens are significantly greater than the buckling and failure loads of traditional straight-fiber specimens.

  17. An experimental investigation of the equilibrium and stability of long towed cable systems

    NASA Astrophysics Data System (ADS)

    Obligado, Martin; Bourgoin, Mickaël

    2013-04-01

    The dynamics of towed objects in a fluid environment is of interest for many practical situations. We investigate experimentally the equilibrium and stability of the trajectory of a sphere towed at constant velocity at the tip of a cable with an unprecedented large length-to-diameter aspect ratio, exceeding 104. The towing configuration is artificially obtained by considering a steady cable (with one fixed end and a free end to which a sphere is eventually attached) in a low-turbulence wind tunnel. We consider three different configurations: (i) the cable towed by itself; (ii) a light millimetric towed sphere made of expanded polystyrene; and (iii) a denser millimetric towed sphere made of lead. The trajectory of the cable tip is monitored using high-speed Lagrangian tracking, which allows one to characterize the average position and the dynamical fluctuations of the towed object. We show that the mean equilibrium position is well predicted by a simple model including the aerodynamical forces acting along the cable and on the towed sphere (when present). Concerning stability issues, we find that the heavy lead particle is always towed in stable conditions (within the accessible range of velocities) with only very low energy oscillations related to a weak pendulum-like motion. In contrast, the free end and light sphere cases are shown to become unstable when the towing velocity exceeds a certain threshold. Spectral analysis shows a flutter-type instability for the sphere, with a dominant oscillatory motion, while the cable alone develops a divergence-type instability with random fluctuations.

  18. F-106 tow cable attachment and release mechanism for Eclipse program

    NASA Technical Reports Server (NTRS)

    1997-01-01

    View of the tow cable attachment and release mechanism forward of the cockpit on the QF-106 Eclipse aircraft. This mechanism held and then released the Vectran rope used to tow the QF-106 behind an Air Force C-141A. In 1997 and 1998, the Dryden Flight Research Center at Edwards, California, supported and hosted a Kelly Space & Technology, Inc. project called Eclipse, which sought to demonstrate the feasibility of a reusable tow-launch vehicle concept. The project goal was to successfully tow, inflight, a modified QF-106 delta-wing aircraft with an Air Force C-141A transport aircraft. This would demonstrate the possibility of towing and launching an actual launch vehicle from behind a tow plane. Dryden was the responsible test organization and had flight safety responsibility for the Eclipse project. Dryden provided engineering, instrumentation, simulation, modification, maintenance, range support, and research pilots for the test program. The Air Force Flight Test Center (AFFTC), Edwards, California, supplied the C-141A transport aircraft and crew and configured the aircraft as needed for the tests. The AFFTC also provided the concept and detail design and analysis as well as hardware for the tow system and QF-106 modifications. Dryden performed the modifications to convert the QF-106 drone into the piloted EXD-01 (Eclipse eXperimental Demonstrator-01) experimental aircraft. Kelly Space & Technology hoped to use the results gleaned from the tow test in developing a series of low-cost, reusable launch vehicles. These tests demonstrated the validity of towing a delta-wing aircraft having high wing loading, validated the tow simulation model, and demonstrated various operational procedures, such as ground processing of in-flight maneuvers and emergency abort scenarios.

  19. M2-F1 in flight on tow line

    NASA Technical Reports Server (NTRS)

    1964-01-01

    The M2-F1 Lifting Body is seen here under tow at the Flight Research Center (later redesignated the Dryden Flight Research Center), Edwards, California. The wingless, lifting-body aircraft design was initially concieved as a means of landing an aircraft horizontally after atmospheric reentry. The absence of wings would make the extreme heat of re-entry less damaging to the vehicle. In 1962, Flight Research Center management approved a program to build a lightweight, unpowered lifting body as a prototype to flight test the wingless concept. It would look like a 'flying bathtub,' and was designated the M2-F1, the 'M' referring to 'manned' and 'F' referring to 'flight' version. It featured a plywood shell placed over a tubular steel frame crafted at Dryden. Construction was completed in 1963. The M2-F1 project had limited goals. They were to show that a piloted lifting body could be built, that it could not only fly but be controlled in flight, and that it could make a successful landing. While the M2-F1 did prove the concept, with a wooden fuselage and fixed landing gear, it was far from an operational spacecraft. The next step in the lifting-body development was to build a heavyweight, rocket-powered vehicle that was more like an operational lifting body, albeit one without the thermal protection system that would be needed for reentry into the atmosphere from space at near-orbital speeds. The first flight tests of the M2-F1 were over Rogers Dry Lake at the end of a tow rope attached to a hopped-up Pontiac convertible driven at speeds up to about 120 mph. These initial tests produced enough flight data about the M2-F1 to proceed with flights behind a NASA C-47 tow plane at greater altitudes. The C-47 took the craft to an altitude of 12,000 where free flights back to Rogers Dry Lake began. Pilot for the first series of flights of the M2-F1 was NASA research pilot Milt Thompson. Typical glide flights with the M2-F1 lasted about two minutes and reached speeds of 110 to

  20. Performance characteristics of a three-axis superconducting rock magnetometer

    NASA Technical Reports Server (NTRS)

    Lienert, B. R.

    1977-01-01

    A series of measurements are carried out with the purpose of quantitatively determining the characteristics of a commercial 6.8 cm access superconducting rock magnetometer located in the magnetic properties laboratory at the Goddard Space Flight Center. The measurements show that although a considerable improvement in measurement speed and signal to noise ratios can be obtained using such an instrument, a number of precautions are necessary to obtain accuracies comparable with more conventional magnetometers. These include careful calibration of the sensor outputs, optimum positioning of the sample within the detection region and quantitatively establishing the degree of cross-coupling between the detector coils. In order to examine the uniformity of response for each detector, the responses are mapped as a function of position, using a small dipole.

  1. Data Acquisition System for Russian Arctic Magnetometer Network

    NASA Astrophysics Data System (ADS)

    Janzhura, A.; Troshichev, O. A.; Takahashi, K.

    2010-12-01

    Monitoring of magnetic activity in the auroral zone is very essential for space weather problem. The big part of northern auroral zone lies in the Russian sector of Arctica. The Russian auroral zone stations are located far from the proper infrastructure and communications, and getting the data from the stations is complicated and nontrivial task. To resolve this problem a new acquisition system for magnetometers was implemented and developed in last few years, with the magnetic data transmission in real time that is important for many forecasting purpose. The system, based on microprocessor modules, is very reliable in hush climatic conditions. The information from the magnetic sensors transmits to AARI data center by satellite communication system and is presented at AARI web pages. This equipment upgrading of Russian polar magnetometer network is supported by the international RapidMag program.

  2. Hansteen's magnetometer and the origin of the magnetic crusade.

    PubMed

    Enebakk, Vidar

    2014-12-01

    In the early nineteenth century, Norwegian mathematician and astronomer Christopher Hansteen (1784-1873) contributed significantly to international collaboration in the study of terrestrial magnetism. In particular, Hansteen was influential in the origin and orientation of the magnetic lobby in Britain, a campaign which resulted in a global network of fixed geomagnetic observatories. In retrospect, however, his contribution was diminished, because his four-pole theory in Untersuchungen der Magnetismus der Erde (1819) was ultimately refuted by Carl Friedrich Gauss in Allgemeine Theorie des Erdmagnetismus (1839). Yet Hansteen's main contribution was practical rather than theoretical. His major impact was related to the circulation of his instruments and techniques. From the mid-1820s, 'Hansteen's magnetometer' was distributed all over the British Isles and throughout the international scientific community devoted to studying terrestrial magnetism. Thus in the decades before the magnetic crusade, Hansteen had established an international system of observation, standardization and representation based on measurements with his small and portable magnetometers.

  3. On-chip magnetometer for characterization of superparamagnetic nanoparticles.

    PubMed

    Kim, Kun Woo; Reddy, Venu; Torati, Sri Ramulu; Hu, Xing Hao; Sandhu, Adarsh; Kim, Cheol Gi

    2015-02-07

    An on-chip magnetometer was fabricated by integrating a planar Hall magnetoresistive (PHR) sensor with microfluidic channels. The measured in-plane field sensitivities of an integrated PHR sensor with NiFe/Cu/IrMn trilayer structure were extremely high at 8.5 μV Oe(-1). The PHR signals were monitored during the oscillation of 35 pL droplets of magnetic nanoparticles, and reversed profiles for the positive and negative z-fields were measured, where magnitudes increased with the applied z-field strength. The measured PHR signals for 35 pL droplets of magnetic nanoparticles versus applied z-fields showed excellent agreement with magnetization curves measured by a vibrating sample magnetometer (VSM) of 3 μL volume, where a PHR voltage of 1 μV change is equivalent to 0.309 emu cc(-1) of the volume magnetization with a magnetic moment resolution of ~10(-10) emu.

  4. Laser pumped (4)He magnetometer with light shift suppression.

    PubMed

    Lin, Zaisheng; Wang, He; Peng, Xiang; Wu, Teng; Guo, Hong

    2016-11-01

    We report a laser-pumped (4)He atomic magnetometer with light shift suppression through the atomic sensor itself. A linearly polarized light is used to optically align the (4)He metastable atoms and we monitor the magneto-optical double resonance (MODR) signals produced by the left- and right-circularly orthogonal components. It is shown that light shift leads to the atomic alignment to orientation conversion effect, and thus, the difference between the two MODR signals. One of these two MODR signals is locked at the Larmor frequency and is used to measure the ambient magnetic field, while the differential signal is, simultaneously, fed back to suppress the light shift. The scheme could be of the advantage to the design of compact magnetometers by reducing the systematic errors due to light shift.

  5. Space magnetometer based on an anisotropic magnetoresistive hybrid sensor.

    PubMed

    Brown, P; Whiteside, B J; Beek, T J; Fox, P; Horbury, T S; Oddy, T M; Archer, M O; Eastwood, J P; Sanz-Hernández, D; Sample, J G; Cupido, E; O'Brien, H; Carr, C M

    2014-12-01

    We report on the design and development of a low resource, dual sensor vector magnetometer for space science applications on very small spacecraft. It is based on a hybrid device combining an orthogonal triad of commercial anisotropic magnetoresistive (AMR) sensors with a totem pole H-Bridge drive on a ceramic substrate. The drive enables AMR operation in the more sensitive flipped mode and this is achieved without the need for current spike transmission down a sensor harness. The magnetometer has sensitivity of better than 3 nT in a 0-10 Hz band and a total mass of 104 g. Three instruments have been launched as part of the TRIO-CINEMA space weather mission, inter-calibration against the International Geomagnetic Reference Field model makes it possible to extract physical signals such as field-aligned current deflections of 20-60 nT within an approximately 45,000 nT ambient field.

  6. Remote detection of rotating machinery with a portable atomic magnetometer.

    PubMed

    Marmugi, Luca; Gori, Lorenzo; Hussain, Sarah; Deans, Cameron; Renzoni, Ferruccio

    2017-01-20

    We demonstrate remote detection of rotating machinery, using an atomic magnetometer at room temperature and in an unshielded environment. The system relies on the coupling of the AC magnetic signature of the target with the spin-polarized, precessing atomic vapor of a radio-frequency optical atomic magnetometer. The AC magnetic signatures of rotating equipment or electric motors appear as sidebands in the power spectrum of the atomic sensor, which can be tuned to avoid noisy bands that would otherwise hamper detection. A portable apparatus is implemented and experimentally tested. Proof-of-concept investigations are performed with test targets mimicking possible applications, and the operational conditions for optimum detection are determined. Our instrument provides comparable or better performance than a commercial fluxgate and allows detection of rotating machinery behind a wall. These results demonstrate the potential for ultrasensitive devices for remote industrial and usage monitoring, security, and surveillance.

  7. Results from the GSFC fluxgate magnetometer on Pioneer 11

    NASA Technical Reports Server (NTRS)

    Acuna, M. H.; Ness, N. F.

    1976-01-01

    A high-field triaxial fluxgate magnetometer was mounted on Pioneer 11 to measure the main magnetic field of Jupiter. It is found that this planetary magnetic field is more complex than that indicated by the results of the Pioneer 10 vector helium magnetometer. At distances less than 3 Jupiter radii, the magnetic field is observed to increase more rapidly than an inverse-cubed distance law associated with any simple dipole model. Contributions from higher-order multipoles are significant, with the quadrupole and octupole being 24 and 21 percent of the dipole moment, respectively. Implications of the results for the study of trapped particles, planetary radio emission, and planetary interiors are discussed. Major conclusions are that the deviation of the main planetary magnetic field from a simple dipole leads to distortion of the L shells of the charged particles and to warping of the magnetic equator. Enhanced absorption effects associated with Amalthea and Io are predicted.

  8. Construction of an AMR magnetometer for car detection experiments

    NASA Astrophysics Data System (ADS)

    Fúra, V.; Petrucha, V.; Platil, A.

    2016-03-01

    A new construction of magnetometer with commercially available AMR (anisotropic magnetoresistive) sensors intended for vehicle detection experiments is presented. Initial experiments with simple AMR gradiometer indicated viability of the approach in a real- world setup. For further experiments and acquisition of representative data, a new design of precise multi-channel magnetometer was developed. The design supports two models of commercial AMR sensors: the proven and reliable, but obsolete Honeywell HMC1021-series sensors and newly available Sensitec AFF755B sensors. In the comparison the two types are similar in most achieved parameters, except offset stability in flipped operation regime. Unfortunately, the new AFF755B sensors seem to have perhaps inferior coupling of the flipping (set/reset) coil to the ferromagnetic core that causes insufficient saturation of the AMR material. The issue is being solved by Sensitec, current deliverables of the AFF755B have “product sample” status (September 2015).

  9. Space magnetometer based on an anisotropic magnetoresistive hybrid sensor

    NASA Astrophysics Data System (ADS)

    Brown, P.; Whiteside, B. J.; Beek, T. J.; Fox, P.; Horbury, T. S.; Oddy, T. M.; Archer, M. O.; Eastwood, J. P.; Sanz-Hernández, D.; Sample, J. G.; Cupido, E.; O'Brien, H.; Carr, C. M.

    2014-12-01

    We report on the design and development of a low resource, dual sensor vector magnetometer for space science applications on very small spacecraft. It is based on a hybrid device combining an orthogonal triad of commercial anisotropic magnetoresistive (AMR) sensors with a totem pole H-Bridge drive on a ceramic substrate. The drive enables AMR operation in the more sensitive flipped mode and this is achieved without the need for current spike transmission down a sensor harness. The magnetometer has sensitivity of better than 3 nT in a 0-10 Hz band and a total mass of 104 g. Three instruments have been launched as part of the TRIO-CINEMA space weather mission, inter-calibration against the International Geomagnetic Reference Field model makes it possible to extract physical signals such as field-aligned current deflections of 20-60 nT within an approximately 45 000 nT ambient field.

  10. Assessing and Ensuring GOES-R Magnetometer Accuracy

    NASA Technical Reports Server (NTRS)

    Kronenwetter, Jeffrey; Carter, Delano R.; Todirita, Monica; Chu, Donald

    2016-01-01

    The GOES-R magnetometer accuracy requirement is 1.7 nanoteslas (nT). During quiet times (100 nT), accuracy is defined as absolute mean plus 3 sigma. During storms (300 nT), accuracy is defined as absolute mean plus 2 sigma. To achieve this, the sensor itself has better than 1 nT accuracy. Because zero offset and scale factor drift over time, it is also necessary to perform annual calibration maneuvers. To predict performance, we used covariance analysis and attempted to corroborate it with simulations. Although not perfect, the two generally agree and show the expected behaviors. With the annual calibration regimen, these predictions suggest that the magnetometers will meet their accuracy requirements.

  11. Versatile magnetometer assembly for characterizing magnetic properties of nanoparticles

    SciTech Connect

    Araujo, J. F. D. F.; Bruno, A. C.; Louro, S. R. W.

    2015-10-15

    We constructed a versatile magnetometer assembly for characterizing iron oxide nanoparticles. The magnetometer can be operated at room temperature or inside a cryocooler at temperatures as low as 6 K. The magnetometer’s sensor can be easily exchanged and different detection electronics can be used. We tested the assembly with a non-cryogenic commercial Hall sensor and a benchtop multimeter in a four-wire resistance measurement scheme. A magnetic moment sensitivity of 8.5 × 10{sup −8} Am{sup 2} was obtained with this configuration. To illustrate the capability of the assembly, we synthesized iron oxide nanoparticles coated with different amounts of a triblock copolymer, Pluronic F-127, and characterized their magnetic properties. We determined that the polymer coating does not affect the magnetization of the particles at room temperature and demonstrates that it is possible to estimate the average size of coating layers from measurements of the magnetic field of the sample.

  12. Specimen size and improved precision with the Molspin spinner magnetometer

    NASA Astrophysics Data System (ADS)

    Borradaile, G. J.; Almqvist, B. S.; Lucas, K.

    2006-01-01

    Manual reorientation of traditional 10.5 cm 3 paleomagnetic cores between successive spins in Molspin-type magnetometers produces some operator error that may be significantly reduced if smaller core (5.1 cm 3) is used instead. The smaller core may be locked into a cubical holder that ensures its precise angular alignment between successive spins of the magnetometer. This significantly improves precision of the mean vector direction for replicate measurements, or for a suite of specimens, provided that the magnetic mineralogy of the rock is sufficiently homogenous to be meaningfully characterized in the smaller (5.1 cm 3) core. The smaller core is more quickly measured and less expensive to drill.

  13. Integrated induction coil and fluxgate magnetometers for EM analysis and monitoring

    NASA Astrophysics Data System (ADS)

    Hanstein, T.; Strack, K.; Jiang, J.

    2013-12-01

    The concept of a full field array electromagnetic system is an ideal tool to support hydrocarbon and geothermal E & P as well as various engineering monitoring applications. Some of the key questions are defining the reservoir, mapping of the fractures and reservoir depletion monitoring. The reservoirs are all too often relative thin and give an anomalous electromagnetic (EM) response, which is often small in amplitude and challenging for the EM measuring system. A digital fluxgate magnetometer (32-bit) is connected to the KMS magnetotelluric acquisition system with analogue induction coils and electrodes to extend the range of application of a single recording site. Since the noise level is above that of the induction coil for periods shorter than 20 s, the apparent resistivity is biased. For longer periods the apparent resistivity is consistent and eventually better than the induction coil. However, phase and tipper are not biased and agree well with the induction data even for shorter periods. This allows us to develop algorithms that significantly extend the range of application of the fluxgate beyond what was done in the past. The highest frequency of the fluxgate magnetometer is about 180 Hz and the hightest sampling of the FG-board is 4 kHz.The different induction coils and fluxgate magnetometer have intensively been tested in the magnetic chamber and at the field test site near Houston for noise performance by parallel recordings. They show that even in an environment with high cultural noise, the specification can be met. In Northeast China, a 30-day monitoring test with MT was carried out for seismologic applications. Acquisitition schedule included different recordings times and sampling rates. Daily, the data was collected and processed via the internet from either Europe or the US. Even with long recording, we still had to select the time windows for data averaging and coherences are not a good threshhold criteria in this case. During another MT

  14. Using Redundancy To Reduce Errors in Magnetometer Readings

    NASA Technical Reports Server (NTRS)

    Kulikov, Igor; Zak, Michail

    2004-01-01

    A method of reducing errors in noisy magnetic-field measurements involves exploitation of redundancy in the readings of multiple magnetometers in a cluster. By "redundancy"is meant that the readings are not entirely independent of each other because the relationships among the magnetic-field components that one seeks to measure are governed by the fundamental laws of electromagnetism as expressed by Maxwell's equations. Assuming that the magnetometers are located outside a magnetic material, that the magnetic field is steady or quasi-steady, and that there are no electric currents flowing in or near the magnetometers, the applicable Maxwell 's equations are delta x B = 0 and delta(raised dot) B = 0, where B is the magnetic-flux-density vector. By suitable algebraic manipulation, these equations can be shown to impose three independent constraints on the values of the components of B at the various magnetometer positions. In general, the problem of reducing the errors in noisy measurements is one of finding a set of corrected values that minimize an error function. In the present method, the error function is formulated as (1) the sum of squares of the differences between the corrected and noisy measurement values plus (2) a sum of three terms, each comprising the product of a Lagrange multiplier and one of the three constraints. The partial derivatives of the error function with respect to the corrected magnetic-field component values and the Lagrange multipliers are set equal to zero, leading to a set of equations that can be put into matrix.vector form. The matrix can be inverted to solve for a vector that comprises the corrected magnetic-field component values and the Lagrange multipliers.

  15. Theory of double resonance magnetometers based on atomic alignment

    SciTech Connect

    Weis, Antoine; Bison, Georg; Pazgalev, Anatoly S.

    2006-09-15

    We present a theoretical study of the spectra produced by optical-radio-frequency double resonance devices, in which resonant linearly polarized light is used in the optical pumping and detection processes. We extend previous work by presenting algebraic results which are valid for atomic states with arbitrary angular momenta, arbitrary rf intensities, and arbitrary geometries. The only restriction made is the assumption of low light intensity. The results are discussed in view of their use in optical magnetometers.

  16. A computer control system for the alternating gradient magnetometer

    NASA Astrophysics Data System (ADS)

    Garland, Michael M.

    1989-12-01

    An alternating gradient magnetometer was interfaced to a computer for the automation of data taking. Using a fast Fourier transform analysis system data can be acquired and processed in real time. Data are stored on disk and can be recalled for plotting and further analysis. With the addition of a simple liquid nitrogen cryostat, magnetization measurements can be performed in the range from 300 to 77 K. Results are reported on three different types of piezoelectric transducers.

  17. Search for plant biomagnetism with a sensitive atomic magnetometer

    DTIC Science & Technology

    2011-01-01

    Measurements with a sensitive atomic magnetometer were performed on the Titan arum (Amorphophallus titanum) inflorescence , known for its fast biochemical...unbranched inflorescence in the world. The inflorescence’s single flowers (500 female and 500 male), located at the base of the spadix and enrobed...24“ Inflorescence Terminology,” http://waynesword.palomar.edu/terminf1.htm. 25R. Seymour, J. Exp. Bot. 52, 1465 (2001). 26R. Seymour, Thermochim

  18. A computer control system for the alternating gradient magnetometer

    NASA Technical Reports Server (NTRS)

    Garland, Michael M.

    1989-01-01

    An alternating gradient magnetometer was interfaced to a computer for the automation of data taking. Using a fast Fourier transform analysis system data can be acquired and processed in real time. Data are stored on disk and can be recalled for plotting and further analysis. With the addition of a simple liquid nitrogen cryostat, magnetization measurements can be performed in the range from 300 to 77 K. Results are reported on three different types of piezoelectric transducers.

  19. Search for plant biomagnetism with a sensitive atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Corsini, Eric; Acosta, Victor; Baddour, Nicolas; Higbie, James; Lester, Brian; Licht, Paul; Patton, Brian; Prouty, Mark; Budker, Dmitry

    2011-04-01

    We report what we believe is the first experimental limit placed on plant biomagnetism. Measurements with a sensitive atomic magnetometer were performed on the Titan arum (Amorphophallus titanum) inflorescence, known for its fast biochemical processes while blooming. We find that the magnetic field from these processes, projected along the Earth's magnetic field, and measured at the surface of the plant, is ≲ 0.6 μG.

  20. An Automated Home Made Low Cost Vibrating Sample Magnetometer

    NASA Astrophysics Data System (ADS)

    Kundu, S.; Nath, T. K.

    2011-07-01

    The design and operation of a homemade low cost vibrating sample magnetometer is described here. The sensitivity of this instrument is better than 10-2 emu and found to be very efficient for the measurement of magnetization of most of the ferromagnetic and other magnetic materials as a function of temperature down to 77 K and magnetic field upto 800 Oe. Both M(H) and M(T) data acquisition are fully automated employing computer and Labview software.

  1. Swarm Optimization-Based Magnetometer Calibration for Personal Handheld Devices

    PubMed Central

    Ali, Abdelrahman; Siddharth, Siddharth; Syed, Zainab; El-Sheimy, Naser

    2012-01-01

    Inertial Navigation Systems (INS) consist of accelerometers, gyroscopes and a processor that generates position and orientation solutions by integrating the specific forces and rotation rates. In addition to the accelerometers and gyroscopes, magnetometers can be used to derive the user heading based on Earth's magnetic field. Unfortunately, the measurements of the magnetic field obtained with low cost sensors are usually corrupted by several errors, including manufacturing defects and external electro-magnetic fields. Consequently, proper calibration of the magnetometer is required to achieve high accuracy heading measurements. In this paper, a Particle Swarm Optimization (PSO)-based calibration algorithm is presented to estimate the values of the bias and scale factor of low cost magnetometers. The main advantage of this technique is the use of the artificial intelligence which does not need any error modeling or awareness of the nonlinearity. Furthermore, the proposed algorithm can help in the development of Pedestrian Navigation Devices (PNDs) when combined with inertial sensors and GPS/Wi-Fi for indoor navigation and Location Based Services (LBS) applications.

  2. A YBCO RF-SQUID magnetometer and its applications

    NASA Technical Reports Server (NTRS)

    Luwei, Zhou; Jingwu, Qiu; Xienfeng, Zhang; Zhiming, Tank; Yongjia, Qian

    1990-01-01

    An applicable RF-superconducting quantum interference detector (SQUID) magnetometer was made using a bulk sintered yttrium barium copper oxide (YBCO). The temperature range of the magnetometer is 77 to 300 K and the field range 0 to 0.1T. At 77 K, the equivalent flux noise of the SQUID is 5 x 10 to minus 4 power theta sub o/square root of Hz at the frequency range of 20 to 200 Hz. The experiments show that the SQUID noise at low-frequency end is mainly from 1/f noise. A coil test shows that the magnetic moment sensitivity delta m is 10 to the minus 6th power emu. The RF-SQUID is shielded in a YBCO cylinder with a shielding ability B sub in/B sub ex of about 10 to the minus 6th power when external dc magnetic field is about a few Oe. The magnetometer is successfully used in characterizing superconducting thin films.

  3. Results of the Magnetometer Navigation (MAGNAV)lnflight Experiment

    NASA Technical Reports Server (NTRS)

    Thienel, Julie K.; Harman, Richard R.; Bar-Itzhack, Itzhack Y.; Lambertson, Mike

    2004-01-01

    The Magnetometer Navigation (MAGNAV) algorithm is currently running as a flight experiment as part of the Wide Field Infrared Explorer (WIRE) Post-Science Engineering Testbed. Initialization of MAGNAV occurred on September 4, 2003. MAGNAV is designed to autonomously estimate the spacecraft orbit, attitude, and rate using magnetometer and sun sensor data. Since the Earth's magnetic field is a function of time and position, and since time is known quite precisely, the differences between the computed magnetic field and measured magnetic field components, as measured by the magnetometer throughout the entire spacecraft orbit, are a function of the spacecraft trajectory and attitude errors. Therefore, these errors are used to estimate both trajectory and attitude. In addition, the time rate of change of the magnetic field vector is used to estimate the spacecraft rotation rate. The estimation of the attitude and trajectory is augmented with the rate estimation into an Extended Kalman filter blended with a pseudo-linear Kalman filter. Sun sensor data is also used to improve the accuracy and observability of the attitude and rate estimates. This test serves to validate MAGNAV as a single low cost navigation system which utilizes reliable, flight qualified sensors. MAGNAV is intended as a backup algorithm, an initialization algorithm, or possibly a prime navigation algorithm for a mission with coarse requirements. Results from the first six months of operation are presented.

  4. Results of the Magnetometer Navigation (MAGNAV) Inflight Experiment

    NASA Technical Reports Server (NTRS)

    Thienel, Julie; Harman, Rick; Bar-Itzhack, Itzhack

    2004-01-01

    The Magnetometer Navigation (MAGNAV) algorithm is currently running as a flight experiment as part of the Wide Field Infrarad Explorer Post-Science Engineer- ing Testbed. Initialization of MAGNAV occured on September 4, 2004. MAGNAV is designed to autonomously estimate the spacecraft orbit, attitude, and rate using magnetometer and sun sensor data. Since the earth s magnetic field is a function of time and position, and since time is known quite precisely, the differences between the computed magnetic field and measured magnetic field components, as measured by the magnetometer throughout the entire spacecraft orbit, are a function of the spacecraft trajectory and attitude errors. Therefore, these errors are used to estimate both trajec- tory and attitude. In addition, the time rate of change of the magnetic field vector is used to estimate the spacecraft rotation rate. The estimation of the attitude and tra- jectory is augmented with the rate estimation into an Extended Kalman filter blended with a pseudc-linear Kalman filter. Sun sensor data is also used to improve the accu- racy and observability of the attitude and rate estimates. This test serves to validate MAGNAV as a single low cost navigation system which utilizes reliable, flight qualified sensors. MAGNAV is intended as a backup algorithm, an initialization algorithm, or possibly a prime navigation algorithm for a mission with coarse constraints.

  5. GPS/Magnetometer Based Satellite Navigation and Attitude Determination

    NASA Technical Reports Server (NTRS)

    Deutschmann, Julie; Bar-Itzhack, Itzhack; Harman, Rick; Bauer, Frank H. (Technical Monitor)

    2001-01-01

    In recent years algorithms were developed for orbit, attitude and angular-rate determination of Low Earth Orbiting (LEO) satellites. Those algorithms rely on measurements of magnetometers, which are standard, relatively inexpensive, sensors that are normally installed on every LEO satellite. Although magnetometers alone are sufficient for obtaining the desired information, the convergence of the algorithms to the correct values of the satellite orbital parameters, position, attitude and angular velocity is very slow. The addition of sun sensors reduces the convergence time considerably. However, for many LEO satellites the sun data is not available during portions of the orbit when the spacecraft (SC) is in the earth shadow. It is here where the GPS space vehicles (SV) can provide valuable support. This is clearly demonstrated in the present paper. Although GPS measurements alone can be used to obtain SC position, velocity, attitude and angular-rate, the use of magnetometers improve the results due to the synergistic effect of sensor fusion. Moreover, it is possible to obtain these results with less than three SVs. In this paper we introduce an estimation algorithm, which is a combination of an Extended Kalman Filter (EKF) and a Pseudo Linear Kalman Filter (PSELIKA).

  6. In-Flight Calibration Processes for the MMS Fluxgate Magnetometers

    NASA Technical Reports Server (NTRS)

    Bromund, K. R.; Leinweber, H. K.; Plaschke, F.; Strangeway, R. J.; Magnes, W.; Fischer, D.; Nakamura, R.; Anderson, B. J.; Russell, C. T.; Baumjohann, W.; Chutter, M.; Torbert, R. B.; Le, G.; Slavin, J. A.; Kepko, E. L.

    2015-01-01

    The calibration effort for the Magnetospheric Multiscale Mission (MMS) Analog Fluxgate (AFG) and DigitalFluxgate (DFG) magnetometers is a coordinated effort between three primary institutions: University of California, LosAngeles (UCLA); Space Research Institute, Graz, Austria (IWF); and Goddard Space Flight Center (GSFC). Since thesuccessful deployment of all 8 magnetometers on 17 March 2015, the effort to confirm and update the groundcalibrations has been underway during the MMS commissioning phase. The in-flight calibration processes evaluatetwelve parameters that determine the alignment, orthogonalization, offsets, and gains for all 8 magnetometers usingalgorithms originally developed by UCLA and the Technical University of Braunschweig and tailored to MMS by IWF,UCLA, and GSFC. We focus on the processes run at GSFC to determine the eight parameters associated with spin tonesand harmonics. We will also discuss the processing flow and interchange of parameters between GSFC, IWF, and UCLA.IWF determines the low range spin axis offsets using the Electron Drift Instrument (EDI). UCLA determines the absolutegains and sensor azimuth orientation using Earth field comparisons. We evaluate the performance achieved for MMS andgive examples of the quality of the resulting calibrations.

  7. Polarization enhanced Nuclear Quadrupole Resonance with an atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Malone, Michael W.; Barrall, Geoffrey A.; Espy, Michelle A.; Monti, Mark C.; Alexson, Dimitri A.; Okamitsu, Jeffrey K.

    2016-05-01

    Nuclear Quadrupole Resonance (NQR) has been demonstrated for the detection of 14-N in explosive compounds. Application of a material specific radio-frequency (RF) pulse excites a response typically detected with a wire- wound antenna. NQR is non-contact and material specific, however fields produced by NQR are typically very weak, making demonstration of practical utility challenging. For certain materials, the NQR signal can be increased by transferring polarization from hydrogen nuclei to nitrogen nuclei using external magnetic fields. This polarization enhancement (PE) can enhance the NQR signal by an order of magnitude or more. Atomic magnetometers (AM) have been shown to improve detection sensitivity beyond a conventional antenna by a similar amount. AM sensors are immune to piezo-electric effects that hamper conventional NQR, and can be combined to form a gradiometer for effective RF noise cancellation. In principle, combining polarization enhancement with atomic magnetometer detection should yield improvement in signal-to-noise ratio that is the product of the two methods, 100-fold or more over conventional NQR. However both methods are even more exotic than traditional NQR, and have never been combined due to challenges in operating a large magnetic field and ultra-sensitive magnetic field sensor in proximity. Here we present NQR with and without PE with an atomic magnetometer, demonstrating signal enhancement greater than 20-fold for ammonium nitrate. We also demonstrate PE for PETN using a traditional coil for detection with an enhancement factor of 10. Experimental methods and future applications are discussed.

  8. ULF wave interaction with the ionosphere: radar and magnetometer observations

    NASA Astrophysics Data System (ADS)

    Pilipenko, Viacheslav; Fedorov, Evgeniy; Kozlovsky, Alexander; Belakhovsky, Vladimir; Teramoto, Mariko

    Combined usage of SuperDARN/EISCAT radars and magnetometers, supported by an adequate theory of ULF wave interaction with the multi-layer system magnetosphere - ionosphere - atmosphere - ground, is an effective way to reveal a physical mechanism of ULF disturbances. Many notions derived only from satellite or ground observations may be challenged by additional information from radars (e.g., association of ULF phenomena with magnetospheric domains, ULF wave spatial structure, etc.). To identify the physical nature of global Pc5 pulsations at the recovery phase of strong magnetic storms and to determine relative contributions of different MHD modes into their structure, the method of apparent impedance can be applied. These Pc5 pulsations are considered using the IMAGE magnetometer data and EISCAT radar data from Tromso-Kiruna-Sodankyla system. An approximate analytical relationship derived from the theory of ULF wave transmission through the thin ionosphere has been compared with the measured ratio between the simultaneous ionospheric electric and ground magnetic fields. The impedances of Alfven and compressional modes are to be essentially distinct. From these observations we conclude that the global Pc5 pulsations above the ionosphere are predominantly composed from Alfven waves with a small contribution of fast compressional mode. Combined SuperDARN Hokkaido radar and magnetometer observations of mid-latitude Pi2 pulsations showed that the concept of a pure cavity mode is not sufficient to explain these observations, and that the contribution of an Alfvén waves must be taken in account. ULF waves are not just sounding signals, but an active factor of the near-Earth environment. The comparison of magnetometer data with the ionospheric parameters shows a significant modulation of the electron density, ionospheric height-integrated conductance, and ion temperature by Pc5 pulsations, even in the absence of quasi-periodic electron precipitation. The mechanisms

  9. Design and Analysis of Tow-Steered Composite Shells Using Fiber Placement

    NASA Technical Reports Server (NTRS)

    Wu, K. Chauncey

    2008-01-01

    In this study, a sub-scale advanced composite shell design is evaluated to determine its potential for use on a future aircraft fuselage. Two composite shells with the same nominal 8-ply [+/-45/+/-Theta](sub s) layup are evaluated, where Theta indicates a tow-steered ply. To build this shell, a fiber placement machine would be used to steer unidirectional prepreg tows as they are placed around the circumference of a 17-inch diameter right circular cylinder. The fiber orientation angle varies continuously from 10 degrees (with respect to the shell axis of revolution) at the crown, to 45 degrees on the side, and back to 10 degrees on the keel. All 24 tows are placed at each point on every fiber path in one structure designated as the shell with overlaps. The resulting pattern of tow overlaps causes the laminate thickness to vary between 8 and 16 plies. The second shell without tow overlaps uses the capability of the fiber placement machine to cut and add tows at any point along the fiber paths to fabricate a shell with a nearly uniform 8-ply laminate thickness. Issues encountered during the design and analysis of these shells are presented and discussed. Static stiffness and buckling loads of shells with tow-steered layups are compared with the performance of a baseline quasi-isotropic shell using both finite element analyses and classical strength of materials theory.

  10. Eclipse project closeup of QF-106 under tow on takeoff on first flight December 20, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    OFF THE GROUND - The Kelly Space & Technology (KST)/USAF/NASA Eclipse project's modified QF-106 lifts off under tow on the project's first tethered flight on December 20, 1997. The successful 18-minute-long flight reached an altitude of 10,000 feet. NASA's Dryden Flight Research Center, Edwards, California, hosted the project, providing engineering and facility support as well as the project pilot. In 1997 and 1998, the Dryden Flight Research Center at Edwards, California, supported and hosted a Kelly Space & Technology, Inc. project called Eclipse, which sought to demonstrate the feasibility of a reusable tow-launch vehicle concept. The project goal was to successfully tow, inflight, a modified QF-106 delta-wing aircraft with an Air Force C-141A transport aircraft. This would demonstrate the possibility of towing and launching an actual launch vehicle from behind a tow plane. Dryden was the responsible test organization and had flight safety responsibility for the Eclipse project. Dryden provided engineering, instrumentation, simulation, modification, maintenance, range support, and research pilots for the test program. The Air Force Flight Test Center (AFFTC), Edwards, California, supplied the C-141A transport aircraft and crew and configured the aircraft as needed for the tests. The AFFTC also provided the concept and detail design and analysis as well as hardware for the tow system and QF-106 modifications. Dryden performed the modifications to convert the QF-106 drone into the piloted EXD-01 (Eclipse eXperimental Demonstrator-01) experimental aircraft. Kelly Space & Technology hoped to use the results gleaned from the tow test in developing a series of low-cost, reusable launch vehicles. These tests demonstrated the validity of towing a delta-wing aircraft having high wing loading, validated the tow simulation model, and demonstrated various operational procedures, such as ground processing of in-flight maneuvers and emergency abort scenarios.

  11. Eclipse project closeup of QF-106 under tow on first tethered flight December 20, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Kelly Space and Technology (KST)/USAF/NASA Eclipse project's modified QF-106 is shown under tow on the project's first tethered flight on December 20, 1997. The successful 18-minute-long flight reached an altitude of 10,000 feet. NASA's Dryden Flight Research Center, Edwards, California, is hosting the project, providing engineering and facility support as well as the project pilot, Mark Stucky. In 1997 and 1998, the Dryden Flight Research Center at Edwards, California, supported and hosted a Kelly Space & Technology, Inc. project called Eclipse, which sought to demonstrate the feasibility of a reusable tow-launch vehicle concept. The project goal was to successfully tow, inflight, a modified QF-106 delta-wing aircraft with an Air Force C-141A transport aircraft. This would demonstrate the possibility of towing and launching an actual launch vehicle from behind a tow plane. Dryden was the responsible test organization and had flight safety responsibility for the Eclipse project. Dryden provided engineering, instrumentation, simulation, modification, maintenance, range support, and research pilots for the test program. The Air Force Flight Test Center (AFFTC), Edwards, California, supplied the C-141A transport aircraft and crew and configured the aircraft as needed for the tests. The AFFTC also provided the concept and detail design and analysis as well as hardware for the tow system and QF-106 modifications. Dryden performed the modifications to convert the QF-106 drone into the piloted EXD-01 (Eclipse eXperimental Demonstrator-01) experimental aircraft. Kelly Space & Technology hoped to use the results gleaned from the tow test in developing a series of low-cost, reusable launch vehicles. These tests demonstrated the validity of towing a delta-wing aircraft having high wing loading, validated the tow simulation model, and demonstrated various operational procedures, such as ground processing of in-flight maneuvers and emergency abort scenarios.

  12. All-electrical magnetic vortex array sensing

    NASA Astrophysics Data System (ADS)

    Tannous, C.; Gieraltowski, J.

    2016-08-01

    Vortex sensing magnetometers based on arrays of soft magnetic dots are good candidates for high-resolution and accurate spatial magnetic-field estimation. When the arrays are laid out along different spatial directions they can perform tensor gradiometry allowing the measurement of field components and their spatial derivatives as a function of orientation. Detection is based on using spin-polarized currents to counteract vortex displacements or to excite vortex oscillation modes triggered by magnetic-field application. Sensor linearization, field detection range and conditions to obtain large sensitivity electronic compatibility and scalability are discussed.

  13. Horizontal ichthyoplankton tow-net system with unobstructed net opening

    USGS Publications Warehouse

    Nester, Robert T.

    1987-01-01

    The larval fish sampler described here consists of a modified bridle, frame, and net system with an obstruction-free net opening and is small enough for use on boats 10 m or less in length. The tow net features a square net frame attached to a 0.5-m-diameter cylinder-on-cone plankton net with a bridle designed to eliminate all obstructions forward of the net opening, significantly reducing currents and vibrations in the water directly preceding the net. This system was effective in collecting larvae representing more than 25 species of fish at sampling depths ranging from surface to 10 m and could easily be used at greater depths.

  14. Surface towed electromagnetic system for mapping of subsea Arctic permafrost

    NASA Astrophysics Data System (ADS)

    Sherman, Dallas; Kannberg, Peter; Constable, Steven

    2017-02-01

    Sea level has risen globally since the late Pleistocene, resulting in permafrost-bearing coastal zones in the Arctic being submerged and subjected to temperature induced degradation. Knowing the extent of permafrost and how it changes over time is important for climate change predictions and for planning engineering activities in the Arctic environment. We developed a controlled source electromagnetic (CSEM) method to obtain information on the depth, thickness, and lateral extent of marine permafrost. To operate in shallow water we used a surface towed electric dipole-dipole CSEM system suitable for deployment from small boats. This system was used to map permafrost on the Arctic shelf offshore Prudhoe Bay, Alaska. Our results show significant lateral variability in the presence of permafrost, with the thickest layers associated with a large river outflow where freshwater influx seems to have a preserving effect on relict subsea permafrost.

  15. The analysis and system design for MCG measurement based on optically pumped cesium magnetometer

    NASA Astrophysics Data System (ADS)

    Yang, Zhang; Chong, Kang; Wang, Qingtao; Lei, Cheng; Zheng, Caiping

    2010-11-01

    At present, laser optical pumping magnetometer of sensitivity is continuous improved and can measure the range from Earth magnetic field to the bio-magnetic field. In the bio-magnetic field, magnetocardiography (MCG) is paid also more and more attention. In this paper, we will discuss cesium optically pumped magnetometer theoretical analysis, system design, the magnetic field gradient measuring principle. On this basis, we build optically pumped magnetometer in a gradient structure for the cardiac magnetic measurements and filter through the wavelet transform. Based on optical pumping magnetometer measuring MCG will be applied in life science, clinical medicine and other fields.

  16. Opportunity Science Using the Juno Magnetometer Investigation Star Trackers

    NASA Astrophysics Data System (ADS)

    Joergensen, J. L.; Connerney, J. E.; Bang, A. M.; Denver, T.; Oliversen, R. J.; Benn, M.; Lawton, P.

    2013-12-01

    The magnetometer experiment onboard Juno is equipped with four non-magnetic star tracker camera heads, two of which reside on each of the magnetometer sensor optical benches. These are located 10 and 12 m from the spacecraft body at the end of one of the three solar panel wings. The star tracker, collectively referred to as the Advanced Stellar Compass (ASC), provides high accuracy attitude information for the magnetometer sensors throughout science operations. The star tracker camera heads are pointed +/- 13 deg off the spin vector, in the anti-sun direction, imaging a 13 x 20 deg field of view every ¼ second as Juno rotates at 1 or 2 rpm. The ASC is a fully autonomous star tracker, producing a time series of attitude quaternions for each camera head, utilizing a suite of internal support functions. These include imaging capabilities, autonomous object tracking, automatic dark-sky monitoring, and related capabilities; these internal functions may be accessed via telecommand. During Juno's cruise phase, this capability can be tapped to provide unique science and engineering data available along the Juno trajectory. We present a few examples of the JUNO ASC opportunity science here. As the Juno spacecraft approached the Earth-Moon system for the close encounter with the Earth on October 9, 2013, one of the ASC camera heads obtained imagery of the Earth-Moon system while the other three remained in full science (attitude determination) operation. This enabled the first movie of the Earth and Moon obtained by a spacecraft flying past the Earth in gravity assist. We also use the many artificial satellites in orbit about the Earth as calibration targets for the autonomous asteroid detection system inherent to the ASC autonomous star tracker. We shall also profile the zodiacal dust disk, using the interstellar image data, and present the outlook for small asteroid body detection and distribution being performed during Juno's passage from Earth flyby to Jovian orbit

  17. High-Tc SQUID Magnetometers for Industrial Applications

    NASA Astrophysics Data System (ADS)

    Diiorio, Mark; Yang, Kai-Yueh; Yoshizumi, Shozo; Haupt, Steven; Haran, Don; Koch, Roger; Lathrop, Dan; Trammel, Hoke

    1998-03-01

    We have developed high-Tc SQUID magnetometers for use in a variety of industrial applications. Relatively inexpensive direct-coupled magnetometers have been developed for low-frequency applications including fetal-magnetocardiography. A manufacturable process has been developed to reproducibly fabricate high-resistance (up to 6 Ω) SNS step-edge junctions with YBa_2Cu_3O_7-x as the superconductor and Ag-Au alloy as the normal metal. Magnetic field sensitivities at 77K of 22 ft/Hz^1/2 at 1 KHz and 32 ft/Hz^1/2 at 1 Hz have been achieved in a well-shielded laboratory environment. Current effort is focused on operation in an unshielded environment using flux dams(Milliken et al. Appl. Phys. Lett. 71 1857 (1997)) in conjunction with narrow superconducting pickup coils placed in parallel. An integrated magnetometer process has also been optimized for use in high-frequency applications. The integrated megnetometer utilizes two layers of YBa_2Cu_3O_7-x and one layer of deposited SrTiO_3, all on the same 24 mm x 5 mm substrate. The applications under development include the detection of the explosive material in non-metallic land mines using nuclear quadrupole resonance as well as the non-destructive evaluation of non-metallic composites using nuclear magnetic resonance. For operation in the MHz regime, these applications demand a high quality insulator layer and a robust SQUID that can withstand high current transients.

  18. Russian auroral and polar ionospheric disturbance magnetometers (RapidMag)

    NASA Astrophysics Data System (ADS)

    Takahashi, K.; Meng, C. I.; Barnes, R. J.; Zetzer, J.; Troshichev, O.; Janzhura, A.; Kunitake, M.; Watari, S.; Iyemori, T.; Nosé, M.; Keiling, A.; Angelopoulos, V.

    2007-12-01

    Since their introduction by Davis and Sugiura in 1966, the auroral electrojet indices AE, AU, and AL have been widely used to study ionospheric and magnetospheric phenomena associated with substorms as well as input to magnetospheric and ionospheric models. While rapid delivery of the indices is highly desirable in the context of both ongoing scientific observations and space weather applications, production of near-real-time AE indices remains a difficult task. A major challenge is acquisition of near-real-time magnetometer data from Russian auroral zone stations, some of which are at remote locations with harsh natural environment and without well- established infrastructure for data transmission. The stations cover approximately 6 time zones, and missing data from the stations means a serious degradation of the AE indices. The Russian auroral and polar ionospheric disturbance Magnetometer (RapidMag) project is an international collaboration to enable rapid and stable acquisition of ground magnetometer data from Russian stations in the auroral zone for production of near- real-time AE indices as well as for distribution of data from individual stations to the science community. The six RapidMag stations are Amderma (65.1N, 138.1E, degrees, geomagnetic), Dikson Island (68.5N, 156.2E), Norilsk (64.6N, 161.9E), Cape Chelyuskin (71.8N, 175.6E), Tixie (65.9°N, 196.9°E), and Pebek (65.3°N, 228.8E). The RapidMag project is entering a new phase with recent funding from NSF and NASA. We present the current status of the project and our plan for the next 5 years.

  19. Detection and Discrimination in One-Pass Using the OPTEMA Towed-Array

    DTIC Science & Technology

    2014-11-01

    classification quality data during dynamic Electromagnetic Induction (EMI) surveys of Munitions Response Sites (MRS). The process of obtaining both...response, Electromagnetic induction 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE... Electromagnetic Induction FPR – False Positive Rejection IVS – Instrument Verification Strip MEC – Munitions and Explosives of Concern MLE – Mean Location Error

  20. Data Processing Requirement for a Deep Towed Multi-Channel Array.

    DTIC Science & Technology

    1979-09-26

    over 4 years, a simple linear amortization plus a 12% of initial capital annual J] rate for service and maintance indicates a cost of less that $9/km...for this system:I Capital cost /year * $1.6500 Service and Maintance + 7,920 J Total ainual system cost $24,420 Assuming 2x1480 km are processed

  1. Demonstration of the Marine Towed Array on Bahia Salinas del Sur Vieques, Puerto Rico

    DTIC Science & Technology

    2009-02-01

    3.892 -69 273 0.095 cable or steel pole , note depth 125 1229.36 1603.36 256229.36 2005603.36 8.09 -33 16 0.18 0.214 3.894 -2 351 0.945 mostly remnant...Cell: 919-522-8029 Email: gibsonc@saic.com SAIC 209 W. Vine St...554.50 2166.09 255554.50 2006166.09 1.02 -4291.8 5552.2 1.12 1.36 1006.3 16 17 0.936 Massive chunk of steel at the shoreline in very shallow wate 8

  2. Airborne UXO Surveys Using the Multi-Sensor Towed Array Detection System (MTADS)

    DTIC Science & Technology

    2005-07-01

    position update (at 20 Hz) with an accuracy in the horizontal plane of about 5 cm. GPS satellite clock time is used to time-stamp both position and...FBO fixed base operator FUDS former used defense sites GIS geographic information system GP general purpose GPS Global Positioning System...operation on all models of the Bell Long Ranger helicopter. Two global positioning system ( GPS ) units mounted on the forward boom provide

  3. Wear Test Results of Candidate Materials for the OK-542 Towed Array Handling Machine Level Winder

    DTIC Science & Technology

    1994-12-29

    were being considered. Unfortunately, these other options, which included thermal spraying , carbide inserts and wear coatings required long lead...applications. these include various wear-resistant coatings, thermal spraying , and the use of special inserts. 4 TM941159 Based on the testing and

  4. A Steady-State and Hydroelastic Analysis of Towed Line Arrays for ASW target Applications

    DTIC Science & Technology

    1983-02-01

    ETA) GRZ (ICI) )=S RZ(I END) -SRZ (K)I EX=CRX(ICI)-XX EY=CRY(IC1)-YY EZ=CRZ(ICI)-ZZ 1RDPH=ATAN (-EZ/EX) RDKIT =ATAN (EY/EX) CDPH(IC)=RDPH*57. 296I...CDKITE(IC)-IDKIT*S7. 296 IF(IC.GT.1) GO TO 1702 RR=-SQRT (EX*EX+EY*EY)3 BETA=ATAN(EZ/RR) CTXX(IC)--CT(IC)*COS(BETA)*COS( RDKIT ) CTYY(IC)--CT(IC)*COS(BETA...SIN( RDKIT ) GTZZ (IC)-CT( IC)*SIN (BETA)I 1702 CONTINUTE GO TO 907 1700 EX=XDIF-XX EZ=SRZ(IEND)-CRZ(IC) RDPH=ATAN (-EZ/EX) RDKITT=ATAN (EY/EX) A-16 I

  5. Low-Frequency Reverberation Measurements with an Activated Towed Array: Scattering Strengths and Statistics,

    DTIC Science & Technology

    1987-10-01

    Mediterranean Abyssal Plains and features a rather homogeneous seafloor structure. A description of the geophysical and geological characteristics of the basin...introduced in the dynamical equations of propagation. The me- dium itself is treated as infinite and everywhre homogeneous and isotropic. First order... eigenrays is given by I,, = P.D. us, do% D,, (12) where P is the source power; [r,_ is the received intensity; D. is the source direc- tional gain in the

  6. Detection of UXO in Underwater Sites Using Towed Array Resistivity/IP Measurements

    DTIC Science & Technology

    2004-03-10

    for a very successful method of mineral exploration . It is well known, however, that IP responses are also associated with buried metallic culture (e.g...fences, well casing, pipes, and culverts). In mineral exploration , this "cultural noise" is to be avoided. In the context of the detection of UXO

  7. 33 CFR 164.74 - Towline and terminal gear for towing astern.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... intended service; (iii) Appropriate for the sea conditions expected during the intended service; (iv... abrasion or chafing by chafing gear, lagging, or other means; (6) Except on board a vessel towing in ice...

  8. 33 CFR 164.74 - Towline and terminal gear for towing astern.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... intended service; (iii) Appropriate for the sea conditions expected during the intended service; (iv... abrasion or chafing by chafing gear, lagging, or other means; (6) Except on board a vessel towing in ice...

  9. Mechanical characterization of two thermoplastic composites fabricated by automated tow placement

    NASA Technical Reports Server (NTRS)

    Dickinson, Larry C.; Deaton, Jerry W.

    1993-01-01

    AS4/PEEK towpreg and IM7/Radel 8320 slit tape were used to make flat panels by automated tow placement. The panels were tested in notched and un-notched tension, notched and un-notched compression and compression after impact (CAI) at room temperature and under hot/wet conditions (notched and un-notched compression and CAI only). The properties were compared with AS4/PEEK tape laminate properties found in the literature. The tow placed AS4/PEEK material was stronger in tension but weaker in compression than the AS4/PEEK tape laminates. The tow placed AS4/PEEK was stronger but less stiff than the tow placed IM7/Radel 8320 in all compression tests. The IM7/Radel performed better in all other mechanical tests. The IM7/Radel outperformed the AS4/PEEK in all CAI tests.

  10. High resolution polar Kerr magnetometer for nanomagnetism and nanospintronics.

    PubMed

    Cormier, M; Ferré, J; Mougin, A; Cromières, J-P; Klein, V

    2008-03-01

    A new high resolution polar magneto-optical (MO) Kerr magnetometer, devoted to the study of nanometer sized elements with perpendicular magnetic anisotropy, is described. The unique performances of this setup in terms of sensitivity (1.2x10(-15) emu), stability (lateral drift +/-35 nm over 3 h), and resolution (laser spot full width at half maximum down to 470 nm) are demonstrated, and illustrated by Kerr hysteresis loop measurements on a unique ultrathin magnetic nanodot, and over small segments of ultranarrow magnetic tracks. Large scanning MO Kerr microscopy images were also obtained with the same performances.

  11. Magnetometer-Only Attitude and Rate Estimates for Spinning Spacecraft

    NASA Technical Reports Server (NTRS)

    Challa, M.; Natanson, G.; Ottenstein, N.

    2000-01-01

    A deterministic algorithm and a Kalman filter for gyroless spacecraft are used independently to estimate the three-axis attitude and rates of rapidly spinning spacecraft using only magnetometer data. In-flight data from the Wide-Field Infrared Explorer (WIRE) during its tumble, and the Fast Auroral Snapshot Explorer (FAST) during its nominal mission mode are used to show that the algorithms can successfully estimate the above in spite of the high rates. Results using simulated data are used to illustrate the importance of accurate and frequent data.

  12. Evaluation of the Impact of Towing the L-1011 Airplane at Boston-Logan Airport

    DTIC Science & Technology

    1980-05-01

    Stress analysis of the nose landing gear and back-up structure was performed using the load spectrum representing extended towing at Boston-Logan. The...Dorval testing) T. Blase (Stress analysis ) The Lockheed effort was supervised by J.E. Wignot (Dynamics and Vibration Group) under the management of A.F...design fatigue load spectrum was used as a basepoint for the analysis , with the original towing load spectrum replaced by the spectrum representing

  13. Driven microswimmers on a 2D substrate: A stochastic towed sled model

    SciTech Connect

    Marchegiani, Giampiero; Marchesoni, Fabio

    2015-11-14

    We investigate, both numerically and analytically, the diffusion properties of a stochastic sled sliding on a substrate, subject to a constant towing force. The problem is motivated by the growing interest in controlling transport of artificial microswimmers in 2D geometries at low Reynolds numbers. We simulated both symmetric and asymmetric towed sleds. Remarkable properties of their mobilities and diffusion constants include sidewise drifts and excess diffusion peaks. We interpret our numerical findings by making use of stochastic approximation techniques.

  14. Towing of sensory axons by their migrating target cells in vivo.

    PubMed

    Gilmour, Darren; Knaut, Holger; Maischein, Hans-Martin; Nüsslein-Volhard, Christiane

    2004-05-01

    Many pathfinding axons must locate target fields that are themselves positioned by active migration. A hypothetical method for ensuring that these migrations are coordinated is towing, whereby the extension of axons is entirely dependent on the migration of their target cells. Here we combine genetics and time-lapse imaging in the zebrafish to show that towing by migrating cells is a bona fide mechanism for guiding pathfinding axons in vivo.

  15. A Physics-based Automated Technique for the Detection of Field Line Resonance Frequency in Ground Magnetometer Data

    NASA Astrophysics Data System (ADS)

    Boudouridis, A.; Zesta, E.; Moldwin, M.

    2015-12-01

    The accurate determination of the Field Line Resonance (FLR) frequency of a resonating geomagnetic field line is necessary for the remote monitoring of the plasmaspheric mass density during geomagnetic storms and quiet times alike. Under certain assumptions the plasmaspheric mass density at the equator is inversely proportional to the square of the FLR frequency. The most common techniques to determine the FLR frequency from ground magnetometer measurements are the amplitude ratio and phase difference techniques, both based on geomagnetic field measurements at two latitudinally separated ground stations. Previously developed automated techniques have used statistical methods to pinpoint the FLR frequency using the amplitude ratio and phase difference calculations. We now introduce a physics-based automated technique that can reproduce the resonant wave characteristics from the two ground station data, and from those determine the FLR frequency. The advantage of the new technique, besides moving away from ambiguous statistical manipulations of the ground data, is the estimation of physically determined errors of the FLR frequency, which can yield physically determined errors of the equatorial plasmaspheric mass density. We present preliminary results of the new technique calculations, and test it using data from the new Inner-Magnetospheric Array for Geospace Science (iMAGS) ground magnetometer chain along the coast of Chile and the east coast of the United States. We compare the results with the results of previously published statistical automated techniques.

  16. Deep Water Munitions Detection System

    DTIC Science & Technology

    2010-03-01

    UXO unexploded ordnance GPS global positioning system MTA marine towed array TG towed gradiometer Mag magnetic nT nanotesla rms root mean square...other sites were used which had been surveyed with Geometrics Towed Gradiometer (TG) systems. In both of the gradiometer based surveys the data from...the individual magnetometers that made up the gradiometer were available. Magnetic anomalies from each site were reanalyzed to produce uniform target

  17. Recovery of a temperate reef assemblage in a marine protected area following the exclusion of towed demersal fishing.

    PubMed

    Sheehan, Emma V; Stevens, Timothy F; Gall, Sarah C; Cousens, Sophie L; Attrill, Martin J

    2013-01-01

    Marine Protected Areas MPA have been widely used over the last 2 decades to address human impacts on marine habitats within an ecosystem management context. Few studies have quantified recovery of temperate rocky reef communities following the cessation of scallop dredging or demersal trawling. This is critical information for the future management of these habitats to contribute towards conservation and fisheries targets. The Lyme Bay MPA, in south west UK, has excluded towed demersal fishing gear from 206 km(2) of sensitive reef habitat using a Statutory Instrument since July 2008. To assess benthic recovery in this MPA we used a flying video array to survey macro epi-benthos annually from 2008 to 2011. 4 treatments (the New Closure, previously voluntarily Closed Controls and Near or Far Open to fishing Controls) were sampled to test a recovery hypothesis that was defined as 'the New Closure becoming more similar to the Closed Controls and less similar to the Open Controls'. Following the cessation of towed demersal fishing, within three years positive responses were observed for species richness, total abundance, assemblage composition and seven of 13 indicator taxa. Definitive evidence of recovery was noted for species richness and three of the indicator taxa (Pentapora fascialis, Phallusia mammillata and Pecten maximus). While it is hoped that MPAs, which exclude anthropogenic disturbance, will allow functional restoration of goods and services provided by benthic communities, it is an unknown for temperate reef systems. Establishing the likely timescales for restoration is key to future marine management. We demonstrate the early stages of successful recruitment and link these to the potential wider ecosystem benefits including those to commercial fisheries.

  18. Design and Manufacturing of Tow-Steered Composite Shells Using Fiber Placement

    NASA Technical Reports Server (NTRS)

    Wu, K. Chauncey; Tatting, Brian F.; Smith, Brett H.; Stevens, Randy S.; Occhipiniti, Gina P.; Swift, Jonathan B.; Achary, David C.; Thornburgh, Robert P.

    2009-01-01

    Advanced composite shells that may offer the potential to improve the structural performance of future aircraft fuselage structures were developed under this joint NASA-industry collaborative effort. Two cylindrical shells with tailored, tow-steered layups and continuously varying fiber angle orientations were designed and built at the National Center for Advanced Manufacturing - Louisiana Partnership. The shells were fabricated from unidirectional IM7/8552 graphite-epoxy pre-preg slit tape material fiber-placed on a constant-diameter mandrel. Each shell had the same nominal 8-ply [plus or minus 45/plus or minus Theta]s layup, where the nominal fiber angle in the tow-steered plies varied continuously from 10 degrees along the crown to 45 degrees on each side, then back to 10 degrees on the keel. One shell was fabricated with all 24 tows placed during each pass of the fiber placement machine, resulting in many tow overlaps on the shell surface. The fiber placement machine's individual tow cut/restart capability was also used to manufacture a second shell with tow drops and a more uniform laminate thickness. This paper presents an overview of the detailed design and manufacturing processes for these shells, and discusses issues encountered during their fabrication and post-cure evaluation. Future plans for structural testing and analyses of the shells are also discussed.

  19. M2-F1 under tow across lakebed by car

    NASA Technical Reports Server (NTRS)

    1963-01-01

    This 20-second clip shows the M2-F1 being towed by the Pontiac across Rogers Dry Lakebed. The M2-F1 lifting body, dubbed the 'flying bathtub' by the media, was the precursor of a remarkable series of wingless flying vehicles that contributed data used in the Space Shuttles, the X-33 Advanced Technology Demonstrator for the next century's Reusable Launch Vehicle, and the X-38 Technology Demonstrator for crew return from the International Space Station. Based on the ideas and basic design of Alfred J. Eggers and others at the Ames Aeronautical Laboratory (now the Ames Research Center), Mountain View, California, in the mid-1950's, the M2-F1 was built in 1962-63 over a four-month period for a cost of only about $30,000, plus an additional $8,000-$10,000 for an ejection seat. Engineers and technicians at the NASA Flight Research Center (now NASA Dryden) kept costs low by designing and fabricating it partly in-house, with the plywood shell constructed by a local sailplane builder. Someone at the time estimated that it would have cost a major aircraft company $150,000 to build the same vehicle. Unlike the later lifting bodies, the M2-F1 was unpowered and was initially towed by a souped-up Pontiac convertible until it was airborne. Later a C-47 took over the towing duties. Flown by such famous research pilots as Milt Thompson, Bruce Peterson, Chuck Yeager, and Bill Dana, the lightweight flying bathtub demonstrated that a wingless vehicle shaped for reentry into the Earth's atmosphere from space could be flown and landed safely. Flown from 1963 to 1966, the lightweight M2-F1 paved the way for the heavyweight M2-F2, M2`F3, HL-10, X-24A, and X-24B lifting bodies that flew under rocket power after launch from a B-52 mothership. The heavyweights flew from 1966 to 1975, demonstrating the viability and versatility of the wingless configuration and the ability of a vehicle with low lift-over-drag characteristics to fly to high altitudes and then to land precisely with their

  20. Amplitude modulated Lorentz force MEMS magnetometer with picotesla sensitivity

    NASA Astrophysics Data System (ADS)

    Kumar, Varun; Ramezany, Alireza; Mahdavi, Mohammad; Pourkamali, Siavash

    2016-10-01

    This paper demonstrates ultra-high sensitivities for a Lorentz force resonant MEMS magnetometer enabled by internal-thermal piezoresistive vibration amplification. A detailed model of the magneto-thermo-electro-mechanical internal amplification is described and is in good agreement with the experimental results. Internal amplification factors up to ~1620 times have been demonstrated by artificially boosting the effective quality factor of the resonator from 680 to 1.14  ×  106 by tuning the bias current. The increase in the resonator bias current in addition to the improvement in the quality factor of the device led to a sensitivity enhancement by ~2400 times. For a bias current of 7.245 mA, where the effective quality factor of the device and consequently the sensitivity is maximum (2.107 mV nT-1), the noise floor is measured to be as low as 2.8 pT (√Hz)-1. This is by far the most sensitive Lorentz force MEMS magnetometer demonstrated to date.

  1. Lunar electrical conductivity, permeability and temperature from Apollo magnetometer experiments

    NASA Technical Reports Server (NTRS)

    Dyal, P.; Parkin, C. W.; Daily, W. D.

    1977-01-01

    Magnetometers were deployed at four Apollo sites on the moon to measure remanent and induced lunar magnetic fields. Measurements from this network of instruments were used to calculate the electrical conductivity, temperature, magnetic permeability, and iron abundance of the lunar interior. The measured lunar remanent fields range from 3 gammas minimum at the Apollo 15 site to 327 gammas maximum at the Apollo 16 site. Simultaneous magnetic field and solar plasma pressure measurements show that the remanent fields at the Apollo 12 and 16 sites interact with, and are compressed by, the solar wind. Remanent fields at Apollo 12 and Apollo 16 are increased 16 gammas and 32 gammas, respectively, by a solar plasma bulk pressure increase of 1.5 X 10 to the -7th power dynes/sq cm. Global lunar fields due to eddy currents, induced in the lunar interior by magnetic transients, were analyzed to calculate an electrical conductivity profile for the moon. From nightside magnetometer data in the solar wind it was found that deeper than 170 km into the moon the conductivity rises from .0003 mhos/m to .10 mhos/m at 100 km depth. Recent analysis of data obtained in the geomagnetic tail, in regions free of complicating plasma effects, yields results consistent with nightside values.

  2. Effect of mobility devices on orientation sensors that contain magnetometers.

    PubMed

    Kendell, Cynthia; Lemaire, Edward D

    2009-01-01

    Orientation sensors containing magnetometers use the earth's magnetic field as a reference. Ferromagnetic objects may distort this magnetic field, leading to inaccurate orientation output. We explored the viability of these orientation sensors for motion analysis in an assistive mobility device rehabilitative setting. We attached two MTx orientation sensors (XSens; Enschade, the Netherlands), connected to the XBus Master data collection unit (XSens), to a plastic frame such that the relative angle between sensors was constant. We then moved a series of mobility devices in proximity to the plastic frame: two knee-ankle-foot orthoses (aluminum, stainless steel), one ankle-foot orthosis, two transtibial prostheses (exoskeletal, endoskeletal), two walkers (standard, Challenger Low Wide [Evolution Technologies; Port Coquitlam, Canada]), and two wheelchairs (Tango [OrthoFab; Quebec City, Canada], GTi [Quickie; Phoenix, Arizona]). For each mobility device, we calculated the average difference in relative angle between the baseline and peak angles for each of five trials. Errors ranged from less than 0.10 to 35.29 degrees, depending on the mobility device and frame positioning near the device. This demonstrated the large errors that can occur when magnetometer-based orientation sensors with mobility devices are used. While strategic orientation sensor placement on some mobility devices can minimize these errors to an acceptable level, testing protocols should be implemented to verify orientation sensor accuracy for these applications.

  3. High-resolution fully vectorial scanning Kerr magnetometer.

    PubMed

    Flajšman, Lukáš; Urbánek, Michal; Křižáková, Viola; Vaňatka, Marek; Turčan, Igor; Šikola, Tomáš

    2016-05-01

    We report on the development of a high-resolution scanning magnetometer, which fully exploits the vectorial nature of the magneto-optical Kerr effect. The three-dimensional nature of magnetization is at the basis of many micromagnetic phenomena and from these data, we can fully characterize magnetization processes of nanostructures in static and dynamic regimes. Our scanning Kerr magnetometer uses a high numerical aperture microscope objective where the incident light beam can be deterministically deviated from the objective symmetry axis, therefore, both in-plane (via the longitudinal Kerr effect) and out-of-plane (via the polar Kerr effect) components of the magnetization vector may be detected. These components are then separated by exploiting the symmetries of the polar and longitudinal Kerr effects. From four consecutive measurements, we are able to directly obtain the three orthogonal components of the magnetization vector with a resolution of 600 nm. Performance of the apparatus is demonstrated by a measurement of 3D magnetization vector maps showing out-of-plane domains and in-plane domain walls in an yttrium-iron-garnet film and on a study of magnetization reversal in a 4-μm-wide magnetic disk.

  4. DC SQUID RF magnetometer with 200 MHz bandwidth

    NASA Astrophysics Data System (ADS)

    Talanov, Vladimir; Lettsome, Nesco; Orozco, Antonio; Cawthorne, Alfred; Borzenets, Valery

    2012-02-01

    Because of periodic flux-to-voltage transfer function, Superconducting QUantum Interference Device (SQUID) magnetometers operate in a closed-loop regime [1], which linearizes the response, and increases the dynamic range and sensitivity. However, a transmission line delay between the SQUID and electronics fundamentally limits the closed-loop bandwidth at 20 MHz [1], although the intrinsic bandwidth of SQUIDs is in gigahertz range. We designed a DC SQUID based RF magnetometer capable of wideband sensing coherent magnetic fields up to 200 MHz. To overcome the closed-loop bandwidth limitation, we utilized a low-frequency flux-modulated closed-loop to simultaneously lock the quasi-static magnetic flux and provide AC bias for the RF flux. The SQUID RF voltage is processed by RF electronics based on a double lock-in technique. This yields a signal proportional to the amplitude and phase of the RF magnetic flux, with more than four decades of a linear response. For YBaCuO SQUID on bi-crystal SrTiO substrate at 77 K we achieved a flux noise density of 4 μφ0/Hz at 190 MHz, which is similar to that measured at kHz frequencies with conventional flux-locked loop. [1] D. Drung, et al., Supercond. Sci. Technol. 19, S235 (2006).

  5. Ring-core fluxgate magnetometers for use as observatory variometers

    NASA Astrophysics Data System (ADS)

    Narod, B. B.; Bennest, J. R.

    Ring-core magnetometers, based on the published design for the MAGSAT fluxgate magnetometer, are or will soon be in use in observatories in the U.S.A. and in Canada. Their low noise level and good stability with both temperature and time make them well suited for this purpose. We describe the critical performance features and design aspects for these instruments. Noise in all ring-core magnetometers has approximately a 1/frequency response in power spectral density. The principal source of the noise is from the ring-cores themselves. In the best instruments, which use a d.c. bias supply to enhance dynamic range, noise from the voltage reference used in the bias supply can approach significant levels at large offset values (˜ 60 000 nT). In these instruments noise in the 0.001-100 Hz band is typically less than 0.1 nT amplitude, and reduces accordingly with reduced bandwidth. Good thermal stability for the sensor is achieved by matching thermal expansion coefficients of all the sensor materials, and by compensating thermal expansion of the sensor with an increase in feedback current. Changes in the sensor-winding resistances provide the cues for the compensation circuitry. In settings where long cables separate the sensor from its electronics, platinum resistance elements included with the sensor winding can ensure that variations in cable resistance will not significantly affect the temperature compensation. Thermal stability of 0.1 nT deg -1 are typically achievable for the sensor. Thermal stability for the electronic components depends primarily on the stability of the d.c. bias supply. These can be designed for a stability of 3 ppm deg -1, which translates to 0.2 nT deg -1 for a field of 60 000 nT. Long-term drift results primarily from the aging of the sensor winding and the d.c. bias supply components Engineering data for the best available components suggest that drift of less than 50 ppm yr -1 is possible. This translates to 3 nT yr -1 in a 60 000 nT field

  6. Hodograph method to estimate the latitudinal profile of the field-line resonance frequency using the data from two ground magnetometers

    NASA Astrophysics Data System (ADS)

    Pilipenko, V. A.; Kawano, H.; Mann, I. R.

    2013-05-01

    The hodograph method enables estimating the latitudinal profile of the field-line resonance (FLR) frequency ( f R ) using the data from two ground magnetometers. This paper provides the full details of this method for the first time, and uses a latitudinal chain of ground magnetometers to examine its validity and usefulness. The hodograph method merges the widely-used amplitude-ratio and cross-phase methods in a sense that the hodograph method uses both the amplitude ratio and the phase difference in a unified manner; further than that, the hodograph method provides f R at any latitude near those of the two ground magnetometers. It is accomplished by (1) making a complex number by using the amplitude ratio (phase difference) as its real (imaginary) part; (2) drawing thus obtained complex numbers (one number for one frequency) in the complex plane to make a hodograph; and (3) fitting to thus obtained hodograph a model satisfying the FLR condition, which is a circle with the assumption that the resonance width is independent of the latitude. To examine the validity and usefulness of the hodograph method, we apply it to a Pc 4 event observed by the Scandinavian BEAR array. We also apply the amplitude-phase gradient method (Pilipenko and Fedorov, 1994; Kawano et al., 2002) to the same event, and compare the results; this is the first article applying the both methods to the same dataset.

  7. Electromagnetic imaging with atomic magnetometers: a novel approach to security and surveillance

    NASA Astrophysics Data System (ADS)

    Hussain, Sarah; Marmugi, Luca; Deans, Cameron; Renzoni, Ferruccio

    2016-05-01

    We describe our research programme on the use of atomic magnetometers to detect conductive objects via electromagnetic induction. The extreme sensitivity of atomic magnetometers at low frequencies, up to seven orders of magnitude higher than a coil-based system, permits deep penetration through different media and barriers, and in various operative environments. This eliminates the limitations usually associated with electromagnetic detection.

  8. Full Scale Wind Tunnel and Seaplane Tow Channel

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Construction progress, Full Scale exit cone looking south from entrance cone, east switchboard, west switchboard, wind vanes at north end looking north through entrance cone, north end looking south through entrance cone, entrance cone looking north from exit cone, wind vanes south end of west exit cone, wind vanes south end of east exit cone, Tow Channel trolley lines looking north, east and west incline braces at north end. Full-Scale Tunnel (FST) exit cone construction and installation of fan motors. Smith DeFrance describes the entrance cone in NACA TR 459 as follows: 'Forward of the propellers and located on the center line of the tunnel is a smooth fairing which transforms the somewhat elliptic section of the single passage into two circular ones at the propellers. From the propellers aft, the exit cone is divided into two passages and each transforms in the length of 132 feet from a 35-foot 61/2-inch circular section to a 46-foot square. The included angle between the sides of each passage is 6 inches.' (p. 293)

  9. Design and Manufacture of Elastically Tailored Tow Placed Plates

    NASA Technical Reports Server (NTRS)

    Tatting, Brain F.; Guerdal, Zafer; Jegley, Dawn (Technical Monitor)

    2002-01-01

    Elastic stiffness tailoring of laminated composite panels by allowing the fibers to curve within the plane of the laminate is a relatively novel design concept that has been demonstrated to be both beneficial and practical. In particular, for structures with highly non-uniform stress states, such as the case of a flat panel with a central hole subjected to in-plane loading, the concept is likely to provide substantial improvements in load carrying capability. The objective of the present study is to determine the effectiveness of stiffness tailoring through the use of curvilinear fibers to reduce stress concentrations around the hole and improve the load carrying capability of panels with holes. In this study software was created that translates standard finite element models with traditional laminate definitions into ones that possess stacking sequences with curvilinear fiber paths that are directly manufacturable using an advanced tow placement machine. Preliminary designs for the manufacturing and testing phase were determined through rudimentary design studies for flat plates without holes under axial compression. These candidate designs were then analyzed using finite element models that accurately reflect the test conditions and geometries in order to select final designs for testing. A total of six large panels, measuring three feet by six feet, each of which are used to produce four specimens with or without holes, were fabricated and delivered to NASA for machining and testing.

  10. Response of automated tow placed laminates to stress concentrations

    NASA Technical Reports Server (NTRS)

    Cairns, Douglas S.; Ilcewicz, Larry B.; Walker, Tom

    1993-01-01

    In this study, the response of laminates with stress concentrations is explored. Automated Tow Placed (ATP, also known as Fiber Placement) laminates are compared to conventional tape layup manufacturing. Previous tensile fracture tests on fiber placed laminates show an improvement in tensile fracture of large notches over 20 percent compared to tape layup laminates. A hierarchial modeling scheme is presented. In this scheme, a global model is developed for laminates with notches. A local model is developed to study the influence of inhomogeneities at the notch tip, which are a consequence of the fiber placement manufacturing technique. In addition, a stacked membrane model was developed to study delaminations and splitting on a ply-by-ply basis. The results indicate that some benefit with respect to tensile fracture (up to 11 percent) can be gained from inhomogeneity alone, but that the most improvement may be obtained with splitting and delaminations which are more severe in the case of fiber placement compared to tape layup. Improvements up to 36 percent were found from the model for fiber placed laminates with damage at the notch tip compared to conventional tape layup.

  11. Preliminary analysis of the Hellenic geomagnetic array stations' response functions

    NASA Astrophysics Data System (ADS)

    di Fiore, B.; Balasis, G.; Kapiris, P.; Daglis, I. A.; Ganas, A.; Melis, N.

    2009-04-01

    The National Observatory of Athens currently operates the HellENIc GeoMagnetic Array (ENIGMA), an array of 4 ground-based magnetometer stations in the area of south-eastern Europe (central and southern Greece). Based on one year (2008) of vector magnetic field data, recorded at the various array sites, magnetic response function estimates are inferred at 5 s - 2048 s. The magnetic response functions are then viewed as real and imaginary induction arrows, detecting sharp conductivity boundaries and providing a picture of the geometry of regional conductors. First results from efforts on inversion and modelling of the ENIGMA magnetic response functions will also be discussed.

  12. Magnetic arrays

    SciTech Connect

    Trumper, David L.; Kim, Won-jong; Williams, Mark E.

    1997-05-20

    Electromagnet arrays which can provide selected field patterns in either two or three dimensions, and in particular, which can provide single-sided field patterns in two or three dimensions. These features are achieved by providing arrays which have current densities that vary in the windings both parallel to the array and in the direction of array thickness.

  13. Magnetic arrays

    DOEpatents

    Trumper, D.L.; Kim, W.; Williams, M.E.

    1997-05-20

    Electromagnet arrays are disclosed which can provide selected field patterns in either two or three dimensions, and in particular, which can provide single-sided field patterns in two or three dimensions. These features are achieved by providing arrays which have current densities that vary in the windings both parallel to the array and in the direction of array thickness. 12 figs.

  14. Swarm Absolute Scalar Magnetometers first in-orbit results

    NASA Astrophysics Data System (ADS)

    Fratter, Isabelle; Léger, Jean-Michel; Bertrand, François; Jager, Thomas; Hulot, Gauthier; Brocco, Laura; Vigneron, Pierre

    2016-04-01

    The ESA Swarm mission will provide the best ever survey of the Earth's magnetic field and its temporal evolution. This will be achieved by a constellation of three identical satellites, launched together on the 22nd of November 2013. In order to observe the magnetic field thoroughly, each satellite carries two magnetometers: a Vector Field Magnetometer (VFM) coupled with a star tracker camera, to measure the direction of the magnetic field in space, and an Absolute Scalar Magnetometer (ASM), to measure its intensity. The ASM is the French contribution to the Swarm mission. This new generation instrument was designed by CEA-Leti and developed in close partnership with CNES, with scientific support from IPGP. Its operating principle is based on the atomic spectroscopy of the helium 4 metastable state. It makes use of the Zeeman's effect to transduce the magnetic field into a frequency, the signal being amplified by optical pumping. The primary role of the ASM is to provide absolute measurements of the magnetic field's strength at 1 Hz, for the in-flight calibration of the VFM. As the Swarm magnetic reference, the ASM scalar performance is crucial for the mission's success. Thanks to its innovative design, the ASM offers the best precision, resolution and absolute accuracy ever attained in space, with similar performance all along the orbit. In addition, thanks to an original architecture, the ASM implements on an experimental basis a capacity for providing simultaneously vector measurements at 1 Hz. This new feature makes it the first instrument capable of delivering both scalar and vector measurements simultaneously at the same point. Swarm offers a unique opportunity to validate the ASM vector data in orbit by comparison with the VFM's. Furthermore, the ASM can provide scalar data at a much higher sampling rate, when run in "burst" mode at 250 Hz, with a 100 Hz measurement bandwidth. An analysis of the spectral content of the magnetic field above 1 Hz becomes thus

  15. Low energy electron magnetometer using a monoenergetic electron beam

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Wood, G. M.; Rayborn, G. H.; White, F. A. (Inventor)

    1983-01-01

    A low energy electron beam magnetometer utilizes near-monoenergetic electrons thereby reducing errors due to electron energy spread and electron nonuniform angular distribution. In a first embodiment, atoms in an atomic beam of an inert gas are excited to a Rydberg state and then electrons of near zero energy are detached from the Rydberg atoms. The near zero energy electrons are then accelerated by an electric field V(acc) to form the electron beam. In a second embodiment, a filament emits electrons into an electrostatic analyzer which selects electrons at a predetermined energy level within a very narrow range. These selected electrons make up the electron beam that is subjected to the magnetic field being measured.

  16. Magnetoencephalography with a chip-scale atomic magnetometer

    PubMed Central

    Sander, T. H.; Preusser, J.; Mhaskar, R.; Kitching, J.; Trahms, L.; Knappe, S.

    2012-01-01

    We report on the measurement of somatosensory-evoked and spontaneous magnetoencephalography (MEG) signals with a chip-scale atomic magnetometer (CSAM) based on optical spectroscopy of alkali atoms. The uncooled, fiber-coupled CSAM has a sensitive volume of 0.77 mm3 inside a sensor head of volume 1 cm3 and enabled convenient handling, similar to an electroencephalography (EEG) electrode. When positioned over O1 of a healthy human subject, α-oscillations were observed in the component of the magnetic field perpendicular to the scalp surface. Furthermore, by stimulation at the right wrist of the subject, somatosensory-evoked fields were measured with the sensors placed over C3. Higher noise levels of the CSAM were partly compensated by higher signal amplitudes due to the shorter distance between CSAM and scalp. PMID:22567591

  17. Plasmasphere Refilling After Geomagnetic Storms Observed by EMMA Magnetometer Network

    NASA Astrophysics Data System (ADS)

    Del Corpo, A.; Vellante, M.; Heilig, B.; Lichtenberger, J.; Reda, J.; Pietropaolo, E.; Chi, P. J.

    2015-12-01

    We present the results of a study of plasmasphere dynamics during a few geomagnetic storms through examination of radial profiles of the equatorial plasma mass density. The plasma mass density is derived from field line resonance (FLR) frequencies observations across EMMA, a meridional network of 25 magnetometer stations extending from Central Italy to North Finland (1.5 < L < 6.5). The study focuses on plasmaspheric refilling following depletion due to geomagnetic activity. From the time variation of the equatorial plasma mass density we derived daytime refilling rates and the corresponding upward plasma fluxes from the ionosphere for different L-values. Daily averaged refilling rates occurring during the recovery phase have been also investigated.

  18. Measurement of Lung Function Using the Magnetometer System.

    DTIC Science & Technology

    1983-07-01

    8217 NORMALIZED AMPLITUDES’ 280 PRINT 300 PRINT ’SPIROMETER MAGi MAG2 MAG3 MAG4’ 310 G1:G(0,1) 320 FOR J=1 TO N2 341 PRINT G(O,J)/G1,G(1,J)/G(1,1),G(2,J...ANGLES’ 420 PRINT 440 PRINT ’SPIROMETER MAG1 MAG2 MAG3 MAG41 450 P1=PI/2 455 N5=P1-P(0,1) 460 FOR J=1 TO N2 481 PRINT P(O,J)+N5,P(1 ,J)+N5,P(2,J)+N5,P...MAGNETOMETER DATA ** ZOO PRINT #S,- ZZ0 PRINT #5,’ NORMALIZED AMPLITUDES’ 240 PRINT #5," 260 PRINT #5,’SPIROMETER MAGI MAGZ MAG3 MAG4’ Z70 G1-G(0,I

  19. Benchtop time-resolved magneto-optical Kerr magnetometer.

    PubMed

    Barman, Anjan; Kimura, T; Otani, Y; Fukuma, Y; Akahane, K; Meguro, S

    2008-12-01

    We present here the construction and application of a compact benchtop time-resolved Kerr magnetometer to measure the magnetization precession in magnetic thin films and lithographically patterned elements. As opposed to very expensive femtosecond lasers this system is built upon a picosecond pulsed injection diode laser and electronic pulse and delay generators. The precession is triggered by the electronic pulses of controlled duration and shape, which is launched onto the sample by a microstrip line. We used polarized optical pulses synchronous to the electronic pulses to measure the magneto-optical Kerr rotation. The system is integrated in a conventional upright microscope configuration with separate illumination, imaging, and magneto-optical probe paths. The system offers high stability, relative ease of alignment, sample changing, and a long range of time delay. We demonstrate the measurements of time-resolved dynamics of a Permalloy microwire and microdot using this system, which showed dynamics at two different time scales.

  20. Magnetometer-augmented IMU simulator: in-depth elaboration.

    PubMed

    Brunner, Thomas; Lauffenburger, Jean-Philippe; Changey, Sébastien; Basset, Michel

    2015-03-04

    The location of objects is a growing research topic due, for instance, to the expansion of civil drones or intelligent vehicles. This expansion was made possible through the development of microelectromechanical systems (MEMS), inexpensive and miniaturized inertial sensors. In this context, this article describes the development of a new simulator which generates sensor measurements, giving a specific input trajectory. This will allow the comparison of pose estimation algorithms. To develop this simulator, the measurement equations of every type of sensor have to be analytically determined. To achieve this objective, classical kinematic equations are used for the more common sensors, i.e., accelerometers and rate gyroscopes. As nowadays, the MEMS inertial measurement units (IMUs) are generally magnetometer-augmented, an absolute world magnetic model is implemented. After the determination of the perfect measurement (through the error-free sensor models), realistic error models are developed to simulate real IMU behavior. Finally, the developed simulator is subjected to different validation tests.

  1. Construction and Operation of a Differential Hall Element Magnetometer

    NASA Astrophysics Data System (ADS)

    Calkins, Matthew W.; Javernick, Philip D.; Quintero, Pedro A.; Calm, Yitzi M.; Meisel, Mark W.

    2012-02-01

    A Differential Hall Element Magnetometer (DHEM) was constructed to measure the magnetic saturation and coercive fields of small samples consisting of magnetic nanoparticles that may have biomedical applications. The device consists of two matched Hall elements that can be moved through the room temperature bore of a 9 Tesla superconducting magnet. The Hall elements are wired in opposition such that a null response, to within a small offset, is measured in the absence of a sample that may be located on top of one unit. A LabVIEW program controls the current through the Hall elements and measures the net Hall voltage while simultaneously moving the probe through the magnetic field by regulating a linear stepper motor. Ultimately, the system will be tested to obtain a figure of merit using successively smaller samples. Details of the apparatus will be provided along with preliminary data.

  2. Towards a Radiation Hardened Fluxgate Magnetometer for Space Physics Applications

    NASA Astrophysics Data System (ADS)

    Miles, David M.

    Space-based measurements of the Earth's magnetic field are required to understand the plasma processes of the solar-terrestrial connection which energize the Van Allen radiation belts and cause space weather. This thesis describes a fluxgate magnetometer payload developed for the proposed Canadian Space Agencys Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS) mission. The instrument can resolve 8 pT on a 65,000 nT field at 900 samples per second with a magnetic noise of less than 10 pT per square-root Hertz at 1 Hertz. The design can be manufactured from radiation tolerant (100 krad) space grade parts. A novel combination of analog temperature compensation and digital feedback simplifies and miniaturises the instrument while improving the measurement bandwidth and resolution. The prototype instrument was successfully validated at the Natural Resources Canada Geomagnetics Laboratory, and is being considered for future ground, satellite and sounding rocket applications.

  3. Magnetoencephalography using a Multilayer hightc DC SQUID Magnetometer

    NASA Astrophysics Data System (ADS)

    Faley, M. I.; Poppe, U.; Borkowski, R. E. Dunin; Schiek, M.; Boers, F.; Chocholacs, H.; Dammers, J.; Eich, E.; Shah, N. J.; Ermakov, A. B.; Slobodchikov, V. Yu.; Maslennikov, Yu. V.; Koshelets, V. P.

    We describe tests of the use of a multilayer highTc DC SQUID magnetometer for magnetoencephalography (MEG) and compare our measurements with results obtained using a lowTc SQUID sensor. The integration of bias reversal readout electronics for highTc DC SQUID magnetometry into a commercial MEG data acquisition system is demonstrated. Results of measurements performed on a salinefilled head phantom are shown and the detection of an auditory evoked magnetic response of the human cortex elicited by a stimulus is illustrated. Future modifications of highTc DC SQUID sensors for applications in MEG, in order to reach a resolution of 1 fT/√Hz at 77.5 K over a wide frequency band, are outlined.

  4. A three-axis SQUID-based absolute vector magnetometer.

    PubMed

    Schönau, T; Zakosarenko, V; Schmelz, M; Stolz, R; Anders, S; Linzen, S; Meyer, M; Meyer, H-G

    2015-10-01

    We report on the development of a three-axis absolute vector magnetometer suited for mobile operation in the Earth's magnetic field. It is based on low critical temperature dc superconducting quantum interference devices (LTS dc SQUIDs) with sub-micrometer sized cross-type Josephson junctions and exhibits a white noise level of about 10 fT/Hz(1/2). The width of superconducting strip lines is restricted to less than 6 μm in order to avoid flux trapping during cool-down in magnetically unshielded environment. The long-term stability of the flux-to-voltage transfer coefficients of the SQUID electronics is investigated in detail and a method is presented to significantly increase their reproducibility. We further demonstrate the long-term operation of the setup in a magnetic field varying by about 200 μT amplitude without the need for recalibration.

  5. Highly stable atomic vector magnetometer based on free spin precession.

    PubMed

    Afach, S; Ban, G; Bison, G; Bodek, K; Chowdhuri, Z; Grujić, Z D; Hayen, L; Hélaine, V; Kasprzak, M; Kirch, K; Knowles, P; Koch, H-C; Komposch, S; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemière, Y; Mtchedlishvili, A; Naviliat-Cuncic, O; Piegsa, F M; Prashanth, P N; Quéméner, G; Rawlik, M; Ries, D; Roccia, S; Rozpedzik, D; Schmidt-Wellenburg, P; Severjins, N; Weis, A; Wursten, E; Wyszynski, G; Zejma, J; Zsigmond, G

    2015-08-24

    We present a magnetometer based on optically pumped Cs atoms that measures the magnitude and direction of a 1 μT magnetic field. Multiple circularly polarized laser beams were used to probe the free spin precession of the Cs atoms. The design was optimized for long-time stability and achieves a scalar resolution better than 300 fT for integration times ranging from 80 ms to 1000 s. The best scalar resolution of less than 80 fT was reached with integration times of 1.6 to 6 s. We were able to measure the magnetic field direction with a resolution better than 10 μrad for integration times from 10 s up to 2000 s.

  6. Simultaneously improving the sensitivity and absolute accuracy of CPT magnetometer.

    PubMed

    Liang, Shang-Qing; Yang, Guo-Qing; Xu, Yun-Fei; Lin, Qiang; Liu, Zhi-Heng; Chen, Zheng-Xiang

    2014-03-24

    A new method to improve the sensitivity and absolute accuracy simultaneously for coherent population trapping (CPT) magnetometer based on the differential detection method is presented. Two modulated optical beams with orthogonal circular polarizations are applied, in one of which two magnetic resonances are excited simultaneously by modulating a 3.4GHz microwave with Larmor frequency. When a microwave frequency shift is introduced, the difference in the power transmitted through the cell in each beam shows a low noise resonance. The sensitivity of 2pT/Hz @ 10Hz is achieved. Meanwhile, the absolute accuracy of ± 0.5nT within the magnetic field ranging from 20000nT to 100000nT is realized.

  7. A Digital Filter Representation of the ASQ-81 Magnetometer

    DTIC Science & Technology

    1983-09-01

    81 magnetometer filter transfer functions. The input to the fixed high pass filter is called SIG (T), where I is the current data sample. The output...forth, and the symbol * denotes multiplication. For the fixed high pass filter: YO(I)=BFHPO* SIG (I) + BFHPl* SIG (I-1) + BFHP2* SIG (I-2) + AFHP1*YO(I-l...LU z - 0 -0 (4 ’ 0 1 0 LUL * U. . (li) . u ii w 0U c C33 -0 u- V ’ 0 co ij (3 %P 0-4 ( .1 - jue MOOC C (0JU) *d tn0C-QCI,- tn f-i -i."" a1 0 c

  8. Fiber-optic three axis magnetometer prototype development

    NASA Technical Reports Server (NTRS)

    Wang, Thomas D.; Mccomb, David G.; Kingston, Bradley R.; Dube, C. Michael; Poehls, Kenneth A.; Wanser, Keith

    1989-01-01

    The goal of this research program was to develop a high sensitivity, fiber optic, interferometric, three-axis magnetometer for interplanetary spacecraft applications. Dynamics Technology, Inc. (DTI) has successfully integrated a low noise, high bandwidth interferometer with high sensitivity metallic glass transducers. Also, DTI has developed sophisticated signal processing electronics and complete data acquisition, filtering, and display software. The sensor was packaged in a compact, low power and weight unit which facilitates deployment. The magnetic field sensor had subgamma sensitivity and a dynamic range of 10(exp 5) gamma in a 10 Hz bandwidth. Furthermore, the vector instrument exhibited the lowest noise level when only one axis was in operation. A system noise level of 1 gamma rms was observed in a 1 Hz bandwidth. However, with the other two channels operating, the noise level increased by about one order of magnitude. Higher system noise was attributed to cross-channel interference among the dither fields.

  9. Ultrasensitive 3He magnetometer for measurements of high magnetic fields

    NASA Astrophysics Data System (ADS)

    Nikiel, Anna; Blümler, Peter; Heil, Werner; Hehn, Manfred; Karpuk, Sergej; Maul, Andreas; Otten, Ernst; Schreiber, Laura M.; Terekhov, Maxim

    2014-11-01

    We describe a 3He magnetometer capable to measure high magnetic fields ( B> 0.1 T) with a relative accuracy of better than 10-12. Our approach is based on the measurement of the free induction decay of gaseous, nuclear spin polarized 3He following a resonant radio frequency pulse excitation. The measurement sensitivity can be attributed to the long coherent spin precession time T2 ∗ being of order minutes which is achieved for spherical sample cells in the regime of "motional narrowing" where the disturbing influence of field inhomogeneities is strongly suppressed. The 3He gas is spin polarized in situ using a new, non-standard variant of the metastability exchange optical pumping. We show that miniaturization helps to increase T2 ∗ further and that the measurement sensitivity is not significantly affected by temporal field fluctuations of order 10-4.

  10. Magnetometer-Augmented IMU Simulator: In-Depth Elaboration

    PubMed Central

    Brunner, Thomas; Lauffenburger, Jean-Philippe; Changey, Sébastien; Basset, Michel

    2015-01-01

    The location of objects is a growing research topic due, for instance, to the expansion of civil drones or intelligent vehicles. This expansion was made possible through the development of microelectromechanical systems (MEMS), inexpensive and miniaturized inertial sensors. In this context, this article describes the development of a new simulator which generates sensor measurements, giving a specific input trajectory. This will allow the comparison of pose estimation algorithms. To develop this simulator, the measurement equations of every type of sensor have to be analytically determined. To achieve this objective, classical kinematic equations are used for the more common sensors, i.e., accelerometers and rate gyroscopes. As nowadays, the MEMS inertial measurement units (IMUs) are generally magnetometer-augmented, an absolute world magnetic model is implemented. After the determination of the perfect measurement (through the error-free sensor models), realistic error models are developed to simulate real IMU behavior. Finally, the developed simulator is subjected to different validation tests. PMID:25746095

  11. A three-axis SQUID-based absolute vector magnetometer

    SciTech Connect

    Schönau, T.; Schmelz, M.; Stolz, R.; Anders, S.; Linzen, S.; Meyer, H.-G.; Zakosarenko, V.; Meyer, M.

    2015-10-15

    We report on the development of a three-axis absolute vector magnetometer suited for mobile operation in the Earth’s magnetic field. It is based on low critical temperature dc superconducting quantum interference devices (LTS dc SQUIDs) with sub-micrometer sized cross-type Josephson junctions and exhibits a white noise level of about 10 fT/Hz{sup 1/2}. The width of superconducting strip lines is restricted to less than 6 μm in order to avoid flux trapping during cool-down in magnetically unshielded environment. The long-term stability of the flux-to-voltage transfer coefficients of the SQUID electronics is investigated in detail and a method is presented to significantly increase their reproducibility. We further demonstrate the long-term operation of the setup in a magnetic field varying by about 200 μT amplitude without the need for recalibration.

  12. Magsat vector magnetometer calibration using Magsat geomagnetic field measurements

    NASA Technical Reports Server (NTRS)

    Lancaster, E. R.; Jennings, T.; Morrissey, M.; Langel, R. A.

    1980-01-01

    From the time of its launch on Oct. 30, 1979 into a nearly polar, Sun synchronous orbit, until it reentered the Earth's atmosphere on June 11, 1980, Magsat measured and transmitted more than three complete sets of global magnetic field data. The data obtained from the mission will be used primarily to compute a currently accurate model of the Earth's main magnetic field, to update and refine world and regional magnetic charts, and to develop a global scalar and vector crustal magnetic anomaly map. The in-flight calibration procecure used for 39 vector magnetometer system parameters is described as well as results obtained from some data sets and the numerical studies designed to evaluate the results.

  13. The Search-coil Magnetometer for the THOR mission

    NASA Astrophysics Data System (ADS)

    Sahraoui, Fouad; Pinçon, Jean-louis; Jannet, Guillaume; Mansour, Malik; Henri, Pierre; Chalumeau, Gilles; Hachemi, Tedjani; Jeandet, Alexis; Briand, Nicolas; Le Contel, Olivier; Rezeau, Laurence

    2016-04-01

    Turbulence Heating ObserveR (THOR) is the first mission ever flown in space fully dedicated to plasma turbulence. The search-coil magnetometer (SCM) of THOR is a triaxial dual-band antenna dedicated to measuring the magnetic field fluctuations in the frequency range [1Hz,4kHz] and [1,200]kHz. THOR/SCM has a long heritage from earlier space missions such as Cluster, Themis, MMS, BepiColombo, Taranis, Solar orbiter and Solar Probe. In comparison to those missions, the SCM of THOR has a higher sensitivity level, which makes it capable of measuring very low amplitude magnetic fluctuations, in particular in the solar wind. Those measurements are crucial to address the problem of turbulence and energy dissipation at electron scales, a central goal of the THOR mission.

  14. A Tow-Level Progressive Damage for Simulating Carbon-Fiber Textile Composites: Interim Report

    SciTech Connect

    Zywicz, E.

    2000-07-01

    A numerical approach to model the elasto-plastic and tensile damage response of tri-axially braided carbon-fiber polymeric-matrix composites is developed. It is micromechanically based and consists of a simplified unit cell geometry, a plane-stress tow-level constitutive relationship, a one-dimensional undulation constitutive law, and a non-traditional shell element integration rule. The braided composite lamina is idealized as periodic in the plane, and a simplified three-layer representative volume (RV) is assembled from axial and braider tows and pure resin regions. The constituents in each layer are homogenized with an iso-strain assumption in the fiber-direction and an iso-stress condition in the other directions. In the upper and lower layers, the fiber-direction strain is additively decomposed into an undulation and a tow portion. A finite-deformation tow model predicts the plane-stress tow response and is coupled to the undulation constitutive relationship. The overall braid model is implemented in DYNA3D and works with traditional shell elements. The finite-deformation tow constitutive relationship is derived from the fiber elasticity and the isotropic elasto-plastic power-law hardening matrix response using a thermodynamic framework and simple homogenization assumptions. The model replicates tensile damage evolution, in a smeared sense, parallel and perpendicular to the fiber axis and is regularized to yield mesh independent results. The tow-level model demonstrates reasonable agreement, prior to damage, with detailed three-dimensional FE (finite element) elasto-plastic simulations of aligned, periodically arranged, uni-directional composites. The 3-layer braid model response is compared with predictions obtained from detailed micromechanical simulations of the braid's unit cell in uni-axial extension, shear, and flexure for three braid angles. The elastic properties show good agreement as does the non-linear response for loadings dominated by the axial

  15. A Model for Tow Impregnation and Consolidation for Partially Impregnated Thermoset Prepregs

    SciTech Connect

    John J. Gangloff Jr; Shatil Sinha; Suresh G. Advani

    2011-05-23

    The formation and transport of voids in composite materials remains a key research area in composite manufacturing science. Knowledge of how voids, resin, and fiber reinforcement propagate throughout a composite material continuum from green state to cured state during an automated tape layup process is key to minimizing defects induced by void-initiated stress concentrations under applied loads for a wide variety of composite applications. This paper focuses on modeling resin flow in a deforming fiber tow during an automated process of partially impregnated thermoset prepreg composite material tapes. In this work, a tow unit cell based model has been presented that determines the consolidation and impregnation of a thermoset prepreg tape under an input pressure profile. A parametric study has been performed to characterize the behavior of varying tow speed and compaction forces on the degree of consolidation. Results indicate that increased tow consolidation is achieved with slower tow speeds and higher compaction forces although the relationship is not linear. The overall modeling of this project is motivated to address optimization of the 'green state' composite properties and processing parameters to reduce or eliminate 'cured state' defects, such as porosity and de-lamination. This work is partially funded by the Department of Energy under Award number DE-EE0001367.

  16. A continuously towed vertical bipole source for marine magnetometric resistivity surveying

    NASA Astrophysics Data System (ADS)

    Seama, Nobukazu; Tada, Noriko; Goto, Tada-nori; Shimoizumi, Masashi

    2013-08-01

    We propose to use an approximately vertical bipole electric current towed by a ship as a source for a Magnetometric Resistivity (MMR) method. This proposal requires the precise positioning of the bottom electrode for the bipole source, and our newly developed MMR system achieved this. We conducted an MMR experiment in the central Mariana Trough, and we obtained data using two different methods along a survey line: one method towed a bipole source transmitting continuously along the survey line, and the other used a conventional vertical bipole source transmitting at several stationary transmission stations along the survey line. We found that the towed bipole source tilted from the vertical by an angle of 8 degrees at the maximum during the MMR experiment. We compared the results from the two methods to evaluate the towed bipole source method. Our results indicate that the tilted bipole source approximates well with the vertical bipole source at the mid-point between the surface and the bottom electrodes. Since the towed bipole source method requires much less survey time and the results show a higher spatial resolution, it is a powerful tool for MMR experiments to image a shallow oceanic crustal resistivity structure efficiently.

  17. Anisotropic 3D inversion of towed streamer EM data from the Troll West oil province (Invited)

    NASA Astrophysics Data System (ADS)

    Mattsson, J.; Midgley, J.; Zhdanov, M. S.; ENDO, M.

    2013-12-01

    Obviating the need for ocean bottom receivers, the towed streamer EM system enables CSEM data to be acquired simultaneously with seismic over very large areas in frontier and mature basins for higher production rates and more cost effective than conventional marine CSEM. The towed streamer EM data are currently processed and delivered as a spectrum of frequency-domain responses. We apply a 3D anisotropic inversion methodology for towed streamer EM data that includes a moving sensitivity domain. Our implementation is based on the 3D contraction integral equation method for computing the EM responses and Fréchet derivatives, and uses the re-weighted regularized conjugate gradient method for minimizing the objective functional with focusing regularization. We present an actual case study for the 3D anisotropic inversion of towed streamer EM data from the Troll West oil province in the North Sea, and demonstrate our ability to image the Troll West Oil and Gas Provinces. We conclude that 3D anisotropic inversion of the data from the current generation of towed streamer EM system can adequately recover both the vertical and horizontal resistivities in anisotropic hydrocarbon-bearing formations.

  18. Full Scale Tunnel (FST) and Seaplane Tow Channel

    NASA Technical Reports Server (NTRS)

    1930-01-01

    Aerial and ground views of the overall construction of Full-Scale Tunnel (FST) and the Seaplane Tow Channel. In November 1929, Smith DeFrance submitted his recommendations for the general design of the Full Scale Wind Tunnel. The last on his list concerned the division of labor required to build this unusual facility. He believed the job had five parts and described them as follows: 'It is proposed that invitations be sent out for bids on five groups of items. The first would be for one contract on the complete structure; second the same as first, including the erection of the cones but not the fabrication, since this would be more of a shipyard job; third would cover structural steel, cover, sash and doors, but not cones or foundation; fourth, foundations; an fifth, fabrication of cones.' DeFrance's memorandum prompted the NACA to solicit estimates from a large number of companies. Preliminary designs and estimates were prepared and submitted to the Bureau of the Budget and Congress appropriated funds on February 20, 1929. The main construction contract with the J.A. Jones Company of Charlotte, North Carolina was signed one year later on February 12, 1930. It was a peculiar structure as the building's steel framework is visible on the outside of the building. DeFrance described this in NACA TR No. 459: 'The entire equipment is housed in a structure, the outside walls of which serve as the outer walls of the return passages. The over-all length of the tunnel is 434 feet 6 inches, the width 222 feet, and the maximum height 97 feet. The framework is of structural steel....' (pp. 292-293). Ground shots of work in progress, aerials of east area.

  19. Full Scale Wind Tunnel and Seaplane Tow Channel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Construction progress, studding in Tow Channel office area, Full Scale motor fairing in west exit cone, motor fairing in east exit cone. Propeller and motor fairing for west exit cone. Smith DeFrance described the propellers and motors in NACA TR No. 459. ' The propellers are located side by side and 48 feet aft of the throat of the exit-cone bell. The propellers are 35 feet 5 inches in diameter and each consists of four cast aluminum alloy blades screwed into a cast steel hub.' 'The most commonly used power plant for operating a wind tunnel is a direct-current motor and motor-generator set with Ward Leonard control system. For the full-scale wind tunnel it was found that alternating current slip-ring induction motors, together with satisfactory control equipment, could be purchased for approximately 30 percent less than the direct-current equipment. Two 4,000-horsepower slip-ring induction motors with 24 steps of speed between 75 and 300 r.p.m. were therefore installed. In order to obtain the range of speed one pole change was provided and the other variations are obtained by the introduction of resistance in the rotor circuit. This control permits a variation in air speed from 25 to 118 miles per hour. The two motors are connected through an automatic switchboard to one drum-type controller located in the test chamber. All the control equipment is interlocked and connected through time-limit relays, so that regardless of how fast the controller handle is moved the motors will increase in speed at regular intervals.' (p. 294-295)

  20. Monitoring tidal currents with a towed ADCP system

    NASA Astrophysics Data System (ADS)

    Sentchev, Alexei; Yaremchuk, Max

    2016-01-01

    The tidal circulation in the semi-enclosed Boulogne harbour (eastern English Channel) is measured during the various stages of the tidal cycle with a low-cost towed Acoustic Doppler Current Profiler (ADCP) system for the first time. The system is equipped with an interpolation algorithm which allows reconstructing space-time evolution of the velocity field for surveys whose duration is comparable or larger than the typical time of tidal variation (1-2 h). The method employs space-time velocity covariances derived from a numerical simulation of the surveyed area by a high-resolution relocatable model "Model for Applications on Regional Scale" (MARS). The covariances are utilized by the optimal interpolation algorithm to obtain the most likely evolution of the velocity field under the constraints provided by the ADCP observations and their error statistics. Technically, the MARS model run provides the first guess (background) evolution of the velocity field in the surveyed area which is then corrected by the data in a statistically consistent manner as it explicitly takes into the account both observational and modeling errors. The quality of the velocity reconstruction was validated against independent bottom-mounted ADCP data, the background model evolution, and against the results of spatial interpolation by Kriging technique. All tests demonstrated significant (30 to 60 %) reduction of the model-data misfit for the velocity field obtained as a result of space-time optimal interpolation. Although the method was applied to recover surface circulation, it can be extended for assessment of the full 4D tidal flow dynamics using the data recorded throughout the entire water column.

  1. An experimental investigation of the improvement in the reception of TM (Transverse Magnetic)-polarized LF (Low-Frequency) waves with a two-element spaced array

    NASA Astrophysics Data System (ADS)

    Tingley, F. M.; Kahler, R. C.

    1984-05-01

    For this study, a 2-element spaced array antenna system was developed and tested. This array consisted of two well-spaced vertical loops combined with a microwave link. The array was tested to show improvements in signal-to-noise ratio over omnidirectional antennas, using received transmissions from an aircraft towing a long wire antenna. Gains in signal-to-noise ratio of up to 12.8 dB were demonstrated.

  2. A Comparison of Some Signal-Processing Algorithms to Suppress Tow-Vessel Noise in a Towed Array, with Results from a Shallow-Water Trial

    DTIC Science & Technology

    1982-10-01

    2), 1,NH) PR(NHE,2)=QS»100. PR(NHE, 1)=P0W C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C PRELIMINARY SPLIT BEAM PROCESSING C NN(1...0482 0483 0484 C 819 FORMAKX, 13, 2F8. 1,2X,20F4. 3, 2X, 16) - C ccccccccccccccccccccccccccccccccccccccccccccc c C CONTINUE SPLIT BEAM PROCESSING c

  3. Effects of magnetometer calibration and maneuvers on accuracies of magnetometer-only attitude-and-rate determination

    NASA Technical Reports Server (NTRS)

    Challa, M.; Natanson, G.

    1998-01-01

    Two different algorithms - a deterministic magnetic-field-only algorithm and a Kalman filter for gyroless spacecraft - are used to estimate the attitude and rates of the Rossi X-Ray Timing Explorer (RXTE) using only measurements from a three-axis magnetometer. The performance of these algorithms is examined using in-flight data from various scenarios. In particular, significant enhancements in accuracies are observed when' the telemetered magnetometer data are accurately calibrated using a recently developed calibration algorithm. Interesting features observed in these studies of the inertial-pointing RXTE include a remarkable sensitivity of the filter to the numerical values of the noise parameters and relatively long convergence time spans. By analogy, the accuracy of the deterministic scheme is noticeably lower as a result of reduced rates of change of the body-fixed geomagnetic field. Preliminary results show the filter-per-axis attitude accuracies ranging between 0.1 and 0.5 deg and rate accuracies between 0.001 deg/sec and 0.005 deg./sec, whereas the deterministic method needs a more sophisticated techniques for smoothing time derivatives of the measured geomagnetic field to clearly distinguish both attitude and rate solutions from the numerical noise. Also included is a new theoretical development in the deterministic algorithm: the transformation of a transcendental equation in the original theory into an 8th-order polynomial equation. It is shown that this 8th-order polynomial reduces to quadratic equations in the two limiting cases-infinitely high wheel momentum, and constant rates-discussed in previous publications.

  4. Measuring MEG closer to the brain: Performance of on-scalp sensor arrays.

    PubMed

    Iivanainen, Joonas; Stenroos, Matti; Parkkonen, Lauri

    2017-02-15

    Optically-pumped magnetometers (OPMs) have recently reached sensitivity levels required for magnetoencephalography (MEG). OPMs do not need cryogenics and can thus be placed within millimetres from the scalp into an array that adapts to the individual head size and shape, thereby reducing the distance from cortical sources to the sensors. Here, we quantified the improvement in recording MEG with hypothetical on-scalp OPM arrays compared to a 306-channel state-of-the-art SQUID array (102 magnetometers and 204 planar gradiometers). We simulated OPM arrays that measured either normal (nOPM; 102 sensors), tangential (tOPM; 204 sensors), or all components (aOPM; 306 sensors) of the magnetic field. We built forward models based on magnetic resonance images of 10 adult heads; we employed a three-compartment boundary element model and distributed current dipoles evenly across the cortical mantle. Compared to the SQUID magnetometers, nOPM and tOPM yielded 7.5 and 5.3 times higher signal power, while the correlations between the field patterns of source dipoles were reduced by factors of 2.8 and 3.6, respectively. Values of the field-pattern correlations were similar across nOPM, tOPM and SQUID gradiometers. Volume currents reduced the signals of primary currents on average by 10%, 72% and 15% in nOPM, tOPM and SQUID magnetometers, respectively. The information capacities of the OPM arrays were clearly higher than that of the SQUID array. The dipole-localization accuracies of the arrays were similar while the minimum-norm-based point-spread functions were on average 2.4 and 2.5 times more spread for the SQUID array compared to nOPM and tOPM arrays, respectively.

  5. Optimization of the first order gradiometer for small sample magnetization measurements using pulse integrating magnetometer

    SciTech Connect

    Trojanowski, S.; Ciszek, M.

    2009-10-15

    In the paper we present an analytical calculation method for determination of the sensitivity of a pulse field magnetometer working with a first order gradiometer. Our considerations here are especially focused on a case of magnetic moment measurements of very small samples. Derived in the work analytical equations allow for a quick estimation of the magnetometer's sensitivity and give also the way to its calibration using the sample simulation coil method. On the base of the given in the paper calculations we designed and constructed a simple homemade magnetometer and performed its sensitivity calibration.

  6. Optimization of the first order gradiometer for small sample magnetization measurements using pulse integrating magnetometer.

    PubMed

    Trojanowski, S; Ciszek, M

    2009-10-01

    In the paper we present an analytical calculation method for determination of the sensitivity of a pulse field magnetometer working with a first order gradiometer. Our considerations here are especially focused on a case of magnetic moment measurements of very small samples. Derived in the work analytical equations allow for a quick estimation of the magnetometer's sensitivity and give also the way to its calibration using the sample simulation coil method. On the base of the given in the paper calculations we designed and constructed a simple homemade magnetometer and performed its sensitivity calibration.

  7. Effects of resisted sled towing on sprint kinematics in field-sport athletes.

    PubMed

    Lockie, Robert G; Murphy, Aron J; Spinks, Christopher D

    2003-11-01

    Weighted sled towing is a common resisted sprint training technique even though relatively little is known about the effects that such practice has on sprint kinematics. The purpose of this study was to explore the effects of sled towing on acceleration sprint kinematics in field-sport athletes. Twenty men completed a series of sprints without resistance and with loads equating to 12.6 and 32.2% of body mass. Stride length was significantly reduced by approximately 10 and approximately 24% for each load, respectively. Stride frequency also decreased, but not to the extent of stride length. In addition, sled towing increased ground contact time, trunk lean, and hip flexion. Upper-body results showed an increase in shoulder range of motion with added resistance. The heavier load generally resulted in a greater disruption to normal acceleration kinematics compared with the lighter load. The lighter load is likely best for use in a training program.

  8. Determining the optimal load for resisted sprint training with sled towing.

    PubMed

    Alcaraz, Pedro E; Palao, José Manuel; Elvira, José L L

    2009-03-01

    An excessive load in resisted sprint training can produce changes in running patterns. Therefore, load control is essential to ensure the specificity of these training methods. The most common way to control it is through the percentage of velocity lost in relation to maximum velocity. The present paper describes a study that aimed to establish the load for sprint training with sled towing. The study developed a regression equation for calculating the load in the maximum velocity phase. The calculation was done with 26 athletes from the Spanish and French national levels on a synthetic track surface and with spikes. The regression equation obtained was % body mass = (-0.8674 x % velocity) + 87.99. The equation, although specific for type of surface used and sled towing characteristics, is useful in establishing the optimal load for acceleration and maximum velocity training with sled towing.

  9. Micro-shimmy of towed structures in experimentally uncharted unstable parameter domain

    NASA Astrophysics Data System (ADS)

    Takács, Dénes; Stépán, Gábor

    2012-11-01

    In this paper, the lateral instability of towed structures (trailers, caravans and articulated buses) is investigated with special attention to the small amplitude lateral vibration that leads to a higher energy consumption in certain parameter domains. A low degree-of-freedom mechanical model of a shimmying towed tyre is used that describes the dynamics of the tyre-ground contact patch by the time delayed differential equation. Stability charts are calculated and the theoretically predicted linear unstable islands of small amplitude shimmy motions are validated by laboratory experiments. A tyre is towed by a relatively long caster, and its temperature and the input current of the conveyor belt are measured in order to show the increased value of the rolling resistance.

  10. Kokkos Array

    SciTech Connect

    Edwards Daniel Sunderland, Harold Carter

    2012-09-12

    The Kokkos Array library implements shared-memory array data structures and parallel task dispatch interfaces for data-parallel computational kernels that are performance-portable to multicore-CPU and manycore-accelerator (e.g., GPGPU) devices.

  11. 49 CFR 214.525 - Towing with on-track roadway maintenance machines or hi-rail vehicles.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... or hi-rail vehicles. 214.525 Section 214.525 Transportation Other Regulations Relating to... SAFETY On-Track Roadway Maintenance Machines and Hi-Rail Vehicles § 214.525 Towing with on-track roadway maintenance machines or hi-rail vehicles. (a) When used to tow pushcars or other maintenance-of-way...

  12. 46 CFR 130.250 - Mooring and towing equipment for OSVs of less than 100 gross tons.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mooring and towing equipment for OSVs of less than 100 gross tons. 130.250 Section 130.250 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... Systems § 130.250 Mooring and towing equipment for OSVs of less than 100 gross tons. Each OSV of less...

  13. 46 CFR 27.301 - What are the requirements for fire pumps, fire mains, and fire hoses on towing vessels?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false What are the requirements for fire pumps, fire mains... the requirements for fire pumps, fire mains, and fire hoses on towing vessels? By April 29, 2005, you must provide for your towing vessel either a self-priming, power-driven, fixed fire-pump, a fire...

  14. Nanocylinder arrays

    DOEpatents

    Tuominen, Mark; Schotter, Joerg; Thurn-Albrecht, Thomas; Russell, Thomas P.

    2007-03-13

    Pathways to rapid and reliable fabrication of nanocylinder arrays are provided. Simple methods are described for the production of well-ordered arrays of nanopores, nanowires, and other materials. This is accomplished by orienting copolymer films and removing a component from the film to produce nanopores, that in turn, can be filled with materials to produce the arrays. The resulting arrays can be used to produce nanoscale media, devices, and systems.

  15. Nanocylinder arrays

    DOEpatents

    Tuominen, Mark; Schotter, Joerg; Thurn-Albrecht, Thomas; Russell, Thomas P.

    2009-08-11

    Pathways to rapid and reliable fabrication of nanocylinder arrays are provided. Simple methods are described for the production of well-ordered arrays of nanopores, nanowires, and other materials. This is accomplished by orienting copolymer films and removing a component from the film to produce nanopores, that in turn, can be filled with materials to produce the arrays. The resulting arrays can be used to produce nanoscale media, devices, and systems.

  16. Comparison of Curvilinear Stiffeners and Tow Steered Composites for Aeroelastic Tailoring of Transports

    NASA Technical Reports Server (NTRS)

    Stanford, Bret K.; Jutte, Christine V.

    2016-01-01

    A series of aeroelastic optimization problems are solved on a high aspect ratio wingbox of the Common Research Model, in an effort to minimize structural mass under coupled stress, buckling, and flutter constraints. Two technologies are of particular interest: tow steered composite laminate skins and curvilinear stiffeners. Both methods are found to afford feasible reductions in mass over their non-curvilinear structural counterparts, through both distinct and shared mechanisms for passively controlling aeroelastic performance. Some degree of diminishing returns are seen when curvilinear stiffeners and curvilinear fiber tow paths are used simultaneously.

  17. A numerical study for design of depth, pitch and roll control system of a towed vehicle

    SciTech Connect

    Koterayama, W.; Yamaguchi, S.; Nakamura, M.; Moriyama, A.; Akamatsu, T.

    1994-12-31

    A towed vehicle system, FLYING FISH, is under development for use in making chemical and physical measurements which enable the authors to obtain spacially continuous and real time data in an ocean mixed layer. The heave, pitch and roll of FLYING FISH are controlled by a main wing and horizontal tail wings which permit its stable attitudes and assure accurate measurements. The numerical simulation of motions was carried out to design the optimal control system of this towed vehicle system and the results gave the data for the design of the mechanical parts of the control system.

  18. Monitoring of the mass density profile along the 0° geomagnetic longitude during magnetic storms with the use of ground magnetometers.

    NASA Astrophysics Data System (ADS)

    Romanova, N.; Stepanova, M. V.; Kozyreva, O. V.; Pilipenko, V.; Zesta, E.

    2015-12-01

    Ground magnetometers offer a very cheap and robust means of globally monitoring the magnetospheric mass density, by determining the ULF field line resonant frequency. ULF waves are almost always present in near-Earth environment and are generated by the solar wind interaction with the terrestrial magnetosphere. These waves from the magnetopause propagate through the magnetosphere. When they encounter a field line that resonates at the same frequency, coupling to the Alfven field line oscillations occurs and the resonance can be detected on the ground at that particular latitude. There are different methods for determining resonant frequencies from ground ULF waves. the density profiles along the 0° geomagnetic longitude were obtained using both the gradient and the amplitude-phase methods for the analysis of the magnetic field data from the magnetometer arrays: SAMBA (South American Meridional B-field Array), MAGDAS and American Antarctic bases (Palmer, WAIS-D). We compared the density profiles during quiet magnetic conditions and during strong magnetic storms (recovery phase). It is shown that in the recovery phase of strong magnetic storms (Dst <-150 nT) profile of the equatorial mass density varies greatly in comparison with the density distribution in quiet days.

  19. Eclipse project QF-106 and C-141A climbs out under tow on first tethered flight December 20, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    TOW LAUNCH DEMONSTRATION - The Kelly Space & Technology (KST)/USAF/NASA Eclipse project's modified QF-106 climbs out under tow by a USAF C-141A on the project's first tethered flight on December 20, 1997. The successful 18-minute-long flight reached an altitude of 10,000 feet. NASA's Dryden Flight Research Center, Edwards, California, hosted the project, providing engineering and facility support as well as the project pilot. In 1997 and 1998, the Dryden Flight Research Center at Edwards, California, supported and hosted a Kelly Space & Technology, Inc. project called Eclipse, which sought to demonstrate the feasibility of a reusable tow-launch vehicle concept. The project goal was to successfully tow, inflight, a modified QF-106 delta-wing aircraft with an Air Force C-141A transport aircraft. This would demonstrate the possibility of towing and launching an actual launch vehicle from behind a tow plane. Dryden was the responsible test organization and had flight safety responsibility for the Eclipse project. Dryden provided engineering, instrumentation, simulation, modification, maintenance, range support, and research pilots for the test program. The Air Force Flight Test Center (AFFTC), Edwards, California, supplied the C-141A transport aircraft and crew and configured the aircraft as needed for the tests. The AFFTC also provided the concept and detail design and analysis as well as hardware for the tow system and QF-106 modifications. Dryden performed the modifications to convert the QF-106 drone into the piloted EXD-01 (Eclipse eXperimental Demonstrator-01) experimental aircraft. Kelly Space & Technology hoped to use the results gleaned from the tow test in developing a series of low-cost, reusable launch vehicles. These tests demonstrated the validity of towing a delta-wing aircraft having high wing loading, validated the tow simulation model, and demonstrated various operational procedures, such as ground processing of in-flight maneuvers and emergency abort

  20. Solid-State Multimission Magnetometer (SSM(3)): Application to Groundwater Exploration on Mars

    NASA Technical Reports Server (NTRS)

    Grimm, Robert E.

    2002-01-01

    This report describes work to develop solid-state magnetometers using magnetoresistive thin films, low-frequency electric-field measurements, and methods for electromagnetic detection of water and ice in the subsurface of Mars.

  1. Effect of coupling line design on the performance of direct coupled high-Tc SQUID magnetometers

    NASA Astrophysics Data System (ADS)

    Kim, In Seon; Yu, Kwon Kyu; Park, Yong Ki

    2004-03-01

    YBCO dc SQUID magnetometers based on bicrystal Josephson junctions on 10 mm × 10 mm STO substrates have been fabricated. We have designed 16-parallel-loop pickup coil SQUID magnetometers with 50 μ m line width for use under a magnetically disturbed environment. The magnetometers exhibit stable flux locked loop operation under magnetically very noisy laboratory environment. We modified the coupling scheme between pickup coil and SQUID washer to replace the conventional narrow and long interconnection lines to reduce the residual inductance of the coupling lines. With the coupling line modification the effective area increased more than 12%. Finally, we could obtain optimized direct coupled YBCO SQUID magnetometer design having field sensitivity B_Φ of 4.5 nT/Φ 0 and magnetic field noise BN of 30 fT/Hz^1/2 measured at 100 Hz.

  2. Ultra-sensitive high-density Rb-87 radio-frequency magnetometer

    SciTech Connect

    Savukov, I.; Boshier, M. G.; Karaulanov, T.

    2014-01-13

    Radio-frequency (RF) atomic magnetometers (AMs) can be used in many applications, such as magnetic resonance imaging and nuclear quadrupole resonance. High-density AMs provide both superior sensitivity and large bandwidth. Previously, high-density potassium AMs were demonstrated, but these magnetometers have various disadvantages, such as high-temperature of operation and bulky design. We demonstrate a rubidium-87 RF AM with 5 fT/Hz{sup 1/2} sensitivity (3 fT Hz{sup 1/2} probe noise), which is comparable to that of the best potassium magnetometers. Our magnetometer also features a simple fiber-optic design, providing maximum flexibility for magnetic-field measurements.

  3. A rubidium Mx-magnetometer for measurements on solid state spins

    NASA Astrophysics Data System (ADS)

    Arnold, Daniel; Siegel, Steven; Grisanti, Emily; Wrachtrup, Jörg; Gerhardt, Ilja

    2017-02-01

    The detection of environmental magnetic fields is well established by optically pumped atomic magnetometers. Another focus of magnetometry can be the research on magnetic or spin-active solid-state samples. Here we introduce a simple and compact design of a rubidium-based Mx magnetometer, which allows for hosting solid-state samples. The optical, mechanical, and electrical design is reported, as well as simple measurements which introduce the ground-state spin-relaxation time, the signal-to-noise ratio of a measurement, and subsequently the overall sensitivity of the magnetometer. The magnetometer is optimized for the most sensitive operation with respect to laser power and magnetic field excitation at the Larmor frequency.

  4. A rubidium Mx-magnetometer for measurements on solid state spins.

    PubMed

    Arnold, Daniel; Siegel, Steven; Grisanti, Emily; Wrachtrup, Jörg; Gerhardt, Ilja

    2017-02-01

    The detection of environmental magnetic fields is well established by optically pumped atomic magnetometers. Another focus of magnetometry can be the research on magnetic or spin-active solid-state samples. Here we introduce a simple and compact design of a rubidium-based Mx magnetometer, which allows for hosting solid-state samples. The optical, mechanical, and electrical design is reported, as well as simple measurements which introduce the ground-state spin-relaxation time, the signal-to-noise ratio of a measurement, and subsequently the overall sensitivity of the magnetometer. The magnetometer is optimized for the most sensitive operation with respect to laser power and magnetic field excitation at the Larmor frequency.

  5. Novel handheld magnetometer probe based on magnetic tunnelling junction sensors for intraoperative sentinel lymph node identification.

    PubMed

    Cousins, A; Balalis, G L; Thompson, S K; Forero Morales, D; Mohtar, A; Wedding, A B; Thierry, B

    2015-06-03

    Using magnetic tunnelling junction sensors, a novel magnetometer probe for the identification of the sentinel lymph node using magnetic tracers was developed. Probe performance was characterised in vitro and validated in a preclinical swine model. Compared to conventional gamma probes, the magnetometer probe showed excellent spatial resolution of 4.0 mm, and the potential to detect as few as 5 μg of magnetic tracer. Due to the high sensitivity of the magnetometer, all first-tier nodes were identified in the preclinical experiments, and there were no instances of false positive or false negative detection. Furthermore, these preliminary data encourage the application of the magnetometer probe for use in more complex lymphatic environments, such as in gastrointestinal cancers, where the sentinel node is often in close proximity to other non-sentinel nodes, and high spatial resolution detection is required.

  6. Design and analysis of control system for VCSEL of atomic interference magnetometer

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-nan; Sun, Xiao-jie; Kou, Jun; Yang, Feng; Li, Jie; Ren, Zhang; Wei, Zong-kang

    2016-11-01

    Magnetic field detection is an important means of deep space environment exploration. Benefit from simple structure and low power consumption, atomic interference magnetometer become one of the most potential detector payloads. Vertical Cavity Surface Emitting Laser (VCSEL) is usually used as a light source in atomic interference magnetometer and its frequency stability directly affects the stability and sensitivity of magnetometer. In this paper, closed-loop control strategy of VCSEL was designed and analysis, the controller parameters were selected and the feedback error algorithm was optimized as well. According to the results of experiments that were performed on the hardware-in-the-loop simulation platform, the designed closed-loop control system is reasonable and it is able to effectively improve the laser frequency stability during the actual work of the magnetometer.

  7. Novel Handheld Magnetometer Probe Based on Magnetic Tunnelling Junction Sensors for Intraoperative Sentinel Lymph Node Identification

    PubMed Central

    Cousins, A.; Balalis, G. L.; Thompson, S. K.; Forero Morales, D.; Mohtar, A.; Wedding, A. B.; Thierry, B.

    2015-01-01

    Using magnetic tunnelling junction sensors, a novel magnetometer probe for the identification of the sentinel lymph node using magnetic tracers was developed. Probe performance was characterised in vitro and validated in a preclinical swine model. Compared to conventional gamma probes, the magnetometer probe showed excellent spatial resolution of 4.0 mm, and the potential to detect as few as 5 μg of magnetic tracer. Due to the high sensitivity of the magnetometer, all first-tier nodes were identified in the preclinical experiments, and there were no instances of false positive or false negative detection. Furthermore, these preliminary data encourage the application of the magnetometer probe for use in more complex lymphatic environments, such as in gastrointestinal cancers, where the sentinel node is often in close proximity to other non-sentinel nodes, and high spatial resolution detection is required. PMID:26038833

  8. Improving Sensitivity and Bandwidth of an Atomic Magnetometer using Quantum Non-Demolition Measurement

    NASA Astrophysics Data System (ADS)

    Shah, Vishal; Vasilakis, Georgios; Romalis, Michael

    2009-05-01

    The fundamental sensitivity of an atomic magnetometer is limited by spin projection noise. In the case of uniform spin relaxation, it is well understood that it is not possible to improve the sensitivity using spin squeezing induced by quantum non-demolition (QND) measurement for measurement time scales longer than spin relaxation time [1, 2]. It is however possible to increase the bandwidth of the magnetometer using QND measurement. Here we experimentally demonstrate, in excellent agreement with the theory, an improvement in the bandwidth of our scalar alkali vapor atomic magnetometer using continuous QND measurement. We also investigate the possibility of improving sensitivity of our magnetometer in the special case in which the spin relaxation is time dependent. The case of time dependent spin relaxation naturally arises in high polarization regime in an alkali-alkali spin-exchange relaxation dominated atomic sample. [1] S. F. Huelga, Phys. Rev. Lett. 79, 3865 -- 3868, 1997. [2] M. Auzinsh, Phys. Rev. Lett. 93, 173002, 2004.

  9. GSFC magnetic field experiment Explorer 43. [describing magnetometer, data processor, and telemetry

    NASA Technical Reports Server (NTRS)

    Seek, J. B.; Scheifele, J. L.; Ness, N. F.

    1974-01-01

    The magnetic field experiment flown on Explorer 43 is described. The detecting instrument is a triaxial fluxgate magnetometer which is mounted on a boom with a flipping mechanism for reorienting the sensor in flight. An on-board data processor takes successive magnetometer samples and transmits differences to the telemetry system. By examining these differences in conjunction with an untruncated sample transmitted periodically, the original data may be uniquely reconstructed on the ground.

  10. Lunar core detection using data from a single orbiting magnetometer - A feasibility study

    NASA Astrophysics Data System (ADS)

    Hood, L. L.; Hartdegen, K.

    1997-03-01

    An investigation is conducted of the detectability of a lunar core in the presence of a realistic magnetic field and plasma disturbances in the geomagnetic tail, at distances comparable to the lunar orbit radius of 60 Earth radii. The magnetometer and plasma data employed are from ISEE-3, for the period from October 1982 to April 1983. A single orbiting magnetometer is projected to render the core detectable if it is larger than 400 km in radius.

  11. Magnetic induction tomography using an all-optical ⁸⁷Rb atomic magnetometer.

    PubMed

    Wickenbrock, Arne; Jurgilas, Sarunas; Dow, Albert; Marmugi, Luca; Renzoni, Ferruccio

    2014-11-15

    We demonstrate magnetic induction tomography (MIT) with an all-optical atomic magnetometer. Our instrument creates a conductivity map of conductive objects. Both the shape and size of the imaged samples compare very well with the actual shape and size. Given the potential of all-optical atomic magnetometers for miniaturization and extreme sensitivity, the proof-of-principle presented in this Letter opens up promising avenues in the development of instrumentation for MIT.

  12. Estimation of Depth, Orientation, Length and Diameter of Long, Horizontal Ferrous Rods Using a Fluxgate Magnetometer

    DTIC Science & Technology

    1993-04-01

    applications where a horizontal ferrous rod, rope, pipe or cable lies underneath a smooth planar surface at a constant depth. In such cases one often...Brown sensor as the preferred magnetometer and by constructing preliminary magnetometer sensors and circuits. Richard Pinnell , formerly with TDG...smooth planar surface at a constant depth. In such cases one often would like to determine the position and orientation in the plane, the depth of

  13. Ultra-sensitive Magnetic Microscopy with an Optically Pumped Magnetometer

    NASA Astrophysics Data System (ADS)

    Kim, Young Jin; Savukov, Igor

    2016-04-01

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). In addition, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.

  14. Ultra-sensitive magnetic microscopy with an optically pumped magnetometer

    SciTech Connect

    Kim, Young Jin; Savukov, Igor Mykhaylovich

    2016-04-22

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). Additionally, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.

  15. Atomic magnetometer-based ultra-sensitive magnetic microscopy

    NASA Astrophysics Data System (ADS)

    Kim, Young Jin; Savukov, Igor

    2016-03-01

    An atomic magnetometer (AM) based on lasers and alkali-metal vapor cells is currently the most sensitive non-cryogenic magnetic-field sensor. Many applications in neuroscience and other fields require high resolution, high sensitivity magnetic microscopic measurements. In order to meet this need we combined a cm-size spin-exchange relaxation-free AM with a flux guide (FG) to produce an ultra-sensitive FG-AM magnetic microscope. The FG serves to transmit the target magnetic flux to the AM thus enhancing both the sensitivity and resolution for tiny magnetic objects. In this talk, we will describe a prototype FG-AM device and present experimental and numerical tests of its sensitivity and resolution. We also demonstrate that an optimized FG-AM achieves high resolution and high sensitivity sufficient to detect a magnetic field of a single neuron in a few seconds, which would be an important milestone in neuroscience. We anticipate that this unique device can be applied to the detection of a single neuron, the detection of magnetic nano-particles, which in turn are very important for detection of target molecules in national security and medical diagnostics, and non-destructive testing.

  16. Ultra-sensitive magnetic microscopy with an optically pumped magnetometer

    DOE PAGES

    Kim, Young Jin; Savukov, Igor Mykhaylovich

    2016-04-22

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized devicemore » can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). Additionally, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.« less

  17. Ultra-sensitive Magnetic Microscopy with an Optically Pumped Magnetometer.

    PubMed

    Kim, Young Jin; Savukov, Igor

    2016-04-22

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). In addition, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.

  18. The Galileo Earth encounter - Magnetometer and allied measurements

    NASA Technical Reports Server (NTRS)

    Kivelson, M. G.; Kennel, C. F.; Mcpherron, R. L.; Russell, C. T.; Southwood, D. J.; Walker, R. J.; Khurana, K. K.; Coleman, P. J.; Hammond, C. M.; Angelopoulos, V.

    1993-01-01

    An overview of the Galileo magnetometer observations from the crossing of the tail magnetopause at an antisolar distance of close to 100 R(E) through exit into the solar wind on the dayside is presented. These measurements are linked with correlative data from ground stations and from IMP 8 which was ideally located to serve as a monitor of the solar wind upstream of the bow shock. A time line of the important geomagnetic events of the day that provides a framework for the full multiinstrument analysis of the flyby data is presented. The observations are used to investigate apsects of the relationship between magnetotail dynamics and the separate intensifications of a multiple onset substorm inferred from ground-based data. It is proposed that the signatures associated with individual substorm intensifications are localized in the dawn-to-dusk extent even at remote locations in the magnetotail, just as they are in the ionosphere, and that the tail disturbances associated with successive substorm intensifications step across the tail towards the dusk flank.

  19. Ultra-sensitive Magnetic Microscopy with an Optically Pumped Magnetometer

    PubMed Central

    Kim, Young Jin; Savukov, Igor

    2016-01-01

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). In addition, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience. PMID:27103463

  20. Usefulness of MEG magnetometer for spike detection in patients with mesial temporal epileptic focus.

    PubMed

    Enatsu, R; Mikuni, N; Usui, K; Matsubayashi, J; Taki, J; Begum, T; Matsumoto, R; Ikeda, A; Nagamine, T; Fukuyama, H; Hashimoto, N

    2008-07-15

    The present study investigated the sensitivity of magnetoencephalography (MEG) for spikes depending on sensor type in patients with mesial temporal epileptic focus. We recorded MEG in 6 patients with mesial temporal epileptic focus using two sensor types (magnetometer and gradiometer) simultaneously. The number of spikes detected and the corresponding equivalent current dipole (ECD) parameters (distance from the coordinated head center (radius), and dipole moment) were evaluated with respect to sensor type. Among 426 MEG 'consensus spikes' determined by 3 reviewers, 378 spikes satisfied the predetermined criteria for source localization. Comparing ECD parameters, spikes detected by magnetometer alone displayed a smaller radius and larger dipole moment than those detected by gradiometer alone. Spikes estimated in the mesial temporal area were more frequently detected by magnetometer alone (38.5%) than by gradiometer alone (11.5%), whereas spikes in the lateral temporal area were detected less by magnetometer alone (3.7%) than by gradiometer alone (53.9%). The present results suggest that a magnetometer is advantageous for spike detection in patients with mesial temporal epileptic focus. This also implies the higher sensitivity of magnetometer for deep sources.

  1. Digital data-acquisition system for use with a proton-precession base-station magnetometer

    SciTech Connect

    McPherron, R.L.

    1982-08-26

    At UCLA the base station magnetometer is a Scintrex MB -2 which uses a two inch wide chart record scaled to 100 nT. The magnetometer is also equipped with a digital readout. This is available in BCD format on a 37 pin connector at the back of the instrument. This reading may be recorded digitally if an appropriate data acquisition and storage system is available. The recent development of inexpensive microcomputers and audio cassette recorders provided motivation for our exploration group to develop a digital data acquisition system for the existing base station magnetometer. A block diagram of the data acquisition system is presented. The microcomputer utilizes a R6502 as the central processor. Data are entered into the computer via a 12 key keypad and are displayed on a 6 digit liquid crystal display. Data from the Scintrex base magnetometer is passed to the microcomputer via a 37 line connector. One line of this connector is used to signal the status of the internally controlled sampling circuit in the base station magnetometer. Digital data are stored temporarily in RAM memory until an output buffer is filled. When this occurs power is applied to the audio cassette tape transport mechanism and after a short delay a block of data is written onto tape. The tape interface implements the Kansas City standard which is nearly universally used for microcomputer recording on audio cassette recorders. The entire system is powered by the same 12V dc battery used by the base station magnetometer. (WHK)

  2. Low frequency magnetic field suppression in an atomic spin co-magnetometer with a large electron magnetic field

    NASA Astrophysics Data System (ADS)

    Fang, Jiancheng; Chen, Yao; Zou, Sheng; Liu, Xuejing; Hu, Zhaohui; Quan, Wei; Yuan, Heng; Ding, Ming

    2016-03-01

    In a K-Rb-21Ne co-magnetometer, the Rb electron magnetic field which is experienced by the nuclear spin is about 100 times larger than that of the K in a K-3He co-magnetometer. The large electron magnetic field which is neglected in the K-3He co-magnetometer coupled Bloch equations model is considered here in the K-Rb-21Ne co-magnetometer to study the low frequency magnetic field suppression effect. Theoretical analysis and experimental results shows that in the K-Rb-21Ne spin co-magnetometer, not only the nuclear spin but also the large electron spin magnetic field compensate the external magnetic field noise. By comparison, only the 3He nuclear spins mainly compensate the external magnetic field noise in a K-3He co-magnetometer. With this study, in addition to just increasing the magnetic field of the nuclear spins, we can suppress the magnetic field noise by increasing the density of the electron spin. We also studied how the magnetic field suppression effect relates to the scale factor of the K-Rb-21Ne co-magnetometer and we compared the scale factor with that of the K-3He co-magnetometer. Lastly, we show the sensitivity of our co-magnetometer. The magnetic field noise, the air density fluctuation noise and pumping power optimization are studied to improve the sensitivity of the co-magnetometer.

  3. 46 CFR 27.100 - What towing vessels does this part affect?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... General Provisions for Fire-Protection Measures and Fire-Suppression Equipment on Towing Vessels § 27.100... defined by 46 CFR 10.103; (iv) For response to emergency or pollution; (2) A public vessel that is both... of a fire in the engine room. (d) You must test and maintain all of the equipment required by...

  4. Influence of Tow Architecture on Compaction and Nesting in Textile Preforms

    NASA Astrophysics Data System (ADS)

    Yousaf, Z.; Potluri, P.; Withers, P. J.

    2017-04-01

    Transverse compression response of tows during processes such as vacuum infusion or autoclave curing has significant influence on resin permeability in fabrics as well as the laminate thickness, fibre volume fraction and tow orientations in the finished composite. This paper reports macro -scale deformations in dry fibre assemblies due to transverse compaction. In this study, influence of weave geometry and the presence of interlacements or stitches on the ply-level compaction as well as nesting have been investigated. 2D woven fabrics with a variety of interlacement patterns - plain, twill and sateen- as well as stitched Non-crimp (NCF) fabrics have been investigated for macro-level deformations. Compression response of single layer and multilayer stacks has been studied as a function of external pressure in order to establish nesting behaviour. It appears that the degree of individual ply compaction and degree of nesting between the plies are influenced by tow architectures. Inter-tow spacing and stitching thread thickness appears to influence the degree of nesting in non-crimp fabrics.

  5. 46 CFR 27.205 - What are the requirements for internal communication systems on towing vessels?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false What are the requirements for internal communication... requirements for internal communication systems on towing vessels? (a) You must ensure that your vessel is... required to have internal communication systems. (c) When the operating-station's engine controls and...

  6. 46 CFR 27.205 - What are the requirements for internal communication systems on towing vessels?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false What are the requirements for internal communication... requirements for internal communication systems on towing vessels? (a) You must ensure that your vessel is... required to have internal communication systems. (c) When the operating-station's engine controls and...

  7. 46 CFR 27.205 - What are the requirements for internal communication systems on towing vessels?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false What are the requirements for internal communication... requirements for internal communication systems on towing vessels? (a) You must ensure that your vessel is... required to have internal communication systems. (c) When the operating-station's engine controls and...

  8. 46 CFR 27.205 - What are the requirements for internal communication systems on towing vessels?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false What are the requirements for internal communication... requirements for internal communication systems on towing vessels? (a) You must ensure that your vessel is... required to have internal communication systems. (c) When the operating-station's engine controls and...

  9. Structural Performance of Advanced Composite Tow-Steered Shells With Cutouts

    NASA Technical Reports Server (NTRS)

    Wu, K. Chauncey; Turpin, Jason D.; Stanford, Bret K.; Martin, Robert A.

    2014-01-01

    The structural performance of two advanced composite tow-steered shells with cutouts, manufactured using an automated fiber placement system, is assessed using both experimental and analytical methods. The shells' fiber orientation angles vary continuously around their circumference from +/-10 degrees on the crown and keel, to +/-45 degrees on the sides. The raised surface features on one shell result from application of all 24 tows during each fiber placement system pass, while the second shell uses the system's tow drop/add capability to achieve a more uniform wall thickness. These unstiffened shells were previously tested in axial compression and buckled elastically. A single cutout, scaled to represent a passenger door on a commercial aircraft, is then machined into one side of each shell. The prebuckling axial stiffnesses and bifurcation buckling loads of the shells with cutouts are also computed using linear finite element structural analyses for initial comparisons with test data. When retested, large deflections were observed around the cutouts, but the shells carried an average of 92 percent of the axial stiffness, and 86 percent of the buckling loads, of the shells without cutouts. These relatively small reductions in performance demonstrate the potential for using tow steering to mitigate the adverse effects of typical design features on the overall structural performance.

  10. Structural Characterization of Advanced Composite Tow-Steered Shells with Large Cutouts

    NASA Technical Reports Server (NTRS)

    Wu, K. Chauncey; Turpin, Jason D.; Gardner, Nathaniel W.; Stanford, Bret K.; Martin, Robert A.

    2015-01-01

    The structural performance of two advanced composite tow-steered shells with large cutouts, manufactured using an automated fiber placement system, is assessed using both experimental and analytical methods. The fiber orientation angles of the shells vary continuously around their circumference from +/- 10 degrees on the crown and keel, to +/- 45 degrees on the sides. The raised surface features on one shell result from application of all 24 tows during each fiber placement system pass, while the second shell uses the tow drop/add capability of the system to achieve a more uniform wall thickness. These unstiffened shells, both without and with small cutouts, were previously tested in axial compression and buckled elastically. In this study, a single unreinforced cutout, scaled to represent a cargo door on a commercial aircraft, is machined into one side of each shell. The prebuckling axial stiffnesses and bifurcation buckling loads of these shells with large cutouts are also computed using linear finite element structural analyses for preliminary comparisons with test data. During testing, large displacements are observed around the large cutouts, but the shells maintain an average of 91 percent of the axial stiffness, and also carry 85 percent of the buckling loads, when compared to the pristine shells without cutouts. These relatively small reductions indicate that there is great potential for using tow steering to mitigate the adverse effects of large cutouts on the overall structural performance.

  11. 46 CFR 27.205 - What are the requirements for internal communication systems on towing vessels?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... required to have internal communication systems. (c) When the operating-station's engine controls and the... requirements for internal communication systems on towing vessels? (a) You must ensure that your vessel is... 46 Shipping 1 2011-10-01 2011-10-01 false What are the requirements for internal...

  12. Influence of Tow Architecture on Compaction and Nesting in Textile Preforms

    NASA Astrophysics Data System (ADS)

    Yousaf, Z.; Potluri, P.; Withers, P. J.

    2016-11-01

    Transverse compression response of tows during processes such as vacuum infusion or autoclave curing has significant influence on resin permeability in fabrics as well as the laminate thickness, fibre volume fraction and tow orientations in the finished composite. This paper reports macro -scale deformations in dry fibre assemblies due to transverse compaction. In this study, influence of weave geometry and the presence of interlacements or stitches on the ply-level compaction as well as nesting have been investigated. 2D woven fabrics with a variety of interlacement patterns - plain, twill and sateen- as well as stitched Non-crimp (NCF) fabrics have been investigated for macro-level deformations. Compression response of single layer and multilayer stacks has been studied as a function of external pressure in order to establish nesting behaviour. It appears that the degree of individual ply compaction and degree of nesting between the plies are influenced by tow architectures. Inter-tow spacing and stitching thread thickness appears to influence the degree of nesting in non-crimp fabrics.

  13. 33 CFR 164.76 - Towline and terminal gear for towing alongside and pushing ahead.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Towline and terminal gear for towing alongside and pushing ahead. 164.76 Section 164.76 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS §...

  14. 33 CFR 164.76 - Towline and terminal gear for towing alongside and pushing ahead.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Towline and terminal gear for towing alongside and pushing ahead. 164.76 Section 164.76 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS §...

  15. Tow-Steered Panels With Holes Subjected to Compression or Shear Loads

    NASA Technical Reports Server (NTRS)

    Jegley, Dawn C.; Tatting, Brian F.; Guerdal, Zafer

    2005-01-01

    Tailoring composite laminates to vary the fiber orientations within a fiber layer of a laminate to address non-uniform stress states and provide structural advantages such as the alteration of principal load paths has potential application to future low-cost, light-weight structures for commercial transport aircraft. Evaluation of this approach requires the determination of the effectiveness of stiffness tailoring through the use of curvilinear fiber paths in flat panels including the reduction of stress concentrations around the holes and the increase in load carrying capability. Panels were designed through the use of an optimization code using a genetic algorithm and fabricated using a tow-steering approach. Manufacturing limitations, such as the radius of curvature of tows the machine could support, avoidance of wrinkling of fibers and minimization of gaps between fibers were considered in the design process. Variable stiffness tow-steered panels constructed with curvilinear fiber paths were fabricated so that the design methodology could be verified through experimentation. Finite element analysis where each element s stacking sequence was accurately defined is used to verify the behavior predicted based on the design code. Experiments on variable stiffness flat panels with central circular holes were conducted with the panels loaded in axial compression or shear. Tape and tow-steered panels are used to demonstrate the buckling, post-buckling and failure behavior of elastically tailored panels. The experimental results presented establish the buckling performance improvements attainable by elastic tailoring of composite laminates.

  16. 33 CFR 155.235 - Emergency towing capability for oil tankers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Emergency towing capability for oil tankers. 155.235 Section 155.235 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL OR HAZARDOUS MATERIAL POLLUTION PREVENTION REGULATIONS...

  17. 33 CFR 155.235 - Emergency towing capability for oil tankers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Emergency towing capability for oil tankers. 155.235 Section 155.235 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL OR HAZARDOUS MATERIAL POLLUTION PREVENTION REGULATIONS...

  18. 33 CFR 155.235 - Emergency towing capability for oil tankers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Emergency towing capability for oil tankers. 155.235 Section 155.235 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION OIL OR HAZARDOUS MATERIAL POLLUTION PREVENTION REGULATIONS...

  19. 46 CFR 11.465 - Requirements for endorsements as mate (pilot) of towing vessels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 30 3 of 12 YES YES NC, GL-I (2) NEAR-COASTAL (NC) 30 12 of 30 3 of 12 YES YES GL-I (3) GREAT LAKES... near coastal routes; apprentice mate (steersman), towing vessels on Great Lakes and inland routes;...

  20. 14 CFR 61.69 - Glider and unpowered ultralight vehicle towing: Experience and training requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... airline transport pilot certificate with a category rating for powered aircraft; (2) Has logged at least... this section, has logged at least three flights as the sole manipulator of the controls of an aircraft... 17, 1967, has made and logged 10 or more flights as pilot in command of an aircraft towing a...