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Sample records for investigating high field

  1. Investigating High Field Gravity using Astrophysical Techniques

    SciTech Connect

    Bloom, Elliott D.; /SLAC

    2008-02-01

    The purpose of these lectures is to introduce particle physicists to astrophysical techniques. These techniques can help us understand certain phenomena important to particle physics that are currently impossible to address using standard particle physics experimental techniques. As the subject matter is vast, compromises are necessary in order to convey the central ideas to the reader. Many general references are included for those who want to learn more. The paragraphs below elaborate on the structure of these lectures. I hope this discussion will clarify my motivation and make the lectures easier to follow. The lectures begin with a brief review of more theoretical ideas. First, elements of general relativity are reviewed, concentrating on those aspects that are needed to understand compact stellar objects (white dwarf stars, neutron stars, and black holes). I then review the equations of state of these objects, concentrating on the simplest standard models from astrophysics. After these mathematical preliminaries, Sec. 2(c) discusses 'The End State of Stars'. Most of this section also uses the simplest standard models. However, as these lectures are for particle physicists, I also discuss some of the more recent approaches to the equation of state of very dense compact objects. These particle-physics-motivated equations of state can dramatically change how we view the formation of black holes. Section 3 focuses on the properties of the objects that we want to characterize and measure. X-ray binary systems and Active Galactic Nuclei (AGN) are stressed because the lectures center on understanding very dense stellar objects, black hole candidates (BHCs), and their accompanying high gravitational fields. The use of x-ray timing and gamma-ray experiments is also introduced in this section. Sections 4 and 5 review information from x-ray and gamma-ray experiments. These sections also discuss the current state of the art in x-ray and gamma-ray satellite experiments and

  2. Investigation of Molecular Exchange Using DEXSY with Ultra-High Pulsed Field Gradients

    SciTech Connect

    Gratz, Marcel; Galvosas, Petrik

    2008-12-05

    Diffusion exchange spectroscopy has been employed for the investigation of water exchange between different regions of a cosmetic lotion as well as for the exchange of n-pentane between the inter- and intra-crystalline space in zeolite NaX. We successfully combined this two-dimensional (2D) NMR experiment with methods for the application of ultra-high pulsed field gradients of up to 35 T/m, resulting in observation times and mixing times as short as 2 ms and 2.8 ms, respectively.

  3. Investigation of Molecular Exchange Using DEXSY with Ultra-High Pulsed Field Gradients

    NASA Astrophysics Data System (ADS)

    Gratz, Marcel; Galvosas, Petrik

    2008-12-01

    Diffusion exchange spectroscopy has been employed for the investigation of water exchange between different regions of a cosmetic lotion as well as for the exchange of n-pentane between the inter- and intra-crystalline space in zeolite NaX. We successfully combined this two-dimensional (2D) NMR experiment with methods for the application of ultra-high pulsed field gradients of up to 35 T/m, resulting in observation times and mixing times as short as 2 ms and 2.8 ms, respectively.

  4. Investigating Jeffery-Hamel flow with high magnetic field and nanoparticle by HPM and AGM

    NASA Astrophysics Data System (ADS)

    Rostami, A.; Akbari, M.; Ganji, D.; Heydari, S.

    2014-12-01

    In this study, the effects of magnetic field and nanoparticle on the Jeffery-Hamel flow are studied using two powerful analytical methods, Homotopy Perturbation Method (HPM) and a simple and innovative approach which we have named it Akbari-Ganji's Method(AGM). Comparisons have been made between HPM, AGM and Numerical Method and the acquired results show that these methods have high accuracy for different values of α, Hartmann numbers, and Reynolds numbers. The flow field inside the divergent channel is studied for various values of Hartmann number and angle of channel. The effect of nanoparticle volume fraction in the absence of magnetic field is investigated. It is necessary to represent some of the advantages of choosing the new method, AGM, for solving nonlinear differential equations as follows: AGM is a very suitable computational process and is applicable for solving various nonlinear differential equations. Moreover, in AGM by solving a set of algebraic equations, complicated nonlinear equations can easily be solved and without any mathematical operations such as integration, the solution of the problem can be obtained very simply and easily. It is notable that this solution procedure, AGM, can help students with intermediate mathematical knowledge to solve a broad range of complicated nonlinear differential equations.

  5. Physics Laboratory Investigation of Vocational High School Field Stone and Concrete Construction Techniques in the Central Java Province (Indonesia)

    ERIC Educational Resources Information Center

    Purwandari, Ristiana Dyah

    2015-01-01

    The investigation aims in this study were to uncover the observations of infrastructures and physics laboratory in vocational high school for Stone and Concrete Construction Techniques Expertise Field or Teknik Konstruksi Batu dan Beton (TKBB)'s in Purwokerto Central Java Province, mapping the Vocational High School or Sekolah Menengah Kejuruan…

  6. Investigating brain metabolism at high fields using localized 13C NMR spectroscopy without 1H decoupling.

    PubMed

    Deelchand, Dinesh Kumar; Uğurbil, Kâmil; Henry, Pierre-Gilles

    2006-02-01

    Most in vivo 13C NMR spectroscopy studies in the brain have been performed using 1H decoupling during acquisition. Decoupling imposes significant constraints on the experimental setup (particularly for human studies at high magnetic field) in order to stay within safety limits for power deposition. We show here that incorporation of the 13C label from 13C-labeled glucose into brain amino acids can be monitored accurately using localized 13C NMR spectroscopy without the application of 1H decoupling. Using LCModel quantification with prior knowledge of one-bond and multiple-bond J(CH) coupling constants, the uncertainty on metabolites concentrations was only 35% to 91% higher (depending on the carbon resonance of interest) in undecoupled spectra compared to decoupled spectra in the rat brain at 9.4 Tesla. Although less sensitive, 13C NMR without decoupling dramatically reduces experimental constraints on coil setup and pulse sequence design required to keep power deposition within safety guidelines. This opens the prospect of safely measuring 13C NMR spectra in humans at varied brain locations (not only the occipital lobe) and at very high magnetic fields above 4 Tesla. PMID:16345037

  7. Investigation of MAGSAT and TRIAD magnetometer data to provide corrective information on high-latitude external fields

    NASA Technical Reports Server (NTRS)

    Potemra, T. A. (Principal Investigator)

    1981-01-01

    The compilation of a catalog of the MAGSAT-observed high altitude disturbances is discussed and an example of contents and format is given. The graphs allow the investigation of Birkeland current signatures which are superimposed upon the main geomagnetic field. An example of a display of the MAGSAT orbital tracks in a polar geomagnetic coordinate system with the locations, flow directions, and intensities of field aligned currents shown in color is also given. The display was generated using an interactive color graphics terminal.

  8. Experimental investigation of a Ka band high power millimeter wave generator operated at low guiding magnetic field

    SciTech Connect

    Zhu Jun; Shu Ting; Zhang Jun; Li Guolin; Zhang Zehai; Fan Yuwei

    2011-05-15

    An overmoded slow wave type Ka band generator is investigated experimentally to produce high power millimeter waves in this paper. The experiments were carried out at the TORCH-01 accelerator. The produced microwave frequency was measured by dispersive line method, and the power was estimated by integrating over the radiation pattern at far field. With relatively low guiding magnetic field of 0.8 T and diode voltage and beam current of 590 kV and 5.2 kA, respectively, a 33.56 GHz millimeter wave with an output power of 320 MW was generated, and the microwave mode was quasi-TM{sub 01} mode.

  9. Theoretical investigation of the behavior of CuSe2O5 compound in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Saghafi, Z.; Jahangiri, J.; Mahdavifar, S.; Hadipour, H.; Farjami Shayesteh, S.

    2016-01-01

    Based on the analytical and numerical approaches, we investigate thermodynamic properties of CuSe2O5 compound at high magnetic fields which is a candidate for the strong intra-chain interaction in quasi one-dimensional (1D) quantum magnets. Magnetic behavior of the system can be described by the 1D spin-1/2 XXZ model in the presence of the Dzyaloshinskii-Moriya (DM) interaction. Under these circumstances, there is one quantum critical field in this compound. Below the quantum critical field the spin chain system is in the gapless Luttinger liquid (LL) regime, whereas above it one observes a crossover to the gapped saturation magnetic phase. Indications on the thermodynamic curves confirm the occurrence of such a phase transition. The main characteristics of the LL phase are gapless and spin-spin correlation functions decay algebraic. The effects of zero-temperature quantum phase transition are observed even at rather high temperatures in comparison with the counterpart compounds. In addition, we calculate the Wilson ratio in the model. The Wilson ratio at a fixed temperature remains almost independent of the field in the LL region. In the vicinity of the quantum critical field, the Wilson ratio increases and exhibits anomalous enhancement.

  10. Toward increased concentration sensitivity for continuous wave EPR investigations of spin-labeled biological macromolecules at high fields.

    PubMed

    Song, Likai; Liu, Zhanglong; Kaur, Pavanjeet; Esquiaqui, Jackie M; Hunter, Robert I; Hill, Stephen; Smith, Graham M; Fanucci, Gail E

    2016-04-01

    High-field, high-frequency electron paramagnetic resonance (EPR) spectroscopy at W-(∼94GHz) and D-band (∼140GHz) is important for investigating the conformational dynamics of flexible biological macromolecules because this frequency range has increased spectral sensitivity to nitroxide motion over the 100ps to 2ns regime. However, low concentration sensitivity remains a roadblock for studying aqueous samples at high magnetic fields. Here, we examine the sensitivity of a non-resonant thin-layer cylindrical sample holder, coupled to a quasi-optical induction-mode W-band EPR spectrometer (HiPER), for continuous wave (CW) EPR analyses of: (i) the aqueous nitroxide standard, TEMPO; (ii) the unstructured to α-helical transition of a model IDP protein; and (iii) the base-stacking transition in a kink-turn motif of a large 232nt RNA. For sample volumes of ∼50μL, concentration sensitivities of 2-20μM were achieved, representing a ∼10-fold enhancement compared to a cylindrical TE011 resonator on a commercial Bruker W-band spectrometer. These results therefore highlight the sensitivity of the thin-layer sample holders employed in HiPER for spin-labeling studies of biological macromolecules at high fields, where applications can extend to other systems that are facilitated by the modest sample volumes and ease of sample loading and geometry. PMID:26923151

  11. Toward increased concentration sensitivity for continuous wave EPR investigations of spin-labeled biological macromolecules at high fields

    NASA Astrophysics Data System (ADS)

    Song, Likai; Liu, Zhanglong; Kaur, Pavanjeet; Esquiaqui, Jackie M.; Hunter, Robert I.; Hill, Stephen; Smith, Graham M.; Fanucci, Gail E.

    2016-04-01

    High-field, high-frequency electron paramagnetic resonance (EPR) spectroscopy at W-(∼94 GHz) and D-band (∼140 GHz) is important for investigating the conformational dynamics of flexible biological macromolecules because this frequency range has increased spectral sensitivity to nitroxide motion over the 100 ps to 2 ns regime. However, low concentration sensitivity remains a roadblock for studying aqueous samples at high magnetic fields. Here, we examine the sensitivity of a non-resonant thin-layer cylindrical sample holder, coupled to a quasi-optical induction-mode W-band EPR spectrometer (HiPER), for continuous wave (CW) EPR analyses of: (i) the aqueous nitroxide standard, TEMPO; (ii) the unstructured to α-helical transition of a model IDP protein; and (iii) the base-stacking transition in a kink-turn motif of a large 232 nt RNA. For sample volumes of ∼50 μL, concentration sensitivities of 2-20 μM were achieved, representing a ∼10-fold enhancement compared to a cylindrical TE011 resonator on a commercial Bruker W-band spectrometer. These results therefore highlight the sensitivity of the thin-layer sample holders employed in HiPER for spin-labeling studies of biological macromolecules at high fields, where applications can extend to other systems that are facilitated by the modest sample volumes and ease of sample loading and geometry.

  12. The role of high-resolution geomagnetic field models for investigating ionospheric currents at low Earth orbit satellites

    NASA Astrophysics Data System (ADS)

    Stolle, Claudia; Michaelis, Ingo; Rauberg, Jan

    2016-07-01

    Low Earth orbiting geomagnetic satellite missions, such as the Swarm satellite mission, are the only means to monitor and investigate ionospheric currents on a global scale and to make in situ measurements of F region currents. High-precision geomagnetic satellite missions are also able to detect ionospheric currents during quiet-time geomagnetic conditions that only have few nanotesla amplitudes in the magnetic field. An efficient method to isolate the ionospheric signals from satellite magnetic field measurements has been the use of residuals between the observations and predictions from empirical geomagnetic models for other geomagnetic sources, such as the core and lithospheric field or signals from the quiet-time magnetospheric currents. This study aims at highlighting the importance of high-resolution magnetic field models that are able to predict the lithospheric field and that consider the quiet-time magnetosphere for reliably isolating signatures from ionospheric currents during geomagnetically quiet times. The effects on the detection of ionospheric currents arising from neglecting the lithospheric and magnetospheric sources are discussed on the example of four Swarm orbits during very quiet times. The respective orbits show a broad range of typical scenarios, such as strong and weak ionospheric signal (during day- and nighttime, respectively) superimposed over strong and weak lithospheric signals. If predictions from the lithosphere or magnetosphere are not properly considered, the amplitude of the ionospheric currents, such as the midlatitude Sq currents or the equatorial electrojet (EEJ), is modulated by 10-15 % in the examples shown. An analysis from several orbits above the African sector, where the lithospheric field is significant, showed that the peak value of the signatures of the EEJ is in error by 5 % in average when lithospheric contributions are not considered, which is in the range of uncertainties of present empirical models of the EEJ.

  13. Investigation of the process of diamagnetic particle separation in a high-gradient ordered-structure magnetic field

    NASA Astrophysics Data System (ADS)

    Kashevskii, B. É.; Kashevskii, S. É.; Prokhorov, I. V.; Zholud', A. M.

    2011-05-01

    On the basis of the model of a flow-type magnetic filter with a transversely magnetized ordered system of long ferromagnetic rods of rectangular cross section, the process of high-gradient magnetic separation of microscopic diamagnetic particles (potato starch granules of sizes 8-30 μm) from a liquid suspension has been investigated. The registered laws of change in the concentration and size distribution of particles at the suspension outlet from the filter agree with the theoretical conclusions obtained from the analysis of the magnetic field structure and thecharacter of the particle motion in the filter volume.

  14. Numerical investigation of symmetry breaking and critical behavior of the acoustic streaming field in high-intensity discharge lamps

    NASA Astrophysics Data System (ADS)

    Baumann, Bernd; Schwieger, Joerg; Wolff, Marcus; Manders, Freddy; Suijker, Jos

    2015-06-01

    For energy efficiency and material cost reduction it is preferred to drive high-intensity discharge lamps at frequencies of approximately 300 kHz. However, operating lamps at these high frequencies bears the risk of stimulating acoustic resonances inside the arc tube, which can result in low frequency light flicker and even lamp destruction. The acoustic streaming effect has been identified as the link between high frequency resonances and low frequency flicker. A highly coupled three-dimensional multiphysics model has been set up to calculate the acoustic streaming velocity field inside the arc tube of high-intensity discharge lamps. It has been found that the velocity field suffers a phase transition to an asymmetrical state at a critical acoustic streaming force. In certain respects the system behaves similar to a ferromagnet near the Curie point. It is discussed how the model allows to investigate the light flicker phenomenon. Concerning computer resources the procedure is considerably less demanding than a direct approach with a transient model.

  15. High nutrient concentration and temperature alleviated formation of large colonies of Microcystis: Evidence from field investigations and laboratory experiments.

    PubMed

    Zhu, Wei; Zhou, Xiaohua; Chen, Huaimin; Gao, Li; Xiao, Man; Li, Ming

    2016-09-15

    Correlations between Microcystis colony size and environmental factors were investigated in Meiliang Bay and Gonghu Bay of Lake Taihu (China) from 2011 to 2013. Compared with Gonghu Bay, both nutrient concentrations and Microcystis colony sizes were greater in Meiliang Bay. The median colony size (D50: 50% of the total mass of particles smaller than this size) increased from April to August and then decreased until November. In both bays, the average D50 of Microcystis colonies were <100 μm in spring, but colonies within moderate-size (100-500 μm) dominated in summer. The differences in colony size in Meiliang Bay and Gonghu Bay were probably due to horizontal drift driven by the prevailing south wind in summer. Redundancy analysis (RDA) of field data indicated that colony size was negatively related to nutrient concentrations but positively related to air temperature, suggesting that low nutrient concentrations and high air temperature promoted formation of large colonies. To validate the field survey, Microcystis colonies collected from Lake Taihu were cultured at different temperatures (15, 20, 25 and 30 °C) under high and low nutrient concentrations for 9 days. The size of Microcystis colonies significantly decreased when temperature was above 20 °C but had no significant change at 15 °C. The differences in temperature effects on colony formation shown from field and laboratory suggested that the larger colonies in summer were probably due to the longer growth period rather than the higher air temperature and light intensity. In addition, colony size decreased more significantly at high nutrient levels. Therefore, it could be concluded that high nutrient concentration and temperature may alleviate formation of large colonies of Microcystis. PMID:27262121

  16. The field-dependent shock profiles of a magnetorhelogical damper due to high impact: an experimental investigation

    NASA Astrophysics Data System (ADS)

    Kim, Hwan-Choong; Oh, Jong-Seok; Choi, Seung-Bok

    2015-02-01

    This work proposes a new damper featuring magnetorheological fluid (MR damper) and presents its field-dependent damping forces due to high impact. To achieve this goal, a large MR damper, which can produce a damping force of 100 kN at 6 A, is designed and manufactured based on the analysis of the magnetic flux intensity of the damper. After identifying the field-dependent damping force levels of the manufactured MR damper, a hydraulic horizontal shock tester is established. This shock testing system consists of a velocity generator, impact mass, shock programmer, and test mass. The MR damper is installed at the end of the wall in the shock tester and tested under four different experimental conditions. The shock profile characteristics of the MR damper due to different impact velocities are investigated at various input current levels. In addition, the inner pressure of the MR damper during impact, which depends on the input’s current level, is evaluated at two positions that can represent the pressure drop that generates the damping force of the MR damper. It is demonstrated from this impact testing that the shock profiles can be changed by the magnitude of the input current applied to the MR damper. It directly indicates that a desired shock profile can be achieved by installing the MR damper associated with appropriate control logics to adjust the magnitude of the input current.

  17. Ground vortex flow field investigation

    NASA Technical Reports Server (NTRS)

    Kuhn, Richard E.; Delfrate, John H.; Eshleman, James E.

    1988-01-01

    Flow field investigations were conducted at the NASA Ames-Dryden Flow Visualization Facility (water tunnel) to investigate the ground effect produced by the impingement of jets from aircraft nozzles on a ground board in a STOL operation. Effects on the overall flow field with both a stationary and a moving ground board were photographed and compared with similar data found in other references. Nozzle jet impingement angles, nozzle and inlet interaction, side-by-side nozzles, nozzles in tandem, and nozzles and inlets mounted on a flat plate model were investigated. Results show that the wall jet that generates the ground effect is unsteady and the boundary between the ground vortex flow field and the free-stream flow is unsteady. Additionally, the forward projection of the ground vortex flow field with a moving ground board is one-third less than that measured over a fixed ground board. Results also showed that inlets did not alter the ground vortex flow field.

  18. Nano-scale investigations of electric-dipole-layer enhanced field and thermionic emission from high current density cathodes

    NASA Astrophysics Data System (ADS)

    Vlahos, Vasilios

    Cesium iodide coated graphitic fibers and scandate cathodes are two important electron emission technologies. The coated fibers are utilized as field emitters for high power microwave sources. The scandate cathodes are promising thermionic cathode materials for pulsed power vacuum electron devices. This work attempts to understand the fundamental physical and chemical relationships between the atomic structure of the emitting cathode surfaces and the superior emission characteristics of these cathodes. Ab initio computational modeling in conjunction with experimental investigations was performed on coated fiber cathodes to understand the origin of their very low turn on electric field, which can be reduced by as much as ten-fold compared to uncoated fibers. Copious amounts of cesium and oxygen were found co-localized on the fiber, but no iodine was detected on the surface. Additional ab initio studies confirmed that cesium oxide dimers could lower the work function significantly. Surface cesium oxide dipoles are therefore proposed as the source of the observed reduction in the turn on electric field. It is also proposed that emission may be further enhanced by secondary electrons from cesium oxide during operation. Thermal conditioning of the coated cathode may be a mechanism by which surface cesium iodide is converted into cesium oxide, promoting the depletion of iodine by formation of volatile gas. Ab initio modeling was also utilized to investigate the stability and work functions of scandate structures. The work demonstrated that monolayer barium-scandium-oxygen surface structures on tungsten can dramatically lower the work function of the underlying tungsten substrate from 4.6 eV down to 1.16 eV, by the formation of multiple surface dipoles. On the basis of this work, we conclude that high temperature kinetics force conventional dispenser cathodes (barium-oxygen monolayers on tungsten) to operate in a non-equilibrium compositional steady state with higher than

  19. Magnetic fields and childhood cancer: an epidemiological investigation of the effects of high-voltage underground cables.

    PubMed

    Bunch, K J; Swanson, J; Vincent, T J; Murphy, M F G

    2015-09-01

    Epidemiological evidence of increased risks for childhood leukaemia from magnetic fields has implicated, as one source of such fields, high-voltage overhead lines. Magnetic fields are not the only factor that varies in their vicinity, complicating interpretation of any associations. Underground cables (UGCs), however, produce magnetic fields but have no other discernible effects in their vicinity. We report here the largest ever epidemiological study of high voltage UGCs, based on 52,525 cases occurring from 1962-2008, with matched birth controls. We calculated the distance of the mother's address at child's birth to the closest 275 or 400 kV ac or high-voltage dc UGC in England and Wales and the resulting magnetic fields. Few people are exposed to magnetic fields from UGCs limiting the statistical power. We found no indications of an association of risk with distance or of trend in risk with increasing magnetic field for leukaemia, and no convincing pattern of risks for any other cancer. Trend estimates for leukaemia as shown by the odds ratio (and 95% confidence interval) per unit increase in exposure were: reciprocal of distance 0.99 (0.95-1.03), magnetic field 1.01 (0.76-1.33). The absence of risk detected in relation to UGCs tends to add to the argument that any risks from overhead lines may not be caused by magnetic fields. PMID:26344172

  20. The Crustal Structure of Beira High, Central Mozambique - Combined Investigation of Wide-angle Seismic and Potential Field Data

    NASA Astrophysics Data System (ADS)

    Müller, C. O.; Schreckenberger, B.; Heyde, I.; Jokat, W.

    2015-12-01

    the lowermost velocity gradients to allow a sound interpretation of the Beira High origin. The acquired shipborne, magnetic data show a complex magnetic pattern and strong influences by the presence of lava flows and intrusions and require further investigations. We will introduce the latest results of the joint interpretation of seismic and potential field data sets.

  1. HAIC/HIWC field campaign - investigating ice microphysics in high ice water content regions of mesoscale convective systems

    NASA Astrophysics Data System (ADS)

    Leroy, Delphine; Fontaine, Emmanuel; Schwarzenboeck, Alfons; Strapp, J. Walter; Lilie, Lyle; Dezitter, Fabien; Grandin, Alice

    2015-04-01

    Despite existing research programs focusing on tropical convection, high ice water content (IWC) regions in Mesoscale Convective Systems (MCS) - potentially encountered by commercial aircraft and related to reported in-service events - remain poorly documented either because investigation of such high IWC regions was not of highest priority or because utilized instrumentation was not capable of providing accurate cloud microphysical measurements. To gather quantitative data in high IWC regions, a multi-year international HAIC/HIWC (High Altitude Ice Crystals / High Ice Water Content) field project has been designed including a first field campaign conducted out of Darwin (Australia) in 2014. The French Falcon 20 research aircraft had been equipped among others with a state-of-the-art in situ microphysics package including the IKP (isokinetic evaporator probe which provides a reference measurement of IWC and TWC), the CDP (cloud droplet spectrometer probe measuring particles in the range 2-50 µm), the 2D-S (2D-Stereo, 10-1280 µm) and PIP (precipitation imaging probe, 100-6400 µm) optical array probes. Microphysical data collection has been performed mainly at -40°C and -30°C levels, whereas little data could be sampled at -50°C and at -15C/-10°C. The study presented here focuses on ice crystal size properties, thereby analyzing in detail the 2D image data from 2D-S and PIP optical array imaging probes. 2D images recorded with 2D-S and PIP were processed in order to extract a large variety of geometrical parameters, such as maximum diameter (Dmax), 2D surface equivalent diameter (Deq), and the corresponding number particle size distribution (PSD). Using the PSD information from both probes, a composite size distribution was then built, with sizes ranging from few tens of µm to roughly 10 mm. Finally, mass-size relationships for ice crystals in tropical convection were established in terms of power laws in order to compute median mass diameters MMDmax and

  2. The MAVEN Magnetic Field Investigation

    NASA Astrophysics Data System (ADS)

    Connerney, J. E. P.; Espley, J.; Lawton, P.; Murphy, S.; Odom, J.; Oliversen, R.; Sheppard, D.

    2015-12-01

    The MAVEN magnetic field investigation is part of a comprehensive particles and fields subsystem that will measure the magnetic and electric fields and plasma environment of Mars and its interaction with the solar wind. The magnetic field instrumentation consists of two independent tri-axial fluxgate magnetometer sensors, remotely mounted at the outer extremity of the two solar arrays on small extensions ("boomlets"). The sensors are controlled by independent and functionally identical electronics assemblies that are integrated within the particles and fields subsystem and draw their power from redundant power supplies within that system. Each magnetometer measures the ambient vector magnetic field over a wide dynamic range (to 65,536 nT per axis) with a resolution of 0.008 nT in the most sensitive dynamic range and an accuracy of better than 0.05 %. Both magnetometers sample the ambient magnetic field at an intrinsic sample rate of 32 vector samples per second. Telemetry is transferred from each magnetometer to the particles and fields package once per second and subsequently passed to the spacecraft after some reformatting. The magnetic field data volume may be reduced by averaging and decimation, when necessary to meet telemetry allocations, and application of data compression, utilizing a lossless 8-bit differencing scheme. The MAVEN magnetic field experiment may be reconfigured in flight to meet unanticipated needs and is fully hardware redundant. A spacecraft magnetic control program was implemented to provide a magnetically clean environment for the magnetic sensors and the MAVEN mission plan provides for occasional spacecraft maneuvers—multiple rotations about the spacecraft x and z axes—to characterize spacecraft fields and/or instrument offsets in flight.

  3. The MAVEN Magnetic Field Investigation

    NASA Technical Reports Server (NTRS)

    Connerney, J. E. P.; Espley, J.; Lawton, P.; Murphy, S.; Odom, J.; Oliversen, R.; Sheppard, D.

    2014-01-01

    The MAVEN magnetic field investigation is part of a comprehensive particles and fields subsystem that will measure the magnetic and electric fields and plasma environment of Mars and its interaction with the solar wind. The magnetic field instrumentation consists of two independent tri-axial fluxgate magnetometer sensors, remotely mounted at the outer extremity of the two solar arrays on small extensions ("boomlets"). The sensors are controlled by independent and functionally identical electronics assemblies that are integrated within the particles and fields subsystem and draw their power from redundant power supplies within that system. Each magnetometer measures the ambient vector magnetic field over a wide dynamic range (to 65,536 nT per axis) with a quantization uncertainty of 0.008 nT in the most sensitive dynamic range and an accuracy of better than 0.05%. Both magnetometers sample the ambient magnetic field at an intrinsic sample rate of 32 vector samples per second. Telemetry is transferred from each magnetometer to the particles and fields package once per second and subsequently passed to the spacecraft after some reformatting. The magnetic field data volume may be reduced by averaging and decimation, when necessary to meet telemetry allocations, and application of data compression, utilizing a lossless 8-bit differencing scheme. The MAVEN magnetic field experiment may be reconfigured in flight to meet unanticipated needs and is fully hardware redundant. A spacecraft magnetic control program was implemented to provide a magnetically clean environment for the magnetic sensors and the MAVEN mission plan provides for occasional spacecraft maneuvers - multiple rotations about the spacecraft x and z axes - to characterize spacecraft fields and/or instrument offsets in flight.

  4. An investigation of dynamic failure events in steels using full field high-speed infrared thermography and high-speed photography

    NASA Astrophysics Data System (ADS)

    Guduru, Pradeep R.

    An infrared (IR) imaging system has been developed for measuring the temperature increase during the dynamic deformation of materials. The system consists of an 8 x 8 HgCdTe focal plane array, each with its own preamplifier. Outputs from all 64 signals are simultaneously acquired and held using a bank of track and hold amplifiers. An array of eight 8:1 multiplexers then routes the signals to eight 10MHz digitizers, acquiring data from each row of detectors in parallel. The maximum rate is one million frames per second. Crack tip temperature rise during dynamic deformation is known to alter the fracture mechanisms and consequently the fracture toughness of a material. However, no direct experimental measurements have ever been made to determine the same because of limited diagnostic tools. By transcending the existing experimental limitations, this investigation presents detailed, real time evolution of the transient crack tip temperature fields in two different steels (C300 and HY100 steels), using the 2-D high speed IR camera. The crack tip temperature rise at initiation in C300 steel was found to be about 55K. In case of HY100, which is a highly ductile steel, the crack tip temperature rise was above 200K and was seen to be a strong function of loading rate. HRR elastic-plastic singular field has been used to extract J integral evolution from the measured temperature field. An experimental investigation has been conducted to study the initiation and propagation characteristics of dynamic shear bands in C300 maraging steel. Pre-fatigued single edge notched specimens were impacted on the edge under the notch to produce shear dominated mixed mode stress fields. The optical technique of coherent gradient sensing (CGS) was employed to study the evolution of the mixed mode stress intensity factors. Simultaneously, a newly developed high speed IR camera was employed to obtain the temperature field evolution during the initiation and propagation of the shear bands. The

  5. Investigation on critical breakdown electric field of hot sulfur hexafluoride/carbon tetrafluoride mixtures for high voltage circuit breaker applications

    NASA Astrophysics Data System (ADS)

    Wang, Weizong; Murphy, Anthony B.; Rong, Mingzhe; Looe, Hui M.; Spencer, Joseph W.

    2013-09-01

    Sulfur hexafluoride (SF6) gas, widely used in high-voltage circuit breakers, has a high global warming potential and hence substitutes are being sought. The use of a mixture of carbon tetrafluoride (CF4) and SF6 is examined here. It is known that this reduces the breakdown voltage at room temperature. However, the electrical breakdown in a circuit breaker after arc interruption occurs in a hot gas environment, with a complicated species composition because of the occurrence of dissociation and other reactions. The likelihood of breakdown depends on the electron interactions with all these species. The critical reduced electric field strength (the field at which breakdown can occur, relative to the number density) of hot SF6/CF4 mixtures corresponding to the dielectric recovery phase of a high voltage circuit breaker is calculated in the temperature range from 300 K to 3500 K. The equilibrium compositions of hot SF6/CF4 mixtures under different mixing fractions were determined based on Gibbs free energy minimization. Full sets of improved cross sections for interactions between electrons and the species present are presented. The critical reduced electric field strength of these mixtures was obtained by balancing electron generation and loss mechanisms. These were evaluated using the electron energy distribution function derived from the Boltzmann transport equation under the two-term approximation. The result indicates that critical electric field strength decreases with increasing heavy-particle temperature from 1500 to 3500 K. Good agreement was found between calculations for pure hot SF6 and pure hot CF4 and experimental results and previous calculations. The addition of CF4 to SF6 was found to increase the critical reduced electric field strength for temperatures above 1500 K, indicating the potential of replacing SF6 by SF6/CF4 mixtures in high-voltage circuit breakers.

  6. Investigation of Resistive Wall Mode Stabilization Physics in High-beta Plasmas Using Applied Non-axisymmetric Fields in NSTX

    SciTech Connect

    Sontag, A. C.; Sabbagh, S. A.; Zhu, W.; Menard, J. E.; Bell, R. E.; Bialek, J. M.; Bell, M. G.; Gates, D. A.; Glasser, A. H.; LeBlanc, B. P.; Shaing, K. C.; Stutman, D.; Tritz, K. L.

    2009-06-16

    The National Spherical Torus Experiment (NSTX) offers an operational space characterized by high-beta (βt = 39%, βN > 7, βN/βno-wall N > 1.5) and low aspect ratio (A > 1.27) to leverage the plasma parameter dependences of RWM stabilization and plasma rotation damping physics giving greater confidence for extrapolation to ITER. Significant new capability for RWM research has been added to the device with the commissioning of a set of six nonaxisymmetric magnetic field coils, allowing generation of fields with dominant toroidal mode number, n, of 1–3. These coils have been used to study the dependence of resonant field amplification on applied field frequency and RWMstabilization physics by reducing the toroidal rotation profile belowits steady-state value through non-resonant magnetic braking. Modification of plasma rotation profiles shows that rotation outside q = 2.5 is not required for passive RWM stability and there is large variation in the RWM critical rotation at the q = 2 surface, both of which are consistent with distributed dissipation models.

  7. A visualization instrument to investigate the mechanical-electro properties of high temperature superconducting tapes under multi-fields.

    PubMed

    Liu, Wei; Zhang, Xingyi; Liu, Cong; Zhang, Wentao; Zhou, Jun; Zhou, YouHe

    2016-07-01

    We construct a visible instrument to study the mechanical-electro behaviors of high temperature superconducting tape as a function of magnetic field, strain, and temperature. This apparatus is directly cooled by a commercial Gifford-McMahon cryocooler. The minimum temperature of sample can be 8.75 K. A proportion integration differentiation temperature control is used, which is capable of producing continuous variation of specimen temperature from 8.75 K to 300 K with an optional temperature sweep rate. We use an external loading device to stretch the superconducting tape quasi-statically with the maximum tension strain of 20%. A superconducting magnet manufactured by the NbTi strand is applied to provide magnetic field up to 5 T with a homogeneous range of 110 mm. The maximum fluctuation of the magnetic field is less than 1%. We design a kind of superconducting lead composed of YBa2Cu3O7-x coated conductor and beryllium copper alloy (BeCu) to transfer DC to the superconducting sample with the maximum value of 600 A. Most notably, this apparatus allows in situ observation of the electromagnetic property of superconducting tape using the classical magnetic-optical imaging. PMID:27475594

  8. A visualization instrument to investigate the mechanical-electro properties of high temperature superconducting tapes under multi-fields

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Zhang, Xingyi; Liu, Cong; Zhang, Wentao; Zhou, Jun; Zhou, YouHe

    2016-07-01

    We construct a visible instrument to study the mechanical-electro behaviors of high temperature superconducting tape as a function of magnetic field, strain, and temperature. This apparatus is directly cooled by a commercial Gifford-McMahon cryocooler. The minimum temperature of sample can be 8.75 K. A proportion integration differentiation temperature control is used, which is capable of producing continuous variation of specimen temperature from 8.75 K to 300 K with an optional temperature sweep rate. We use an external loading device to stretch the superconducting tape quasi-statically with the maximum tension strain of 20%. A superconducting magnet manufactured by the NbTi strand is applied to provide magnetic field up to 5 T with a homogeneous range of 110 mm. The maximum fluctuation of the magnetic field is less than 1%. We design a kind of superconducting lead composed of YBa2Cu3O7-x coated conductor and beryllium copper alloy (BeCu) to transfer DC to the superconducting sample with the maximum value of 600 A. Most notably, this apparatus allows in situ observation of the electromagnetic property of superconducting tape using the classical magnetic-optical imaging.

  9. The crustal structure of Beira High, central Mozambique-Combined investigation of wide-angle seismic and potential field data

    NASA Astrophysics Data System (ADS)

    Mueller, Christian Olaf; Jokat, Wilfried; Schreckenberger, Bernd

    2016-06-01

    The timing and geometry of the initial Gondwana break-up between Africa and East Antarctica is still poorly known due to missing information about the continent-ocean boundaries along the rifted margins. In this context, the Beira High off central Mozambique forms a critical geological feature of uncertain crustal fabric. Based on new wide-angle seismic and potential field data across Beira High a P-wave velocity model, supported by amplitude and gravity modelling, provides constraints on the crustal composition of this area. In the Mozambique Basin mainly normal oceanic crust of 5.5-7 km thickness with velocities of 6.5-7.0 km/s in the lower crust is present. A sharp transition towards Beira High marks the continent-ocean boundary. Here the crust thickens to 23 km at maximum. A small velocity-depth gradient and a constant increase in velocity with basal velocities of maximum 7.0 km/s are in good agreement with typical velocities of continental crust and continental fragments. The density model indicates the existence of felsic material in greater depths and supports a fabric of stretched, but highly intruded continental crust below Beira High. A gradual decrease in crustal thickness characterizes the transition towards the Mozambican shelf area. Here, in the Zambezi Delta Depression 12 km of sediments cover the underlying 7 km thick crust. The presence of a high-velocity lower crustal body with velocities of 7.1-7.4 km/s indicates underplated, magmatic material in this part of the profile. However, the velocity structure in the shelf area allows no definite interpretation because of the experimental setup. Thus, the crustal nature below the Zambezi Delta and consequently the landward position of the continent-ocean boundary remains unknown. The difference in stretching below the margins of Beira High suggests the presence of different thinning directions and a rift jump during the early rifting stage.

  10. High Field Solid-State NMR Spectroscopy Investigation of (15)N-Labeled Rosette Nanotubes: Hydrogen Bond Network and Channel-Bound Water.

    PubMed

    Fenniri, Hicham; Tikhomirov, Grigory A; Brouwer, Darren H; Bouatra, Souhaila; El Bakkari, Mounir; Yan, Zhimin; Cho, Jae-Young; Yamazaki, Takeshi

    2016-05-18

    (15)N-labeled rosette nanotubes were synthesized and investigated using high-field solid-state NMR spectroscopy, X-ray diffraction, atomic force microscopy, and electron microscopy. The results established the H-bond network involved in the self-assembly of the nanostructure as well as bound water molecules in the nanotube's channel. PMID:27141817

  11. Investigation of Mechanical Activation on Li-N-H Systems Using 6Li Magic Angle Spinning Nuclear Magnetic Resonance at Ultra-High Field

    SciTech Connect

    Hu, Jian Zhi; Kwak, Ja Hun; Yang, Zhenguo; Osborn, William; Markmaitree, Tippawan; Shaw, Leonard D.

    2008-07-15

    Abstract The significantly enhanced spectral resolution in the 6Li MAS NMR spectra of Li-N-H systems at ultra-high field of 21.1 tesla is exploited, for the first time, to study the detailed electronic and chemical environmental changes associated with mechanical activation of Li-N-H system using high energy balling milling. Complementary to ultra-high field studies, the hydrogen discharge dynamics are investigated using variable temperature in situ 1H MAS NMR at 7.05 tesla field. The significantly enhanced spectral resolution using ultra-high filed of 21.1 tesla was demonstrated along with several major findings related to mechanical activation, including the upfield shift of the resonances in 6Li MAS spectra induced by ball milling, more efficient mechanical activation with ball milling at liquid nitrogen temperature than with ball milling at room temperature, and greatly enhanced hydrogen discharge exhibited by the liquid nitrogen ball milled samples.

  12. The Giotto magnetic field investigation

    NASA Technical Reports Server (NTRS)

    Neubauer, F. M.; Musmann, G.; Acuna, M. H.; Burlaga, L. F.; Ness, N. F.; Mariani, F.; Wallis, M.; Ungstrup, E.; Schmidt, H.

    1983-01-01

    The Giotto spacecraft will carry sensors for investigating the interplanetary magnetic field while en route and the interaction between the solar wind magnetoplasma and Halley's Comet neutral gas outflow during close approach. Giotto will carry an outboard biaxial fluxgate system and inboard electronics. The instrumentation draws 1.2 kW and weighs 1.31 kg. Sampling rates will be 28/sec during close encounter, covering selectable ranges from 16 nT to 65,535 nT. In-flight calibration techniques are under development to ensure magnetic cleanliness will be obtained. Measurements are also planned of the inbound bow shock, the magnetosheath and the cometary ionopause. The data will be collected as close as 1000 km from the comet surface.

  13. Damage and loss assessment on rubber trees caused by typhoon based on high-precision remote sensing data and field investigation

    NASA Astrophysics Data System (ADS)

    Li, Jian; Fang, Weihua; Tan, Chenyan

    2016-04-01

    Forest dynamics are highly relevant to land hydrology, climate, carbon budget and biodiversity. Damage and loss assessment of forest caused by typhoon is essential to the understanding of ecosystem variations. Combination of high-precision remote sensing data and field investigation is critical to the assessment of forest damage loss. In this study, high-precision remote sensing data prior to and after typhoon from IKONOS, QuickBird, unmanned aerial vehicle (UAV) are used for identifying rubber tree disturbance. The ground truth data of rubber tree damage collected through field investigation are used to verify and compare the results. Taken the forest damage induced by typhoon Rammasun (201409) in Hainan as an example, 5 damage types (overthrown, trunk snapped below 2m, trunk snapped above 2m, half-overthrown, and sheared) of rubber trees are clearly interpreted compared with field investigation results. High-precision remote sensing data is then applied to other areas to evaluate the forest damage severity. At last, rubber tree damage severity is investigated with other typhoon hazard factors such as wind, topography, soil and precipitation.

  14. Numerical investigation of the high Reynolds number 3D flow field generated by a self-propelling manta ray

    NASA Astrophysics Data System (ADS)

    Pederzani, Jean-Noel; Haj-Hariri, Hossein

    2012-11-01

    An embedded-boundary (or cut-cell) method for complex geometry with moving boundaries is used to solve the three dimensional Navier-Stokes equation around a self-propelling manta swimming at moderately high Reynolds numbers. The motion of the ray is prescribed using a kinematic model fitted to actual biological data. The dependence of thrust production mechanism on Strouhal and Reynolds numbers is investigated. The vortex core structures are accurately plotted and a correlation between wake structures and propulsive performance is established. This insight is critical in understanding the key flow features that a bio-inspired autonomous vehicle should reproduce in order to swim efficiently. The solution method is implemented, on a block-structured Cartesian grid using a cut-cell approach enabling the code to correctly evaluate the wall shear-stress, a key feature necessary at higher Reynolds. To enhance computational efficiency, a parallel adaptive mesh refinement technique is used. The present method is validated against published experimental results. Supported by ONR MURI.

  15. Investigations on the magnetic field coupling of automotive high voltage systems to determine relevant parameters for an EMR-optimized designing

    NASA Astrophysics Data System (ADS)

    Krause, David; John, Werner; Weigel, Robert

    2016-03-01

    The implementation of electrical drive trains in modern vehicles is a new challenge for EMC development. This contribution depicts a variety of investigations on magnetic field coupling of automotive high-voltage (HV) systems in order to fulfil the requirements of an EMR-optimized designing. The theoretical background is discussed within the scope of current analysis, including the determination of current paths and spectral behaviour. It furthermore presents models of shielded HV cables with particular focus on the magnetic shielding efficiency. Derived findings are validated by experimental measurements of a state-of-the-art demonstrator on system level. Finally EMC design rules are discussed in the context of minimized magnetic fields.

  16. Field investigation of keyblock stability

    SciTech Connect

    Yow, J.L. Jr.

    1985-04-01

    Discontinuities in a rock mass can intersect an excavation surface to form discrete blocks (keyblocks) which can be unstable. This engineering problem is divided into two parts: block identification, and evaluation of block stability. One stable keyblock and thirteen fallen keyblocks were observed in field investigations at the Nevada Test Site. Nine blocks were measured in detail sufficient to allow back-analysis of their stability. Measurements included block geometry, and discontinuity roughness and compressive strength. Back-analysis correctly predicted stability or failure in all but two cases. These two exceptions involved situations that violated the stress assumptions of the stability calculations. Keyblock faces correlated well with known joint set orientations. The effect of tunnel orientation on keyblock frequency was apparent. Back-analysis of physical models successfully predicted block pullout force for two-dimensional models of unit thickness. Two-dimensional (2D) and three-dimensional (3D) analytic models for the stability of simple pyramidal keyblocks were examined. Calculated stability is greater for 3D analyses than for 2D analyses. Calculated keyblock stability increases with larger in situ stress magnitudes, larger lateral stress ratios, and larger shear strengths. Discontinuity stiffness controls block displacement more strongly than it does stability itself. Large keyblocks are less stable than small ones, and stability increases as blocks become more slender. Rock mass temperature decreases reduce the confining stress magnitudes and can lead to failure. The pattern of stresses affecting each block face explains conceptually the occurrence of pyramidal keyblocks that are truncated near their apex.

  17. Polypyrrole nanostructures and their field emission investigations

    NASA Astrophysics Data System (ADS)

    Harpale, Kashmira; More, Mahendra A.; Koinkar, Pankaj M.; Patil, Sandip S.; Sonawane, Kishor M.

    2015-03-01

    Polypyrrole (PPy) nanostructures have been synthesized on indium doped tin oxide (ITO) substrates by a facile electrochemical route employing cyclic voltammetry (CV) mode. The morphology of the PPy thin films was observed to be influenced by the monomer concentration. Furthermore, FTIR revealed formation of electrically conducting state of PPy. Field emission investigations of the PPy nanostructures were carried out at base pressure of 1×10-8mbar. The values of turn-on field, corresponding to emission current density of 1 μA/cm2 were observed to be 0.6, 1.0 and 1.2 V/μm for the PPy films characterized with rod-like, cauliflower and granular morphology, respectively. In case of PPy nanorods maximum current density of 1.2 mA/cm2 has been drawn at electric field of 1 V/μm. The low turn on field, extraction of very high emission current density at relatively lower applied field and good emission stability propose the PPy nanorods as a promising material for field emission based devices.

  18. High volume-high value usage of flue gas desulfurization (FGD) by-products in underground mines: Phase 2 -- Field investigations. Quarterly report, October 1--December 31, 1997

    SciTech Connect

    1998-08-01

    The field investigation phase of the project was essentially completed when grout placed into auger holes at the Lodestar Energy mine site during Summer 1997 was sampled. Mining had proceeded to a point where the strata overlying the coal was completely removed, thus exposing the grout-filled auger holes. All of the auger holes contained either grout from these experiments or shale that in-filled the non-grouted holes during the process of clearing the top surface of the coal. Eleven grouted holes were sampled, utilizing hammers and chisels, for physical (strength) testing, as well as chemical, mineralogical, and microscopical analysis. Upon arrival at the laboratory, moisture contents, densities, and void ratios were obtained before disturbing the samples, and after strength testing. Representative samples of each grout were then cut into flat-sided prisms, with a height:width ratio {approx}2, to be used for testing of unconfined compressive strength. In summary, all of the grouts had very good mechanical strength, ranging from 1000 psi to 2250 psi. The lowest compressive strength was recorded on a bed ash-based grout.

  19. Cobalt(II) "scorpionate" complexes as models for cobalt-substituted zinc enzymes: electronic structure investigation by high-frequency and -field electron paramagnetic resonance spectroscopy.

    PubMed

    Krzystek, J; Swenson, Dale C; Zvyagin, S A; Smirnov, Dmitry; Ozarowski, Andrew; Telser, Joshua

    2010-04-14

    A series of complexes of formula Tp(R,R')CoL, where Tp(R,R'-) = hydrotris(3-R,5-R'-pyrazol-1-yl)borate ("scorpionate") anion (R = tert-butyl, R' = H, Me, 2'-thienyl (Tn), L = Cl(-), NCS(-), NCO(-), N(3)(-)), has been characterized by electronic absorption spectroscopy in the visible and near-infrared (near-IR) region and by high-frequency and -field electron paramagnetic resonance (HFEPR). Reported here are also crystal structures of seven members of the series that have not been reported previously: R' = H, L = NCO(-), N(3)(-); R' = Me, L = Cl(-), NCS(-), NCO(-), N(3)(-); R' = Tn, L = Cl(-), NCS(-). These include a structure for Tp(t-Bu,Me)CoCl different from that previously reported. All of the investigated complexes contain a four-coordinate cobalt(II) ion (3d(7)) with approximate C(3v) point group symmetry about the metal ion and exhibit an S = (3)/(2) high-spin ground state. The use of HFEPR allows extraction of the full set of intrinsic S = (3)/(2) spin Hamiltonian parameters (D, E, and g values). The axial zero-field splitting parameter, D, for all investigated Tp(R,R')CoL complexes is always positive, a fact not easily determined by other methods. However, the magnitude of this parameter varies widely: 2.4 cm(-1) field parameters for these complexes following the angular overlap model (AOM). This description of electronic structure and bonding in pseudotetrahedral cobalt(II) complexes can enhance the understanding of similar sites in metalloproteins, specifically cobalt-substituted zinc enzymes. PMID:20329727

  20. Investigation of Aluminum Site Changes of Dehydrated Zeolite H-Beta during a Rehydration Process by High Field Solid State NMR

    SciTech Connect

    Zhao, Zhenchao; Xu, Suochang; Hu, Mary Y.; Bao, Xinhe; Peden, Charles HF; Hu, Jian Z.

    2015-01-22

    Aluminum site changes for dehydrated H-Beta zeolite during rehydration process are systematically investigated by ²⁷Al MAS and MQ MAS NMR at high magnetic fields up to 19.9 T. Benefiting from the high magnetic field, more detailed information is obtained from the considerably broadened and overlapped spectra of dehydrated H-beta zeolite. Dynamic changes of aluminum sites are demonstrated during rehydration process. In completely dehydrated H-Beta, invisible aluminum can reach 29%. The strength of quadrupole interactions for framework aluminum sites decreases gradually during water adsorption processes. The number of extra-framework aluminum (EFAL) species, i.e., penta- (34 ppm) and octa- (4 ppm) coordinated aluminum atoms rises initially with increasing water adsorption, and finally change into either tetra-coordinated framework or extra-framework aluminum in saturated water adsorption samples, with the remaining octa-coordinated aluminum lying at 0 and -4 ppm, respectively. Quantitative ²⁷Al MAS NMR analysis combined with ¹H MAS NMR indicates that some active EFAL species formed during calcination can reinsert into the framework during this hydration process. The assignment of aluminum at 0 ppm to EFAL cation and -4 ppm to framework aluminum is clarified for H-Beta zeolite.

  1. Progress with field investigations at Stripa

    SciTech Connect

    Witherspoon, P.A.; Cook, N.G.W.; Gale, J.E.

    1980-02-01

    It is generally agreed that the most practicable method of isolating nuclear wastes from the biosphere is by deep burial in suitable geologic formations. Such burial achieves a high degree of physical isolation but raises questions concerning the rate at which some of these wastes may return to the biosphere through transport by groundwater. Any suitable repository site will be disturbed first by the excavation of the repository and second by the thermal pulse caused by the radioactive decay of the wastes. To assess the effectiveness of geologic isolation it is necessary to develop the capability of predicting the response of a rock mass to such a thermal pulse. Ultimately, this requires field measurements at depths below surface and in media representative of those likely to be encountered at an actual repository. Access to a granitic rock mass adjacent to a defunct iron ore mine at Stripa in Sweden at a depth of about 350 m below surface has provided a unique opportunity to conduct a comprehensive suite of hydrological and thermo-mechanical experiments under such conditions virtually without delay. The results of these field tests have shown the importance of geologic structure and the functional dependence of the thermo-mechanical properties on temperature in developing a valid predictive model. The results have also demonstrated the vital importance of being able to carry out large scale investigations in a field test facility.

  2. High-field side scrape-off layer investigation: scaling of the power e-folding width and impurity screening behavior in near-double null configurations

    NASA Astrophysics Data System (ADS)

    Labombard, B.; Kuang, A.; Brunner, D.; Mumgaard, R.; Terry, J.; Hughes, J. W.; Walk, J.; Chilenski, M.; Lin, Y.; Marmar, E.; Wallace, G.; Whyte, D.; Wolfe, S.; Wukitch, S.; Reinke, M.

    2015-11-01

    Fluctuation-induced transport measured on the C-Mod high-field side (HFS) scrape-off layer (SOL) is extremely low; n, T profiles there become very sharp in near-double null configurations and, unlike on the low-field side (LFS), no far SOL ``shoulders'' are seen. In single-null discharges, this transport asymmetry drives near-sonic parallel flows. A strong impurity screening behavior is also evident - 6x higher N puff rate on the HFS compared to LFS produces the same core N content. It has been proposed that future tokamaks should exploit this remarkable behavior - locate all RF actuators and close-fitting wall structures on the HFS and employ near-double-null topologies, for example. C-Mod is presently investigating this physics more fully: (1) How does the HFS power e-folding width scale with plasma current, ~ 1/Ip as seen for the LFS? (2) Does the favorable screening behavior extend to balanced-double null behavior where the HFS SOL flows become stagnant, or must some unbalance be required? Latest experimental results will be presented. Supported by USDoE agreement DE-FC02-99ER54512.

  3. Spray features in the near field of a flow-blurring injector investigated by high-speed visualization and time-resolved PIV

    NASA Astrophysics Data System (ADS)

    Jiang, Lulin; Agrawal, Ajay K.

    2015-05-01

    In a flow-blurring (FB) injector, atomizing air stagnates and bifurcates at the gap upstream of the injector orifice. A small portion of the air penetrates into the liquid supply line to create a turbulent two-phase flow. Pressure drop across the injector orifice causes air bubbles to expand and burst thereby disintegrating the surrounding liquid into a fine spray. In previous studies, we have demonstrated clean and stable combustion of alternative liquid fuels, such as biodiesel, straight vegetable oil and glycerol by using the FB injector without requiring fuel pre-processing or combustor hardware modification. In this study, high-speed visualization and time-resolved particle image velocimetry (PIV) techniques are employed to investigate the FB spray in the near field of the injector to delineate the underlying mechanisms of atomization. Experiments are performed using water as the liquid and air as the atomizing gas for air to liquid mass ratio of 2.0. Flow visualization at the injector exit focused on a field of view with physical dimensions of 2.3 mm × 1.4 mm at spatial resolution of 7.16 µm per pixel, exposure time of 1 µs, and image acquisition rate of 100 k frames per second. Image sequences illustrate mostly fine droplets indicating that the primary breakup by FB atomization likely occurs within the injector itself. A few larger droplets appearing mainly at the injector periphery undergo secondary breakup by Rayleigh-Taylor instabilities. Time-resolved PIV is applied to quantify the droplet dynamics in the injector near field. Plots of instantaneous, mean, and root-mean-square droplet velocities are presented to reveal the secondary breakup process. Results show that the secondary atomization to produce fine and stable spray is complete within a few diameters from the injector exit. These superior characteristics of the FB injector are attractive to achieve clean combustion of different fuels in practical systems.

  4. Hurricane Ike: Field Investigation Survey (Invited)

    NASA Astrophysics Data System (ADS)

    Ewing, L.

    2009-12-01

    Hurricane Ike made landfall at 2:10 a.m. on September 13, 2008, as a Category 2 hurricane. The eye of the hurricane crossed over the eastern end of Galveston Island and a large region of the Texas and Louisiana coast experienced extreme winds, waves and water levels, resulting in large impacts from overtopping, overwash, wind and wave forces and flooding. Major damage stretched from Freeport to the southwest and to Port Arthur to the northeast. The effects of the hurricane force winds were felt well inland in Texas and Louisiana and the storm continued to the interior of the US, causing more damage and loss of life. Through the support of the Coasts, Oceans, Ports and Rivers Institute (COPRI) of the American Society of Civil Engineers (ASCE) a team of 14 coastal scientists and engineers inspected the upper Texas coast in early October 2008. The COPRI team surveyed Hurricane Ike’s effects on coastal landforms, structures, marinas, shore protection systems, and other infrastructure. Damages ranges from very minor to complete destruction, depending upon location and elevation. Bolivar Peninsula, to the right of the hurricane path, experienced severe damage and three peninsula communities were completely destroyed. Significant flood and wave damage also was observed in Galveston Island and Brazoria County that were both on the left side of the hurricane path. Beach erosion and prominent overwash fans were observed throughout much of the field investigation area. The post-storm damage survey served to confirm expected performance under extreme conditions, as well as to evaluate recent development trends and conditions unique to each storm. Hurricane Ike confirmed many previously reported observations. One of the main conclusions from the inspection of buildings was that elevation was a key determinant for survival. Elevation is also a major factor in the stability and effectiveness of shore protection. The Galveston Seawall was high enough to provide protection from

  5. High volume-high value usage of flue gas desulfurization (FGD) by-products in underground mines: Phase 2 -- Field investigations. Quarterly report, January 1--March 31, 1998

    SciTech Connect

    1998-09-01

    The factors that control the strength of FBC ash grout were the focus of work during this quarter. Samples were prepared at different water contents and placed into cylindrical PVC molds. At specified curing intervals, the grout cylinders were subjected to unconfined compressive strength testing as per procedures described in previous reports. Chemical, mineralogical, and microscopical analyses were also conducted on the samples. It was found that higher curing temperatures significantly increase the strength gain rate of the FBC ash grout, in agreement with earlier results. As expected, water content also exerts a strong influence on the strength of the grout. The compressive strength data obtained for the laboratory-prepared samples are in excellent agreement with strength data obtained on grout placed in auger holes during the field demonstrations. The data also indicate that the field samples suffered negligible deterioration over the course of the curing period in the auger holes. Analysis of the laboratory prepared grout samples using XRD revealed a mineralogy similar to the field samples. A correspondence between ettringite abundance and compressive strength was observed only during grout curing. The formation of minerals such as ettringite is apparently a good indication that curing reactions are progressing and that the grout strength is increasing, but mineral distribution by itself does not explain or predict final strength. The microscopy data, in combination with geotechnical and XRD data, suggest that the strength of the grout is largely a function of the density of an amorphous (or finely crystalline) material that comprises the majority of the cured grout. Therefore, an increase in density of this material results in an increase in grout strength.

  6. The Electron Losses and Fields Investigation

    NASA Astrophysics Data System (ADS)

    Bingley, L.; Angelopoulos, V.; Caron, R.; Zarifian, A.; Miller, J.; Gildemeister, A.; Schoen, B.; Tsai, E.; Berger, S.; Zhang, F.; Subramanian, A.; Chung, M.; Runov, A.; Cruce, P. R.

    2015-12-01

    The Electron Losses and Fields Investigation (ELFIN), is a joint NASA/NSF funded project at the University of California, Los Angeles focusing on eliminating the current deficit in the understanding of the innate physical processes behind geomagnetic storms. Set to launch in 2017, the mission takes advantage of a 3U+ CubeSat design to reduce cost and complexity traditionally associated with a space weather mission of this kind. This mission seeks to quantify the precipitation of relativistic electrons from the radiation belts using a pair of energetic particle detectors (EPDs). The spacecraft will also fly a fluxgate magnetometer (FGM) for determining the pitch angle distribution of the particles, which in conjunction with the EPDs will provide insight to the mechanisms responsible for their loss. Electromagnetic Ion Cyclotron (EMIC) waves are thought to be a significant contributor to the precipitation of electrons trapped in the magnetosphere; however without direct measurement to verify the exact energy range of the particles with high angular resolution, the precise role of these waves is as yet undetermined. ELFIN is unique as it is the first spacecraft that will perform direct pitch angle measurements of the high-energy electrons at the region in the ionosphere where the particles are being lost. Together with correlative measurements from THEMIS, Van Allen Probes and the upcoming ERG mission, ELFIN will provide a unique dataset of magnetospheric wave-particle interactions that will be able to contribute to a marked increase in the fidelity of current space weather models.

  7. Performance Investigation of Proteomic Identification by HCD/CID Fragmentations in Combination with High/Low-Resolution Detectors on a Tribrid, High-Field Orbitrap Instrument.

    PubMed

    Tu, Chengjian; Li, Jun; Shen, Shichen; Sheng, Quanhu; Shyr, Yu; Qu, Jun

    2016-01-01

    The recently-introduced Orbitrap Fusion mass spectrometry permits various types of MS2 acquisition methods. To date, these different MS2 strategies and the optimal data interpretation approach for each have not been adequately evaluated. This study comprehensively investigated the four MS2 strategies: HCD-OT (higher-energy-collisional-dissociation with Orbitrap detection), HCD-IT (HCD with ion trap, IT), CID-IT (collision-induced-dissociation with IT) and CID-OT on Orbitrap Fusion. To achieve extensive comparison and identify the optimal data interpretation method for each technique, several search engines (SEQUEST and Mascot) and post-processing methods (score-based, PeptideProphet, and Percolator) were assessed for all techniques for the analysis of a human cell proteome. It was found that divergent conclusions could be made from the same dataset when different data interpretation approaches were used and therefore requiring a relatively fair comparison among techniques. Percolator was chosen for comparison of techniques because it performs the best among all search engines and MS2 strategies. For the analysis of human cell proteome using individual MS2 strategies, the highest number of identifications was achieved by HCD-OT, followed by HCD-IT and CID-IT. Based on these results, we concluded that a relatively fair platform for data interpretation is necessary to avoid divergent conclusions from the same dataset, and HCD-OT and HCD-IT may be preferable for protein/peptide identification using Orbitrap Fusion. PMID:27472422

  8. Performance Investigation of Proteomic Identification by HCD/CID Fragmentations in Combination with High/Low-Resolution Detectors on a Tribrid, High-Field Orbitrap Instrument

    PubMed Central

    Shen, Shichen; Sheng, Quanhu; Shyr, Yu; Qu, Jun

    2016-01-01

    The recently-introduced Orbitrap Fusion mass spectrometry permits various types of MS2 acquisition methods. To date, these different MS2 strategies and the optimal data interpretation approach for each have not been adequately evaluated. This study comprehensively investigated the four MS2 strategies: HCD-OT (higher-energy-collisional-dissociation with Orbitrap detection), HCD-IT (HCD with ion trap, IT), CID-IT (collision-induced-dissociation with IT) and CID-OT on Orbitrap Fusion. To achieve extensive comparison and identify the optimal data interpretation method for each technique, several search engines (SEQUEST and Mascot) and post-processing methods (score-based, PeptideProphet, and Percolator) were assessed for all techniques for the analysis of a human cell proteome. It was found that divergent conclusions could be made from the same dataset when different data interpretation approaches were used and therefore requiring a relatively fair comparison among techniques. Percolator was chosen for comparison of techniques because it performs the best among all search engines and MS2 strategies. For the analysis of human cell proteome using individual MS2 strategies, the highest number of identifications was achieved by HCD-OT, followed by HCD-IT and CID-IT. Based on these results, we concluded that a relatively fair platform for data interpretation is necessary to avoid divergent conclusions from the same dataset, and HCD-OT and HCD-IT may be preferable for protein/peptide identification using Orbitrap Fusion. PMID:27472422

  9. The magnetic field investigation on Cluster

    NASA Technical Reports Server (NTRS)

    Balogh, A.; Cowley, S. W. H.; Southwood, D. J.; Musmann, G.; Luhr, H.; Neubauer, F. M.; Glassmeier, K.-H.; Riedler, W.; Heyn, M. F.; Acuna, M. H.

    1988-01-01

    The magnetic field investigation of the Cluster four-spacecraft mission is designed to provide intercalibrated measurements of the B magnetic field vector. The instrumentation and data processing of the mission are discussed. The instrumentation is identical on the four spacecraft. It consists of two triaxial fluxgate sensors and of a failure tolerant data processing unit. The combined analysis of the four spacecraft data will yield such parameters as the current density vector, wave vectors, and the geometry and structure of discontinuities.

  10. Inlet flow field investigation. Part 1: Transonic flow field survey

    NASA Technical Reports Server (NTRS)

    Yetter, J. A.; Salemann, V.; Sussman, M. B.

    1984-01-01

    A wind tunnel investigation was conducted to determine the local inlet flow field characteristics of an advanced tactical supersonic cruise airplane. A data base for the development and validation of analytical codes directed at the analysis of inlet flow fields for advanced supersonic airplanes was established. Testing was conducted at the NASA-Langley 16-foot Transonic Tunnel at freestream Mach numbers of 0.6 to 1.20 and angles of attack from 0.0 to 10.0 degrees. Inlet flow field surveys were made at locations representative of wing (upper and lower surface) and forebody mounted inlet concepts. Results are presented in the form of local inlet flow field angle of attack, sideflow angle, and Mach number contours. Wing surface pressure distributions supplement the flow field data.

  11. High field superconducting magnets

    NASA Technical Reports Server (NTRS)

    Hait, Thomas P. (Inventor); Shirron, Peter J. (Inventor)

    2011-01-01

    A superconducting magnet includes an insulating layer disposed about the surface of a mandrel; a superconducting wire wound in adjacent turns about the mandrel to form the superconducting magnet, wherein the superconducting wire is in thermal communication with the mandrel, and the superconducting magnet has a field-to-current ratio equal to or greater than 1.1 Tesla per Ampere; a thermally conductive potting material configured to fill interstices between the adjacent turns, wherein the thermally conductive potting material and the superconducting wire provide a path for dissipation of heat; and a voltage limiting device disposed across each end of the superconducting wire, wherein the voltage limiting device is configured to prevent a voltage excursion across the superconducting wire during quench of the superconducting magnet.

  12. High field gradient particle accelerator

    DOEpatents

    Nation, John A.; Greenwald, Shlomo

    1989-01-01

    A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle.

  13. High field gradient particle accelerator

    DOEpatents

    Nation, J.A.; Greenwald, S.

    1989-05-30

    A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications is disclosed. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle. 10 figs.

  14. Field investigation of the drift shadow

    USGS Publications Warehouse

    Su, G.W.; Kneafsey, T.J.; Ghezzehei, T.A.; Cook, P.J.; Marshall, B.D.

    2006-01-01

    The "Drift Shadow" is defined as the relatively drier region that forms below subsurface cavities or drifts in unsaturated rock. Its existence has been predicted through analytical and numerical models of unsaturated flow. However, these theoretical predictions have not been demonstrated empirically to date. In this project we plan to test the drift shadow concept through field investigations and compare our observations to simulations. Based on modeling studies we have an identified a suitable site to perform the study at an inactive mine in a sandstone formation. Pretest modeling studies and preliminary characterization of the site are being used to develop the field scale tests.

  15. FIELD INVESTIGATIONS OF THE DRIFT SHADOW

    SciTech Connect

    G. W. Su, T. J. Kneafsey, T. A. Ghezzehei, B. D. Marshall, and P. J. Cook

    2006-01-15

    The ''Drift Shadow'' is defined as the relatively drier region that forms below subsurface cavities or drifts in unsaturated rock. Its existence has been predicted through analytical and numerical models of unsaturated flow. However, these theoretical predictions have not been demonstrated empirically to date. In this project they plan to test the drift shadow concept through field investigations and compare our observations to simulations. Based on modeling studies they have an identified suitable site to perform the study at an inactive mine in a sandstone formation. Pretest modeling studies and preliminary characterization of the site are being used to develop the field scale tests.

  16. Investigation of the Hall Effect in Rectangular Quantum Wells with a Perpendicular Magnetic Field in the Presence of a High-Frequency Electromagnetic Wave

    NASA Astrophysics Data System (ADS)

    Bau, Nguyen Quang; Hoi, Bui Dinh

    2014-11-01

    The Hall effect is theoretically studied in a rectangular quantum well (RQW) with infinite barriers subjected to a crossed dc electric field and magnetic field (the magnetic field is oriented perpendicularly to the barriers) in the presence of a high-frequency electromagnetic wave (EMW). By using the quantum kinetic equation for electrons interacting with acoustic phonons at low temperatures, we obtain analytical expressions for the conductivity tensor as well as the Hall coefficient (HC). Numerical results for the AlGaN/GaN RQW show the Shubnikov-de Haas (SdH) oscillations in the magnetoresistance (MR) whose period does not depend on the temperature and amplitude decreases with increasing temperature. In the presence of the EMW, the MR shows maxima at Ω/ωc = 1, 2, 3, … and minima at Ω/ωc = 3/2, 5/2, 7/2, … (Ω and ωc are the EMW and the cyclotron frequencies, respectively), and with increasing of the EMW amplitude the MR approaches zero. Obtained results are in accordance with recent experimental data and in good agreement with other theories in two-dimensional (2D) electron systems. The results for the HC show a saturation of the HC as the magnetic field or the EMW frequency increases. Furthermore, in the region of large magnetic field the HC depends weakly on the well-width.

  17. Rydberg EIT in High Magnetic Field

    NASA Astrophysics Data System (ADS)

    Ma, Lu; Anderson, David; Miller, Stephanie; Raithel, Georg

    2016-05-01

    We present progress towards an all-optical approach for measurements of strong magnetic fields using electromagnetically induced transparency (EIT) with Rydberg atoms in an atomic vapor. Rydberg EIT spectroscopy is a promising technique for the development of atom-based, calibration- and drift-free technology for high magnetic field sensing. In this effort, Rydberg EIT is employed to spectroscopically investigate the response of Rydberg atoms exposed to strong magnetic fields, in which Rydberg atoms are in the strong-field regime. In our setup, two neodymium block magnets are used to generate fields of about 0.8 Tesla, which strongly perturb the atoms. Information on the field strength and direction is obtained by a comparison of experimental spectra with calculated spectral maps. Investigations of magnetic-field inhomogeneities and other decoherence sources will be discussed.

  18. Electronic structure of four-coordinate C3v nickel(II) scorpionate complexes: investigation by high-frequency and -field electron paramagnetic resonance and electronic absorption spectroscopies.

    PubMed

    Desrochers, Patrick J; Telser, Joshua; Zvyagin, S A; Ozarowski, Andrew; Krzystek, J; Vicic, David A

    2006-10-30

    A series of complexes of formula TpNiX, where Tp*- = hydrotris(3,5-dimethylpyrazole)borate and X = Cl, Br, I, has been characterized by electronic absorption spectroscopy in the visible and near-infrared (NIR) region and by high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy. The crystal structure of TpNiCl has been previously reported; that for TpNiBr is given here: space group = Pmc2(1), a = 13.209(2) A, b = 8.082(2) A, c = 17.639(4) A, alpha = beta = gamma = 90 degrees , Z = 4. TpNiX contains a four-coordinate nickel(II) ion (3d8) with approximate C3v point group symmetry about the metal and a resulting S = 1 high-spin ground state. As a consequence of sizable zero-field splitting (zfs), TpNiX complexes are "EPR silent" with use of conventional EPR; however, HFEPR allows observation of multiple transitions. Analysis of the resonance field versus the frequency dependence of these transitions allows extraction of the full set of spin Hamiltonian parameters. The axial zfs parameter for TpNiX displays pronounced halogen contributions down the series: D = +3.93(2), -11.43(3), -22.81(1) cm(-1), for X = Cl, Br, I, respectively. The magnitude and change in sign of D observed for TpNiX reflects the increasing bromine and iodine spin-orbit contributions facilitated by strong covalent interactions with nickel(II). These spin Hamiltonian parameters are combined with estimates of 3d energy levels based on the visible-NIR spectra to yield ligand-field parameters for these complexes following the angular overlap model (AOM). This description of electronic structure and bonding in a pseudotetrahedral nickel(II) complex can enhance the understanding of similar sites in metalloproteins, both native nickel enzymes and nickel-substituted zinc enzymes. PMID:17054352

  19. Investigation of high-temperature, igneous-related hydraulic fracturing as a reservoir control in the Blackburn and Grant Canyon/Bacon Flat oil fields, Nevada

    SciTech Connect

    Hulen, J.B.

    1991-01-01

    Research in progress to evaluate natural, igenous-related hydrothermal fracturing as a reservoir control in two eastern Nevada oil fields has revealed evidence of a far more comprehensive role for moderate- to high-temperature hydrothermal systems in Basin-and-Range oil-reservoir evolution. Fluid-inclusion and petrographic studies have shown that (now) oil-bearing dolomite breccias of the Blackburn field (Pine Valley, Eureka County) were formed when overpressured, magmatically-heated, high-temperature (>350{degrees}C) hydrothermal brines explosively ruptured their host rocks; similar studies of texturally identical breccias of the Grant Canyon/Bacon Flat field (Railroad Valley, Nye County) so far do not support such an explosive origin. At Grant Canyon, however, hydrothermal, breccia-cementing quartz hosts primary oil, aqueous/oil, and aqueous fluid inclusions (homogenization temperature = 120{degrees}C) which document a direct geothermal connection for oil migration and entrapment. Moreover, at both Blackburn and Grant Canyon/Bacon Flat, the oil reservoirs are top- and side-sealed by hydrothermally altered Tertiary ignimbrites and epiclastic rocks. Contemporary geothermal activity is also apparent at grant Canyon/Bacon Flat, where subsurface water temperatures reach 171{degrees}C, and at Blackburn, above which a petroleum-providing hot spring issues at a temperature of 90{degrees}C. We suggest that in the Basin and Range province, hydrothermal systems may have: (1) matured oil from otherwise submature source rocks; (2) transported oil to ultimate entrapment sites by convection in moderate-to high-temperature fluids; and (3) sealed reservoir traps through hydrothermal alteration of overlying Tertiary caprocks. 69 refs., 11 figs., 1 tab.

  20. Spectroscopic investigation of the spatiotemporal dynamics of an electric field in plasma of a beam-type high-voltage discharge in helium

    SciTech Connect

    Demkin, V. P.; Mel'nichuk, S. V.

    2015-02-15

    In the present work, a method of determining the spatiotemporal characteristics of the electric field strength in an accelerating gap and a plasma flare of a beam-type high-voltage pulsed discharge in He at moderate pressure is presented. The method is based on spectroscopic data on the Stark splitting of π-components of He 2P–4Q transitions; Q = D(4921.93 Å), F(4920.35 Å) in the near-cathode region of the discharge and on the spatiotemporal characteristics of intensities of He(2s{sup 1}S–3p{sup 1}P{sup 0}) spectral lines with λ = 5015 Å and He{sup +}(3d–4f) spectral lines with λ = 4685 Å measured experimentally and calculated from the data of statistical simulation of the electron kinetics by the Monte Carlo method. The shape and strength of the electric field of the space charge in the interelectrode gap and the drift region of the discharge are estimated. It is demonstrated that the electric field created by the current pulse of uncompensated space charge in the near-anode region changes the discharge regime and causes degradation of the electron beam in the plasma flare. It is established that the flux of secondary electrons from the drift region to the anode has significant effect on the radiation intensity distribution in this region of the discharge.

  1. Planar dipolar polymer brush: field theoretical investigations

    NASA Astrophysics Data System (ADS)

    Mahalik, Jyoti; Kumar, Rajeev; Sumpter, Bobby

    2015-03-01

    Physical properties of polymer brushes bearing monomers with permanent dipole moments and immersed in a polar solvent are investigated using self-consistent field theory (SCFT). It is found that mismatch between the permanent dipole moments of the monomer and the solvent plays a significant role in determining the height of the polymer brush. Sign as well as magnitude of the mismatch determines the extent of collapse of the polymer brush. The mismatch in the dipole moments also affects the force-distance relations and interpenetration of polymers in opposing planar brushes. In particular, an attractive force between the opposing dipolar brushes is predicted for stronger mismatch parameter. Furthermore, effects of added monovalent salt on the structure of dipolar brushes will also be presented. This investigation highlights the significance of dipolar interactions in affecting the physical properties of polymer brushes. Csmd division, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831, USA.

  2. A modular designed ultra-high-vacuum spin-polarized scanning tunneling microscope with controllable magnetic fields for investigating epitaxial thin films.

    PubMed

    Wang, Kangkang; Lin, Wenzhi; Chinchore, Abhijit V; Liu, Yinghao; Smith, Arthur R

    2011-05-01

    A room-temperature ultra-high-vacuum scanning tunneling microscope for in situ scanning freshly grown epitaxial films has been developed. The core unit of the microscope, which consists of critical components including scanner and approach motors, is modular designed. This enables easy adaptation of the same microscope units to new growth systems with different sample-transfer geometries. Furthermore the core unit is designed to be fully compatible with cryogenic temperatures and high magnetic field operations. A double-stage spring suspension system with eddy current damping has been implemented to achieve ≤5 pm z stability in a noisy environment and in the presence of an interconnected growth chamber. Both tips and samples can be quickly exchanged in situ; also a tunable external magnetic field can be introduced using a transferable permanent magnet shuttle. This allows spin-polarized tunneling with magnetically coated tips. The performance of this microscope is demonstrated by atomic-resolution imaging of surface reconstructions on wide band-gap GaN surfaces and spin-resolved experiments on antiferromagnetic Mn(3)N(2)(010) surfaces. PMID:21639503

  3. Investigation of the Structure and Active Sites of TiO2 Nanorod Supported VOx Catalysts by High-Field and Fast-Spinning 51V MAS NMR

    SciTech Connect

    Hu, Jian Z.; Xu, Suochang; Li, Weizhen; Hu, Mary Y.; Deng, Xuchu; Dixon, David A.; Vasiliu, Monica; Craciun, Raluca; Wang, Yong; Bao, Xinhe; Peden, Charles HF

    2015-07-02

    Supported VOx/TiO2-Rod catalysts were studied by 51V MAS NMR at high field using a sample spinning rate of 55 kHz. The superior spectral resolution allows for the observation of at least five vanadate species. The assignment of these vanadate species was carried out by quantum mechanical calculations of 51V NMR chemical shifts of model V-surface structures. Methanol oxidative dehydrogenation (ODH) was used to establish the correlation between the reaction rate and the various surface V-sites. It is found that monomeric V-species dominated the catalyst at low vanadium loadings with two peaks observed at about -502 and -529 ppm. V-dimers with two bridged oxygen appeare at about -555 ppm. Vanadate dimers and polyvanadates connected by one bridged oxygen atom between two adjacent V atoms resonate at about -630 ppm. A positive correlation is found between the V-dimers related to the -555 ppm peak and the ODH rate while a better correlation is obtained by including monomeric contributions. This result indicates that surface V-dimers related to the -555 ppm peak are the major active sites for ODH reaction despite mono-V species are more catalytic active but their relative ratios are decreased dramatically at high V-loadings. Furthermore, a portion of the V-species is found invisible. In particular, the level of such invisibility increases with decreased level of V-loading, suggesting the existence of paramagnetic V-species at the surface.

  4. Nonlinear diffusion waves in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Oreshkin, V. I.; Chaikovsky, S. A.; Labetskaya, N. A.; Datsko, I. M.; Rybka, D. V.; Ratakhin, N. A.; Khishchenko, K. V.

    2015-11-01

    The nonlinear diffusion of a magnetic field and the large-scale instabilities arising upon an electrical explosion of conductors in a superstrong (2-3 MG) magnetic field were investigated experimentally on the MIG high-current generator (up to 2.5 peak current, 100 ns current rise time). It was observed that in the nonlinear stage of the process, the wavelength of thermal instabilities (striations) increased with a rate of 1.5-3 km/s.

  5. Low temperature, high magnetic field investigations of the nature of magnetism in the molecular semiconductor β- cobalt phthalocyanine (C32H16CoN8)

    NASA Astrophysics Data System (ADS)

    Wang (王正君), Zhengjun; Lee, M.; Choi, E. S.; Poston, J.; Seehra, M. S.

    2016-06-01

    Results from detailed investigations of the magnetic properties of a powder sample of β-CoPc for the temperatures T=0.4 K to 300 K and in magnetic fields H up to 90 kOe are reported. X-ray diffraction confirmed the β-phase and scanning electron microscopy showed plate-like morphology of the sample. For T>3 K, the data of magnetic susceptibility χ vs. T fit the Curie-Weiss (CW) law yielding θ=-2.5 K, μ=2.16 μB per Co2+ and g=2.49 for spin S=1/2 of the low spin-state of Co2+. However for T<3 K, the χ vs. T data deviates from the CW law yielding a peak in χ at Tmax=1.9 K. It is shown that the χ vs. T data from 0.4 K to 300 K fits well with the predictions of the Bonner-Fisher (BF) model for S=1/2 Heisenberg linear chain antiferromagnet with the Co2+-Co2+ exchange J/kB = -1.5 K (Ĥ=-2J Σ Si•Si+1). The data of magnetization M vs. H at T=1 K agrees with the predictions of the BF model with J/kB=-1.5 K, yielding saturation magnetization MS=12.16 emu/g above 60 kOe corresponding to complete alignment of the spins.

  6. Persistence in STEM: An investigation of the relationship between high school experiences in science and mathematics and college degree completion in STEM fields

    NASA Astrophysics Data System (ADS)

    Maltese, Adam V.

    While the number of Bachelor's degrees awarded annually has nearly tripled over the past 40 years (NSF, 2008), the same cannot be said for degrees in the STEM (science, technology, engineering and mathematics) fields. The Bureau of Labor Statistics projects that by the year 2014 the combination of new positions and retirements will lead to 2 million job openings in STEM (BLS, 2005). Thus, the research questions I sought to answer with this study were: (1)What are the most common enrollment patterns for students who enter into and exit from the STEM pipeline during high school and college? (2) Controlling for differences in student background and early interest in STEM careers, what are the high school science and mathematics classroom experiences that characterize student completion of a college major in STEM? Using data from NELS:88 I analyzed descriptive statistics and completed logistic regressions to gain an understanding of factors related to student persistence in STEM. Approximately 4700 students with transcript records and who participated in all survey rounds were included in the analyses. The results of the descriptive analysis demonstrated that most students who went on to complete majors in STEM completed at least three or four years of STEM courses during high school, and enrolled in advanced high school mathematics and science courses at higher rates. At almost every pipeline checkpoint indicators of the level of coursework and achievement were significant in predicting student completion of a STEM degree. The results also support previous research that showed demographic variables have little effect on persistence once the sample is limited to those who have the intrinsic ability and desire to complete a college degree. The most significant finding is that measures of student interest and engagement in science and mathematics were significant in predicting completion of a STEM degree, above and beyond the effects of course enrollment and performance

  7. Emplacement and geochemical evolution of highly evolved syenites investigated by a combined structural and geochemical field study: The lujavrites of the Ilímaussaq complex, SW Greenland

    NASA Astrophysics Data System (ADS)

    Ratschbacher, Barbara C.; Marks, Michael A. W.; Bons, Paul D.; Wenzel, Thomas; Markl, Gregor

    2015-08-01

    Structural mapping and the combined study of magmatic to solid-state deformation textures and mineral compositions in highly evolved nepheline syenites (lujavrites) of the alkaline to peralkaline Ilímaussaq complex (South Greenland) reveal detailed insight into the emplacement and geochemical evolution of the melts they crystallized from. Based on magmatic to solid-state flow textures such as foliations and lineations, we propose that the investigated rock sequence forms a sill-like structure with a steep feeder zone that flattens out over a short distance and intrudes into less evolved overlying units as sub-horizontal sheets by roof uplift. Systematic compositional variation of early-magmatic eudialyte-group minerals (EGM) in the investigated rock sequence monitors the geochemical evolution of the lujavrite-forming melt(s). The chlorine contents of EGM decrease successively upwards within the rock sequence, which probably indicates a successive increase of water activity during differentiation, consistent with a change from sodic pyroxene (aegirine) to sodic amphibole (arfvedsonite) in the mineral assemblage. Both REE contents and Fe/Mn ratios of EGM are promising differentiation indicators, which increase and decrease, respectively, upwards within the sequence due to fractional crystallization. This closed-system evolution is interrupted by a shift towards less evolved melt compositions in one lujavrite unit, for which we assume magma recharge. Our study demonstrates the strength of a combined structural and petrological approach to understand the petrogenesis of an igneous body in more detail and highlights their close connection.

  8. A high-resolution field-emission-gun, scanning electron microscope investigation of anisotropic hydrogen decrepitation in Nd-Fe-B-based sintered magnets

    SciTech Connect

    Soderznik, Marko; McGuiness, Paul; Zuzek-Rozman, Kristina; Kobe, Spomenka; Skulj, Irena; Yan Gaolin

    2010-05-15

    In this investigation commercial magnets based on (Nd,Dy){sub 14}(Fe,Co){sub 79}B{sub 7} were prepared by a conventional powder-metallurgy route with a degree of alignment equal to {approx}90% and then exposed to hydrogen at a pressure of 1 bar. The magnets, in the form of cylinders, were observed to decrepitate exclusively from the ends. High-resolution electron microscopy was able to identify the presence of crack formation within the Nd{sub 2}Fe{sub 14}B grains, with the cracks running parallel to the c axis of these grains. Based on the concentration profile for hydrogen in a rare-earth transition-metal material, it is clear that the presence of hydrogen-induced cracks running perpendicular to the ends of the magnet provides for a much more rapidly progressing hydrogen front in this direction than from the sides of the magnet. This results in the magnet exhibiting a macroscopic tendency to decrepitate from the poles of the magnet toward the center. This combination of microstructural modification via particle alignment as part of the sintering process and direct observation via high-resolution electron microscopy has led to a satisfying explanation for the anisotropic hydrogen-decrepitation effect.

  9. The Giotto magnetic-field investigation

    NASA Technical Reports Server (NTRS)

    Neubauer, F. M.; Acuna, M. H.; Burlaga, L. F.; Franke, B.; Gramkow, B.; Mariani, F.; Musmann, G.; Ness, N. F.; Schmidt, H. U.; Terenzi, T.

    1986-01-01

    The objectives of the Giotto magnetometer experiment are the investigation of the interaction between Comet Halley and the solar wind 0.9 AU from the Sun, to within 500 km of the cometary nucleus, and the study of the interplanetary magnetic field. The instrumentation consists of a triaxial and a separate biaxial system of fluxgate sensors of the ring-core type, the associated analog electronics and a digital processor. The measuring ranges of + or 1 16 up to + or - 65536 nT are digitized by a 12-bit analog-to-digital converter. Memory modes allow the bridging of gaps in telemetry coverage of up to 10 days. Because of the dust hazard near closest approach, a magnetometer boom could not be included in the spacecraft design. The magnetic contamination problem was attacked by the use of two magnetometers and by a magnetic-cleanliness program. In-flight results show that the instrument is working flawlessly, though magnetic-contamination problems remain.

  10. FIELD INVESTIGATION OF THE DRIFT SHADOW

    SciTech Connect

    G.W. Su; T.J. Kneafsey

    2006-02-01

    A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rock mass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming the existence of the drift shadow have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow--and the corresponding hydrological process at the Hazel-Atlas silica-sand mine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rock mass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content using a gravimetric technique, as well as analyzed for chemistry. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift

  11. Field Investigation of the Drift Shadow

    NASA Astrophysics Data System (ADS)

    Su, G. W.; Kneafsey, T. J.; Ghezzehei, T. A.; Marshall, B. D.; Cook, P. J.

    2005-12-01

    A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rock mass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming its existence have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow and the corresponding hydrological process at the Hazel-Atlas silica-sand mine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine Formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rock mass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content and chemical constituents. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift. Tensiometers, electrical resistance probes, neutron probes, and

  12. Strain sensors for high field pulse magnets

    SciTech Connect

    Martinez, Christian; Zheng, Yan; Easton, Daniel; Farinholt, Kevin M; Park, Gyuhae

    2009-01-01

    In this paper we present an investigation into several strain sensing technologies that are being considered to monitor mechanical deformation within the steel reinforcement shells used in high field pulsed magnets. Such systems generally operate at cryogenic temperatures to mitigate heating issues that are inherent in the coils of nondestructive, high field pulsed magnets. The objective of this preliminary study is to characterize the performance of various strain sensing technologies at liquid nitrogen temperatures (-196 C). Four sensor types are considered in this investigation: fiber Bragg gratings (FBG), resistive foil strain gauges (RFSG), piezoelectric polymers (PVDF), and piezoceramics (PZT). Three operational conditions are considered for each sensor: bond integrity, sensitivity as a function of temperature, and thermal cycling effects. Several experiments were conducted as part of this study, investigating adhesion with various substrate materials (stainless steel, aluminum, and carbon fiber), sensitivity to static (FBG and RFSG) and dynamic (RFSG, PVDF and PZT) load conditions, and sensor diagnostics using PZT sensors. This work has been conducted in collaboration with the National High Magnetic Field Laboratory (NHMFL), and the results of this study will be used to identify the set of sensing technologies that would be best suited for integration within high field pulsed magnets at the NHMFL facility.

  13. Field investigation of the drift shadow

    SciTech Connect

    Su, Grace W.; Kneafsey, Timothy J.; Ghezzehei, Teamrat A.; Marshall, Brian D.; Cook, Paul J.

    2005-09-08

    A drift shadow is an area immediately beneath an undergroundvoidthat, in theory, will be relatively drier than the surrounding rockmass. Numerical and analytical models of water flow through unsaturatedrock predict the existence of a drift shadow, but field tests confirmingits existence have yet to be performed. Proving the existence of driftshadows and understanding their hydrologic and transport characteristicscould provide a better understanding of how contaminants move in thesubsurface if released from waste emplacement drifts such as the proposednuclear waste repository at Yucca Mountain, Nevada. We describe the fieldprogram that will be used to investigate the existence of a drift shadowand the corresponding hydrological process at the Hazel-Atlas silica-sandmine located at the Black Diamond Mines Regional Preserve in Antioch,California. The location and configuration of this mine makes it anexcellent site to observe and measure drift shadow characteristics. Themine is located in a porous sandstone unit of the Domengine Formation, anapproximately 230 meter thick series of interbedded Eocene-age shales,coals, and massive-bedded sandstones. The mining method used at the minerequired the development of two parallel drifts, one above the other,driven along the strike of the mined sandstone stratum. Thisconfiguration provides the opportunity to introduce water into the rockmass in the upper drift and to observe and measure its flow around theunderlying drift. The passive and active hydrologic tests to be performedare described. In the passive method, cores will be obtained in a radialpattern around a drift and will be sectioned and analyzed for in-situwater content and chemical constituents. With the active hydrologic test,water will be introduced into the upper drift of the two parallel driftsand the flow of the water will be tracked as it passes near the bottomdrift. Tensiometers, electrical resistance probes, neutron probes, andground penetrating radar may be

  14. Cellulose Structural Polymorphism in Plant Primary Cell Walls Investigated by High-Field 2D Solid-State NMR Spectroscopy and Density Functional Theory Calculations.

    PubMed

    Wang, Tuo; Yang, Hui; Kubicki, James D; Hong, Mei

    2016-06-13

    The native cellulose of bacterial, algal, and animal origins has been well studied structurally using X-ray and neutron diffraction and solid-state NMR spectroscopy, and is known to consist of varying proportions of two allomorphs, Iα and Iβ, which differ in hydrogen bonding, chain packing, and local conformation. In comparison, cellulose structure in plant primary cell walls is much less understood because plant cellulose has lower crystallinity and extensive interactions with matrix polysaccharides. Here we have combined two-dimensional magic-angle-spinning (MAS) solid-state nuclear magnetic resonance (solid-state NMR) spectroscopy at high magnetic fields with density functional theory (DFT) calculations to obtain detailed information about the structural polymorphism and spatial distributions of plant primary-wall cellulose. 2D (13)C-(13)C correlation spectra of uniformly (13)C-labeled cell walls of several model plants resolved seven sets of cellulose chemical shifts. Among these, five sets (denoted a-e) belong to cellulose in the interior of the microfibril while two sets (f and g) can be assigned to surface cellulose. Importantly, most of the interior cellulose (13)C chemical shifts differ significantly from the (13)C chemical shifts of the Iα and Iβ allomorphs, indicating that plant primary-wall cellulose has different conformations, packing, and hydrogen bonding from celluloses of other organisms. 2D (13)C-(13)C correlation experiments with long mixing times and with water polarization transfer revealed the spatial distributions and matrix-polysaccharide interactions of these cellulose structures. Celluloses f and g are well mixed chains on the microfibril surface, celluloses a and b are interior chains that are in molecular contact with the surface chains, while cellulose c resides in the core of the microfibril, outside spin diffusion contact with the surface. Interestingly, cellulose d, whose chemical shifts differ most significantly from those of

  15. Field investigation of rooting potential in sorghum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The differential influence of root systems on plant development under field conditions is very difficult. A field experiment was devised using three different row spacings (101,152 and 203 cm ) to screen sorghum germplasm for rooting potential based on the relative ability to explore additional soil...

  16. High Performance Field Reversed Configurations

    NASA Astrophysics Data System (ADS)

    Binderbauer, Michl

    2014-10-01

    The field-reversed configuration (FRC) is a prolate compact toroid with poloidal magnetic fields. FRCs could lead to economic fusion reactors with high power density, simple geometry, natural divertor, ease of translation, and possibly capable of burning aneutronic fuels. However, as in other high-beta plasmas, there are stability and confinement concerns. These concerns can be addressed by introducing and maintaining a significant fast ion population in the system. This is the approach adopted by TAE and implemented for the first time in the C-2 device. Studying the physics of FRCs driven by Neutral Beam (NB) injection, significant improvements were made in confinement and stability. Early C-2 discharges had relatively good confinement, but global power losses exceeded the available NB input power. The addition of axially streaming plasma guns, magnetic end plugs as well as advanced surface conditioning leads to dramatic reductions in turbulence driven losses and greatly improved stability. As a result, fast ion confinement significantly improved and allowed for build-up of a dominant fast particle population. Under such appropriate conditions we achieved highly reproducible, long-lived, macroscopically stable FRCs with record lifetimes. This demonstrated many beneficial effects of large orbit particles and their performance impact on FRCs Together these achievements point to the prospect of beam-driven FRCs as a path toward fusion reactors. This presentation will review and expand on key results and present context for their interpretation.

  17. Hyperfine structure and magnetic properties of Zn doped Co{sub 2}Z hexaferrite investigated by high-field Mössbauer spectroscopy

    SciTech Connect

    Lim, Jung Tae; Kim, Chul Sung

    2015-05-07

    The polycrystalline samples of Ba{sub 3}Co{sub 2−x}Zn{sub x}Fe{sub 24}O{sub 41} (x = 0.0, 0.5, 1.0, 1.5, and 2.0) were synthesized by the standard solid-state-reaction method. Based on the XRD patterns analyzed by Rietveld refinement, the structure was determined to be single-phased hexagonal with space group of P6{sub 3}/mmc. With increasing Zn ion concentration, the unit cell volume (V{sub u}) of samples was increased, as the sites of Fe{sup 3+} ions changed from tetrahedral to octahedral sites. We have obtained zero-field Mössbauer spectra of all samples at various temperatures ranging from 4.2 to 750 K. The measured spectra below T{sub C} were analyzed with six distinguishable sextets due to the superposition of ten-sextets for Fe sites, corresponding to the Z-type hexagonal ferrite. Also, the hyperfine field (H{sub hf}) and electric quadrupole shift (E{sub Q}) have shown abrupt changes around spin transition temperature (T{sub S}). In addition, Mössbauer spectra of all samples at 4.2 K were taken with an applied field ranging from 0 to 50 kOe, which indicates the decrease in the canting angle between applied field and H{sub hf} of samples with increasing Zn concentration.

  18. Hyperfine structure and magnetic properties of Zn doped Co2Z hexaferrite investigated by high-field Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Lim, Jung Tae; Kim, Chul Sung

    2015-05-01

    The polycrystalline samples of Ba3Co2-xZnxFe24O41 (x = 0.0, 0.5, 1.0, 1.5, and 2.0) were synthesized by the standard solid-state-reaction method. Based on the XRD patterns analyzed by Rietveld refinement, the structure was determined to be single-phased hexagonal with space group of P63/mmc. With increasing Zn ion concentration, the unit cell volume (Vu) of samples was increased, as the sites of Fe3+ ions changed from tetrahedral to octahedral sites. We have obtained zero-field Mössbauer spectra of all samples at various temperatures ranging from 4.2 to 750 K. The measured spectra below TC were analyzed with six distinguishable sextets due to the superposition of ten-sextets for Fe sites, corresponding to the Z-type hexagonal ferrite. Also, the hyperfine field (Hhf) and electric quadrupole shift (EQ) have shown abrupt changes around spin transition temperature (TS). In addition, Mössbauer spectra of all samples at 4.2 K were taken with an applied field ranging from 0 to 50 kOe, which indicates the decrease in the canting angle between applied field and Hhf of samples with increasing Zn concentration.

  19. Coordinated use of ground-based auroral and high-precision LEO magnetic and electric field measurements to investigate auroral electrodynamics

    NASA Astrophysics Data System (ADS)

    Donovan, E.

    2008-12-01

    There are now dozens of sensitive All-Sky Imagers (ASIs) deployed in networks spanning latitudes from the subauroral zone into the polar cap and many hours of magnetic local time. These new networks are collecting data with unprecedented spatial coverage and temporal resolution and in numerous scientifically interesting wavelength ranges. As well, direct satellite overflights of ground-based images that were once rare occurrences are becoming increasingly commonplace. This talk will focus on the scientific opportunities afforded by the integrated use of ground-based auroral images and magnetic and electric field data from existing and planned LEO missions including CHAMP, Oersted, and Swarm. These opportunities include exploring the relationship between field-aligned current and Poynting flux and different types of aurora, as well as reducing spatio-temporal ambiguity in the in situ measurements.

  20. Investigating the QED vacuum with ultra-intense laser fields

    NASA Astrophysics Data System (ADS)

    King, B.; Di Piazza, A.

    2014-05-01

    In view of the increasingly stronger available laser fields it is becoming feasible to employ them to probe the nonlinear dielectric properties of the vacuum as predicted by quantum electrodynamics (QED) and to test QED in the presence of intense laser beams. First, we discuss vacuum-polarization effects that arise in the collision of a high-energy proton beam with a strong laser field. In addition, we investigate the process of light-by-light diffraction mediated by the virtual electron-positrons of the vacuum. A strong laser beam "diffracts" a probe laser field due to vacuum polarization effects, and changes its polarization. This change of the polarization is shown to be in principle measurable. Also, the possibility of generating harmonics by exploiting vacuum-polarization effects in the collision in vacuum of two ultra-strong laser beams is discussed. Moreover, when two strong parallel laser beams collide with a probe electromagnetic field, each photon of the probe may interact through the "polarized" quantum vacuum with the photons of the other two fields. Analogously to "ordinary" double-slit set-ups involving matter, the vacuum-scattered probe photons produce a diffraction pattern, which is the envisaged observable to measure the quantum interaction between the probe and strong field photons. We have shown that the diffraction pattern becomes visible in a few operating hours, if the strong fields have an intensity exceeding 1024W/cm2.

  1. A semi-empirical self-consistent-field hartree—fock crystal-orbital investigation on highly puckered porphyrinatonickel(II) backbones

    NASA Astrophysics Data System (ADS)

    Böhm, Michael C.

    1984-06-01

    The band structure of a highly puckered, saddle-shaped prophyrinatonickel(II) polymer with large inter-deck separations has been studied by means of a semi-empirical INDO crystal-orbital approach. The oxidized material belongs to the class of organic metals with narrow bands that lead to strongly correlated hopping motions of injected charge carriers

  2. An investigation into the utilization of HCMM thermal data for the descrimination of volcanic and Eolian geological units. [Craters of the Moon volcanic field, Idaho; San Francisco volcanic field, Arizona; High Desert, California; and the Cascade Range, California and Oregon

    NASA Technical Reports Server (NTRS)

    Head, J. W., III (Principal Investigator)

    1982-01-01

    Analysis of HCMM data shows that the resolution provided by the thermal data is inadequate to permit the identification of individual lava flows within the volcanic test sites. Thermal data of southern California reveals that dune complexes at Kelso and Algodomes are found to be too small to permit adequate investigation of their structure. As part of the study of the San Francisco volcanic field, marked variations in the thermal properties of the region between Flagstaff and the Utah State border were observed. Several well-defined units within the Grand Canyon and the Colorado Plateau were recognized and appear to be very suitable for analysis with HCMM, SEASAT and LANDSAT images. Although individual volcanic constructs within the Cascade Range are too small to permit detailed characterization with the thermal data, the regional volcano/tectonic setting offers a good opportunity for comparing the possible thermal distinction between this area and sedimentary fold belts such as those found in the eastern United States. Strong intra-regional variations in vegetation cover were also tentatively identified for the Oregon test site.

  3. Field investigation to assess nutrient emission from paddy field to surface water in river catchment

    NASA Astrophysics Data System (ADS)

    Kogure, Kanami; Aichi, Masaatsu; Zessner, Matthias

    2015-04-01

    TD water can be sampled for infiltrating water measurement. We installed monitoring wells to measure ground water level and water quality. Inflow, outflow, flooding water, infiltrating water, and ground water were measured and sampled. Regarding to parameters, temperature, pH, EC, DO and COD, main ions were measured to understand characteristic of water quality and transformation processes. Inorganic forms of nitrogen and phosphorus were also measured, as behavior and balance of nitrogen and phosphorus are focused on. We observed following points by taking data of water quality; seasonal trend, changes occurred according to agricultural events like irrigation and fertilization. Nitrogen in ground water tends to high in June due to fertilizer. It is thought because farmers fertilize the filed before transplanting at the beginning of flooding season. Regarding to dissolved inorganic nitrogen, higher concentrations were observed in inflow water than in flooding water and outflow water. Though it needs discussion in loads as well as flow measurement, this suggests that nutrients are absorbed in paddy field and less nutrients are emitted after irrigation water passing through paddy field. Based on this research we are planning continuous investigation to assess environmental impact from paddy field.

  4. Dynamic nuclear polarization at high magnetic fields

    PubMed Central

    Maly, Thorsten; Debelouchina, Galia T.; Bajaj, Vikram S.; Hu, Kan-Nian; Joo, Chan-Gyu; Mak–Jurkauskas, Melody L.; Sirigiri, Jagadishwar R.; van der Wel, Patrick C. A.; Herzfeld, Judith; Temkin, Richard J.; Griffin, Robert G.

    2009-01-01

    Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (μw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (γe/γl), being ∼660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields. This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (≥5 T), the regime where contemporary NMR experiments are performed. After a brief historical survey, we present a review of the classical continuous wave (cw) DNP mechanisms—the Overhauser effect, the solid effect, the cross effect, and thermal mixing. A special section is devoted to the theory of coherent polarization transfer mechanisms, since they are potentially more efficient at high fields than classical polarization schemes. The implementation of DNP at high magnetic fields has required the development and improvement of new and existing instrumentation. Therefore, we also review some recent developments in μw and probe technology, followed by an overview of DNP applications in biological solids and liquids. Finally, we outline some possible areas for future developments. PMID:18266416

  5. High School Students' Representations and Understandings of Electric Fields

    ERIC Educational Resources Information Center

    Cao, Ying; Brizuela, Bárbara M.

    2016-01-01

    This study investigates the representations and understandings of electric fields expressed by Chinese high school students 15 to 16 years old who have not received high school level physics instruction. The physics education research literature has reported students' conceptions of electric fields post-instruction as indicated by students'…

  6. Investigation of trap properties in high-k/metal gate p-type metal-oxide-semiconductor field-effect-transistors with aluminum ion implantation using random telegraph noise analysis

    SciTech Connect

    Kao, Tsung-Hsien; Chang, Shoou-Jinn Fang, Yean-Kuen; Huang, Po-Chin; Wu, Chung-Yi; Wu, San-Lein

    2014-08-11

    In this study, the impact of aluminum ion implantation (Al I/I) on random telegraph noise (RTN) in high-k/metal gate (HK/MG) p-type metal-oxide-semiconductor field-effect-transistors (pMOSFETs) was investigated. The trap parameters of HK/MG pMOSFETs with Al I/I, such as trap energy level, capture time and emission time, activation energies for capture and emission, and trap location in the gate dielectric, were determined. The configuration coordinate diagram was also established. It was observed that the implanted Al could fill defects and form a thin Al{sub 2}O{sub 3} layer and thus increase the tunneling barrier height for holes. It was also observed that the trap position in the Al I/I samples was lower due to the Al I/I-induced dipole at the HfO{sub 2}/SiO{sub 2} interface.

  7. Recent biophysical studies in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Maret, Georg

    1990-06-01

    A brief overview of biophysical effects of steady magnetic fields is given. The need of high field strength is illustrated by several recent diamagnetic orientation experiments. They include rod-like viruses, purple membranes and chromosomes. Results of various studies on bees, quails, rats and pigeons exposed to fields above 7 T are also resumed.

  8. FIELD INVESTIGATION AND EVALUATION OF LAND TREATING TANNERY SLUDGES

    EPA Science Inventory

    Land treatment of wastewater sludges from tannery processes has been investigated during a five-year field plot study. The experimental design included eight field test plots receiving selected applications of three types of tannery sludges over a three-year period. The five-year...

  9. Investigations in Life Science, Junior High.

    ERIC Educational Resources Information Center

    Stephenson, Robert L.

    Developed for teachers of junior high school science classes, this unit presents ten investigations on plant growth, animal life, pond life, and general science interests. These investigations are designed to accompany any popular life science textbooks, may be used to supplement a year-long course in life science, are intended as a springboard…

  10. High-Field Phenomena of Qubits.

    PubMed

    van Tol, Johan; Morley, G W; Takahashi, S; McCamey, D R; Boehme, C; Zvanut, M E

    2009-12-01

    Electron and nuclear spins are very promising candidates to serve as quantum bits (qubits) for proposed quantum computers, as the spin degrees of freedom are relatively isolated from their surroundings and can be coherently manipulated, e.g., through pulsed electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR). For solid-state spin systems, impurities in crystals based on carbon and silicon in various forms have been suggested as qubits, and very long relaxation rates have been observed in such systems. We have investigated a variety of these systems at high magnetic fields in our multifrequency pulsed EPR/ENDOR (electron nuclear double resonance) spectrometer. A high magnetic field leads to large electron spin polarizations at helium temperatures, giving rise to various phenomena that are of interest with respect to quantum computing. For example, it allows the initialization of both the electron spin as well as hyperfine-coupled nuclear spins in a well-defined state by combining millimeter and radio-frequency radiation. It can increase the T(2) relaxation times by eliminating decoherence due to dipolar interaction and lead to new mechanisms for the coherent electrical readout of electron spins. We will show some examples of these and other effects in Si:P, SiC:N and nitrogen-related centers in diamond. PMID:19946596

  11. A Comparative Model of Field Investigations: Aligning School Science Inquiry with the Practices of Contemporary Science

    ERIC Educational Resources Information Center

    Windschitl, Mark; Dvornich, Karen; Ryken, Amy E.; Tudor, Margaret; Koehler, Gary

    2007-01-01

    Field investigations are not characterized by randomized and manipulated control group experiments; however, most school science and high-stakes tests recognize only this paradigm of investigation. Scientists in astronomy, genetics, field biology, oceanography, geology, and meteorology routinely select naturally occurring events and conditions and…

  12. The High School Players Field Hockey Journal.

    ERIC Educational Resources Information Center

    Schultz, Bobbie

    This student's journal aims at helping to develop a successful and highly motivated high school girls field hockey team. General information about the sport and student involvement is presented. Definitions of terms used in field hockey are given as well as general considerations about play, defensive and offensive strategies, and penalties.…

  13. Large Field, High Resolution Full-Field Optical Coherence Tomography

    PubMed Central

    Assayag, Osnath; Antoine, Martine; Sigal-Zafrani, Brigitte; Riben, Michael; Harms, Fabrice; Burcheri, Adriano; Grieve, Kate; Dalimier, Eugénie; Le Conte de Poly, Bertrand; Boccara, Claude

    2014-01-01

    We present a benchmark pilot study in which high-resolution Full-Field Optical Coherence Tomography (FF-OCT) was used to image human breast tissue and is evaluated to assess its ability to aid the pathologist’s management of intra-operative diagnoses. FF-OCT imaging safety was investigated and agreement between FF-OCT and routinely prepared histopathological images was evaluated. The compact setup used for this study provides 1 µm3 resolution and 200 µm imaging depth, and a 2.25 cm2 specimen is scanned in about 7 minutes. 75 breast specimens were imaged from 22 patients (21 women, 1 man) with a mean age of 58 (range: 25-83). Pathologists blind diagnosed normal/benign or malignant tissue based on FF-OCT images alone, diagnosis from histopathology followed for comparison. The contrast in the FF-OCT images is generated by intrinsic tissue scattering properties, meaning that no tissue staining or preparation is required. Major architectural features and tissue structures of benign breast tissue, including adipocytes, fibrous stroma, lobules and ducts were characterized. Subsequently, features resulting from pathological modification were characterized and a diagnosis decision tree was developed. Using FF-OCT images, two breast pathologists were able to distinguish normal/benign tissue from lesional with a sensitivity of 94% and 90%, and specificity of 75% and 79% respectively. PMID:24000981

  14. Liquid Droplet Dynamics in Gravity Compensating High Magnetic Field

    NASA Technical Reports Server (NTRS)

    Bojarevics, V.; Easter, S.; Pericleous, K.

    2012-01-01

    Numerical models are used to investigate behavior of liquid droplets suspended in high DC magnetic fields of various configurations providing microgravity-like conditions. Using a DC field it is possible to create conditions with laminar viscosity and heat transfer to measure viscosity, surface tension, electrical and thermal conductivities, and heat capacity of a liquid sample. The oscillations in a high DC magnetic field are quite different for an electrically conducting droplet, like liquid silicon or metal. The droplet behavior in a high magnetic field is the subject of investigation in this paper. At the high values of magnetic field some oscillation modes are damped quickly, while others are modified with a considerable shift of the oscillating droplet frequencies and the damping constants from the non-magnetic case.

  15. The Pioneer 11 high-field fluxgate magnetometer

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    The High Field Fluxgate Magnetometer Experiment flow aboard the Pioneer 11 spacecraft to investigate Jupiter's magnetic field is described. The instrument extends the spacecraft's upper limit measurement capability by more than an order of magnitude to 17.3 gauss with minimum power and volume requirements.

  16. Shemya AFB, Alaska 1992 IRP field investigation report

    SciTech Connect

    Not Available

    1993-02-01

    The US Air Force is currently investigating 22 sites on Shemya Air Force Base (AFB) to determine if past spill and disposal activities have caused environmental damage. These investigations are being carried out under the Air Force's Installation Restoration Program (IRP). As a part of the IRP program, field investigations were performed in 1992 to obtain the information needed to assess what future actions willneed to be carried out at each site. The island's drinking water supply was also investigated. Activities completed at 10 selected sites during the 1992 field investigation included surface sampling to determine the lateral extent of contamination, subsurface sampling to determine the vertical extent of contamination, and the installation of well points and monitoring wells to determine the direction of groundwater flow and if the groundwater has been affected by a site. In addition, geophysical surveys were performed at most sites to identify site boundaries and check for the presence of buried metal to be avoided during drilling activities.

  17. High-field magnetization of Dy2O3

    NASA Technical Reports Server (NTRS)

    Flood, D. J.

    1974-01-01

    The magnetization of powdered samples of Dy2O3 has been measured at temperatures between 1.45 deg and 4.2 K, in applied magnetic fields ranging to 7 Teslas. A linear dependence of magnetization on applied field is observable in high field region, the slope of which is independent of temperature over the range investigated. The extrapolated saturation magnetic moment is 2.77 + or - 0.08 Bohr magnetons per ion.

  18. High-field magnetization of Dy2O3

    NASA Technical Reports Server (NTRS)

    Flood, D. J.

    1974-01-01

    The magnetization of powdered samples of Dy2O3 has been measured at temperatures between 1.45 and 4.2 K, in applied magnetic fields ranging to 70 kilogauss. A linear dependence of magnetization on applied field is observable in the high-field region, the slope of which is independent of temperature over the range investigated. The extrapolated saturation magnetic moment is about 2.77 Bohr magnetons per ion.

  19. High Intensity Radiated Fields (HIRF) project plan

    NASA Astrophysics Data System (ADS)

    Glynn, Michael S.; Blair, Jerry T.; Hintze, M. Marx

    1991-09-01

    Addressed here is the Federal Aviation Administration's approach to High Intensity Radiated Fields (HIRF) affecting the aviation community. Near- and far-term tasks are described. Deliverables, program management, scheduling, and cost issues are discussed.

  20. SITE INVESTIGATIONS/FIELD INVESTIGATIONS OF SUPERFUND HAZARDOUS WASTE SITES: APRIL 1, 2003 - MAY 31, 2004

    EPA Science Inventory

    These projects require developing and implementing Work Plans which include the Project Operations Plan, Field Sampling and Analysis Plan, Quality Assurance Plan and the Health and Safety Plan. In general, these large complex investigations involve: collecting soil, sediment, sur...

  1. High magnetic field facilities in Latin America

    NASA Astrophysics Data System (ADS)

    Sato, R.; Grössinger, R.; Bertorello, H.; Broto, J. M.; Davies, H. A.; Estevez-Rams, E.; Gonzalez, J.; Matutes, J.; Sinnecker, J. P.; Sagredo, V.

    2006-11-01

    The EC supported a network (under the Framework 5 ALFA Programme) designated HIFIELD (Project number II0147FI) and entitled: "Measurement methods involving high magnetic fields for advanced and novel materials". As a result, high field facilities were initiated, constructed or extended at the following laboratories in Latin America: University Cordoba (Argentina), CES, Merida (Venezuela), CIMAV, Chihuahua (Mexico), University Federal de Rio de Janeiro (Brazil).

  2. Frustrated magnets in high magnetic fields-selected examples.

    PubMed

    Wosnitza, J; Zvyagin, S A; Zherlitsyn, S

    2016-07-01

    An indispensable parameter to study strongly correlated electron systems is the magnetic field. Application of high magnetic fields allows the investigation, modification and control of different states of matter. Specifically for magnetic materials experimental tools applied in such fields are essential for understanding their fundamental properties. Here, we focus on selected high-field studies of frustrated magnetic materials that have been shown to host a broad range of fascinating new and exotic phases. We will give brief insights into the influence of geometrical frustration on the critical behavior of triangular-lattice antiferromagnets, the accurate determination of exchange constants in the high-field saturated state by use of electron spin resonance measurements, and the coupling of magnetic degrees of freedom to the lattice evidenced by ultrasound experiments. The latter technique as well allowed new, partially metastable phases in strong magnetic fields to be revealed. PMID:27310818

  3. A High Field Magnet Design for A Future Hadron Collider

    SciTech Connect

    Gupta, R.; Chow, K.; Dietderich, D.; Gourlay, S.; Millos, G.; McInturff, A.; Scanlan, R.

    1998-09-01

    US high energy physics community is exploring the possibilities of building a Very Large Hadron Collider (VLHC) after the completion of LHC. This paper presents a high field magnet design option based on Nb{sub 3}Sn technology. A preliminary magnetic and mechanical design of a 14-16 T, 2-in-1 dipole based on the 'common coil design' approach is presented. The computer code ROXIE has been upgraded to perform the field quality optimization of magnets based on the racetrack coil geometry. A magnet R&D program to investigate the issues related to high field magnet designs is also outlined.

  4. Experiments to investigate particulate materials in reduced gravity fields

    NASA Technical Reports Server (NTRS)

    Bowden, M.; Eden, H. F.; Felsenthal, P.; Glaser, P. E.; Wechsler, A. E.

    1967-01-01

    Study investigates agglomeration and macroscopic behavior in reduced gravity fields of particles of known properties by measuring and correlating thermal and acoustical properties of particulate materials. Experiment evaluations provide a basis for a particle behavior theory and measure bulk properties of particulate materials in reduced gravity.

  5. Results of investigations at the Ahuachapan geothermal field, El Salvador

    SciTech Connect

    Dennis, B.; Goff, F.; Van Eeckhout, E.; Hanold, B.

    1990-04-01

    Well logging operations were performed in eight of the geothermal wells at Ahuachapan. High-temperature downhole instruments, including a temperature/rabbit, caliper, fluid velocity spinner/temperature/pressure (STP), and fluid sampler, were deployed in each well. The caliper tool was used primarily to determine if chemical deposits were present in well casings or liners and to investigate a suspected break in the casing in one well. STP logs were obtained from six of the eight wells at various flow rates ranging from 30 to 80 kg/s. A static STP log was also run with the wells shut-in to provide data to be used in the thermodynamic analysis of several production wells. The geochemical data obtained show a system configuration like that proposed by C. Laky and associates in 1989. Our data indicate recharge to the system from the volcanic highlands south of the field. Additionally, our data indicate encroachment of dilute fluids into deeper production zones because of overproduction. 17 refs., 50 figs., 10 tabs.

  6. Investigation of the light field of a semiconductor diode laser.

    PubMed

    Ankudinov, A V; Yanul, M L; Slipchenko, S O; Shelaev, A V; Dorozhkin, P S; Podoskin, A A; Tarasov, I S

    2014-10-20

    Scanning near-field optical microscopy was applied to study, with sub-wavelength spatial resolution, the near- and the far-field distributions of propagating modes from a high-power laser diode. Simple modeling was also performed and compared with experimental results. The simulated distributions were consistent with the experiment and permitted clarification of the configuration of the transverse modes of the laser. PMID:25401675

  7. Antenna development for high field plasma imaging

    SciTech Connect

    Kong, X.; Domier, C. W.; Luhmann, N. C. Jr.

    2010-10-15

    Electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) are two microwave nonperturbing plasma visualization techniques that employ millimeter-wave imaging arrays with lens-coupled planar antennas, yielding time-resolved images of temperature (via ECEI) and electron density (via MIR) fluctuations within high temperature magnetic fusion plasmas. A series of new planar antennas have been developed that extend this technology to frequencies as high as 220 GHz for use on high field plasma devices with toroidal fields in excess of 3 T. Antenna designs are presented together with theoretical calculations, simulations, and experimental measurements.

  8. The NASA High Intensity Radiated Fields Laboratory

    NASA Technical Reports Server (NTRS)

    Williams, Reuben A.

    1997-01-01

    High Intensity Radiated Fields (HIRF) are the result of a multitude of intentional and nonintentional electromagnetic sources that currently exists in the world. Many of today's digital systems are susceptible to electronic upset if subjected to certain electromagnetic environments (EME). Modern aerospace designers and manufacturers increasingly rely on sophisticated digital electronic systems to provide critical flight control in both military, commercial, and general aviation aircraft. In an effort to understand and emulate the undesired environment that high energy RF provides modern electronics, the Electromagnetics Research Branch (ERB) of the Flight Electronics and Technology Division (FETD) conducts research on RF and microwave measurement methods related to the understanding of HIRF. In the High Intensity Radiated Fields Laboratory, the effects of high energy radiating electromagnetic fields on avionics and electronic systems are tested and studied.

  9. Epidemiologic response to anthrax outbreaks: field investigations, 1950-2001.

    PubMed

    Bales, Michael E; Dannenberg, Andrew L; Brachman, Philip S; Kaufmann, Arnold F; Klatsky, Peter C; Ashford, David A

    2002-10-01

    We used unpublished reports, published manuscripts, and communication with investigators to identify and summarize 49 anthrax-related epidemiologic field investigations conducted by the Centers for Disease Control and Prevention from 1950 to August 2001. Of 41 investigations in which Bacillus anthracis caused human or animal disease, 24 were in agricultural settings, 11 in textile mills, and 6 in other settings. Among the other investigations, two focused on building decontamination, one was a response to bioterrorism threats, and five involved other causes. Knowledge gained in these investigations helped guide the public health response to the October 2001 intentional release of B. anthracis, especially by addressing the management of anthrax threats, prevention of occupational anthrax, use of antibiotic prophylaxis in exposed persons, use of vaccination, spread of B. anthracis spores in aerosols, clinical diagnostic and laboratory confirmation methods, techniques for environmental sampling of exposed surfaces, and methods for decontaminating buildings. PMID:12396934

  10. Molecular dynamics in high electric fields

    NASA Astrophysics Data System (ADS)

    Apostol, M.; Cune, L. C.

    2016-06-01

    Molecular rotation spectra, generated by the coupling of the molecular electric-dipole moments to an external time-dependent electric field, are discussed in a few particular conditions which can be of some experimental interest. First, the spherical-pendulum molecular model is reviewed, with the aim of introducing an approximate method which consists in the separation of the azimuthal and zenithal motions. Second, rotation spectra are considered in the presence of a static electric field. Two particular cases are analyzed, corresponding to strong and weak fields. In both cases the classical motion of the dipoles consists of rotations and vibrations about equilibrium positions; this motion may exhibit parametric resonances. For strong fields a large macroscopic electric polarization may appear. This situation may be relevant for polar matter (like pyroelectrics, ferroelectrics), or for heavy impurities embedded in a polar solid. The dipolar interaction is analyzed in polar condensed matter, where it is shown that new polarization modes appear for a spontaneous macroscopic electric polarization (these modes are tentatively called "dipolons"); one of the polarization modes is related to parametric resonances. The extension of these considerations to magnetic dipoles is briefly discussed. The treatment is extended to strong electric fields which oscillate with a high frequency, as those provided by high-power lasers. It is shown that the effect of such fields on molecular dynamics is governed by a much weaker, effective, renormalized, static electric field.

  11. Field and Laboratory Investigations of Organic Photochemistry on Urban Surfaces

    NASA Astrophysics Data System (ADS)

    Styler, S. A.; Baergen, A.; van Pinxteren, D.; Donaldson, D. J.; Herrmann, H.

    2014-12-01

    In polluted urban environments, windows and building surfaces rapidly become coated with a complex film of chemicals, which enhances the dry deposition of particles and the partitioning of semi-volatile organic species to the surface. Despite its high surface-to-volume ratio and direct exposure to sunlight, few studies have directly investigated the role that this "urban film" may play in promoting the photooxidative processing of semi-volatile organics contained within it. The present study represents a comprehensive field- and laboratory-based investigation of the film-phase photochemistry of polycyclic aromatic hydrocarbons (PAH), here used as proxies for light-absorbing semi-volatile organics present within the film. Urban film sampling was conducted using a custom-built three-stage sampler housing, which was deployed in a central, high-traffic area in Leipzig, Germany. The sampler itself employs small glass beads as surrogate window surfaces and is designed such that only its uppermost stage is exposed to sunlight. Each stage is subdivided into 16 compartments, which allows for the study of film formation and evolution. In the first phase of the study, the role of urban film as a photochemical sink for reactive organic species was determined by measuring total film PAH content and PAH abundance ratios as a function of atmospheric exposure time under both light and dark conditions. In the second, more general, phase of the study, the organic and inorganic composition of collected film samples was compared to that of co-located PM10 samples, and differences between the two sample types were used to gain insight into the relative importance of heterogeneous photochemical oxidation within the particle and film phases. In the third phase of the study, film samples grown under dark conditions were exposed to gas-phase ozone in an atmospheric-pressure flat-bed reactor, and the kinetics of ozone-induced PAH loss were studied under both dark and illuminated conditions

  12. High-field dipoles for future accelerators

    SciTech Connect

    Wipf, S.L.

    1984-09-01

    This report presents the concept for building superconducting accelerator dipoles with record high fields. Economic considerations favor the highest possible current density in the windings. Further discussion indicates that there is an optimal range of pinning strength for a superconducting material and that it is not likely for multifilamentary conductors to ever equal the potential performance of tape conductors. A dipole design with a tape-wound, inner high-field winding is suggested. Methods are detailed to avoid degradation caused by flux jumps and to overcome problems with the dipole ends. Concerns for force support structure and field precision are also addressed. An R and D program leading to a prototype 11-T dipole is outlined. Past and future importance of superconductivity to high-energy physics is evident from a short historical survey. Successful dipoles in the 10- to 20-T range will allow interesting options for upgrading present largest accelerators.

  13. Investigation on a field description of the chirped laser pulse

    NASA Astrophysics Data System (ADS)

    Chen, H. Y.; Huang, S. J.; Song, Q.; Wang, P. X.

    2016-02-01

    Starting from a first-order approximate field description function for laser pulses, the method currently used to approximate chirped laser pulse (CLP) substitutes frequency and wave vector related variables with spatiotemporally varying functions. We investigated the error involved by calculating the relative deviation from Maxwell equations. Errors for the electric and magnetic fields are analyzed separately, and behaviors related to parameter changes (that is, in laser width, pulse duration and chirp parameter) were studied. Results show that aberration associated with currently used field-description functions for CLP increases monotonically with chirp parameter, and the deviation introduced by chirping is proportional to the relative frequency span of the laser. Simulations based on these functions will lead to considerable error, especially for laser pulses with large chirping.

  14. Shemya AFB, Alaska 1992 IRP field investigation report

    SciTech Connect

    Not Available

    1993-02-01

    The US Air Force is currently investigating 22 sites on Shemya Air Force Base (AFB) to determine if past spill and disposal activities have caused environmental damage. These investigations are being carried out under the Air Force's Installation Restoration Program (IRP). Field investigations were performed in 1992 to obtain the information needed to assess what future actions will need to be carried out at each site. The island's drinking water supply was also investigated. Activities completed at 10 selected sites during the 1992 field investigation included surface sampling to determine the lateral extent of contamination, subsurface sampling to determine the vertical extent of contamination, and the installation of well points and monitoring wells to determine the direction of groundwater flow and if the groundwater has been affected by a site. In addition, geophysical surveys were performed at most sites to identify site boundaries and check for the presence of buried metal to be avoided during drilling activities. This report, appendix A, contains the analytical results.

  15. Community fear of nonionizing radiation: a field investigation

    SciTech Connect

    Daley, M.L.; Morton, W.E.; Chartier, V.; Zajac, H.; Benitez, H.

    1985-03-01

    Four children from the same school class developed cancer. Because of concern in the community, a field study designed to document levels of environmental, nonionizing radiation was undertaken. Two school sites were investigated, the one with the cluster of cases and the other without known cases of cancer. The measured values of nonionizing radiation at both sites were not different and were well below existing exposure standards.

  16. Regional Ecorisk Field investigation, upper Clark Fork River Basin

    SciTech Connect

    Pastorok, R.; LaTier, A.; Ginn, T.

    1995-12-31

    The Regional Ecorisk Field Investigation was conducted at the Clark Fork River Superfund Site (Montana) to evaluate the relationships between plant communities and tailings deposits in riparian habitats and to evaluate food-chain transfer of trace elements to selected wildlife species. Stations were selected to represent a range of vegetation biomass (or cover) values and apparent impact of trace elements, with some areas of lush vegetation, some areas of mostly unvegetated soil (e.g., < 30 percent plant cover), and a gradient in between. For the evaluation of risk to wildlife, bioaccumulation of metals was evaluated in native or naturalized plants, terrestrial invertebrates, and the deer mouse (Peromyscus maniculatus). Potential reproductive effects in the deer mouse were evaluated by direct measurements. For other wildlife species, bioaccumulation data were interpreted in the context of food web exposure models. Total biomass and species richness of riparian plant communities are related to tailings content of soil as indicated by pH and metals concentrations. Risk to populations of omnivorous small mammals such as the deer mouse was not significant. Relative abundance and reproductive condition of the deer mouse were normal, even in areas of high metals enrichment. Based on exposure models and site-specific tissue residue data for dietary species, risk to local populations of predators such as red fox and American kestrel that feed on deer mice and terrestrial invertebrates is not significant. Risk to herbivores related to metals bioaccumulation in plant tissues is not significant. Population level effects in deer and other large wildlife are not expected because of the large home ranges of such species and compensatory demographic factors.

  17. Design Studies for an Ultra High Field K80 Cyclotron

    NASA Astrophysics Data System (ADS)

    Schubert, Jeff; Blosser, Henry

    1996-05-01

    We are investigating the use of a wide-bore, 8 T magnet as a component of an ultra high field cyclotron. Such a machine would use the highest magnetic field of any cyclotron, to date. The K80 `Eight Tesla Cyclotron' would have roughly the same magnetic rigidity (Bρ) as the Oak Ridge Isochronous Cyclotron in a package of only one fourth the radius, with a corresponding reduction in cost. This cyclotron could accelerate particles with a charge state Q/A = 1/4 to a final energy of between 5 and 6 MeV/nucleon, the energy range currently being used to study superdeformed, high angular momentum nuclei that result from glancing collisions. Studies thus far have stressed achieving sufficient vertical focusing (ν_z) despite the high magnetic field level. The high field also reduces the space available for central region structures, which complicates early-turn focusing, orbit centering and the design of the spiral inflector.

  18. Space applications of superconductivity - High field magnets

    NASA Technical Reports Server (NTRS)

    Fickett, F. R.

    1979-01-01

    The paper discusses developments in superconducting magnets and their applications in space technology. Superconducting magnets are characterized by high fields (to 15T and higher) and high current densities combined with low mass and small size. The superconducting materials and coil design are being improved and new high-strength composites are being used for magnet structural components. Such problems as maintaining low cooling temperatures (near 4 K) for long periods of time and degradation of existing high-field superconductors at low strain levels can be remedied by research and engineering. Some of the proposed space applications of superconducting magnets include: cosmic ray analysis with magnetic spectrometers, energy storage and conversion, energy generation by magnetohydrodynamic and thermonuclear fusion techniques, and propulsion. Several operational superconducting magnet systems are detailed.

  19. Photoconductivity in ZnSe under high electric fields

    SciTech Connect

    Cho, P.S.; Ho, P.T.; Goldhar, J.; Lee, C.H. . Dept. of Electrical Engineering)

    1994-06-01

    High voltage photoconductive switches utilizing polycrystalline ZnSe were investigated. Experiments have been performed on polycrystalline ZnSe switches in a longitudinal geometry. Electrodes of perforated metal films, a transparent liquid electrolyte, plasma, and ultraviolet-light-generated carriers were used. High-bias fields of up to 100 kV/cm and current densities over 100 kA/cm[sup 2] can be applied to the polycrystalline ZnSe switches. Nonlinear effects were observed at high fields with near band edge illumination. Applications of these effects are discussed.

  20. Derivation of the high field semiconductor equations

    SciTech Connect

    Hagan, P.S. ); Cox, R.W. ); Wagner, B.A. . Dept. of Mathematics)

    1991-01-01

    Electron and hole densities evolve in x-z phase space according to Boltzmann equations. When the mean free path of the particles is short and electric force on the particles is weak, a well-known expansion can be used to solve the Boltzmann equation. This asymptotic solution shows that the spatial density of electrons and holes evolves according to diffusion-drift equations. As devices become smaller, electric fields become stronger, which renders the Basic Semiconductor Equations increasingly inaccurate. To remedy this problem, we use singular perturbation techniques to obtain a new asymptotic expansion for the Boltzmann equation. Like the Hilbert expansion, the new expansion requires the mean free path to be short compared to all macroscopic length scales. However, it does not require the electric forces to be weak. The new expansion shows that spatial densities obey diffusion-drift equations as before, but the diffusivity D and mobility {mu} turn out to be nonlinear functions of the electric field. In particular, our analysis determines the field-dependent mobilities {mu}(E) and diffusivities D(E) directly from the scattering operator. By carrying out this asymptotic expansion to higher order, we obtain the high frequency corrections to the drift velocity and diffusivity, and also the corrections due to gradients in the electric field. Remarkably, we find that Einsteins's relation is still satisfied, even with these corrections. The new diffusion-drift equations, together with Poissons' equation for the electric field, form the high-field semiconductor equations, which can be expected to be accurate regardless of the strength of the electric fields within the semiconductor. In addition, our analysis determines the entire momentum distribution of the particles, so we derive a very accurate first moment model for semi-conductors by substituting the asymptotically-correct distribution back into the Boltzmann equation and taking moments.

  1. Sultan - forced flow, high field test facility

    SciTech Connect

    Horvath, I.; Vecsey, G.; Weymuth, P.; Zellweger, J.

    1981-09-01

    Three European laboratories: CNEN (Frascati, I) ECN (Petten, NL) and SIN (Villigen, CH) decided to coordinate their development efforts and to install a common high field forced flow test facility at Villigen Switzerland. The test facility SULTAN (Supraleiter Testanlage) is presently under construction. As a first step, an 8T/1m bore solenoid with cryogenic periphery will be ready in 1981. The cryogenic system, data acquisition system and power supplies which are contributed by SIN are described. Experimental feasibilities, including cooling, and instrumentation are reviewed. Progress of components and facility construction is described. Planned extension of the background field up to 12T by insert coils is outlined. 5 refs.

  2. Investigating options for attenuating methane emission from Indian rice fields.

    PubMed

    Singh, S N; Verma, Amitosh; Tyagi, Larisha

    2003-08-01

    The development of methods and strategies to reduce the emission of methane from paddy fields is a central component of ongoing efforts to protect the Earth's atmosphere and to avert a possible climate change. It appears from this investigation that there can be more than one strategy to contain methane emission from paddy fields, which are thought to be a major source of methane emission in tropical Asia. Promising among the mitigating options may be water management, organic amendments, fertilizer application and selection of rice cultivars. It is always better to adopt multi-pronged strategies to contain CH4 efflux from rice wetlands. Use of fermented manures with low C/N ratio, application of sulfate-containing chemical fertilizers, selection of low CH4 emitting rice cultivars, and implementation of one or two short aeration periods before the heading stage can be effective options to minimize CH4 emission from paddy fields. Among these strategies, water management, which appears to be the best cost-effective and eco-friendly way for methane mitigation, is only possible when excess water is available for reflooding after short soil drying at the right timing and stage. However, in tropical Asia, rice fields are naturally flooded during the monsoonal rainy season and fully controlled drainage is often impossible. In such situation, water deficits during the vegetative and reproductive stage may drastically affect the rice yields. Thus, care must be taken to mitigate methane emission without affecting rice yields. PMID:12742397

  3. Structural investigations of Great Basin geothermal fields: Applications and implications

    SciTech Connect

    Faulds, James E; Hinz, Nicholas H.; Coolbaugh, Mark F

    2010-11-01

    Because fractures and faults are commonly the primary pathway for deeply circulating hydrothermal fluids, structural studies are critical to assessing geothermal systems and selecting drilling targets for geothermal wells. Important tools for structural analysis include detailed geologic mapping, kinematic analysis of faults, and estimations of stress orientations. Structural assessments are especially useful for evaluating geothermal fields in the Great Basin of the western USA, where regional extension and transtension combine with high heat flow to generate abundant geothermal activity in regions having little recent volcanic activity. The northwestern Great Basin is one of the most geothermally active areas in the USA. The prolific geothermal activity is probably due to enhanced dilation on N- to NNE-striking normal faults induced by a transfer of NW-directed dextral shear from the Walker Lane to NW-directed extension. Analysis of several geothermal fields suggests that most systems occupy discrete steps in normal fault zones or lie in belts of intersecting, overlapping, and/or terminating faults. Most fields are associated with steeply dipping faults and, in many cases, with Quaternary faults. The structural settings favoring geothermal activity are characterized by subvertical conduits of highly fractured rock along fault zones oriented approximately perpendicular to the WNW-trending least principal stress. Features indicative of these settings that may be helpful in guiding exploration for geothermal resources include major steps in normal faults, interbasinal highs, groups of relatively low discontinuous ridges, and lateral jogs or terminations of mountain ranges.

  4. Investigation of Magnetic Interference Induced via Gradient Field Coils for Ultra-Low-Field MRI Systems

    NASA Astrophysics Data System (ADS)

    Oyama, D.; Hatta, J.; Miyamoto, M.; Adachi, Y.; Higuchi, M.; Kawai, J.; Fujihira, J.; Tsuyuguchi, N.; Uehara, G.

    2014-05-01

    We are developing a compact ultra-low-field MRI system that is composed of a SQUID gradiometer and a coil set that generates magnetic fields for capturing MR images. The magnetic interference induced from a power amplifier potentially disturbs MRI measurements. We investigated the path of the interference by experimental measurements and calculation of the magnetic field generated by the coil set. We found that the magnetic field generated from a particular gradient coil affected the SQUID gradiometer and that the level of the interference was strongly dependent on the shape of the gradient coils. When the coils' shapes are designed, minimizing the noise introduced from the power amplifier is crucial, in addition to consideration of the homogeneities of the magnetic field.

  5. Interpretation and communication of the results of medical field investigations.

    PubMed

    Schulte, P A; Singal, M

    1989-07-01

    Since the controversy over cytogenetic test results at the Love Canal in New York State, there has been increasing concern about the communication of medical test results to participants in field studies. To identify the range of issues that arise and to present examples of practices that might be useful for consideration, we have drawn from 15 years of experience in interpreting and communicating the results of medical field investigations by the National Institute for Occupational Safety and Health. The investigations were qualitatively characterized according to study type and design, substances involved, language used in the notification of results, and the nature of the efforts to put results in perspective. Based on this evaluation, the following recommendations are made: (1) provide a comprehensible consent form, (2) interpret results for study participants, (3) use clear language, (4) be explicit about uncertainty of findings, (5) where appropriate, indicate the need for medical follow-up, (6) provide results promptly, (7) provide overall study results, (8) evaluate the impact of the notification, (9) train investigators in the practice of communicating results. PMID:2769455

  6. High-field EPR and ESEEM investigation of the nitrogen quadrupole interaction of nitroxide spin labels in disordered solids: toward differentiation between polarity and proticity matrix effects on protein function.

    PubMed

    Savitsky, A; Dubinskii, A A; Plato, M; Grishin, Y A; Zimmermann, H; Möbius, K

    2008-07-31

    The combination of high-field electron paramagnetic resonance (EPR) with site-directed spin labeling (SDSL) techniques employing nitroxide radicals has turned out to be particularly powerful in revealing subtle changes of the polarity and proticity profiles in proteins enbedded in membranes. This information can be obtained by orientation-selective high-field EPR resolving principal components of the nitroxide Zeeman (g) and hyperfine ( A) tensors of the spin labels attached to specific molecular sites. In contrast to the g- and A-tensors, the (14)N ( I = 1) quadrupole interaction tensor of the nitroxide spin label has not been exploited in EPR for probing effects of the microenvironment of functional protein sites. In this work it is shown that the W-band (95 GHz) high-field electron spin echo envelope modulation (ESEEM) method is well suited for determining with high accuracy the (14)N quadrupole tensor principal components of a nitroxide spin label in disordered frozen solution. By W-band ESEEM the quadrupole components of a five-ring pyrroline-type nitroxide radical in glassy ortho-terphenyl and glycerol solutions have been determined. This radical is the headgroup of the MTS spin label widely used in SDSL protein studies. By DFT calulations and W-band ESEEM experiments it is demonstrated that the Q(yy) value is especially sensitive to the proticity and polarity of the nitroxide environment in H-bonding and nonbonding situations. The quadrupole tensor is shown to be rather insensitive to structural variations of the nitroxide label itself. When using Q(yy) as a testing probe of the environment, its ruggedness toward temperature changes represents an important advantage over the g xx and A(zz) parameters which are usually employed for probing matrix effects on the spin labeled molecular site. Thus, beyond measurenments of g xx and A(zz) of spin labeled protein sites in disordered solids, W-band high-field ESEEM studies of (14)N quadrupole interactions open a new

  7. The Cluster magnetic field investigation: Scientific objectives and instrumentation

    NASA Technical Reports Server (NTRS)

    Balogh, A.; Cowley, S. W. H.; Dunlop, M. W.; Southwood, D. J.; Thomlinson, J. G.; Glassmeier, K. H.; Musmann, G.; Luehr, H.; Acuna, M. H.; Fairfield, D. H.

    1993-01-01

    The Cluster magnetic field investigation is presented. Cluster represents a qualitatively new type of space mission which will provide, for the first time, a three dimensional view of small scale plasma processes and structures in the different regions in and around the Earth's magnetosphere. Concepts of data analysis needed to interpret the four spacecraft magnetic field data in terms of magnetospheric processes and structures are outlined. The instrument itself, a vital component of the scientific payload, follows a long tradition of fluxgate magnetometers on space missions, yet represents an evolution in terms of built in functions and reliability. A detailed description of the instrument is given with emphasis on those aspects that are unique to the mission.

  8. Effective field investigation in arrays of polycrystalline ferromagnetic nanowires

    NASA Astrophysics Data System (ADS)

    Hernández, Eduardo Padrón; Rezende, S. M.; Azevedo, A.

    2008-04-01

    Nanowire arrays have been used as prototypes to investigate basic issues such as size effect, shape anisotropy, and dipolar interaction on the magnetic properties. Under ideal conditions, the nanowires are approximated as perfect long cylinders. Here, coherent rotation as the magnetization reversal mode cannot completely interpret the experimental data. The internal magnetic field value, in nanowire arrays, decreases due to the wire inhomogeneities and the dipolar interaction between the wires. Realistic models must account for the imperfections due to the fabrication process. Instead of it, in this work, a modified ellipsoid-chain array model is proposed to describe magnetization reversal in nanowire arrays. From the angular dependence of the ferromagnetic resonance field presented previously in the literature and from our proper results here, we present experimental confirmations to the model.

  9. The Pioneer XI high field fluxgate magnetometer

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    The high field fluxgate magnetometer experiment flown aboard the Pioneer XI spacecraft is described. This extremely simple instrument was used to extend the spacecraft's upper-limit measurement capability by approximately an order of magnitude (from 0.14 mT to 1.00 mT) with minimum power and volume requirements. This magnetometer was designed to complement the low-field measurements provided by a helium vector magnetometer and utilizes magnetic ring core sensors with biaxial orthogonal sense coils. The instrument is a single-range, triaxial-fluxgate magnetometer capable of measuring fields of up to 1 mT along each orthogonal axis, with a maximum resolution of 1 microT.

  10. High-resolution simulation of field emission

    SciTech Connect

    Herrmannsfeldt, W.B. ); Becker, R. ); Brodie, I.; Rosengreen, A.; Spindt, C.A. )

    1990-03-01

    High-resolution simulations of field emission electron sources have been made using the electron optics program EGN2. Electron emission distributions are made using the Fowler-Nordheim equation. Mesh resolution in the range of 1-5 {angstrom} is required to adequately model surface details that can result in emission currents in the range found experimentally. A typical problem starts with mechanical details with dimensions of about 1{mu}. To achieve high resolution a new boundary is defined by the tip, a nearby equipotential line, and a pair of field lines. The field lines (one of which is normally the axis of symmetry) define Neumann boundaries. This new boundary is then used by the boundary preprocessor POLYGON to create an enlarged version of the problem, typically by a factor of ten. This process can be repeated until adequate resolution is obtained to simulate surface details, such as microprotusion, that could sufficiently enhance the surface electric fields and cause field emission. When simulating experimental conditions under which emission of several microamperes per tip were observed, it was found that both a locally reduced work function and a surface protrusion were needed to duplicate the experimental results. If only a local region of reduced work function is used, the area involved and the extent of the reduction both need to be very large to reproduce the emission. If only a surface protrusion is used, it is possible to get the observed emission current with a reasonable protrusion of length a few times radius, but then the resulting beam spreads over a very large solid angle due to the strong local radial electric fields. 8 refs., 14 figs., 1 tab.

  11. Applications of high dielectric materials in high field magnetic resonance

    NASA Astrophysics Data System (ADS)

    Haines, Kristina Noel

    At high magnetic fields, radiation losses, wavelength effects, self-resonance, and the high resistance of components all contribute to losses in conventional RF MRI coil designs. The hypothesis tested here is that these problems can be combated by the use of high permittivity ceramic materials at high fields. High permittivity ceramic dielectric resonators create strong uniform magnetic fields in compact structures at high frequencies and can potentially solve some of the challenges of high field coil design. In this study NMR probes were constructed for operation at 600 MHz (14.1 Tesla) and 900 MHz (21.1 Tesla) using inductively fed CaTiO3 (relative permittivity of 156-166) cylindrical hollow bore dielectric resonators. The designs showed the electric field is largely confined to the dielectric itself, with near zero values in the hollow bore, which accommodates the sample. The 600 MHz probe has an unmatched Q value greater than 2000. Experimental and simulation mapping of the RF field show good agreement, with the ceramic resonator giving a pulse width approximately 25% less than a loop gap resonator of similar inner dimensions. High resolution images, with voxel dimensions less than 50 microm3, have been acquired from fixed zebrafish samples, showing excellent delineation of several fine structures. The 900 MHz probe has an unmatched Q value of 940 and shows Q performance five times better than Alderman-Grant and loop-gap resonators of similar dimensions. High resolution images were acquired of an excised mouse spinal cord (25 microm 3) and an excised rat soleus muscle (20 microm3). The spatial distribution of electromagnetic fields within the human body can be tailored using external dielectric materials. Here, a new material is introduced with high dielectric constant and low background MRI signal. The material is based upon metal titanates, which can be made into geometrically formable suspensions in de-ionized water. The suspension's material properties are

  12. High-purity silicon crystal growth investigations

    NASA Technical Reports Server (NTRS)

    Ciszek, T. F.; Schuyler, T.; Hurd, J. L.; Fearheiley, M.; Evans, C.; Elder, R.

    1986-01-01

    Information is given on evaporation and segregation contributions to impurity profiles of floating zone crystals (FZ); high-purity silicon float zoning (FZ); minority-carrier lifetime measurement of heavily doped silicon crystals; the effect of some crystal growth parameters on minority-carrier lifetime; and defect investigations by X-ray topography in graphical and tabular form. It was concluded that evaporation contributes substantially to impurity reduction when FZ or cold-crucible growth is conducted in a vacuum; boron and gallium may be more favorable dopants than indium or aluminum for obtaining high minority-carrier lifetimes; minority-carrier lifetimes greater than 100 microseconds are feasible at a 2 times 10 to the 17th power cm-3 doping level; minority-carrier lifetime decreases with increasing crystal cooling rate and also with the presence of dislocations; the method used to clean silicon feed rods affects lifetime; and microdefect densities in dislocation-free FZ crystals appear to be lower with Ga doping than with B doping.

  13. High Field Pulse Magnets with New Materials

    NASA Astrophysics Data System (ADS)

    Li, L.; Lesch, B.; Cochran, V. G.; Eyssa, Y.; Tozer, S.; Mielke, C. H.; Rickel, D.; van Sciver, S. W.; Schneider-Muntau, H. J.

    2004-11-01

    High performance pulse magnets using the combination of CuNb conductor and Zylon fiber composite reinforcement with bore sizes of 24, 15 and 10 mm have been designed, manufactured and tested to destruction. The magnets successfully reached the peak fields of 64, 70 and 77.8 T respectively with no destruction. Failures occurred near the end flanges at the layer. The magnet design, manufacturing and testing, and the mode of the failure are described and analyzed.

  14. SITE INVESTIGATIONS (SI) AND FIELD INVESTIGATIONS (FI) OF REGION 4 SUPERFUND HAZARDOUS WASTE SITES: OCTOBER 2006 – JULY 2007

    EPA Science Inventory

    Site Investigations (SIs) and Field Investigations (FIs) conducted by the Region 4 Science and Ecosystem Support Division (SESD) require developing and implementing work plans which include a Project Operations Plan, Field Sampling and Analysis Plan, Quality Assurance Project Pla...

  15. Shemya AFB, Alaska 1992 IRP field investigation report

    SciTech Connect

    Not Available

    1993-02-01

    The US Air Force is currently investigating 22 sites on Shemya Air Force Base (AFB) to determine if past spill and disposal activities have caused environmental damage. These investigations are being carried out under the Air Force's Installation Restoration Program (IRP). Field investigations were performed in 1992 to obtain the information needed to assess what future actions will need to be carried out at each site. The island's drinking water supply was also investigated. Activities completed at 10 selected sites included surface sampling to determine the lateral extent of contamination, subsurface sampling to determine the vertical extent of contamination, and the installation of well points and monitoring wells to determine the direction of groundwater flow and if the groundwater has been affected by a site. In addition, geophysical surveys were performed at most sites to identify site boundaries and check for the presence of buried metal, to be avoided during drilling activities. This report contains appendices E and F with information on the following: soil boring logs, and data validation of samples analyzed.

  16. Investigation of a supersonic cruise fighter model flow field

    NASA Technical Reports Server (NTRS)

    Reubush, D. E.; Bare, E. A.

    1985-01-01

    An investigation was conducted in the Langley 16-Foot Transonic Tunnel to survey the flow field around a model of a supersonic cruise fighter configuration. Local values of angle of attack, side flow, Mach number, and total pressure ratio were measured with a single multi-holed probe in three survey areas on a model previously used for nacelle/nozzle integration investigations. The investigation was conducted at Mach numbers of 0.6, 0.9, and 1.2, and at angles of attack from 0 deg to 10 deg. The purpose of the investigation was to provide a base of experimental data with which theoretically determined data can be compared. To that end the data are presented in tables as well as graphically, and a complete description of the model geometry is included as fuselage cross sections and wing span stations. Measured local angles of attack were generally greater than free stream angle of attack above the wing and generally smaller below. There were large spanwise local angle-of-attack and side flow gradients above the wing at the higher free stream angles of attack.

  17. Shemya AFB, Alaska 1992 IRP field investigation report

    SciTech Connect

    Not Available

    1993-02-01

    The US Air Force is currently investigating 22 sites on Shemya Air Force Base (AFB) to determine if past spill and disposal activities have caused environmental damage. These investigations are being carried out under the Air Force's Installation Restoration Program (IRP). Field investigations were performed in 1992 to obtain the information needed to assess what future actions will need to be carried out at each site. The island's drinking water supply was also investigated. Activities completed at 10 selected sites included surface sampling to determine the lateral extent of contamination, subsurface sampling to determine the vertical extent of contamination, and the installation of well points and monitoring wells to determine the direction of groundwater flow and if the groundwater has been affected by a site. Geophysical surveys were performed at most sites to identify site boundaries and check for the presence of buried metal to be avoided during drilling activities. This report, appendices B, C, and D contains information on the following: geophysical contour maps and profile plots; human health risk assessment; and ecological risk assessment.

  18. Investigation of the arcjet plume near field using electrostatic probes

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.

    1990-01-01

    The near field plum of a 1 kW class arcjet thruster was investigated using electrostatic probes of various geometries. The electron number densities and temperatures were determined in a simulated hydrazine plume at axial distances between 3 cm (1.2 in) and 15 cm (5.9 in) and radial distances extending to 10 cm (3.9 in) off centerline. Values of electron number densities obtained using cylindrical and spherical probes of different geometries agreed very well. The electron density on centerline followed a source flow approximation for axial distances as near as 3 cm (1.2 in) from the nozzle exit plane. The model agreed well with previously obtained data in the far field. The effects of propellant mass flow rate and input power level were also studied. Cylindrical probes were used to obtain ion streamlines by changing the probe orientation with respect to the flow. The effects of electrical configuration on the plasma characteristics of the plume were also investigated by using a segmented anode/nozzle thruster. The results showed that the electrical configuration in the nozzle affected the distribution of electrons in the plume.

  19. Investigation of the Arcjet near Field Plume Using Electrostatic Probes

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.

    1990-01-01

    The near field plume of a 1 kW class arcjet thruster was investigated using electrostatic probes of various geometries. The electron number densities and temperatures were determined in a simulated hydrazine plume at axial distances between 3 cm (1.2 in.) and 15 cm (5.9 in.) and radial distances extending to 10 cm (3.9 in.) off centerline. Values of electron number densities obtained using cylindrical and spherical probes of different geometries agreed very well. The electron density on centerline followed a source flow approximation for axial distances as near as 3 cm (1.2 in.) from the nozzle exit plane. The model agreed well with previously obtained data in the far field. The effects of propellant mass flow rate and input power level were also studied. Cylindrical probes were used to obtain ion streamlines by changing the probe orientation with respect to the flow. The effects of electrical configuration on the plasma characteristics of the plume were also investigated by using a segmented anode/nozzle thruster. The results showed that the electrical configuration in the nozzle affected the distribution of electrons in the plume.

  20. FINESSE: Field Investigations to Enable Solar System Science and Exploration

    NASA Technical Reports Server (NTRS)

    Heldmann, Jennifer; Lim, Darlene; Colaprete, Anthony

    2015-01-01

    The FINESSE (Field Investigations to Enable Solar System Science and Exploration) team is focused on a science and exploration field-based research program aimed at generating strategic knowledge in preparation for the human and robotic exploration of the Moon, near-Earth asteroids (NEAs) and Phobos and Deimos. We follow the philosophy that "science enables exploration and exploration enables science." 1) FINESSE Science: Understand the effects of volcanism and impacts as dominant planetary processes on the Moon, NEAs, and Phobos & Deimos. 2) FINESSE Exploration: Understand which exploration concepts of operations (ConOps) and capabilities enable and enhance scientific return. To accomplish these objectives, we are conducting an integrated research program focused on scientifically-driven field exploration at Craters of the Moon National Monument and Preserve in Idaho and at the West Clearwater Lake Impact Structure in northern Canada. Field deployments aimed at reconnaissance geology and data acquisition were conducted in 2014 at Craters of the Moon National Monument and Preserve. Targets for data acquisition included selected sites at Kings Bowl eruptive fissure, lava field and blowout crater, Inferno Chasm vent and outflow channel, North Crater lava flow and Highway lava flow. Field investigation included (1) differential GPS (dGPS) measurements of lava flows, channels (and ejecta block at Kings Bowl); (2) LiDAR imaging of lava flow margins, surfaces and other selected features; (3) digital photographic documentation; (4) sampling for geochemical and petrographic analysis; (5) UAV aerial imagery of Kings Bowl and Inferno Chasm features; and (6) geologic assessment of targets and potential new targets. Over the course of the 5-week field FINESSE campaign to the West Clearwater Impact Structure (WCIS) in 2014, the team focused on several WCIS research topics, including impactites, central uplift formation, the impact-generated hydrothermal system, multichronometer

  1. Investigation of back surface fields effect on bifacial solar cells

    NASA Astrophysics Data System (ADS)

    Sepeai, Suhaila; Sulaiman, M. Y.; Sopian, Kamaruzzaman; Zaidi, Saleem H.

    2012-11-01

    A bifacial solar cell, in contrast with a conventional monofacial solar cell, produces photo-generated current from both front and back sides. Bifacial solar cell is an attractive candidate for enhancing photovoltaic (PV) market competitiveness as well as supporting the current efforts to increase efficiency and lower material costs. This paper reports on the fabrication of bifacial solar cells using phosphorus-oxytrichloride (POCl3) emitter formation on p-type, nanotextured silicon (Si) wafer. Backside surface field was formed through Al-diffusion using conventional screen-printing process. Bifacial solar cells with a structure of n+pp+ with and without back surface field (BSF) were fabricated in which silicon nitride (SiN) anti reflection and passivation films were coated on both sides, followed by screen printing of Argentum (Ag) and Argentum/Aluminum (Ag/Al) on front and back contacts, respectively. Bifacial solar cells without BSF exhibited open circuit voltage (VOC) of 535 mV for front and 480 mV for back surface. With Al-alloyed BSF bifacial solar cells, the VOC improved to 580 mV for the front surface and 560 mV for the back surface. Simulation of bifacial solar cells using PC1D and AFORS software demonstrated good agreement with experimental results. Simulations showed that best bifacial solar cells are achieved through a combination of high lifetime wafer, low recombination back surface field, reduced contact resistance, and superior surface passivation.

  2. High-Gain High-Field Fusion Plasma

    NASA Astrophysics Data System (ADS)

    Li, Ge

    2015-10-01

    A Faraday wheel (FW)—an electric generator of constant electrical polarity that produces huge currents—could be implemented in an existing tokamak to study high-gain high-field (HGHF) fusion plasma, such as the Experimental Advanced Superconducting Tokamak (EAST). HGHF plasma can be realized in EAST by updating its pulsed-power system to compress plasma in two steps by induction fields; high gains of the Lawson trinity parameter and fusion power are both predicted by formulating the HGHF plasma. Both gain rates are faster than the decrease rate of the plasma volume. The formulation is checked by earlier ATC tests. Good agreement between theory and tests indicates that scaling to over 10 T at EAST may be possible by two-step compressions with a compression ratio of the minor radius of up to 3. These results point to a quick new path of fusion plasma study, i.e., simulating the Sun by EAST.

  3. High-Gain High-Field Fusion Plasma.

    PubMed

    Li, Ge

    2015-01-01

    A Faraday wheel (FW)-an electric generator of constant electrical polarity that produces huge currents-could be implemented in an existing tokamak to study high-gain high-field (HGHF) fusion plasma, such as the Experimental Advanced Superconducting Tokamak (EAST). HGHF plasma can be realized in EAST by updating its pulsed-power system to compress plasma in two steps by induction fields; high gains of the Lawson trinity parameter and fusion power are both predicted by formulating the HGHF plasma. Both gain rates are faster than the decrease rate of the plasma volume. The formulation is checked by earlier ATC tests. Good agreement between theory and tests indicates that scaling to over 10 T at EAST may be possible by two-step compressions with a compression ratio of the minor radius of up to 3. These results point to a quick new path of fusion plasma study, i.e., simulating the Sun by EAST. PMID:26507314

  4. Investigations on the Incompletely Developed Plane Diagonal-Tension Field

    NASA Technical Reports Server (NTRS)

    Kuhn, Paul

    1940-01-01

    This report presents the results of an investigation on the incompletely developed diagonal-tension field. Actual diagonal-tension beams work in an intermediate stage between pure shear and pure diagonal tension; the theory developed by wagner for diagonal tension is not directly applicable. The first part of the paper reviews the most essential items of the theory of pure diagonal tension as well as previous attempts to formulate a theory of incomplete diagonal tension. The second part of the paper describes strain measurement made by the N. A. C. A. to obtain the necessary coefficients for the proposed theory. The third part of the paper discusses the stress analysis of diagonal-tension beams by means of the proposed theory.

  5. Investigation of Polarization Phase Difference Related to Forest Fields Characterizations

    NASA Astrophysics Data System (ADS)

    Majidi, M.; Maghsoudi, Y.

    2013-09-01

    The information content of Synthetic Aperture Radar (SAR) data significantly included in the radiometric polarization channels, hence polarimetric SAR data should be analyzed in relation with target structure. The importance of the phase difference between two co-polarized scattered signals due to the possible association between the biophysical parameters and the measured Polarization Phase Difference (PPD) statistics of the backscattered signal recorded components has been recognized in geophysical remote sensing. This paper examines two Radarsat-2 images statistics of the phase difference to describe the feasibility of relationship with the physical properties of scattering targets and tries to understand relevance of PPD statistics with various types of forest fields. As well as variation of incidence angle due to affecting on PPD statistics is investigated. The experimental forest pieces that are used in this research are characterized white pine (Pinus strobus L.), red pine (Pinus resinosa Ait.), jack pine (Pinus banksiana Lamb.), white spruce (Picea glauca (Moench Voss), black spruce (Picea mariana (Mill) B.S.P.), poplar (Populus L.), red oak (Quercus rubra L.) , aspen and ground vegetation. The experimental results show that despite of biophysical parameters have a wide diversity, PPD statistics are almost the same. Forest fields distributions as distributed targets have close to zero means regardless of the incidence angle. Also, The PPD distribution are function of both target and sensor parameters, but for more appropriate examination related to PPD statistics the observations should made in the leaf-off season or in bands with lower frequencies.

  6. Continuous field investigation assessing nitrogen and phosphorus emission from irrigated paddy field

    NASA Astrophysics Data System (ADS)

    Kogure, Kanami; Aichi, Masaatsu; Zessner, Matthias

    2016-04-01

    In order to maintain good river environment, it is very important to understand and to control nutrient behavior such as Nitrogen and Phosphorus. Other than urban and industrial waste water, nutrient emission from agricultural activity is dominant pollution source into the river system. Rice is one of the staple products of Asia and paddy field occupies large areas in Asian countries. Rice is also widely cultivated in Japan. Paddy field occupies large areas in Japanese river basin areas. While paddy field can deteriorate river water quality by discharging fertilizer, it is also suggested that paddy field has water purification function. Regarding to nutrient emission from paddy field, existing monitored data are insufficient so as to discuss quantitatively seasonal change of material behavior including flooding season and dry season and to evaluate year round comprehensive impact from paddy field to the river system. These are not sufficient data for discussion of material flow and emission impact quantitatively as well as qualitatively. We have carried out field investigation in paddy fields in middle reach of the Tone River Basin. The aim of the survey is understanding of water and nutrient balance in paddy field. In order to understand emission impact from paddy field to river system, all input and output flow are measured to calculate nutrient balance in paddy field. Therefore we observed quantity of water flow into/from paddy field, water quality change of inflow and outflow during flooding season. We set focus on a monitoring paddy field IM, and monitored continuously water and nutrient behavior. By measuring water quality and flow rate of inflow, outflow, infiltrating water, ground water and depth of flooding water, we tried to quantitatively understand N and P cycle around paddy field including seasonal tendency, change accompanying with rainy events and occurred according to agricultural events like fertilization. At the beginning of flooding season, we

  7. Empirical models of high latitude electric fields

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1976-01-01

    Model cross sections of the high latitude dawn-dusk electric field based on OGO-6 data are presented for the signature profiles, most frequently encountered for both + and -Y orientations of the interplanetary magnetic field. Line integrals give a total potential of 76 keV in each case. To illustrate extremes, examples of model cross-sections with total potentials of 23 keV and 140 keV are also given. Model convection patterns are also presented utilizing OGO-6 data on boundary locations at other magnetic local times. When this information is combined with characteristic field geometries in the region of the Harang discontinuity, and is supplemented by data from Ba+ cloud motions in the polar cap, it becomes possible to construct realistic convection patterns on the nightside which deviate from the usual sun-aligned patterns. The observational models presented are of limited applicability as a consequence of the variability of observed distributions. These limitations are emphasized with particular attention given to several types of recurrent deviations which have not previously been discussed.

  8. Structural alloys for high field superconducting magnets

    SciTech Connect

    Morris, J.W. Jr.

    1985-08-01

    Research toward structural alloys for use in high field superconducting magnets is international in scope, and has three principal objectives: the selection or development of suitable structural alloys for the magnet support structure, the identification of mechanical phenomena and failure modes that may influence service behavior, and the design of suitable testing procedures to provide engineering design data. This paper reviews recent progress toward the first two of these objectives. The structural alloy needs depend on the magnet design and superconductor type and differ between magnets that use monolithic and those that employ force-cooled or ICCS conductors. In the former case the central requirement is for high strength, high toughness, weldable alloys that are used in thick sections for the magnet case. In the latter case the need is for high strength, high toughness alloys that are used in thin welded sections for the conductor conduit. There is productive current research on both alloy types. The service behavior of these alloys is influenced by mechanical phenomena that are peculiar to the magnet environment, including cryogenic fatigue, magnetic effects, and cryogenic creep. The design of appropriate mechanical tests is complicated by the need for testing at 4/sup 0/K and by rate effects associated with adiabatic heating during the tests. 46 refs.

  9. Distinguishing among Declarative, Descriptive and Causal Questions to Guide Field Investigations and Student Assessment

    ERIC Educational Resources Information Center

    Odom, Arthur Louis; Bell, Clare V.

    2011-01-01

    Teachers as well as students often have difficulty formulating good research questions because not all questions lend themselves to scientific investigation. The following is a guide for high-school and college life-science teachers to help students define question types central to biological field studies. The mayfly nymph was selected as the…

  10. Remedial investigation report for J-Field, Aberdeen Proving Ground, Maryland. Volume 1: Remedial investigation results

    SciTech Connect

    Yuen, C. R.; Martino, L. E.; Biang, R. P.; Chang, Y. S.; Dolak, D.; Van Lonkhuyzen, R. A.; Patton, T. L.; Prasad, S.; Quinn, J.; Rosenblatt, D. H.; Vercellone, J.; Wang, Y. Y.

    2000-03-14

    This report presents the results of the remedial investigation (RI) conducted at J-Field in the Edgewood Area of Aberdeen Proving Ground (APG), a U.S. Army installation located in Harford County, Maryland. Since 1917, activities in the Edgewood Area have included the development, manufacture, and testing of chemical agents and munitions and the subsequent destruction of these materials at J-Field by open burning and open detonation. These activities have raised concerns about environmental contamination at J-Field. This RI was conducted by the Environmental Conservation and Restoration Division, Directorate of Safety, Health and Environmental Division of APG, pursuant to requirements outlined under the Comprehensive Environmental Response, Compensation, and Liability Act, as amended (CERCLA). The RI was accomplished according to the procedures developed by the U.S. Environmental Protection Agency (EPA 1988). The RI provides a comprehensive evaluation of the site conditions, nature of contaminants present, extent of contamination, potential release mechanisms and migration pathways, affected populations, and risks to human health and the environment. This information will be used as the basis for the design and implementation of remedial actions to be performed during the remedial action phase, which will follow the feasibility study (FS) for J-Field.

  11. A field investigation and numerical simulation of coastal fog

    NASA Technical Reports Server (NTRS)

    Mack, E. J.; Eadie, W. J.; Rogers, C. W.; Kocmond, W. C.; Pilie, R. J.

    1973-01-01

    A field investigation of the microphysical and micrometeorological features of fogs occurring near Los Angeles and Vandenberg, California was conducted. Observations of wind speed and direction, temperature, dew point, vertical wind velocity, dew deposition, drop-size distribution, liquid water content, and haze and cloud nucleus concentration were obtained. These observations were initiated in late evening prior to fog formation and continued until the time of dissipation in both advection and radiation fogs. Data were also acquired in one valley fog and several dense haze situations. The behavior of these parameters prior to and during fog are discussed in detail. A two-dimensional numerical model was developed to investigate the formation and dissipation of advection fogs under the influence of horizontal variations in surface temperature. The model predicts the evolution of potential temperature, water vapor content, and liquid water content in a vertical plane as determined by vertical turbulent transfer and horizontal advection. Results are discussed from preliminary numerical experiments on the formation of warm-air advection fog and dissipation by natural and artificial heating from the surface.

  12. Effect of magnetic field inhomogeneity on ion cyclotron motion coherence at high magnetic field.

    PubMed

    Vladimirov, Gleb; Kostyukevich, Yury; Hendrickson, Christopher L; Blakney, Greg T; Nikolaev, Eugene

    2015-01-01

    A three-dimensional code based on the particle-in-cell algorithm modified to account for the inhomogeneity of the magnetic field was applied to determine the effect of Z(1), Z(2), Z(3), Z(4), X, Y, ZX, ZY, XZ(2) YZ(2), XY and X(2)-Y(2) components of an orthogonal magnetic field expansion on ion motion during detection in an FT-ICR cell. Simulations were performed for magnetic field strengths of 4.7, 7, 14.5 and 21 Tesla, including experimentally determined magnetic field spatial distributions for existing 4.7 T and 14.5 T magnets. The effect of magnetic field inhomogeneity on ion cloud stabilization ("ion condensation") at high numbers of ions was investigated by direct simulations of individual ion trajectories. Z(1), Z(2), Z(3) and Z(4) components have the largest effect (especially Z(1)) on ion cloud stability. Higher magnetic field strength and lower m/z demand higher relative magnetic field homogeneity to maintain cloud coherence for a fixed time period. The dependence of mass resolving power upper limit on Z(1) inhomogeneity is evaluated for different magnetic fields and m/z. The results serve to set the homogeneity requirements for various orthogonal magnetic field components (shims) for future FT-ICR magnet design. PMID:26307725

  13. High-field thermal transport properties of REBCO coated conductors

    NASA Astrophysics Data System (ADS)

    Bonura, Marco; Senatore, Carmine

    2015-02-01

    The use of REBCO coated conductors (CCs) is envisaged for many applications, extending from power cables to high-field magnets. Whatever the case, thermal properties of REBCO tapes play a key role for the stability of superconducting devices. In this work, we present the first study on the longitudinal thermal conductivity (κ) of REBCO CCs in magnetic fields up to 19 T applied both parallel and perpendicularly to the thermal-current direction. Copper-stabilized tapes from six industrial manufacturers have been investigated. We show that zero-field κ of CCs can be calculated with an accuracy of +/- 15% from the residual resistivity ratio of the stabilizer and the Cu/non-Cu ratio. Measurements performed at high fields have allowed us to evaluate the consistency of the procedures generally used for estimating in-field κ in the framework of the Wiedemann-Franz law from an electrical characterization of the materials. In-field data are intended to provide primary ingredients for the thermal stability analysis of high-temperature superconductor-based magnets.

  14. Physical processes at high field strengths

    SciTech Connect

    Rhodes, C.K.

    1986-01-01

    Measurements of the radiation produced by the high field interaction with the rare gases have revealed the presence of both copious harmonic production and fluorescence. The highest harmonic observed was the seventeenth (14.6 rm) in Ne, the shortest wavelength ever produced by that means. Strong fluorescence was seen in Ar, Kr, and Xe with the shortest wavelengths observed being below 10 nm. Furthermore, radiation from inner-shell excited configurations in Xe, specifically the 4d/sup 9/5s5p ..-->.. 4d/sup 10/5s manifold at approx. 17.7 nm, was detected. The behaviors of the rare gases with respect to multiquantum ionization, harmonic production, and fluorescence were found to be correlated so that the materials fell into two groups, He and Ne in one and Ar, Kr, and Xe in the other. These experimental findings, in alliance with other studies on inner-shell decay processes, give evidence for a role of atomic correlations in a direct nonlinear process of inner-shell excitation. It is expected that an understanding of these high-field processes will enable the generation of stimulated emission in the x-ray range. 59 refs., 6 figs., 5 tabs.

  15. A high performance field-reversed configuration

    SciTech Connect

    Binderbauer, M. W.; Tajima, T.; Steinhauer, L. C.; Garate, E.; Tuszewski, M.; Smirnov, A.; Gota, H.; Barnes, D.; Deng, B. H.; Thompson, M. C.; Trask, E.; Yang, X.; Putvinski, S.; Rostoker, N.; Andow, R.; Aefsky, S.; Bolte, N.; Bui, D. Q.; Ceccherini, F.; Clary, R.; and others

    2015-05-15

    Conventional field-reversed configurations (FRCs), high-beta, prolate compact toroids embedded in poloidal magnetic fields, face notable stability and confinement concerns. These can be ameliorated by various control techniques, such as introducing a significant fast ion population. Indeed, adding neutral beam injection into the FRC over the past half-decade has contributed to striking improvements in confinement and stability. Further, the addition of electrically biased plasma guns at the ends, magnetic end plugs, and advanced surface conditioning led to dramatic reductions in turbulence-driven losses and greatly improved stability. Together, these enabled the build-up of a well-confined and dominant fast-ion population. Under such conditions, highly reproducible, macroscopically stable hot FRCs (with total plasma temperature of ∼1 keV) with record lifetimes were achieved. These accomplishments point to the prospect of advanced, beam-driven FRCs as an intriguing path toward fusion reactors. This paper reviews key results and presents context for further interpretation.

  16. A high performance field-reversed configurationa)

    NASA Astrophysics Data System (ADS)

    Binderbauer, M. W.; Tajima, T.; Steinhauer, L. C.; Garate, E.; Tuszewski, M.; Schmitz, L.; Guo, H. Y.; Smirnov, A.; Gota, H.; Barnes, D.; Deng, B. H.; Thompson, M. C.; Trask, E.; Yang, X.; Putvinski, S.; Rostoker, N.; Andow, R.; Aefsky, S.; Bolte, N.; Bui, D. Q.; Ceccherini, F.; Clary, R.; Cheung, A. H.; Conroy, K. D.; Dettrick, S. A.; Douglass, J. D.; Feng, P.; Galeotti, L.; Giammanco, F.; Granstedt, E.; Gupta, D.; Gupta, S.; Ivanov, A. A.; Kinley, J. S.; Knapp, K.; Korepanov, S.; Hollins, M.; Magee, R.; Mendoza, R.; Mok, Y.; Necas, A.; Primavera, S.; Onofri, M.; Osin, D.; Rath, N.; Roche, T.; Romero, J.; Schroeder, J. H.; Sevier, L.; Sibley, A.; Song, Y.; Van Drie, A. D.; Walters, J. K.; Waggoner, W.; Yushmanov, P.; Zhai, K.

    2015-05-01

    Conventional field-reversed configurations (FRCs), high-beta, prolate compact toroids embedded in poloidal magnetic fields, face notable stability and confinement concerns. These can be ameliorated by various control techniques, such as introducing a significant fast ion population. Indeed, adding neutral beam injection into the FRC over the past half-decade has contributed to striking improvements in confinement and stability. Further, the addition of electrically biased plasma guns at the ends, magnetic end plugs, and advanced surface conditioning led to dramatic reductions in turbulence-driven losses and greatly improved stability. Together, these enabled the build-up of a well-confined and dominant fast-ion population. Under such conditions, highly reproducible, macroscopically stable hot FRCs (with total plasma temperature of ˜1 keV) with record lifetimes were achieved. These accomplishments point to the prospect of advanced, beam-driven FRCs as an intriguing path toward fusion reactors. This paper reviews key results and presents context for further interpretation.

  17. High-field Magnet Development toward the High Luminosity LHC

    SciTech Connect

    Apollinari, Giorgio

    2014-07-01

    The upcoming Luminosity upgrade of the LHC (HL-LHC) will rely on the use of Accelerator Quality Nb3Sn Magnets which have been the focus of an intense R&D effort in the last decade. This contribution will describe the R&D and results of Nb3Sn Accelerator Quality High Field Magnets development efforts, with emphasis on the activities considered for the HL-LHC upgrades.

  18. Stepped Impedance Resonators for High Field Magnetic Resonance Imaging

    PubMed Central

    Akgun, Can E.; DelaBarre, Lance; Yoo, Hyoungsuk; Sohn, Sung-Min; Snyder, Carl J.; Adriany, Gregor; Ugurbil, Kamil; Gopinath, Anand; Vaughan, J. Thomas

    2014-01-01

    Multi-element volume radio-frequency (RF) coils are an integral aspect of the growing field of high field magnetic resonance imaging (MRI). In these systems, a popular volume coil of choice has become the transverse electromagnetic (TEM) multi-element transceiver coil consisting of microstrip resonators. In this paper, to further advance this design approach, a new microstrip resonator strategy in which the transmission line is segmented into alternating impedance sections referred to as stepped impedance resonators (SIRs) is investigated. Single element simulation results in free space and in a phantom at 7 tesla (298 MHz) demonstrate the rationale and feasibility of the SIR design strategy. Simulation and image results at 7 tesla in a phantom and human head illustrate the improvements in transmit magnetic field, as well as, RF efficiency (transmit magnetic field versus SAR) when two different SIR designs are incorporated in 8-element volume coil configurations and compared to a volume coil consisting of microstrip elements. PMID:23508243

  19. High-field transport in two-dimensional graphene

    NASA Astrophysics Data System (ADS)

    Fang, Tian; Konar, Aniruddha; Xing, Huili; Jena, Debdeep

    2011-09-01

    Transport of carriers in two-dimensional graphene at high electric fields is investigated by combining semianalytical and Monte Carlo methods. A semianalytical high-field transport model based on the high rate of optical phonon emission provides useful estimates of the saturation currents in graphene. For developing a more accurate picture, the nonequilibrium (hot) phonon effect and the role of electron-electron scattering were studied using Monte Carlo simulations. Monte Carlo simulations indicate that the hot phonon effect plays a dominant role in current saturation, and electron-electron scattering strongly thermalizes the hot carrier population in graphene. We also find that electron-electron scattering removes negative differential resistance in graphene. Transient phenomenon such as velocity overshoot can be used to speed up graphene-based high-speed electronic devices by shrinking the channel length below 80 nm if electrostatic control can be exercised in the absence of a band gap.

  20. Guided resonances on lithium niobate for extremely small electric field detection investigated by accurate sensitivity analysis.

    PubMed

    Qiu, Wentao; Ndao, Abdoulaye; Lu, Huihui; Bernal, Maria-Pilar; Baida, Fadi Issam

    2016-09-01

    We present a theoretical study of guided resonances (GR) on a thin film lithium niobate rectangular lattice photonic crystal by band diagram calculations and 3D Finite Difference Time Domain (FDTD) transmission investigations which cover a broad range of parameters. A photonic crystal with an active zone as small as 13μm×13μm×0.7μm can be easily designed to obtain a resonance Q value in the order of 1000. These resonances are then employed in electric field (E-field) sensing applications exploiting the electro optic (EO) effect of lithium niobate. A local field factor that is calculated locally for each FDTD cell is proposed to accurately estimate the sensitivity of GR based E-field sensor. The local field factor allows well agreement between simulations and reported experimental data therefore providing a valuable method in optimizing the GR structure to obtain high sensitivities. When these resonances are associated with sub-picometer optical spectrum analyzer and high field enhancement antenna design, an E-field probe with a sensitivity of 50 μV/m could be achieved. The results of our simulations could be also exploited in other EO based applications such as EEG (Electroencephalography) or ECG (Electrocardiography) probe and E-field frequency detector with an 'invisible' probe to the field being detected etc. PMID:27607627

  1. High field magnetic resonance imaging of rodents in cardiovascular research.

    PubMed

    Vanhoutte, Laetitia; Gerber, Bernhard L; Gallez, Bernard; Po, Chrystelle; Magat, Julie; Jean-Luc, Balligand; Feron, Olivier; Moniotte, Stéphane

    2016-07-01

    Transgenic and gene knockout rodent models are primordial to study pathophysiological processes in cardiovascular research. Over time, cardiac MRI has become a gold standard for in vivo evaluation of such models. Technical advances have led to the development of magnets with increasingly high field strength, allowing specific investigation of cardiac anatomy, global and regional function, viability, perfusion or vascular parameters. The aim of this report is to provide a review of the various sequences and techniques available to image mice on 7-11.7 T magnets and relevant to the clinical setting in humans. Specific technical aspects due to the rise of the magnetic field are also discussed. PMID:27287250

  2. Numerical Investigation of Near-Field Plasma Flows in Magnetic Nozzles

    NASA Technical Reports Server (NTRS)

    Sankaran, Kamesh; Polzin, Kurt A.

    2009-01-01

    The development and application of a multidimensional numerical simulation code for investigating near-field plasma processes in magnetic nozzles are presented. The code calculates the time-dependent evolution of all three spatial components of both the magnetic field and velocity in a plasma flow, and includes physical models of relevant transport phenomena. It has been applied to an investigation of the behavior of plasma flows found in high-power thrusters, employing a realistic magnetic nozzle configuration. Simulation of a channel-flow case where the flow was super-Alfvenic has demonstrated that such a flow produces adequate back-emf to significantly alter the shape of the total magnetic field, preventing the flow from curving back to the magnetic field coil in the near-field region. Results from this simulation can be insightful in predicting far-field behavior and can be used as a set of self-consistent boundary conditions for far-field simulations. Future investigations will focus on cases where the inlet flow is sub-Alfvenic and where the flow is allowed to freely expand in the radial direction once it is downstream of the coil.

  3. Field site investigation: Effect of mine seismicity on groundwater hydrology

    SciTech Connect

    Ofoegbu, G.I.; Hsiung, S.; Chowdhury, A.H.; Philip, J.

    1995-04-01

    The results of a field investigation on the groundwater-hydrologic effect of mining-induced earthquakes are presented in this report. The investigation was conducted at the Lucky Friday Mine, a silver-lead-zinc mine in the Coeur d`Alene Mining District of Idaho. The groundwater pressure in sections of three fracture zones beneath the water table was monitored over a 24-mo period. The fracture zones were accessed through a 360-m-long inclined borehole, drilled from the 5,700 level station of the mine. The magnitude, source location, and associated ground motions of mining-induced seismic events were also monitored during the same period, using an existing seismic instrumentation network for the mine, augmented with additional instruments installed specifically for the project by the center for Nuclear Waste Regulatory Analyses (CNWRA). More than 50 seismic events of Richter magnitude 1.0 or larger occurred during the monitoring period. Several of these events caused the groundwater pressure to increase, whereas a few caused it to decrease. Generally, the groundwater pressure increased as the magnitude of seismic event increased; for an event of a given magnitude, the groundwater pressure increased by a smaller amount as the distance of the observation point from the source of the event increased. The data was examined using regression analysis. Based on these results, it is suggested that the effect of earthquakes on groundwater flow may be better understood through mechanistic modeling. The mechanical processes and material behavior that would need to be incorporated in such a model are examined. They include a description of the effect of stress change on the permeability and water storage capacity of a fracture rock mass; transient fluid flow; and the generation and transmission of seismic waves through the rock mass.

  4. Investigation of turbulence in reversed field pinch plasma by using microwave imaging reflectometry

    SciTech Connect

    Shi, Z. B.; Nagayama, Y.; Hamada, Y.; Yamaguchi, S.; Hirano, Y.; Kiyama, S.; Koguchi, H.; Sakakita, H.; Michael, C. A.; Yambe, K.

    2011-10-15

    Turbulence in the reversed field pinch (RFP) plasma has been investigated by using the microwave imaging reflectometry in the toroidal pinch experiment RX (TPE-RX). In conventional RFP plasma, the fluctuations are dominated by the intermittent blob-like structures. These structures are accompanied with the generation of magnetic field, the strong turbulence, and high nonlinear coupling among the high and low k modes. The pulsed poloidal current drive operation, which improves the plasma confinement significantly, suppresses the dynamo, the turbulence, and the blob-like structures.

  5. Inviscid fluid in high frequency excitation field

    NASA Technical Reports Server (NTRS)

    Zak, M.

    1984-01-01

    The influence of high frequency excitations (HFE) on a fluid is investigated. The response to these excitations is decomposed in two parts: 'slow' motion, which practically remains unchanged during the vanishingly small period tau, and 'fast' motion whose value during this period is negligible in terms of displacements, but is essential in terms of the kinetic energy. After such a decomposition the 'slow' and 'fast' motions become nonlinearly coupled by the corresponding governing equations. This coupling leads to an 'effective' potential energy which imparts some 'elastic' properties to the fluid and stabilizes laminar flows.

  6. First results of the MAVEN magnetic field investigation

    NASA Astrophysics Data System (ADS)

    Connerney, J. E. P.; Espley, J. R.; DiBraccio, G. A.; Gruesbeck, J. R.; Oliversen, R. J.; Mitchell, D. L.; Halekas, J.; Mazelle, C.; Brain, D.; Jakosky, B. M.

    2015-11-01

    Two Mars Atmosphere and Volatile EvolutioN magnetic field sensors sample the ambient magnetic field at the outer edge of each solar array. We characterized relatively minor spacecraft-generated magnetic fields using in-flight subsystem tests and spacecraft maneuvers. Dynamic spacecraft fields associated with the power subsystem (≤1 nT) are compensated for using spacecraft engineering telemetry to identify active solar array circuits and monitor their electrical current production. Static spacecraft magnetic fields are monitored using spacecraft roll maneuvers. Accuracy of measurement of the environmental magnetic field is demonstrated by comparison with field directions deduced from the symmetry properties of the electron distribution function measured by the Solar Wind Electron Analyzer. We map the bow shock, magnetic pileup boundary, the V × B convection electric field and ubiquitous proton cyclotron, and 1 Hz waves in the ion foreshock region.

  7. The investigation of fetal doses in mantle field irradiation.

    PubMed

    Karaçam, Songül Cavdar; Güralp, Onur Sahin; Oksüz, Didem Colpan; Koca, Ayse; Cepni, Ismail; Cepni, Kimia; Bese, Nuran

    2009-02-01

    To determine clinically the fetal dose from irradiation of Hodgkin's disease during pregnancy and to quantify the components of fetal dose using phantom measurements. The fetal dose was measured with phantom measurements using thermoluminescent dosemeters (TLDs). Phantom measurements were performed by simulating the treatment conditions on an anthropomorphic phantom. TLDs were placed on the phantom 41, 44, 46.5 and 49.5 cm from the centre of the treatment field. Two TLDs were placed on the surface of the phantom. The estimated total dose to all the TLDs ranged from 8.8 to 13.2 cGy for treatment with (60)Co and from 8.2 to 11.8 cGy for 4 MV photons. It was concluded that the doses in different sections were evaluated to investigate dose changes in different points and depths of fetal tissues in phantom. Precise planning and the use of supplemental fetal shielding may help reduce fetal exposure. PMID:19299479

  8. Limited field investigation for the 200-UP-1 operable unit

    SciTech Connect

    1996-11-01

    The 200-UP-1 Groundwater Operable Unit is located in the southern portion of the 200 West Area on the Hanford Site in Washington State. The operable unit is located adjacent to the 200-ZP-1 Groundwater Operable Unit and underlies a significant part of seven source operable units: 200-RO-1, 200-RO-2, 200-RO-3, 200-RO-4, 200-SS-2, 200-UP-2, and 200-UP-3. Remedial efforts in the 100-ZP-1 Operable Unit focus on addressing volatile organic contamination in the aquifer. The focus of the 200-UP-1 limited field investigation (LFI) is on contaminated aquifer soils and groundwater within its boundary, with the exception of uranium and technetium-99 plumes, which are addressed by an existing 200-UP-1 interim remedial measure (IRM). The LFI approach is driven by general and specific data needs required to refine the site conceptual model and conduct a risk assessment. Activities supporting the LFI include drilling, well construction, sampling and analysis, data validation, geologic and geophysical logging, aquifer testing, measuring depth to water, and evaluating geodetic survey and existing analytical data.

  9. Field Investigations of Evaporation from a Bare Soil

    NASA Astrophysics Data System (ADS)

    Evett, Steven Roy

    Selected components of the water and energy balances at the surface of a bare clay loam were measured at 57 locations in a 1 ha field. Spatial and temporal variability of these components were also studied. Components included evaporation, irrigation, moisture storage, sensible heat flux and long wave radiation. Sub-studies were conducted on irrigation uniformity under low pressure sprinklers; and, on steel versus plastic microlysimeters (ML) of various lengths. An energy balance model of evaporation, requiring minimal inputs, was developed and validated giving an r ^2 value of 0.78. Model improvements included an easy method of accurately estimating soil surface temperature at many points in a field, and an empirically fitted transfer coefficient function for the sensible heat flux from the reference dry soil. The omission of soil heat flux and reflected shortwave radiation terms was shown to reduce model accuracy. Steel ML underestimated cumulative evaporation compared to plastic ML at 20 and 30 cm lengths. Cumulative evaporation increased with ML length. The 10 and 20 cm ML were too short for use over multiple days but 30 cm ML may not be long enough for extended periods. Daily net soil heat flux for steel ML averaged 44% higher than that for both plastic ML and undisturbed field soil. Christiansen's uniformity coefficient (UCC) was close to 0.83 for each of 3 irrigations when measured by both catch cans and by profile water contents. But UCC for the change in storage due to irrigation averaged only 0.43 indicating than the high uniformity of profile water contents was more due to surface and subsurface redistribution than to the uniformity of application. Profile water contents and catch can depths were time invariant across at least 3 irrigations. Midday soil surface temperatures and daily evaporation were somewhat less time invariant. Variogram plots for evaporation and surface temperature showed mostly random behavior. Relative variograms represented well

  10. Investigations into High Temperature Components and Packaging

    SciTech Connect

    Marlino, L.D.; Seiber, L.E.; Scudiere, M.B.; M.S. Chinthavali, M.S.; McCluskey, F.P.

    2007-12-31

    The purpose of this report is to document the work that was performed at the Oak Ridge National Laboratory (ORNL) in support of the development of high temperature power electronics and components with monies remaining from the Semikron High Temperature Inverter Project managed by the National Energy Technology Laboratory (NETL). High temperature electronic components are needed to allow inverters to operate in more extreme operating conditions as required in advanced traction drive applications. The trend to try to eliminate secondary cooling loops and utilize the internal combustion (IC) cooling system, which operates with approximately 105 C water/ethylene glycol coolant at the output of the radiator, is necessary to further reduce vehicle costs and weight. The activity documented in this report includes development and testing of high temperature components, activities in support of high temperature testing, an assessment of several component packaging methods, and how elevated operating temperatures would impact their reliability. This report is organized with testing of new high temperature capacitors in Section 2 and testing of new 150 C junction temperature trench insulated gate bipolar transistor (IGBTs) in Section 3. Section 4 addresses some operational OPAL-GT information, which was necessary for developing module level tests. Section 5 summarizes calibration of equipment needed for the high temperature testing. Section 6 details some additional work that was funded on silicon carbide (SiC) device testing for high temperature use, and Section 7 is the complete text of a report funded from this effort summarizing packaging methods and their reliability issues for use in high temperature power electronics. Components were tested to evaluate the performance characteristics of the component at different operating temperatures. The temperature of the component is determined by the ambient temperature (i.e., temperature surrounding the device) plus the

  11. High field optical nonlinearities in gases

    NASA Astrophysics Data System (ADS)

    Cheng, Yu-Hsiang

    Optical femtosecond self-channeling in gases, also called femtosecond filamentation, has become an important area of research in high field nonlinear optics. Filamentation occurs when laser light self-focuses in a gas owing to self-induced nonlinearity, and then defocuses in the plasma generated by the self-focused beam. The result of this process repeating itself multiple times is an extended region of plasma formation. Filamentation studies have been motivated by the extremely broad range of applications, especially in air, including pulse compression, supercontinuum generation, broadband high power terahertz pulse generation, discharge triggering and guiding, and remote sensing. Despite the worldwide work in filamentation, the fundamental gas nonlinearities governing self-focusing had never been directly measured in the range of laser intensity up to and including the ionization threshold. This dissertation presents the first such measurements. We absolutely measured the temporal refractive index change of O2, N2, Ar, H2, D2 and N2O caused by highfield ultrashort optical pulses with single-shot supercontinuum spectral interferometry, cleanly separating for the first time the instantaneous electronic and delayed rotational nonlinear response in diatomic gases. We conclusively showed that a recent claim by several European groups that the optical bound electron nonlinearity saturates and goes negative is not correct. Such a phenomenon would preclude the need for plasma to provide the defocusing contribution for filamentation. Our results show that the 'standard model of filamentation', where the defocusing is provided by plasma, is correct. Finally, we demonstrated that high repetition rate femtosecond laser pulses filamenting in gases can generate long-lived gas density `holes' which persist on millisecond timescales, long after the plasma has recombined. Gas density decrements up to ~20% have been measured. The density hole refilling is dominated by thermal

  12. High-Gain High-Field Fusion Plasma

    PubMed Central

    Li, Ge

    2015-01-01

    A Faraday wheel (FW)—an electric generator of constant electrical polarity that produces huge currents—could be implemented in an existing tokamak to study high-gain high-field (HGHF) fusion plasma, such as the Experimental Advanced Superconducting Tokamak (EAST). HGHF plasma can be realized in EAST by updating its pulsed-power system to compress plasma in two steps by induction fields; high gains of the Lawson trinity parameter and fusion power are both predicted by formulating the HGHF plasma. Both gain rates are faster than the decrease rate of the plasma volume. The formulation is checked by earlier ATC tests. Good agreement between theory and tests indicates that scaling to over 10 T at EAST may be possible by two-step compressions with a compression ratio of the minor radius of up to 3. These results point to a quick new path of fusion plasma study, i.e., simulating the Sun by EAST. PMID:26507314

  13. High-density Au nanorod optical field-emitter arrays

    NASA Astrophysics Data System (ADS)

    Hobbs, R. G.; Yang, Y.; Keathley, P. D.; Swanwick, M. E.; Velásquez-García, L. F.; Kärtner, F. X.; Graves, W. S.; Berggren, K. K.

    2014-11-01

    We demonstrate the design, fabrication, characterization, and operation of high-density arrays of Au nanorod electron emitters, fabricated by high-resolution electron beam lithography, and excited by ultrafast femtosecond near-infrared radiation. Electron emission characteristic of multiphoton absorption has been observed at low laser fluence, as indicated by the power-law scaling of emission current with applied optical power. The onset of space-charge-limited current and strong optical field emission has been investigated so as to determine the mechanism of electron emission at high incident laser fluence. Laser-induced structural damage has been observed at applied optical fields above 5 GV m-1, and energy spectra of emitted electrons have been measured using an electron time-of-flight spectrometer.

  14. High-density Au nanorod optical field-emitter arrays.

    PubMed

    Hobbs, R G; Yang, Y; Keathley, P D; Swanwick, M E; Velásquez-Garcíia, L F; Kärtner, F X; Graves, W S; Berggren, K K

    2014-11-21

    We demonstrate the design, fabrication, characterization, and operation of high-density arrays of Au nanorod electron emitters, fabricated by high-resolution electron beam lithography, and excited by ultrafast femtosecond near-infrared radiation. Electron emission characteristic of multiphoton absorption has been observed at low laser fluence, as indicated by the power-law scaling of emission current with applied optical power. The onset of space-charge-limited current and strong optical field emission has been investigated so as to determine the mechanism of electron emission at high incident laser fluence. Laser-induced structural damage has been observed at applied optical fields above 5 GV m(-1), and energy spectra of emitted electrons have been measured using an electron time-of-flight spectrometer. PMID:25354583

  15. Near-field scanning optical microscopy investigations of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Dearo, Jessie Ann

    The Near-Field Scanning Optical Microscopy (NSOM) studies of novel, optically active, conjugated polymers are presented. NSOM is a relatively new technique which produces super resolution (˜50--100 nm) optical images simultaneously with topography. The conjugated polymer poly(p-phenylene vinylene) (PPV) and derivatives of PPV are organic semiconductor-like materials with interesting and unique optical properties. Derivatives of PPV have been used in LEDs and have potential in other optoelectronic devices. NSOM provides a tool for investigation of the photoluminescence, absorption/reflection, photo-dynamics and photoconductivity of films of PPV and PPV derivatives on the length scale that these properties are fundamentally defined. The NSOM experiments have revealed mesoscale domains (˜100 nm) of varying photoluminescence emission and average molecular order in drop cast films of PPV. NSOM of stretch-oriented PPV have shown domains of perpendicular molecular orientation with low photoluminescence emission. Near-field photoconductivity experiments of stretch-oriented PPV have correlated the mesoscale topography with the photoconductivity properties of the polymer. NSOM experiments of films of poly(2-methoxy, 5-(2'-(ethyl(hexyloxy)-p-phenylene vinylene) (MEH-PPV) have shown that there is mesoscale spatial inhomogeneity in the photo-oxidation process which reduces photoluminescence emission. NSOM has also been used to create nanoscale photo-patterning in MEH-PPV films. The NSOM experiments of blended films of MEH-PPV in polystyrene have shown mesoscale phase separation directly correlated to variations in the optical properties of the film. Derivatives of PPV, stretch-oriented in polyethylene, show photoluminescence intensity variations perpendicular and parallel to the stretch-direction correlated to topography features. As a complement to the NSOM studies of conjugated polymers, single polymer molecule experiments of MEH-PPV are also presented. The

  16. Plant Responses to High Frequency Electromagnetic Fields

    PubMed Central

    Vian, Alain; Davies, Eric; Gendraud, Michel; Bonnet, Pierre

    2016-01-01

    High frequency nonionizing electromagnetic fields (HF-EMF) that are increasingly present in the environment constitute a genuine environmental stimulus able to evoke specific responses in plants that share many similarities with those observed after a stressful treatment. Plants constitute an outstanding model to study such interactions since their architecture (high surface area to volume ratio) optimizes their interaction with the environment. In the present review, after identifying the main exposure devices (transverse and gigahertz electromagnetic cells, wave guide, and mode stirred reverberating chamber) and general physics laws that govern EMF interactions with plants, we illustrate some of the observed responses after exposure to HF-EMF at the cellular, molecular, and whole plant scale. Indeed, numerous metabolic activities (reactive oxygen species metabolism, α- and β-amylase, Krebs cycle, pentose phosphate pathway, chlorophyll content, terpene emission, etc.) are modified, gene expression altered (calmodulin, calcium-dependent protein kinase, and proteinase inhibitor), and growth reduced (stem elongation and dry weight) after low power (i.e., nonthermal) HF-EMF exposure. These changes occur not only in the tissues directly exposed but also systemically in distant tissues. While the long-term impact of these metabolic changes remains largely unknown, we propose to consider nonionizing HF-EMF radiation as a noninjurious, genuine environmental factor that readily evokes changes in plant metabolism. PMID:26981524

  17. Plant Responses to High Frequency Electromagnetic Fields.

    PubMed

    Vian, Alain; Davies, Eric; Gendraud, Michel; Bonnet, Pierre

    2016-01-01

    High frequency nonionizing electromagnetic fields (HF-EMF) that are increasingly present in the environment constitute a genuine environmental stimulus able to evoke specific responses in plants that share many similarities with those observed after a stressful treatment. Plants constitute an outstanding model to study such interactions since their architecture (high surface area to volume ratio) optimizes their interaction with the environment. In the present review, after identifying the main exposure devices (transverse and gigahertz electromagnetic cells, wave guide, and mode stirred reverberating chamber) and general physics laws that govern EMF interactions with plants, we illustrate some of the observed responses after exposure to HF-EMF at the cellular, molecular, and whole plant scale. Indeed, numerous metabolic activities (reactive oxygen species metabolism, α- and β-amylase, Krebs cycle, pentose phosphate pathway, chlorophyll content, terpene emission, etc.) are modified, gene expression altered (calmodulin, calcium-dependent protein kinase, and proteinase inhibitor), and growth reduced (stem elongation and dry weight) after low power (i.e., nonthermal) HF-EMF exposure. These changes occur not only in the tissues directly exposed but also systemically in distant tissues. While the long-term impact of these metabolic changes remains largely unknown, we propose to consider nonionizing HF-EMF radiation as a noninjurious, genuine environmental factor that readily evokes changes in plant metabolism. PMID:26981524

  18. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, James T.

    1997-01-01

    An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially cancelling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

  19. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, J.T.

    1998-05-05

    An apparatus and method are disclosed for generating homogeneous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 55 figs.

  20. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, J.T.

    1998-02-10

    An apparatus and method for generating homogeneous electromagnetic fields within a volume is disclosed. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 39 figs.

  1. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, James Terry

    1998-01-01

    An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

  2. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, James T.

    1998-01-01

    An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

  3. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, J.T.

    1997-06-24

    An apparatus and method are disclosed for generating homogeneous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 26 figs.

  4. Mechanical reinforcement for RACC cables in high magnetic background fields

    NASA Astrophysics Data System (ADS)

    Bayer, C. M.; Gade, P. V.; Barth, C.; Preuß, A.; Jung, A.; Weiß, K. P.

    2016-02-01

    Operable in liquid helium, liquid hydrogen or liquid nitrogen, high temperature superconductor (HTS) cables are investigated as future alternatives to low temperature superconductor (LTS) cables in magnet applications. Different high current HTS cable concepts have been developed and optimized in the last years—each coming with its own benefits and challenges. As the Roebel assembled coated conductor (RACC) is the only fully transposed HTS cable investigated so far, it is attractive for large scale magnet and accelerator magnet applications when field quality and alternating current (AC) losses are of highest importance. However, due to its filamentary character, the RACC is very sensitive to Lorentz forces. In order to increase the mechanical strength of the RACC, each of the HTS strands was covered by an additional copper tape. After investigating the maximum applicable transverse pressure on the strand composition, the cable was clamped into a stainless steel structure to reinforce it against Lorentz forces. A comprehensive test has been carried out in the FBI facility at 4.2 K in a magnetic field of up to 12 T. This publication discusses the maximum applicable pressure as well as the behaviour of the RACC cable as a function of an external magnetic field.

  5. High magnetic field induced changes of gene expression in arabidopsis

    PubMed Central

    Paul, Anna-Lisa; Ferl, Robert J; Meisel, Mark W

    2006-01-01

    Background High magnetic fields are becoming increasingly prevalent components of non-invasive, biomedical imaging tools (such as MRI), thus, an understanding of the molecular impacts associated with these field strengths in biological systems is of central importance. The biological impact of magnetic field strengths up to 30 Tesla were investigated in this study through the use of transgenic Arabidopsis plants engineered with a stress response gene consisting of the alcohol dehydrogenase (Adh) gene promoter driving the β-glucuronidase (GUS) gene reporter. Methods Magnetic field induced Adh/GUS activity was evaluated with histochemical staining to assess tissue specific expression and distribution, and with quantitative, spectrofluometric assays to measure degree of activation. The evaluation of global changes in the Arabidopsis genome in response to exposure to high magnetic fields was facilitated with Affymetrix Gene Chip microarrays. Quantitative analyses of gene expression were performed with quantitative real-time polymerase-chain-reaction (qRT-PCR). Results Field strengths in excess of about 15 Tesla induce expression of the Adh/GUS transgene in the roots and leaves. From the microarray analyses that surveyed 8000 genes, 114 genes were differentially expressed to a degree greater than 2.5 fold over the control. These results were quantitatively corroborated by qRT-PCR examination of 4 of the 114 genes. Conclusion The data suggest that magnetic fields in excess of 15 Tesla have far-reaching effect on the genome. The wide-spread induction of stress-related genes and transcription factors, and a depression of genes associated with cell wall metabolism, are prominent examples. The roles of magnetic field orientation of macromolecules and magnetophoretic effects are discussed as possible factors that contribute to the mounting of this response. PMID:17187667

  6. High-Throughput Investigation of Delafossite materials

    NASA Astrophysics Data System (ADS)

    Haycock, Barry; Kylee Underwood, M.; Lekse, Jonathan; Matranga, Christopher; Lewis, James P.

    2013-03-01

    We present the application of high-throughput calculations to the intriguing problem of the forbidden optical transition in the CuGa1-xFexO2 delafossites, which is prototypical of many delafossite systems. When 5% or more of the Ga sites are replaced with Fe, there is a sudden shift to an optical band gap of 1.5eV from 2.5eV. Using high-throughput calculations and data mining techniques, we show the most likely positional configurations for x = 0.00 through x = 0.10 of the Fe atoms relative to one another. Implications of this result and applications of the techniques used are discussed, including the development of candidate materials via high-throughput analysis of constituent search-space. Funded by the National Science Foundation through NSF DMR 09-03225 and a subcontract from NETL (URS RES) for Work Activity 0004000.6.600.007.002.420.000.005 ARRA ICMI Project.

  7. First Results of the MAVEN Magnetic Field Investigation

    NASA Astrophysics Data System (ADS)

    Connerney, J. E. P.; Espley, J. R.; DiBraccio, G. A.; Gruesbeck, J.; Mitchell, D. L.; Halekas, J. S.; Mazelle, C. X.; Brain, D.; Jakosky, B. M.; Oliversen, R. J.

    2015-12-01

    The MAVEN spacecraft approaches the end of its first year in orbit, systematically mapping the interaction region about Mars with a focus on atmospheric escape. The comprehensive instrument suite aboard MAVEN has busied itself in mapping the magnetosphere, magnetosheath, magnetotail, and extended atmospheric corona in near-Mars space. MAVEN carries two magnetic field sensors (fluxgate magnetometers) as part of the particles and fields package (PFP); they sample the ambient magnetic field from a vantage point on at the outer edge of each solar array. We characterized relatively minor spacecraft-generated magnetic fields using a series of in-flight subsystem tests and spacecraft maneuvers. Dynamic spacecraft fields (≤ 1 nT) associated with the operation of specific solar array circuits are compensated for using spacecraft engineering telemetry to identify active circuits and monitor their electrical current production. Static spacecraft magnetic fields are monitored using spacecraft roll maneuvers. Accuracy of measurement of the environmental magnetic field is demonstrated by comparison with field directions deduced from the symmetry properties of the electron distribution function measured by the Solar Wind Electron Analyzer (SWEA). We compile magnetometer observations to characterize intense crustal magnetic fields, the solar wind interaction with Mars, and ubiquitous proton cyclotron and 1-Hz waves in the upstream solar wind (ion foreshock region). The figure below compiles observations of magnetic fluctuations obtained by MAVEN in near-Mars space. The map of magnetic fluctuations reveals the statistical extent of the magnetosheath, confined between the bow shock and the magnetic pile-up region.

  8. Penetration dynamics of a magnetic field pulse into high-? superconductors

    NASA Astrophysics Data System (ADS)

    Meerovich, V.; Sinder, M.; Sokolovsky, V.; Goren, S.; Jung, G.; Shter, G. E.; Grader, G. S.

    1996-12-01

    The penetration of a magnetic field pulse into a high-0953-2048/9/12/004/img9 superconducting plate is investigated experimentally and theoretically. It follows from our experiments that the threshold of penetration increases with increasing amplitude and/or decreasing duration of the applied pulse. The penetrating field continues to grow as the applied magnetic field decreases. The peculiarities observed are explained in the framework of the extended critical state model. It appears that the deviations from Bean's classical critical state model are characterized by a parameter equal to the square of the ratio of plate thickness to skin depth. The applicability of the classical critical state model is restricted by the condition that this parameter is much less than 1. This condition is also the criterion for the applicability of pulse methods of critical current measurements.

  9. High-magnetic-field MHD-generator program

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Eustis, R. H.; Mitchner, M.; Self, S. A.; Koester, J. K.; Kruger, C. H.

    1981-07-01

    Progress in an experimental and theoretical program designed to investigate MHD channel phenomena which are important at high magnetic fields is described. The areas of research include nonuniformity effects, boundary layers, Hall field breakdown, the effects of electrode configuration and current concentrations, and studies of steady-state combustion disk and linear channels in an existing 6 Tesla magnet of small dimensions. In the study of the effects of nonuniformities, experiments were performed to test a multi-channel, fiber optics diagnostic system that yields time-resolved temperature profiles in an MHD chanel. For the study of magneto-acoustic fluctuation phenomena, a one dimensional model was developed to describe the performance of a non-ideal MHD generator with a generalized electrical configuration. A two dimensional MHD computer code was developed which predicts the dependence on electrode and insulator dimensions of the onset of interelectrode Hall field breakdown, as initiated either by breakdown in the insulator or in the plasma.

  10. High magnetic field ohmically decoupled non-contact technology

    DOEpatents

    Wilgen, John [Oak Ridge, TN; Kisner, Roger [Knoxville, TN; Ludtka, Gerard [Oak Ridge, TN; Ludtka, Gail [Oak Ridge, TN; Jaramillo, Roger [Knoxville, TN

    2009-05-19

    Methods and apparatus are described for high magnetic field ohmically decoupled non-contact treatment of conductive materials in a high magnetic field. A method includes applying a high magnetic field to at least a portion of a conductive material; and applying an inductive magnetic field to at least a fraction of the conductive material to induce a surface current within the fraction of the conductive material, the surface current generating a substantially bi-directional force that defines a vibration. The high magnetic field and the inductive magnetic field are substantially confocal, the fraction of the conductive material is located within the portion of the conductive material and ohmic heating from the surface current is ohmically decoupled from the vibration. An apparatus includes a high magnetic field coil defining an applied high magnetic field; an inductive magnetic field coil coupled to the high magnetic field coil, the inductive magnetic field coil defining an applied inductive magnetic field; and a processing zone located within both the applied high magnetic field and the applied inductive magnetic field. The high magnetic field and the inductive magnetic field are substantially confocal, and ohmic heating of a conductive material located in the processing zone is ohmically decoupled from a vibration of the conductive material.

  11. FIELD INVESTIGATION OF BIOLOGICAL TOILET SYSTEMS AND GREY WATER TREATMENT

    EPA Science Inventory

    The objective of the field program was to determine the operational characteristics and overall acceptability of popular models of biological toilets and a few select grey water systems. A field observation scheme was devised to take advantage of in-use sites throughout the State...

  12. Laboratory and field investigations of marsh edge erosion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter presents the laboratory experiments and field observations of marsh edge erosion. The marsh retreat rate in a field study site in Terrebonne Bay, Louisiana, was measured using GPS systems and aerial photographs. The wave environment was also measured in order to correlate the marsh edge...

  13. Transient magnetic field signatures at high latitudes

    SciTech Connect

    Sibeck, D.G. )

    1993-01-01

    We survey GOES 2/5/6 geosynchronous and Huancayo, Peru, ground magnetometer observations at the times of 70 transient (2-10 min) events recorded at South Pole Station, Antarctica. The simultaneous observations indicate that most South Pole events correspond to sudden sharp variations in the equatorial magnetospheric and low-latitude ground magnetic field. The exceptions occur when the South Pole events have weak amplitudes and/or Huancayo and GOES 2/5/6 are far from local noon. The corresponding features observed at GOES 5 and GOES 6 are generally similar, with a lag indicating antisunward motion. A similar antisunward motion may be inferred from the ground observations themselves. On a case-by-case and statistical basis, the characteristics of the events observed in South Pole ground magnetograms resemble those previously interpreted as sudden impulse and sudden storm commencement signatures at other high-latitude stations. These observations suggest that the transient events at South Pole form part of the magnetospheric and ionospheric response to a sudden change in the fraction of the solar wind dynamic pressure applied to the magnetosphere. 57 refs., 14 figs.

  14. Theoretical and Computational Investigation of High-Brightness Beams

    SciTech Connect

    Chen, Chiping

    2013-11-30

    Theoretical and computational investigations of adiabatic thermal beams have been carried out in parameter regimes relevant to the development of advanced high-brightness, high-power accelerators for high-energy physics research and for various applications such as light sources. Most accelerator applications require high-brightness beams. This is true for high-energy accelerators such as linear colliders. It is also true for energy recovery linacs (ERLs) and free electron lasers (FELs) such as x-ray free electron lasers (XFELs). The breakthroughs and highlights in our research in the period from February 1, 2013 to November 30, 2013 were: a) Completion of a preliminary theoretical and computational study of adiabatic thermal Child-Langmuir flow (Mok, 2013); and b) Presentation of an invited paper entitled ?Adiabatic Thermal Beams in a Periodic Focusing Field? at Space Charge 2013 Workshop, CERN, April 16-19, 2013 (Chen, 2013). In this report, an introductory background for the research project is provided. Basic theory of adiabatic thermal Child-Langmuir flow is reviewed. Results of simulation studies of adiabatic thermal Child-Langmuir flows are discussed.

  15. Investigation of mechanosensation in C. elegans using light field calcium imaging.

    PubMed

    Shaw, Michael; Elmi, Muna; Pawar, Vijay; Srinivasan, Mandayam A

    2016-07-01

    We describe a new experimental approach to investigate touch sensation in the model organism C. elegans using light field deconvolution microscopy. By combining fast volumetric image acquisition with controlled indentation of the organism using a high sensitivity force transducer, we are able to simultaneously measure activity in multiple touch receptor neurons expressing the calcium ion indicator GCaMP6s. By varying the applied mechanical stimulus we show how this method can be used to quantify touch sensitivity in C. elegans. We describe some of the challenges of performing light field calcium imaging in moving samples and demonstrate that they can be overcome by simple data processing. PMID:27446713

  16. Investigation of mechanosensation in C. elegans using light field calcium imaging

    PubMed Central

    Shaw, Michael; Elmi, Muna; Pawar, Vijay; Srinivasan, Mandayam A.

    2016-01-01

    We describe a new experimental approach to investigate touch sensation in the model organism C. elegans using light field deconvolution microscopy. By combining fast volumetric image acquisition with controlled indentation of the organism using a high sensitivity force transducer, we are able to simultaneously measure activity in multiple touch receptor neurons expressing the calcium ion indicator GCaMP6s. By varying the applied mechanical stimulus we show how this method can be used to quantify touch sensitivity in C. elegans. We describe some of the challenges of performing light field calcium imaging in moving samples and demonstrate that they can be overcome by simple data processing. PMID:27446713

  17. Investigation of Spherical-Wave-Initiated Flow Fields Around Bodies

    NASA Technical Reports Server (NTRS)

    McFarland, Donald R.

    1959-01-01

    Measurements of the velocity flow fields and vortex movements have been made about various simple blunt models undergoing spherical blast waves with a positive overpressure of 4 pounds per square inch. A bullet-optical method was used to determine flow velocities and is applied to velocity fields in which the gradients are largely normal to the free-stream direction. The velocity flow fields are shown at various flow times following passage of the blast front for different models. Vortex movements with time are compared for square-bar models of various aspect ratios. Corner sharpness had no discernible effect on the overall disturbed velocity fields or vortex movements for the square-box models used.

  18. Theoretical investigation of hyperfine field parameters through mossbauer gamma ray

    SciTech Connect

    Ali, Sikander; Hashim, Mohd

    2012-06-05

    When a Mossbauer gamma-ray emitting or absorbing nucleus is placed in a crystalline environment, the quadrupole moment of the nucleus interacts with the electric field gradient set up by the ligands around it. In the transition |7/2>{yields}|5/2> twelve lines are obtained. Applying the multipole radiation field theory and density matrix formalism, the determinant of coherency matrix, intensity and degree of polarization have been calculated for each line.

  19. Policy Forum: Studying Eyewitness Investigations in the Field

    PubMed Central

    Dawes, Robyn; Jacoby, Larry L.; Kahneman, Daniel; Lempert, Richard; Roediger, Henry L.; Rosenthal, Robert

    2007-01-01

    This article considers methodological issues arising from recent efforts to provide field tests of eyewitness identification procedures. We focus in particular on a field study (Mecklenburg 2006) that examined the “double blind, sequential” technique, and consider the implications of an acknowledged methodological confound in the study. We explain why the confound has severe consequences for assessing the real-world implications of this study. PMID:17610149

  20. Rotating magnetic field current drive of high-temperature field reversed configurations with high {zeta} scaling

    SciTech Connect

    Guo, H. Y.; Hoffman, A. L.; Milroy, R. D.

    2007-11-15

    Greatly reduced recycling and impurity ingestion in the Translation, Confinement, and Sustainment--Upgrade (TCSU) device has allowed much higher plasma temperatures to be achieved in the field reversed configurations (FRC) under rotating magnetic field (RMF) formation and sustainment. The hotter plasmas have higher magnetic fields and much higher diamagnetic electron rotation rates so that the important ratio of average electron rotation frequency to RMF frequency, called {zeta}, approaches unity, for the first time, in TCSU. A large fraction of the RMF power is absorbed by an as yet unexplained (anomalous) mechanism directly proportional to the square of the RMF magnitude. It becomes of relatively lesser significance as the FRC current increases, and simple resistive heating begins to dominate, but the anomalous absorption is useful for initial plasma heating. Measurements of total absorbed power, and comparisons of applied RMF torque to torque on the electrons due to electron-ion friction under high-{zeta} operation, over a range of temperatures and fields, have allowed the separation of the classical Ohmic and anomalous heating to be inferred, and cross-field plasma resistivities to be calculated.

  1. MO-G-BRF-09: Investigating Magnetic Field Dose Effects in Mice: A Monte Carlo Study

    SciTech Connect

    Rubinstein, A; Guindani, M; Followill, D; Melancon, A; Hazle, J; Court, L

    2014-06-15

    Purpose: In MRI-linac treatments, radiation dose distributions are affected by magnetic fields, especially at high-density/low-density interfaces. Radiobiological consequences of magnetic field dose effects are presently unknown; therefore, preclinical studies are needed to ensure the safe clinical use of MRI-linacs. This study investigates the optimal combination of beam energy and magnetic field strength needed for preclinical murine studies. Methods: The Monte Carlo code MCNP6 was used to simulate the effects of a magnetic field when irradiating a mouse-sized lung phantom with a 1.0cmx1.0cm photon beam. Magnetic field effects were examined using various beam energies (225kVp, 662keV[Cs-137], and 1.25MeV[Co-60]) and magnetic field strengths (0.75T, 1.5T, and 3T). The resulting dose distributions were compared to Monte Carlo results for humans with various field sizes and patient geometries using a 6MV/1.5T MRI-linac. Results: In human simulations, the addition of a 1.5T magnetic field caused an average dose increase of 49% (range:36%–60%) to lung at the soft tissue-to-lung interface and an average dose decrease of 30% (range:25%–36%) at the lung-to-soft tissue interface. In mouse simulations, the magnetic fields had no effect on the 225kVp dose distribution. The dose increases for the Cs-137 beam were 12%, 33%, and 49% for 0.75T, 1.5T, and 3.0T magnetic fields, respectively while the dose decreases were 7%, 23%, and 33%. For the Co-60 beam, the dose increases were 14%, 45%, and 41%, and the dose decreases were 18%, 35%, and 35%. Conclusion: The magnetic field dose effects observed in mouse phantoms using a Co-60 beam with 1.5T or 3T fields and a Cs-137 beam with a 3T field compare well with those seen in simulated human treatments with an MRI-linac. These irradiator/magnet combinations are suitable for preclinical studies investigating potential biological effects of delivering radiation therapy in the presence of a magnetic field. Partially funded by Elekta.

  2. Investigation Into The Effectiveness of The JLAB High Pressure Rinse System

    SciTech Connect

    John Mammosser; Timothy Rothgeb; Tong Wang; Andy Wu

    2003-05-01

    As part of a study to reduce field emission in Superconducting radio frequency cavities, an investigation into the effectiveness of the Jefferson Lab's High Pressure Rinse (HPR) system is underway. This paper describes discoveries from this investigation, the procedural changes made during this investigation, current vertical test results and further plans for improvements and monitoring.

  3. Threats to ultra-high-field MRI

    NASA Astrophysics Data System (ADS)

    Le Bihan, Denis

    2009-08-01

    In 2004 the European Commission (EC) adopted a directive restricting occupational exposure to electromagnetic fields. This directive (2004/40/CE), which examines the possible health risks of the electromagnetic fields from mobile phones, Wi-Fi, Bluetooth and other devices, concluded that upper limits on radiation and applied electromagnetic fields are necessary to prevent workers from suffering any undue acute health effects. But although not initially intended, the biggest impact of the directive could be on magnetic resonance imaging (MRI), which is used in hospitals worldwide to produce images of unrivalled quality of the brain and other soft tissues.

  4. Investigation of Reddening in Fields of the SMASH Survey

    NASA Astrophysics Data System (ADS)

    Juelfs, Elizabeth A.; Olsen, Knut A.; SMASH Team

    2016-01-01

    We present dust extinction maps derived from eight fields in the Survey of the MAgellanic Stellar History (SMASH), a survey that is imaging 480 deg^2 of the southern sky in DES-ugriz with the CTIO 4-m Blanco telescope and the Dark Energy Camera (DECam). We derive the extinction due to dust using fits to the stellar locus of stars brighter than g=21 in color-color diagrams, and explore the spatial distribution of the extinction within each of the fields. We compare our results to the extinction map of Schlegel, Finkbeiner, & Davis (1998), and find generally good agreement. We describe plans to measure the three-dimensional distribution of extinction in these fields using fainter stars and background galaxies as tracers. Juelfs was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program (AST-1262829).

  5. An investigation into the induced electric fields from transcranial magnetic stimulation

    NASA Astrophysics Data System (ADS)

    Hadimani, Ravi; Lee, Erik; Duffy, Walter; Waris, Mohammed; Siddiqui, Waquar; Islam, Faisal; Rajamani, Mahesh; Nathan, Ryan; Jiles, David; David C Jiles Team; Walter Duffy Collaboration

    Transcranial magnetic stimulation (TMS) is a promising tool for noninvasive brain stimulation that has been approved by the FDA for the treatment of major depressive disorder. To stimulate the brain, TMS uses large, transient pulses of magnetic field to induce an electric field in the head. This transient magnetic field is large enough to cause the depolarization of cortical neurons and initiate a synaptic signal transmission. For this study, 50 unique head models were created from MRI images. Previous simulation studies have primarily used a single head model, and thus give a limited image of the induced electric field from TMS. This study uses finite element analysis simulations on 50 unique, heterogeneous head models to better investigate the relationship between TMS and the electric field induced in brain tissues. Results showed a significant variation in the strength of the induced electric field in the brain, which can be reasonably predicted by the distance from the TMS coil to the stimulated brain. Further, it was seen that some models had high electric field intensities in over five times as much brain volume as other models.

  6. An X-ray Investigation of the NGC 346 Field in the SMC (2): The Field Population

    NASA Technical Reports Server (NTRS)

    Naze, Y.; Hartwell, J. M.; Stevens, I. R.; Manfroid, J.; Marchenko. S.; Corcoran, M. F.; Moffat, A. F. J.; Skalkowski, G.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present results from a Chandra observation of the NGC 346 cluster, the ionizing source of N66, the most luminous H II region and the largest star formation region in the SMC. In the first part of this investigation, we have analysed the X-ray properties of the cluster itself and the remarkable star HD 5980. But the field contains additional objects of interest. In total, 79 X-ray point sources were detected in the Chandra observation and we investigate here their characteristics in details. The sources possess rather high HRs, and their cumulative luminosity function is steeper than the SMC's trend. Their absorption columns suggest that most of the sources belong to NGC 346. Using new UBVRI imaging with the ESO 2.2m telescope, we also discovered possible counterparts for 36 of these X-ray sources. Finally, some objects show X-ray and/or optical variability, and thus need further monitoring.

  7. Extending methods: using Bourdieu's field analysis to further investigate taste

    NASA Astrophysics Data System (ADS)

    Schindel Dimick, Alexandra

    2015-06-01

    In this commentary on Per Anderhag, Per-Olof Wickman and Karim Hamza's article Signs of taste for science, I consider how their study is situated within the concern for the role of science education in the social and cultural production of inequality. Their article provides a finely detailed methodology for analyzing the constitution of taste within science education classrooms. Nevertheless, because the authors' socially situated methodology draws upon Bourdieu's theories, it seems equally important to extend these methods to consider how and why students make particular distinctions within a relational context—a key aspect of Bourdieu's theory of cultural production. By situating the constitution of taste within Bourdieu's field analysis, researchers can explore the ways in which students' tastes and social positionings are established and transformed through time, space, place, and their ability to navigate the field. I describe the process of field analysis in relation to the authors' paper and suggest that combining the authors' methods with a field analysis can provide a strong methodological and analytical framework in which theory and methods combine to create a detailed understanding of students' interest in relation to their context.

  8. Apparatus having reduced mechanical forces for supporting high magnetic fields

    DOEpatents

    Prueitt, Melvin L.; Mueller, Fred M.; Smith, James L.

    1991-01-01

    The present invention identifies several configurations of conducting elements capable of supporting extremely high magnetic fields suitable for plasma confinement, wherein forces experienced by the conducting elements are significantly reduced over those which are present as a result of the generation of such high fields by conventional techniques. It is anticipated that the use of superconducting materials will both permit the attainment of such high fields and further permit such fields to be generated with vastly improved efficiency.

  9. Scanning tunnelling microscopy in extreme fields: very low temperature, high magnetic field, and extreme high vacuum

    NASA Astrophysics Data System (ADS)

    Sagisaka, Keisuke; Kitahara, Masayo; Fujita, Daisuke; Kido, Giyuu; Koguchi, Nobuyuki

    2004-06-01

    We present the performance of our newly developed very-low-temperature scanning tunnelling microscope (VLT-STM). This system can operate with high spatial and energy resolution at temperatures down to 350 mK, and in a magnetic field up to 11 T. The uniqueness of our VLT-STM is that the system possesses extreme-high-vacuum chambers (XHV) ({\\sim } 10^{-10} Pa). System operation ranges from sample preparation, such as cleaning and deposition, to observations in an extremely clean environment. XHV will have a significant impact within material sciences, particularly when treating a semiconductor surface. Test results have revealed STM images obtained below 1 K and with atomic resolution of highly oriented pyrolytic graphite (HOPG), Si(100) dimers, and Au(111) surfaces. Our Si(100) experiments are the first atomically-resolved STM images of the semiconductor surface obtained below 1 K. The results of those tests have conclusively determined its true ground state structure—a subject under debate for many years. Some of the STM images acquired in a high magnetic field are included in this paper. The XHV-VLT-STM system is state-of-the-art and a very powerful instrument for exploration of the nano-sciences.

  10. High magnetic field induced otolith fusion in the zebrafish larvae.

    PubMed

    Pais-Roldán, Patricia; Singh, Ajeet Pratap; Schulz, Hildegard; Yu, Xin

    2016-01-01

    Magnetoreception in animals illustrates the interaction of biological systems with the geomagnetic field (geoMF). However, there are few studies that identified the impact of high magnetic field (MF) exposure from Magnetic Resonance Imaging (MRI) scanners (>100,000 times of geoMF) on specific biological targets. Here, we investigated the effects of a 14 Tesla MRI scanner on zebrafish larvae. All zebrafish larvae aligned parallel to the B0 field, i.e. the static MF, in the MRI scanner. The two otoliths (ear stones) in the otic vesicles of zebrafish larvae older than 24 hours post fertilization (hpf) fused together after the high MF exposure as short as 2 hours, yielding a single-otolith phenotype with aberrant swimming behavior. The otolith fusion was blocked in zebrafish larvae under anesthesia or embedded in agarose. Hair cells may play an important role on the MF-induced otolith fusion. This work provided direct evidence to show that high MF interacts with the otic vesicle of zebrafish larvae and causes otolith fusion in an "all-or-none" manner. The MF-induced otolith fusion may facilitate the searching for MF sensors using genetically amenable vertebrate animal models, such as zebrafish. PMID:27063288

  11. High magnetic field induced otolith fusion in the zebrafish larvae

    PubMed Central

    Pais-Roldán, Patricia; Singh, Ajeet Pratap; Schulz, Hildegard; Yu, Xin

    2016-01-01

    Magnetoreception in animals illustrates the interaction of biological systems with the geomagnetic field (geoMF). However, there are few studies that identified the impact of high magnetic field (MF) exposure from Magnetic Resonance Imaging (MRI) scanners (>100,000 times of geoMF) on specific biological targets. Here, we investigated the effects of a 14 Tesla MRI scanner on zebrafish larvae. All zebrafish larvae aligned parallel to the B0 field, i.e. the static MF, in the MRI scanner. The two otoliths (ear stones) in the otic vesicles of zebrafish larvae older than 24 hours post fertilization (hpf) fused together after the high MF exposure as short as 2 hours, yielding a single-otolith phenotype with aberrant swimming behavior. The otolith fusion was blocked in zebrafish larvae under anesthesia or embedded in agarose. Hair cells may play an important role on the MF-induced otolith fusion. This work provided direct evidence to show that high MF interacts with the otic vesicle of zebrafish larvae and causes otolith fusion in an “all-or-none” manner. The MF-induced otolith fusion may facilitate the searching for MF sensors using genetically amenable vertebrate animal models, such as zebrafish. PMID:27063288

  12. Polarized neutron reflectometry in high magnetic fields

    SciTech Connect

    Fritzsche, H.

    2005-11-15

    A simple method is described to maintain the polarization of a neutron beam on its way through the large magnetic stray fields produced by a vertical field of a cryomagnet with a split-coil geometry. The two key issues are the proper shielding of the neutron spin flippers and an additional radial field component in order to guide the neutron spin through the region of the null point (i.e., point of reversal for the vertical field component). Calculations of the neutron's spin rotation as well as polarized neutron reflectometry experiments on an ErFe{sub 2}/DyFe{sub 2} multilayer show the perfect performance of the used setup. The recently commissioned cryomagnet M5 with a maximum vertical field of up to 7.2 T in asymmetric mode for polarized neutrons and 9 T in symmetric mode for unpolarized neutrons was used on the C5 spectrometer in reflectometry mode, at the NRU reactor in Chalk River, Canada.

  13. High-Field Superconducting Magnets Supporting PTOLEMY

    NASA Astrophysics Data System (ADS)

    Hopkins, Ann; Luo, Audrey; Osherson, Benjamin; Gentile, Charles; Tully, Chris; Cohen, Adam

    2013-10-01

    The Princeton Tritium Observatory for Light, Early Universe, Massive Neutrino Yield (PTOLEMY) is an experiment planned to collect data on Big Bang relic neutrinos, which are predicted to be amongst the oldest and smallest particles in the universe. Currently, a proof-of-principle prototype is being developed at Princeton Plasma Physics Laboratory to test key technologies associated with the experiment. A prominent technology in the experiment is the Magnetic Adiabatic Collimation with an Electrostatic Filter (MAC-E filter), which guides tritium betas along magnetic field lines generated by superconducting magnets while deflecting those of lower energies. B field mapping is performed to ensure the magnets produce a minimum field at the midpoint of the configuration of the magnets and to verify accuracy of existing models. Preliminary tests indicate the required rapid decrease in B field strength from the bore of the more powerful 3.35 T magnet, with the field dropping to 0.18 T approximately 0.5 feet from the outermost surface of the magnet.

  14. Field investigation source area ST58 old Quartermaster service station, Eielson Air Force Base, Alaska

    SciTech Connect

    Liikala, T.L.; Evans, J.C.

    1995-01-01

    Source area ST58 is the site of the old Quartermaster service station at Eielson Air Force Base, Alaska. The source area is one of several Source Evaluation Report sites being investigated by Pacific Northwest Laboratory for the US Air Force as candidates for no further remedial action, interim removal action, or a remedial investigation/feasibility study under a Federal Facilities Agreement. The purpose of this work was to characterize source area ST58 and excavate the most contaminated soils for use in composting treatability studies. A field investigation was conducted to determine the nature and extent of soil contamination. The field investigation entailed a records search; grid node location, surface geophysical, and soil gas surveys; and test pit soil sampling. Soil excavation followed based on the results of the field investigation. The site was backfilled with clean soil. Results from this work indicate close spatial correlation between screening instruments, used during the field investigation and soil excavation, and laboratory analyses. Gasoline was identified as the main subsurface contaminant based on the soil gas surveys and test pit soil sampling. A center of contamination was located near the northcentral portion of the source area, and a center was located in the northwestern comer. The contamination typically occurred near or below a former soil horizon probably as a result of surface spills and leaks from discontinuities and/or breaks in the underground piping. Piping locations were delineated during the surface geophysical surveys and corresponded very well to unscaled drawings of the site. The high subsurface concentrations of gasoline detected in the northwestern comer of the source area probably reflect ground-water contamination and/or possibly floating product.

  15. Aluminum doping studies on high field ZnO varistors

    SciTech Connect

    Kimball, K.M.; Doughty, D.H.

    1987-08-01

    We have investigated the effect of Al doping on the physical and electronic properties of high field ZnO varistors. For this study, varistors containing 98.94 m/o ZnO, 0.25 m/o CoO, 0.25 m/o MnO, 0.56 m/o Bi/sub 2/O/sub 3/ and 0 to 200 ppM Al were prepared from powders obtained from solution precipitation techniques. Because of the amphoteric nature of aluminum oxides, precise control of pH and metal concentrations was necessary to assure complete incorporation of dopants. We observed inhibition of grain growth during sintering of varistor pellets at aluminum concentrations of 50 ppM and above. The measured electrical properties show increased switching fields and increased nonlinearity coefficients for Al doping levels of 50 to 200 ppM.

  16. Investigation of defect-induced abnormal body current in fin field-effect-transistors

    SciTech Connect

    Liu, Kuan-Ju; Tsai, Jyun-Yu; Lu, Ying-Hsin; Liu, Xi-Wen; Chang, Ting-Chang; Chen, Ching-En; Yang, Ren-Ya; Cheng, Osbert; Huang, Cheng-Tung

    2015-08-24

    This letter investigates the mechanism of abnormal body current at the linear region in n-channel high-k/metal gate stack fin field effect transistors. Unlike body current, which is generated by impact ionization at high drain voltages, abnormal body current was found to increase with decreasing drain voltages. Notably, the unusual body leakage only occurs in three-dimensional structure devices. Based on measurements under different operation conditions, the abnormal body current can be attributed to fin surface defect-induced leakage current, and the mechanism is electron tunneling to the fin via the defects, resulting in holes left at the body terminal.

  17. 7 CFR 12.22 - Highly erodible field determination criteria.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Highly erodible field determination criteria. 12.22 Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria....

  18. 7 CFR 12.22 - Highly erodible field determination criteria.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 1 2011-01-01 2011-01-01 false Highly erodible field determination criteria. 12.22 Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria....

  19. 7 CFR 12.22 - Highly erodible field determination criteria.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 1 2013-01-01 2013-01-01 false Highly erodible field determination criteria. 12.22 Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria....

  20. 7 CFR 12.22 - Highly erodible field determination criteria.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 1 2014-01-01 2014-01-01 false Highly erodible field determination criteria. 12.22 Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria....

  1. 7 CFR 12.22 - Highly erodible field determination criteria.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 1 2012-01-01 2012-01-01 false Highly erodible field determination criteria. 12.22 Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria....

  2. Investigation of a high power electromagnetic pulse source.

    PubMed

    Wang, Yuwei; Chen, Dongqun; Zhang, Jiande; Cao, Shengguang; Li, Da; Liu, Chebo

    2012-09-01

    A high power electromagnetic pulse source with a resonant antenna driven by a compact power supply was investigated in this paper. To match the impedance of the resonant antenna and initial power source, a compact power conditioning circuit based on electro exploding opening switch (EEOS) and pulsed transformer was adopted. In the preliminary experiments, an impulse capacitor was used to drive the system. With the opening of the EEOS at the current of 15 kA flowing trough the primary of the transformer, the resonant antenna was rapidly charged to about -370 kV within a time of about 100 ns. When the switch in the resonant antenna closed at the charging voltage of about -202 kV, the peak intensity of the detected electric field at a distance of about 10 m from the center of the source was 7.2 kV∕m. The corresponding peak power of the radiated electromagnetic field reached 76 MW, while the total radiated electromagnetic energy was about 0.65 J. The total energy efficiency of the resonant antenna was about 22% which can be improved by increasing the closing rapidity of the switch in the antenna. PMID:23020399

  3. Investigation of a high power electromagnetic pulse source

    NASA Astrophysics Data System (ADS)

    Wang, Yuwei; Chen, Dongqun; Zhang, Jiande; Cao, Shengguang; Li, Da; Liu, Chebo

    2012-09-01

    A high power electromagnetic pulse source with a resonant antenna driven by a compact power supply was investigated in this paper. To match the impedance of the resonant antenna and initial power source, a compact power conditioning circuit based on electro exploding opening switch (EEOS) and pulsed transformer was adopted. In the preliminary experiments, an impulse capacitor was used to drive the system. With the opening of the EEOS at the current of 15 kA flowing trough the primary of the transformer, the resonant antenna was rapidly charged to about -370 kV within a time of about 100 ns. When the switch in the resonant antenna closed at the charging voltage of about -202 kV, the peak intensity of the detected electric field at a distance of about 10 m from the center of the source was 7.2 kV/m. The corresponding peak power of the radiated electromagnetic field reached 76 MW, while the total radiated electromagnetic energy was about 0.65 J. The total energy efficiency of the resonant antenna was about 22% which can be improved by increasing the closing rapidity of the switch in the antenna.

  4. High-field superconducting nested coil magnet

    NASA Technical Reports Server (NTRS)

    Laverick, C.; Lobell, G. M.

    1970-01-01

    Superconducting magnet, employed in conjunction with five types of superconducting cables in a nested solenoid configuration, produces total, central magnetic field strengths approaching 70 kG. The multiple coils permit maximum information on cable characteristics to be gathered from one test.

  5. Enzyme Substrate Reactions in High Magnetic Fields

    PubMed Central

    Maling, J. E.; Weissbluth, M.; Jacobs, E. E.

    1965-01-01

    The reaction rates of two enzyme substrate systems, ribonuclease-RNA and succinate-cytochrome c reductase, were followed as a function of magnetic field from zero to 48,000 gauss. The reaction rates remained constant to within 10 per cent. PMID:5884011

  6. FIELD INVESTIGATION OF SULFITE FLUXES TO A DECIDUOUS FOREST

    EPA Science Inventory

    An intensive investigation of particulate sulfur fluxes to a deciduous forest was conducted at Oak Ridge, Tennessee, during May 1983. ddy correlation methods were used to measure fluxes of submicron particulate sulfur, of submicron particles in three different size ranges, and of...

  7. Integrating Field and Laboratory Investigations of Televised Violence and Aggression.

    ERIC Educational Resources Information Center

    Eron, Leonard D.; Huesmann, L. Rowell

    Longitudinal and intervention laboratory studies were conducted to investigate the effects of viewing televised violence on the aggressive behavior of elementary school children. In the longitudinal study 505 children were studied over a 3-year period. The measures used included peer nominated aggression, aggression anxiety and popularity,…

  8. A Field Course Investigation of a Pembrokeshire River.

    ERIC Educational Resources Information Center

    Bailey, R. G.

    1978-01-01

    The river was investigated at six stations from source to estuary. Modifications of water quality and aquatic communities are related to man's activities in the river basin. The organization of the exercise and the method employed are described. (Author/BB)

  9. ASTEROSEISMIC INVESTIGATION OF KNOWN PLANET HOSTS IN THE KEPLER FIELD

    SciTech Connect

    Christensen-Dalsgaard, J.; Kjeldsen, H.; Arentoft, T.; Frandsen, S.; Quirion, P.-O.; Brown, T. M.; Gilliland, R. L.; Borucki, W. J.; Koch, D.; Jenkins, J. M.

    2010-04-20

    In addition to its great potential for characterizing extra-solar planetary systems, the Kepler Mission is providing unique data on stellar oscillations. A key aspect of Kepler asteroseismology is the application to solar-like oscillations of main-sequence stars. As an example, we here consider an initial analysis of data for three stars in the Kepler field for which planetary transits were known from ground-based observations. For one of these, HAT-P-7, we obtain a detailed frequency spectrum and hence strong constraints on the stellar properties. The remaining two stars show definite evidence for solar-like oscillations, yielding a preliminary estimate of their mean densities.

  10. Spectral investigation of nonlinear local field effects in Ag nanoparticles

    SciTech Connect

    Sato, Rodrigo Takeda, Yoshihiko; Ohnuma, Masato; Oyoshi, Keiji

    2015-03-21

    The capability of Ag nanoparticles to modulate their optical resonance condition, by optical nonlinearity, without an external feedback system was experimentally demonstrated. These optical nonlinearities were studied in the vicinity of the localized surface plasmon resonance (LSPR), using femtosecond pump-and-probe spectroscopy with a white-light continuum probe. Transient transmission changes ΔT/T exhibited strong photon energy and particle size dependence and showed a complex and non-monotonic change with increasing pump light intensity. Peak position and change of sign redshift with increasing pump light intensity demonstrate the modulation of the LSPR. These features are discussed in terms of the intrinsic feedback via local field enhancement.

  11. GRACE gravity field modeling with an investigation on correlation between nuisance parameters and gravity field coefficients

    NASA Astrophysics Data System (ADS)

    Zhao, Qile; Guo, Jing; Hu, Zhigang; Shi, Chuang; Liu, Jingnan; Cai, Hua; Liu, Xianglin

    2011-05-01

    The GRACE (Gravity Recovery And Climate Experiment) monthly gravity models have been independently produced and published by several research institutions, such as Center for Space Research (CSR), GeoForschungsZentrum (GFZ), Jet Propulsion Laboratory (JPL), Centre National d’Etudes Spatiales (CNES) and Delft Institute of Earth Observation and Space Systems (DEOS). According to their processing standards, above institutions use the traditional variational approach except that the DEOS exploits the acceleration approach. The background force models employed are rather similar. The produced gravity field models generally agree with one another in the spatial pattern. However, there are some discrepancies in the gravity signal amplitude between solutions produced by different institutions. In particular, 10%-30% signal amplitude differences in some river basins can be observed. In this paper, we implemented a variant of the traditional variational approach and computed two sets of monthly gravity field solutions using the data from January 2005 to December 2006. The input data are K-band range-rates (KBRR) and kinematic orbits of GRACE satellites. The main difference in the production of our two types of models is how to deal with nuisance parameters. This type of parameters is necessary to absorb low-frequency errors in the data, which are mainly the aliasing and instrument errors. One way is to remove the nuisance parameters before estimating the geopotential coefficients, called NPARB approach in the paper. The other way is to estimate the nuisance parameters and geopotential coefficients simultaneously, called NPESS approach. These two types of solutions mainly differ in geopotential coefficients from degree 2 to 5. This can be explained by the fact that the nuisance parameters and the gravity field coefficients are highly correlated, particularly at low degrees. We compare these solutions with the official and published ones by means of spectral analysis. It is

  12. Echoes from the Field: An Ethnographic Investigation of Outdoor Science Field Trips

    ERIC Educational Resources Information Center

    Boxerman, Jonathan Zvi

    2013-01-01

    As popular as field trips are, one might think they have been well-studied. Nonetheless, field trips have not been heavily studied, and little research has mapped what actually transpires during field trips. Accordingly, to address this research gap, I asked two related research questions. The first question is a descriptive one: What happens on…

  13. Numerical investigation of high pressure and high Reynolds diffusion flame using Large Eddy Simulation

    NASA Astrophysics Data System (ADS)

    Nichkoohi, Ali Lohrasbi; Tousi, Abolghasem Mesgarpour

    2014-10-01

    Today, with nonstop improvement in computational power, Large-Eddy Simulation (LES) is a high demanding research tool for predicting engineering flows. Such flows on high pressure condition like diesel engines is extensively employed in ground and marine transportation, oblige the designer to control and predict toxic pollutants, while maintaining or improving their high thermal efficiency. This becomes one of the main challenging issues in decades. In the present work, numerical investigation of diffusion flame dynamics is performed in the near-field of high-Reynolds jet flow on high pressure condition encountered in diesel engine applications. This work discusses the implementation of Partially Stirred Reactor (PaSR) combustion model by the approaches of large eddy simulation (LES). The simulation results show that LES, in comparison with Reynolds-Averaged Navier-Stokes (RANS) simulation predicts and captures transient phenomena very well. These phenomena such as unsteadiness and curvature are inherent in the near-field of high Reynolds diffusion flame. The outcomes of this research are compared and validated by other researchers' results. Detailed comparisons of the statistics show good agreement with the corresponding experiments.

  14. Paramagnetic shimming for high-field MRI

    SciTech Connect

    Tomasi, D.; Tomasi, D.; Wang, R.L.

    2009-01-20

    The diamagnetism of biological tissues reduces the homogeneity of the magnetic field and may limit the number of samples in multi-sample gradient-recalled echo (GRE) experiments. This study aims to (1) evaluate the magnetic field distortions and signal loss artifacts in GRE images of proximal water samples, and (2) develop a passive shimming device to overcome this limitation. The magnetic field distribution produced by a diamagnetic H{sub 2}O sphere and a paramagnetic CuSO{sub 4} disk in a secondary phantom were mapped using GRE experiments and the phase reference method, and compared to the corresponding magnetostatics models. The water sphere produced a pronounced signal loss artifact in amplitude images. This artifact was significantly reduced when the paramagnetic disk was placed symmetrically between the water sphere and the secondary spherical phantom. The present study suggests that the use of paramagnetic shimming devices can help to minimize susceptibility-related MRI signal losses and to increase the number of samples in multi-sample MRI experiments. The volume susceptibility and the shape of paramagnetic shimming devices could be optimized for particular setups and samples accordingly.

  15. Investigation of the temperature field in a turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Byers, Clayton; Hultmark, Marcus

    2015-11-01

    The scaling and evolution of a developing turbulent thermal boundary layer is investigated. By allowing the temperature differences in the fluid to remain small enough to treat temperature as a passive scalar, the analysis can be extended to any turbulent convection/diffusion problem. Mean temperature scaling is developed and analyzed by utilizing the ``Asymptotic Invariance Principle'' developed by George and Castillo (1997). Possible effects of the Reynolds and Prandtl number are discussed. The derived power law solution for the inner and outer scaling is then used to develop a ``heat transfer law'' for the wall heat flux, qw. Data collection is performed with a newly developed MEMS sensor, allowing improved performance and reduced spatial and temporal filtering of the signal. Integration with a PIV system will allow direct measurements of the turbulent heat flux - θv to investigate the extent of the overlap layer and validity of the proposed scaling laws. Temperature variance 1/2 θ2 will also be investigated, with a possible scaling proposed.

  16. Complex Investigation of SBS Galaxies in Seven Selected Fields

    NASA Astrophysics Data System (ADS)

    Hakopian, Susanna

    2014-07-01

    It is known that the main criterion for the selection of active objects in the First Byurakan, otherwise Markarian survey was the presence of signs of UV-excess in their low-dispersion spectra. Using the presence of emission lines as the second criteria became real during the Second Byurakan survey because of its improved technique. Extended (not stellated) objects, selected with the use of this criterion, made the main part of the separate sample of SBS galaxies. Originally, this sample included 1286 objects, selected in 65 fields of the survey (16 square degree each), to which, with the help of other sources than the survey, there were later added some objects. We studied a subsample of SBS galaxies in seven selected fields (the deepest according to the V/Vmax criterion), including about the third of the whole sample. The first, already completed phase of this program was started with carrying out a follow-up slit spectroscopy of all, about 500 objects, based on observations with long-slit spectrographs with 6m telescope of SAO Russia and 2.6.m telescope of Byurakan. As a result redshifts were determined, as well as spectral classification was made for all of objects, using the scheme adapted to the spectral material. Besides other, obtained data allowed us to estimate the efficiency of used criteria for the selection of galaxies of different classes of starformation and nuclear activity along the full scale of the apparent magnitudes, including close to the limit values (18.5 < m pg < 19.5), etc. The fact that the total area of seven fields as the total number of objects in them comparable with these values for the survey as a whole, allows us to extrapolate the results to the whole sample of galaxies as an upper estimate. The second stage is to conduct detailed studies of individual galaxies in the first place, the most interesting in terms of morphology. They are based on panoramic spectroscopy obtained from observations at 6 m telescope of Russia and 2.6m

  17. Echoes from the Field: An Ethnographic Investigation of Outdoor Science Field Trips

    NASA Astrophysics Data System (ADS)

    Boxerman, Jonathan Zvi

    As popular as field trips are, one might think they have been well-studied. Nonetheless, field trips have not been heavily studied, and little research has mapped what actually transpires during field trips. Accordingly, to address this research gap, I asked two related research questions. The first question is a descriptive one: What happens on field trips? The second question is explanatory: What field trip events are memorable and why? I employed design research and ethnographic methodologies to study learning in naturally occurring contexts. I collaborated with middle-school science teachers to design and implement more than a dozen field trips. The field trips were nested in particular biology and earth sciences focal units. Students were tasked with making scientific observations in the field and then analyzing this data during classroom activities. Audio and video recording devices captured what happened during the field trips, classroom activities and discussions, and the interviews. I conducted comparative microanalysis of videotaped interactions. I observed dozens of events during the field trips that reverberated across time and place. I characterize the features of these events and the objects that drew interest. Then, I trace the residue across contexts. This study suggests that field trips could be more than one-off experiences and have the potential to be resources to seed and enrich learning and to augment interest in the practice of science.

  18. An X-ray Investigation of the NGC 346 Field in the SMC (2): The Field Population

    NASA Technical Reports Server (NTRS)

    Naze, Y.; Hartwell, J. M.; Stevens, I. R.; Manfroid, J.; Marchenko, S.; Corcoran, M. F.; Moffat, A. F. J.; Skalkowski, G.

    2003-01-01

    We present results from a Chandra observation of the NGC 346 cluster, which is the ionizing source of N66, the most luminous HII region and the largest star formation region in the SMC. In the first part of this investigation, we have analysed the X-ray properties of the cluster itself and the remarkable star HD 5980. But the field contains additional objects of interest. In total, 79 X-ray point sources were detected in the Chandra observation: this is more than five times the number of sources detected by previous X-ray surveys. We investigate here their characteristics in detail. The sources possess rather high hardness ratios, and their cumulative luminosity function is steeper than that for the rest of the SMC at higher .luminosities. Their absorption columns suggest that most of the sources belong to NGC346. Using new UBV RI imaging with the ESO 2.2m telescope, we also discovered possible counterparts for 36 of these X-ray sources and estimated a B spectral type for a large number of these counterparts. This tends to suggest that most of the X-ray sources in the field are in fact X-ray binaries. Finally, some objects show X-ray and/or optical variability, with a need for further monitoring.

  19. Investigation of Hot Carrier Degradation in Shallow-Trench-Isolation-Based High-Voltage Laterally Diffused Metal-Oxide-Semiconductor Field-Effect Transistors by a Novel Direct Current Current-Voltage Technique

    NASA Astrophysics Data System (ADS)

    He, Yandong; Zhang, Ganggang

    2012-04-01

    Shallow trench isolation (STI) based laterally diffused metal-oxide-semiconductor (LDMOS) devices have become popular with its better tradeoff between breakdown voltage and on-resistance and its compatibility with the standard complementary metal-oxide-semiconductor (CMOS) process. A novel direct current current-voltage (DCIV) technique demonstrated with multiple sharp peak signals is proposed to characterize interface state generation in the channel and in the STI drift regions separately. Degradation of STI-based LDMOS transistors in various hot-carrier stress modes is investigated experimentally by proposed technique. A two-dimensional numerical device simulation is performed to obtain insight into the proposed technique and device degradation characteristics under hot-carrier stress conditions. The impact of interface state location on device electrical characteristics is analyzed from measurement and simulation. Our results show that the maximum Isub stress becomes the worst hot-carrier degradation mode in term of the on-resistance degradation, which is attributed to interface state generation under STI drift region.

  20. Results of investigation at the Ahuachapan Geothermal Field, El Salvador

    SciTech Connect

    Fink, J.B. )

    1990-04-01

    The Ahuachapan Geothermal Field (AGF) is a 95 megawatt geothemal-sourced power-plant operated by the Comision Ejecutiva Hidroelectrica del Rio Lempa (CEL) of El Salvador. During the past decade, as part of an effort to increase in situ thermal reserves in order to realize the full generation capacity of the AGF, extensive surface geophysical coverage has been obtained over the AGF and the prospective Chipilapa area to the east. The geophysical surveys were performed to determine physical property characteristics of the known reservoir and then to search for similar characteristics in the Chipilapa area. A secondary objective was to evaluate the surface recharge area in the highlands to the south of the AGF. The principal surface electrical geophysical methods used during this period were DC resistivity and magnetotellurics. Three available data sets have been reinterpreted using drillhole control to help form geophysical models of the area. The geophysical models are compared with the geologic interpretations.

  1. First Investigation on the Radiation Field of the Spherical Hohlraum

    NASA Astrophysics Data System (ADS)

    Huo, Wen Yi; Li, Zhichao; Chen, Yao-Hua; Xie, Xuefei; Lan, Ke; Liu, Jie; Ren, Guoli; Li, Yongsheng; Liu, Yonggang; Jiang, Xiaohua; Yang, Dong; Li, Sanwei; Guo, Liang; Zhang, Huan; Hou, Lifei; Du, Huabing; Peng, Xiaoshi; Xu, Tao; Li, Chaoguang; Zhan, Xiayu; Yuan, Guanghui; Zhang, Haijun; Jiang, Baibin; Huang, Lizhen; Du, Kai; Zhao, Runchang; Li, Ping; Wang, Wei; Su, Jingqin; Ding, Yongkun; He, Xian-Tu; Zhang, Weiyan

    2016-07-01

    The first spherical hohlraum energetics experiment is accomplished on the SGIII-prototype laser facility. In the experiment, the radiation temperature is measured by using an array of flat-response x-ray detectors (FXRDs) through a laser entrance hole at four different angles. The radiation temperature and M -band fraction inside the hohlraum are determined by the shock wave technique. The experimental observations indicate that the radiation temperatures measured by the FXRDs depend on the observation angles and are related to the view field. According to the experimental results, the conversion efficiency of the vacuum spherical hohlraum is in the range from 60% to 80%. Although this conversion efficiency is less than the conversion efficiency of the near vacuum hohlraum on the National Ignition Facility, it is consistent with that of the cylindrical hohlraums used on the NOVA and the SGIII-prototype at the same energy scale.

  2. Simulation of radiolysis in the near field of a nuclear repository and the spectrophotometric investigation of the formation of radiolysis by-products by applying high energy beam-like experiments

    SciTech Connect

    Hartmann, T.; Paviet-Hartmann, P.; Wetteland, C. J.; Lu, N.; Ware, S. D.; Sage, S.

    2002-01-01

    In the event of inundation of a nuclear waste repository located in a geological salt formation, chloride brines in contact with nuclear waste will be exposed to different kind of radiation depending on waste-form conditions. Ionizing radiations, however, have the ability to significantly affect the groundwater chemistry of the brines through the formation of free radicals, ionic- and molecular species; among them the typical byproducts of a-radiolysis: hypochlorite (OC1-) and hypochlorous acid (HOCl). In the absence of effects which arc supposed to dominate the redox conditions in the repository (corrosion of metals, microbial activity) the presence of OC1- is known to increase the redox potential of the brines and further to influence the stability of actinide waste-forms by accelerating their dissolution arid - most importantly - to oxidize actinides to their higlier oxidation states, whicli are gcncrally the most soluble ones. We are presenting a new approach to determine the radiation-induced formation rates of hypochlorite and hypochlorous acid as a first step to assess long-term steady-state repository conditions. To ovt:rcome the serious constraints of conventional radiocheinical work with GBq activity levels, we are simulating a-irradiation of chloride brines by the adaptation of ion-beam-line experiments. Therefore, we irradiate liquid chloride brine targets with 5 MeV protons, and 5 MeV helium ions. The irradiation-induced formation rates of OCX- and HOC1 were determined by UV-Vis spectrophotometry. To give an example, the measured G values for the HOCl formation in 3.7 M MgC12.6H20, pW 4.42, irradiated by 5 MeV protons was determined to be 0.0374 {+-} 0.0022, and 0.0536 {+-} 49 by irradiating with 5 MeV helium. The distinguished ltnowledge about the radiation-induced production of oxo-chloride species is the first step towards the assumption of their steady-state concentrations in the irradiation field of the repository.

  3. Field investigation of FGD system chemistry. Final report

    SciTech Connect

    Litherland, S.T.; Colley, J.D.; Glover, R.L.; Maller, G.; Behrens, G.P.

    1984-12-01

    Three full-scale wet limestone FGD systems were investigated to gain a better understanding of FGD system operation and chemistry. The three plants which participated in the program were South Mississippi Electric Power Association's R. D. Morrow Station, Colorado-Ute Electric Association's Craig Station, and Central Illinois Light Company's Duck Creek Station. Each FGD system was characterized with respect to SO/sub 2/ removal, liquid and solid phase chemistry, and calcium sulfite and calcium sulfate relative saturation. Mist eliminator chemistry and performance were documented at Morrow and Duck Creek. Solutions to severe mist eliminator scaling and pluggage were demonstrated at Duck Creek. A technical and econ

  4. Final Report: Experimental Investigation of Nonlinear Plasma Wake-Fields

    SciTech Connect

    Rosenzweig, J.

    1997-10-31

    We discuss the exploration of the newly proposed blowout regime of the plasma wakefield accelerator and advanced photoinjector technology for linear collider applications. The plasma wakefield experiment at ANL produced several ground-breaking results in the physics of the blowout regime. The photoinjector R and D effort produced breakthroughs in theoretical, computational, and experimental methods in high brightness beam physics. Results have been published.

  5. Enhanced Field Emission Studies on Niobium Surfaces Relevant to High Field Superconducting Radio-Frequency Devices

    SciTech Connect

    Tong Wang

    2002-09-18

    Enhanced field emission (EFE) presents the main impediment to higher acceleration gradients in superconducting niobium (Nb) radiofrequency cavities for particle accelerators. The strength, number and sources of EFE sites strongly depend on surface preparation and handling. The main objective of this thesis project is to systematically investigate the sources of EFE from Nb, to evaluate the best available surface preparation techniques with respect to resulting field emission, and to establish an optimized process to minimize or eliminate EFE. To achieve these goals, a scanning field emission microscope (SFEM) was designed and built as an extension to an existing commercial scanning electron microscope (SEM). In the SFEM chamber of ultra high vacuum, a sample is moved laterally in a raster pattern under a high voltage anode tip for EFE detection and localization. The sample is then transferred under vacuum to the SEM chamber equipped with an energy-dispersive x-ray spectrometer for individual emitting site characterization. Compared to other systems built for similar purposes, this apparatus has low cost and maintenance, high operational flexibility, considerably bigger scan area, as well as reliable performance. EFE sources from planar Nb have been studied after various surface preparation, including chemical etching and electropolishing, combined with ultrasonic or high-pressure water rinse. Emitters have been identified, analyzed and the preparation process has been examined and improved based on EFE results. As a result, field-emission-free or near field-emission-free surfaces at ~140 MV/m have been consistently achieved with the above techniques. Characterization on the remaining emitters leads to the conclusion that no evidence of intrinsic emitters, i.e., no fundamental electric field limit induced by EFE, has been observed up to ~140 MV/m. Chemically etched and electropolished Nb are compared and no significant difference is observed up to ~140 MV/m. To

  6. Pulsed magnetic field measurement system based on colossal magnetoresistance-B-scalar sensors for railgun investigation.

    PubMed

    Stankevič, T; Medišauskas, L; Stankevič, V; Balevičius, S; Żurauskienė, N; Liebfried, O; Schneider, M

    2014-04-01

    A high pulsed magnetic field measurement system based on the use of CMR-B-scalar sensors was developed for the investigations of the electrodynamic processes in electromagnetic launchers. The system consists of four independent modules (channels) which are controlled by a personal computer. Each channel is equipped with a CMR-B-scalar sensor connected to the measurement device-B-scalar meter. The system is able to measure the magnitude of pulsed magnetic fields from 0.3 T to 20 T in the range from DC up to 20 kHz independently of the magnetic field direction. The measurement equipment circuit is electrically separated from the ground and shielded against low and high frequency electromagnetic noise. The B-scalar meters can be operated in the presence of ambient pulsed magnetic fields with amplitudes up to 0.2 T and frequencies higher than 1 kHz. The recorded signals can be transmitted to a personal computer in a distance of 25 m by means of a fiber optic link. The system was tested using the electromagnetic railgun RAFIRA installed at the French-German Research Institute of Saint-Louis, France. PMID:24784635

  7. Experimental Investigation of Porous-floor Effects on Cavity Flow Fields at Supersonic Speeds

    NASA Technical Reports Server (NTRS)

    Wilcox, Floyd J., Jr.

    1990-01-01

    An experimental investigation was conducted to determine the effectiveness of a passive-venting system to modify the flow field characteristics of a rectangular-box cavity at supersonic speeds. The passive-venting system consists of a porous floor with a vent chamber beneath the floor. For certain cavity length-to-height ratios, this configuration allowed high-pressure air at the rear of the cavity to vent to the forward part of the cavity, thereby modifying the cavity flow field. The wind-tunnel model consisted of a flat plate that housed a cavity mounted on a balance such that only the cavity drag was measured. The cavity height remained constant, and the length varied with rectangular-block inserts. Both solid-and porous-floor cavities were tested for comparison at Mach numbers of 1.60, 1.90, 2.16, and 2.86. These results showed that the passive-venting system did modify the cavity flow field. In order to determine the type flow field which existed for the porous-floor configuration, pressures were measured inside the cavity at the same conditions and for the same configurations as those used in the drag tests. Pressure data were also obtained with stores mounted in the cavity. These results, along with Schlieren photographs and the tabulated data, are presented to document the porous-floor cavity flow field.

  8. Results of investigations at the Zunil geothermal field, Guatemala: Well logging and brine geochemistry

    SciTech Connect

    Adams, A.; Dennis, B.; Van Eeckhout, E.; Goff, F.; Lawton, R.; Trujillo, P.E.; Counce, D.; Archuleta, J. ); Medina, V. . Unidad de Desarollo Geotermico)

    1991-07-01

    The well logging team from Los Alamos and its counterpart from Central America were tasked to investigate the condition of four producing geothermal wells in the Zunil Geothermal Field. The information obtained would be used to help evaluate the Zunil geothermal reservoir in terms of possible additional drilling and future power plant design. The field activities focused on downhole measurements in four production wells (ZCQ-3, ZCQ-4, ZCQ-5, and ZCQ-6). The teams took measurements of the wells in both static (shut-in) and flowing conditions, using the high-temperature well logging tools developed at Los Alamos National Laboratory. Two well logging missions were conducted in the Zunil field. In October 1988 measurements were made in well ZCQ-3, ZCQ-5, and ZCQ-6. In December 1989 the second field operation logged ZCQ-4 and repeated logs in ZCQ-3. Both field operations included not only well logging but the collecting of numerous fluid samples from both thermal and nonthermal waters. 18 refs., 22 figs., 7 tabs.

  9. Development of Point Doppler Velocimetry for Flow Field Investigations

    NASA Technical Reports Server (NTRS)

    Cavone, Angelo A.; Meyers, James F.; Lee, Joseph W.

    2006-01-01

    A Point Doppler Velocimeter (pDv) has been developed using a vapor-limited iodine cell as the sensing medium. The iodine cell is utilized to directly measure the Doppler shift frequency of laser light scattered from submicron particles suspended within a fluid flow. The measured Doppler shift can then be used to compute the velocity of the particles, and hence the fluid. Since this approach does not require resolution of scattered light from individual particles, the potential exists to obtain temporally continuous signals that could be uniformly sampled in the manner as a hot wire anemometer. This leads to the possibility of obtaining flow turbulence power spectra without the limitations of fringe-type laser velocimetry. The development program consisted of a methodical investigation of the technology coupled with the solution of practical engineering problems to produce a usable measurement system. The paper outlines this development along with the evaluation of the resulting system as compared to primary standards and other measurement technologies.

  10. Field investigation of airborne radioactivity anomalies in Marquette County, Michigan

    USGS Publications Warehouse

    James, Harold L.

    1950-01-01

    The broad radioactivity anomalies recorded by the airborne detector in the vicinity of Republic, Marquette County, Michigan, coincide rather closely with parts of a granitic complex chiefly of Archean age. Ground examination of the rock in these areas of high radioactivity shows that the granitic rock typically yields two to four times the normal background activity. Fissures, shear zones, veins, and pegmatites were tested carefully. None exhibited activity higher than that of the adjacent granitic rock. It is significant that the zones of more-than-average radio-activity are related to the larger elements of the geology - in fact, the information will be of considerable value in reconsideration of some of the regional problems.

  11. Investigation of the plastic fracture of high strength steels

    NASA Technical Reports Server (NTRS)

    Cox, T. B.; Low, J. R., Jr.

    1972-01-01

    This investigation deals in detail with the three recognized stages of plastic fracture in high strength steels, namely, void initiation, void growth, and void coalescence. The particular steels under investigation include plates from both commercial purity and high purity heats of AISI 4340 and 18 Ni, 200 grade maraging steels. A scanning electron microscope equipped with an X-ray energy dispersive analyzer, together with observations made using light microscopy, revealed methods of improving the resistance of high strength steels to plastic fracture.

  12. Limited field investigation report for the 100-DR-1 Operable Unit

    SciTech Connect

    Not Available

    1994-06-01

    This limited field investigation (LFI) report summarizes the data collection and analysis activities conducted during the 100-DR-1 Source Operable Unite LFI and the associated qualitative risk assessment (QRA), and makes recommendations on the continued candidacy of high-priority sites for interim remedial measures (IRM). The results and recommendations presented in this report are generally independent of future land use scenarios. The 100-DR-1 Operable Unit is one of four operable units associated with the 100 D/DR Area at the Hanford Site. The 100-DR-1 Operable Unit encompasses approximately 1.5 km{sup 2} (0.59 mi{sup 2}) and is located immediately adjacent to the Columbia River shoreline. In general, it contains waste facilities associated with the original plant facilities constructed to support D Reactor facilities, as well as cooling water retention basin systems for both D and DR Reactors. The 100-DR-1 LFI began the investigative phase of the remedial investigation for a select number of high-priority sites. The LFI was performed to provide additional data needed to support selection, design and implementation of IRM, if needed. The LFI included data compilation, nonintrusive investigations, intrusive investigations, summarization of 100 Area aggregate studies, and data evaluation.

  13. Double disordered YBCO coated conductors of industrial scale: high currents in high magnetic field

    NASA Astrophysics Data System (ADS)

    Abraimov, D.; Ballarino, A.; Barth, C.; Bottura, L.; Dietrich, R.; Francis, A.; Jaroszynski, J.; Majkic, G. S.; McCallister, J.; Polyanskii, A.; Rossi, L.; Rutt, A.; Santos, M.; Schlenga, K.; Selvamanickam, V.; Senatore, C.; Usoskin, A.; Viouchkov, Y. L.

    2015-11-01

    A significant increase of critical current in high magnetic field, up to 31 T, was recorded in long tapes manufactured by employing a double-disorder route. In a double-disordered high-temperature superconductor (HTS), a superimposing of intrinsic and extrinsic disorder takes place in a way that (i) the intrinsic disorder is caused by local stoichiometry deviations that lead to defects of crystallinity that serve as pining centers in the YBa2Cu3O x-δ matrix and (ii) the extrinsic disorder is introduced via embedded atoms or particles of foreign material (e.g. barium zirconate), which create a set of lattice defects. We analyzed possible technological reasons for this current gain. The properties of these tapes over a wider field-temperature range as well as field anisotropy were also studied. Record values of critical current as high as 309 A at 31 T, 500 A at 18 Tm and 1200 A at 5 T were found in 4 mm wide tape at 4.2 K and B perpendicular to tape surface. HTS layers were processed in medium-scale equipment that allows a maximum batch length of 250 m while 22 m long batches were provided for investigation. Abnormally high ratios (up to 10) of critical current density measured at 4.2 K, 19 T to critical current density measured at 77 K, self-field were observed in tapes with the highest in-field critical current. Anisotropy of the critical current as well as angular dependences of n and α values were investigated. The temperature dependence of critical current is presented for temperatures between 4.2 and 40 K. Prospects for the suppression of the dog-bone effect by Cu plating and upscale of processing chain to >500 m piece length are discussed.

  14. Field Investigation Plan for 1301-N and 1325-N FacilitiesSampling to Support Remedial Design

    SciTech Connect

    S. G. Weiss.

    1998-12-04

    This field investigation plan (FIP) provides for the sampling and analysis activities supporting the remedial design planning for the planned removal action for the 1301-N and 1325-N Liquid Waste Disposal Facilities (LWDFs), which are treatment, storage,and disposal (TSD) units (cribs/trenches). The planned removalaction involves excavation, transportation, and disposal of contaminated material at the Environmental Restoration Disposal Facility (ERDF).An engineering study (BHI 1997) was performed to develop and evaluate various options that are predominately influenced by the volume of high- and low-activity contaminated soil requiring removal. The study recommended that additional sampling be performed to supplement historical data for use in the remedial design.

  15. Initial Results from the Vector Electric Field Investigation on the C/NOFS Satellite

    NASA Technical Reports Server (NTRS)

    Pfaff, R.; Rowland, D.; Acuna, M.; Le, G.; Farrell, W.; Holzworth, R.; Wilson, G.; Burke, W.; Freudenreich, H.; Bromund, K.; Liebrecht, C.; Martin, S.; Kujawski, J.; Uribe, P.; Fourre, R.; McCarthy, M.; Maynard, N.; Berthelier, J.-J.; Steigies, C.

    2009-01-01

    Initial results are presented from the Vector Electric Field Investigation (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregularities. The VEFI instrument includes a vector DC electric field detector, a fixed-bias Langmuir probe operating in the ion saturation regime, a flux gate magnetometer, an optical lightning detector, and associated electronics including a burst memory. The DC electric field detector has revealed zonal and meridional electric fields that undergo a diurnal variation, typically displaying eastward and outward-directed fields during the day and westward and downward-directed fields at night. In general, the measured DC electric field amplitudes are in the 0.5-2 mV/m range, corresponding to I3 x B drifts of the order of 30-150 m/s. What is surprising is the high degree of large-scale (10's to 100's of km) structure in the DC electric field, particularly at night, regardless of whether well-defined spread-F plasma density depletions are present. The spread-F density depletions and corresponding electric fields that have been detected thus far have displayed a preponderance to appear between midnight and dawn. Associated with the narrow plasma depletions that are detected are broad spectra of electric field and plasma density irregularities for which a full vector set of measurements is available for detailed study. On some occasions, localized regions of low frequency (< 8 Hz) magnetic field broadband irregularities have been detected, suggestive of filamentary currents, although there is no one-to-one correspondence of these waves with the observed plasma density depletions, at least within the data examined thus far. Finally, the data set includes a wide range of ELF/VLF/HF waves corresponding to a variety of plasma waves, in particular banded ELF hiss, whistlers, and lower hybrid wave turbulence

  16. A Global Probe of Cosmic Magnetic Fields to High Redshifts

    NASA Astrophysics Data System (ADS)

    Kronberg, P. P.; Bernet, M. L.; Miniati, F.; Lilly, S. J.; Short, M. B.; Higdon, D. M.

    2008-03-01

    Faraday rotation (rotation measure [RM]) probes of magnetic fields in the universe are sensitive to cosmological and evolutionary effects as z increases beyond ~1 because of the scalings of electron density and magnetic fields, and the growth in the number of expected intersections with galaxy-scale intervenors, dN/dz. In this new global analysis of an unprecedented large sample of RMs of high-latitude quasars extending out to z ~ 3.7, we find that the distribution of RM broadens with redshift in the 20-80 rad m-2 range, despite the (1 + z)-2 wavelength dilution expected in the observed Faraday rotation. Our results indicate that the universe becomes increasingly "Faraday-opaque" to sources beyond z ~ 2; that is, as z increases, progressively fewer sources are found with a "small" RM in the observer's frame. This is in contrast to sources at zlesssim 1. They suggest that the environments of galaxies were significantly magnetized at high redshifts, with magnetic field strengths that were at least as strong within a few Gyr of the big bang as at the current epoch. We separately investigate a simple unevolving toy model in which the RM is produced by Mg II absorber systems, and find that it can approximately reproduce the observed trend with redshift. An additional possibility is that the intrinsic RM associated with the radio sources was much higher in the past, and we show that this is not a trivial consequence of the higher radio luminosities of the high-redshift sources.

  17. Investigating the impact of electromagnetic fields on human cells: A thermodynamic perspective

    NASA Astrophysics Data System (ADS)

    Lucia, Umberto; Ponzetto, Antonio; Deisboeck, Thomas S.

    2016-02-01

    The consequences of the interactions of electromagnetic waves, as used in conventional MRI technology, with human cells are not fully understood. To analyze these interactions, a novel thermodynamic approach is presented that is based on the relationship between electromagnetic and thermodynamic quantities. The theoretical results indicate that the waves' impact is largest at high magnetic field strengths and at low frequencies. This is the first step towards a clinically useful framework to quantitatively assess MRI impact including a potential trade-off between the desired increase in spatial resolution that higher magnetic field strengths yield for diagnostic purposes and the danger this may pose for cell membranes, and by extension, for the tissues investigated.

  18. Qualitative investigation of cryogenic fluid injection into a supersonic flow field

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Boldman, D. R.; Neumann, H. E.; Vlcek, B. L.

    1990-01-01

    The behavior of liquid nitrogen injected into a supersonic nitrogen flow field was investigated using an experimental apparatus in which a Mach 2.7 2D gas nitrogen tunnel is coupled with a high-pressure cryogenic source. Observations were monitored and recorded via a video camera and a motion picture camera. It was found that the penetration of a supersonic flow field by injection of liquid nitrogen is strongly dependent on the flow Mach number, the cryogen injection pressure (Pi/Pc), the injector configuration, and the cryogen temperature. For a 2D gaseous N2, Mach 2.7 tunnel, with cryogen injection Pi/Pc approaching 2, the injected fluid penetration for the 1/8-in. injection port approached one half of the tunnel width at 90-deg injection, and one fourth of the tunnel width at 20-deg injection.

  19. Countering Solutal Buoyant Convection with High Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Ramachandran, N.; Leslie, F. W.

    2002-01-01

    An important component in biotechnology, particularly in the area of protein engineering and rational drug design is the knowledge of the precise three-dimensional molecular structure of proteins. The quality of structural information obtained from X-ray diffraction methods is directly dependent on the degree of perfection of the protein crystals. As a consequence, the growth of high quality macromolecular crystals for diffraction analyses has been the central focus for biochemist, biologists, and bioengineers. Macromolecular crystals are obtained from solutions that contain the crystallizing species in equilibrium with higher aggregates, ions, precipitant, other possible phases of the protein, foreign particles, the walls of the container, and a likely host of other impurities. By changing transport modes in general, i.e., reduction of convection and sedimentation, as is achieved in microgravity, we have been able to dramatically effect the movement and distribution of macromolecules in the fluid, and thus their transport, formation of crystal nuclei, and adsorption to the crystal surface. While a limited number of high quality crystals from space flights have been obtained, as the recent National Research Council (NRC) review of the NASA microgravity crystallization program pointed out, the scientific approach and research in crystallization of proteins has been mainly empirical yielding inconclusive results. We postulate that we can reduce convection in ground-based experiments and we can understand the different aspects of convection control through the use of strong magnetic fields and field gradients. We postulate that limited convection in a magnetic field will provide the environment for the growth of high quality crystals. The approach exploits the variation of fluid magnetic susceptibility with concentration for this purpose and the convective damping is realized by appropriately positioning the crystal growth cell so that the magnetic susceptibility

  20. A high brightness field emission display

    SciTech Connect

    Palevsky, A.

    1996-12-31

    The military requirement for avionics display performance requires that displays be legible with 10,000 foot-candles (fc) bright light shining into the pilot`s eyes, or 10,000 fc shining directly on the display. The contrast ratio under these conditions must be at least 4.66:1. In addition, instant-on operation is sought for temperatures as low as {minus}54 C. Currently these specifications can barely be met by monochrome CRTs whose use is counter-indicated by other factors. No color display can achieve optimum performance in the areas mentioned, nor do any current contenders, primarily AMLCD`s, have any prospects of achieving full compliance. The FED being developed by Raytheon shows strong promise of being able to achieve the brightness and contrast ratios desired. The FED is also inherently able to provide instant-on functionality at any terrestrial temperature and does not require any heating at low temperatures. The technical objective of the Raytheon development program is to develop a high performance, full color, FED Panel that meets the performance and environmental operating condition requirements specified for military and other high performance display applications.

  1. High magnetic fields at the Clarendon Laboratory, Oxford

    NASA Astrophysics Data System (ADS)

    Hudson, P. A.; Jones, H.; Whitworth, H. M.

    The Clarendon Laboratory in Oxford has been a centre for research in high magnetic fields for a number of years. The high-field facilities have been established around a 2MW do motorgenerator and today include a number of IOT solenoids which are energised by this machine as well as a hybrid resistive/superconductive magnet which is operated as an item of established laboratory equipment in which fields of 16T are routinely produced.

  2. Investigation of High School Students' Reading Compherension Levels According to Various Variables

    ERIC Educational Resources Information Center

    Ceran, Dilek

    2015-01-01

    The purpose of this study is to investigate the level of reading comprehension of high school students in their fields of study and learning strategies to explain the relationship between the level of reading comprehension. This working group is composed of 11th grade high school students. In this study, relational model was used. In the study…

  3. Investigation of the three-dimensional flow field within a transonic fan rotor: experiment and analysis

    SciTech Connect

    Pierzga, M.J.; Wood, J.R.

    1984-01-01

    An experimental investigation of the three-dimensional flow field through a low aspect ratio, transonic, axial-flow fan rotor has been conducted using an advanced laser anemometer (LA) system. Laser velocimeter measurements of the rotor flow field at the design operating speed and over a range of through-flow conditions are compared to analytical solutions. The numerical technique used yields the solution to the full, three-dimensional, unsteady Euler equations using an explicit time-marching, finite volume approach. The numerical analysis, when coupled with a simplified boundary layer calculation, generally yields good agreement with the experimental data. The test rotor has an aspect ratio of 1.56, a design total pressure ratio of 1.629 and a tip relative Mach number of 1.38. The high spatial resolution of the LA data matrix (9 radial by 30 axial by 50 blade-to-blade) permits details of the transonic flow field such as shock location, turning distribution and blade loading levels to be investigated and compared to analytical results.

  4. Electron probe microanalysis for high pressure minerals investigation

    NASA Astrophysics Data System (ADS)

    Lavrentiev, Y. G.; Sobolev, N. V.; Korolyuk, V. N.; Usova, L. V.

    2007-12-01

    In the early 1968 in Siberian Branch of the Academy of Sciences of USSR, Novosibirsk, electron probe microanalyzer MS-46 was installed and started to operate for high pressure minerals EPMA investigation. In collaboration with Geophysical Laboratory of Carnegie Institution (Drs. F.R. Boyd, F. Schairer) a set of standards for silicates analysis was developed. Technique for quantitative analysis was developed (Lavrentiev et al., 1974, Zavodsk. Lab., v. 40, p. 657-661) and applied for the first in the USSR analyses of pyropes, associated with Siberian diamonds both as inclusions and xenoliths of diamondiferous peridotites (Sobolev et al., 1969, Dokl. Akad. Nauk SSSR, v. 188, p. 1141-1143; v. 189, p. 162-165). As a result of that research, unique Cr-rich subcalcic pyropes with high knorringite content were found in diamond-bearing kimberlites only and new mineralogical criteria for diamond exploration were developed (Sobolev 1971, Geol. Geofiz., v. 12, p. 70-80) which are still in use worldwide. Further development of electron probe instruments (JXA-5A, Camebax Micro, JXA-8100) and computers, as well as development of analysis technique led to creation of large analytical database. In another field of EPMA - determination of small concentrations of elements - for the first time importance of 0.01-0.3% Na2O admixtures in garnets (Sobolev, Lavrentiev, 1971, Contrib. Min. Petr., v. 31, p. 1-12) and K2O in clinopyroxenes (Sobolev et al., 1970, Dokl. Akad. Nauk SSSR, v. 192, p. 1349-1352) were demonstrated. Since then, determination of sodium content in EPMA of garnets and potassium in pyroxenes became a routine technique. Last generation analyzer (JXA-8100) provided record results down to 6 ppm in detection limit of Ni in pyropes (Lavrentiev et al., Rus. Geol. Geophys., 2006, v. 47, p. 1090-1093). As a result, application of EPMA for single mineral geothermometry (currently based mainly on PIXE method) becomes possible.

  5. Topical Developments in High-Field Dynamic Nuclear Polarization

    PubMed Central

    Kiesewetter, Matthew K.; Frantz, Derik K.; Walish, Joseph J.; Ravera, Enrico; Luchinat, Claudio; Swager, Timothy M.; Griffin, Robert G.

    2015-01-01

    We report our recent efforts directed at improving high-field DNP experiments. We investigated a series of thiourea nitroxide radicals and the associated DNP enhancements ranging from ε = 25 to 82 that demonstrate the impact of molecular structure on performance. We directly polarized low-gamma nuclei including 13C, 2H, and 17O using trityl via the cross effect. We discuss a variety of sample preparation techniques for DNP with emphasis on the benefit of methods that do not use a glass-forming cryoprotecting matrix. Lastly, we describe a corrugated waveguide for use in a 700 MHz / 460 GHz DNP system that improves microwave delivery and increases enhancements up to 50%. PMID:25977588

  6. Large scale magnetic fields in galaxies at high redshifts

    NASA Astrophysics Data System (ADS)

    Bernet, M. L.; Miniati, F.; Lilly, S. J.; Kronberg, P. P.; Dessauges-Zavadsky, M.

    2012-09-01

    In a recent study we have used a large sample of extragalactic radio sources to investigate the redshift evolution of the Rotation Measure (RM) of polarized quasars up to z ≈ 3.0. We found that the dispersion in the RM distribution of quasars increases at higher redshifts and hypothesized that MgII intervening systems were responsible for the observed trend. To test this hypothesis, we have recently obtained high-resolution UVES/VLT spectra for 76 quasars in our sample and in the redshift range 0.6 < z < 2.0. We found a clear correlation between the presence of strong MgII systems and large RMs. This implies that normal galaxies at z ≈ 1 already had large-scale magnetic fields comparable to those seen today.

  7. Exploration of Traveling Waves in High Field Magnetic Resonance Imaging

    NASA Astrophysics Data System (ADS)

    Hernandez, Zachary

    2010-10-01

    MRI has been a remarkable means of medical imaging for the last three decades without exposure to ionizing radiation. The increase in MRI signal with the increase of magnetic field strength is the main motive in a move towards imaging at higher field strengths. However, the advent of higher field strength MRI has come with the challenge of maintaining homogeneous excitation fields (B1). One promising solution to this has been to transmit radio-frequency (RF) signals using a patch antenna instead of the usual RF coil. This technique exploits the theory of waveguides and traveling waves typically used in high frequency applications. In this particular study we have investigated this unique application by measuring B1 maps, geometric distortions, and signal-to-noise ratios (SNRs) in order to better quantify its potential in MRI. Using phantoms to match the similar physical features of the human head/torso region, we ran comparative scans using the traveling wave setup versus the conventional head volume coil setup on a Philips 7 Tesla MRI scanner. The goal of this experiment was to systematically measure B1 maps for flip angle efficiency and multi-planar rendering images for geometric distortion. Although the application of traveling wave in MRI does suffer from low excitation (small flip angles), there seems to be little to no correlation between traveling wave phase variability and frequency/phase encoding. Therefore, further experiments, if carried out, may enhance image quality such as RF shielding, the use of local receive coils, and/or the addition of a second patch antenna.

  8. Sessile multidroplets and salt droplets under high tangential electric fields

    PubMed Central

    Xie, Guoxin; He, Feng; Liu, Xiang; Si, Lina; Guo, Dan

    2016-01-01

    Understanding the interaction behaviors between sessile droplets under imposed high voltages is very important in many practical situations, e.g., microfluidic devices and the degradation/aging problems of outdoor high-power applications. In the present work, the droplet coalescence, the discharge activity and the surface thermal distribution response between sessile multidroplets and chloride salt droplets under high tangential electric fields have been investigated with infrared thermography, high-speed photography and pulse current measurement. Obvious polarity effects on the discharge path direction and the temperature change in the droplets in the initial stage after discharge initiation were observed due to the anodic dissolution of metal ions from the electrode. In the case of sessile aligned multidroplets, the discharge path direction could affect the location of initial droplet coalescence. The smaller unmerged droplet would be drained into the merged large droplet as a result from the pressure difference inside the droplets rather than the asymmetric temperature change due to discharge. The discharge inception voltages and the temperature variations for two salt droplets closely correlated with the ionization degree of the salt, as well as the interfacial electrochemical reactions near the electrodes. Mechanisms of these observed phenomena were discussed. PMID:27121926

  9. Sessile multidroplets and salt droplets under high tangential electric fields.

    PubMed

    Xie, Guoxin; He, Feng; Liu, Xiang; Si, Lina; Guo, Dan

    2016-01-01

    Understanding the interaction behaviors between sessile droplets under imposed high voltages is very important in many practical situations, e.g., microfluidic devices and the degradation/aging problems of outdoor high-power applications. In the present work, the droplet coalescence, the discharge activity and the surface thermal distribution response between sessile multidroplets and chloride salt droplets under high tangential electric fields have been investigated with infrared thermography, high-speed photography and pulse current measurement. Obvious polarity effects on the discharge path direction and the temperature change in the droplets in the initial stage after discharge initiation were observed due to the anodic dissolution of metal ions from the electrode. In the case of sessile aligned multidroplets, the discharge path direction could affect the location of initial droplet coalescence. The smaller unmerged droplet would be drained into the merged large droplet as a result from the pressure difference inside the droplets rather than the asymmetric temperature change due to discharge. The discharge inception voltages and the temperature variations for two salt droplets closely correlated with the ionization degree of the salt, as well as the interfacial electrochemical reactions near the electrodes. Mechanisms of these observed phenomena were discussed. PMID:27121926

  10. Sessile multidroplets and salt droplets under high tangential electric fields

    NASA Astrophysics Data System (ADS)

    Xie, Guoxin; He, Feng; Liu, Xiang; Si, Lina; Guo, Dan

    2016-04-01

    Understanding the interaction behaviors between sessile droplets under imposed high voltages is very important in many practical situations, e.g., microfluidic devices and the degradation/aging problems of outdoor high-power applications. In the present work, the droplet coalescence, the discharge activity and the surface thermal distribution response between sessile multidroplets and chloride salt droplets under high tangential electric fields have been investigated with infrared thermography, high-speed photography and pulse current measurement. Obvious polarity effects on the discharge path direction and the temperature change in the droplets in the initial stage after discharge initiation were observed due to the anodic dissolution of metal ions from the electrode. In the case of sessile aligned multidroplets, the discharge path direction could affect the location of initial droplet coalescence. The smaller unmerged droplet would be drained into the merged large droplet as a result from the pressure difference inside the droplets rather than the asymmetric temperature change due to discharge. The discharge inception voltages and the temperature variations for two salt droplets closely correlated with the ionization degree of the salt, as well as the interfacial electrochemical reactions near the electrodes. Mechanisms of these observed phenomena were discussed.

  11. Magnetic fields in galaxies at high redshifts

    NASA Astrophysics Data System (ADS)

    Bernet, Martin Leo; Gaensler, Bryan; Lilly, Simon; O'Sullivan, Shane; Miniati, Francesco

    2013-04-01

    We have recently demonstrated an association between high Faraday Rotation of radio quasars and the presence of intervening strong MgII absorption and determined that the magnetized plasma in the associated galaxies extends up to 60 kpc. These findings are based on Rotation Measure (RM) observations typically performed at 5 GHz, but they can not be reproduced using RMs obtained at lower frequencies, e.g. using the Taylor et al. (2009) RM catalogue at 1.4 GHz. This apparent discrepancy can be explained by a model which takes into account the depolarization of the sources due to inhomogeneous Faraday Rotation screens and their partial coverage of the sources. We propose here to observe 27 sources of our sample which are accessible by the ATCA to test this hypothesis. Our goal is to observe the selected sources over the broad frequency range 1.1 -10.8 GHz to obtain depolarization curves and to perform Faraday Rotation Measure Synthesis. With this sample we will be able to determine the homogeneity of the Faraday screens in the intervening galaxies and to further strengthen the original result. Finally the outcome of this experiment has important implications for the design of future RM surveys.

  12. Stud arc welding in a magnetic field - Investigation of the influences on the arc motion

    NASA Astrophysics Data System (ADS)

    Hartz-Behrend, K.; Marqués, J. L.; Forster, G.; Jenicek, A.; Müller, M.; Cramer, H.; Jilg, A.; Soyer, H.; Schein, J.

    2014-11-01

    Stud arc welding is widely used in the construction industry. For welding of studs with a diameter larger than 14 mm a ceramic ferrule is usually necessary in order to protect the weld pool. Disadvantages of using such a ferrule are that more metal is molten than necessary for a high quality welded joint and that the ferrule is a consumable generally thrown away after the welding operation. Investigations show that the ferrule can be omitted when the welding is carried out in a radially symmetric magnetic field within a shielding gas atmosphere. Due to the Lorentz force the arc is laterally shifted so that a very uniform and controlled melting of the stud contact surface as well as of the work piece can be achieved. In this paper a simplified physical model is presented describing how the parameters welding current, flux density of the magnetic field, radius of the arc and mass density of the shielding gas influence the velocity of the arc motion. The resulting equation is subsequently verified by comparing it to optical measurements of the arc motion. The proposed model can be used to optimize the required field distribution for the magnetic field stud welding process.

  13. Investigating Non-Equilibrium Fluctuations of Nanocolloids in a Magnetic Field Using Direct Imaging Methods

    NASA Astrophysics Data System (ADS)

    Rice, Ashley; Oprisan, Ana; Oprisan, Sorinel; Rice-Oprisan College of Charleston Team

    Nanoparticles of iron oxide have a high surface area and can be controlled by an external magnetic field. Since they have a fast response to the applied magnetic field, these systems have been used for numerous in vivo applications, such as MRI contrast enhancement, tissue repair, immunoassay, detoxification of biological fluids, hyperthermia, drug delivery, and cell separation. We performed three direct imaging experiments in order to investigate the concentration-driven fluctuations using magnetic nanoparticles in the absence and in the presence of magnetic field. Our direct imaging experimental setup involved a glass cell filled with magnetic nanocolloidal suspension and water with the concentration gradient oriented against the gravitational field and a superluminescent diode (SLD) as the light source. Nonequilibrium concentration-driven fluctuations were recorded using a direct imaging technique. We used a dynamic structure factor algorithm for image processing in order to compute the structure factor and to find the power law exponents. We saw evidence of large concentration fluctuations and permanent magnetism. Further research will use the correlation time to approximate the diffusion coefficient for the free diffusion experiment. Funded by College of Charleston Department of Undergraduate Research and Creative Activities SURF grant.

  14. Numerical investigation of the contraction of neutral-charged diblock copolymer brushes in electric fields.

    PubMed

    Chen, Yuwei; Li, Haiming; Zhu, Yuejin; Tong, Chaohui

    2016-03-31

    Using self-consistent field theory (SCFT), the contraction of neutral-charged A-B diblock copolymer brushes in electric fields generated by opposite surface charges on two parallel electrodes has been numerically investigated. The diblock copolymer chains were grafted with the free end of the neutral block to one electrode and immersed in a salt-free solution sandwiched between the two electrodes. The numerical results reveal that the charged monomers, A-B joint segment and the tail exhibit bimodal distributions under external electric fields, which are absent for homopolymer polyelectrolyte brushes. The dependences of the relative populations and peak positions of the two modes on various parameters such as block ratio, grafting density, chain length and strength of the applied electric field were systematically examined and the underlining mechanisms were elucidated. It was found in this study that, if the total amount of surface charges on the grafting electrode is no more than that of the counter-ions in the system, overall charge neutrality is generally maintained inside the brushes when including the contribution of surface charges on the grafting electrode. In such a case, the counter-ions expelled from the brushes are highly enriched in the immediate vicinity of the second electrode and an approximate charge balance between these expelled counter-ions and the opposite surface charges on the second electrode is achieved. PMID:26912335

  15. Investigating the active hydrothermal field of Kolumbo Volcano using CTD profiling

    NASA Astrophysics Data System (ADS)

    Eleni Christopoulou, Maria; Mertzimekis, Theo; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Carey, Steve

    2014-05-01

    The submarine Kolumbo volcano NE of Santorini Island and the unique active hydrothermal vent field on its crater field (depth ~ 500 m) have been recently explored in multiple cruises aboard E/V Nautilus. ROV explorations showed the existence of extensive vent activity and almost completely absence of vent-specific macrofauna. Gas discharges have been found to be 99%-rich in CO2, which is sequestered at the bottom of the crater due to a special combination of physicochemical and geomorphological factors. The dynamic conditions existing along the water column in the crater have been studied in detail by means of temperature, salinity and conductivity depth profiles for the first time. CTD sensors aboard the ROV Hercules were employed to record anomalies in those parameters in an attempt to investigate several active and inactive vent locations. Temporal CTD monitoring inside and outside of the crater was carried out over a period of two years. Direct comparison between the vent field and locations outside the main cone, where no hydrothermal activity is known to exist, showed completely different characteristics. CTD profiles above the active vent field (NNE side) are correlated to Kolumbo's cone morphology. The profiles suggest the existence of four distinct zones of physicochemical properties in the water column. The layer directly above the chimneys exhibit gas discharges highly enriched in CO2. Continuous gas motoring is essential to identify the onset of geological hazards in the region.

  16. High-resolution gravity field modeling using GRAIL mission data

    NASA Astrophysics Data System (ADS)

    Lemoine, F. G.; Goossens, S. J.; Sabaka, T. J.; Nicholas, J. B.; Mazarico, E.; Rowlands, D. D.; Neumann, G. A.; Loomis, B.; Chinn, D. S.; Smith, D. E.; Zuber, M. T.

    2015-12-01

    The Gravity Recovery and Interior Laboratory (GRAIL) spacecraft were designed to map the structure of the Moon through high-precision global gravity mapping. The mission consisted of two spacecraft with Ka-band inter-satellite tracking complemented by tracking from Earth. The mission had two phases: a primary mapping mission from March 1 until May 29, 2012 at an average altitude of 50 km, and an extended mission from August 30 until December 14, 2012, with an average altitude of 23 km before November 18, and 20 and 11 km after. High-resolution gravity field models using both these data sets have been estimated, with the current resolution being degree and order 1080 in spherical harmonics. Here, we focus on aspects of the analysis of the GRAIL data: we investigate eclipse modeling, the influence of empirical accelerations on the results, and we discuss the inversion of large-scale systems. In addition to global models we also estimated local gravity adjustments in areas of particular interest such as Mare Orientale, the south pole area, and the farside. We investigate the use of Ka-band Range Rate (KBRR) data versus numerical derivatives of KBRR data, and show that the latter have the capability to locally improve correlations with topography.

  17. Field emission behavior of carbon nanotube field emitters after high temperature thermal annealing

    SciTech Connect

    Sun, Yuning; Shin, Dong Hoon; Yun, Ki Nam; Leti, Guillaume; Hwang, Yeon Mo; Song, Yenan; Saito, Yahachi; Lee, Cheol Jin

    2014-07-15

    The carbon nanotube (CNT) field emitters have been fabricated by attaching a CNT film on a graphite rod using graphite adhesive material. The CNT field emitters showed much improved field emission properties due to increasing crystallinity and decreasing defects in CNTs after the high temperature thermal annealing at 900 °C in vacuum ambient. The CNT field emitters showed the low turn-on electric field of 1.15 V/μm, the low threshold electric field of 1.62 V/μm, and the high emission current of 5.9 mA which corresponds to a current density of 8.5 A/cm{sup 2}. In addition, the CNT field emitters indicated the enhanced field emission properties due to the multi-stage effect when the length of the graphite rod increases. The CNT field emitter showed good field emission stability after the high temperature thermal annealing. The CNT field emitter revealed a focused electron beam spot without any focusing electrodes and also showed good field emission repeatability.

  18. A High School Statistics Class Investigates the Death Penalty

    ERIC Educational Resources Information Center

    Brelias, Anastasia

    2015-01-01

    Recommendations for reforming high school mathematics curricula emphasize the importance of engaging students in mathematical investigations of societal issues (CCSSI [Common Core State Standards Initiative] 2010; NCTM [National Council of Teachers of Mathematics] 2000). Proponents argue that these investigations can positively influence students'…

  19. Torsional oscillations of neutron stars with highly tangled magnetic fields

    NASA Astrophysics Data System (ADS)

    Sotani, Hajime

    2015-11-01

    To determine the frequencies of magnetic oscillations in neutron stars with highly tangled magnetic fields, we derive the perturbation equations. We assume that the field strength of the global magnetic structure is so small that such fields are negligible compared with tangled fields, which may still be far from a realistic configuration. Then, we systematically examine the spectra of the magnetic oscillations, as varying the magnetic field strength and stellar mass. The frequencies without crust elasticity are completely proportional to the strength of the magnetic field, whose proportionality constant depends strongly on the stellar mass. On the other hand, the oscillation spectra with crust elasticity become more complicated, where the frequencies even for weak magnetic fields are different from the crustal torsional oscillations without magnetic fields. For discussing spectra, the critical field strength can play an important role, and it is determined in such a way that the shear velocity is equivalent to the Alfvén velocity at the crust basis. Additionally, we find that the effect of the crust elasticity can be seen strongly in the fundamental oscillations with a lower harmonic index, ℓ. Unlike the stellar models with a pure dipole magnetic field, we also find that the spectra with highly tangled magnetic fields become discrete, where one can expect many of the eigenfrequencies. Maybe these frequencies could be detected after the violent phenomena breaking the global magnetic field structure.

  20. Sampling of high amounts of bioaerosols using a high-volume electrostatic field sampler.

    PubMed

    Madsen, A M; Sharma, A K

    2008-04-01

    For studies of the biological effects of bioaerosols, large samples are necessary. To be able to sample enough material and to cover the variations in aerosol content during and between working days, a long sampling time is necessary. Recently, a high-volume transportable electrostatic field sampler for collection of fine particles has been described. The aim of this study was to investigate whether this sampler can be used for collection of high amounts of authentic bioaerosols that can subsequently be used for biological analysis. The investigation was carried out at a biofuel plant in a straw storage room and in a boiler room over two seasons. The sampled dust was quantified in terms of mass and characterized regarding microbial components and compared with dust sampled by Gravikon and GSP samplers. For the electrostatic field sampler, a prefilter was used to remove large objects. The prefilter was characterized for particle penetration and this testing indicated that the prefilter did not remove particles up to 10 mum, and therefore respirable dust was sampled by the electrostatic field sampler. Using the electrostatic field sampler in the straw storage and in the boiler room, 330 and 315 mg dust (net recovery of the lyophilized dust) was sampled during a period of 7 days, respectively. The sampling rates of the electrostatic field samplers were between 1.34 and 1.96 mg dust per hour, the value for the Gravikon was between 0.083 and 0.108 mg dust per hour and the values for the GSP samplers were between 0.0031 and 0.032 mg dust per hour. The standard deviations of replica samplings and the following microbial analysis using the electrostatic field sampler and GSP samplers were at the same levels. The exposure to dust in the straw storage was 7.7 mg m(-3) when measured by the electrostatic field sampler and 11.8 mg m(-3) when measured by the GSP inhalable dust sampler. The quantity (amount per mg dust) of total fungi, Aspergillus fumigatus, total bacteria

  1. HIGH FIELD Q-SLOPE AND THE BAKING EFFECT

    SciTech Connect

    Ciovati, Gianluigi

    2009-11-01

    The performance of SRF cavities made of bulk Nb at high fields (peak surface magnetic field greater than about 90 mT) is characterized by exponentially increasing RF losses (high-field Q-slope), in the absence of field emission, which are often mitigated by a low temperature (100-140 °C, 12-48h) baking. In this contribution, recent experimental results and phenomenological models to explain this effect will be briefly reviewed. New experimental results on the high-field Q-slope will be presented for cavities that had been heat treated at high temperature in the presence of a small partial pressure of nitrogen. Improvement of the cavity performances have been obtained, while surface analysis measurements on Nb samples treated with the cavities revealed significantly lower hydrogen concentration than for samples that followed standard cavity treatments.

  2. Experimental investigation of a simulated LOX injector flow field and other nonintrusive measurement efforts

    NASA Astrophysics Data System (ADS)

    Hartfield, Roy J., Jr.

    1992-12-01

    Efforts to improve the characteristics of fuel-oxidizer mixing in liquid rocket combustors have lead to a swirl element design for a liquid oxygen injector which is being considered for use on the STME. For the design which is the subject of this investigation, the oxygen enters the injector element perpendicular to the injector axis and nearly tangent to the circular injector wall. This swirl element is at one end of a tube and the injector exit is at the other. This geometric configuration creates a plume in the shape of a conical sheet. This sheet is either primarily contiguous liquid or droplets depending on the pressure drop in the injector and the distance from the injector exit. Probe-based devices such as two-dimensional grid patternators have been used to investigate simulated LOX injector flow fields (Hulka). The primary work described herein is an effort to use optical techniques to investigate the plume of a swirl injector element. For this investigation, a high pressure (500 psig) cold flow test facility was constructed. Water was used as the LOX simulate and air pressure was used to drive the injector flow field. Laser-induced fluorescence (LIF) from dye seeded into the water was used to obtain quantitative measurements of the time-averaged water concentration distribution in the plume. Scattered laser light and LIF were used for time averaged plume visualization and scattered light from a strobe with a 1 microsecond pulse was used for time-resolved plume visualization. During the Summer Faculty Fellowship for which this report was developed, an additional effort, unrelated to the swirl injector investigation, was made to resolve fluctuations in the combustion product composition in the exhaust of a hybrid rocket motor. A brief description of this effort is included herein.

  3. High-field paramagnetic Meissner effect in melt-textured YBCO

    NASA Astrophysics Data System (ADS)

    Dias, F. T.; Pureur, P.; Rodrigues, P.; Obradors, X.

    2004-08-01

    We present systematic field-cooled magnetization measurements in four directionally solidified samples of YBCO containing different amounts of Y211 precipitates. Fields up to 50 kOe were applied either parallel or perpendicular to the Cu-O 2 atomic planes. At high applied magnetic fields, the paramagnetic Meissner effect (PME) was observed in all of the studied samples, regardless of the field orientation with respect to the crystalline axes. This high-field PME shows some noticeable differences when compared to the most frequently investigated PME at low applied fields. Our results suggest that pinning by Y211 particles is important for explaining the high-field PME of melt-processed YBCO.

  4. Experimental investigation of mechanisms of mid-latitude ionosphere and geophysical fields perturbation

    NASA Astrophysics Data System (ADS)

    Gavrilov, Boris; Zetzer, Julius; Egorov, Dmitry

    The investigations are carried out to study mechanisms and channels of the mid-latitude ionosphere, near-Earth electric field and current perturbations, and their connection to high-latitude and magnetospheric events. The basis of these investigations is a measurement of the geophysical fields in the Geophysical Observatory Mikhnevo (54.9 N, 37,8 E) of the Institute of Geospheres Dynamics RAS situated at 80 km to the south from Moscow. The observatory includes a set of measuring complexes for radiophysics, magnetic, electrical, optic, infrasound, seismic, and other investigations. All of them are controlled by the united computer centre in the common scale of time. Our approach bases on well known conception that the main reasons of the mid-latitude perturbations are the processes in the auroral regions. But auroral phenomena impact on mid-latitudes by means of different physical mechanisms and agents of disturbances. Fortunately, they differ from each other in the time of their generation and velocities of their propagation. For example, the typical velocity of propagation of thermosphere winds is about 100 m/s, the acoustic gravity wave propagate with a velocity of about 400 m/s, and a prompt penetration of the magnetospheric electric field affects the mid-latitude practically instantly. If we can determine a time lag between the action of the perturbation source and mid-latitude ionosphere response, we can determine the velocity of perturbation propagation and recognize the dominating mechanisms and channels of disturbances. The important requirements for the organization of such investigation is a positioning of different measuring facilities in one place and organization of coordinated and synchronous registration of the ionosphere parameters and geophysical fields variations with high temporal resolution. The Mikhnevo observatory gives us such ability. As an indicator and marker of high latitude events (magnetic storms and substorms) we use AE-index. The

  5. Effect of a High Magnetic Field on Microstructures of Ni-Based Single Crystal Superalloy During Seed Melt-Back

    NASA Astrophysics Data System (ADS)

    Xuan, Weidong; Liu, Huan; Li, Chuanjun; Ren, Zhongming; Zhong, Yunbo; Li, Xi; Cao, Guanghui

    2016-04-01

    The effects of a high magnetic field on microstructures during seed melt-back of superalloy were investigated. Experimental results indicated that the high magnetic field significantly modified the melt-back interface shape and the melt-back zone length. In addition, stray grain on the edge of sample was effectively suppressed in the high magnetic field. Based on experimental results and quantitative analysis, the above results should be attributed to the increasing temperature gradient in a high magnetic field.

  6. High critical field NbC superconductor on carbon spheres.

    PubMed

    Bhattacharjee, Kaustav; Pati, Satya Prakash; Maity, Arjun

    2016-06-01

    Niobium carbide (NbC) nanoparticles embedded on the surface of carbon spheres (CS) were synthesized at 1350 °C by the carbothermal reduction of niobium oxide precursor in flowing argon (Nbc@CS). The morphology, crystal structure, and magnetic properties of the hybrid nanocomposite were investigated by means of electron microscopy, X-ray diffraction and a superconducting quantum interference device. It was found that the NbC@CS nanocomposites exhibit type-II superconductivity with a critical temperature (Tc) of 8-12 K, typical for stoichiometric NbC. The superconducting hysteresis loop reveals several interesting traits, including strong vortex pinning, the presence of asymmetry and a high penetration field. Moreover, the sample shows much improved irreversible (Hirr), lower (Hc1) and upper (Hc2) critical fields. The coherence length (ξ), penetration depth (λ), and Ginzburg-Landau (κ) parameters for the sample were estimated to be 9.78 nm, 33 nm and 3.39, respectively. PMID:27212586

  7. Advanced measurements and techniques in high magnetic fields

    SciTech Connect

    Campbell, L.J.; Rickel, D.G.; Lacerda, A.H.; Kim, Y.

    1997-07-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). High magnetic fields present a unique environment for studying the electronic structure of materials. Two classes of materials were chosen for experiments at the national high Magnetic Field Laboratory at Los Alamos: highly correlated electron systems and semiconductors. Magnetotransport and thermodynamic experiments were performed on the renormalized ground states of highly correlated electron systems (such as heavy fermion materials and Kondo insulators) in the presence of magnetic fields that are large enough to disrupt the many-body correlations. A variety of optical measurements in high magnetic fields were performed on semiconductor heterostructures including GaAs/AlGaAs single heterojunctions (HEMT structure), coupled double quantum wells (CDQW), asymmetric coupled double quantum wells (ACDQW), multiple quantum wells and a CdTe single crystal thin film.

  8. Experimental Investigation of Pool Boiling Heat Transfer Enhancement in Microgravity in the Presence of Electric Fields

    NASA Technical Reports Server (NTRS)

    Herman, Cila

    1996-01-01

    Boiling is an effective mode of heat transfer since high heat flux levels are possible driven by relatively small temperature differences. The high heat transfer coefficients associated with boiling have made the use of these processes increasingly attractive to aerospace engineering. Applications of this type include compact evaporators in the thermal control of aircraft avionics and spacecraft environments, heat pipes, and use of boiling to cool electronic equipment. In spite of its efficiency, cooling based on liquid-vapor phase change processes has not yet found wide application in aerospace engineering due to specific problems associated with the low gravity environment. After a heated surface has reached the superheat required for the initiation of nucleate boiling, bubbles will start forming at nucleation sites along the solid interface by evaporation of the liquid. Bubbles in contact with the wall will continue growing by this mechanism until they detach. In terrestrial conditions, bubble detachment is determined by the competition between body forces (e.g. buoyancy) and surface tension forces that act to anchor the bubble along the three phase contact line. For a given body force potential and a balance of tensions along the three phase contact line, bubbles must reach a critical size before the body force can cause them to detach from the wall. In a low gravity environment the critical bubble size for detachment is much larger than under terrestrial conditions, since buoyancy is a less effective means of bubble removal. Active techniques of heat transfer enhancement in single phase and phase change processes by utilizing electric fields have been the subject of intensive research during recent years. The field of electrohydrodynamics (EHD) deals with the interactions between electric fields, flow fields and temperature fields. Previous studies indicate that in terrestrial applications nucleate boiling heat transfer can be increased by a factor of 50 as

  9. Remedial investigation sampling and analysis plan for J-Field, Aberdeen Proving Ground, Maryland. Volume 1: Field Sampling Plan

    SciTech Connect

    Benioff, P.; Biang, R.; Dolak, D.; Dunn, C.; Martino, L.; Patton, T.; Wang, Y.; Yuen, C.

    1995-03-01

    The Environmental Management Division (EMD) of Aberdeen Proving Ground (APG), Maryland, is conducting a remedial investigation and feasibility study (RI/FS) of the J-Field area at APG pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended. J-Field is within the Edgewood Area of APG in Harford County, Maryland (Figure 1. 1). Since World War II activities in the Edgewood Area have included the development, manufacture, testing, and destruction of chemical agents and munitions. These materials were destroyed at J-Field by open burning and open detonation (OB/OD). Considerable archival information about J-Field exists as a result of efforts by APG staff to characterize the hazards associated with the site. Contamination of J-Field was first detected during an environmental survey of the Edgewood Area conducted in 1977 and 1978 by the US Army Toxic and Hazardous Materials Agency (USATHAMA) (predecessor to the US Army Environmental Center [AEC]). As part of a subsequent USATHAMA -environmental survey, 11 wells were installed and sampled at J-Field. Contamination at J-Field was also detected during a munitions disposal survey conducted by Princeton Aqua Science in 1983. The Princeton Aqua Science investigation involved the installation and sampling of nine wells and the collection and analysis of surficial and deep composite soil samples. In 1986, a Resource Conservation and Recovery Act (RCRA) permit (MD3-21-002-1355) requiring a basewide RCRA Facility Assessment (RFA) and a hydrogeologic assessment of J-Field was issued by the US Environmental Protection Agency (EPA). In 1987, the US Geological Survey (USGS) began a two-phased hydrogeologic assessment in data were collected to model, groundwater flow at J-Field. Soil gas investigations were conducted, several well clusters were installed, a groundwater flow model was developed, and groundwater and surface water monitoring programs were established that continue today.

  10. Spontaneous Radiation Emission from Short, High Field Strength Insertion Devices

    SciTech Connect

    Geoffrey Krafft

    2005-09-15

    Since the earliest papers on undulaters were published, it has been known how to calculate the spontaneous emission spectrum from ''short'' undulaters when the magnetic field strength parameter is small compared to unity, or in ''single'' frequency sinusoidal undulaters where the magnetic field strength parameter is comparable to or larger than unity, but where the magnetic field amplitude is constant throughout the undulater. Fewer general results have been obtained in the case where the insertion device is both short, i.e., the magnetic field strength parameter changes appreciably throughout the insertion device, and the magnetic field strength is high enough that ponderomotive effects, radiation retardation, and harmonic generation are important physical phenomena. In this paper a general method is presented for calculating the radiation spectrum for short, high-field insertion devices. It is used to calculate the emission from some insertion device designs of recent interest.

  11. Study of HTS Insert Coils for High Field Solenoids

    SciTech Connect

    Lombardo, Vito; /Fermilab

    2009-09-01

    Fermilab is currently working on the development of high field magnet systems for ionization cooling of muon beams. The use of high temperature superconducting materials (HTS) is being considered for these solenoids using Helium refrigeration. Several studies have been performed on insert coils made of BSCCO-2223 tapes and second generation (2G) YBCO coated conductors, which are tested at various temperatures and at external fields of up to 14 T. Critical current (I{sub c}) measurements of YBCO short samples are presented as a function of bending stress, magnetic field and field orientation with respect to the sample surface. An analytical fit of critical current data as a function of field and field orientation is also presented. Results from several single-layer and double-layer pancake coils are also discussed.

  12. High magnetic field processing of liquid crystalline polymers

    DOEpatents

    Smith, Mark E.; Benicewicz, Brian C.; Douglas, Elliot P.

    1998-01-01

    A process of forming bulk articles of oriented liquid crystalline thermoset material, the material characterized as having an enhanced tensile modulus parallel to orientation of an applied magnetic field of at least 25 percent greater than said material processed in the absence of a magnetic field, by curing a liquid crystalline thermoset precursor within a high strength magnetic field of greater than about 2 Tesla, is provided, together with a resultant bulk article of a liquid crystalline thermoset material, said material processed in a high strength magnetic field whereby said material is characterized as having a tensile modulus parallel to orientation of said field of at least 25 percent greater than said material processed in the absence of a magnetic field.

  13. High magnetic field processing of liquid crystalline polymers

    DOEpatents

    Smith, M.E.; Benicewicz, B.C.; Douglas, E.P.

    1998-11-24

    A process of forming bulk articles of oriented liquid crystalline thermoset material, the material characterized as having an enhanced tensile modulus parallel to orientation of an applied magnetic field of at least 25 percent greater than said material processed in the absence of a magnetic field, by curing a liquid crystalline thermoset precursor within a high strength magnetic field of greater than about 2 Tesla, is provided, together with a resultant bulk article of a liquid crystalline thermoset material, said material processed in a high strength magnetic field whereby said material is characterized as having a tensile modulus parallel to orientation of said field of at least 25 percent greater than said material processed in the absence of a magnetic field.

  14. Strong magnetic fields in normal galaxies at high redshift

    NASA Astrophysics Data System (ADS)

    Bernet, Martin L.; Miniati, Francesco; Lilly, Simon J.; Kronberg, Philipp P.; Dessauges-Zavadsky, Miroslava

    2008-07-01

    The origin and growth of magnetic fields in galaxies is still something of an enigma. It is generally assumed that seed fields are amplified over time through the dynamo effect, but there are few constraints on the timescale. It was recently demonstrated that field strengths as traced by rotation measures of distant (and hence ancient) quasars are comparable to those seen today, but it was unclear whether the high fields were in the unusual environments of the quasars themselves or distributed along the lines of sight. Here we report high-resolution spectra that demonstrate that the quasars with strong MgII absorption lines are unambiguously associated with larger rotation measures. Because MgII absorption occurs in the haloes of normal galaxies along the sightlines to the quasars, this association requires that organized fields of surprisingly high strengths are associated with normal galaxies when the Universe was only about one-third of its present age.

  15. Thermodynamic critical fields in high T c superconductivity

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.; Johnson, Keith H.

    1988-06-01

    Using the free electron approximation, a real space mechanism of how magnetic fields of sufficient strength destroy the superconducting state is outlined. Using the resultant equation together with the molecular orbital model of superconductivity 1,2, the thermodynamic critical magnetic field is calculated and compared to experiment for type I elemental superconductors and type II superconductors, including high-Tc superconductors. The expression for critical field compares favorably with an expression derived by Schrieffer.

  16. Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

    DOEpatents

    Westerfield, Curtis L.; Morris, John S.; Agnew, Stephen F.

    1997-01-01

    Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear.

  17. Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

    DOEpatents

    Westerfield, C.L.; Morris, J.S.; Agnew, S.F.

    1997-01-14

    Diamond anvil cell is described for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear. 4 figs.

  18. Field-effect transistor having a superlattice channel and high carrier velocities at high applied fields

    DOEpatents

    Chaffin, R.J.; Dawson, L.R.; Fritz, I.J.; Osbourn, G.C.; Zipperian, T.E.

    1984-04-19

    In a field-effect transistor comprising a semiconductor having therein a source, a drain, a channel and a gate in operational relationship, there is provided an improvement wherein said semiconductor is a superlattice comprising alternating quantum well and barrier layers, the quantum well layers comprising a first direct gap semiconductor material which in bulk form has a certain bandgap and a curve of electron velocity versus applied electric field which has a maximum electron velocity at a certain electric field, the barrier layers comprising a second semiconductor material having a bandgap wider than that of said first semiconductor material, wherein the layer thicknesses of said quantum well and barrier layers are sufficiently thin that the alternating layers constitute a superlattice having a curve of electron velocity versus applied electric field which has a maximum electron velocity at a certain electric field, and wherein the thicknesses of said quantum well layers are selected to provide a superlattice curve of electron velocity versus applied electric field whereby, at applied electric fields higher than that at which the maximum electron velocity occurs in said first material when in bulk form, the electron velocities are higher in said superlattice than they are in said first semiconductor material in bulk form.

  19. Field Trips as Cognitive Motivators for High Level Science Learning

    ERIC Educational Resources Information Center

    Hurley, Marlene M.

    2006-01-01

    Using a composite example of field trips from several years of traveling to Yellowstone with high school biology students, the author illustrates how to raise the cognitive level of science instruction and student learning through science field trips. The author examines what teachers can do to raise the level of both teaching and learning in all…

  20. Radioactive waste storage in mined caverns in crystalline rock: results of field investigations at Stripa, Sweden

    SciTech Connect

    Witherspoon, P.A.

    1980-10-01

    It is generally agreed that the most practicable method of isolating nuclear wastes from the biosphere is by deep burial in suitable geologic formations. Such burial achieves a high degree of physical isolation but raises questions concerning the rate at which some of these wastes may return to the biosphere through transport by groundwater. Any suitable repository site will be disturbed first by excavation and second by the thermal pulse caused by the radioactive decay of the wastes. To assess the effectiveness of geologic isolation it is necessary to develop the capability of predicting the response of a rock mass to such a thermal pulse. Ultimately, this requires field measurements below the surface in media representative of those likely to be encountered at an actual repository. Access to a granitic rock mass adjacent to a defunct iron ore mine at Stripa, Sweden, at a depth of about 350 m below surface has provided a unique opportunity to conduct a comprehensive suite of hydrological and thermo-mechanical experiments under such conditions. The results of these field tests have shown the importance of geologic structure and the functional dependence of the thermo-mechanical properties on temperature in developing a valid predictive model. The results have also demonstrated the vital importance of carrying out large-scale investigations in a field test facility.

  1. Experimental Investigation of Pool Boiling Heat Transfer Enhancement in Microgravity in the Presence of Electric Fields

    NASA Technical Reports Server (NTRS)

    Herman, Cila

    1999-01-01

    In boiling high heat fluxes are possible driven by relatively small temperature differences, which make its use increasingly attractive in aerospace applications. The objective of the research is to develop ways to overcome specific problems associated with boiling in the low gravity environment by substituting the buoyancy force with the electric force to enhance bubble removal from the heated surface. Previous studies indicate that in terrestrial applications nucleate boiling heat transfer can be increased by a factor of 50, as compared to values obtained for the same system without electric fields. The goal of our research is to experimentally explore the mechanisms responsible for EHD heat transfer enhancement in boiling in low gravity conditions, by visualizing the temperature distributions in the vicinity of the heated surface and around the bubble during boiling using real-time holographic interferometry (HI) combined with high-speed cinematography. In the first phase of the project the influence of the electric field on a single bubble is investigated. Pool boiling is simulated by injecting a single bubble through a nozzle into the subcooled liquid or into the thermal boundary layer developed along the flat heater surface. Since the exact location of bubble formation is known, the optical equipment can be aligned and focused accurately, which is an essential requirement for precision measurements of bubble shape, size and deformation, as well as the visualization of temperature fields by HI. The size of the bubble and the frequency of bubble departure can be controlled by suitable selection of nozzle diameter and mass flow rate of vapor. In this approach effects due to the presence of the electric field can be separated from effects caused by the temperature gradients in the thermal boundary layer. The influence of the thermal boundary layer can be investigated after activating the heater at a later stage of the research. For the visualization experiments a

  2. Design of High Field Solenoids made of High Temperature Superconductors

    SciTech Connect

    Bartalesi, Antonio; /Pisa U.

    2010-12-01

    This thesis starts from the analytical mechanical analysis of a superconducting solenoid, loaded by self generated Lorentz forces. Also, a finite element model is proposed and verified with the analytical results. To study the anisotropic behavior of a coil made by layers of superconductor and insulation, a finite element meso-mechanic model is proposed and designed. The resulting material properties are then used in the main solenoid analysis. In parallel, design work is performed as well: an existing Insert Test Facility (ITF) is adapted and structurally verified to support a coil made of YBa{sub 2}Cu{sub 3}O{sub 7}, a High Temperature Superconductor (HTS). Finally, a technological winding process was proposed and the required tooling is designed.

  3. High-gain reverse guide field free electron lasers

    SciTech Connect

    Tsui, K.H.

    1995-10-01

    Electron beam trajectories under circularly polarized external wigglers in free electron laser devices with axial guide fields are reconsidered by introducing the self-fields of the electron beam. The competition between the self-fields and the wiggler field plus the action of the guide field are not only responsible for the known positive guide field singularity, but also the new reverse guide field singularity. The physics of the new reverse field singularity relies on the fact that an azimuthal magnetic field uniform in {ital z} is able to generate steady-state helical beam orbits just as if it were a transverse wiggler. According to this theory, the handness of the circularly polarized microwave should depend on the guide field configuration. High-gain strong pump equations coupled to these trajectories are used to account for the Massachusetts Institute of Technology reverse guide field results [Phys. Rev. Lett. {bold 67}, 3082 (1991)]. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  4. High electric field measurement using slab-coupled optical sensors.

    PubMed

    Stan, Nikola; Seng, Frederick; Shumway, LeGrand; King, Rex; Selfridge, Richard; Schultz, Stephen

    2016-01-20

    A fiber-optic electric field sensor was developed to measure electric field up to 18 MV/m. The sensor uses resonant coupling between an optical fiber and a nonlinear electro-optical crystal. The sensing system uses high dielectric strength materials to eliminate dielectric breakdown. A postprocessing nonlinear calibration method is developed that maps voltage change to wavelength shift and then converts the wavelength shift to electric field using the transmission spectrum. The nonlinear calibration method is compared against the linear method with electric field pulses having magnitudes from 1.5 to 18 MV/m. PMID:26835936

  5. Mitigated-force carriage for high magnetic field environments

    SciTech Connect

    Ludtka, Gerard M.; Ludtka, Gail M.; Wilgen, John B.; Murphy, Bart L.

    2015-05-19

    A carriage for high magnetic field environments includes a plurality of work-piece separators disposed in an operable relationship with a work-piece processing magnet having a magnetic field strength of at least 1 Tesla for supporting and separating a plurality of work-pieces by a preselected, essentially equal spacing, so that, as a first work-piece is inserted into the magnetic field, a second work-piece is simultaneously withdrawn from the magnetic field, so that an attractive magnetic force imparted on the first work-piece offsets a resistive magnetic force imparted on the second work-piece.

  6. Stabilization of single-electron pumps by high magnetic fields

    NASA Astrophysics Data System (ADS)

    Fletcher, J. D.; Kataoka, M.; Giblin, S. P.; Park, Sunghun; Sim, H.-S.; See, P.; Ritchie, D. A.; Griffiths, J. P.; Jones, G. A. C.; Beere, H. E.; Janssen, T. J. B. M.

    2012-10-01

    We demonstrate theoretically and experimentally how magnetic fields influence the single-electron tunneling dynamics in electron pumps, giving a massively enhanced quantization accuracy and providing a route to a quantum current standard based on the elementary charge. The field dependence is explained by two effects: field-induced changes in the sensitivity of tunneling rates to the barrier potential and the suppression of nonadiabatic excitations due to a reduced sensitivity of the Fock-Darwin states to the electrostatic potential. These effects lead to a continued improvement in quantisation accuracy at high field which is important for applications in metrology.

  7. Astrophysical dynamos and the growth of magnetic fields in high-redshift galaxies

    NASA Astrophysics Data System (ADS)

    Rieder, Michael; Teyssier, Romain

    2015-08-01

    The origin and evolution of magnetic fields in the Universe is still an open question. Observations of galaxies at high-redshift give evidence for strong galactic magnetic fields even in the early Universe which are consistently measured at later times up to the present age. However, primordial magnetic fields and seed field generation by battery processes cannot explain such high field strengths, suggesting the presence of a rapid growth mechanism in those high-redshift galaxies and subsequent maintenance against decay. Astrophysical dynamo theory provides efficient means of field amplification where even weak initial fields can grow exponentially on sufficiently fast timescales, driving the conversion of kinetic energy into magnetic energy. We investigate the role which feedback mechanisms play in the creation of the turbulence necessary for dynamos to operate. Performing magnetohydrodynamic simulations of cooling halos of dwarf and Milky Way-like high-redshift progenitors, we compare the magnetic field evolution of weak seed fields with various topologies and stellar feedback mechanisms. We find that strong feedback can drive galactic gas turbulence which gives rise to velocity fields with fast exponential magnetic field growth. The simulations display a high gas fraction and a clumpy morphology with kinematics resembling Kolmogorov turbulence and magnetic energy spectra as predicted by Kazantsev dynamo theory. Magnetic fields reach equipartition with $\\mu$G field strength. In a final quiescent phase where feedback is turned off, gas turbulence is reduced and a quadrupole symmetry is observed in the magnetic field. These findings support the theory of rapid magnetic field amplification inside high-redshift galaxies, when the Universe was still young.

  8. High Magnetic Field-Induced Formation of Banded Microstructures in Lamellar Eutectic Alloys During Directional Solidification

    NASA Astrophysics Data System (ADS)

    Li, Xi; Fautrelle, Yves; Gagnoud, Annie; Ren, Zhongming; Moreau, Rene

    2016-06-01

    The influences of high magnetic field (up to 12 T) on the morphology of Pb-Sn and Al-Al2Cu lamellar eutectics during directional solidification were investigated. The experimental results indicate that, along with a decrease in eutectic spacing, the banded structure forms at lower growth speeds under high magnetic field and the band spacing decreases as the magnetic field increases. Moreover, the application of a magnetic field enriches the Cu solute in the liquid ahead of the liquid/solid interface during directional solidification of an Al-Al2Cu eutectic alloy. The effects of high magnetic field on the eutectic points of non-ferromagnetic alloys and the stress acting on the eutectic lamellae during directional solidification have been studied. Both thermodynamic evaluation and DTA measurements reveal that the high magnetic field has a negligible effect on the eutectic points of non-ferromagnetic alloys. However, the high magnetic field caused an increase of the nucleation temperature and undercooling. The numerical results indicate that a considerable stress is produced on the eutectic lamellae during directional solidification under high magnetic field. The formation of a banded structure in a lamellar eutectic during directional solidification under high magnetic field may be attributed to both the buildup of the solute in the liquid ahead of the liquid/solid interface and the stress acting on the eutectic lamellae.

  9. High Magnetic Field-Induced Formation of Banded Microstructures in Lamellar Eutectic Alloys During Directional Solidification

    NASA Astrophysics Data System (ADS)

    Li, Xi; Fautrelle, Yves; Gagnoud, Annie; Ren, Zhongming; Moreau, Rene

    2016-08-01

    The influences of high magnetic field (up to 12 T) on the morphology of Pb-Sn and Al-Al2Cu lamellar eutectics during directional solidification were investigated. The experimental results indicate that, along with a decrease in eutectic spacing, the banded structure forms at lower growth speeds under high magnetic field and the band spacing decreases as the magnetic field increases. Moreover, the application of a magnetic field enriches the Cu solute in the liquid ahead of the liquid/solid interface during directional solidification of an Al-Al2Cu eutectic alloy. The effects of high magnetic field on the eutectic points of non-ferromagnetic alloys and the stress acting on the eutectic lamellae during directional solidification have been studied. Both thermodynamic evaluation and DTA measurements reveal that the high magnetic field has a negligible effect on the eutectic points of non-ferromagnetic alloys. However, the high magnetic field caused an increase of the nucleation temperature and undercooling. The numerical results indicate that a considerable stress is produced on the eutectic lamellae during directional solidification under high magnetic field. The formation of a banded structure in a lamellar eutectic during directional solidification under high magnetic field may be attributed to both the buildup of the solute in the liquid ahead of the liquid/solid interface and the stress acting on the eutectic lamellae.

  10. Carrier Tunneling in High-Frequency Electric Fields

    SciTech Connect

    Ganichev, S.D.; Ziemann, E.; Gleim, T.; Prettl, W.; Ganichev, S.D.; Yassievich, I.N.; Perel, V.I.; Wilke, I.; Haller, E.E.

    1998-03-01

    An enhancement of tunnel ionization of deep impurities in semiconductors in an alternating field as compared to static fields has been observed. The transition between the quasistatic and the high-frequency regime is determined by the tunneling time. For the case of deep impurities this is the time of redistribution of the defect vibrational system which depends strongly on temperature and the impurity structure. A theory of tunnel ionization of deep impurities by high-frequency fields has been developed. {copyright} {ital 1998} {ital The American Physical Society}

  11. Experimental and theoretical investigation of high gradient acceleration

    SciTech Connect

    Bekefi, G.; Chen, C.; Chen, S.; Danly, B.; Temkin, R.J.; Wurtele, J.S.

    1992-02-01

    This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-FG0291ER-40648. Experimental and Theoretical Investigations of High Gradient Acceleration.'' This grant supports three research tasks: Task A consists of the design and fabrication of a 17GHz of photocathode gun, Task B supports the testing of high gradient acceleration using a 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders. This report is organized as follows. The development of an rf gun design and research progress on the picosecond laser system is summarized in Sec. 2, the status of the studies of the LBL/Haimson high gradient structure, using a 50 MW free-electron laser is summarized in Sec. 3, and theoretical research progress is described in Sec. 4. Supporting material is contained in Appendices A-G.

  12. High-frequency electric field measurement using a toroidal antenna

    DOEpatents

    Lee, Ki Ha

    2002-01-01

    A simple and compact method and apparatus for detecting high frequency electric fields, particularly in the frequency range of 1 MHz to 100 MHz, uses a compact toroidal antenna. For typical geophysical applications the sensor will be used to detect electric fields for a wide range of spectrum starting from about 1 MHz, in particular in the frequency range between 1 to 100 MHz, to detect small objects in the upper few meters of the ground. Time-varying magnetic fields associated with time-varying electric fields induce an emf (voltage) in a toroidal coil. The electric field at the center of (and perpendicular to the plane of) the toroid is shown to be linearly related to this induced voltage. By measuring the voltage across a toroidal coil one can easily and accurately determine the electric field.

  13. Pushing the Limits: RF Field Control at High Loaded Q

    SciTech Connect

    M. Liepe; S.A. Belomestnykh; J. Dobbins; R.P.K. Kaplan; C.R. Strohman; B.K. Stuhl; C. Hovater; T. Plawski

    2005-05-16

    The superconducting cavities in an Energy-Recovery-Linac will be operated with a high loaded Q of several 10{sup 7}, possible up to 10{sup 8}. Not only has no prior control system ever stabilized the RF field in a linac cavity with such high loaded Q, but also highest field stability in amplitude and phase is required at this high loaded Q. Because of a resulting bandwidth of the cavity of only a few Hz, this presents a significant challenge: the field in the cavity extremely sensitive to any perturbation of the cavity resonance frequency due to microphonics and Lorentz force detuning. To prove that the RF field in a high loaded Q cavity can be stabilized, and that Cornell's newly developed digital control system is able to achieve this, the system was connected to a high loaded Q cavity at the JLab IR-FEL. Excellent cw field stability--about 10{sup -4} rms in relative amplitude and 0.02 deg rms in phase--was achieved at a loaded Q of 2.1 x 10{sup 7} and 1.2 x 10{sup 8}, setting a new record in high loaded Q operation of a linac cavity. Piezo tuner based cavity frequency control proved to be very effective in keeping the cavity on resonance and allowed reliable to ramp up to high gradients in less than 1 second.

  14. Gaussian beam decomposition of high frequency wave fields

    SciTech Connect

    Tanushev, Nicolay M. Engquist, Bjoern; Tsai, Richard

    2009-12-10

    In this paper, we present a method of decomposing a highly oscillatory wave field into a sparse superposition of Gaussian beams. The goal is to extract the necessary parameters for a Gaussian beam superposition from this wave field, so that further evolution of the high frequency waves can be computed by the method of Gaussian beams. The methodology is described for R{sup d} with numerical examples for d=2. In the first example, a field generated by an interface reflection of Gaussian beams is decomposed into a superposition of Gaussian beams. The beam parameters are reconstructed to a very high accuracy. The data in the second example is not a superposition of a finite number of Gaussian beams. The wave field to be approximated is generated by a finite difference method for a geometry with two slits. The accuracy in the decomposition increases monotonically with the number of beams.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. FIELD INVESTIGATIONS OF CONCENTRATED ANIMAL FEEDING OPERATIONS (CAFOs): AUGUST 2007 – SEPTEMBER 2008

    EPA Science Inventory

    Field investigations of CAFO sites conducted by the Region 4 Science and Ecosystem Support Division involve identifying, sampling, and characterizing the level of microbiological and chemical contamination in surface water, groundwater, and sediment in areas surrounding the CAFO ...

  17. RAPID ARSENITE OXIDATION BY THERMUS AQUATICUS AND THERMUS THERMOPHILUS: FIELD AND LABORATORY INVESTIGATIONS. (R826189)

    EPA Science Inventory

    Thermus aquaticus and Thermus thermophilus, common inhabitants of terrestrial hot springs and thermally polluted domestic and industrial waters, have been found to rapidly oxidize arsenite to arsenate. Field investigations at a hot spring in Yellowstone National Park revealed ...

  18. FIELD INVESTIGATIONS OF CONFINED ANIMAL FEED LOT OPERATIONS (CAFO): OCTOBER 2005 – SEPTEMBER 2006

    EPA Science Inventory

    Field investigations include identifying, sampling, and characterizing the level of microbiological and chemical contamination in surface water, groundwater, and sediment in areas surrounding CAFO sites. Study sites for this reporting period included the Turner Road Site in Cleve...

  19. A novel high-sensitivity electrostatic biased electric field sensor

    NASA Astrophysics Data System (ADS)

    Huang, Jing'ao; Wu, Xiaoming; Wang, Xiaohong; Yan, Xiaojun; Lin, Liwei

    2015-09-01

    In this paper, an electric field sensor (EFS) with high sensitivity is proposed for low-frequency weak-strength ac electric field (E-field) measurements. The EFS is based on a piezoelectric cantilever biased by a strong electrostatic field. The electrostatic bias can enhance the electric field force of a weak ac E-field, thus the cantilever can oscillate in a weak ac E-field and the device sensitivity improves. Theoretical analyses have been established and suggest that a stronger strength of electrostatic field bias would produce a higher sensitivity improvement. In the experiment, a demonstrated sensor consisting of a polyvinylidene fluoride (PVDF) piezoelectric cantilever and a polytetrafluoroethylene (PTFE) electret was built and tested. Instead of extra voltage sources, the PTFE electret was charged to provide the electrostatic field, allowing the EFS a low energy consumption and a simple electric circuit design. The experiment results show good agreement with the simulation. The sensitivity of the cantilever E-field sensor reached 0.84 mV (kV/m)-1 when the surface potential of the electret was  -770 V.

  20. Toward scalable information processing with ultracold polar molecules in an electric field: A numerical investigation

    SciTech Connect

    Bomble, Laeetitia; Pellegrini, Philippe; Ghesquiere, Pierre; Desouter-Lecomte, Michele

    2010-12-15

    We numerically investigate the possibilities of driving quantum algorithms with laser pulses in a register of ultracold NaCs polar molecules in a static electric field. We focus on the possibilities of performing scalable logical operations by considering circuits that involve intermolecular gates (implemented on adjacent interacting molecules) to enable the transfer of information from one molecule to another during conditional laser-driven population inversions. We study the implementation of an arithmetic operation (the addition of 0 or 1 on a binary digit and a carry in) which requires population inversions only and the Deutsch-Jozsa algorithm which requires a control of the phases. Under typical experimental conditions, our simulations show that high-fidelity logical operations involving several qubits can be performed in a time scale of a few hundreds of microseconds, opening promising perspectives for the manipulation of a large number of qubits in these systems.

  1. Investigation of Efficiency in Applied Field MagnetoPlasmaDynamic Thrusters

    NASA Astrophysics Data System (ADS)

    Lev, Dan

    An experimental and theoretical investigation of the scaling of thrust efficiency with the operational parameters (J,B,m˙) of applied-field magnetoplasmadynamic thrusters (AF-MPDTs) is carried out to provide guidelines for scaling and controlling AF-MDPT performance. This investigation is based on characterization of the various power dissipation mechanisms in AF-MPDTs with a focus on the acceleration and anode sheath power components. A semi-empirical model is derived for the anode sheath voltage fall in AF-MPDTs and verified by comparison to experimental data on a 30~kW lithium-fed steady-state AF-MPDT obtained using a hot langmuir probe. It is found that the anode sheath voltage fall increases approximately linearly with current and applied magnetic field and is inversely proportional to mass flow rate. It is shown that, although the electrons in the anode sheath are unmagnetized the voltage fall is attributed to plasma density reduction at the sheath edge, which is a result of increased plasma pinching at higher applied magnetic field values. It is also concluded that increased thermionic emission from the anode surface leads to an increase in the anode sheath voltage fall; therefore anode material with a high work function is preferred. A thrust efficiency model is formulated by employing a thrust formula previously derived and verified for the same thruster, and composing expressions for the different voltage components in AF-MPDTs. It is demonstrated that the efficiency increases with applied magnetic field for all current and mass flow rate values, and the enhancement of the efficiency by the applied magnetic field is greater when the mass flow rate is reduced. It is shown that the efficiency-current curves have a decreasing-increasing behavior due to an interchange between the different thrust components, each of which dominates in a different current regime and thus affects the scalability of the acceleration power component with current. It is

  2. High-Field Magneto-Photoluminescence Spectroscopy of Highly-Aligned Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Shaver, J.; Kono, J.; Crooker, S. A.; Fagan, J. A.; Hobbie, E. K.

    2008-03-01

    We have investigated excitons in semiconducting single-walled carbon nanotubes (SWNTs) through low-temperature magneto-photoluminescence (PL) of highly-aligned SWNT films in magnetic fields (B) up to 55 T. The magnetic field was generated using the 60 T long pulse magnet powered by a 1.4 GVA motor-generator at the National High Magnetic Field Lab in Los Alamos, NM. Polyacrylic acid films containing DNA suspended CoMoCAT SWNTs were stretch-aligned, and the alignment factor was analyzed by polarized Raman spectroscopy^1. Utilizing two well-defined measurement geometries, SWNTs B and SWNTs B, we provide unambiguous evidence that the PL from excitons in SWNTs is sensitive only to the B-component parallel to the tube axis. We developed a theoretical model of one-dimensional magneto-excitons, based on recently-proposed exchange-split bright and dark exciton bands with Aharonov-Bohm-phase-dependent energies, masses, and oscillator strengths, which successfully reproduces our observations^2. 1. Fagan et al. Phys. Rev. Lett. 98, 147402 (2007) 2. Shaver et al. Nano Lett. 7, 1851 (2007)

  3. PIXELS: Using field-based learning to investigate students' concepts of pixels and sense of scale

    NASA Astrophysics Data System (ADS)

    Pope, A.; Tinigin, L.; Petcovic, H. L.; Ormand, C. J.; LaDue, N.

    2015-12-01

    Empirical work over the past decade supports the notion that a high level of spatial thinking skill is critical to success in the geosciences. Spatial thinking incorporates a host of sub-skills such as mentally rotating an object, imagining the inside of a 3D object based on outside patterns, unfolding a landscape, and disembedding critical patterns from background noise. In this study, we focus on sense of scale, which refers to how an individual quantified space, and is thought to develop through kinesthetic experiences. Remote sensing data are increasingly being used for wide-reaching and high impact research. A sense of scale is critical to many areas of the geosciences, including understanding and interpreting remotely sensed imagery. In this exploratory study, students (N=17) attending the Juneau Icefield Research Program participated in a 3-hour exercise designed to study how a field-based activity might impact their sense of scale and their conceptions of pixels in remotely sensed imagery. Prior to the activity, students had an introductory remote sensing lecture and completed the Sense of Scale inventory. Students walked and/or skied the perimeter of several pixel types, including a 1 m square (representing a WorldView sensor's pixel), a 30 m square (a Landsat pixel) and a 500 m square (a MODIS pixel). The group took reflectance measurements using a field radiometer as they physically traced out the pixel. The exercise was repeated in two different areas, one with homogenous reflectance, and another with heterogeneous reflectance. After the exercise, students again completed the Sense of Scale instrument and a demographic survey. This presentation will share the effects and efficacy of the field-based intervention to teach remote sensing concepts and to investigate potential relationships between students' concepts of pixels and sense of scale.

  4. Investigation on critical breakdown electric field of hot carbon dioxide for gas circuit breaker applications

    NASA Astrophysics Data System (ADS)

    Sun, Hao; Rong, Mingzhe; Wu, Yi; Chen, Zhexin; Yang, Fei; Murphy, Anthony B.; Zhang, Hantian

    2015-02-01

    Sulfur hexafluoride (SF6) gas is widely used in high-voltage circuit breakers, but due to its high global warming potential, substitutes are being sought. CO2 has been investigated as a candidate based on its arc interruption performance. The hot gas in the circuit breaker after current zero, with a complicated species composition caused by the dissociation and many other reactions, will lead to the electrical breakdown, which is one of the major concerns in assessing the arc interruption performance. Despite this, little research has been reported on the dielectric strength of hot CO2. In this paper, the dielectric properties of hot CO2 related to the dielectric recovery phase of the circuit breaker were investigated in the temperature range from 300 to 4000 K and in the pressure range from 0.01 to 1.0 MPa. Under the assumptions of local thermodynamic equilibrium (LTE) and local chemical equilibrium (LCE), the equilibrium compositions of hot CO2 were obtained based on Gibbs free energy minimization. The cross sections for interactions between electrons and the species are presented. The critical reduced electric field strength of CO2 was determined by balancing electron generation and loss. These were evaluated using the electron energy distribution function (EEDF) derived from the two-term Boltzmann transport equation. The result indicates that unlike SF6 or air, in hot CO2 the reduced critical electric field strength does not change monotonically with increasing heavy-particle temperature from 300 to 4000 K. CO2 has a superior dielectric strength to pure SF6 above 2500 K at 0.5 MPa, which means it has the potential to improve the interruption performance of the circuit breakers, while reducing the global warming effect. Good agreement was found with published experimental results and calculations for CO2 at room temperature, and with previous calculations for hot CO2.

  5. Investigation of normal shock inlets for highly maneuverable aircraft

    NASA Technical Reports Server (NTRS)

    Martin, A. W.

    1977-01-01

    Concepts are investigated for obtaining both low cowl drag and good inlet performance at high angles of attack. The effect of a canard on inlet performance for a kidney shaped inlet in each of two vertical locations is discussed along with a sharp lip two dimensional inlet on a canardless forebody.

  6. A Model for Investigating Predictive Validity at Highly Selective Institutions.

    ERIC Educational Resources Information Center

    Gross, Alan L.; And Others

    A statistical model for investigating predictive validity at highly selective institutions is described. When the selection ratio is small, one must typically deal with a data set containing relatively large amounts of missing data on both criterion and predictor variables. Standard statistical approaches are based on the strong assumption that…

  7. Investigating Safely: A Guide for High School Teachers

    ERIC Educational Resources Information Center

    Texley, Juliana; Kwan, Terry; Summers, John

    2004-01-01

    Just as high school science is more complex than it is at lower grade levels, so are the safety issues teachers face in their classes and labs. Reduce the risks to people and place with Investigating Safely, the third and most advanced and detailed volume in NSTA's unique series of safety guidebooks for science teachers. Some of the guides 11…

  8. High resolution, large dynamic range field map estimation

    PubMed Central

    Dagher, Joseph; Reese, Timothy; Bilgin, Ali

    2013-01-01

    Purpose We present a theory and a corresponding method to compute high resolution field maps over a large dynamic range. Theory and Methods We derive a closed-form expression for the error in the field map value when computed from two echoes. We formulate an optimization problem to choose three echo times which result in a pair of maximally distinct error distributions. We use standard field mapping sequences at the prescribed echo times. We then design a corresponding estimation algorithm which takes advantage of the optimized echo times to disambiguate the field offset value. Results We validate our method using high resolution images of a phantom at 7T. The resulting field maps demonstrate robust mapping over both a large dynamic range, and in low SNR regions. We also present high resolution offset maps in vivo using both, GRE and MEGE sequences. Even though the proposed echo time spacings are larger than the well known phase aliasing cutoff, the resulting field maps exhibit a large dynamic range without the use of phase unwrapping or spatial regularization techniques. Conclusion We demonstrate a novel 3-echo field map estimation method which overcomes the traditional noise-dynamic range trade-off. PMID:23401245

  9. MAGNETIC FIELDS IN HIGH-MASS INFRARED DARK CLOUDS

    SciTech Connect

    Pillai, T.; Kauffmann, J.; Tan, J. C.; Goldsmith, P. F.; Carey, S. J.; Menten, K. M.

    2015-01-20

    High-mass stars are cosmic engines known to dominate the energetics in the Milky Way and other galaxies. However, their formation is still not well understood. Massive, cold, dense clouds, often appearing as infrared dark clouds (IRDCs), are the nurseries of massive stars. No measurements of magnetic fields in IRDCs in a state prior to the onset of high-mass star formation (HMSF) have previously been available, and prevailing HMSF theories do not consider strong magnetic fields. Here, we report observations of magnetic fields in two of the most massive IRDCs in the Milky Way. We show that IRDCs G11.11–0.12 and G0.253+0.016 are strongly magnetized and that the strong magnetic field is as important as turbulence and gravity for HMSF. The main dense filament in G11.11–0.12 is perpendicular to the magnetic field, while the lower density filament merging onto the main filament is parallel to the magnetic field. The implied magnetic field is strong enough to suppress fragmentation sufficiently to allow HMSF. Other mechanisms reducing fragmentation, such as the entrapment of heating from young stars via high-mass surface densities, are not required to facilitate HMSF.

  10. Low-field versus high-field MRI in diagnosing breast disorders.

    PubMed

    Pääkkö, Eija; Reinikainen, Heli; Lindholm, Eija-Leena; Rissanen, Tarja

    2005-07-01

    We evaluated the performance of low-field MRI in breast disorders by comparing it with high-field MRI and biopsy results. Twenty-eight consecutive patients who were able to undergo two magnetic resonance examinations on following days were examined by high-field and low-field MRI. After T1-weighted sagittal images had been obtained a dynamic 3D axial study was performed followed by the acquisition of contrast-enhanced T1-weighted sagittal images. The images were analyzed separately by two radiologists paying attention to lesion morphology and enhancement kinetics. Six patients had problems in both breasts (34 breasts studied). The results were compared with biopsy results of 27 breasts. There were 16 malignant lesions, two fibroadenomas and nine other benign lesions. The inter-magnetic-resonance-scanner kappa value was 0.77 (substantial agreement), while the interobserver kappa value was 0.86 and 0.81 at low and high field, respectively (excellent agreement). The sensitivity was 100 and 100%, the specificity was 82 and 73% and the accuracy was 93 and 89% at low and high field, respectively. The mean lesion size was 2 cm and the smallest malignant lesion was 8 mm in diameter. Low-field MRI is a promising tool for breast imaging. Larger materials and smaller lesions are needed to evaluate its true sensitivity and specificity. PMID:15711841

  11. An experimental investigation of domain wall motion in polycrystalline Ni during high-rate compressive loading

    NASA Astrophysics Data System (ADS)

    Ghosh, Dipankar; Bah, Abubakarr; Carman, Gregory P.; Ravichandran, Guruswami

    2016-01-01

    This paper describes experimental data on a polycrystalline nickel subjected to compressive loads induced in a split Hopkinson pressure bar test. A perpendicular bias magnetic field with respect to the loading direction is used to orient the domains and a pick-up coil measures the magnetic response of the sample during loading. Utilizing this experimental configuration, this study investigated the coupled effects of the magnetic and mechanical fields on domain wall motion in a polycrystalline magnetostrictive material (Ni) during the high-rate elastic loading. The experimental measurements reveal that the magnitude of the stress-induced magnetization change is dependent upon bias magnetic field.

  12. Australian High Schools Use Audio-Tutorials in Field Biology

    ERIC Educational Resources Information Center

    Meyer, G. R.; Postlethwait, S. N.

    1970-01-01

    Describes a workshop program for biology teachers involving the preparation of audio-tutorial units designed to prepare high school students for independent study of field ecology. Outlines units prepared and discusses usefulness of similar units in high schools and elsewhere. (EB)

  13. High field CdS detector for infrared radiation

    NASA Technical Reports Server (NTRS)

    Tyagi, R. C.; Boer, K. W.; Hadley, H. C.; Robertson, J. B.

    1972-01-01

    New and highly sensitive method of detecting infrared irradiation makes possible solid state infrared detector which is more sensitive near room temperature than usual photoconductive low band gap semiconductor devices. Reconfiguration of high field domains in cadmium sulphide crystals provides basis for discovery.

  14. High-field small animal magnetic resonance oncology studies

    NASA Astrophysics Data System (ADS)

    Bokacheva, Louisa; Ackerstaff, Ellen; LeKaye, H. Carl; Zakian, Kristen; Koutcher, Jason A.

    2014-01-01

    This review focuses on the applications of high magnetic field magnetic resonance imaging (MRI) and spectroscopy (MRS) to cancer studies in small animals. High-field MRI can provide information about tumor physiology, the microenvironment, metabolism, vascularity and cellularity. Such studies are invaluable for understanding tumor growth and proliferation, response to treatment and drug development. The MR techniques reviewed here include 1H, 31P, chemical exchange saturation transfer imaging and hyperpolarized 13C MRS as well as diffusion-weighted, blood oxygen level dependent contrast imaging and dynamic contrast-enhanced MRI. These methods have been proven effective in animal studies and are highly relevant to human clinical studies.

  15. Enhanced trapped field performance of bulk high-temperature superconductors using split coil, pulsed field magnetization with an iron yoke

    NASA Astrophysics Data System (ADS)

    Ainslie, M. D.; Fujishiro, H.; Mochizuki, H.; Takahashi, K.; Shi, Y.-H.; Namburi, D. K.; Zou, J.; Zhou, D.; Dennis, A. R.; Cardwell, D. A.

    2016-07-01

    Investigating and predicting the magnetization of bulk superconducting materials and developing practical magnetizing techniques is crucial to using them as trapped field magnets in engineering applications. The pulsed field magnetization (PFM) technique is considered to be a compact, mobile and relative inexpensive way to magnetize bulk samples, requiring shorter magnetization times (on the order of milliseconds) and a smaller and less complicated magnetization fixture; however, the trapped field produced by PFM is generally much smaller than that of slower zero field cooling or field cooling techniques, particularly at lower operating temperatures. In this paper, the PFM of two, standard Ag-containing Gd–Ba–Cu–O samples is carried out using two types of magnetizing coils: (1) a solenoid coil, and (2) a split coil, both of which make use of an iron yoke to enhance the trapped magnetic field. It is shown that a significantly higher trapped field can be achieved using a split coil with an iron yoke, and in order to explain these how this arrangement works in detail, numerical simulations using a 2D axisymmetric finite element method based on the H -formulation are carried to qualitatively reproduce and analyze the magnetization process from both electromagnetic and thermal points of view. It is observed that after the pulse peak significantly less flux exits the bulk when the iron core is present, resulting in a higher peak trapped field, as well as more overall trapped flux, after the magnetization process is complete. The results have important implications for practical applications of bulk superconductors as such a split coil arrangement with an iron yoke could be incorporated into the design of a portable, high magnetic field source/magnet to enhance the available magnetic field or in an axial gap-type bulk superconducting electric machine, where iron can be incorporated into the stator windings to (1) improve the trapped field from the magnetization

  16. Experimental and theoretical investigation of high gradient acceleration

    SciTech Connect

    Wurtele, J.S.; Bekefi, G.; Chen, C.; Chen, S.C.; Temkin, R.J.

    1993-01-01

    This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-AC02-91-ER40648, Experimental and Theoretical Investigations of High Gradient Acceleration''. This grant supports three research tasks: Task A consists of the design, fabrication and testing of a 17GHz RF photocathode gun, which can produce 2ps electron pulses with up to 1nC of charge at 2MeV energy and at a 1OHz repetition rate. Task B supports the testing of high gradient acceleration at 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders.

  17. Multi-shot PROPELLER for high-field preclinical MRI

    PubMed Central

    Pandit, Prachi; Qi, Yi; Story, Jennifer; King, Kevin F.; Johnson, G. Allan

    2012-01-01

    With the development of numerous mouse models of cancer, there is a tremendous need for an appropriate imaging technique to study the disease evolution. High-field T2-weighted imaging using PROPELLER MRI meets this need. The 2-shot PROPELLER technique presented here, provides (a) high spatial resolution, (b) high contrast resolution, and (c) rapid and non-invasive imaging, which enables high-throughput, longitudinal studies in free-breathing mice. Unique data collection and reconstruction makes this method robust against motion artifacts. The 2-shot modification introduced here, retains more high-frequency information and provides higher SNR than conventional single-shot PROPELLER, making this sequence feasible at high-fields, where signal loss is rapid. Results are shown in a liver metastases model to demonstrate the utility of this technique in one of the more challenging regions of the mouse, which is the abdomen. PMID:20572138

  18. FRONTIER FIELDS: HIGH-REDSHIFT PREDICTIONS AND EARLY RESULTS

    SciTech Connect

    Coe, Dan; Bradley, Larry; Zitrin, Adi

    2015-02-20

    The Frontier Fields program is obtaining deep Hubble and Spitzer Space Telescope images of new ''blank'' fields and nearby fields gravitationally lensed by massive galaxy clusters. The Hubble images of the lensed fields are revealing nJy sources (AB mag > 31), the faintest galaxies yet observed. The full program will transform our understanding of galaxy evolution in the first 600 million years (z > 9). Previous programs have yielded a dozen or so z > 9 candidates, including perhaps fewer than expected in the Ultra Deep Field and more than expected in shallower Hubble images. In this paper, we present high-redshift (z > 6) number count predictions for the Frontier Fields and candidates in three of the first Hubble images. We show the full Frontier Fields program may yield up to ∼70 z > 9 candidates (∼6 per field). We base this estimate on an extrapolation of luminosity functions observed between 4 < z < 8 and gravitational lensing models submitted by the community. However, in the first two deep infrared Hubble images obtained to date, we find z ∼ 8 candidates but no strong candidates at z > 9. We defer quantitative analysis of the z > 9 deficit (including detection completeness estimates) to future work including additional data. At these redshifts, cosmic variance (field-to-field variation) is expected to be significant (greater than ±50%) and include clustering of early galaxies formed in overdensities. The full Frontier Fields program will significantly mitigate this uncertainty by observing six independent sightlines each with a lensing cluster and nearby blank field.

  19. [Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio]. Volume 5, Field Investigation report

    SciTech Connect

    Not Available

    1992-03-01

    An environmental investigation of ground water conditions has been undertaken at Wright-Patterson Air Force Base (WPAFB), Ohio to obtain data to assist in the evaluation of a potential removal action to prevent, to the extent practicable, migration of the contaminated ground water across Base boundaries. Field investigations were limited to the central section of the southwestern boundary of Area C and the Springfield Pike boundary of Area B. Further, the study was limited to a maximum depth of 150 feet below grade. Three primary activities of the field investigation were: (1) installation of 22 monitoring wells, (2) collection and analysis of ground water from 71 locations, (3) measurement of ground water elevations at 69 locations. Volatile organic compounds including trichloroethylene, perchloroethylene, and/or vinyl chloride were detected in concentrations exceeding Maximum Contaminant Levels (MCL) at three locations within the Area C investigation area. Ground water at the Springfield Pike boundary of Area B occurs in two primary units, separated by a thicker-than-expected clay layers. One well within Area B was determined to exceed the MCL for trichloroethylene.

  20. Microchip Electrophoresis at Elevated Temperatures and High Separation Field Strengths

    PubMed Central

    Mitra, Indranil; Marczak, Steven P.; Jacobson, Stephen C.

    2014-01-01

    We report free-solution microchip electrophoresis performed at elevated temperatures and high separation field strengths. We used microfluidic devices with 11-cm long separation channels to conduct separations at temperatures between 22 (ambient) and 45 °C and field strengths from 100 to 1000 V/cm. To evaluate separation performance, N-glycans were used as a model system and labeled with 8-aminopyrene-1,3,6-trisulfonic acid to impart charge for electrophoresis and render them fluorescent. Typically, increased diffusivity at higher temperatures leads to increased axial dispersion and poor separation performance; however, we demonstrate that sufficiently high separation field strengths can be used to offset the impact of increased diffusivity in order to maintain separation efficiency. Efficiencies for these free-solution separations are the same at temperatures of 25, 35, and 45 °C with separation field strengths ≥500 V/cm. PMID:24114979

  1. Proximity superconductivity in ballistic graphene at high magnetic fields

    NASA Astrophysics Data System (ADS)

    Prance, J. R.; Ben Shalom, M.; Zhu, M. J.; Fal'Ko, V. I.; Mishchenko, A.; Kretinin, A. V.; Novoselov, K. S.; Woods, C. R.; Watanabe, K.; Taniguchi, T.; Geim, A. K.

    We present measurements of the superconducting proximity effect in graphene-based Josephson junctions with a mean free path of several microns, which exceeds the junctions' length. The junctions exhibit low contact resistance and large supercurrents. We observe Fabry-Pérot oscillations in the normal-state resistance and the critical current of the junctions. The proximity effect is mostly suppressed in magnetic fields of <10 mT showing the conventional Fraunhofer interference pattern; however, unexpectedly, a weak proximity effect survives in magnetic fields as high as 1 T. Superconducting states randomly appear and disappear as a function of field and carrier concentration, and each exhibits a supercurrent carrying capacity close to the universal limit of e Δ/h where Δ is the superconducting gap of the contacts. We attribute the high-field supercurrent to mesoscopic Andreev states that persist near graphene edges. Our work reveals new proximity regimes that can be controlled by quantum confinement and cyclotron motion.

  2. Deuterium NMR investigations of field-induced director alignment in nematic liquid crystals.

    PubMed

    Sugimura, Akihiko; Luckhurst, Geoffrey R

    2016-05-01

    There have been many investigations of the alignment of nematic liquid crystals by either a magnetic and/or an electric field. The basic features of the important hydrodynamic processes for low molar mass nematics have been characterized for the systems in their equilibrium and non-equilibrium states. These have been created using electric and magnetic fields to align the director and deuterium nuclear magnetic resonance ((2)H NMR) spectroscopy has been used to explore this alignment. Theoretical models based on continuum theory have been developed to complement the experiments and found to describe successfully the static and the dynamic phenomena observed. Such macroscopic behaviour has been investigated with (2)H NMR spectroscopy, in which an electric field in addition to the magnetic field of the spectrometer is used to rotate the director and produce a non-equilibrium state. This powerful technique has proved to be especially valuable for the investigation of nematic liquid crystals. Since the quadrupolar splitting for deuterons observed in the liquid crystal phase is determined by the angle between the director and the magnetic field, time-resolved and time-averaged (2)H NMR spectroscopies can be employed to investigate the dynamic director alignment process in a thin nematic film following the application or removal of an electric field. In this article, we describe some seminal studies to illustrate the field-induced static and dynamic director alignment for low molar mass nematics. PMID:27247284

  3. The Effect of High Voltage, High Frequency Pulsed Electric Field on Slain Ovine Cortical Bone

    PubMed Central

    Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

    2014-01-01

    High power, high frequency pulsed electric fields known as pulsed power (PP) has been applied recently in biology and medicine. However, little attention has been paid to investigate the application of pulse power in musculoskeletal system and its possible effect on functional behavior and biomechanical properties of bone tissue. This paper presents the first research investigating whether or not PP can be applied safely on bone tissue as a stimuli and what will be the possible effect of these signals on the characteristics of cortical bone by comparing the mechanical properties of this type of bone pre and post expose to PP and in comparison with the control samples. A positive buck-boost converter was applied to generate adjustable high voltage, high frequency pulses (up to 500 V and 10 kHz). The functional behavior of bone in response to pulse power excitation was elucidated by applying compressive loading until failure. The stiffness, failure stress (strength) and the total fracture energy (bone toughness) were determined as a measure of the main bone characteristics. Furthermore, an ultrasonic technique was applied to determine and comprise bone elasticity before and after pulse power stimulation. The elastic property of cortical bone samples appeared to remain unchanged following exposure to pulse power excitation for all three orthogonal directions obtained from ultrasonic technique and similarly from the compression test. Nevertheless, the compressive strength and toughness of bone samples were increased when they were exposed to 66 h of high power pulsed electromagnetic field compared to the control samples. As the toughness and the strength of the cortical bone tissue are directly associated with the quality and integrity of the collagen matrix whereas its stiffness is primarily related to bone mineral content these overall results may address that although, the pulse power stimulation can influence the arrangement or the quality of the collagen network

  4. The effect of high voltage, high frequency pulsed electric field on slain ovine cortical bone.

    PubMed

    Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

    2014-04-01

    High power, high frequency pulsed electric fields known as pulsed power (PP) has been applied recently in biology and medicine. However, little attention has been paid to investigate the application of pulse power in musculoskeletal system and its possible effect on functional behavior and biomechanical properties of bone tissue. This paper presents the first research investigating whether or not PP can be applied safely on bone tissue as a stimuli and what will be the possible effect of these signals on the characteristics of cortical bone by comparing the mechanical properties of this type of bone pre and post expose to PP and in comparison with the control samples. A positive buck-boost converter was applied to generate adjustable high voltage, high frequency pulses (up to 500 V and 10 kHz). The functional behavior of bone in response to pulse power excitation was elucidated by applying compressive loading until failure. The stiffness, failure stress (strength) and the total fracture energy (bone toughness) were determined as a measure of the main bone characteristics. Furthermore, an ultrasonic technique was applied to determine and comprise bone elasticity before and after pulse power stimulation. The elastic property of cortical bone samples appeared to remain unchanged following exposure to pulse power excitation for all three orthogonal directions obtained from ultrasonic technique and similarly from the compression test. Nevertheless, the compressive strength and toughness of bone samples were increased when they were exposed to 66 h of high power pulsed electromagnetic field compared to the control samples. As the toughness and the strength of the cortical bone tissue are directly associated with the quality and integrity of the collagen matrix whereas its stiffness is primarily related to bone mineral content these overall results may address that although, the pulse power stimulation can influence the arrangement or the quality of the collagen network

  5. The design of a large aperture high field dipole

    SciTech Connect

    Harfoush, F.; Harrison, M.; Kerby, J.; Koepke, K.; Mantsch, P.; Nicol, T.; Riddiford, A.; Theilacker, J.

    1989-12-01

    The impetus for this design report originated in the Snowmass 88 meeting where the subject of higher energies within the constraints of the existing Tevatron tunnel enclosure was investigated. It was determined that beam transport to the fixed target experimental areas was possible up to an energy of {approximately}1.5 Tev. Collider operation was feasible at somewhat higher energies (1.8 Tev), primarily limited by the ability to design a single turn beam abort system within the constraints of the straight section length. A new accelerator in the existing tunnel would, of necessity, have a similar though not identical lattice and straight section layout to the present Tevatron. Thus when issues arose in the magnet design requiring input from the accelerator standpoint we have assumed a Tevatron like machine. The possibility of using these high field magnets as elements in the existing Tevatron to create new warm space,' for another Interaction Region for example, also emphasizes compatibility with the present machine. 16 refs., 62 figs., 23 tabs.

  6. Investigation of a delta-wing fighter model flow field at transonic speeds

    NASA Technical Reports Server (NTRS)

    Bare, E. Ann; Reubush, David E.; Haddad, Raymond; Hathaway, Ross W.; Compton, Mike

    1987-01-01

    The paper reports a flow-field investigation on a 7.52-percent scale model of an advanced fighter aircraft design conducted in the NASA-Langley 16-ft Transonic Tunnel. The effects of free-stream Mach number, angle-of-attack, angle of sideslip, and various vortex control devices on the local flow values were studied. The model was tested at Mach numbers of 0.6, 0.9, and 1.2 and the angles of sideslip of 0 and +/- 5 deg; the model angle-of-attack was varied from -4 to 30 deg. Results are presented in terms of contour plots of local total pressure recovery. The dominant influence on the over-wing flow field was found to be the wing leading-edge vortex which first appears in the survey region at an angle-of-attack of 8 deg and increases in strength and influence with increasing angle-of-attack, finally dominating the entire survey region at very high angles-of-attack.

  7. High-energy electroproduction in an atomic field

    NASA Astrophysics Data System (ADS)

    Krachkov, P. A.; Milstein, A. I.

    2016-06-01

    The differential cross section of high-energy electroproduction in the electric field of heavy atoms is derived. The results are obtained with the exact account for the atomic field. We use the quasiclassical approximation to the wave functions in the external field. For heavy atoms, the Coulomb corrections substantially modify the differential cross section as compared with the Born result. They lead to the azimuth asymmetry in the differential cross section for the polarized incoming electron. The Coulomb corrections to the total cross section are obtained in the leading logarithmic approximation.

  8. Sharpening of field emitter tips using high-energy ions

    DOEpatents

    Musket, Ronald G.

    1999-11-30

    A process for sharpening arrays of field emitter tips of field emission cathodes, such as found in field-emission, flat-panel video displays. The process uses sputtering by high-energy (more than 30 keV) ions incident along or near the longitudinal axis of the field emitter to sharpen the emitter with a taper from the tip or top of the emitter down to the shank of the emitter. The process is particularly applicable to sharpening tips of emitters having cylindrical or similar (e.g., pyramidal) symmetry. The process will sharpen tips down to radii of less than 12 nm with an included angle of about 20 degrees. Because the ions are incident along or near the longitudinal axis of each emitter, the tips of gated arrays can be sharpened by high-energy ion beams rastered over the arrays using standard ion implantation equipment. While the process is particularly applicable for sharpening of arrays of field emitters in field-emission flat-panel displays, it can be effectively utilized in the fabrication of other vacuum microelectronic devices that rely on field emission of electrons.

  9. Design considerations for a large aperture high field superconducting dipole

    SciTech Connect

    Harfoush, F.; Ankenbrandt, C.; Harrison, M.; Kerby, J.; Koepke, K.; Mantsch, P.; Nicol, T.; Riddiford, A.; Theilacker, J.

    1989-03-01

    The final phase of the Fermilab upgrade proposal calls for a new ring of superconducting magnets to be placed in the existing Main Accelerator tunnel. The goal of this design study is to specify a high field dipole (HFD) that is capable of supporting fixed target operation (ramping, resonant extraction) at a field of 6.6T (1.5 Tev) and colliding beam physics at 8.0T (1.8 Tev). The magnetic field quality at high field is set by the large amplitude orbits associated with resonant extraction. The field quality must therefore be at least as good as the existing Tevatron magnets which fulfill these criteria. The high fields and large aperture of this magnet result in large forces on the coil and collar assemblies. Therefore, the cold mass design must be able to sustain these forces while providing sufficient cooling to the coils during 4.2 K fixed target operation, and a minimum heat load during 1.8 K collider operation. The design work is still in progress but a cosine-theta, cold-iron dipole with a 70mm inner diameter coil has been tentatively adopted. This report presents details on the conductor and cable parameters, coil cross-section, projected manufacturing tolerances, iron yoke design, and cold mass assembly. 4 refs., 5 figs., 1 tab.

  10. Wavelength scaling of efficient high-order harmonic generation by two-color infrared laser fields

    SciTech Connect

    Lan Pengfei; Takahashi, Eiji J.; Midorikawa, Katsumi

    2010-06-15

    We theoretically investigate and demonstrate a better wavelength scaling of harmonic yield in a two-color infrared field. By mixing a Ti:sapphire assistant field with the infrared driving field, we show that high harmonic generation is enhanced and the harmonic yield scales as {lambda}{sup -3}-{lambda}{sup -4} in the plateau region, which falls more slowly as the increase of the driving laser wavelength {lambda} compared with {lambda}{sup -5}-{lambda}{sup -6} in a one-color infrared field.

  11. Investigation of CO2 induced biogeochemical reactions and active microorganisms of two German gas fields

    NASA Astrophysics Data System (ADS)

    Hoth, N.; Kassahun, A.; Seifert, J.; Krüger, M.; Bretschneider, H.; Gniese, C.; Frerichs, J.; Simon, A.; Simon, E.; Muschalle, T.

    2009-04-01

    The BMBF-Geotechnologien project "RECOBIO 2" continues the investigation of the long-term biogeochemical transformation of stored CO2. In addition to the Upper Carboniferous gas reservoir Schneeren (Westphalian C) the almost depleted Altmark gas field (Permian - Upper Rotliegend) is also investigated. Both sandstone reservoirs belong to the North German Basin and are operated by the GDF SUEZ E&P Germany (GDF SUEZ). The reservoirs differ in depth, initial and current fluid pressure as well as reservoir temperature, which is a biogeochemical important parameter. While the uplifted horst structure of Schneeren (approx. depth 2700 m) has a temperature level of 80 - 90 °C, the Altmark gas field (approx. depth 3300 m) shows temperatures around 120 °C. The Altmark site is known to be favourable for underground CO2-storage by enhanced gas recovery (EGR). This EGR process is operated by GDF SUEZ at the small and hydraulic isolated reservoir block "Altensalzwedel". This pilot test is accompanied by the scientific large-scale project CLEAN. In addition the RECOBIO2 project characterises the biogeochemical situation of the both large reservoir blocks of the Altmark gas field - „Salzwedel/ Peckensen" and „Heidberg/ Mellin". The produced formation waters of these reservoir blocks were sampled on different wellheads. The redox potentials are partly very low (Eh up to -300 mV) with slightly acidic pH-values (5,5 to 6). The high saline and (nearly) sulphate free formation waters of Na/Ca-Cl type have very high loads of Zn, Pb, Hg and As. In combination to the analysed DOC levels the talk discusses the importance of metal organic complexes. Also results of fluid geochemical calculations will be presented. Furthermore the diversity of bacteria and archaea of the formation waters as well as the potentials of CH4-, CO2-formation and sulphate reduction will be shown. Therefore the cultivation experiments were carried out with different substrates (H2/CO2, acetate, methanol). It

  12. High field CdS detector for infrared radiation

    NASA Technical Reports Server (NTRS)

    Tyagi, R. C.; Robertson, J. B.; Boer, K. W.; Hadley, H. C., Jr. (Inventor)

    1974-01-01

    An infrared radiation detector including a cadmium sulfide platelet having a cathode formed on one of its ends and an anode formed on its other end is presented. The platelet is suitably doped such that stationary high-field domains are formed adjacent the cathode when based in the negative differential conductivity region. A negative potential is applied to the cathode such that a high-field domain is formed adjacent to the cathode. A potential measuring probe is located between the cathode and the anode at the edge of the high-field domain and means are provided for measuring the potential at the probe whereby this measurement is indicative of the infrared radiation striking the platelet.

  13. An investigation into the vector ellipticity of extremely low frequency magnetic fields from appliances in UK homes.

    PubMed

    Ainsbury, Elizabeth A; Conein, Emma; Henshaw, Denis L

    2005-07-01

    Elliptically polarized magnetic fields induce higher currents in the body compared with their plane polarized counterparts. This investigation examines the degree of vector ellipticity of extremely low frequency magnetic fields (ELF-MFs) in the home, with regard to the adverse health effects reportedly associated with ELF-MFs, for instance childhood leukaemia. Tri-axial measurements of the magnitude and phase of the 0-3000 Hz magnetic fields, produced by 226 domestic mains-fed appliances of 32 different types, were carried out in 16 homes in Worcestershire in the summer of 2004. Magnetic field strengths were low, with average (RMS) values of 0.03 +/- 0.02 microT across all residences. In contrast, background field ellipticities were high, on average 47 +/- 11%. Microwave and electric ovens produced the highest ellipticities: mean respective values of 21 +/- 21% and 21 +/- 17% were observed 20 cm away from these appliances. There was a negative correlation between field strength and field polarization, which we attribute to the higher relative field contribution close to each individual (single-phase) appliance. The measurements demonstrate that domestic magnetic fields are extremely complex and cannot simply be characterized by traditional measurements such as time-weighted average or peak exposure levels. We conclude that ellipticity should become a relevant metric for future epidemiological studies of health and ELF-MF exposure. PMID:15972990

  14. An investigation into the vector ellipticity of extremely low frequency magnetic fields from appliances in UK homes

    NASA Astrophysics Data System (ADS)

    Ainsbury, Elizabeth A.; Conein, Emma; Henshaw, Denis L.

    2005-07-01

    Elliptically polarized magnetic fields induce higher currents in the body compared with their plane polarized counterparts. This investigation examines the degree of vector ellipticity of extremely low frequency magnetic fields (ELF-MFs) in the home, with regard to the adverse health effects reportedly associated with ELF-MFs, for instance childhood leukaemia. Tri-axial measurements of the magnitude and phase of the 0-3000 Hz magnetic fields, produced by 226 domestic mains-fed appliances of 32 different types, were carried out in 16 homes in Worcestershire in the summer of 2004. Magnetic field strengths were low, with average (RMS) values of 0.03 ± 0.02 µT across all residences. In contrast, background field ellipticities were high, on average 47 ± 11%. Microwave and electric ovens produced the highest ellipticities: mean respective values of 21 ± 21% and 21 ± 17% were observed 20 cm away from these appliances. There was a negative correlation between field strength and field polarization, which we attribute to the higher relative field contribution close to each individual (single-phase) appliance. The measurements demonstrate that domestic magnetic fields are extremely complex and cannot simply be characterized by traditional measurements such as time-weighted average or peak exposure levels. We conclude that ellipticity should become a relevant metric for future epidemiological studies of health and ELF-MF exposure. This work is supported by the charity CHILDREN with LEUKAEMIA, registered charity number 298405.

  15. Electromechanical analysis of tapered piezoelectric bimorph at high electric field

    NASA Astrophysics Data System (ADS)

    Chattaraj, Nilanjan; Ganguli, Ranjan

    2015-04-01

    Piezoelectric bimorph laminar actuator of tapered width exhibits better performance for out-of-plane deflection compared to the rectangular surface area, while consuming equal surface area. This paper contains electromechanical analysis and modeling of a tapered width piezoelectric bimorph laminar actuator at high electric field in static state. The analysis is based on the second order constitutive equations of piezoelectric material, assuming small strain and large electric field to capture its behavior at high electric field. Analytical expressions are developed for block force, output strain energy, output energy density, input electrical energy, capacitance and energy efficiency at high electric field. The analytical expressions show that for fixed length, thickness, and surface area of the actuator, how the block force and output strain energy gets improved in a tapered surface actuator compared to a rectangular surface. Constant thickness, constant length and constant surface area of the actuator ensure constant mass, and constant electrical capacitance. We consider high electric field in both series and parallel electrical connection for the analysis. Part of the analytical results is validated with the experimental results, which are reported in earlier literature.

  16. Sources and Radiation Patterns of Volcano-Acoustic Signals Investigated with Field-Scale Chemical Explosions

    NASA Astrophysics Data System (ADS)

    Bowman, D. C.; Lees, J. M.; Taddeucci, J.; Graettinger, A. H.; Sonder, I.; Valentine, G.

    2014-12-01

    We investigate the processes that give rise to complex acoustic signals during volcanic blasts by monitoring buried chemical explosions with infrasound and audio range microphones, strong motion sensors, and high speed imagery. Acoustic waveforms vary with scaled depth of burial (SDOB, units in meters per cube root of joules), ranging from high amplitude, impulsive, gas expansion dominated signals at low SDOB to low amplitude, longer duration, ground motion dominated signals at high SDOB. Typically, the sudden upward acceleration of the substrate above the blast produces the first acoustic arrival, followed by a second pulse due to the eruption of pressurized gas at the surface. Occasionally, a third overpressure occurs when displaced material decelerates upon impact with the ground. The transition between ground motion dominated and gas release dominated acoustics ranges between 0.0038-0.0018 SDOB, respectively. For example, one explosion registering an SDOB=0.0031 produced two overpressure pulses of approximately equal amplitude, one due to ground motion, the other to gas release. Recorded volcano infrasound has also identified distinct ground motion and gas release components during explosions at Sakurajima, Santiaguito, and Karymsky volcanoes. Our results indicate that infrasound records may provide a proxy for the depth and energy of these explosions. Furthermore, while magma fragmentation models indicate the possibility of several explosions during a single vulcanian eruption (Alidibirov, Bull Volc., 1994), our results suggest that a single explosion can also produce complex acoustic signals. Thus acoustic records alone cannot be used to distinguish between single explosions and multiple closely-spaced blasts at volcanoes. Results from a series of lateral blasts during the 2014 field experiment further indicates whether vent geometry can produce directional acoustic radiation patterns like those observed at Tungarahua volcano (Kim et al., GJI, 2012). Beside

  17. A phase-field investigation of domain structures in ferroelectric bismuth ferrite thin films

    NASA Astrophysics Data System (ADS)

    Winchester, Benjamin

    The ferroelectric domain structure of multiferroic BiFeO3 thin films are strongly affected by the electrical boundary conditions. We employ a Ginzburg-Landau- Devonshire phase-field model to investigate the effects of the electrical boundary conditions on domain structure in BiFeO3 thin films. We examine the domain structure under short-circuit and under open-circuit boundary conditions with varying levels of compensation. As the degree of compensation changes, we find a smooth transition between the two types of domain structure. In the open-circuit case, we note small triangular nanodomains at the surface/wall interfaces that may be useful in nanoelectronic applications. The ferroelectric domain structures of epitaxial BiFeO3 thin films on miscut substrates were studied using a phase-field model. The effects of substrate vicinality towards are considered by assuming charge-compensated surface and film/substrate interface. The predicted domain structures show remarkable agreement with existing experimental observations, including domain wall orientations and local topological domain configurations. The roles of elastic, electric, and gradient energies on the domain structures were analyzed. It is shown that the substrate strain anisotropy due to the miscut largely determines the domain variant selection and domain configurations. We employ phase-field modeling to explore the elastic properties of artificiallycreated 1-D domain walls in (001)p-oriented BiFeO3 thin films. The walls are composed of a junction of the four polarization variants, all with the same out-of-plane polarization: a "vortex" is comprised of polarization variants rotating around the junction, and an "anti-vortex" is comprised of two polarization variants pointing towards the junction and two pointing away. It was found that these junctions exhibit peculiarly high electroelastic fields induced by the neighboring ferroelastic/ferroelectric domains. These fields may contribute to the segregation

  18. Development and application of color schlieren technique for investigation of three-dimensional concentration field

    NASA Astrophysics Data System (ADS)

    Srivastava, Atul

    2013-11-01

    The present work describes the development and application of rainbow schlieren deflectometry technique for the investigation of the three-dimensional concentration field around a crystal growing from its aqueous solution. The imaging technique employs a diverging beam of light to record the projection data of the concentration field. In contrast to the conventional schlieren methods, the present system makes use of a microscopic objective lens to act as the de-collimating lens for focusing the light beam onto the color filter to get the desired schlieren effect. In order to record the projection data of the concentration field from different view angles for tomographic reconstruction, the experiments are conducted in an octagonal growth cell. Detailed quantitative analysis of the schlieren images has then been carried out for each view angle to determine the path-integrated concentration distribution. Principles of tomography have been employed for the reconstruction of concentration field at select horizontal planes above the growing crystal. Results have been presented in the form of rainbow schlieren images of the convective field, path-averaged solute concentration distribution around the growing for each view angle and local concentration distribution at select horizontal planes above the crystal top surface. Recorded color schlieren images have been compared with those of the conventional monochrome schlieren and interferometric techniques for the same experimental conditions. The extent of color re-distribution as seen from the recorded rainbow schlieren images correlate well with the bright intensity regions of monochrome schlieren images and the extent of fringe deformation in the interferometric images. The comparison has been performed for a small as well as a comparatively larger-sized crystal. For small sized-crystal, the observed color redistribution is seen to be weak and restricted to the crystal vicinity only whereas the color changes are more

  19. Investigation of the plastic fracture of high strength steels

    NASA Technical Reports Server (NTRS)

    Cox, T. B.; Low, J. R., Jr.

    1972-01-01

    An investigation of the plastic fracture process to improve tensile strength in high strength steels is presented. Two generic types of steels are considered: a quenched and tempered grade and a maraging grade, in order to compare two different matrix microstructures. Each type of steel was studied in commercial grade purity and in special melted high purity form, low in residual and impurity elements. The specific alloys dealt with include AISI 4340 and 18 Ni, 200 grade maraging steel, both heat treated to the same yield strength level of approximately 200 ksi.

  20. Technology transfer opportunities: new development: computerized field manual provides valuable resource for hydrologic investigations

    USGS Publications Warehouse

    Chapel, Paul

    1996-01-01

    The U.S. Geological Survey (USGS) is known throughout the world for conducting quality scientific investigation is hydrologic environments. Proper and consistent field techniques have been an integral part of this good research. Over the past few decades, the USGS has developed and published detailed, standard protocols for conducting studies in most aspects of the hydrologic environment. These protocols have been published in a number of diverse documents. The wealth of information contained in these diverse documents can benefit other scientists in industry, government, and academia that are involved in conducting hydrologic studies. Scientists at the USGS have brought together many of the most important of the field protocols in a user-friendly, graphical-interfaced field manual that will be useful in both the field and in the office. This electronic field manual can assist hydrologists and other scientists in conducting and documenting their field activities in a manner that is recognized standard throughout the hydrologic community.

  1. Investigation of electric field distribution on FAC-IR-300 ionization chamber

    NASA Astrophysics Data System (ADS)

    Mohammadi, S. M.; Tavakoli-Anbaran, H.; Zeinali, H. Z.

    2016-07-01

    One of the important parameters for establishing charge particle equilibrium (CPE) conditions of free-air ionization chamber is an electric field distribution. In this paper, electric field distribution inside the ionization chamber was investigated by finite element method. For this purpose, the effects of adding guard plate and guard strips on the electric field distribution in the ionization chamber were studied. it is necessary to apply a lead box around the ionization chamber body to avoid of scattered radiation effects on the ionization chamber operation, but the lead box changes the electric field distribution. In the following, the effect of lead box on the electric field distribution was studied. Finally, electric field distribution factor (kfield) was calculated by the simulation. The results of the simulation showed that presence of the guard plate and guard strips, and applying a suitable potential to lead box, a convergence of kfield to 1 was achieved.

  2. High-Efficiency Absorber for Damping the Transverse Wake Fields

    SciTech Connect

    Novokhatski, A.; Seeman, J.; Weathersby, S.; /SLAC

    2007-02-28

    Transverse wake fields generated by intense beams may propagate long distances in the vacuum chamber and dissipate power in different shielded elements such as bellows, vacuum valves or vacuum pumps. Induced heating in these elements may be high enough to deteriorate vacuum conditions. We have developed a broadband water-cooled bellows-absorber to capture and damp these harmful transverse fields without impacting the longitudinal beam impedance. Experimental results at the PEP-II SLAC B-factory demonstrate high efficiency of this device. This absorber may be useful in other machines like synchrotron light sources or International Linear Collider.

  3. Study of HTS Wires at High Magnetic Fields

    SciTech Connect

    Turrioni, D.; Barzi, E.; Lamm, M.J.; Yamada, R.; Zlobin, A.V.; Kikuchi, A.; /Fermilab

    2009-01-01

    Fermilab is working on the development of high field magnet systems for ionization cooling of muon beams. The use of high temperature superconducting (HTS) materials is being considered for these magnets using Helium refrigeration. Critical current (I{sub c}) measurements of HTS conductors were performed at FNAL and at NIMS up to 28 T under magnetic fields at zero to 90 degree with respect to the sample face. A description of the test setups and results on a BSCCO-2223 tape and second generation (2G) coated conductors are presented.

  4. Investigation and Preparation of High Impact Polystyrene Nanocomposites

    NASA Astrophysics Data System (ADS)

    Khoshniyat, A. R.; Aalaie, J.; Rahmatpour, A.; Khanbabaie, G.

    2010-03-01

    A series of polymer—organoclay nanocomposite materials consisting of polystyrene (PS) and high impact polystyrene (HIPS), layered montmorillonite organo clay (MMT) were prepared by dispersing nanophase in the organic PS matrix via in situ thermal polymerization. The nanocomposite effects on the chemical resistance and mechanical properties modification of PS and HIPS were investigated and characterized by XRD, SEM, chemical and mechanical testing. The results show That HIPS/organo clay nanocomposites have the best chemical resistant.

  5. Limited field investigation report for the 100-KR-4 Operable Unit

    SciTech Connect

    Not Available

    1994-07-01

    This limited field investigation (LFI) was conducted to optimize the use of interim remedial measures (IRM) for expediting clean up while maintaining a technically sound and cost-effective program. The 100-KR-4 Operable Unit is one of four operable units associated with the 100 K Area. Operable units KR-1, KR-2 and KR-3 address contaminant sources while 100-KR-4 addresses contamination present in the underlying groundwater. The IRM decision process for groundwater operable units is based on three aspects: (1) Is the concentration greater than Hanford background? (2) Does the concentration present a medium or high human-health risk? (3) Does the concentration exceed an ecologically based applicable, relevant and appropriate requirements (ARAR) or present an environmental hazard quotient > I? The primary methods of investigation used during this LFI were the installation of monitoring wells and sampling of groundwater. The samples collected from the groundwater and soils were submitted for laboratory analysis. Boreholes were surveyed for radiological contamination using downhole geophysical techniques to further delineate the location and degree of contamination. All soil samples were screened to ascertain the presence of volatile organic compounds and radionuclides. Analytical data were subjected to validation; all first round and a minimum of 10% of subsequent round data were validated.

  6. Investigation of the Rocket Induced Flow Field in a Rectangular Duct

    NASA Technical Reports Server (NTRS)

    Landrum, D. Brian; Lambert, James; Thames, Mignon; Hawk, Clark

    1999-01-01

    Rocket-Based Combined Cycle (RBCC) concepts attempt to improve the performance of launch vehicles at all points in the launch trajectory and make highly reusable launch vehicles a reality. The Aerojet Strutjet RBCC concept consists of a variable geometry duct with internal, vertical struts that functions in ducted rocket, ramjet, scramjet, and pure rocket modes. These struts have rocket and turbine exhaust nozzles imbedded within them. The rocket flows create an ejector effect with the ingested air at subsonic flight velocities. In ramjet and scramjet modes, the fuel rich nozzle flows react with the ingested air producing an afterburner effect. Under a NASA Marshall Space Flight Center contract, the UAH Propulsion Research Center (PRC) has designed and built a Strutjet simulation facility. A scale model of a single strut has been built and is undergoing cold-flow testing to investigate the mixing of the rocket and turbine exhausts with the ingested air. A complementary experimental program is also underway to examine the induced flow-field generated by rocket nozzles confined in a rectangular duct. Characterizing the induced flow behavior is critical to understanding and optimizing the performance of future Strutjet-based RBCC propulsion systems. The proposed paper will present results from the rocket induced flow investigation.

  7. New high homogeneity 55 T pulsed magnet for high field NMR

    NASA Astrophysics Data System (ADS)

    Orlova, A.; Frings, P.; Suleiman, M.; Rikken, G. L. J. A.

    2016-07-01

    Pulsed magnets can produce magnetic fields largely exceeding those achieved with resistive or even hybrid magnets. This kind of magnet is indispensable in studies of field-induced phenomena which occur only in high magnetic field. A new high homogeneous pulsed magnet capable of producing field up to 55 T and specially designed for NMR experiments was built and tested. Experimentally observed homogeneity of magnetic field in central part of the magnet is 10 ppm over a sample volume of 2-3 mm3 at 12 T and 30 ppm at 47 T, which are the best values ever reported for a pulsed magnet. Reasons which affect the field profile and reduce homogeneity at high field are discussed.

  8. New high homogeneity 55T pulsed magnet for high field NMR.

    PubMed

    Orlova, A; Frings, P; Suleiman, M; Rikken, G L J A

    2016-07-01

    Pulsed magnets can produce magnetic fields largely exceeding those achieved with resistive or even hybrid magnets. This kind of magnet is indispensable in studies of field-induced phenomena which occur only in high magnetic field. A new high homogeneous pulsed magnet capable of producing field up to 55T and specially designed for NMR experiments was built and tested. Experimentally observed homogeneity of magnetic field in central part of the magnet is 10ppm over a sample volume of 2-3mm(3) at 12T and 30ppm at 47T, which are the best values ever reported for a pulsed magnet. Reasons which affect the field profile and reduce homogeneity at high field are discussed. PMID:27179456

  9. Two-field high-scale inflation in a sub-Planckian region of field space

    SciTech Connect

    Berg, Marcus; Pajer, Enrico; Sjoers, Stefan

    2010-05-15

    We present a simple two-field model of inflation and show how to embed it in string theory as a straightforward generalization of axion monodromy models. Phenomenologically, the predictions are equivalent to those of chaotic inflation, and, in particular, include observably large tensor modes. The whole high-scale large-field inflationary dynamics takes place within a region of field space that is parametrically sub-Planckian in diameter, hence improving our ability to control quantum corrections and achieve slow-roll inflation.

  10. High-latitude field-aligned current sources and induced electric fields

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.

    1979-01-01

    Using a simple, planar model of the high latitude ionosphere with an enhanced conductivity auroral ring, the electric potential is computed for a pair of field-aligned current sheets inferred from observations. The relationship of various characteristics of the electric potential pattern to features of the field-aligned current distribution are elucidated in the context of a generalized field-aligned current Fourier analysis. On the basis of the analysis and observations to date, it is concluded that boundary layer dynamo action is the prevalent mechanism in the solar wind/magnetosphere/ionosphere interaction.

  11. Field-effect transistor having a superlattice channel and high carrier velocities at high applied fields

    DOEpatents

    Chaffin, R.J.; Dawson, L.R.; Fritz, I.J.; Osbourn, G.C.; Zipperian, T.E.

    1987-06-08

    A field effect transistor comprises a semiconductor having a source, a drain, a channel and a gate in operational relationship. The semiconductor is a strained layer superlattice comprising alternating quantum well and barrier layers, the quantum well layers and barrier layers being selected from the group of layer pairs consisting of InGaAs/AlGaAs, InAs/InAlGaAs, and InAs/InAlAsP. The layer thicknesses of the quantum well and barrier layers are sufficiently thin that the alternating layers constitute a superlattice which has a superlattice conduction band energy level structure in k-vector space. The layer thicknesses of the quantum well layers are selected to provide a superlattice L/sub 2D/-valley which has a shape which is substantially more two-dimensional than that of said bulk L-valley. 2 figs.

  12. Investigation of iron cobalt nanocomposites for high frequency applications

    NASA Astrophysics Data System (ADS)

    Miller, Kelsy J.

    FeCo-based nanocomposite soft magnetic materials were developed in collaboration with Magnetics, Division of Spang and Co., for high frequency and high temperature application. Excellent soft magnetic properties include: low coercivity, high permeability, low energy losses, etc. These and large saturation inductions make these alloys attractive for fundamental studies and industrial applications. In this thesis, nanocrystalline composites will be developed from amorphous precursors for applications in two frequency regimes: 1) High frequency (0.01-30 MHz) such as high temperature power inductors, pulsed power transformers, and radio frequency (rf) magnetic heating; and 2) Ultra high frequency (30 MHz - 30 GHz) for radio frequency materials and electromagnetic interference (EMI) or radio frequency interference (RFI) absorption. New nanocomposites with higher saturation induction and high-temperature stability were developed with reduced glass forming elements such as Zr, Nb, Si and B. The amounts of the magnetic transition metals and early transition metal growth inhibitors were varied to determine trade-offs between higher inductions and fine microstructures and consequently low magnetic losses. Alloys having (Fe1-xCox)80+y+zNb4-y B13-zSi2Cu1 (25 ≤ x ≤ 50 and y = 0-4 and z = 0-3) nominal compositions were cast using planar flow casting (PFC) at Magnetics. Technical magnetic properties: permeability, maximum induction, remanence ratio, coercive field and high frequency magnetic losses as a function of composition and annealing temperature are reported after primary crystallization for 1 hr in a transverse magnetic field (TMF). Of note is the development of inductor cores with maximum inductions in excess of 1.76 T and 1.67 T in cores that exhibit power losses comparable with state of the art commercial soft magnetic alloys. For application in EMI/RFI absorption, FeCo-based alloys have the largest saturation induction and a tunable magnetic anisotropy which may

  13. Investigation of ultra violet (UV) resistance for high strength fibers

    NASA Astrophysics Data System (ADS)

    Said, M. A.; Dingwall, Brenda; Gupta, A.; Seyam, A. M.; Mock, G.; Theyson, T.

    Ultra long duration balloons (ULDB), currently under development by the National Aeronautics and Space Administration (NASA), requires the use of high strength fibers in the selected super-pressure pumpkin design. The pumpkin shape balloon concept allows clear separation of the load transferring functions of the major structural elements of the pneumatic envelope, the tendons and the film. Essentially, the film provides the gas barrier and transfers only local pressure load to the tendons. The tendons, in the mean time, provide the global pressure containing strength. In that manner, the strength requirement for the film only depends on local parameters. The tendon is made of p-phenylene-2,6-benzobisoxazole (PBO) fibers, which is selected due to its high strength to weight ratio when compared to other high performance, commercially available, fibers. High strength fibers, however, are known to degrade upon exposure to light, particularly at short wavelengths. This paper reports the results of an investigation of the resistance of four commercial high strength fibers to ultra violet (UV) exposure. The results indicate that exposing high strength fibers in continuous yarn form to UV led to serious loss in strength of the fibers except for Spectra® fibers. The adverse changes in mechanical behavior occurred over short duration of exposure compared to the 100 day duration targeted for these missions. UV blocking finishes to improve the UV resistance of these fibers are being investigated. The application of these specially formulated coatings is expected to lead to significant improvement of the UV resistance of these high performance fibers. In this publication, we report on the mechanical behavior of the fibers pre- and post-exposure to UV, but without application of the blocking finishes.

  14. Structural Controls on Groundwater Flow in Basement Terrains: Geophysical, Remote Sensing, and Field Investigations in Sinai

    NASA Astrophysics Data System (ADS)

    Mohamed, Lamees; Sultan, Mohamed; Ahmed, Mohamed; Zaki, Abotalib; Sauck, William; Soliman, Farouk; Yan, Eugene; Elkadiri, Racha; Abouelmagd, Abdou

    2015-09-01

    An integrated [very low frequency (VLF) electromagnetic, magnetic, remote sensing, field, and geographic information system (GIS)] study was conducted over the basement complex in southern Sinai (Feiran watershed) for a better understanding of the structural controls on the groundwater flow. The increase in satellite-based radar backscattering values following a large precipitation event (34 mm on 17-18 January 2010) was used to identify water-bearing features, here interpreted as preferred pathways for surface water infiltration. Findings include: (1) spatial analysis in a GIS environment revealed that the distribution of the water-bearing features (conductive features) corresponds to that of fractures, faults, shear zones, dike swarms, and wadi networks; (2) using VLF (43 profiles), magnetic (7 profiles) techniques, and field observations, the majority (85 %) of the investigated conductive features were determined to be preferred pathways for groundwater flow; (3) northwest-southeast- to north-south-trending conductive features that intersect the groundwater flow (southeast to northwest) at low angles capture groundwater flow, whereas northeast-southwest to east-west features that intersect the flow at high angles impound groundwater upstream and could provide potential productive well locations; and (4) similar findings are observed in central Sinai: east-west-trending dextral shear zones (Themed and Sinai Hinge Belt) impede south to north groundwater flow as evidenced by the significant drop in hydraulic head (from 467 to 248 m above mean sea level) across shear zones and by reorientation of regional flow (south-north to southwest-northeast). The adopted integrated methodologies could be readily applied to similar highly fractured basement arid terrains elsewhere.

  15. Investigation of a direct effect of nanosecond pulse electric fields on mitochondria

    NASA Astrophysics Data System (ADS)

    Estlack, Larry E.; Roth, Caleb C.; Cerna, Cesario Z.; Wilmink, Gerald J.; Ibey, Bennett L.

    2014-03-01

    The unique cellular response to nanosecond pulsed electric field (nsPEF) exposure, as compared to longer pulse exposure, has been theorized to be due to permeabilization of intracellular organelles including the mitochondria. In this investigation, we utilized a high-throughput oxygen and pH sensing system (Seahorse® XF24 extracellular flux analyzer) to assess the mitochondrial activity of Jurkat and U937 cells after nsPEF. The XF Analyzer uses a transient micro-chamber of only a few μL in specialized cell culture micro-plates to enable oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) to be monitored in real-time. We found that for nsPEF exposures of 10 pulses at 10-ns pulse width and at 50 kV/cm e-field, we were able to cause an increase in OCR in both U937 and Jurkat cells. We also found that high pulse numbers (>100) caused a significant decrease in OCR. Higher amplitude 150 kV/cm exposures had no effect on U937 cells and yet they had a deleterious effect on Jurkat cells, matching previously published 24 hour survival data. These results suggest that the exposures were modulating metabolic activity in cells possibly due to direct effects on the mitochondria themselves. To validate this hypothesis, we isolated mitochondria from U937 cells and exposed them similarly and found no significant change in metabolic activity for any pulse number. In a final experiment, we removed calcium from the buffer solution that the cells were exposed in and found that no significant enhancement in metabolic activity was observed. These results suggest that direct permeabilization of the mitochondria is unlikely a primary effect of nsPEF exposure and calcium-mediated intracellular pathway activation is likely responsible for observed pulse-induced mitochondrial effects.

  16. Nb$_3$Sn High Field Magnets for the High Luminosity LHC Upgrade Project

    SciTech Connect

    Ambrosio, Giorgio

    2015-01-01

    The High Luminosity upgrade of the Large Hadron Collider at CERN requires a new generation of high field superconducting magnets. High field large aperture quadrupoles (MQXF) are needed for the low-beta triplets close to the ATLAS and CMS detectors, and high field two-in-one dipoles (11 T dipoles) are needed to make room for additional collimation. The MQXF quadrupoles, with a field gradient of 140 T/m in 150 mm aperture, have a peak coil field of 12.1 T at nominal current. The 11 T dipoles, with an aperture of 60 mm, have a peak coil field of 11.6 T at nominal current. Both magnets require Nb3Sn conductor and are the first applications of this superconductor to actual accelerator magnets.

  17. High-field magnets using high-critical-temperature superconducting thin films

    DOEpatents

    Mitlitsky, F.; Hoard, R.W.

    1994-05-10

    High-field magnets fabricated from high-critical-temperature superconducting ceramic (HTSC) thin films which can generate fields greater than 4 Tesla are disclosed. The high-field magnets are made of stackable disk-shaped substrates coated with HTSC thin films, and involves maximizing the critical current density, superconducting film thickness, number of superconducting layers per substrate, substrate diameter, and number of substrates while minimizing substrate thickness. The HTSC thin films are deposited on one or both sides of the substrates in a spiral configuration with variable line widths to increase the field. 4 figures.

  18. High-field magnets using high-critical-temperature superconducting thin films

    DOEpatents

    Mitlitsky, Fred; Hoard, Ronald W.

    1994-01-01

    High-field magnets fabricated from high-critical-temperature superconducting ceramic (HTSC) thin films which can generate fields greater than 4 Tesla. The high-field magnets are made of stackable disk-shaped substrates coated with HTSC thin films, and involves maximizing the critical current density, superconducting film thickness, number of superconducting layers per substrate, substrate diameter, and number of substrates while minimizing substrate thickness. The HTSC thin films are deposited on one or both sides of the substrates in a spiral configuration with variable line widths to increase the field.

  19. NMR investigation of field-induced magnetic order in barium manganese oxide

    NASA Astrophysics Data System (ADS)

    Suh, Steve

    the triangular Mn5+ magnetic lattice of Ba3Mn2O8 coupled with interdimer interaction is predicted to result in incommensurate spin structure when the symmetry axis of Ba3Mn2O8 is aligned parallel to the field. Because of single ion anisotropy of the system, Ba3Mn 2O8 has phase diagram that depends on its alignment with respect to the external field[5]. This means that the microscopic spin structure is different depending on whether the material's symmetry axis is aligned parallel or perpendicular to the field. Also, since we are dealing with S = 1, we have potential to investigate spin-gap closure due to singlet and triplet states as well as triplet and quintet states if we are able to access high enough fields (15T to 30T). Measurements at National High Magnetic Field Laboratory (NHMFL), gives us a superficial taste of what it is like to be in the phase created by triplet and quintet gap closure. The temperature range allowed by the Oxford dilution refrigerator system at Brown Lab, UCLA is from 1K down to 30mK. The magnetic field range allowed by the superconducting magnet at Brown Lab, UCLA is from 0T up to 12T. This combination of temperature and field range allows us to investigate the first quantum critical point (Hc1) in detail with various NMR measurements. Normal state frequency shift as a function of temperature near Hc1 reveals behavior consistent with dilute hardcore bose gas. Analysis of the lineshapes of NMR spectra going into spin order BEC phase as a function of field, we directly observe incommensurate nature of spin order and deduce development of order parameter consistent with mean-field theory. Finally, we verify that the language of dilute 3D Bosons also applies to Ba3Mn2O8 through T1 measurements. From critical behavior inferred in T1 measurements, we complete phase boundary diagram at low temperatures and apply general concept of softening in Goldstone mode near Hc1 to describe our T 1 dependence as a function of temperature.

  20. Biaxial Flexural Strength of Poled Lead Zirconate Titanate under High Electric Field with Extended Field Range

    SciTech Connect

    Zhang, Kewei; Zeng, Fan W; Wang, Hong; Lin, Hua-Tay

    2013-01-01

    In the present work, as-received poled lead zirconate titanate, or PZT 5A, was examined using ball-on-ring (BoR) mechanical testing coupled with an electric field. Electric fields in the range of 4Ec (Ec, coercive field) with controlled loading paths were applied, and mechanical tests at a substantial number of characteristic electric field levels were conducted. Commercial electronic liquid FC-40 was used to prevent the setup from dielectric breakdown under a high electric field. Weibull strength distribution was used to interpret the mechanical strength data. The data showed that the strength levels of the PZT-5A tested under OC (open circuit) in air and in FC-40 were almost the same. It was further revealed that , for the studied cases, the effect of loading history on the biaxial flexural strength of the PZT was significant in -Ec, but not in OC or zero field as well as 4Ec . An asymmetry V curve was observed for the characteristic strength-electric field graph, and the bottom of V curve was located near the negative coercive field. Microscopy analysis showed that surface-located volume-distributed flaws were the strength limiter and responsible for the failure of the tested PZT under electromechanical loadings.

  1. Mitigated-force carriage for high magnetic field environments

    DOEpatents

    Ludtka, Gerard M; Ludtka, Gail M; Wilgen, John B; Murphy, Bart L

    2014-05-20

    A carriage for high magnetic field environments includes a first work-piece holding means for holding a first work-piece, the first work-piece holding means being disposed in an operable relationship with a work-piece processing magnet having a magnetic field strength of at least 1 Tesla. The first work-piece holding means is further disposed in operable connection with a second work-piece holding means for holding a second work-piece so that, as the first work-piece is inserted into the magnetic field, the second work-piece is simultaneously withdrawn from the magnetic field, so that an attractive magnetic force imparted on the first work-piece offsets a resistive magnetic force imparted on the second work-piece.

  2. Homogenous BSCCO-2212 Round Wires for Very High Field Magnets

    SciTech Connect

    Dr. Scott Campbell Dr. Terry Holesinger Dr. Ybing Huang

    2012-06-30

    The performance demands on modern particle accelerators generate a relentless push towards higher field magnets. In turn, advanced high field magnet development places increased demands on superconducting materials. Nb3Sn conductors have been used to achieve 16 T in a prototype dipole magnet and are thought to have the capability for {approx}18 T for accelerator magnets (primarily dipoles but also higher order multipole magnets). However there have been suggestions and proposals for such magnets higher than 20 T. The High Energy Physics Community (HEP) has identified important new physics opportunities that are enabled by extremely high field magnets: 20 to 50 T solenoids for muon cooling in a muon collider (impact: understanding of neutrinos and dark matter); and 20+ T dipoles and quadrupoles for high energy hadron colliders (impact: discovery reach far beyond present). This proposal addresses the latest SBIR solicitation that calls for grant applications that seek to develop new or improved superconducting wire technologies for magnets that operate at a minimum of 12 Tesla (T) field, with increases up to 15 to 20 T sought in the near future (three to five years). The long-term development of accelerator magnets with fields greater than 20 T will require superconducting wires having significantly better high-field properties than those possessed by current Nb{sub 3}Sn or other A15 based wires. Given the existing materials science base for Bi-2212 wire processing, we believe that Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (Bi-2212) round wires can be produced in km-long piece lengths with properties suitable to meet both the near term and long term needs of the HEP community. The key advance will be the translation of this materials science base into a robust, high-yield wire technology. While the processing and application of A15 materials have advanced to a much higher level than those of the copper oxide-based, high T{sub c} (HTS) counterparts, the HTS materials have

  3. High electric field deuterium ion sources for neutron generators

    NASA Astrophysics Data System (ADS)

    Reichenbach, Birk

    Active interrogation systems for highly enriched uranium require improved fieldable neutron sources. The target technology for deuterium-tritium neutron generators is well understood and the most significant improvement can be achieved by improving the deuterium ion source through increased output and, in some cases, lifetime of the ion source. We are developing a new approach to a deuterium ion sources based upon the field desorption/evaporation of deuterium from the surfaces of metal tips. Electrostatic field desorption (EFD) desorbs previously adsorbed deuterium as ions under the influence of high electric fields (several V/A), without removing tip material. Single etched wire tip experiments have been performed and have shown that this is difficult but can be achieved with molybdenum and tungsten tips. Electrostatic field evaporation (EFE) evaporates ultra thin deuterated titanium films as ions. It has been shown that several 10s of atomic layers can be removed within a few nanoseconds from etched tungsten tips. In the course of these studies titanium deposition and deuteration methods were studied and new detection methods developed. Space charge effects resulting from the large ion currents were identified to be the most likely cause of some unusual ion emission characteristics. In addition, on W < 110 > oriented substrates a surprising body-centered cubic crystal structure of the titanium film was found and studied. The ion currents required for neutron generator applications can be achieved by microfabrication of metal tip arrays. Field desorption studies of microfabricated field emitter tip arrays have been conducted for the first time. Maximum fields of 3 V/A have been applied to the array tip surfaces to date, although fields of ˜ 2 V/A to ˜ 2.5 V/A are more typical. Desorption of atomic deuterium ions has been observed at fields of roughly 2 V/A at room temperature. The desorption of common surface adsorbates, such as hydrogen, carbon, water, and

  4. Investigations on Cooling Mechanisms of Highly Charged Ions at HITRAP

    NASA Astrophysics Data System (ADS)

    Maero, Giancarlo; Herfurth, Frank; Kester, Oliver; Kluge, H.-Jürgen; Koszudowski, Stephen; Quint, Wolfgang; Schwarz, Stefan

    2009-03-01

    The upcoming facility HITRAP (Highly Charged Ion TRAP) at GSI will enable high-precision atomic-physics investigations on heavy, highly charged ions at extremely low energies. Species up to U92+ will be produced at the GSI accelerator complex by stripping of relativistic ions and injected into the Experimental Storage Ring (ESR) where they are electron-cooled and decelerated to 4 MeV/u. After ejection out of the ESR and further deceleration in a linear decelerator bunches of 105 ions will be injected into a Penning trap and cooled to 4 K via electron and resistive cooling. Simulations with a Particle-In-Cell (PIC) code have been carried out to study the dynamics of the ion cloud in the Cooler Trap with focus on resistive cooling in presence of space charge.

  5. Low-field MRI can be more sensitive than high-field MRI.

    PubMed

    Coffey, Aaron M; Truong, Milton L; Chekmenev, Eduard Y

    2013-12-01

    MRI signal-to-noise ratio (SNR) is the key factor for image quality. Conventionally, SNR is proportional to nuclear spin polarization, which scales linearly with magnetic field strength. Yet ever-stronger magnets present numerous technical and financial limitations. Low-field MRI can mitigate these constraints with equivalent SNR from non-equilibrium 'hyperpolarization' schemes, which increase polarization by orders of magnitude independently of the magnetic field. Here, theory and experimental validation demonstrate that combination of field independent polarization (e.g. hyperpolarization) with frequency optimized MRI detection coils (i.e. multi-turn coils using the maximum allowed conductor length) results in low-field MRI sensitivity approaching and even rivaling that of high-field MRI. Four read-out frequencies were tested using samples with identical numbers of (1)H and (13)C spins. Experimental SNRs at 0.0475T were ∼40% of those obtained at 4.7T. Conservatively, theoretical SNRs at 0.0475T 1.13-fold higher than those at 4.7T were possible despite an ∼100-fold lower detection frequency, indicating feasibility of high-sensitivity MRI without technically challenging, expensive high-field magnets. The data at 4.7T and 0.0475T was obtained from different spectrometers with different RF probes. The SNR comparison between the two field strengths accounted for many differences in parameters such as system noise figures and variations in the probe detection coils including Q factors and coil diameters. PMID:24239701

  6. Low-field MRI can be more sensitive than high-field MRI

    NASA Astrophysics Data System (ADS)

    Coffey, Aaron M.; Truong, Milton L.; Chekmenev, Eduard Y.

    2013-12-01

    MRI signal-to-noise ratio (SNR) is the key factor for image quality. Conventionally, SNR is proportional to nuclear spin polarization, which scales linearly with magnetic field strength. Yet ever-stronger magnets present numerous technical and financial limitations. Low-field MRI can mitigate these constraints with equivalent SNR from non-equilibrium ‘hyperpolarization' schemes, which increase polarization by orders of magnitude independently of the magnetic field. Here, theory and experimental validation demonstrate that combination of field independent polarization (e.g. hyperpolarization) with frequency optimized MRI detection coils (i.e. multi-turn coils using the maximum allowed conductor length) results in low-field MRI sensitivity approaching and even rivaling that of high-field MRI. Four read-out frequencies were tested using samples with identical numbers of 1H and 13C spins. Experimental SNRs at 0.0475 T were ∼40% of those obtained at 4.7 T. Conservatively, theoretical SNRs at 0.0475 T 1.13-fold higher than those at 4.7 T were possible despite an ∼100-fold lower detection frequency, indicating feasibility of high-sensitivity MRI without technically challenging, expensive high-field magnets. The data at 4.7 T and 0.0475 T was obtained from different spectrometers with different RF probes. The SNR comparison between the two field strengths accounted for many differences in parameters such as system noise figures and variations in the probe detection coils including Q factors and coil diameters.

  7. Experimental Investigation of Effectiveness of Magnetic Field on Food Freezing Process

    NASA Astrophysics Data System (ADS)

    Suzuki, Toru; Takeuchi, Yuri; Masuda, Kazunori; Watanabe, Manabu; Shirakashi, Ryo; Fukuda, Yutaka; Tsuruta, Takaharu; Yamamoto, Kazutaka; Koga, Nobumitsu; Hiruma, Naoya; Ichioka, Jun; Takai, Kiyoshi

    Recently, several food refrigeration equipments that utilize magnetic field have attracted much attention from food production companies, consumers and mass media. However, the effectiveness of the freezers is not scientifically examined. Therefore, the effectiveness should be clarified by experiments or theoretical considerations. In this study, the effect of weak magnetic field (about 0.0005 T) on freezing process of several kinds of foods was investigated by using a specially designed freezer facilitated with magnetic field generator. The investigation included the comparison of freezing curves, drip amount, physicochemical evaluations on color and texture, observation of microstructure, and sensory evaluation. From the results of the control experiments, it can be concluded that weak magnetic field around 0.0005 T provided no significant difference on temperature history during freezing and on the qualities of frozen foods, within our experimental conditions.

  8. Reflection type metasurface designed for high efficiency vectorial field generation

    NASA Astrophysics Data System (ADS)

    Wang, Shiyi; Zhan, Qiwen

    2016-07-01

    We propose a reflection type metal-insulator-metal (MIM) metasurface composed of hybrid nano-antennas for comprehensive spatial engineering of the properties of optical fields. The capability of such structure is illustrated in the design of a device that can be used to produce a radially polarized vectorial beam for optical needle field generation. This device consists of uniformly segmented sectors of high efficiency MIM metasurface. With each of the segment sector functioning as a local quarter-wave-plate (QWP), the device is designed to convert circularly polarized incidence into local linear polarization to create an overall radial polarization with corresponding binary phases and extremely high dynamic range amplitude modulation. The capability of such devices enables the generation of nearly arbitrarily complex optical fields that may find broad applications that transcend disciplinary boundaries.

  9. Iron-based superconductors in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Coldea, Amalia I.; Braithwaite, Daniel; Carrington, Antony

    2013-01-01

    Here we review measurements of the normal and superconducting state properties of iron-based superconductors using high magnetic fields. We discuss the various physical mechanisms that limit superconductivity in high fields, and the information on the superconducting state that can be extracted from the upper critical field, but also how thermal fluctuations affect its determination by resistivity and specific heat measurements. We also discuss measurements of the normal state electronic structure focusing on measurement of quantum oscillations, particularly the de Haas-van Alphen effect. These results have determined very accurately, the topology of the Fermi surface and the quasi-particle masses in a number of different iron-based superconductors, from the 1111, 122 and 111 families.

  10. Reflection type metasurface designed for high efficiency vectorial field generation.

    PubMed

    Wang, Shiyi; Zhan, Qiwen

    2016-01-01

    We propose a reflection type metal-insulator-metal (MIM) metasurface composed of hybrid nano-antennas for comprehensive spatial engineering of the properties of optical fields. The capability of such structure is illustrated in the design of a device that can be used to produce a radially polarized vectorial beam for optical needle field generation. This device consists of uniformly segmented sectors of high efficiency MIM metasurface. With each of the segment sector functioning as a local quarter-wave-plate (QWP), the device is designed to convert circularly polarized incidence into local linear polarization to create an overall radial polarization with corresponding binary phases and extremely high dynamic range amplitude modulation. The capability of such devices enables the generation of nearly arbitrarily complex optical fields that may find broad applications that transcend disciplinary boundaries. PMID:27417150

  11. Reflection type metasurface designed for high efficiency vectorial field generation

    PubMed Central

    Wang, Shiyi; Zhan, Qiwen

    2016-01-01

    We propose a reflection type metal-insulator-metal (MIM) metasurface composed of hybrid nano-antennas for comprehensive spatial engineering of the properties of optical fields. The capability of such structure is illustrated in the design of a device that can be used to produce a radially polarized vectorial beam for optical needle field generation. This device consists of uniformly segmented sectors of high efficiency MIM metasurface. With each of the segment sector functioning as a local quarter-wave-plate (QWP), the device is designed to convert circularly polarized incidence into local linear polarization to create an overall radial polarization with corresponding binary phases and extremely high dynamic range amplitude modulation. The capability of such devices enables the generation of nearly arbitrarily complex optical fields that may find broad applications that transcend disciplinary boundaries. PMID:27417150

  12. Extended depth of field imaging for high speed object analysis

    NASA Technical Reports Server (NTRS)

    Ortyn, William (Inventor); Basiji, David (Inventor); Frost, Keith (Inventor); Liang, Luchuan (Inventor); Bauer, Richard (Inventor); Hall, Brian (Inventor); Perry, David (Inventor)

    2011-01-01

    A high speed, high-resolution flow imaging system is modified to achieve extended depth of field imaging. An optical distortion element is introduced into the flow imaging system. Light from an object, such as a cell, is distorted by the distortion element, such that a point spread function (PSF) of the imaging system is invariant across an extended depth of field. The distorted light is spectrally dispersed, and the dispersed light is used to simultaneously generate a plurality of images. The images are detected, and image processing is used to enhance the detected images by compensating for the distortion, to achieve extended depth of field images of the object. The post image processing preferably involves de-convolution, and requires knowledge of the PSF of the imaging system, as modified by the optical distortion element.

  13. High-temperature structural phase transitions in neighborite: a high-resolution neutron powder diffraction investigation

    NASA Astrophysics Data System (ADS)

    Knight, Kevin S.; Price, G. David; Stuart, John A.; Wood, Ian G.

    2015-01-01

    The nature of the apparently continuous structural phase transition at 1,049 K in the perovskite-structured, MgSiO3 isomorph, neighborite (NaMgF3), from the orthorhombic ( Pbnm) hettotype phase to the cubic () aristotype structure, has been re-investigated using high-resolution, time-of-flight neutron powder diffraction. Using data collected at 1 K intervals close to the nominal phase transition temperature, the temperature dependence of the intensities of superlattice reflections at the M point and the R point of the pseudocubic Brillouin zone indicate the existence of a new intermediate tetragonal phase in space group P4/ mbm, with a narrow phase field extending from ~1,046.5 to ~1,048.5 K, at ambient pressure. Group theoretical analysis shows that the structural transitions identified in this study, Pbnm- P4/ mbm, and P4/ mbm-, are permitted to be second order. The observation of the tetragonal phase resolves the longstanding issue of why the high-temperature phase transition, previously identified as Pbnm-, and which would be expected to be first order under Landau theory, is in fact found to be continuous. Analysis of the pseudocubic shear strain shows it to vary with a critical exponent of 0.5 implying that the phase transition from Pbnm to P4/ mbm is tricritical in character. The large librational modes that exist in the MgF6 octahedron at high temperature, and the use of Gaussian probability density functions to describe atomic displacements, result in apparent bond shortening in the Mg-F distances, making mode amplitude determination an unreliable method for determination of the critical exponent from internal coordinates. Crystal structures are reported for the three phases of NaMgF3 at 1,033 K ( Pbnm), 1,047 K ( P4/ mbm) and 1,049 K ().

  14. Innovative Field Emitters for High-Voltage Electronic Devices

    NASA Astrophysics Data System (ADS)

    Sominski, G. G.; Sezonov, V. E.; Taradaev, E. P.; Tumareva, T. A.; Zadiranov, Yu. M.; Kornishin, S. Yu.; Stepanova, A. N.

    2015-12-01

    We describe multitip field emitters with protective coatings, which were developed in Peter the Great St. Petersburg Polytechnic University. The coatings ensure long-term operation of the emitters under high currents and technical vacuum. Innovative multi-layer emitters composed of contacting nanolayers of materials with different work functions are presented as well. The possibility by using the developed emitters in high-voltage electronic devices is demonstrated.

  15. FLASH requirements for the high intensity radiated field electromagnetic environment

    NASA Astrophysics Data System (ADS)

    Murdock, John K.

    1995-05-01

    The worldwide proliferation of high intensity emitting sources and the more electric aircraft increase the intensity of the Electromagnetic Environment (EME) in which aircraft must operate. A FLASH program HIRF (High Intensity Radiated Field) EME requirement is derived to cover both commercial and military fixed and rotary wing aircraft. This requirement is derived from the radiated susceptibility requirement documents of both the FAA and U.S. military. Specific test data and analysis will show that we can meet this requirement.

  16. Field-effect transistor having a superlattice channel and high carrier velocities at high applied fields

    DOEpatents

    Chaffin, deceased, Roger J.; Dawson, Ralph; Fritz, Ian J.; Osbourn, Gordon C.; Zipperian, Thomas E.

    1989-01-01

    A field effect transistor comprises a semiconductor having a source, a drain, a channel and a gate in operational relationship. The semiconductor is a strained layer superlattice comprising alternating quantum well and barrier layers, the quantum well layers and barrier layers being selected from the group of layer pairs consisting of InGaAs/AlGaAs, InAs/InAlGaAs, and InAs/InAlAsP. The layer thicknesses of the quantum well and barrier layers are sufficiently thin that the alternating layers constitute a superlattice which has a superlattice conduction band energy level structure in k-vector space which includes a lowest energy .GAMMA.-valley and a next lowest energy L-valley, each k-vector corresponding to one of the orthogonal directions defined by the planes of said layers and the directions perpendicular thereto. The layer thicknesses of the quantum well layers are selected to provide a superlattice L.sub.2D -valley which has a shape which is substantially more two-dimensional than that of said bulk L-valley.

  17. Experimental investigation of the visual field dependency in the erect and supine positions

    NASA Technical Reports Server (NTRS)

    Lichtenstein, J. H.; Saucer, R. T.

    1972-01-01

    The increasing utilization of simulators in many fields, in addition to aeronautics and space, requires the efficient use of these devices. It seemed that personnel highly influenced by the visual scene would make desirable subjects, particularly for those simulators without sufficient motion cues. In order to evaluate this concept, some measure of the degree of influence of the visual field on the subject in necessary. As part of this undertaking, 37 male and female subjects, including eight test pilots, were tested for their visual field dependency or independency. A version of Witkin's rod and frame apparatus was used for the tests. The results showed that nearly all the test subjects exhibited some degree of field dependency, the degree varying from very high field dependency to nearly zero field dependency in a normal distribution. The results for the test pilots were scattered throughout a range similar to the results for the bulk of male subjects. The few female subjects exhibited a higher field dependency than the male subjects. The male subjects exhibited a greater field dependency in the supine position than in the erect position, whereas the field dependency of the female subjects changed only slightly.

  18. Comparative investigation of three dose rate meters for their viability in pulsed radiation fields.

    PubMed

    Gotz, M; Karsch, L; Pawelke, J

    2015-06-01

    Pulsed radiation fields, characterized by microsecond pulse duration and correspondingly high pulse dose rates, are increasingly used in therapeutic, diagnostic and research applications. Yet, dose rate meters which are used to monitor radiation protection areas or to inspect radiation shielding are mostly designed, characterized and tested for continuous fields and show severe deficiencies in highly pulsed fields. Despite general awareness of the problem, knowledge of the specific limitations of individual instruments is very limited, complicating reliable measurements. We present here the results of testing three commercial dose rate meters, the RamION ionization chamber, the LB 1236-H proportional counter and the 6150AD-b scintillation counter, for their response in pulsed radiation fields of varied pulse dose and duration. Of these three the RamION proved reliable, operating in a pulsed radiation field within its specifications, while the other two instruments were only able to measure very limited pulse doses and pulse dose rates reliably. PMID:25978117

  19. FIELD EVALUATION OF A HIGH-VOLUME DICHOTOMOUS SAMPLER

    EPA Science Inventory

    This study presents the field evaluation of a high-volume dichotomous sampler that collects coarse (PM10-2.5) and fine (PM2.5) particulate matter. The key feature of this device is the utilization of a round-nozzle virtual impactor with a 50% cutpoint at 2.5 5m to split PM10 into...

  20. Survey of high field superconducting material for accelerator magnets

    SciTech Connect

    Scahlan, R.; Greene, A.F.; Suenaga, M.

    1986-05-01

    The high field superconductors which could be used in accelerator dipole magnets are surveyed, ranking these candidates with respect to ease of fabrication and cost as well as superconducting properties. Emphasis is on Nb/sub 3/Sn and NbTi. 27 refs., 2 figs. (LEW)

  1. Remedial investigation report for J-Field, Aberdeen Proving Ground, Maryland. Volume 3: Ecological risk assessment

    SciTech Connect

    Hlohowskyj, I.; Hayse, J.; Kuperman, R.; Van Lonkhuyzen, R.

    2000-02-25

    The Environmental Management Division of the U.S. Army Aberdeen Proving Ground (APG), Maryland, is conducting a remedial investigation (RI) and feasibility study (FS) of the J-Field area at APG, pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended. As part of that activity, Argonne National Laboratory (ANL) conducted an ecological risk assessment (ERA) of the J-Field site. This report presents the results of that assessment.

  2. Wave propagation downstream of a high power helicon in a dipolelike magnetic field

    NASA Astrophysics Data System (ADS)

    Prager, James; Ziemba, Timothy; Winglee, Robert; Roberson, B. Race

    2010-01-01

    The wave propagating downstream of a high power helicon source in a diverging magnetic field was investigated experimentally. The magnetic field of the wave has been measured both axially and radially. The three-dimensional structure of the propagating wave is observed and its wavelength and phase velocity are determined. The measurements are compared to predictions from helicon theory and that of a freely propagating whistler wave. The implications of this work on the helicon as a thruster are also discussed.

  3. Wave propagation downstream of a high power helicon in a dipolelike magnetic field

    SciTech Connect

    Prager, James; Winglee, Robert; Roberson, B. Race; Ziemba, Timothy

    2010-01-15

    The wave propagating downstream of a high power helicon source in a diverging magnetic field was investigated experimentally. The magnetic field of the wave has been measured both axially and radially. The three-dimensional structure of the propagating wave is observed and its wavelength and phase velocity are determined. The measurements are compared to predictions from helicon theory and that of a freely propagating whistler wave. The implications of this work on the helicon as a thruster are also discussed.

  4. A statistical study of high-altitude electric fields measured on the Viking satellite

    SciTech Connect

    Lindqvist, P.A.; Marklund, G.T. )

    1990-05-01

    Characteristics of high-altitude data from the Viking electric field instrument are presented in a statistical study based on 109 Viking orbits. The study is focused in particular on the signatures of and relationships between various parameters measured by the electric field instrument, such as the parallel and transverse (to B) components of the electric field instrument, such as electric field variability. A major goal of the Viking mission was to investigate the occurrence and properties of parallel electric fields and their role in the auroral acceleration process. The results in this paper on the altitude distribution of the electric field variability confirm earlier findings on the distribution of small-scale electric fields and indicate the presence of parallel fields up to about 11,000 km altitude. The directly measured parallel electric field is also investigated in some detail. It is in general directed upward with an average value of 1 mV/m, but depends on, for example, altitude and plasma density. Possible sources of error in the measurement of the parallel field are also considered and accounted for.

  5. Investigating microbial transformations of soil organic matter: synthesizing knowledge from disparate fields to guide new experimentation

    NASA Astrophysics Data System (ADS)

    Billings, S. A.; Tiemann, L. K.; Ballantyne, F., IV; Lehmeier, C. A.; Min, K.

    2015-04-01

    Discerning why some soil organic matter (SOM) leaves soil profiles relatively quickly while other compounds, especially at depth, can be retained for decades to millennia is challenging for a multitude of reasons. Simultaneous with soil-specific advances, multiple other disciplines have enhanced their knowledge bases in ways potentially useful for future investigations of SOM decay. In this article, we highlight observations highly relevant for those investigating SOM decay and retention but often emanating from disparate fields and residing in literature seldom cited in SOM research. We focus on recent work in two key areas. First, we turn to experimental approaches using natural and artificial aquatic environments to investigate patterns of microbially mediated OM transformations as environmental conditions change, and highlight how aquatic microbial responses to environmental change can reveal processes likely important to OM decay and retention in soils. Second, we emphasize the importance of establishing intrinsic patterns of decay kinetics for purified substrates commonly found in soils to develop baseline rates. These decay kinetics - which represent the upper limit of the reaction rates - can then be compared to substrate decay kinetics observed in natural samples, which integrate intrinsic decay reaction rates and edaphic factors essential to the site under study but absent in purified systems. That comparison permits the site-specific factors to be parsed from the fundamental decay kinetics, an important advance in our understanding of SOM decay (and thus persistence) in natural systems. We then suggest ways in which empirical observations from aquatic systems and purified substrate-enzyme reaction kinetics can be used to advance recent theoretical efforts in SOM-focused research. Finally, we suggest how the observations in aquatic and purified substrate-enzyme systems could be used to help unravel the puzzles presented by oft-observed patterns of SOM

  6. Limited field investigation report for the 100-HR-1 Operable Unit

    SciTech Connect

    Not Available

    1994-08-01

    This limited field investigation (LFI) report summarizes the data collection and analysis activities conducted during the 100-HR-1 Source Operable Unit LFI and the associated qualitative risk assessment (QRA) (WHC 1993a), and makes recommendations on the continued candidacy of high-priority sites for interim remedial measures (IRM). The results and recommendations presented in this report are generally independent of future land use scenarios. A LFI Report is required, in accordance with the HPPS, when waste sites are to be considered for IRMs. The LFI is an integral part of the remedial investigation/feasibility study (RI/FS) or Resource Conservation and Recovery Act (RCRA) facility investigation/corrective measures study (RFI/CMS) and process and functions as a focused RI or RFI for selection of IRMs. The purpose of the report is to identify those sites that are recommended to remain as candidates for IRMs, provide a preliminary summary of site characterization studies, refine the conceptual model as needed, identify contaminant- and location-specific applicable or relevant and appropriate requirements (ARA), and provide a qualitative assessment of the risks associated with the sites. This assessment includes consideration of whether contaminant concentrations pose an unacceptable risk that warrants action through IRMs. The 100-HR-1 unit encompasses approximately 100 acres adjacent to the Columbia River shoreline. It contains waste units associated with the original plant facilities constructed to support the H Reactor. The area also contains evaporation basins which received liquid process wastes and nonroutine deposits of chemical wastes from the 300 Area, where fuel elements for the N Reactor were produced.

  7. Magnetic fields end-face effect investigation of HTS bulk over PMG with 3D-modeling numerical method

    NASA Astrophysics Data System (ADS)

    Qin, Yujie; Lu, Yiyun

    2015-09-01

    In this paper, the magnetic fields end-face effect of high temperature superconducting (HTS) bulk over a permanent magnetic guideway (PMG) is researched with 3D-modeling numerical method. The electromagnetic behavior of the bulk is simulated using finite element method (FEM). The framework is formulated by the magnetic field vector method (H-method). A superconducting levitation system composed of one rectangular HTS bulk and one infinite long PMG is successfully investigated using the proposed method. The simulation results show that for finite geometrical HTS bulk, even the applied magnetic field is only distributed in x-y plane, the magnetic field component Hz which is along the z-axis can be observed interior the HTS bulk.

  8. High-field electron transport in GaN under crossed electric and magnetic fields

    NASA Astrophysics Data System (ADS)

    Kochelap, V. A.; Korotyeyev, V. V.; Syngayivska, G. I.; Varani, L.

    2015-10-01

    High-field electron transport studied in crossed electric and magnetic fields in bulk GaN with doping of 1016 cm-3, compensation around 90% at the low lattice temperature (30 K). It was found the range of the magnetic and electric fields where the non-equilibrium electron distribution function has a complicated topological structure in the momentum space with a tendency to the formation of the inversion population. Field dependences of dissipative and Hall components of the drift velocity were calculated for the samples with short- and open- circuited Hall contacts in wide ranges of applied electric (0 — 20 kV/cm) and magnetic (1 — 10 T) fields. For former sample, field dependences of dissipative and Hall components of the drift velocity have a non-monotonic behavior. The dissipative component has the inflection point which corresponds to the maximum point of the Hall component. For latter sample, the drift velocity demonstrate a usual sub-linear growth without any critical points. We found that GaN samples with controlled resistance of the Hall circuit can be utilized as a electronic high-power switch.

  9. SITE IVESTIGATIONS (SI) AND FIELD INVESTIGATIONS (FI) OF REGION 4 SUPERFUND HAZARDOUS WASTE SITES: OCTOBER 2005 – SEPTEMBER 2006

    EPA Science Inventory

    Site Investigations (SIs) and expanded Field Investigations (FIs) conducted by the Region 4 Science and Ecosystem Support Division (SESD) require developing and implementing work plans which include a Project Operations Plan, Field Sampling and Analysis Plan, Quality Assurance Pl...

  10. SITE IVESTIGATIONS (SI) AND FIELD INVESTIGATIONS (FI) OF REGION 4 SUPERFUND HAZARDOUS WASTE SITES: AUGUST 2007 – SEPTEMBER 2008

    EPA Science Inventory

    Site Investigations (SIs) and Field Investigations (FIs) conducted by the Region 4 Science and Ecosystem Support Division (SESD) require developing and implementing work plans which include a Project Operations Plan, Field Sampling and Analysis Plan, Quality Assurance Project Pla...

  11. Investigation of Electric and Self-Generated Magnetic Fields in Implosion Experiments on OMEGA

    NASA Astrophysics Data System (ADS)

    Igumenshchev, I. V.; Nilson, P. M.; Goncharov, V. N.; Li, C. K.; Zylstra, A. B.; Petrasso, R. D.

    2013-10-01

    Electric and self-generated magnetic fields in direct-drive implosion experiments on the OMEGA laser were investigated using proton radiography. The experiments use plastic-shell targets with various surface defects (glue spot, wire, and stalk mount) to seed perturbations and generate localized electromagnetic fields at the ablation surface and in the plasma corona surrounding the targets. Proton radiographs show features from these perturbations and quasi-spherical multiple shell structures around the capsules at earlier times of implosions (up to ~700 ps for a 1-ns laser pulse) indicating the development of the fields. Two-dimensional magnetohydrodynamic simulations of these experiments predict the growth of magnetic fields up to several MG. The simulated distributions of electromagnetic fields were used to produce proton images, which show good agreement with experimental radiographs. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  12. Theoretical investigation of boundary contours of ground-state atoms in uniform electric fields

    NASA Astrophysics Data System (ADS)

    Shi, Hua; Zhao, Dong-Xia; Yang, Zhong-Zhi

    2015-12-01

    The boundary contours were investigated for first 54 ground-state atoms of the periodic table when they are in uniform electric fields of strengths 106, 107 and 108 V/m. The atomic characteristic boundary model in combination with an ab-initio method was employed. Some regularities of the deformation of atoms, ΔR, in above electric fields are revealed. Furthermore, atomic polarisabilities of the first 54 elements of the periodic table are shown to correlate strongly with the mean variation rate of atomic radial size divided by the strength of the electric field F, ?, which provides a predictive method of calculating atomic polarisabilities of 54 atoms.

  13. Geometric optical investigation of the underwater visual field of aerial animals.

    PubMed

    Horváth, G; Varjú, D

    1990-11-01

    The underwater visual field distorted by refraction for aerial animals living near the water surface is investigated by means of geometric optics. The imaging of underwater objects by one and two aerial eyes is studied. The underwater binocular image field is determined for pairs of aerial eyes placed in horizontal and vertical planes. Some possible biooptical consequences of the visual detection of underwater prey and predator by aerial animals are discussed on the basis of the structure of their distorted visual field. PMID:2134486

  14. Experimental Investigation of Pool Boiling Heat Transfer Enhancement in Microgravity in the Presence of Electric Fields

    NASA Technical Reports Server (NTRS)

    Herman, C.

    2000-01-01

    The research carried out in the Heat Transfer Laboratory of the Johns Hopkins University was motivated by previous studies indicating that in terrestrial applications nucleate boiling heat transfer can be increased by a factor of 50 when compared to values obtained for the same system without electric fields. Imposing an external electric field holds the promise to improve pool boiling heat transfer in low gravity, since a phase separation force other than gravity is introduced. The influence of electric fields on bubble formation has been investigated both experimentally and theoretically.

  15. Optical investigation of effective permeability of dilute magnetic dielectrics with magnetic field

    NASA Astrophysics Data System (ADS)

    Banerjee, Ananya; Sarkar, A.

    2016-05-01

    The prime objective of this paper is to investigate the magnetic nature of dilute magnetic dielectrics (DMD) under variation of external magnetic field. The said variation is studied over developed nano-sized Gadolinium Oxide as a DMD system. The observed experimental field variation of the effective magnetic permeability is analyzed results of optical experiment. The experiment records the variation of Brewster angle of incident polarized LASER beam from the surface of developed DMD specimen with applied out of plane external magnetic field. The effective refractive index and hence relative magnetic permeability were estimated following electro-magnetic theory. The overall results obtained and agreement between theory and experiment are good.

  16. Investigation of different magnetic field configurations using an electrical, modular Zeeman slower

    SciTech Connect

    Ohayon, Ben; Ron, Guy

    2015-10-15

    We present a method of constructing an automatically reconfigurable, modular, electronic Zeeman slower, which is remotely controlled. This setup is used to investigate the ability of different magnetic field profiles to slow thermal atoms to the capture velocity of a magneto-optical-trap. We show that a simple numerical optimization process yields better results than the commonly used approach for deciding on the appropriate field and comes close to the optimum field, found by utilizing a fast feedback loop which uses a genetic algorithm. Our new numerical method is easily adaptable to a variety of existing slower designs and may be beneficial where feedback is unavailable.

  17. Investigation of quasi lateral-field-excitation on (yxl)-17° LiNbO3 single crystal.

    PubMed

    Ma, Tingfeng; Wang, Ji; Du, Jianke; Yuan, Lili; Qian, Zhenghua; Zhang, Zhitian; Zhang, Chao

    2014-04-01

    Quasi lateral-field-excitation (LFE) on LiNbO3 crystal is investigated both theoretically and experimentally. It is found that when the driving electric field direction is parallel to the crystallographic X-axis of the piezoelectric substrate, (yxl)-17° LiNbO3 LFE bulk acoustic wave devices work on quasi-LFE mode. The experimental results agreed with the theoretical prediction well. The results provide the cut of LiNbO3 crystal for quasi-LFE bulk acoustic wave devices, which is important for designing high performance LFE sensors on LiNbO3 substrates. PMID:24485749

  18. Si:P as a laboratory analogue for hydrogen on high magnetic field white dwarf stars.

    PubMed

    Murdin, B N; Li, Juerong; Pang, M L Y; Bowyer, E T; Litvinenko, K L; Clowes, S K; Engelkamp, H; Pidgeon, C R; Galbraith, I; Abrosimov, N V; Riemann, H; Pavlov, S G; Hübers, H-W; Murdin, P G

    2013-01-01

    Laboratory spectroscopy of atomic hydrogen in a magnetic flux density of 10(5) T (1 gigagauss), the maximum observed on high-field magnetic white dwarfs, is impossible because practically available fields are about a thousand times less. In this regime, the cyclotron and binding energies become equal. Here we demonstrate Lyman series spectra for phosphorus impurities in silicon up to the equivalent field, which is scaled to 32.8 T by the effective mass and dielectric constant. The spectra reproduce the high-field theory for free hydrogen, with quadratic Zeeman splitting and strong mixing of spherical harmonics. They show the way for experiments on He and H(2) analogues, and for investigation of He(2), a bound molecule predicted under extreme field conditions. PMID:23403570

  19. Compound specific isotope analysis to investigate pesticide degradation in lysimeter experiments at field conditions

    NASA Astrophysics Data System (ADS)

    Ryabenko, Evgenia; Elsner, Martin; Bakkour, Rani; Hofstetter, Thomas; Torrento, Clara; Hunkeler, Daniel

    2015-04-01

    The frequent detection of organic micropollutants such as pesticides, consumer care products or pharmaceuticals in water is an increasing concern for human and ecosystem health. Degradation analysis of these compounds can be challenging in complex systems due to the fact that metabolites are not always found and mass balances frequently cannot be closed. Many abiotic and biotic degradation pathways cause, however, distinct isotope fractionation, where light isotopes are transferred preferentially from the reactant to the product pool (normal isotope fractionation). Compound-specific isotope analysis (CSIA) of multiple elements is a particularly powerful method to evaluate organic micropollutant transformation, because it can even give pathway-specific isotope fractionation (1,2). Available CSIA field studies, however, have focused almost exclusively on volatile petroleum and chlorinated hydrocarbons, which are present in high concentrations in the environment and can be extracted easily from water for GC-IRMS analysis. In the case of micropollutants, such as pesticides, CSIA in more challenging since it needs to be conducted at lower concentrations and requires pre-concentration, purification and high chromatographic performance (3). In this study we used lysimeters experiments to analyze transformation of atrazine, acetochlor, metolachlor and chloridazone by studying associated isotope fractionation. The project combines a) analytical method development for CSIA, b) identification of pathways of micropollutant degradation and c) quantification of transformation processes under field condition. The pesticides were applied both, at the soil surface and below the top soil under field-relevant concentrations in May 2014. After typical irrigation of the lysimeters, seepage water was collected in 50L bottles and stored for further SPE and CSIA. Here we present the very first result of a) analytical method development, b) improvement of SPE methods for complex pesticide

  20. Investigation of high-energy-proton effects in aluminum

    SciTech Connect

    Czajkowski, C.J.; Snead, C.L. Jr.; Todosow, M.

    1997-12-01

    Specimens of 1100 aluminum were exposed to several fluences of 23.5-GeV protons at the Brookhaven Alternating Gradient Synchrotron. Although this energy is above those currently being proposed for spallation-neutron applications, the results can be viewed as indicative of trends and other microstructural evolution with fluence that take place with high-energy proton exposures such as those associated with an increasing ratio of gas generation to dpa. TEM investigation showed significantly larger bubble size and lower density of bubbles compared with lower-energy proton results. Additional testing showed that the tensile strength increased with fluence as expected, but the microhardness decreased, a result for which an intepretation is still under investigation.

  1. Numerical Investigations of High Pressure Acoustic Waves in Resonators

    NASA Technical Reports Server (NTRS)

    Athavale, Mahesh; Pindera, Maciej; Daniels, Christopher C.; Steinetz, Bruce M.

    2004-01-01

    This presentation presents work on numerical investigations of nonlinear acoustic phenomena in resonators that can generate high-pressure waves using acoustic forcing of the flow. Time-accurate simulations of the flow in a closed cone resonator were performed at different oscillation frequencies and amplitudes, and the numerical results for the resonance frequency and fluid pressure increase match the GRC experimental data well. Work on cone resonator assembly simulations has started and will involve calculations of the flow through the resonator assembly with and without acoustic excitation. A new technique for direct calculation of resonance frequency of complex shaped resonators is also being investigated. Script-driven command procedures will also be developed for optimization of the resonator shape for maximum pressure increase.

  2. Comparison and Properties of Near-Field and Far-Field Events of High Speed Jet

    NASA Astrophysics Data System (ADS)

    Kan, Pinqing; Lewalle, Jacques

    2013-11-01

    Two independent algorithms are applied to different signals to extract events that are potentially responsible for jet noise production. The data consist of 10 kHz TRPIV measurement and pressure sampling in both near- and far-field. One method uses near-field diagnostics (representatives of 2D velocity sections, e.g. velocity, vorticity, Q criterion, etc.) and near-field and far-field pressure. Applying cross-correlation and continuous wavelet to pairs of these signals, we look for the more dominant events in the time, frequency and lag domain. These are regarded as the main contributors of communication between the selected signals and are recorded as Near-Field Events. The other method only uses far-field microphones. The short time excerpts are identified as Far-Field Events that are common to three FF signals and responsible for peak energy spectrum. To compare these events, we map out their property distribution, including frequency, magnitude and time of occurrence. The individual events are also compared and a high portion is found to be common to both lists. We regard this as a verification of both algorithms. This work is supported in part by a Syracuse University Graduate Fellowship, by the Department of Mechanical and Aerospace Engineering at SU, and by Spectral Energies LLC, under an SBIR grant from AFRL.

  3. Ionization of highly excited helium atoms in an electric field

    SciTech Connect

    van de Water, W.; Mariani, D.R.; Koch, P.M.

    1984-11-01

    We present detailed measurements of ionization of highly excited triplet helium atoms in a static electric field. The atoms were prepared in states with energy E close to the saddle-point threshold E = -2(F(a.u.))/sup 1/2/. The electric field F was sufficiently strong for the states to be characterized by total spin S and absolute value of the magnetic quantum number M/sub L/. For M/sub L/ = 0 states the experiments measured ionization properties of adiabatic states. In another case, Vertical BarM/sub L/Vertical Bar = 2, they predominantly measured those of diabatic states. In both cases the ionization rate was found to be a highly nonmonotonic function of the field strength. The observations are analyzed in terms of a theory of the helium density of states in an electric field. A companion paper (D. A. Harmin, Phys. Rev. A 30, 2413 (1984)) develops in detail the general theory, which uses quantum defects to parametrize the effect of the core interaction. The agreement between measured and calculated ionization curves is good, indicating that the field ionization of a nonhydrogenic atom can now be understood in a detailed, quantitative, and predictive sense.

  4. High field magnetic resonance imaging-based gel dosimetry for small radiation fields

    NASA Astrophysics Data System (ADS)

    Ding, Xuanfeng

    Small megavoltage photon radiation fields (< 3cm diameter) are used in advanced radiation therapy techniques, such as intensity modulated radiotherapy, and stereotactic radiosurgery, as well as for cellular and preclinical radiobiology studies (very small fields, <1 mm diameter). Radiation dose characteristics for these small fields are difficult to determine in multiple dimensions because of steep dose gradients (30--40% per mm) and conditions of electronic disequilibrium. Conventional radiation dosimetry techniques have limitations for small fields because detector size may be large compared to radiation field size and/or dose acquisition may be restricted to one or two dimensions. Polymer gel dosimetry, is a three-dimensional (3D) dosimeter based on radiation-induced polymerization of tissue equivalent gelatin. Polymer gel dosimeters can be read using magnetic resonance imaging (MRI), which detects changes in relaxivity due to gel polymerization. Spatial resolution for dose readout is limited to 0.25--0.5mm pixel size because of available the magnetic field strengths (1.5T and 3T) and the stability of polymer gelatin at room temperature. A reliable glucose-based MAGIC (methacrylic and ascorbic acid in gelatine initiated by copper) gel dosimeter was formulated and evaluated for small field 3D dosimetry using 3T and 7T high field MRI for dose readout. The melting point of the original recipe MAGIC gel was increased by 4°C by adding 10% glucose to improve gel stability. Excellent spatial resolution of 79um (1.5 hr scan) and 39um (12 hr scan) was achieved using 7T MRI, proving gel stability for long scan times and high resolution 3D dosimetry.

  5. Mechanical design of a high field common coil magnet

    SciTech Connect

    Caspi, S.; Chow, K.; Dietderich, D.; Gourlay, S.; Gupta, R.; McInturff, A.; Millos, G.; Scanlan, R.

    1999-03-18

    A common coil design for high field 2-in-1 accelerator magnets has been previously presented as a 'conductor-friendly' option for high field magnets applicable for a Very Large Hadron Collider. This paper presents the mechanical design for a 14 tesla 2-in-1 dipole based on the common coil design approach. The magnet will use a high current density Nb{sub 3}Sn conductor. The design addresses mechanical issues particular to the common coil geometry: horizontal support against coil edges, vertical preload on coil faces, end loading and support, and coil stresses and strains. The magnet is the second in a series of racetrack coil magnets that will provide experimental verification of the common coil design approach.

  6. High Field Small Animal Magnetic Resonance Oncology Studies

    PubMed Central

    Bokacheva, Louisa; Ackerstaff, Ellen; LeKaye, H. Carl; Zakian, Kristen; Koutcher, Jason A.

    2014-01-01

    This review focuses on the applications of high magnetic field magnetic resonance imaging (MRI) and spectroscopy (MRS) to cancer studies in small animals. High field MRI can provide information about tumor physiology, the microenvironment, metabolism, vascularity and cellularity. Such studies are invaluable for understanding tumor growth and proliferation, response to treatment and drug development. The MR techniques reviewed here include 1H, 31P, Chemical Exchange Saturation Transfer (CEST) imaging, and hyperpolarized 13C MR spectroscopy as well as diffusion-weighted, Blood Oxygen Level Dependent (BOLD) contrast imaging, and dynamic contrast-enhanced MR imaging. These methods have been proven effective in animal studies and are highly relevant to human clinical studies. PMID:24374985

  7. High field superconductor development and understanding project, Final Report

    SciTech Connect

    Larbalestier, David C.; Lee, Peter J.

    2009-07-15

    Over 25 years the Applied Superconductivity Center at the University of Wisconsin-Madison provided a vital technical resource to the High Energy Physics community covering development in superconducting strand for HEP accelerator magnet development. In particular the work of the group has been to develop the next generation of high field superconductors for high field application. Grad students Mike Naus, Chad Fischer, Arno Godeke and Matt Jewell improved our understanding of the microstructure and microchemistry of Nb3Sn and their impact on the physical and mechanical properties. The success of this work has led to the continued funding of this work at the ASC after it moved to the NHMFL and also to direct funding from BNL for some aspects of Nb3Sn cable evaluation.

  8. Investigation of high efficiency GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Olsen, Larry C.; Dunham, Glen; Addis, F. W.; Huber, Dan; Linden, Kurt

    1989-01-01

    Investigations of basic mechanisms which limit the performance of high efficiency GaAs solar cells are discussed. P/N heteroface structures have been fabricated from MOCVD epiwafers. Typical AM1 efficiencies are in the 21 to 22 percent range, with a SERI measurement for one cell being 21.5 percent. The cells are nominally 1.5 x 1.5 cm in size. Studies have involved photoresponse, T-I-V analyses, and interpretation of data in terms of appropriate models to determine key cell parameters. Results of these studies are utilized to determine future approaches for increasing GaAs solar cell efficiencies.

  9. Inverse field-based approach for simultaneous B₁ mapping at high fields - a phantom based study.

    PubMed

    Jin, Jin; Liu, Feng; Zuo, Zhentao; Xue, Rong; Li, Mingyan; Li, Yu; Weber, Ewald; Crozier, Stuart

    2012-04-01

    Based on computational electromagnetics and multi-level optimization, an inverse approach of attaining accurate mapping of both transmit and receive sensitivity of radiofrequency coils is presented. This paper extends our previous study of inverse methods of receptivity mapping at low fields, to allow accurate mapping of RF magnetic fields (B(1)) for high-field applications. Accurate receive sensitivity mapping is essential to image domain parallel imaging methods, such as sensitivity encoding (SENSE), to reconstruct high quality images. Accurate transmit sensitivity mapping will facilitate RF-shimming and parallel transmission techniques that directly address the RF inhomogeneity issue, arguably the most challenging issue of high-field magnetic resonance imaging (MRI). The inverse field-based approach proposed herein is based on computational electromagnetics and iterative optimization. It fits an experimental image to the numerically calculated signal intensity by iteratively optimizing the coil-subject geometry to better resemble the experiments. Accurate transmit and receive sensitivities are derived as intermediate results of the optimization process. The method is validated by imaging studies using homogeneous saline phantom at 7T. A simulation study at 300MHz demonstrates that the proposed method is able to obtain receptivity mapping with errors an order of magnitude less than that of the conventional method. The more accurate receptivity mapping and simultaneously obtained transmit sensitivity mapping could enable artefact-reduced and intensity-corrected image reconstructions. It is hoped that by providing an approach to the accurate mapping of both transmit and receive sensitivity, the proposed method will facilitate a range of applications in high-field MRI and parallel imaging. PMID:22391489

  10. High-precision measurements of global stellar magnetic fields

    NASA Astrophysics Data System (ADS)

    Plachinda, S. I.

    2014-06-01

    This paper presents a brief history of the development of devices and techniques for high-precision measurements of stellar magnetic fields. Two main approaches for the processing of spectral-polarimetric observations are described: the method of least-squares deconvolution (LSD), which is used to find a mean-weighted average of the normalized polarization profile using a set of spectral lines, and a method in which each individual spectral line is used to determine the magnetic field, viz., the single line method (SL). The advantages and disadvantages of the LSD and SL methods are discussed.

  11. Dynamics and structure of self-generated magnetics fields on solids following high contrast, high intensity laser irradiation

    SciTech Connect

    Albertazzi, B.; Chen, S. N.; Fuchs, J.; Antici, P.; Böker, J.; Swantusch, M.; Willi, O.; Borghesi, M.; Breil, J.; Feugeas, J. L.; Nicolaï, Ph.; Tikhonchuk, V. T.; D'Humières, E.; Dervieux, V.; Nakatsutsumi, M.; Romagnagni, L.; Lancia, L.; Shepherd, R.; Sentoku, Y.; Starodubtsev, M.; and others

    2015-12-15

    The dynamics of self-generated magnetic B-fields produced following the interaction of a high contrast, high intensity (I > 10{sup 19 }W cm{sup −2}) laser beam with thin (3 μm thick) solid (Al or Au) targets is investigated experimentally and numerically. Two main sources drive the growth of B-fields on the target surfaces. B-fields are first driven by laser-generated hot electron currents that relax over ∼10–20 ps. Over longer timescales, the hydrodynamic expansion of the bulk of the target into vacuum also generates B-field induced by non-collinear gradients of density and temperature. The laser irradiation of the target front side strongly localizes the energy deposition at the target front, in contrast to the target rear side, which is heated by fast electrons over a much larger area. This induces an asymmetry in the hydrodynamic expansion between the front and rear target surfaces, and consequently the associated B-fields are found strongly asymmetric. The sole long-lasting (>30 ps) B-fields are the ones growing on the target front surface, where they remain of extremely high strength (∼8–10 MG). These B-fields have been recently put by us in practical use for focusing laser-accelerated protons [B. Albertazzi et al., Rev. Sci. Instrum. 86, 043502 (2015)]; here we analyze in detail their dynamics and structure.

  12. Investigations of cosmic ray anisotropies and their relationship to concurrent magnetic field data

    NASA Technical Reports Server (NTRS)

    Allum, F. R.

    1974-01-01

    Investigations of cosmic ray anisotropies and their relationship to concurrent magnetic field data are reported. These investigations range in scope from the examination of data very late in the decay phase of a solar particle event where long term (approximately 6 hour) averages are used and definite interplanetary effects sought after to an examination of the change in low energy particle anisotropy as the satellite approaches the bow shock and the magnetopause.

  13. Investigation Of Vapor Explosion Mechanisms Using High Speed Photography

    NASA Astrophysics Data System (ADS)

    Armstrong, Donn R.; Anderson, Richard P.

    1983-03-01

    The vapor explosion, a physical interaction between hot and cold liquids that causes the explosive vaporization of the cold liquid, is a hazard of concern in such diverse industries as metal smelting and casting, paper manufacture, and nuclear power generation. Intensive work on this problem worldwide, for the past 25 years has generated a number of theories and mechanisms proposed to explain vapor explosions. High speed photography has been the major instrument used to test the validity of the theories and to provide the observations that have lead to new theories. Examples are given of experimental techniques that have been used to investigate vapor explosions. Detailed studies of specific mechanisms have included microsecond flash photograph of contact boiling and high speed cinematography of shock driven breakup of liquid drops. Other studies looked at the explosivity of various liquid pairs using cinematography inside a pulsed nuclear reactor and x-ray cinematography of a thermite-sodium interaction.

  14. Experimental study of the formation of field-reversed configurations employing high-order multipole fields

    NASA Astrophysics Data System (ADS)

    Slough, J. T.; Hoffman, A. L.

    1990-04-01

    A high-order multipole ``barrier'' field was applied at the vacuum tube wall in the TRX experiment [Phys. Fluids B 1, 840 (1989)] during both the preionization and field reversal phases of field-reversed configuration (FRC) formation. Use of this field during field reversal resulted in a significant reduction of impurities as well as increased flux trapping. With a large enough Bθ at the wall, sheath detachment from the wall became apparent, and flux loss through the sheath became negligible (<10%). At larger wall Bθ (>1.5 kG), destructive rotational spin-up occurred, driven by Hall current forces. When the multipole barrier field was also applied during either axial discharge or ringing theta current preionization, a very symmetric and uniform breakdown of the fill gas was achieved. In particular, using ringing theta preionization, complete ionization of the fill gas was accomplished with purely inductive fields of remarkably low magnitude, where Ez≤3 V/cm, and Eθ≤20 V/cm. Due to the improved ionization symmetry, about 65% to 75% of the lift-off flux (flux remaining after field reversal) could be retained through the remaining formation processes into an equilibrium FRC. Using the multipole field during both preionization and formation, it was possible to form FRC's with good confinement with greater than 3 mWb of trapped flux at 15 mTorr D2 or H2 in a 10 cm radius device. Values of s in excess of 4 could be achieved in this manner.

  15. Microencapsulation of Multiple-Layer Emulsion with High-Voltage Electrostatic Field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water-soluble materials are widely used in the applications of agriculture, food and pharmaceuticals. The objective of this study was to investigate a new microencapsulation method to produce water-soluble materials. A high-voltage electrostatic field apparatus was used to produce such materials r...

  16. High-pressure and temperature investigations of energetic materials

    NASA Astrophysics Data System (ADS)

    Gump, J. C.

    2014-05-01

    Static high-pressure measurements are extremely useful for obtaining thermodynamic and phase stability information from a wide variety of materials. However, studying energetic materials can be challenging when extracting information from static high-pressure measurements. Energetic materials are traditionally C, H, N, O compounds with low crystalline symmetry, producing weak signal in commonly performed x-ray diffraction measurements. The small sample volume available in a static high-pressure cell exacerbates this issue. Additionally, typical hydrostatic compression media, such as methanol/ethanol, may react with many energetic materials. However, characterization of their thermodynamic parameters and phase stability is critical to understanding explosive performance and sensitivity. Crystalline properties, such as bulk modulus and thermal expansion, are necessary to accurately predict the behaviour of shocked solids using hydrodynamic codes. In order to obtain these values, equations of state of various energetic materials were investigated using synchrotron angle-dispersive x-ray diffraction experiments at static high-pressure and temperature. Intense synchrotron radiation overcomes the weak x-ray scattering of energetic materials in a pressure cell. The samples were hydrostatically compressed using a non-reactive hydrostatic medium and heated using a heated diamond anvil cell. Pressure - volume data for the materials were fit to the Birch-Murnaghan and Vinet formalisms to obtain bulk modulus and its first pressure derivative. Temperature - volume data at ambient pressure were fit to obtain the volume thermal expansion coefficient. Data from several energetic materials will be presented and compared.

  17. The dynamics of cavitation bubble clouds in high-intensity focused ultrasound field observed by high-speed photography

    NASA Astrophysics Data System (ADS)

    Li, Xiaojing; Chen, Hong; Wan, Mingxi

    2007-01-01

    High-speed photography is being considered as an effective technique to record the transient phenomena in medical field. This presentation summarizes our previous work of using high-speed photography in the observation of cavitation bubble clouds generated in high-intensity focused ultrasound (HIFU) field, aiming at the better understanding of the cavitation mechanism during the medical application of HIFU. A high-speed photography system synchronized with HIFU emission facilities was built up, and using this system we have investigated the dynamics of cavitation bubble clouds (i) in the whole HIFU free field; (ii) in the focal region of HIFU free field; and (iii) near the tissue surface in HIFU field. The spatial-temporal evolution of the bubble cloud and the characteristics of bubble cloud structures as well as the possible explanations to the recorded phenomena are reviewed. All the results we got elucidated that the highspeed camera is a potent tool to detect the cavitation phenomena in HIFU field.

  18. Investigations of diffuse sound fields using systematic changes in surface scattering

    NASA Astrophysics Data System (ADS)

    Herder, John

    Systematically varying the surface scattering in an enclosure provides insight towards the impact of field diffusion on acoustic phenomena. Two independent studies are presented, each utilizing three distinct cases of field diffusion created through the introduction of boundary irregularities. First, dodecaspherical loudspeakers used in acoustic measurement exhibit non-uniform radiation. Also, the interaction of the source sound with room boundaries impacts the degree of energy interference and decay over time. As such, the amount of variation in sound pressure level and clarity over a grid of receivers is investigated with respect to stand-alone cases as well as the promotion of field diffusion. By sequentially expanding the extent of energy mixing in a volume, it is expected that variations in the acoustic parameters over an area will be reduced. Developing a consistent aural experience over a listening area is an important topic in room acoustics, so exploring the physical impact of field diffusion on sound field variance advances this aim. The second experiment reinforces a method for understanding the time arrival of diffuse sound fields in a volume. By systematically promoting greater diffusion, it is expected that the corresponding diffuse sound field will arrive earlier. The turning point property of experimental double sloped energy decays is investigated against a diffusion equation model, relating the valid range of the numerical model to the time onset of the diffuse sound field. In this way, the time arrival of the diffuse sound field is calculated in terms of the change in mean free time between cases. The effect of overall absorption is also discussed, reinforcing the validity of the outcome.

  19. Magnetotelluric investigation in the High Agri Valley (southern Apennine, Italy)

    NASA Astrophysics Data System (ADS)

    Balasco, M.; Giocoli, A.; Piscitelli, S.; Romano, G.; Siniscalchi, A.; Stabile, T. A.; Tripaldi, S.

    2015-04-01

    In this paper we present the result of a magnetotelluric (MT) investigation carried out across the High Agri Valley (HAV), southern Italy. Several MT soundings were carried out in order to obtain a ~15 km long 2-D resistivity model with an investigation depth of ~10 km. The main aim was to provide valuable data on the geological and structural setting of the HAV. The MT model was compared with pre-existing geological, geophysical and seismic data. The MT model can be schematized as a superposition of three stack lateral varying layers with different thickness and resistivity values: a surficial low-medium resistivity layer associated with the Quaternary deposits and to the allochthonous units; and a deeper high resistivity layer related to the Apulia Platform, separated by a thin layer connected to the mélange zone and to the Pliocene terrigenous marine deposits. Sharp lateral resistivity variations are interpreted as faults that, on the basis of accurate focal mechanism computations, display normal-faulting kinematics.

  20. Magnetotelluric investigation in the High Agri Valley (southern Apennine, Italy)

    NASA Astrophysics Data System (ADS)

    Balasco, M.; Giocoli, A.; Piscitelli, S.; Romano, G.; Siniscalchi, A.; Stabile, T. A.; Tripladi, S.

    2014-11-01

    In this paper we present the result of a Magnetotelluric (MT) investigation carried out across the High Agri Valley (HAV), southern Italy. Several MT soundings were carried out in order to obtain a ~15 km long 2-D resistivity model with an investigation depth of ~10 km. The main aim was to provide valuable data on the geological and structural setting of the HAV. The MT model was compared with pre-existing geological, geophysical and seismic data. The MT model can be schematized as a superposition of three stack lateral varying layers with different thickness and resistivity values: a surficial low-medium resistivity layer, associated to the Quaternary deposits and to the allochthonous units, and a deeper high resistivity layer, related to the Apulia Platform, separated by a thin layer connected to the mélange zone and to the Pliocene terrigenous marine deposits. Sharp lateral resistivity variations are interpreted as faults that, on the basis of accurate focal mechanism computations, display normal-faulting kinematics.

  1. Characterization and manipulation of a high-magnetic field trap

    NASA Astrophysics Data System (ADS)

    Paradis, Eric; Raithel, Georg

    2012-06-01

    We report on the characterization of an efficient atom trap within a background magnetic field of 2.6 Tesla. Up to 10̂8 Rubidium atoms are recaptured from a cold atomic beam with a 2-3% collection efficiency, in a cigar-shaped volume and cooled with a six-beam optical molasses. The aspect ratio of the trap is measured as a function of the magnetic field curvature, which can be varied to produce a range of trap shapes. The trapping lineshape is both narrow and asymmetric, as is characteristic of laser-cooling of atoms or ions in an external trapping potential. Additional features of the high magnetic field trap include cooling onto hollow shell-like structures. Simulation results are also presented.

  2. 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.

  3. Control and data acquisition systems for high field superconducting wigglers

    NASA Astrophysics Data System (ADS)

    Batrakov, A.; Ilyin, I.; Karpov, G.; Kozak, V.; Kuzin, M.; Kuper, E.; Mamkin, V.; Mezentsev, N.; Repkov, V.; Selivanov, A.; Shkaruba, V.

    2001-07-01

    This paper describes the control and DAQ system of superconducting wigglers with magnetic field range up to 10.3 T. The first version of the system controls a 7 T superconducting wiggler prepared for installation at Bessy-II (Germany). The second one controls a 10 T wiggler which is under testing now at the SPring-8 site (Japan). Both systems are based on VME apparatus. The set of specialized VME modules is elaborated to arrange wiggler power supply control, full time wiggler monitoring, and magnetic field high accuracy measurement and field stabilization. The software for the control of the wigglers is written in C language for VxWorks operation system for a Motorola-162 VME controller. The task initialization, stops and acquisition of the data can be done from the nearest personal computer (FTP host for VME), or from the remote system as well.

  4. Rf Gun with High-Current Density Field Emission Cathode

    SciTech Connect

    Jay L. Hirshfield

    2005-12-19

    High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes

  5. Wide-field high-performance geosynchronous imaging

    NASA Astrophysics Data System (ADS)

    Wood, H. John; Jenstrom, Del; Wilson, Mark; Hinkal, Sanford; Kirchman, Frank

    1998-01-01

    The NASA Mission to Planet Earth (MTPE) Program and the National Oceanographic and Atmospheric Administration (NOAA) are sponsoring the Advanced Geosynchronous Studies (AGS) to develop technologies and system concepts for Earth observation from geosynchronous orbit. This series of studies is intended to benefit both MTPE science and the NOAA GOES Program. Within the AGS program, advanced imager trade studies have investigated two candidate concepts for near-term advanced geosynchronous imagers. One concept uses a scan mirror to direct the line of sight from a 3-axis stabilized platform. Another eliminates the need for a scan mirror by using an agile spacecraft bus to scan the entire instrument. The purpose of this paper is to discuss the optical design trades and system issues encountered in evaluating the two scanning approaches. The imager design started with a look at first principles: what is the most efficient way to image the Earth in those numerous spectral bands of interest to MTPE scientists and NOAA weather forecasters. Optical design trades included rotating filter wheels and dispersive grating instruments. The design converged on a bandpass filter instrument using four focal planes to cover the spectral range 0.45 to 13.0 micrometers. The first imager design uses a small agile spacecraft supporting an afocal optical telescope. Dichroic beamsplitters feed refractive objectives to four focal planes. The detectors are a series of long linear and rectangular arrays which are scanned in a raster fashion over the 17 degree Earth image. The use of the spacecraft attitude control system to raster the imager field-of-view (FOV) back and forth over the Earth eliminates the need for a scan mirror. However, the price paid is significant energy and time required to reverse the spacecraft slew motions at the end of each scan line. Hence, it is desired to minimize the number of scan lines needed to cover the full Earth disk. This desire, coupled with the ground

  6. Wide-field high-performance geosynchronous imaging

    SciTech Connect

    Wood, H. John; Jenstrom, Del; Wilson, Mark; Hinkal, Sanford; Kirchman, Frank

    1998-01-15

    The NASA Mission to Planet Earth (MTPE) Program and the National Oceanographic and Atmospheric Administration (NOAA) are sponsoring the Advanced Geosynchronous Studies (AGS) to develop technologies and system concepts for Earth observation from geosynchronous orbit. This series of studies is intended to benefit both MTPE science and the NOAA GOES Program. Within the AGS program, advanced imager trade studies have investigated two candidate concepts for near-term advanced geosynchronous imagers. One concept uses a scan mirror to direct the line of sight from a 3-axis stabilized platform. Another eliminates the need for a scan mirror by using an agile spacecraft bus to scan the entire instrument. The purpose of this paper is to discuss the optical design trades and system issues encountered in evaluating the two scanning approaches. The imager design started with a look at first principles: what is the most efficient way to image the Earth in those numerous spectral bands of interest to MTPE scientists and NOAA weather forecasters. Optical design trades included rotating filter wheels and dispersive grating instruments. The design converged on a bandpass filter instrument using four focal planes to cover the spectral range 0.45 to 13.0 micrometers. The first imager design uses a small agile spacecraft supporting an afocal optical telescope. Dichroic beamsplitters feed refractive objectives to four focal planes. The detectors are a series of long linear and rectangular arrays which are scanned in a raster fashion over the 17 degree Earth image. The use of the spacecraft attitude control system to raster the imager field-of-view (FOV) back and forth over the Earth eliminates the need for a scan mirror. However, the price paid is significant energy and time required to reverse the spacecraft slew motions at the end of each scan line. Hence, it is desired to minimize the number of scan lines needed to cover the full Earth disk. This desire, coupled with the ground

  7. 77 FR 16852 - Notice of Reclassification of Five Regional Offices to Investigative Field Offices: Seattle, WA...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-22

    ... Central Islip, New York, sub-field office of investigations. SUMMARY: This notice advises the public that.... (d) Space alteration costs (de minimus). Some offices may require space alterations and telephone changes to accommodate any future changes of assigned staff. However, HUD/OIG estimates that any...

  8. Field Investigations of Lactate-Stimulated Bioreduction of Cr(VI) at Hanford 100H

    SciTech Connect

    T. C. Hazen; B. Faybishenko; D. Joyner; S. Borglin; E. Brodie; S. Hubbard; K. Williams; J. Peterson; J. Wan; T. Tokunaga; M. Firestone; P. E. Long; Resch, C.T.; Newcomer, D.; Koenigsberg, S.; Willet, A. C. T. Resch, and D. Newcomer , S. Koenigsberg and A. Willet Field Investigations of Lactate-Stimulated Bioreduction of Cr at Hanford 100H

    2005-04-20

    The overall objective of this paper is to carry out field investigations to assess the potential for immobilizing and detoxifying chromium-contaminated groundwater using lactate-stimulated bioreduction of Cr(VI) to Cr(III) at the Hanford 100H site.

  9. Release and fate of fluorocarbons in a shredder residue landfill cell: 2. Field investigations.

    PubMed

    Scheutz, Charlotte; Fredenslund, Anders M; Nedenskov, Jonas; Kjeldsen, Peter

    2010-11-01

    The shredder residues from automobiles, home appliances and other metal containing products are often disposed in landfills, as recycling technologies for these materials are not common in many countries. Shredder waste contains rigid and soft foams from cushions and insulation panels blown with fluorocarbons. The objective of this study was to determine the gas composition, attenuation, and emission of fluorocarbons in a monofill shredder residue landfill cell by field investigation. Landfill gas generated within the shredder waste primarily consisted of CH(4) (27%) and N(2) (71%), without CO(2), indicating that the gas composition was governed by chemical reactions in combination with anaerobic microbial reactions. The gas generated also contained different fluorocarbons (up to 27 μg L(-1)). The presence of HCFC-21 and HCFC-31 indicated that anaerobic degradation of CFC-11 occurred in the landfill cell, as neither of these compounds has been produced for industrial applications. This study demonstrates that a landfill cell containing shredder waste has a potential for attenuating CFC-11 released from polyurethane (PUR) insulation foam in the cell via aerobic and anaerobic biodegradation processes. In deeper, anaerobic zones of the cell, reductive dechlorination of CFCs to HCFCs was evident, while in the shallow, oxic zones, there was a high potential for biooxidation of both methane and lesser chlorinated fluorocarbons. These findings correlated well with both laboratory results (presented in a companion paper) and surface emission measurements that, with the exception from a few hot spots, indicated that surface emissions were negative or below detection. PMID:20444588

  10. Investigation of mechanical field weakening of axial flux permanent magnet motor

    NASA Astrophysics Data System (ADS)

    Syaifuddin Mohd, M.; Aziz, A. Rashid A.; Syafiq Mohd, M.

    2015-12-01

    An investigation of axial flux permanent magnet motor (AFPM) characteristics was conducted with a proposed mechanical field weakening control mechanisms (by means of stator-rotor force manipulation) on the motor through modeling and experimentation. By varying the air gap between at least two bistable positions, the peak torque and top speed of the motor can be extended. The motor high efficiency region can also be extended to cover greater part of the motor operating points. An analytical model of the motor had been developed to study the correlation between the total attraction force (between the rotor and the stator) and the operating parameters of the motor. The test results shows that the motor output complies with the prediction of the research hypothesis and it is likely that a spring locking mechanism can be built to dynamically adjust the air gap of the motor to increase the operating range and could be applied in electric drivetrain applications to improve overall efficiency of electric and hybrid electric vehicles.

  11. Investigation of protein detection parameters using nanofunctionalized organic field-effect transistors.

    PubMed

    Hammock, Mallory L; Knopfmacher, Oren; Naab, Benjamin D; Tok, Jeffrey B-H; Bao, Zhenan

    2013-05-28

    Biodetection using organic field-effect transistors (OFETs) is gaining increasing interest for applications as diverse as food security, environmental monitoring, and medical diagnostics. However, there still lacks a comprehensive, empirical study on the fundamental limits of OFET sensors. In this paper, we present a thorough study of the various parameters affecting biosensing using an OFET decorated with gold nanoparticle (AuNP) binding sites. These parameters include the spacing between receptors, pH of the buffer, and ionic strength of the buffer. To this end, we employed the thrombin protein and its corresponding DNA binding aptamer to form our model detection system. We demonstrate a detection limit of 100 pM for this protein with high selectivity over other proteases in situ. We describe herein a feasible approach for protein detection with OFETs and a thorough investigation of parameters governing biodetection events using OFETs. Our obtained results should provide important guidelines to tailor the sensor's dynamic range to suit other desired OFET-based biodetection applications. PMID:23597051

  12. New insights into rotating frame relaxation at high field.

    PubMed

    Spear, John T; Gore, John C

    2016-09-01

    Measurements of spin-lock relaxation rates in the rotating frame (R1ρ ) at high magnetic fields afford the ability to probe not only relatively slow molecular motions, but also other dynamic processes, such as chemical exchange and diffusion. In particular, measurements of the variation (or dispersion) of R1ρ with locking field allow the derivation of quantitative parameters that describe these processes. Measurements in deuterated solutions demonstrate the manner and degree to which exchange dominates relaxation at high fields (4.7 T, 7 T) in simple solutions, whereas temperature and pH are shown to be very influential factors affecting the rates of proton exchange. Simulations and experiments show that multiple exchanging pools of protons in realistic tissues can be assumed to behave independently of each other. R1ρ measurements can be combined to derive an exchange rate contrast (ERC) that produces images whose intensities emphasize protons with specific exchange rates rather than chemical shifts. In addition, water diffusion in the presence of intrinsic susceptibility gradients may produce significant effects on R1ρ dispersions at high fields. The exchange and diffusion effects act independently of each other, as confirmed by simulation and experimentally in studies of red blood cells at different levels of oxygenation. Collectively, R1ρ measurements provide an ability to quantify exchange processes, to provide images that depict protons with specific exchange rates and to describe the microstructure of tissues containing magnetic inhomogeneities. As such, they complement traditional T1 or T2 measurements and provide additional insights from measurements of R1ρ at a single locking field. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26866422

  13. Investigating microbial transformations of soil organic matter: synthesizing knowledge from disparate fields to guide new experimentation

    NASA Astrophysics Data System (ADS)

    Billings, S. A.; Tiemann, L. K.; Ballantyne, F., IV; Lehmeier, C.; Min, K.

    2014-12-01

    Investigators of soil organic matter (SOM) transformations struggle with a deceptively simple-sounding question: "Why does some SOM leave the soil profile relatively quickly, while other compounds, especially those at depth, appear to be retained on timescales ranging from the decadal to the millennial?" This question is important on both practical and academic levels, but addressing it is challenging for a multitude of reasons. Simultaneous with soil-specific advances, multiple other disciplines have enhanced their knowledge bases in ways potentially useful for future investigations of SOM decay. In this article, we highlight observations highly relevant for those investigating SOM decay and retention but often emanating from disparate fields and residing in literature seldom cited in SOM research. We focus on recent work in two key areas. First, we turn to experimental approaches using natural and artificial aquatic environments to investigate patterns of microbially-mediated OM transformations as environmental conditions change, and highlight how aquatic microbial responses to environmental change can reveal processes likely important to OM decay and retention in soils. Second, we emphasize the importance of establishing intrinsic patterns of decay kinetics for purified substrates commonly found in soils to develop baseline rates. These decay kinetics - which represent the upper limit of the reaction rates - can then be compared to substrate decay kinetics observed in natural samples, which integrate intrinsic decay reaction rates and edaphic factors essential to the site under study but absent in purified systems. That comparison permits the site-specific factors to be parsed from the fundamental decay kinetics, an important advance in our understanding of SOM decay (and thus persistence) in natural systems. We then suggest ways in which empirical observations from aquatic systems and purified enzyme-substrate reaction kinetics can be used to advance recent

  14. Field Investigation of a New Recharge Approach for ASR Projects in Near-Surface Aquifers.

    PubMed

    Liu, Gaisheng; Knobbe, Steven; Reboulet, Edward C; Whittemore, Donald O; Händel, Falk; Butler, James J

    2016-05-01

    Aquifer storage and recovery (ASR) is the artificial recharge and temporary storage of water in an aquifer when water is abundant, and recovery of all or a portion of that water when it is needed. One key limiting factor that still hinders the effectiveness of ASR is the high costs of constructing, maintaining, and operating the artificial recharge systems. Here we investigate a new recharge method for ASR in near-surface unconsolidated aquifers that uses small-diameter, low-cost wells installed with direct-push (DP) technology. The effectiveness of a DP well for ASR recharge is compared with that of a surface infiltration basin at a field site in north-central Kansas. The performance of the surface basin was poor at the site due to the presence of a shallow continuous clay layer, identified with DP profiling methods, that constrained the downward movement of infiltrated water and significantly reduced the basin recharge capacity. The DP well penetrated through this clay layer and was able to recharge water by gravity alone at a much higher rate. Most importantly, the costs of the DP well, including both the construction and land costs, were only a small fraction of those for the infiltration basin. This low-cost approach could significantly expand the applicability of ASR as a water resources management tool to entities with limited fiscal resources, such as many small municipalities and rural communities. The results of this investigation demonstrate the great potential of DP wells as a new recharge option for ASR projects in near-surface unconsolidated aquifers. PMID:26313764

  15. Graded High Field Nb3Sn Dipole Magnets

    SciTech Connect

    Caspi, S.; Ferracin, P.; Gourlay, S.

    2007-06-01

    Dipole magnets with fields beyond 16T will require superconducting coils that are at least 40 mm thick, an applied pres-stress around 150 MPa and a protection scheme for stored energy in the range of 1-2 MJ/m. The coil size will have a direct impact on the overall magnet cost and the stored energy will raise new questions on protection. To reduce coil size and minimize risk, the coil may have to be graded. Grading is achieved by splitting the coil into several layers with current densities that match the short sample field in each layer. Grading, especially at high fields, can be effective; however it will also significantly raise the stress. In this paper we report on the results of a study on the coil size and field relation to that of the stress and stored energy. We then extend the results to graded coils and attempt to address high stress issues and ways to reduce it.

  16. Dissociation Dynamics of Molecular Ions in High dc Electric Field.

    PubMed

    Blum, Ivan; Rigutti, Lorenzo; Vurpillot, François; Vella, Angela; Gaillard, Aurore; Deconihout, Bernard

    2016-05-26

    In an atom probe, molecular ions can be field evaporated from the analyzed material and, then, can dissociate under the very intense electric field close to the field emitter. In this work, field evaporation of ZnO reveals the emission of Zn2O2(2+) ions and their dissociation into ZnO(+) ions. It is shown that the repulsion between the produced ZnO(+) ions is large enough to have a measurable effect on both the ion trajectories and times of flight. Comparison with numerical simulations of the ion trajectories gives information on the lifetime of the parent ions, the energy released by the dissociation and repulsion, and also the dissociation direction. This study not only opens the way to a new method to obtain information on the behavior of molecular ions in high electric fields by using an atom probe, but also opens up the interesting perspective to apply this technique to a wide class of materials and molecules. PMID:27136453

  17. Investigation of flow and solute transport at the field scale through heterogeneous deformable porous media

    NASA Astrophysics Data System (ADS)

    Chang, Ching-Min; Yeh, Hund-Der

    2016-09-01

    This work describes an investigation of the spatial statistical structure of specific discharge field and solute transport process of a nonreactive solute at the field scale through a heterogeneous deformable porous medium. The flow field is driven by a vertical gradient in the excess pore water pressure induced by a step increase in load applied on the upper part of a finite-thickness aquifer. The non-stationary spectral representation is adopted to characterize the spatial covariance of the specific discharge field necessary for the development of the solute particle trajectory statistics using the Lagrangian formalism. We show that the statistics of the specific discharge and particle trajectory derived herein are non-stationary and functions of the coefficient of soil compressibility, μ. The effect of μ on the relative variation of specific discharge and the solute particle trajectory statistics are analyzed upon evaluating our expressions.

  18. Investigation of the pressure and velocity fields in a turbulent separated flow using the LES technique

    NASA Astrophysics Data System (ADS)

    Arnal, M.; Friedrich, R.

    1991-01-01

    The large eddy simulation (LES) technique is utilized to investigate the turbulent separating and reattaching flow over a rearward-facing step. Simulations on a series of successively refined grids were performed (maximum resolution: 320 x 64 x 48). Statistical results are compared with experimental data and show good agreement. An examination of the simulated flow fields reveals the instantaneous structure of the separating shear layer, the reattachment zone and the recirculation region. Large departures from the mean in both the velocity and pressure fields are found to occur in all three regions. The shape and size of structures in the velocity and pressure fields varies with the proximity of solid walls and the region of the flow domain. Awareness of the instantaneous flow field structure is shown to be instrumental to having a complete understanding of the unsteady turbulent flow.

  19. An experimental investigation of the flow field of a rectangular wall jet

    NASA Technical Reports Server (NTRS)

    Horne, C.; Karamcheti, K.

    1979-01-01

    The structure of a laminar, rectangular wall jet developing from an initially parabolic velocity profile was investigated with measurements of the mean and fluctuating velocity field, and with Schlieren flow visualization. The effects on mean and fluctuating velocity fields of changes in the jet Reynolds number over the range of from 0 to 4800, and of various wall lengths ranging from 0 to 312 jet widths were studied. For a given wall length and Reynolds number, disturbances in the flow field were regular and periodic, and of a constant frequency in a large region of the flow field. Small, self-excited disturbances at the nozzle exit were observed to grow exponentially with downstream distance, and roll up to form a convecting array of discrete vortices. For certain values of wall length and jet speed, discrete audible tones were detected, and appeared to be associated with an enhancement of the regularity and stability of the vortex array.

  20. Electric-field induced mutation of DNA: a theoretical investigation of the GC base pair.

    PubMed

    Cerón-Carrasco, José P; Jacquemin, Denis

    2013-04-01

    It is known that intense external electric fields affect the proton transfer (PT) reactions in simple chemical systems, such as hydrated chlorhydric acid or formic acid dimer. Accordingly, electric fields might be used to modulate the PT reactions responsible for the spontaneous mutation mechanism in DNA. In this contribution, we investigate the effect of these fields on the tautomeric equilibria of the guanine-cytosine (GC) base pair in order to gain further insight into this hypothesis. This task is performed with both density functional theory (DFT) and second-order Møller-Plesset (MP2) approaches. Our results demonstrate that electric fields not only drastically alter the rate constants of PT but also tune the mechanism of the PT reactions in the GC base pair. PMID:23338206

  1. Cathode driven high gain crossed-field amplifier

    NASA Astrophysics Data System (ADS)

    1983-07-01

    The objective of this three-phase program is to achieve the design of a cathode driven high gain re-entrant Crossed Field Amplifier capable of meeting the parameters of Raytheon Company specification No. 968838 dated 10 May 1978. The effort includes the fabrication and test of three developmental and four final configuration tubes. One final configuration tube will be life tested and two will be delivered to the Navy. The tasks discussed during this report period relate to the cold tests performed on various subassemblies of model no. 4 and on the sealed-in model no. 4 of the S-band high gain cathode driven crossed field amplifier. Based on the performance of model no. 3 certain remedial measures have been implemented in model no. 4 that have resulted in the elimination of key resonances within the tube and an improvement in the isolation between the cathode and anode circuits.

  2. Metabolite quantification and high-field MRS in breast cancer

    PubMed Central

    Haddadin, Ihab S.; McIntosh, Adeka; Meisamy, Sina; Corum, Curt; Styczynski Snyder, Angela L.; Powell, Nathaniel J.; Nelson, Michael T.; Yee, Douglas; Garwood, Michael; Bolan, Patrick J.

    2008-01-01

    In vivo 1H MRS is rapidly developing as a clinical tool for diagnosing and characterizing breast cancers. Many in vivo and in vitro experiments have demonstrated that alterations in concentrations of choline-containing metabolites are associated with malignant transformation. In recent years, considerable efforts have been made to evaluate the role of 1H MRS measurements of total choline-containing compounds in the management of patients with breast cancer. Current technological developments, including the use of high-field MR scanners and quantitative spectroscopic analysis methods, promise to increase the sensitivity and accuracy of breast MRS. This article reviews the literature describing in vivo MRS in breast cancer, with an emphasis on the development of high-field MR scanning and quantitative methods. Potential applications of these technologies for diagnosing suspicious lesions and monitoring response to chemotherapy are discussed. PMID:17957820

  3. Sudden flux change studies in high field superconducting accelerator magnets

    SciTech Connect

    Feher, S.; Bordini, B.; Carcagno, R.; Makulski, A.; Orris, D.F.; Pischalnikov, Y.M.; Sylvester, C.; Tartaglia, M.; Tompkins, J.C.; Zlobin, A.V.; /Fermilab

    2004-10-01

    As part of the High Field Magnet Program at Fermilab many magnets have been tested which utilize multi strand Rutherford type cable made of state-of-the art Nb{sub 3}Sn strands. During these magnet tests we observed sudden flux changes by monitoring coil voltages and the magnetic field close to the magnets. These flux changes might be linked to magnet instabilities. The voltage spike signals were correlated with quench antenna signals, a strong indication that these are magnet phenomena. With a new high resolution voltage spike detection system, we were able to observe the detailed structure of the spikes. Two fundamentally different signal shapes were distinguished, most likely generated by different mechanisms.

  4. Magnetic susceptibilities of V3+ in corundum: Magnetic anisotropy at high fields

    NASA Astrophysics Data System (ADS)

    Brumage, William H.; Quade, C. Richard; Dorman, C. Franklin

    1995-08-01

    We theoretically investigate the behavior of the V3+ ion as an impurity in Al2O3 under high magnetic fields, up to 20 T. In particular, we investigate the introduction of magnetic anisotropy that is lower than the trigonal symmetry of the host crystal. Two approaches are used for the calculations. First, fourth-order perturbation theory is used to develop quartic terms plus one sextic term in the susceptibility tensor that are good for fields up to 4 T. Then, the three-level energy matrix is reduced exactly to obtain the anisotropy at higher fields. It is found that the dominant contributions to the magnetic-induced anisotropy arise from the χxxxx term, while the χxxzz=χzxxz, χzzzz, and the χxxxxxx terms give a much lower contribution. Temperature-dependent effects are reported. There is a very small dependence of the magnetization upon the zero-field splitting.

  5. Investigation of superparamagnetic (Fe3O4) nanoparticles and magnetic field exposures on CHO-K1 cell line

    NASA Astrophysics Data System (ADS)

    Coker, Zachary; Estlack, Larry; Hussain, Saber; Choi, Tae-Youl; Ibey, Bennett L.

    2016-03-01

    Rapid development in nanomaterial synthesis and functionalization has led to advanced studies in actuation and manipulation of cellular functions for biomedical applications. Often these actuation techniques employ externally applied magnetic fields to manipulate magnetic nanomaterials inside cell bodies in order to drive or trigger desired effects. While cellular interactions with low-frequency magnetic fields and nanoparticles have been extensively studied, the fundamental mechanisms behind these interactions remain poorly understood. Additionally, modern investigations on these concurrent exposure conditions have been limited in scope, and difficult to reproduce. This study presents an easily reproducible method of investigating the biological impact of concurrent magnetic field and nanoparticle exposure conditions using an in-vitro CHO-K1 cell line model, with the purpose of establishing grounds for in-depth fundamental studies of the mechanisms driving cellular-level interactions. Cells were cultured under various nanoparticle and magnetic field exposure conditions from 0 to 500 μg/ml nanoparticle concentrations, and DC, 50 Hz, or 100 Hz magnetic fields with 2.0 mT flux density. Cells were then observed by confocal fluorescence microscopy, and subject to biological assays to determine the effects of concurrent extreme-low frequency magnetic field and nanoparticle exposures on cellnanoparticle interactions, such as particle uptake and cell viability by MTT assay. Current results indicate little to no variation in effect on cell cultures based on magnetic field parameters alone; however, it is clear that deleterious synergistic effects of concurrent exposure conditions exist based on a significant decrease in cell viability when exposed to high concentrations of nanoparticles and concurrent magnetic field.

  6. Experimental Investigation of High Temperature Superconducting Imaging Surface Magnetometry

    SciTech Connect

    Espy, M.A.; Matlachov, A.N.; Kraus, R.H., Jr.

    1999-06-21

    The behavior of high temperature superconducting quantum interference devices (SQUIDs) in the presence of high temperature superconducting surfaces has been investigated. When current sources are placed close to a superconducting imaging surface (SIS) an image current is produced due to the Meissner effect. When a SQUID magnetometer is placed near such a surface it will perform in a gradiometric fashion provided the SQUID and source distances to the SIS are much less than the size of the SIS. We present the first ever experimental verification of this effect for a high temperature SIS. Results are presented for two SQUID-SIS configurations, using a 100 mm diameter YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} disc as the SIS. These results indicate that when the current source and sensor coil (SQUID) are close to the SIS, the behavior is that of a first-order gradiometer. The results are compared to analytic solutions as well as the theoretical predictions of a finite element model.

  7. High pressure apparatus for transport properties study in high magnetic field

    SciTech Connect

    Alsmadi, A. M.; Nakotte, H.; Honda, F.; Sechovsky, V.; Mikulina, O.; Kamarad, J.; Lacerda, A. H.

    2002-01-01

    We have designed a high pressure apparatus for measuring electrical-transport properties at low temperatures, high magnetic field and hydrostatic pressure up to 10 kbar. Details of the high-pressure cell and an exemplary study on UNiAI are described and discussed briefly.

  8. Numerical Investigation of High Velocity Suspension Flame Spraying

    NASA Astrophysics Data System (ADS)

    Taleby, M.; Hossainpour, S.

    2012-12-01

    High-velocity suspension flame spraying (HVSFS) has recently developed as a possible alternative to conventional HVOF-spraying employing liquid suspensions instead of dry powder feedstock enables the use of nanoparticles. From the fluid dynamics point of view, the HVSFS system is complex and involves three-phase (gas, liquid and solid particles) turbulent flow, heat transfer, evaporation of the suspension solvent, chemical reactions of main fuel (propane) and suspension solvent (ethanol) and supersonic/subsonic flow transitions. Computational fluid dynamic techniques were carried out to solve the mass, momentum, and energy conservation equations. The realizable k-ɛ turbulence model was used to account for the effect of turbulence. The HVSFS process involves two combustion reactions. A primary combustion process is the premixed oxygen-propane reaction and secondary process is the non-premixed oxygen-gaseous ethanol reaction. For each reaction, one step global reaction, which takes dissociations and intermediate reactions into account, was derived from the equilibrium chemistry code developed by Gordon and McBride and eddy dissipation model was used to calculate the rate of reactions based on the transport equations for all species (10 species) mass fractions. Droplets were tracked in the continuum in a Lagrangian approach. In this paper, flow field inside and outside the gun simulated to provide clear and complete insight about the HVSFS processes. Moreover, the effect of some operative parameters (oxy-fuel flow rate, ethanol flow rate, droplets injection velocity and droplets size) on the gas flow field along the centerline and droplets evaporation behavior was discussed.

  9. Consistent interactions for high-spin fermion fields

    NASA Astrophysics Data System (ADS)

    Vrancx, Tom; de Cruz, Lesley; Ryckebusch, Jan; Vancraeyveld, Pieter

    2011-10-01

    We address the issue of consistent interactions for off-shell fermion fields of arbitrary spin. These interactions play a crucial role in the quantum hadrodynamical description of high-spin baryon resonances in hadronic processes. The Rarita-Schwinger (R-S) description of high-spin fermion fields involves unphysical degrees of freedom associated with their lower-spin content. These enter the interaction if not eliminated outright. The invariance condition of the interaction under the unconstrained R-S gauge removes the lower-spin content of the fermion propagator and leads to a consistent description of the interaction. We develop the most general consistent interaction structure for high-spin fermions. We find that the power of the momentum dependence of a consistent interaction rises with the spin of the fermion field. This leads to unphysical structures in the energy dependence of the computed tree-level cross sections when the short-distance physics is cut off with standard hadronic form factors. A spin-dependent hadronic form factor is proposed that suppresses the unphysical artifacts.

  10. Geophysical Properties of Hard Rock for Investigation of Stress Fields in Deep Mines

    NASA Astrophysics Data System (ADS)

    Tibbo, M.; Young, R. P.; Schmitt, D. R.; Milkereit, B.

    2014-12-01

    A complication in geophysical monitoring of deep mines is the high-stress dependency of the physical properties of hard rocks. In-mine observations show anisotropic variability of the in situ P- and S-wave velocities and resistivity of the hard rocks that are likely related to stress field changes. As part of a comprehensive study in a deep, highly stressed mine located in Sudbury, Ontario, Canada, data from in situ monitoring of the seismicity, conductivity, stress, and stress dependent physical properties has been obtain. In-laboratory experiments are also being performed on borehole cores from the Sudbury mines. These experiments will measure the Norite borehole core's properties including elastic modulus, bulk modulus, P- and S-wave velocities, and density. Hydraulic fracturing has been successfully implemented in industries such as oil and gas and enhanced geothermal systems, and is currently being investigated as a potential method for preconditioning in mining. However, further research is required to quantify how hydraulic fractures propagate through hard, unfractured rock as well as naturally fractured rock typically found in mines. These in laboratory experiments will contribute to a hydraulic fracturing project evaluating the feasibility and effectiveness of hydraulic fracturing as a method of de-stressing hard rock mines. A tri-axial deformation cell equipped with 18 Acoustic Emission (AE) sensors will be used to bring the borehole cores to a tri-axial state of stress. The cores will then be injected with fluid until the the hydraulic fracture has propagated to the edge of the core, while AE waveforms will be digitized continuously at 10 MHz and 12-bit resolution for the duration of each experiment. These laboratory hydraulic fracture experiments will contribute to understanding how parameters including stress ratio, fluid injection rate, and viscosity, affect the fracturing process.

  11. Development of low temperature and high magnetic field X-ray diffraction facility

    NASA Astrophysics Data System (ADS)

    Shahee, Aga; Sharma, Shivani; Singh, K.; Lalla, N. P.; Chaddah, P.

    2015-06-01

    The current progress of materials science regarding multifunctional materials (MFM) has put forward the challenges to understand the microscopic origin of their properties. Most of such MFMs have magneto-elastic correlations. To investigate the underlying mechanism it is therefore essential to investigate the structural properties in the presence of magnetic field. Keeping this in view low temperature and high magnetic field (LTHM) powder x-ray diffraction (XRD), a unique state-of-art facility in the country has been developed at CSR Indore. This setup works on symmetric Bragg Brentano geometry using a parallel incident x-ray beam from a rotating anode source working at 17 kW. Using this one can do structural studies at non-ambient conditions i.e. at low- temperatures (2-300 K) and high magnetic field (+8 to -8 T). The available scattering angle ranges from 5° to 115° 2θ with a resolution better than 0.1°. The proper functioning of the setup has been checked using Si sample. The effect of magnetic field on the structural properties has been demonstrated on Pr0.5Sr0.5MnO3 sample. Clear effect of field induced phase transition has been observed. Moreover, the effect of zero field cooled and field cooled conditions is also observed.

  12. Development of low temperature and high magnetic field X-ray diffraction facility

    SciTech Connect

    Shahee, Aga; Sharma, Shivani; Singh, K.; Lalla, N. P. Chaddah, P.

    2015-06-24

    The current progress of materials science regarding multifunctional materials (MFM) has put forward the challenges to understand the microscopic origin of their properties. Most of such MFMs have magneto-elastic correlations. To investigate the underlying mechanism it is therefore essential to investigate the structural properties in the presence of magnetic field. Keeping this in view low temperature and high magnetic field (LTHM) powder x-ray diffraction (XRD), a unique state-of-art facility in the country has been developed at CSR Indore. This setup works on symmetric Bragg Brentano geometry using a parallel incident x-ray beam from a rotating anode source working at 17 kW. Using this one can do structural studies at non-ambient conditions i.e. at low- temperatures (2-300 K) and high magnetic field (+8 to −8 T). The available scattering angle ranges from 5° to 115° 2θ with a resolution better than 0.1°. The proper functioning of the setup has been checked using Si sample. The effect of magnetic field on the structural properties has been demonstrated on Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} sample. Clear effect of field induced phase transition has been observed. Moreover, the effect of zero field cooled and field cooled conditions is also observed.

  13. Quasi permanent superconducting magnet of very high field

    NASA Technical Reports Server (NTRS)

    Ren, Y.; Liu, J.; Weinstein, R.; Chen, I. G.; Parks, D.; Xu, J.; Obot, V.; Foster, C.

    1993-01-01

    We report on persistent field in a quasi-permanent magnet made of high temperature superconductor. The material has an average of 40 percent molar excess of Y, relative to Y1Ba2Cu3O7 and has been irradiated with high energy light ions at 200 MeV. The magnet, which traps 1.52 T at 77.3 K, traps nearly 4 T at 64.5 K. No evidence of giant flux jump or sample cracking was observed.

  14. A high efficiency annular dark field detector for STEM.

    PubMed

    Kirkland, E J; Thomas, M G

    1996-01-01

    A new high efficiency annular dark field (ADF) detector for an HB501 STEM (Scanning Transmission Electron Microscope) has been constructed and tested. This detector uses a single crystal YAP scintillator and a solid quartz light pipe extending from the scintillator (inside the vacuum) to the photomultiplier tube (outside the vacuum). A factor of approximately 100 improvement in signal relative to the original detector has been obtained. This has substantially improved the signal to noise ratio in the recorded high resolution ADF-STEM images. PMID:22666919

  15. The Mechanical Design Optimization of a High Field HTS Solenoid

    SciTech Connect

    Lalitha, SL; Gupta, RC

    2015-06-01

    This paper describes the conceptual design optimization of a large aperture, high field (24 T at 4 K) solenoid for a 1.7 MJ superconducting magnetic energy storage device. The magnet is designed to be built entirely of second generation (2G) high temperature superconductor tape with excellent electrical and mechanical properties at the cryogenic temperatures. The critical parameters that govern the magnet performance are examined in detail through a multiphysics approach using ANSYS software. The analysis results formed the basis for the performance specification as well as the construction of the magnet.

  16. Density limits investigation and high density operation in EAST tokamak

    NASA Astrophysics Data System (ADS)

    Zheng, Xingwei; Li, Jiangang; Hu, Jiansheng; Liu, Haiqing; Jie, Yinxian; Wang, Shouxin; Li, Jiahong; Duan, Yanming; Li, Miaohui; Li, Yongchun; Zhang, Ling; Ye, Yang; Yang, Qingquan; Zhang, Tao; Cheng, Yingjie; Xu, Jichan; Wang, Liang; Xu, Liqing; Zhao, Hailin; Wang, Fudi; Lin, Shiyao; Wu, Bin; Lyu, Bo; Xu, Guosheng; Gao, Xiang; Shi, Tonghui; He, Kaiyang; Lan, Heng; Chu, Nan; Cao, Bin; Sun, Zhen; Zuo, Guizhong; Ren, Jun; Zhuang, Huidong; Li, Changzheng; Yuan, Xiaolin; Yu, Yaowei; Wang, Houyin; Chen, Yue; Wu, Jinhua; EAST Team

    2016-05-01

    Increasing the density in a tokamak is limited by the so-called density limit, which is generally performed as an appearance of disruption causing loss of plasma confinement, or a degradation of high confinement mode which could further lead to a H  →  L transition. The L-mode and H-mode density limit has been investigated in EAST tokamak. Experimental results suggest that density limits could be triggered by either edge cooling or excessive central radiation. The L-mode density limit disruption is generally triggered by edge cooling, which leads to the current profile shrinkage and then destabilizes a 2/1 tearing mode, ultimately resulting in a disruption. The L-mode density limit scaling agrees well with the Greenwald limit in EAST. The observed H-mode density limit in EAST is an operational-space limit with a value of 0.8∼ 0.9{{n}\\text{GW}} . High density H-mode heated by neutral beam injection (NBI) and lower hybrid current drive (LHCD) are analyzed, respectively. The constancy of the edge density gradients in H-mode indicates a critical limit caused perhaps by e.g. ballooning induced transport. The maximum density is accessed at the H  →  L transition which is generally caused by the excessive core radiation due to high Z impurities (Fe, Cu). Operating at a high density (>2.8× {{10}19} {{\\text{m}}-3} ) is favorable for suppressing the beam shine through NBI. High density H-mode up to 5.3× {{10}19}{{\\text{m}}-3}~≤ft(∼ 0.8{{n}\\text{GW}}\\right) could be sustained by 2 MW 4.6 GHz LHCD alone, and its current drive efficiency is studied. Statistics show that good control of impurities and recycling facilitate high density operation. With careful control of these factors, high density up to 0.93{{n}\\text{GW}} stable H-mode operation was carried out heated by 1.7 MW LHCD and 1.9 MW ion cyclotron resonance heating with supersonic molecular beam injection fueling.

  17. High-Resolution, Wide-Field-of-View Scanning Telescope

    NASA Technical Reports Server (NTRS)

    Sepulveda, Cesar; Wilson, Robert; Seshadri, Suresh

    2007-01-01

    A proposed telescope would afford high resolution over a narrow field of view (<0.10 ) while scanning over a total field of view nominally 16 wide without need to slew the entire massive telescope structure. The telescope design enables resolution of a 1-m-wide object in a 50- km-wide area of the surface of the Earth as part of a 200-km-wide area field of view monitored from an orbit at an altitude of 700 km. The conceptual design of this telescope could also be adapted to other applications both terrestrial and extraterrestrial in which there are requirements for telescopes that afford both wide- and narrow-field capabilities. In the proposed telescope, the scanning would be effected according to a principle similar to that of the Arecibo radio telescope, in which the primary mirror is stationary with respect to the ground and a receiver is moved across the focal surface of the primary mirror. The proposed telescope would comprise (1) a large spherical primary mirror that would afford high resolution over a narrow field of view and (2) a small displaceable optical relay segment that would be pivoted about the center of an aperture stop to effect the required scanning (see figure). Taken together, both comprise a scanning narrow-angle telescope that does not require slewing the telescope structure. In normal operation, the massive telescope structure would stare at a fixed location on the ground. The inner moveable relay optic would be pivoted to scan the narrower field of view over the wider one, making it possible to retain a fixed telescope orientation, while obtaining high-resolution images over multiple target areas during an interval of 3 to 4 minutes in the intended orbit. The pivoting relay segment of the narrow-angle telescope would include refractive and reflective optical elements, including two aspherical mirrors, to counteract the spherical aberration of the primary mirror. Overall, the combination of the primary mirror and the smaller relay optic

  18. Investigation of the jet-wake flow of a highly loaded centrifugal compressor impeller

    NASA Technical Reports Server (NTRS)

    Eckardt, D.

    1978-01-01

    Investigations, aimed at developing a better understanding of the complex flow field in high performance centrifugal compressors were performed. Newly developed measuring techniques for unsteady static and total pressures as well as flow directions, and a digital data analysis system for fluctuating signals were thoroughly tested. The loss-affected mixing process of the distorted impeller discharge flow was investigated in detail, in the absolute and relative system, at impeller tip speeds up to 380 m/s. A theoretical analysis proved good coincidence of the test results with the DEAN-SENOO theory, which was extended to compressible flows.

  19. Investigation of Rare Particle Production in High Energy Nuclear Collisions

    SciTech Connect

    1999-09-02

    Our program is an investigation of the hadronization process through measurement of rare particle production in high energy nuclear interactions. Such collisions of heavy nuclei provide an environment similar in energy density to the conditions in the Big Bang. We are currently involved in two major experiments to study this environment, E896 at the AGS and STAR at RHIC. We have completed our physics running of E896, a search for the H dibaryon and measurement of hyperon production in AuAu collisions, and are in the process of analyzing the data. We have produced the electronics and software for the STAR trigger and will begin to use these tools to search for anti-nuclei and strange hadrons when RHIC turns on later this year.

  20. Rheological investigation of highly filled polymers: Effect of molecular weight

    NASA Astrophysics Data System (ADS)

    Hnatkova, Eva; Hausnerova, Berenika; Hales, Andrew; Jiranek, Lukas; Vera, Juan Miguel Alcon

    2015-04-01

    The paper deals with rheological properties of highly filled polymers used in powder injection molding. Within the experimental framework seven PIM feedstocks based on superalloy Inconel 718 powder were prepared. Each feedstock contains the fixed amount of powder loading and the same composition of binder system consisting of three components: polyethylene glycol (PEG) differing in molecular weight, poly (methyl methacrylate) (PMMA) and stearic acid (SA). The aim is to investigate the influence of PEG's molecular weight on the flow properties of feedstocks. Non-Newtonian indices, representing the shear rate sensitivity of the feedstocks, are obtained from a polynomial fit, and found to vary within measured shear rates range from 0.2 to 0.8. Temperature effect is considered via activation energies, showing decreasing trend with increasing of molecular weight of PEG (except of feedstock containing 1,500 g.mol-1 PEG).

  1. Investigation of high voltage spacecraft system interactions with plasma environments

    NASA Technical Reports Server (NTRS)

    Stevens, N. J.; Berkopec, F. D.; Purvis, C. K.; Grier, N.; Staskus, J.

    1978-01-01

    The exposure of high voltage spacecraft systems to the charged particle environment of space can produce interactions that will influence system operation. An experimental investigation of these interactions has been undertaken for insulator and conductor test surfaces biased up to plus or minus 1 kV in a simulated low earth orbit charged particle environment. It has been found that these interactions are controlled by the insulator surfaces surrounding the biased conductors. For positive applied voltages the electron current collection can be enhanced by the insulators. For negative applied voltages the insulator surface confines the voltage to the conductor region; this can cause arcing. Understanding these interactions and the technology to control their impact on system operation is essential to the design of solar cell arrays for ion drive propulsion applications that use direct drive power processing.

  2. An investigation of thermal comfort at high humidities

    SciTech Connect

    Fountain, M.E.; Arens, E. Xu, T.; Bauman, F.S.; Oguru, Masayuki

    1999-07-01

    Climate chamber experiments were performed to investigate thermal comfort at high humidities. Subjective reports were recorded for a total of 411 subjects at frequent intervals during the three-hour experiments with 65 selected subjects equipped with instrumentation to record skin wettedness and skin temperature. The exposures ranged from 20 C/60% RH to 26 C/90% RH with two clothing levels, 0.5 and 0.9 clo, and three levels of metabolic activity, 1.2, 1.6, and 4 met. Clear differences in humidity response were not found for sedentary subjects; however, non-sedentary activities produced differences on several subjective scales. These differences, though, are dictated via heat balance and thermoregulation and cannot be separated from humidity-related effects. For metabolic rates 1.6 met and above, these data suggest that no practical limit on humidity will lower the percent dissatisfied below 25%.

  3. An experimental investigation of helicopter rotor high frequency broadband noise

    NASA Technical Reports Server (NTRS)

    Lee, A.; Aravamudan, K. S.; Bauer, P.; Harris, W. L.

    1977-01-01

    The paper describes experiments involving a 4.17 foot diameter model rotor operating in a 5 times 7.5 ft open jet wind tunnel enclosed in an anechoic chamber. The effects of rotor thrust, advance ratio, and the number of blades on the intensity and spectrum of high frequency broadband noise (HFBN) have been investigated. The effects of each parameter were determined by keeping the other two constant. The directivities of the two- and three-bladed rotors were measured in a direction perpendicular to the plane of the rotor disk. The effects of heading edge, pressure side, and suction side serrations on HFBN were measured under several operating conditions, and the effects of the serrations on the mean thrust generated by the rotor were studied. A scaling law is proposed to determine the location of the peak frequency and intensity of HFBN.

  4. Colloid-Facilitated Transport of Low-Solubility Radionuclides: A Field, Experimental, and Modeling Investigation

    SciTech Connect

    Kersting, A B; Reimus, P W; Abdel-Fattah, A; Allen, P G; Anghel, I; Benedict, F C; Esser, B K; Lu, N; Kung, K S; Nelson, J; Neu, M P; Reilly, S D; Smith, D K; Sylwester, E R; Wang, L; Ware, S D; Warren, RG; Williams, R W; Zavarin, M; Zhao, P

    2003-02-01

    rate of Pu transport. Currently, the role of colloids in facilitating the transport of low-solubility radionuclides is not understood well enough to effectively model contaminant transport. A fundamental understanding of the role that colloids may or may not play in the transport of low-solubility radionuclides is needed in order to predict contaminant transport, design remediation strategies and provide risk assessments. Ryan and Elimelech (1996) have argued that in order to evaluate the potential for colloids to transport radionuclides, several criteria must be met: (1) colloids must exist and be stable, (2) radionuclides must have a high sorption affinity for the colloids, and (3) colloids must be transported. Only then can we understand the conditions where colloids can and will facilitate transport of radionuclides. In this report we compile the results from a series of field, laboratory and modeling studies funded by the UGTA program in order to evaluate the potential for colloids to transport low-solubility radionuclides at the NTS. The studies presented in this report fall under three general areas of investigation: Characterization of natural colloids in groundwater at NTS, Pu sorption/desorption experiments on colloid minerals identified in NTS groundwater, and Transport of Pu-doped colloids through fractured rock core. Chapter 1 is a background review of our current understanding of colloids and their role in facilitating contaminant transport. Chapters 2, and 3 are field studies that focused on characterizing natural colloids at different hydrologic environments at the NTS and address Ryan and Elimelech's (1996) first criteria regarding the existence and stability of colloids. Chapters 4, 5 and 6 are laboratory experimental studies that investigate the sorption/desorption behavior of Pu and other low-solubility radionuclides on colloid minerals observed in NTS groundwater. These studies evaluate Ryan and Elimelech's (1996) second criteria that the affinity

  5. The High Field Phase Diagram of (2) Perchlorate Tetramethyltetraselenafulvalene

    NASA Astrophysics Data System (ADS)

    McKernan, Steffen Keleher

    1995-11-01

    We have established the magnetic phase diagram of (TMTSF)_2ClO_4 to fields of 30 tesla at temperatures above 0.5 K. The phase diagram is derived from a wealth of data amassed on six physical parameters, rho_ {xx}, rho_{yy }, rho_{zz} , rho_{xy}, S_{xx} (thermopower) and magnetization. The cascade of field induced spin density waves produced by fields along the crystalline c-axis and known to exist below 8 T, saturates to a maximum transition temperature of 5.5 K at approximately 15 T. This second order phase boundary persists at 5.5 K to 30 T. Wholly contained within this upper phase boundary, there is a newly discovered first order phase line which begins in an apparent critical point at 3.5 K and 22 T. This lower phase boundary continues at constant temperature to ~26 T, where it begins to decrease in temperature, falling below our measurement range at approximately 27 T. The previously reported high field reentrance to the normal state, is not found. (TMTSF)_2ClO_4 is formed by stacking the planar tetramethyltetraselenafulvalene (TMTSF) molecules along the crystalline a-axis. These stacks are separated along the c-axis by the perchlorate anions. At 24 K, the pyramidal anions order with wave vector (0, 1over 2, 0), thus distinguishing alternate chains and giving rise to two distinct Fermi surfaces. The high field spin density wave states are tentatively interpreted in terms of separate, weakly coupled transitions on these Fermi surfaces.

  6. Ultra-high field magnets for whole-body MRI

    NASA Astrophysics Data System (ADS)

    Warner, Rory

    2016-09-01

    For whole-body MRI, an ultra-high field (UHF) magnet is currently defined as a system operating at 7 T or above. Over 70 UHF magnets have been built, all with the same technical approach originally developed by Magnex Scientific Ltd. The preferred coil configuration is a compensated solenoid. In this case, the majority of the field is generated by a simple long solenoid that stretches the entire length of the magnet. Additional coils are wound on a separate former outside the main windings with the purpose of balancing the homogeneity. Most of the magnets currently in operation are passively shielded systems where the magnet is surrounded by a steel box of 200–870 tonnes of carbon steel. More recently actively shielded magnets have been built for operation at 7 T; in this case the stray field is controlled by with reverse turns wound on a separate former outside the primary coils. Protection against quench damage is much more complex with an actively shielded magnet design due to the requirement to prevent the stray field from increasing during a quench. In the case of the 7 T 900 magnet this controlled by combining some of the screening coils into each section of the protection circuit. Correction of the field variations caused by manufacturing tolerances and environmental effects are made with a combination of superconducting shims and passive shims. Modern UHF magnets operate in zero boil-off mode with the use of cryocoolers with cooling capacity at 4.2 K. Although there are no cryogen costs associated with normal operation UHF magnets require a significant volume (10 000–20 000 l) of liquid helium for the cool-down. Liquid helium is expensive therefore new methods of cool-down using high-power cryocoolers are being implemented to reduce the requirement.

  7. The magnetic field investigation on the Ulysses mission - Instrumentation and preliminary scientific results

    NASA Technical Reports Server (NTRS)

    Balogh, A.; Beek, T. J.; Forsyth, R. J.; Hedgecock, P. C.; Marquedant, R. J.; Smith, E. J.; Southwood, D. J.; Tsurutani, B. T.

    1992-01-01

    A fundamental feature of the heliosphere is the three-dimensional structure of the interplanetary magnetic field. The magnetic field investigation on Ulysses, the first space probe to explore the out-of-ecliptic and polar heliosphere, aims at determining the large-scale features and gradients of the field, as well as the heliolatitude dependence of interplanetary phenomena so far only observed near the ecliptic plane. The Ulysses magnetometer uses two sensors, one a Vector Helium Magnetometer, the other a Fluxgate Magnetometer. Onboard data processing yields measurements of the magnetic field vector with a time resolution up to 2 vectors/second and a sensitivity of about 10 pT. Since the switch-on of the instrument in flight on 25 October 1990, a steady stream of observations has been made, indicating that at this phase of the solar cycle the field is generally disturbed: several shock waves and a large number of discontinuities have been observed, as well as several periods with apparently intense wave activity. The paper gives a brief summary of the scientific objectives of the investigation, followed by a detailed description of the instrument and its characteristics. Examples of wave bursts, interplanetary shocks and crossings of the heliospheric current sheet are given to illustrate the observations made with the instrument.

  8. Low-temperature scanning system for near- and far-field optical investigations.

    PubMed

    Kazantsev, D V; Dal Savio, C; Pierz, K; Güttler, B; Danzebrink, H-U

    2003-03-01

    A combined system for far- and near-field optical spectroscopy consisting of a compact scanning near-field optical microscope and a dedicated spectrometer was realized. The set-up allows the optical investigation of samples at temperatures from 10 to 300 K. The sample positioning range is as large as 5 x 5 x 5 mm3 and the spatial resolution is in the range of 1.5 micro m in the far-field optical microscopy mode at low temperatures. In the scanning near-field optical microscope mode the resolution is defined by the microfabricated cantilever probe, which is placed in the focus of a double-mirror objective. The tip-to-sample distance in the scanning near-field optical microscope is controlled by a beam deflection system in dynamic scanning force microscopy mode. After a description of the apparatus, scanning force topography images of self-assembled InAs quantum dots on a GaAs substrate with a density of less than one dot per square micrometre are shown, followed by the first spectroscopic investigations of such a sample. The presented results demonstrate the potential of the system. PMID:12641762

  9. A method to localize RF B₁ field in high-field magnetic resonance imaging systems.

    PubMed

    Yoo, Hyoungsuk; Gopinath, Anand; Vaughan, J Thomas

    2012-12-01

    In high-field magnetic resonance imaging (MRI) systems, B₀ fields of 7 and 9.4 T, the RF field shows greater inhomogeneity compared to clinical MRI systems with B₀ fields of 1.5 and 3.0 T. In multichannel RF coils, the magnitude and phase of the input to each coil element can be controlled independently to reduce the nonuniformity of the RF field. The convex optimization technique has been used to obtain the optimum excitation parameters with iterative solutions for homogeneity in a selected region of interest. The pseudoinverse method has also been used to find a solution. The simulation results for 9.4- and 7-T MRI systems are discussed in detail for the head model. Variation of the simulation results in a 9.4-T system with the number of RF coil elements for different positions of the regions of interest in a spherical phantom are also discussed. Experimental results were obtained in a phantom in the 9.4-T system and are compared to the simulation results and the specific absorption rate has been evaluated. PMID:22929360

  10. High Energy Solar Spectroscopic Imager (HESSI) Team Investigations

    NASA Technical Reports Server (NTRS)

    Emslie, A. Gordon

    1998-01-01

    This report covers activities on the above grant for the period through the end of September 1997. The work originally proposed to be performed under a three-year award was converted at that time to a two-year award for the remainder of the period, and is now funded under award NAGS-4027 through Goddard Space Flight Center. The P.I. is a co-investigator on the High Energy Solar Spectroscopic Imager (HESSI) team, selected as a Small-Class Explorer (SNMX) mission in 1997. He has also been a participant in the Space Physics Roadmap Planning Group. Our research has been strongly influenced by the NASA mission opportunities related to these activities. The report is subdivided into four sections, each dealing with a different aspect of our research within this guiding theme. Personnel involved in this research at UAH include the P.I. and graduate students Michele Montgomery and Amy Winebarger. Much of the work has been carried out in collaboration with investigators at other institutions, as detailed below. Attachment: Laser wakefield acceleration and astrophysical applications.

  11. High Energy Solar Spectroscopic Imager (HESSI) Team Investigations

    NASA Astrophysics Data System (ADS)

    Emslie, A. Gordon

    1998-04-01

    This report covers activities on the above grant for the period through the end of September 1997. The work originally proposed to be performed under a three-year award was converted at that time to a two-year award for the remainder of the period, and is now funded under award NAGS-4027 through Goddard Space Flight Center. The P.I. is a co-investigator on the High Energy Solar Spectroscopic Imager (HESSI) team, selected as a Small-Class Explorer (SNMX) mission in 1997. He has also been a participant in the Space Physics Roadmap Planning Group. Our research has been strongly influenced by the NASA mission opportunities related to these activities. The report is subdivided into four sections, each dealing with a different aspect of our research within this guiding theme. Personnel involved in this research at UAH include the P.I. and graduate students Michele Montgomery and Amy Winebarger. Much of the work has been carried out in collaboration with investigators at other institutions, as detailed below. Attachment: Laser wakefield acceleration and astrophysical applications.

  12. Design and optimization of force-reduced high field magnets

    NASA Astrophysics Data System (ADS)

    Rembeczki, Szabolcs

    High field magnets have many important applications in different areas of research, in the power industry and also for military purposes. For example, high field magnets are particularly useful in: material sciences, high energy physics, plasma physics (as fusion magnets), high power applications (as energy storage devices), and space applications (in propulsion systems). One of the main issues with high-field magnets is the presence of very large electromagnetic stresses that must be counteracted and therefore require heavy support structures. In superconducting magnets, the problems caused by Lorentz forces are further complicated by the fact that superconductors for high field applications are pressure sensitive. The current carrying capacity is greatly reduced under stress and strain (especially in the case of Nb 3Sn and the new high temperature superconductors) so the reduction of the acting forces is of even greater importance. Different force-reduced magnet concepts have been studied in the past, both numerical and analytical methods have been used to solve this problem. The developed concepts are based on such complex winding geometries that the realization and manufacturing of such coils is extremely difficult and these concepts are mainly of theoretical interest. In the presented research, a novel concept for force-reduced magnets has been developed and analyzed which is easy to realize and therefore is of practical interest. The analysis has been performed with a new methodology, which does not require the time consuming finite element calculations. The developed computer models describe the 3-dimensional winding configuration by sets of filaments (filamentary approximation). This approach is much faster than finite element analysis and therefore allows rapid optimization of concepts. The method has been extensively tested on geometries of force-reduced solenoids where even analytical solutions exist. As a further cross check, the developed computer

  13. Cryogenic properties of dispersion strengthened copper for high magnetic fields

    SciTech Connect

    Toplosky, V. J.; Han, K.; Walsh, R. P.; Swenson, C. A.

    2014-01-27

    Cold deformed copper matrix composite conductors, developed for use in the 100 tesla multi-shot pulsed magnet at the National High Magnetic Field Laboratory (NHMFL), have been characterized. The conductors are alumina strengthened copper which is fabricated by cold drawing that introduces high dislocation densities and high internal stresses. Both alumina particles and high density of dislocations provide us with high tensile strength and fatigue endurance. The conductors also have high electrical conductivities because alumina has limited solubility in Cu and dislocations have little scattering effect on conduction electrons. Such a combination of high strength and high conductivity makes it an excellent candidate over other resistive magnet materials. Thus, characterization is carried out by tensile testing and fully reversible fatigue testing. In tensile tests, the material exceeds the design criteria parameters. In the fatigue tests, both the load and displacement were measured and used to control the amplitude of the tests to simulate the various loading conditions in the pulsed magnet which is operated at 77 K in a non-destructive mode. In order to properly simulate the pulsed magnet operation, strain-controlled tests were more suitable than load controlled tests. For the dispersion strengthened coppers, the strengthening mechanism of the aluminum oxide provided better tensile and fatigue properties over convention copper.

  14. Internal Electric Field Behavior of Cadmium Zinc Telluride Radiation Detectors Under High Carrier Injection

    SciTech Connect

    Yang, G.; Bolotnikov, A.E.; Camarda, G.S.; Cui, Y.; Hossain, A.; Kim, K.H.; Gul, R.; and James, R.B.

    2010-10-26

    The behavior of the internal electric-field of nuclear-radiation detectors substantially affects the detector's performance. We investigated the distribution of the internal field in cadmium zinc telluride (CZT) detectors under high carrier injection. We noted the build-up of a space charge region near the cathode that produces a built-in field opposing the applied field. Its presence entails the collapse of the electric field in the rest of detector, other than the portion near the cathode. Such a space-charge region originates from serious hole-trapping in CZT. The device's operating temperature greatly affects the width of the space-charge region. With increasing temperature from 5 C to 35 C, its width expanded from about 1/6 to 1/2 of the total depth of the detector.

  15. Compliance with High-Intensity Radiated Fields Regulations - Emitter's Perspective

    NASA Technical Reports Server (NTRS)

    Statman, Joseph; Jamnejad, Vahraz; Nguyen, Lee

    2012-01-01

    NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.The DSN is in the process of revamping its documentation to provide analysis of the High Intensity Radiation Fields (HIRF) environment resulting from radio frequency radiation from DSN antennas for comparison to FAA regulations regarding certification of HIRF protection as outlined in the FAA regulations on HIRF protection for aircraft electrical and electronic systems (Title 14, Code of Federal Regulations (14 CFR) [section sign][section sign] 23.1308, 25.1317, 27.1317, and 29.1317).This paper presents work done at JPL, in consultation with the FAA. The work includes analysis of the radiated field structure created by the unique DSN emitters (combination of transmitters and antennas) and comparing it to the fields defined in the environments in the FAA regulations. The paper identifies areas that required special attention, including the implications of the very narrow beam of the DSN emitters and the sidereal rate motion. The paper derives the maximum emitter power allowed without mitigation and the mitigation zones, where required.Finally, the paper presents summary of the results of the analyses of the DSN emitters and the resulting DSN process documentation.

  16. High-resolution heteronuclear multi-dimensional NMR spectroscopy in magnetic fields with unknown spatial variations

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiyong; Huang, Yuqing; Smith, Pieter E. S.; Wang, Kaiyu; Cai, Shuhui; Chen, Zhong

    2014-05-01

    Heteronuclear NMR spectroscopy is an extremely powerful tool for determining the structures of organic molecules and is of particular significance in the structural analysis of proteins. In order to leverage the method’s potential for structural investigations, obtaining high-resolution NMR spectra is essential and this is generally accomplished by using very homogeneous magnetic fields. However, there are several situations where magnetic field distortions and thus line broadening is unavoidable, for example, the samples under investigation may be inherently heterogeneous, and the magnet’s homogeneity may be poor. This line broadening can hinder resonance assignment or even render it impossible. We put forth a new class of pulse sequences for obtaining high-resolution heteronuclear spectra in magnetic fields with unknown spatial variations based on distant dipolar field modulations. This strategy’s capabilities are demonstrated with the acquisition of high-resolution 2D gHSQC and gHMBC spectra. These sequences’ performances are evaluated on the basis of their sensitivities and acquisition efficiencies. Moreover, we show that by encoding and decoding NMR observables spatially, as is done in ultrafast NMR, an extra dimension containing J-coupling information can be obtained without increasing the time necessary to acquire a heteronuclear correlation spectrum. Since the new sequences relax magnetic field homogeneity constraints imposed upon high-resolution NMR, they may be applied in portable NMR sensors and studies of heterogeneous chemical and biological materials.

  17. Dynamic behavior of magnetoelectric coupling of CuFeO2 induced by a high magnetic field

    NASA Astrophysics Data System (ADS)

    Xia, Nianming; Shi, Liran; Xia, Zhengcai; Chen, Borong; Jin, Zhao; Wang, Yeshuai; Ouyang, Zhongwen; Zuo, Huakun; Shen, Yining

    2014-03-01

    Magnetoelectric effects and their dynamic behavior in a CuFeO2 single crystal grown by the floating zone technique are investigated at low temperature in pulsed high magnetic fields. Experimental results show that the magnetization, dielectric polarization, and magnetoelectric coupling are anisotropic. In the magnetization, a field-induced multi-step-like transition with hysteresis is observed, in which the critical magnetic fields are independent of the field sweep rate. In the dielectric polarization, the field-induced dielectric polarization with hysteresis (or partial irreversible) is only observed in the incommensurate-noncollinear phase. In particular, no obvious spontaneous dielectric polarization is observed in the lower magnetic field regime. Using a pulsed high magnetic field with various magnetic field strength and field sweep rates, the coupling behavior between the magnetic moment and the dielectric polarization is investigated. Experimental results show that the dielectric polarization is weakly related to the field sweep rate. In the field-decreasing branch, the magnetic field is higher, the magnetic field region of the dielectric polarization remains is lower, indicating that the pulsed high magnetic field has an effect on the enhancement of the spontaneous dielectric polarization.

  18. Mars' "Magnetospheric" Response to Interplanetary Field Orientation: Inferences from Models for MAVEN Investigation

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Dong, C.; Ma, Y.-J.; Curry, S. M.; Alvarez, K.; Hara, T.; Halekas, J.; Brain, D. A.; Bougher, S.; Espley, J.

    2015-10-01

    Planetary space weather at Mars has attracted much interest, but the focus is usually on the response to solar activity and its related disturbances in the solar wind. While this aspect is important and may be key to understanding Mars' atmosphere evolution, an additional consideration is based on the sensitivity of Earth's magnetospheric solar wind interaction to southward interplanetary magnetic fields. The study described here investigates whether Mars has its own specific interplanetary field orientation sensitivities that might be identified in the MAVEN data analyses.

  19. The erosion of carbonate stone by acid rain: Laboratory and field investigations

    SciTech Connect

    Baedecker, P.A. ); Reddy, M.M. )

    1993-02-01

    This paper describes a laboratory experiment on the effects of acidic deposition on carbonate stone erosion. It can serve as the basis for an undergraduate (or pre college) experiment in environmental chemistry. Recent field investigations are described that provide measurements of carbonate stone dissolution and mechanical erosion under weathering conditions that are prevalent in the eastern US. The purpose of the laboratory work is to answer questions concerning the effects of hydrogen ion deposition on stone erosion processes that were difficult to resolve on the basis of field experiments alone.

  20. 2002 Initial Assessments for B-BX-BY Field Investigation Report (FIR): Numerical Simulations

    SciTech Connect

    Freedman, Vicky L.; Williams, Mark D.; Cole, C. R.; White, Mark D.; Bergeron, Marcel P.

    2002-08-25

    IIn support of CH2M HILL Hanford Group, Inc.'s (CHG) preparation of a Field Investigative Report (FIR) for the Hanford Site Single-Shell Tank (SST) Waste Management Area (WMA) B-BX-BY, a set of numerical simulations of flow and solute transport was executed to predict the performance of surface barriers for reducing long-term risks from potential groundwater contamination at the B-BX-BY WMA. This report documents the simulation of 14 cases involving two-dimensional cross sections through the B-BX-BY WMA. Two cross-sections were used for this analysis, one through the BX WMA from tanks BX-108 to BX-102, and another through the trench B-38 for simulating B trench discharges. The simulations were used to investigate the impact of surface barriers, water-line leaks, inventory placement, meteoric recharge and partitioning between the aqueous and sorbed phases. Three transported solutes were considered: uranium-238 (U-238), technetium-99 (Tc-99), and nitrate (NO3). For the BX tank simulations, results showed that simulations investigating water-line leaks demonstrated the highest peak concentrations. Interim barriers had a significant impact on peak concentrations in later times, but not in early times due to a high concentration zone of contaminants near the water table. Overall, simulation results for the BX WMA showed that only a small fraction of the U-238 inventory migrated from the vadose zone in most of the test cases. In general, similar peak WMA concentrations occurred for all of the simulations (<800 pCi/L for Tc-99 and <800 mg/L for NO3), with the exception of the water-line leak cases. In the B trench cases, simulations predicted that the U-238 would not migrate from the vadose zone to the aquifer in the thousand years that were simulated. The simulations also predicted that Tc-99 would appear quickly in the aquifer following the trench discharge in 1954, with peak concentrations occurring around 2020 to 2030.