Science.gov

Sample records for field evaluation due

  1. Comments on "Evaluation of interactions of electric fields due to electrostatic discharge with human tissue".

    PubMed

    Seaman, Ronald L; Comeaux, James A

    2006-06-01

    Attention is drawn to recent paper by Rogers et al. (Aug., 2004) in which ultra-wideband pulses are applied to an isolated muscle as part of deriving a strength-duration curve for threshold stimulation. The paper extends the strength-duration threshold curve for unipolar pulses down to a pulse duration of about 1 ns, on the order of 1000 times shorter than previously studied. Results of the work justify use of traditional mathematical models of the strength-duration curve for nanosecond pulses, as done recently for the electric field resulting from electrostatic discharge through the body (Dawson, et al., 2004). PMID:16761853

  2. Development of an algorithm for evaluating personal doses due to photon fields in terms of operational quantities for TLD badge system in India.

    PubMed

    Pradhan, S M; Sneha, C; Chourasiya, G; Adtani, M M; Tripathi, S M; Singh, S K

    2009-09-01

    In order to evaluate and report the personal doses in terms of personal dose equivalent, the performance of the CaSO(4):Dy based thermoluminescence dosemeter (TLD) badge used for countrywide personnel monitoring in India is investigated using monoenergetic and narrow spectrum radiation qualities equivalent to those given in ISO standards. Algorithms suitable for evaluating H(p)(10) and H(p)(0.07) within +/- 30 % are developed from the responses of dosemeter elements/discs under different filters for normal as well as angular irradiation conditions using these beams. The algorithm is tested for TLD badges irradiated to mixtures of low- and high-energy ((137)Cs) beams in various proportions. The paper concludes with the results of test of algorithm by evaluation of badges used in the IAEA/RCA intercomparison studies and discussion on inherent limitations. PMID:19755432

  3. Anisotropy in MHD turbulence due to a mean magnetic field

    NASA Technical Reports Server (NTRS)

    Shebalin, J. V.; Matthaeus, W. H.; Montgomery, D.

    1982-01-01

    The development of anisotropy in an initially isotropic spectrum is studied numerically for two-dimensional magnetohydrodynamic turbulence. The anisotropy develops due to the combined effects of an externally imposed dc magnetic field and viscous and resistive dissipation at high wave numbers. The effect is most pronounced at high mechanical and magnetic Reynolds numbers. The anisotropy is greater at the higher wave numbers.

  4. Flow damping due to stochastization of the magnetic field

    PubMed Central

    Ida, K.; Yoshinuma, M.; Tsuchiya, H.; Kobayashi, T.; Suzuki, C.; Yokoyama, M.; Shimizu, A.; Nagaoka, K.; Inagaki, S.; Itoh, K.; Akiyama, T.; Emoto, M.; Evans, T.; Dinklage, A.; Du, X.; Fujii, K.; Goto, M.; Goto, T.; Hasuo, M.; Hidalgo, C.; Ichiguchi, K.; Ishizawa, A.; Jakubowski, M.; Kamiya, K.; Kasahara, H.; Kawamura, G.; Kato, D.; Kobayashi, M.; Morita, S.; Mukai, K.; Murakami, I.; Murakami, S.; Narushima, Y.; Nunami, M.; Ohdach, S.; Ohno, N.; Osakabe, M.; Pablant, N.; Sakakibara, S.; Seki, T.; Shimozuma, T.; Shoji, M.; Sudo, S.; Tanaka, K.; Tokuzawa, T.; Todo, Y.; Wang, H.; Yamada, H.; Takeiri, Y.; Mutoh, T.; Imagawa, S.; Mito, T.; Nagayama, Y.; Watanabe, K. Y.; Ashikawa, N.; Chikaraishi, H.; Ejiri, A.; Furukawa, M.; Fujita, T.; Hamaguchi, S.; Igami, H.; Isobe, M.; Masuzaki, S.; Morisaki, T.; Motojima, G.; Nagasaki, K.; Nakano, H.; Oya, Y.; Suzuki, Y.; Sakamoto, R.; Sakamoto, M.; Sanpei, A.; Takahashi, H.; Tokitani, M.; Ueda, Y.; Yoshimura, Y.; Yamamoto, S.; Nishimura, K.; Sugama, H.; Yamamoto, T.; Idei, H.; Isayama, A.; Kitajima, S.; Masamune, S.; Shinohara, K.; Bawankar, P. S.; Bernard, E.; von Berkel, M.; Funaba, H.; Huang, X. L.; Ii, T.; Ido, T.; Ikeda, K.; Kamio, S.; Kumazawa, R.; Moon, C.; Muto, S.; Miyazawa, J.; Ming, T.; Nakamura, Y.; Nishimura, S.; Ogawa, K.; Ozaki, T.; Oishi, T.; Ohno, M.; Pandya, S.; Seki, R.; Sano, R.; Saito, K.; Sakaue, H.; Takemura, Y.; Tsumori, K.; Tamura, N.; Tanaka, H.; Toi, K.; Wieland, B.; Yamada, I.; Yasuhara, R.; Zhang, H.; Kaneko, O.; Komori, A.

    2015-01-01

    The driving and damping mechanism of plasma flow is an important issue because flow shear has a significant impact on turbulence in a plasma, which determines the transport in the magnetized plasma. Here we report clear evidence of the flow damping due to stochastization of the magnetic field. Abrupt damping of the toroidal flow associated with a transition from a nested magnetic flux surface to a stochastic magnetic field is observed when the magnetic shear at the rational surface decreases to 0.5 in the large helical device. This flow damping and resulting profile flattening are much stronger than expected from the Rechester–Rosenbluth model. The toroidal flow shear shows a linear decay, while the ion temperature gradient shows an exponential decay. This observation suggests that the flow damping is due to the change in the non-diffusive term of momentum transport. PMID:25569268

  5. Alignment of atmospheric mineral dust due to electric field

    NASA Astrophysics Data System (ADS)

    Ulanowski, Z.; Bailey, J.; Lucas, P. W.; Hough, J. H.; Hirst, E.

    2007-12-01

    Optical polarimetry observations on La Palma, Canary Islands, during a Saharan dust episode show dichroic extinction indicating the presence of vertically aligned particles in the atmosphere. Modelling of the extinction together with particle orientation indicates that the alignment could have been due to an electric field of the order of 2 kV/m. Two alternative mechanisms for the origin of the field are examined: the effect of reduced atmospheric conductivity and charging of the dust layer, the latter effect being a more likely candidate. It is concluded that partial alignment may be a common feature of Saharan dust layers. The modelling indicates that the alignment can significantly alter dust optical depth. This "Venetian blind effect" may have decreased optical thickness in the vertical direction by as much as 10% for the case reported here. It is also possible that the alignment and the electric field modify dust transport.

  6. Biological effects due to weak magnetic field on plants

    NASA Astrophysics Data System (ADS)

    Belyavskaya, N. A.

    2004-01-01

    Throughout the evolution process, Earth's magnetic field (MF, about 50 μT) was a natural component of the environment for living organisms. Biological objects, flying on planned long-term interplanetary missions, would experience much weaker magnetic fields, since galactic MF is known to be 0.1-1 nT. However, the role of weak magnetic fields and their influence on functioning of biological organisms are still insufficiently understood, and is actively studied. Numerous experiments with seedlings of different plant species placed in weak magnetic field have shown that the growth of their primary roots is inhibited during early germination stages in comparison with control. The proliferative activity and cell reproduction in meristem of plant roots are reduced in weak magnetic field. Cell reproductive cycle slows down due to the expansion of G 1 phase in many plant species (and of G 2 phase in flax and lentil roots), while other phases of cell cycle remain relatively stabile. In plant cells exposed to weak magnetic field, the functional activity of genome at early pre-replicate period is shown to decrease. Weak magnetic field causes intensification of protein synthesis and disintegration in plant roots. At ultrastructural level, changes in distribution of condensed chromatin and nucleolus compactization in nuclei, noticeable accumulation of lipid bodies, development of a lytic compartment (vacuoles, cytosegresomes and paramural bodies), and reduction of phytoferritin in plastids in meristem cells were observed in pea roots exposed to weak magnetic field. Mitochondria were found to be very sensitive to weak magnetic field: their size and relative volume in cells increase, matrix becomes electron-transparent, and cristae reduce. Cytochemical studies indicate that cells of plant roots exposed to weak magnetic field show Ca 2+ over-saturation in all organelles and in cytoplasm unlike the control ones. The data presented suggest that prolonged exposures of plants to weak

  7. Lower Atmospheric Electric Field due to Cloud Charge Distribution

    NASA Astrophysics Data System (ADS)

    Paul, Suman; Haldar, Dilip kumar; Sundar De, Syam; Ghosh, Abhijit; Hazra, Pranab; Bandyopadhyay, Bijoy

    2016-07-01

    The distributions of electric charge in the electrified clouds introduce important effects in the ionosphere and into the region between the ionosphere and the Earth. The electrical properties of the medium are changed greatly between thundercloud altitudes and the magnetosphere. A model for the penetration of DC thundercloud electric field between the Earth's upper and lower atmosphere has been presented here. The model deals with the electromagnetic responses of the atmosphere simulated through Maxwell's equations together with a time-varying source charge distribution. The modified ellipsoidal-Gaussian profile has been taken for the charge distribution of the electrified cloud. The conductivity profile of the medium is taken to be isotropic below 70 km height and anisotropic above 70 km. The Earth's surface is considered to be perfectly conducting. A general form of equation representing the thundercloud electric field component is deduced. In spite of assumptions for axial symmetry of thundercloud charge distribution considered in the model, the results are obtained giving the electric field variation in the upper atmosphere. The vertical component of the electric field would relate the global electric circuit while the radial component showed the electrical coupling between the lower atmosphere and the ionized Earth's environment. The variations of the values of field components for different heights as well as Maxwell's current have been evaluated. Coupling between the troposphere and the ionosphere is critically dependent on the height variations of electrical conductivity. Field-aligned electron density irregularities in the ionosphere may be investigated through the present analyses.

  8. On the Vertigo Due to Static Magnetic Fields

    PubMed Central

    Mian, Omar S.; Li, Yan; Antunes, Andre; Glover, Paul M.; Day, Brian L.

    2013-01-01

    Vertigo is sometimes experienced in and around MRI scanners. Mechanisms involving stimulation of the vestibular system by movement in magnetic fields or magnetic field spatial gradients have been proposed. However, it was recently shown that vestibular-dependent ocular nystagmus is evoked when stationary in homogenous static magnetic fields. The proposed mechanism involves Lorentz forces acting on endolymph to deflect semicircular canal (SCC) cupulae. To investigate whether vertigo arises from a similar mechanism we recorded qualitative and quantitative aspects of vertigo and 2D eye movements from supine healthy adults (n = 25) deprived of vision while pushed into the 7T static field of an MRI scanner. Exposures were variable and included up to 135s stationary at 7T. Nystagmus was mainly horizontal, persisted during long-exposures with partial decline, and reversed upon withdrawal. The dominant vertiginous perception with the head facing up was rotation in the horizontal plane (85% incidence) with a consistent direction across participants. With the head turned 90 degrees in yaw the perception did not transform into equivalent vertical plane rotation, indicating a context-dependency of the perception. During long exposures, illusory rotation lasted on average 50 s, including 42 s whilst stationary at 7T. Upon withdrawal, perception re-emerged and reversed, lasting on average 30 s. Onset fields for nystagmus and perception were significantly correlated (p<.05). Although perception did not persist as long as nystagmus, this is a known feature of continuous SSC stimulation. These observations, and others in the paper, are compatible with magnetic-field evoked-vertigo and nystagmus sharing a common mechanism. With this interpretation, response decay and reversal upon withdrawal from the field, are due to adaptation to continuous vestibular input. Although the study does not entirely exclude the possibility of mechanisms involving transient vestibular stimulation

  9. Alignment of atmospheric mineral dust due to electric field

    NASA Astrophysics Data System (ADS)

    Ulanowski, Z.; Bailey, J.; Lucas, P. W.; Hough, J. H.; Hirst, E.

    2007-09-01

    Optical polarimetry observations on La Palma, Canary Islands, during a Saharan dust episode show dichroic extinction consistent with the presence of vertically aligned particles in the atmosphere. Modelling of the extinction together with particle orientation indicates that the alignment could have been due to an electric field of the order of 2 kV/m. Two alternative mechanisms for the origin of the field are examined: the effect of reduced atmospheric conductivity and charging of the dust layer, the latter effect being a more likely candidate. It is concluded that partial alignment may be a common feature of Saharan dust layers. The modelling also indicates that the alignment can significantly alter dust optical depth. This "Venetian blind effect" may have decreased optical thickness in the vertical direction by as much as 10% for the case reported here.

  10. Coherent Excited States in Superconductors due to a Microwave Field.

    PubMed

    Semenov, A V; Devyatov, I A; de Visser, P J; Klapwijk, T M

    2016-07-22

    We describe theoretically the depairing effect of a microwave field on diffusive s-wave superconductors. The ground state of the superconductor is altered qualitatively in analogy to the depairing due to a dc current. In contrast to dc depairing, the density of states acquires, for microwaves with frequency ω_{0}, steps at multiples of the photon energy Δ±nℏω_{0} and shows an exponential-like tail in the subgap regime. We show that this ac depairing explains the measured frequency shift of a superconducting resonator with microwave power at low temperatures. PMID:27494495

  11. Gravitational vacuum polarization phenomena due to the Higgs field

    NASA Astrophysics Data System (ADS)

    Onofrio, Roberto

    2012-05-01

    In the standard model the mass of elementary particles is considered as a dynamical property emerging from their interaction with the Higgs field. We show that this assumption implies peculiar deviations from the law of universal gravitation in its distance and mass dependence, as well as from the superposition principle. The experimental observation of the predicted deviations from the law of universal gravitation seems out of reach. However, we argue that a new class of experiments aimed at studying the influence of surrounding masses on the gravitational force—similar to the ones performed by Quirino Majorana almost a century ago—could be performed to test the superposition principle and to give direct limits on the presence of nonminimal couplings between the Higgs field and the spacetime curvature. From the conceptual viewpoint, the violation of the superposition principle for gravitational forces due to the Higgs field creates a conflict with the notion that gravitational potentials, as assumed in Newtonian gravitation or in post-Newtonian parameterizations of metric theories, are well-defined concepts to describe gravity in their non-relativistic limit.

  12. Report of Field Test Evaluation.

    ERIC Educational Resources Information Center

    Michigan State Univ., East Lansing. Regional Instructional Materials Center for Handicapped Children and Youth.

    Reported by the Great Lakes Region Special Education Instructional Materials Center are field test evaluation of 18 auditory instructional materials for use with handicapped children who learn best through the auditory modality. Among materials evaluated are a taped program on use of the abacus and a cassette audiotape on bird habits and sounds.…

  13. Biological effects due to weak magnetic fields on plants

    NASA Astrophysics Data System (ADS)

    Belyavskaya, N.

    In the evolution process, living organisms have experienced the action of the Earth's magnetic field (MF) that is a natural component of our environment. It is known that a galactic MF induction does not exceed 0.1 nT, since investigations of weak magnetic field (WMF) effects on biological systems have attracted attention of biologists due to planning long-term space flights to other planets where the magnetizing force is near 10-5 Oe. However, the role of WMF and its influence on organisms' functioning are still insufficiently investigated. A large number of experiments with seedlings of different plant species placed in WMF has found that the growth of their primary roots is inhibited during the early terms of germination in comparison with control. The proliferation activity and cell reproduction are reduced in meristem of plant roots under WMF application. The prolongation of total cell reproductive cycle is registered due to the expansion of G phase in1 different plant species as well as of G phase in flax and lentil roots along with2 relative stability of time parameters of other phases of cell cycle. In plant cells exposed to WMF, the decrease in functional activity of genome at early prereplicate period is shown. WMF causes the intensification in the processes of proteins' synthesis and break-up in plant roots. Qualitative and quantitative changes in protein spectrum in growing and differentiated cells of plant roots exposed to WMF are revealed. At ultrastructural level, there are observed such ultrastructural peculiarities as changes in distribution of condensed chromatin and nucleolus compactization in nuclei, noticeable accumulation of lipid bodies, development of a lytic compartment (vacuoles, cytosegresomes and paramural bodies), and reduction of phytoferritin in plastids in meristem cells of pea roots exposed to WMF. Mitochondria are the most sensitive organelle to WMF application: their size and relative volume in cells increase, matrix is electron

  14. Evaluating cotton stripper field performance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton strippers are used primarily in the Southern High Plains due to the specific cotton varieties grown. Typically, cotton strippers cost about two-thirds the price of a cotton picker and range from one-half to one-fourth the horsepower. A cotton stripper also has a higher field and harvesting ef...

  15. Evaluating and minimizing noise impact due to aircraft flyover

    NASA Technical Reports Server (NTRS)

    Jacobson, I. D.

    1980-01-01

    The results of a study on the evaluation and reduction of noise impact to a community due to aircraft landing and takeoff operations are presented. The case of multiple aircrafts flying on several trajectories, for either approach/landings or takeoffs was examined. An extremely realistic model of the flight path was developed. The annoyance criterion used was the noise impact index (NII). The algorithm was applied to Patrick Henry International Airport.

  16. Students drop out of STEM fields due to poor grades

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-09-01

    College students planning to major in science, technology, engineering, and mathematics (STEM) fields often drop out of those fields because of poorer than expected grades, according to a recent study. Conducted by Ralph Stinebrickner of Berea College in Kentucky and Todd Stinebrickner of the University of Western Ontario, the study is a National Bureau of Economic Research working paper published in June 2013.

  17. Currents and electric fields in the ionosphere due to field-aligned auroral currents

    NASA Technical Reports Server (NTRS)

    Nisbet, J. S.; Miller, M. J.; Carpenter, L. A.

    1978-01-01

    Birkeland (1908, 1913) did a detailed analysis of the upper atmospheric current system in the high-latitude region, and suggested that field-aligned currents flowing into and out of the auroral ionosphere were the driving mechanism for this current system. In the present paper, static electric field and current patterns due to the field-aligned Birkeland currents are examined, using a model in which currents approximating those reported by Iijima and Potemra (1976) are used as input to a global model of the ionospheric conductivities, in which interhemispheric coupling along field lines is included. The model reproduces the main features of the high-latitude current and voltage system and the penetration of these currents within the plasmasphere.

  18. V-fields due latest monitoring, control technology

    SciTech Connect

    Not Available

    1987-06-29

    Conoco (U.K.) Ltd. this spring begins the installation phase of its V-fields project in the southern basin of the British North Sea. A feature of the $1.25 billion project to develop the Vulcan, North and South Valiant, and Vanguard fields will be one of the most sophisticated control and monitoring systems in the North Sea. The Calcam system (Computer Assisted Logic Control and Monitoring) was designed, developed, and manufactured by Conoco U.K.'s southern offshore operations division. Calcam was first operated successfully on Conoco's Victor and Viking facilities in 1984. The V-fields are about 15 miles west of the Victor and Viking developments. Conoco is installing a central gas gathering complex which will handle the output from two unmanned satellite wellhead drilling platforms on the Vulcan field, two on North Valiant, and one each of Vanguard and South Valiant. The three fields have combined reserves of about 1.4 tcf. Gas will be delivered to Conoco's existing reception terminal on the coast of Lincolnshire at Theddlethorpe which handles gas from the Viking and Victor fields.

  19. Enhanced nucleation fields due to dipolar interactions in nanocomposite magnets

    NASA Astrophysics Data System (ADS)

    Fischbacher, Johann; Bance, Simon; Exl, Lukas; Gusenbauer, Markus; Oezelt, Harald; Reichel, Franz; Schrefl, Thomas

    2013-03-01

    One approach to construct powerful permanent magnets while using less rare-earth elements is to combine a hard magnetic material having a high coercive field with a soft magnetic material having a high saturation magnetization at the nanometer scale and create so-called nanocomposite magnets. If both materials are strongly coupled, exchange forces will form a stable magnet. We use finite element micromagnetics simulations to investigate the changing hysteresis properties for varying arrays of soft magnetic spherical inclusions in a hard magnetic body. We show that the anisotropy arising from dipolar interactions between soft magnetic particles in a hard magnetic matrix can enhance the nucleation field by more than 10% and strongly depends on the arrangement of the inclusions.

  20. Evaluation Model of Life Loss Due to Dam Failure

    NASA Astrophysics Data System (ADS)

    Huang, Dongjing

    2016-04-01

    Dam failure poses a serious threat to human life, however there is still lack of systematic research on life loss which due to dam failure in China. From the perspective of protecting human life, an evaluation model for life loss caused by dam failure is put forward. The model building gets three progressive steps. Twenty dam failure cases in China are preferably chosen as the basic data, considering geographical location and construction time of dams, as well as various conditions of dam failure. Then twelve impact factors of life loss are selected, including severity degree of flood, population at risk, understanding of dam failure, warning time, evacuation condition, number of damaged buildings, water temperature, reservoir storage, dam height, dam type, break time and distance from flood area to dam. And through principal component analysis, it gets four principal components consisting of the first flood character principle component, the second warning system principle component, the third human character principle component and the fourth space-time impact principle component. After multivariate nonlinear regression and ten-fold validation in combination, the evaluation model for life loss is finally established. And the result of the proposed model is closer to the true value and better in fitting effect in comparison with the results of RESCDAM method and M. Peng method. The proposed model is not only applied to evaluate life loss and its rate under various kinds of dam failure conditions in China, but also provides reliable cause analysis and prediction approach to reduce the risk of life loss.

  1. Evaluation of workers exposure to magnetic fields

    NASA Astrophysics Data System (ADS)

    Canova, A.; Freschi, F.; Repetto, M.

    2010-11-01

    Following ICNIRP Guidelines of 1998, European Parliament in 2004 has stated the reference levels for workers exposure to electromagnetic fields. In low frequency regime, due to the nature of the basic mechanism of short term interaction, the exposure limits are based on the values of induced eddy currents inside human body, thus electromagnetic simulation is an important tool for the assessment of electromagnetic field exposure. This paper presents a method for computing eddy currents inside human body and applies the method to the evaluation of eddy currents induced by a resistance spot welding system. A comparison between results obtained with two different models of human body and with different discretization levels is performed and results are discussed.

  2. Aerodynamic sound generation due to vortex-aerofoil interaction. Part 2: Analysis of the acoustic field

    NASA Technical Reports Server (NTRS)

    Parasarathy, R.; Karamcheti, K.

    1972-01-01

    The Lighthill method was the basic procedure used to analyze the sound field associated with a vortex of modified strength interacting with an airfoil. A free vortex interacting with an airfoil in uniform motion was modeled in order to determine the sound field due to all the acoustic sources, not only on the airfoil surfaces (dipoles), but also the ones distributed on the perturbed flow field (quadrupoles) due to the vortex-airfoil interaction. Because inviscid flow is assumed in the study of the interaction, the quadrupoles considered in the perturbed flow field are entirely due to an unsteady flow field. The effects of airfoil thickness on the second radiation are examined by using a symmetric Joukowski airfoil for the vortex-airfoil interaction. Sound radiation in a plane, far field simplification, and computation of the sound field are discussed.

  3. Ground penetrating radar field evaluation in Angola

    NASA Astrophysics Data System (ADS)

    Walls, Richard; Brown, Todd; Clodfelter, Fred; Coors, Jeff; Laudato, Stephen; Lauziere, Steve; Patrikar, Ajay; Poole, Michael; Price, Mike

    2006-05-01

    Deminers around the globe are still using handheld metal detectors that lack the capability to distinguish mines from clutter, detect mines containing very little metal, or find mines buried at deeper depths. In the southern African country of Angola, many areas and roads are impassable due to the threat of anti-tank landmines. Some of these mines are undetectable using current metal detector technology. The US Army has funded the development of the NIITEK ground penetrating radar (GPR) for detection of anti-tank (AT) landmines. This radar detects metal and plastic mines as well as mines that are buried too deep for handheld metal detectors to find. The US Department of Defense Humanitarian Demining (HD) Research & Development Program focuses on developing, testing, demonstrating, and validating new technology for immediate use in humanitarian demining operations around the globe. The HD team provided funding and guidance to NIITEK Incorporated for development of a prototype system called Mine Stalker - a relatively light-weight, remote-controlled vehicle outfitted with the NIITEK GPR, detection algorithms, and a marking system. Individuals from the HD team, NIITEK Inc, and the non-governmental organization Meschen Gegen Minen (MgM) participated in a field evaluation of the Mine Stalker in Angola. The primary aim was to evaluate the effectiveness and reliability of the NIITEK GPR under field conditions. The Mine Stalker was extremely reliable during the evaluation with no significant maintenance issues. All AT mines used to verify GPR performance were detected, even when buried to depths as deep as 25-33cm.

  4. Evaluating and minimizing noise impact due to aircraft flyover

    NASA Technical Reports Server (NTRS)

    Jacobson, I. D.; Cook, G.

    1979-01-01

    Existing techniques were used to assess the noise impact on a community due to aircraft operation and to optimize the flight paths of an approaching aircraft with respect to the annoyance produced. Major achievements are: (1) the development of a population model suitable for determining the noise impact, (2) generation of a numerical computer code which uses this population model along with the steepest descent algorithm to optimize approach/landing trajectories, (3) implementation of this optimization code in several fictitious cases as well as for the community surrounding Patrick Henry International Airport, Virginia.

  5. Field Evaluation of Programmable Thermostats

    SciTech Connect

    Sachs, O.; Tiefenbeck, V.; Duvier, C.; Qin, A.; Cheney, K.; Akers, C.; Roth, K.

    2012-12-01

    Prior research suggests that poor programmable thermostats usability may prevent their effective use to save energy. We hypothesized that home occupants with a high-usability thermostats would be more likely to use them to save energy than people with a basic thermostat. We randomly installed a high-usability thermostat in half the 77 apartments of an affordable housing complex, installing a basic thermostat in the other half. During the heating season, we collected space temperature and furnace on-off data to evaluate occupant interaction with the thermostats, foremost nighttime setbacks. We found that thermostat usability did not influence energy-saving behaviors, finding no significant difference in temperature maintained among apartments with high- and low-usability thermostats.

  6. Evaluating small-body landing hazards due to blocks

    NASA Astrophysics Data System (ADS)

    Ernst, C.; Rodgers, D.; Barnouin, O.; Murchie, S.; Chabot, N.

    2014-07-01

    Introduction: Landed missions represent a vital stage of spacecraft exploration of planetary bodies. Landed science allows for a wide variety of measurements essential to unraveling the origin and evolution of a body that are not possible remotely, including but not limited to compositional measurements, microscopic grain characterization, and the physical properties of the regolith. To date, two spacecraft have performed soft landings on the surface of a small body. In 2001, the Near Earth Asteroid Rendezvous (NEAR) mission performed a controlled descent and landing on (433) Eros following the completion of its mission [1]; in 2005, the Hayabusa spacecraft performed two touch-and-go maneuvers at (25143) Itokawa [2]. Both landings were preceded by rendezvous spacecraft reconnaissance, which enabled selection of a safe landing site. Three current missions have plans to land on small bodies (Rosetta, Hayabusa 2, and OSIRIS-REx); several other mission concepts also include small-body landings. Small-body landers need to land at sites having slopes and block abundances within spacecraft design limits. Due to the small scale of the potential hazards, it can be difficult or impossible to fully characterize a landing surface before the arrival of the spacecraft at the body. Although a rendezvous mission phase can provide global reconnaissance from which a landing site can be chosen, reasonable a priori assurance that a safe landing site exists is needed to validate the design approach for the spacecraft. Method: Many robotic spacecraft have landed safely on the Moon and Mars. Images of these landing sites, as well as more recent, extremely high-resolution orbital datasets, have enabled the comparison of orbital block observations to the smaller blocks that pose hazards to landers. Analyses of the Surveyor [3], Viking 1 and 2, Mars Pathfinder, Phoenix, Spirit, Opportunity, and Curiosity landing sites [4--8] have indicated that for a reasonable difference in size (a factor

  7. Near-field induction heating of metallic nanoparticles due to infrared magnetic dipole contribution

    NASA Astrophysics Data System (ADS)

    Chapuis, Pierre-Olivier; Laroche, Marine; Volz, Sebastian; Greffet, Jean-Jacques

    2008-03-01

    We revisit the electromagnetic heat transfer between a metallic nanoparticle and a highly conductive metallic semi-infinite substrate, commonly studied using the electric dipole approximation. For infrared and microwave frequencies, we find that the magnetic polarizability of the particle is larger than the electric one. We also find that the local density of states in the near field is dominated by the magnetic contribution. As a consequence, the power absorbed by the particle in the near field is due to dissipation by fluctuating eddy currents. These results show that a number of near-field effects involving metallic particles should be affected by the fluctuating magnetic fields.

  8. Field evaluation of a humic product in Iowa corn fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The benefit to corn production of a humic product derived from lignite was evaluated for three years under otherwise conventional crop management in Iowa farmers’ fields. Humic material was applied as a liquid extract at a rate of 3 pints acre-1 (0.57 L ha-1), generally as a foliar spray along with ...

  9. Dielectrophoretic sphere-wall repulsion due to a uniform electric field.

    PubMed

    Yariv, Ehud

    2016-07-20

    When a zero-net-charge particle is placed under a uniform electric field, the decay of the Maxwell stress with the third power of distance ensures a nil electric force. A nonzero force may nonetheless be generated in the presence of a planar wall due to a mechanism which resembles conventional dielectrophoresis under nonuniform fields. In the prototypical case of a spherical particle this force acts perpendicular to the wall; its magnitude depends upon the pertinent boundary conditions governing the electric potential. When a particle is suspended in an electrolyte solution, where the double-layer structure ensures zero net charge, these conditions are electrokinetic in nature; they involve a balance between bulk conduction and diffusion, represented by normal derivatives, and an effective surface-conduction mechanism, represented by surface-Laplacian terms whose magnitude is quantified by appropriate Dukhin numbers. The dimensionless force depends upon the particle and wall Dukhin numbers as well as the ratio λ of the size of the particle to its distance from the wall. The remote-particle limit λ ≪ 1 is addressed using successive reflections. Calculation of the first few terms in the asymptotic expansion of the force only requires the evaluation of a single reflection from the wall. The leading-order term, scaling as λ(4), is repulsive, with a magnitude that varies non-monotonically with the particle Dukhin number and is independent of the wall Dukhin number. Surface conditions on the wall enter only at the O(λ(5)) leading-order correction. PMID:27384257

  10. Evaluation of near-field earthquake effects

    SciTech Connect

    Shrivastava, H.P.

    1994-11-01

    Structures and equipment, which are qualified for the design basis earthquake (DBE) and have anchorage designed for the DBE loading, do not require an evaluation of the near-field earthquake (NFE) effects. However, safety class 1 acceleration sensitive equipment such as electrical relays must be evaluated for both NFE and DBE since they are known to malfunction when excited by high frequency seismic motions.

  11. ANALYSIS OF HIGH FIELD NON-LINEAR LOSSES ON SRF SURFACES DUE TO SPECIFIC TOPOGRAPHIC ROUGHNESS

    SciTech Connect

    Chen Xu,Charles Reece,Michael Kelley

    2012-07-01

    The high-field performance of SRF cavities will eventually be limited by the realization of fundamental material limits, whether it is Hc1 or Hsh, or some derivative thereof, at which the superconductivity is lost. Before reaching this fundamental field limit at the macro level, it must be encountered at localized, perhaps microscopic, sites of field enhancement due to local topography. If such sites are small enough, they may produce thermally stabilized normal-conducting regions which contribute non-linear losses when viewed from the macro resonant field perspective, and thus produce degradation in Q0. We have undertaken a calculation of local surface magnetic field enhancement from specific fine topographic structure by conformal mapping method and numerically. A solution of the resulting normal conducting volume has been derived and the corresponding RF Ohmic loss simulated.

  12. Deformation of a nearly hemispherical conducting drop due to an electric field: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Corson, L. T.; Tsakonas, C.; Duffy, B. R.; Mottram, N. J.; Sage, I. C.; Brown, C. V.; Wilson, S. K.

    2014-12-01

    We consider, both theoretically and experimentally, the deformation due to an electric field of a pinned nearly hemispherical static sessile drop of an ionic fluid with a high conductivity resting on the lower substrate of a parallel-plate capacitor. Using both numerical and asymptotic approaches, we find solutions to the coupled electrostatic and augmented Young-Laplace equations which agree very well with the experimental results. Our asymptotic solution for the drop interface extends previous work in two ways, namely, to drops that have zero-field contact angles that are not exactly π/2 and to higher order in the applied electric field, and provides useful predictive equations for the changes in the height, contact angle, and pressure as functions of the zero-field contact angle, drop radius, surface tension, and applied electric field. The asymptotic solution requires some numerical computations, and so a surprisingly accurate approximate analytical asymptotic solution is also obtained.

  13. Modeling Long-Term Soil Losses on Agricultural Fields Due to Ephemeral Gully Erosion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is now recognized worldwide that soil erosion on agricultural fields due to ephemeral gullies may be greater than those losses attributed to sheet and rill erosion processes. Yet it is not known whether the common practice of repairing or obliterating these gullies during annual tillage activitie...

  14. Melt Motion Due to Peltier Marking During Bridgman Crystal Growth with an Axial Magnetic Field

    NASA Technical Reports Server (NTRS)

    Sellers, C. C.; Walker, John S.; Szofran, Frank R.; Motakef, Shariar

    2000-01-01

    This paper treats a liquid-metal flow inside an electrically insulating cylinder with electrically conducting solids above and below the liquid region. There is a uniform axial magnetic field, and there is an electric current through the liquid and both solids. Since the lower liquid-solid interface is concave into the solid and since the liquid is a better electrical conductor than the adjacent solid, the electric current is locally concentrated near the centerline. The return to a uniform current distribution involves a radial electric current which interacts with the axial magnetic field to drive an azimuthal flow. The axial variation of the centrifugal force due to the azimuthal velocity drives a meridional circulation with radial and axial velocities. This problem models the effects of Peltier marking during the vertical Bridgman growth of semiconductor crystals with an externally applied magnetic field, where the meridional circulation due to the Peltier Current may produce important mixing in the molten semiconductor.

  15. Surface potential at a ferroelectric grain due to asymmetric screening of depolarization fields

    SciTech Connect

    Genenko, Yuri A. Hirsch, Ofer; Erhart, Paul

    2014-03-14

    Nonlinear screening of electric depolarization fields, generated by a stripe domain structure in a ferroelectric grain of a polycrystalline material, is studied within a semiconductor model of ferroelectrics. It is shown that the maximum strength of local depolarization fields is rather determined by the electronic band gap than by the spontaneous polarization magnitude. Furthermore, field screening due to electronic band bending and due to presence of intrinsic defects leads to asymmetric space charge regions near the grain boundary, which produce an effective dipole layer at the surface of the grain. This results in the formation of a potential difference between the grain surface and its interior of the order of 1 V, which can be of either sign depending on defect transition levels and concentrations. Exemplary acceptor doping of BaTiO{sub 3} is shown to allow tuning of the said surface potential in the region between 0.1 and 1.3 V.

  16. Field evaluation of Bemisia parasitoids in Texas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two methods were employed to assess the potential of candidate parasitoid species/strains to parasitize B. tabaci under field conditions in Texas. Sleeve cage evaluations were conducted in kale, cantaloupe melons, and cotton in 1994–1995. In kale, the highest parasitism rates were observed for two s...

  17. Electric field variations due to resonance between ground velocity and ions motion in the Earth's magnetic field

    NASA Astrophysics Data System (ADS)

    Matsushima, M.; Honkura, Y.; Kuriki, M.; Ogawa, Y.

    2011-12-01

    We have so far observed clear electric field variations coincident with the passage of seismic waves. Circular polarization of electric field is the distinguishing feature in this phenomenon which can be interpreted in terms of the so-called seismic dynamo effect proposed by Honkura et al. (2009). That is, circularly polarized electric field is caused by resonance-like motion of ion in groundwater under the Earth's magnetic field. Therefore, left-handed and right-handed circular polarizations, if seen towards the direction of the magnetic field, are associated with anions with negative charge and cations with positive charge, respectively. Such polarization may be inconsistent with seismoelectric signals due to the electrokinetic mechanism, because they are mainly found in the direction of transmission of seismic compressional waves, as pointed out by Strahser et al. (2007) who examined polarization of seismoelectric signals by recording the three components of electric field. However, even such circular polarization of electric field is somehow interpreted in terms of the electrokinetic mechanism. Therefore, further convincing evidence is required to support the seismic dynamo effect. On 25-26 July 2011, an experiment for studies of crustal seismic structure was made in central Japan. We carried out simultaneous observations of ground velocity and electric field on this occasion at three sites near a blasting point using 50 kg of dynamite; about 280 m east-southeast, about 190 m east, and about 360 m northwest from the blasting point. Taking into account typical frequencies of ground velocity for artificial earthquakes by blasting higher than those for natural earthquakes, we used data loggers with sampling rate of 1 kHz and could obtain the waveforms of ground velocity and electric field very clearly. We show characteristics of electric field variations, their dependence of azimuth angle with respect to the blasting point, and frequency response functions.

  18. Evaluation of military field-water quality

    SciTech Connect

    Daniels, J.I.; Gallegos, G.M.

    1990-05-01

    This is the first and summary volume of the nine-volume study entitled Evaluation of Military Field-Water Quality. This study is a comprehensive assessment of the chemical, radiological, and biological constituents of field-water supplied that could pose health risks to military personnel around the world; it also provides a detailed evaluation of the field-water-treatment capability of the US Armed Forces. This study identifies as being of concern three physical properties, i.e., turbidity, color, and total dissolved solids; seven chemical constituents, i.e., chloride, magnesium, sulfate, arsenic, cyanide, lindane, and metabolites of algae and associated aquatic bacteria; and over twenty types of water-related pathogenic microorganisms. It also addresses five threat agents, i.e., hydrogen cyanide, radioactivity, organophosphorous nerve agents, the trichotecene mycotoxin T-2, and lewisite. An overview of the criteria and recommendations for standards for these constituents for short- term and long-term exposure periods are presented in this volume, as are health-effects summaries for assessing the potential soldier performance degradation when recommended standards are exceeded. In addition, the existing military field-water-treatment capability is reviewed, and an abbreviated discussion is presented of the general physical, chemical, and biological qualities of field waters in geographic regions worldwide, representing potential theaters of operation for US military forces. Finally, research recommendations are outlined. 18 figs., 6 tabs.

  19. Dynamical Effects Due to Fringe Field of the Magnets in Circular Accelerators

    SciTech Connect

    Cai, Y.; Nosochkov, Yu.; /SLAC

    2005-05-16

    The leading Lie generators, including the chromatic effects, due to hard-edge fringe field of single multipole and solenoid are derived from the vector potentials within a Hamiltonian system. These nonlinear generators are applied to the interaction region of PEP-II to analyze the linear errors due to the feed-down from the off-centered quadrupoles and solenoid. The nonlinear effects of tune shifts at large amplitude, the synchro-betatron sidebands near half integer and their impacts on the dynamic aperture are studied in the paper.

  20. Frequency shifts in NIST Cs primary frequency standards due to transverse rf field gradients

    NASA Astrophysics Data System (ADS)

    Ashby, Neil; Barlow, Stephan; Heavner, Thomas; Jefferts, Steven

    2015-03-01

    A single-particle Green's function (propagator) is introduced to study the deflection of laser-cooled cesium atoms in an atomic fountain due to microwave magnetic field gradients in the Ramsey TE011 cavity. The deflection results in a state-dependent loss of atoms at apertures in the physics package, resulting in a frequency bias. A model accounting only for motion in one dimension transverse to the symmetry axis of the fountain is discussed in detail and then generalized to two transverse dimensions. Results for fractional frequency shifts due to transverse field gradients are computed for NIST-F1 and NIST-F2 cesium fountains. The shifts are found to be negligible except in cases of higher rf power applied to the cavities.

  1. The magnetic field inside a layered anisotropic spherical conductor due to internal sources

    NASA Astrophysics Data System (ADS)

    Nieminen, Jaakko O.; Stenroos, Matti

    2016-01-01

    Recent advances in neuronal current imaging using magnetic resonance imaging and in invasive measurement of neuronal magnetic fields have given a need for methods to compute the magnetic field inside a volume conductor due to source currents that are within the conductor. In this work, we derive, verify, and demonstrate an analytical expression for the magnetic field inside an anisotropic multilayer spherically symmetric conductor due to an internal current dipole. We casted an existing solution for electric field to vector spherical harmonic (VSH) form. Next, we wrote an ansatz for the magnetic field using toroidal-poloidal decomposition that uses the same VSHs. Using properties of toroidal and poloidal components and VSHs and applying magnetic scalar potential, we then formulated a series expression for the magnetic field. The convergence of the solution was accelerated by formulating the solution using an addition-subtraction method. We verified the resulting formula against boundary-element method. The verification showed that the formulas and implementation are correct; 99th percentiles of amplitude and angle differences between the solutions were below 0.5% and 0.5°, respectively. As expected, the addition-subtraction model converged faster than the unaccelerated model; close to the source, 250 terms gave relative error below 1%, and the number of needed terms drops fast, as the distance to the source increases. Depending on model conductivities and source position, field patterns inside a layered sphere may differ considerably from those in a homogeneous sphere. In addition to being a practical modeling tool, the derived solution can be used to verify numerical methods, especially finite-element method, inside layered anisotropic conductors.

  2. Field collapse due to band-tail charge in amorphous silicon solar cells

    SciTech Connect

    Wang, Qi; Crandall, R.S.; Schiff, E.A.

    1996-05-01

    It is common for the fill factor to decrease with increasing illumination intensity in hydrogenated amorphous silicon solar cells. This is especially critical for thicker solar cells, because the decrease is more severe than in thinner cells. Usually, the fill factor under uniformly absorbed red light changes much more than under strongly absorbed blue light. The cause of this is usually assumed to arise from space charge trapped in deep defect states. The authors model this behavior of solar cells using the Analysis of Microelectronic and Photonic Structures (AMPS) simulation program. The simulation shows that the decrease in fill factor is caused by photogenerated space charge trapped in the band-tail states rather than in defects. This charge screens the applied field, reducing the internal field. Owing to its lower drift mobility, the space charge due to holes exceeds that due to electrons and is the main cause of the field screening. The space charge in midgap states is small compared with that in the tails and can be ignored under normal solar-cell operating conditions. Experimentally, the authors measured the photocapacitance as a means to probe the collapsed field. They also explored the light intensity dependence of photocapacitance and explain the decrease of FF with the increasing light intensity.

  3. Entry control technology biometric field evaluations

    SciTech Connect

    Rodriguez, J.R.; Ahrens, J.S.; Lowe, D.L.

    1995-07-01

    Throughout the years, Sandia National Laboratories (SNL) has performed various laboratory evaluations of entry control devices, including biometric identity verifiers. The reports which resulted from this testing have been very well received by the physical security community. This same community now requires equally informative field study data. To meet this need we have conducted a field study in an effort to develop the tools and methods which our customers can use to translate laboratory data into operational field performance. The field testing described in this report was based on the Recognition Systems Inc.`s (RSI) model ID3D HandKey biometric verifier. This device was selected because it is referenced in DOE documents such as the Guide for Implementation of the DOE Standard Badge and is the de facto biometric standard for the DOE. The ID3D HandKey is currently being used at several DOE sites such as Hanford, Rocky Flats, Pantex, Savannah River, and Idaho Nuclear Engineering Laboratory. The ID3D HandKey was laboratory tested at SNL. It performed very well during this test, exhibiting an equal error point of 0.2 percent. The goals of the field test were to identify operational characteristics and design guidelines to help system engineers translate laboratory data into field performance. A secondary goal was to develop tools which could be used by others to evaluate system effectiveness or improve the performance of their systems. Operational characteristics were determined by installing a working system and studying its operation over a five month period. Throughout this test we developed tools which could be used by others to similarly gauge system effectiveness.

  4. Enhancement of the thermoelectric figure of merit in a quantum dot due to external ac field

    NASA Astrophysics Data System (ADS)

    Chen, Qiao; Wang, Zhi-yong; Xie, Zhong-Xiang

    2013-08-01

    We investigate the figure of merit of a quantum dot (QD) system irradiated with an external microwave filed by nonequilibrium Green's function (NGF) technique. Results show that the frequency of microwave field influence the figure of merit ZT significantly. At low temperature, a sharp peak can be observed in the figure of merit ZT as the frequency of ac field increases. As the frequency varies, several zero points and resonant peaks emerge in the figure of merit ZT. By adjusting the frequency of the microwave field, we can obtain high ZT. The figure of merit ZT increases with the decreasing of linewidth function Γ. In addition, Wiedemann-Franz law does not hold, particularly in the low frequency region due to multi-photon emission and absorption. Some novel thermoelectric properties are also found in two-level QD system.

  5. Plasma heating at collisionless shocks due to the kinetic cross-field streaming instability

    NASA Technical Reports Server (NTRS)

    Winske, D.; Quest, K. B.; Tanaka, M.; Wu, C. S.

    1985-01-01

    Heating at collisionless shocks due to the kinetic cross-field streaming instability, which is the finite beta (ratio of plasma to magnetic pressure) extension of the modified two stream instability, is studied. Heating rates are derived from quasi-linear theory and compared with results from particle simulations to show that electron heating relative to ion heating and heating parallel to the magnetic field relative to perpendicular heating for both the electrons and ions increase with beta. The simulations suggest that electron dynamics determine the saturation level of the instability, which is manifested by the formation of a flattop electron distribution parallel to the magnetic field. As a result, both the saturation levels of the fluctuations and the heating rates decrease sharply with beta. Applications of these results to plasma heating in simulations of shocks and the earth's bow shock are described.

  6. Field site evaluation for seismic mine detection

    NASA Astrophysics Data System (ADS)

    Martin, James S.; Larson, Gregg D.; Rogers, Peter H.; Scott, Waymond R., Jr.; McCall, George S., II

    2002-11-01

    A system has been developed that uses audio-frequency surface seismic waves for the detection and imaging of buried landmines. The system is based on the measurement of seismic displacements immediately above buried mines using noncontacting vibrometers that interrogate the surface motion with either radar or ultrasonic signals. In laboratory tests and limited field tests the system has demonstrated the ability to detect a variety of inert antipersonnel and antitank mines with background contrast in excess of 20 dB. Current work on the system is focused on the transition from the laboratory into the field. To facilitate this, a series of experiments has been undertaken to measure the characteristics of several field test sites. The tradeoff between image contrast and scanning speed is of primary concern in evaluating the features of these sites. The field experiments have investigated the nature of ambient seismic noise, input impedance at the seismic source (a ground contacting shaker), modal content of the seismic interrogation signal, and the nature of the nonlinearities in the soil. Observed nonlinear phenomena have included harmonic generation, phase speed slowing, dispersion and spall. Although interesting, the differences between the field sites and the laboratory model do not appear to pose problems for seismic mine detection.

  7. Evaluating Differences in Landscape Interpretation between Webcam and Field-Based Experiences

    ERIC Educational Resources Information Center

    Kolivras, Korine N.; Luebbering, Candice R.; Resler, Lynn M.

    2012-01-01

    Field trips have become less common due to issues including budget constraints and large class sizes. Research suggests that virtual field trips can substitute for field visits, but the role of webcams has not been evaluated. To investigate the potential for webcams to substitute for field trips, participants viewed urban and physical landscapes…

  8. Revealing giant internal magnetic fields due to spin fluctuations in magnetically doped colloidal nanocrystals.

    PubMed

    Rice, William D; Liu, Wenyong; Baker, Thomas A; Sinitsyn, Nikolai A; Klimov, Victor I; Crooker, Scott A

    2016-02-01

    Strong quantum confinement in semiconductors can compress the wavefunctions of band electrons and holes to nanometre-scale volumes, significantly enhancing interactions between themselves and individual dopants. In magnetically doped semiconductors, where paramagnetic dopants (such as Mn(2+), Co(2+) and so on) couple to band carriers via strong sp-d spin exchange, giant magneto-optical effects can therefore be realized in confined geometries using few or even single impurity spins. Importantly, however, thermodynamic spin fluctuations become increasingly relevant in this few-spin limit. In nanoscale volumes, the statistical fluctuations of N spins are expected to generate giant effective magnetic fields Beff, which should dramatically impact carrier spin dynamics, even in the absence of any applied field. Here we directly and unambiguously reveal the large Beff that exist in Mn(2+)-doped CdSe colloidal nanocrystals using ultrafast optical spectroscopy. At zero applied magnetic field, extremely rapid (300-600 GHz) spin precession of photoinjected electrons is observed, indicating Beff ∼ 15 -30 T for electrons. Precession frequencies exceed 2 THz in applied magnetic fields. These signals arise from electron precession about the random fields due to statistically incomplete cancellation of the embedded Mn(2+) moments, thereby revealing the initial coherent dynamics of magnetic polaron formation, and highlighting the importance of magnetization fluctuations on carrier spin dynamics in nanomaterials. PMID:26595331

  9. Highly Effective Conductance Modulation in Planar Silicene Field Effect Devices Due to Buckling

    PubMed Central

    Al-Dirini, Feras; Hossain, Faruque M.; Mohammed, Mahmood A.; Nirmalathas, Ampalavanapillai; Skafidas, Efstratios

    2015-01-01

    Silicene is an exciting two-dimensional material that shares many of graphene’s electronic properties, but differs in its structural buckling. This buckling allows opening a bandgap in silicene through the application of a perpendicular electric field. Here we show that this buckling also enables highly effective modulation of silicene’s conductance by means of an in-plane electric field applied through silicene side gates, which can be realized concurrently within the same silicene monolayer. We illustrate this by using silicene to implement Self-Switching Diodes (SSDs), which are two-dimensional field effect nanorectifiers realized within a single silicene monolayer. Our quantum simulation results show that the atomically-thin silicene SSDs, with sub-10 nm dimensions, achieve a current rectification ratio that exceeds 200, without the need for doping, representing a 30 fold enhancement over graphene SSDs. We attribute this enhancement to a bandgap opening due to the in-plane electric field, as a consequence of silicene’s buckling. Our results suggest that silicene is a promising material for the realization of planar field effect devices. PMID:26441200

  10. Increase in Phi X174 DNA radiation sensitivity due to electric fields

    SciTech Connect

    McCormack, Percival D.; Swenberg, Charles E.

    1985-01-01

    The object of this research was to establish whether or not orientation of DNA in electric fields would result in a significant increase in its sensitivity to damage by ionizing radiation. The application of an external electric field simultaneously with gamma irradiation to an aqueous suspension of Phi X 174 (in the RFI form) is shown to increase significantly the number of strand breaks. Tritiated DNA allowed the number of single-strand breaks to be estimated from changes in the scintillation of electrophoretic gel band associated with the fastest mobility moiety. At 400 V ( approx. 2400 V/cm) the corrected increase (corrected for phoresis of DNA on the stainless steel plates) in the G-value yield is 38%. The increase in damage with field strength appears to follow the increase in reduced dichroism. Dichroism results correspond at 400 V to approximately 10% of the maximum orientation. These results support the conjecture that this significant increase in DNA-radiation interaction with an electric field is due to field-induced conformation changes in the molecule. Keywords: Polyelectrolytes, Polynucleotides, Polypeptides, Birefringence, Dipole, and Moments.

  11. On the gravitational potential and field anomalies due to thin mass layers

    NASA Technical Reports Server (NTRS)

    Ockendon, J. R.; Turcotte, D. L.

    1977-01-01

    The gravitational potential and field anomalies for thin mass layers are derived using the technique of matched asymptotic expansions. An inner solution is obtained using an expansion in powers of the thickness and it is shown that the outer solution is given by a surface distribution of mass sources and dipoles. Coefficients are evaluated by matching the inner expansion of the outer solution with the outer expansion of the inner solution. The leading term in the inner expansion for the normal gravitational field gives the Bouguer formula. The leading term in the expansion for the gravitational potential gives an expression for the perturbation to the geoid. The predictions given by this term are compared with measurements by satellite altimetry. The second-order terms in the expansion for the gravitational field are required to predict the gravity anomaly at a continental margin. The results are compared with observations.

  12. Field evaluation of a VOST sampling method

    SciTech Connect

    Jackson, M.D.; Johnson, L.D.; Fuerst, R.G.; McGaughey, J.F.; Bursey, J.T.; Merrill, R.G.

    1994-12-31

    The VOST (SW-846 Method 0030) specifies the use of Tenax{reg_sign} and a particular petroleum-based charcoal (SKC Lot 104, or its equivalent), that is no longer commercially available. In field evaluation studies of VOST methodology, a replacement petroleum-based charcoal has been used: candidate replacement sorbents for charcoal were studied, and Anasorb{reg_sign} 747, a carbon-based sorbent, was selected for field testing. The sampling train was modified to use only Anasorb{reg_sign} in the back tube and Tenax{reg_sign} in the two front tubes to avoid analytical difficulties associated with the analysis of the sequential bed back tube used in the standard VOST train. The standard (SW-846 Method 0030) and the modified VOST methods were evaluated at a chemical manufacturing facility using a quadruple probe system with quadruple trains. In this field test, known concentrations of the halogenated volatile organic compounds, that are listed in the Clean Air Act Amendments of 1990, Title 3, were introduced into the VOST train and the modified VOST train, using the same certified gas cylinder as a source of test compounds. Statistical tests of the comparability of methods were performed on a compound-by-compound basis. For most compounds, the VOST and modified VOST methods were found to be statistically equivalent.

  13. Evaluation of PV Module Field Performance

    SciTech Connect

    Wohlgemuth, John; Silverman, Timothy; Miller, David C.; McNutt, Peter; Kempe, Michael; Deceglie, Michael

    2015-06-14

    This paper describes an effort to inspect and evaluate PV modules in order to determine what failure or degradation modes are occurring in field installations. This paper will report on the results of six site visits, including the Sacramento Municipal Utility District (SMUD) Hedge Array, Tucson Electric Power (TEP) Springerville, Central Florida Utility, Florida Solar Energy Center (FSEC), the TEP Solar Test Yard, and University of Toledo installations. The effort here makes use of a recently developed field inspection data collection protocol, and the results were input into a corresponding database. The results of this work have also been used to develop a draft of the IEC standard for climate and application specific accelerated stress testing beyond module qualification. TEP Solar Test Yard, and University of Toledo installations. The effort here makes use of a recently developed field inspection data collection protocol, and the results were input into a corresponding database. The results of this work have also been used to develop a draft of the IEC standard for climate and application specific accelerated stress testing beyond module qualification. TEP Solar Test Yard, and University of Toledo installations. The effort here makes use of a recently developed field inspection data collection protocol, and the results were input into a corresponding database. The results of this work have also been used to develop a draft of the IEC standard for climate and application specific accelerated stress testing beyond module qualification.

  14. Platform evaluation of an offshore field

    SciTech Connect

    Huang, K.L.; Saleri, N.G.; Al-Khowaiter, A.O.

    1995-10-01

    A numerical study of an offshore field was performed to evaluate the relative performance of horizontal versus conventional wells, and various well completion/placement/production scenarios for a six-well platform. The results presented in this paper are found to be counterintuitive. While horizontal/high slant wells showed delayed gas and/or water breakthroughs, the overall platform performance remained largely insensitive to well configuration (horizontal versus conventional). Well placement, completion interval, and production strategy after breakthrough were identified to be the critical parameters in determining the performance of the platform. The study results favor conventional completions for this particular six-well platform.

  15. Field and laboratory tests on risk of slope failure due to weathering of rock materials

    NASA Astrophysics Data System (ADS)

    Qureshi, M. U.; Towhata, I.; Yamada, S.; Aziz, M.

    2009-04-01

    Authors set out the challenge to explore the mechanism of rock weathering and its effects to the geotechnical hazards. Any natural or human induced disturbances to the natural slopes speed up their weathering process. So, exploration of both disturbed and undisturbed slopes is necessary for robust understanding. Various regions in Asia were explored to experience variety of environmental and climatic conditions. Field exploration on the thickness and in-situ mechanical property was carried out by performing seismic refraction surveys, dynamic cone penetration tests and Schmidt hammer tests at various sites in Japan and Pakistan. In laboratory change in mechanical property of soft rocks due to weathering has been observed and slake durability tests were conducted on various rocks. Field exploration indicated that the thickness of weathered layer is 1 meter or its roundabouts and having S-wave velocity of 200-300 m/s. Laboratory testing differentiated the slaking potential and mechanical property degradation of various rocks. Moreover sensible correlations had been observed in thickness calculated by seismic refraction or dynamic cone penetration in field. Slake durability index showed good correlation with Schmidt hammer hardness and mechanical property. A general agreement was also observed when strength and S-wave velocities from laboratory tests were compared with the field exploration. Authors believed that the study provides the useful information on the long term prediction and assessment of landslide risk.

  16. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    NASA Astrophysics Data System (ADS)

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-07-01

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  17. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    SciTech Connect

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-07-14

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  18. Small scale changes of geochemistry and flow field due to transient heat storage in aquifers

    NASA Astrophysics Data System (ADS)

    Bauer, S.; Boockmeyer, A.; Li, D.; Beyer, C.

    2013-12-01

    Heat exchangers in the subsurface are increasingly installed for transient heat storage due to the need of heating or cooling of buildings as well as the interim storage of heat to compensate for the temporally fluctuating energy production by wind or solar energy. For heat storage to be efficient, high temperatures must be achieved in the subsurface. Significant temporal changes of the soil and groundwater temperatures however effect both the local flow field by temperature dependent fluid parameters as well as reactive mass transport through temperature dependent diffusion coefficients, geochemical reaction rates and mineral equilibria. As the use of heat storage will be concentrated in urban areas, the use of the subsurface for (drinking) water supply and heat storage will typically coincide and a reliable prognosis of the processes occurring is needed. In the present work, the effects of a temporal variation of the groundwater temperature, as induced by a local heat exchanger introduced into a groundwater aquifer, are studied. For this purpose, the coupled non-isothermal groundwater flow, heat transport and reactive mass transport is simulated in the near filed of such a heat exchanger. By explicitly discretizing and incorporating the borehole, the borehole cementation and the heat exchanger tubes, a realistic geometrical and process representation is obtained. The numerical simulation code OpenGeoSys is used in this work, which incorporates the required processes of coupled groundwater flow, heat and mass transport as well as temperature dependent geochemistry. Due to the use of a Finite Element Method, a close representation of the geometric effects can be achieved. Synthetic scenario simulations for typical settings of salt water formations in northern Germany are used to investigate the geochemical effects arising from a high temperature heat storage by quantifying changes in groundwater chemistry and overall reaction rates. This work presents the

  19. Pineal melatonin level disruption in humans due to electromagnetic fields and ICNIRP limits.

    PubMed

    Halgamuge, Malka N

    2013-05-01

    The International Agency for Research on Cancer (IARC) classifies electromagnetic fields (EMFs) as 'possibly carcinogenic' to humans that might transform normal cells into cancer cells. Owing to high utilisation of electricity in day-to-day life, exposure to power-frequency (50 or 60 Hz) EMFs is unavoidable. Melatonin is a natural hormone produced by pineal gland activity in the brain that regulates the body's sleep-wake cycle. How man-made EMFs may influence the pineal gland is still unsolved. The pineal gland is likely to sense EMFs as light but, as a consequence, may decrease the melatonin production. In this study, more than one hundred experimental data of human and animal studies of changes in melatonin levels due to power-frequency electric and magnetic fields exposure were analysed. Then, the results of this study were compared with the International Committee of Non-Ionizing Radiation Protection (ICNIRP) limit and also with the existing experimental results in the literature for the biological effect of magnetic fields, in order to quantify the effects. The results show that this comparison does not seem to be consistent despite the fact that it offers an advantage of drawing attention to the importance of the exposure limits to weak EMFs. In addition to those inconsistent results, the following were also observedfrom this work: (i) the ICNIRP recommendations are meant for the well-known acute effects, because effects of the exposure duration cannot be considered and (ii) the significance of not replicating the existing experimental studies is another limitation in the power-frequency EMFs. Regardless of these issues, the above observation agrees with our earlier study in which it was confirmed that it is not a reliable method to characterise biological effects by observing only the ratio of AC magnetic field strength to frequency. This is because exposure duration does not include the ICNIRP limit. Furthermore, the results show the significance of

  20. Estimation of Surface Roughness due to Electrode Erosion in Field-Distortion Gas Switch

    NASA Astrophysics Data System (ADS)

    Liu, Xuandong; Wang, Hu; Li, Xiaoang; Zhang, Qiaogen; Wei, Jin; Qiu, Aici

    2013-08-01

    Field distortion gas switch is one of the crucial elements in a Marx generator, fast linear transformer driver and other pulsed power installations. The performance of the gas switch, which is dramatically affected by the surface roughness due to electrode erosion during the discharge process, directly influences the output parameters, stability and reliability of the pulsed power system. In this paper, an electrode surface roughness (ESR) calculation model has been established based on a great deal of experimental data under operating current. The discharge current waveform, the peak height of the burr, the radius and the depth of etch pits in the electrode erosion region were used to predict the ESR. Also, experimental results indicate that this calculation model can effectively estimate the ESR of the test gas switch.

  1. Laboratory and field evaluation of an underwater sand height gage

    NASA Technical Reports Server (NTRS)

    Swift, D. J. P.; Mcgrath, D. G.

    1972-01-01

    An underwater sand height gage was investigated. This instrument consisted of two transducers, one screened and one unscreened. Laboratory experimentation included static and dynamic tests with three test sands--fine, medium, and coarse. Field tests were conducted at Rudee Inlet, Virginia Beach, Virginia. Test results showed a linear response to up to 10 inches of sand loading. Deviation observed in identical tests appeared to be due to variation in the density of sand. Density differences reflected varying packing styles which, in turn, were a consequence of grain size and flow regime. Further evaluations of the sand height gage reflect this instrument's potential.

  2. Field evaluation of prototype electrofibrous filters

    SciTech Connect

    Kuhl, W.D.; Bergman, W.; Biermann, A.H.; Lum, B.Y.

    1982-09-30

    New prototype electrofibrous filters were designed, built and evaluated in laboratory tests and in field installations. Two prototypes were designed for use in nuclear ventilation ducts as prefilters to HEPA filters. One prototype is designed to be a permanent component of the ventilation system while the other is a disposable unit. The disposable electrofibrous prefilter was installed in the exhaust stream of a glove box in which barrels of uranium turnings are burned. Preliminary tests show the disposal prefilter is effectively prolonging the HEPA filter life. An earlier prototype of the rolling prefilter was upgraded to meet the increased requirements for installation in a nuclear facility. This upgraded prototype was evaluated in the fire test facility at LLNL and shown to be effective in protecting HEPA filters from plugging under the most severe smoke conditions. The last prototype described in this report is a recirculating air filter. After demonstrating a high performance in laboratory tests the unit was shipped to Savannah River where it is awaiting installation in a Pu fuel fabrication facility. An analysis of the particulate problem in Savannah River indicates that four recirculating air filter will save $172,000 per year in maintenance costs.

  3. Characterising oil and water in porous media using decay due to diffusion in the internal field

    NASA Astrophysics Data System (ADS)

    Lewis, Rhiannon T.; Djurhuus, Ketil; Seland, John Georg

    2015-10-01

    In the method Decay due to Diffusion in the Internal Field (DDIF), the diffusion behaviour of water molecules in the internal magnetic field makes it possible to determine a distribution of pore sizes in a sample. The DDIF experiment can also be extended to a DDIF-Carr-Purcell-Meiboom-Gill (DDIF-CPMG) experiment to measure correlations between the pore size and the transverse relaxation time, T2 . In this study we have for the first time applied the DDIF experiment and the DDIF-CPMG experiment to porous materials saturated with both water and oil. Because of the large difference in diffusion rates between water and oil molecules, the DDIF experiment will act as a filter for the signal from oil, and we are left with the DDIF-signal from water only. This has been verified in model systems consisting of glass beads immersed in separate layers of water and oil, and in a sandstone sample saturated with water and oil. The results show that the DDIF and DDIF-CPMG experiments enable the determination of the confining geometry of the water phase, and how this geometry is correlated to T2 . Data obtained in the sandstone sample saturated with water and oil also show that with the exception of the smallest pores there is no clear correlation between pore size and the relaxation time of water.

  4. 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.

  5. Blending vocal music with a given sound field due to the characteristics of the running autocorrelation function of singing voices

    NASA Astrophysics Data System (ADS)

    Kato, Kosuke; Fujii, Kenji; Kawai, Keiji; Ando, Yoichi; Yano, Takashi

    2001-05-01

    This is a study to meet music and the opera house acoustics. It is said that singers adjust their interpretation style according to the acoustical condition of the sound field in a room. However, this mechanism of blending of musical performance with the sound field is unknown. In order to obtain a method of performance blending of opera house acoustics, we attempted to develop evaluation criteria for a singing voice in terms of the minimum value of the effective duration of the running autocorrelation function (r-ACF), (te)min, of sound source signals. This temporal factor has shown to have close correlation with the subjective response of both listeners and performers to sound fields [Y. Ando, Architectural Acoustics (AIP Press/Springer-Verlag, New York, 1998)]. As example for the control of (te)min due to performing style, effects of singing style, kind of vowel, relative pitch, vibrato extent, and intonation on the values of (te)min are demonstrated. In addition, the fine structure of the r-ACF is discussed with regard to the identification of vowels of singing voice. a)Now at 1-10-27 Yamanokami, Kumamoto, Japan.

  6. Acoustic Radiation Force on a Finite-Sized Particle due to an Acoustic Field in a Viscous Compressible Fluid

    NASA Astrophysics Data System (ADS)

    Annamalai, Subramanian; Parmar, Manoj; Balachandar, S.

    2013-11-01

    Particles when subjected to acoustic waves experience a time-averaged second-order force known as the acoustic radiation force, which is of prime importance in the fields of microfluidics and acoustic levitation. Here, the acoustic radiation force on a rigid spherical particle in a viscous compressible medium due to progressive and standing waves is considered. The relevant length scales include: particle radius (a), acoustic wavelength (λ) and viscous penetration depth (δ). While a / λ and a / δ are arbitrary, δ << λ . A farfield derivation approach has been used in determining the radiated force. Expressing the flow-field as a sum of the incident and scattered fields, an analytical expression for the force is obtained as a summation over infinite series (monopole, dipole and higher sources). These results indicate that the contributions from monopole, dipole and their cross-interaction are sufficient to describe the acoustic radiation force. Subsequently, the monopole and dipole strengths are represented in terms of the particle surface and volume averages of the incoming velocity. This generalization allows one to evaluate the radiation force for an incoming wave of any functional form. However acoustic streaming effects are neglected.

  7. Modelling and Evaluation of Environmental Impact due to Continuous Emissions of the Severonickel Plant (Kola Peninsula)

    NASA Astrophysics Data System (ADS)

    Mahura, A.; Gonzalez-Aparicio, I.; Nuterman, R.; Baklanov, A.

    2012-04-01

    In this study, evaluation of potential impact - through concentration, deposition and loadings patterns - on population and environment due to continuous anthropogenic emissions (on example of sulfates) of the Cu-Ni smelters of the Russian North is given. To estimate impact, the Danish Emergency Response Model for Atmosphere (DERMA) was employed to perform long-term simulations of air concentration, time integrated air concentration (TIAC), dry (DD) and wet (WD) deposition patterns resulting from continuous emissions of the Severonickel smelters located on the Kola Peninsula (Murmansk region, Russia). To perform such simulations the 3D meteorological fields (from the European Center for Medium-Range Weather Forecasts, ECMWF) for the year 2000 were used as input. For simplicity, it has been assumed that normalized releases of sulfates from smelters location occurred at a constant rate every day. For each daily release the atmospheric transport, dispersion, dry and wet deposition due to removal processes were estimated during 10 day interval. Output from these long-term simulations is an essential input for evaluation of impact, doses, risks, and short- and long-term consequences, etc. Detailed analyses of simulated concentration and deposition fields allowed evaluating the spatial and temporal variability of resulted patterns on different scales. Temporal variability of both wet and dry deposition as well as their contribution into total deposition have been estimated. On an annual scale, the concentration and deposition patterns were estimated for the most populated cities of the North-West Russia. The modeled annual fields were also integrated into GIS environment as well as layers with population density (from the Center for International Earth Science Information Network, CIESIN) and standard administrative division of the North-West Russia and bordering countries. Furthermore, the estimation of deposited amounts (loadings) of sulfates for selected regions of

  8. Hazardous gas model evaluation with field observations

    NASA Astrophysics Data System (ADS)

    Hanna, S. R.; Chang, J. C.; Strimaitis, D. G.

    Fifteen hazardous gas models were evaluated using data from eight field experiments. The models include seven publicly available models (AFTOX, DEGADIS, HEGADAS, HGSYSTEM, INPUFF, OB/DG and SLAB), six proprietary models (AIRTOX, CHARM, FOCUS, GASTAR, PHAST and TRACE), and two "benchmark" analytical models (the Gaussian Plume Model and the analytical approximations to the Britter and McQuaid Workbook nomograms). The field data were divided into three groups—continuous dense gas releases (Burro LNG, Coyote LNG, Desert Tortoise NH 3-gas and aerosols, Goldfish HF-gas and aerosols, and Maplin Sands LNG), continuous passive gas releases (Prairie Grass and Hanford), and instantaneous dense gas releases (Thorney Island freon). The dense gas models that produced the most consistent predictions of plume centerline concentrations across the dense gas data sets are the Britter and McQuaid, CHARM, GASTAR, HEGADAS, HGSYSTEM, PHAST, SLAB and TRACE models, with relative mean biases of about ±30% or less and magnitudes of relative scatter that are about equal to the mean. The dense gas models tended to overpredict the plume widths and underpredict the plume depths by about a factor of two. All models except GASTAR, TRACE, and the area source version of DEGADIS perform fairly well with the continuous passive gas data sets. Some sensitivity studies were also carried out. It was found that three of the more widely used publicly-available dense gas models (DEGADIS, HGSYSTEM and SLAB) predicted increases in concentration of about 70% as roughness length decreased by an order of magnitude for the Desert Tortoise and Goldfish field studies. It was also found that none of the dense gas models that were considered came close to simulating the observed factor of two increase in peak concentrations as averaging time decreased from several minutes to 1 s. Because of their assumption that a concentrated dense gas core existed that was unaffected by variations in averaging time, the dense gas

  9. Is mudflow in Sidoarjo, East Java due to the pumping mechanism of hot air bubbles? : Laboratory simulations and field observations

    NASA Astrophysics Data System (ADS)

    Nurhandoko, Bagus Endar B.

    2015-09-01

    Extraordinary mudflow has happened in Sidoarjo, East Java, Indonesia since 2006. This mud comes from the giant crater that is located close to the BJP - 01. Thousands of homes have been submerged due to mudflow. Till today this giant mud crater is still has great strength despite the mud flowing over 8 years. This is a very rare phenomenon in the world. This mud flow mechanism raises big questions, because it has been going on for years, naturally the mudflow will stop by itself because the pressure should be reduced. This research evaluates all aspects of integrated observations, laboratory tests and field observations since the beginning of this ongoing mudflow. Laboratory tests were done by providing hot air bubbles into the fluid inside the inverted funnel showed that the fluid can flow with a high altitude. It is due to the mechanism of buoyant force from air bubbles to the water where the contrast density of the water and the air is quite large. Quantity of air bubbles provides direct effect to the debit of fluid flow. Direct observation in the field, in 2006 and 2007, with TIMNAS and LPPM ITB showed the large number of air bubbles on the surface of the mud craters. Temperature observation on the surface of mud crater is around 98 degree C whereas at greater depth shows the temperature is increasingly rising. This strengthens the hypothesis or proves that the mud pumping mechanism comes from buoyant force of hot air bubbles. Inversion gravity images show that the deep subsurface of main crater is close to volcanic layers or root of Arjuna mountain. Based on the simulation laboratory and field observation data, it can be concluded that the geothermal factor plays a key role in the mudflow mechanism.

  10. Parametric Study of Preferential Ion Heating Due to Intermittent Magnetic Fields in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Carbajal Gomez, L.; Chapman, S. C.; Dendy, R. O.; Watkins, N. W.

    2014-12-01

    In situ observations and remote measurements of the solar wind show strong preferential heating of ions along the ambient magnetic field. Understanding the mechanism for this heating process is an open problem. The observed broad-band spectrum of Alfven waves permeating the fast solar wind provide a candidate mechanism for this preferential heating through wave-particle interactions on ion kinetic scales. Previous analytical and numerical studies have considered a single pump wave [1, 2] or a turbulent, broad-band spectra of Alfven waves [3, 4, 5] to drive the ion heating. The latter studies investigated the effects on ion heating due to different initial 1/fγpower spectral exponents and number of modes and the signals were random phase. However, the observed solar wind fluctuations are intermittent so that the phases of the modes comprising the power spectrum are not random. Non-Gaussian fluctuations are seen both on scales identified with the inertial range of Alfvenic turbulence [6], and on longer scales typified by '1/f' spectra [7]. We present results of the first parametric numerical simulations on the effects of different levels of intermittency of the broad-band spectra of Alfven waves on the preferential heating of ions in the solar wind. We performed hybrid simulations for the local heating of the solar wind, which resolves the full kinetic physics of the ions and treats the electrons as a charge-neutralizing fluid. Our simulations evolve the full vector velocities and electromagnetic fields in one configuration space coordinate and in time.We compare the efficiency of different levels of intermittency of the initial turbulent fields and their effect on the efficiency of the wave-particle interactions which are a mechanism for driving preferential ion heating in the solar wind. [1] J. A. Araneda, E. Marsh, A. F. Viñas, J. Geophys. Res. 112, A04104 (2007). [2] J. A. Araneda, E. Marsh, A. F. Viñas, Phys. Rev. Lett. 100, 125003 (2008) [3] Y. G. Maneva, A

  11. Relaxation of virtual cathode oscillations due to transverse effects in a crossed-field diode

    SciTech Connect

    Cartwright, K.L.; Verboncoeur, J.P.; Gopinath, V.P.; Birdsall, C.K.

    1996-12-31

    Recent studies of cylindrical and planar cross-field diodes indicate the transverse dimension plays a role in delaying the onset of virtual cathode oscillations for currents injected above the theoretical limiting current. For 1d and 2d planar devices, the limiting current for the magnetized and unmagnetized diodes is examined for cold and thermal injection. A significant difference between the 1d and 2d smooth diodes is that the transverse direction gives an extra degree of freedom which is found to warm the electrons rapidly. The mechanism of this warming appears to be an instability in the transverse direction. The simulations show three different states; laminar flow, virtual cathode oscillation and warm flow. Warm flow occurs when the electron has a spread of energy, either due to an instability or by thermal injection, when they pas through the potential minimum. Birdsall and Bridges showed that a small thermal spread of injected electrons damps virtual cathode oscillations. This warming effect allows warm flow to exist on the 2d state diagram which is not found on the 1d state diagram for cold emission. Parameter space is explored on these state diagrams for B = 0 and B = B{sub Hull} for J near state transitions (J {approx_equal} J{sub C}).

  12. Modeling surface deformation due to CO2 injection at an enhanced oil recovery field in Texas

    NASA Astrophysics Data System (ADS)

    Yang, Q.; Abdollahzadeh, M.; Dixon, T. H.; Malservisi, R.; Hosseini, S.

    2013-12-01

    The Geodesy Laboratory at the University of South Florida has operated 3 C-GPS stations at an enhanced oil recovery field in Texas since October 2011. Our GPS sites recorded vertical uplift during the injection phase when the reservoir was initially pressurized, and localized subsidence in phase with reservoir pressure after oil extraction started. In this study, we use analytical and numerical models to better understand the small-scale surface deformation observed by GPS due to CO2 injection. First, we use an analytical model of a pressurized horizontal circular crack in an elastic half-space to fit the surface deformation data. Then, constrained by the analytical modeling results, we develop a poroelastic Finite Element Model (FEM) to investigate the influence of reservoir geometry and overlying stratigraphy on surface displacement. A sensitivity study is carried out to understand the effects of realistic geometry and material properties on surface deformation. Our preliminary results show that a poroelastic FEM can explain the location-dependant time delay between the injection and surface response.

  13. Field evaluations of marine oil spill bioremediation.

    PubMed Central

    Swannell, R P; Lee, K; McDonagh, M

    1996-01-01

    Bioremediation is defined as the act of adding or improving the availability of materials (e.g., nutrients, microorganisms, or oxygen) to contaminated environments to cause an acceleration of natural biodegradative processes. The results of field experiments and trials following actual spill incidents have been reviewed to evaluate the feasibility of this approach as a treatment for oil contamination in the marine environment. The ubiquity of oil-degrading microorganisms in the marine environment is well established, and research has demonstrated the capability of the indigenous microflora to degrade many components of petroleum shortly after exposure. Studies have identified numerous factors which affect the natural biodegradation rates of oil, such as the origin and concentration of oil, the availability of oil-degrading microorganisms, nutrient concentrations, oxygen levels, climatic conditions, and sediment characteristics. Bioremediation strategies based on the application of fertilizers have been shown to stimulate the biodegradation rates of oil in aerobic intertidal sediments such as sand and cobble. The ratio of oil loading to nitrogen concentration within the interstitial water has been identified to be the principal controlling factor influencing the success of this bioremediation strategy. However, the need for the seeding of natural environments with hydrocarbon-degrading bacteria has not been clearly demonstrated under natural environmental conditions. It is suggested that bioremediation should now take its place among the many techniques available for the treatment of oil spills, although there is still a clear need to set operational limits for its use. On the basis of the available evidence, we have proposed preliminary operational guidelines for bioremediation on shoreline environments. PMID:8801437

  14. Field evaluations of marine oil spill bioremediation.

    PubMed

    Swannell, R P; Lee, K; McDonagh, M

    1996-06-01

    Bioremediation is defined as the act of adding or improving the availability of materials (e.g., nutrients, microorganisms, or oxygen) to contaminated environments to cause an acceleration of natural biodegradative processes. The results of field experiments and trials following actual spill incidents have been reviewed to evaluate the feasibility of this approach as a treatment for oil contamination in the marine environment. The ubiquity of oil-degrading microorganisms in the marine environment is well established, and research has demonstrated the capability of the indigenous microflora to degrade many components of petroleum shortly after exposure. Studies have identified numerous factors which affect the natural biodegradation rates of oil, such as the origin and concentration of oil, the availability of oil-degrading microorganisms, nutrient concentrations, oxygen levels, climatic conditions, and sediment characteristics. Bioremediation strategies based on the application of fertilizers have been shown to stimulate the biodegradation rates of oil in aerobic intertidal sediments such as sand and cobble. The ratio of oil loading to nitrogen concentration within the interstitial water has been identified to be the principal controlling factor influencing the success of this bioremediation strategy. However, the need for the seeding of natural environments with hydrocarbon-degrading bacteria has not been clearly demonstrated under natural environmental conditions. It is suggested that bioremediation should now take its place among the many techniques available for the treatment of oil spills, although there is still a clear need to set operational limits for its use. On the basis of the available evidence, we have proposed preliminary operational guidelines for bioremediation on shoreline environments. PMID:8801437

  15. Evaluation Field Building in South Asia: Reflections, Anecdotes, and Questions

    ERIC Educational Resources Information Center

    Hay, Katherine

    2010-01-01

    This article examines evaluation field building in South Asia and the role of international collaboration in this field building. The article explores aspects of the supply and demand of development evaluation and the political, historical, and systemic factors that bridge or block evaluation use. The article calls for and suggests elements to…

  16. Compression and Cavitation of Externally Applied Magnetic Field on a Hohlraum due to Non-Local Heat Flow Effects

    NASA Astrophysics Data System (ADS)

    Joglekar, Archis; Thomas, Alec; Ridgers, Chris; Kingham, Rob

    2015-11-01

    In this study, we present full-scale 2D kinetic modeling of externally imposed magnetic fields on hohlraums with laser heating. We observe magnetic field cavitation and compression due to thermal energy transport. Self-consistent modeling of the electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's Law. A complete Ohm's Law contains magnetic field advection through the Nernst mechanism that arises due to the heat flow. Magnetic field amplification by a factor of 3 occurs due to magnetic flux pile-up from Nernst convection. The magnetic field cavitates towards the hohlraum axis over a 0.5 ns time scale due to Nernst convection. This results in significantly different magnetic field profiles and slower cavitation than can be expected due to the plasma bulk flow. Non-local electrons contribute to the heat flow down the density gradient resulting in an augmented Nernst convection mechanism that is included self-consistently through kinetic modeling. In addition to showing the prevalence of non-local heat flows, we show effects such as anomalous heat flow up the density gradient induced by inverse bremsstrahlung heating. This research was supported by the DOE through Grant No. DE SC0010621 and in part through computational resources and services provided by Advanced Research Computing at the University of Michigan, Ann Arbor.

  17. Evaluation of military field-water quality

    SciTech Connect

    Daniels, J.I.; Anspaugh, L.R.; Layton, D.W.

    1990-01-01

    The purpose of this report is to develop drinking-water standards for field water for selected threat agents of concern, including radioactivity. The threat agents of concern in addition to radioactivity are the classical chemical-warfare compounds hydrogen cyanide, organophosphorus nerve agents, and lewisite, as well as a fungal metabolite identified only recently as a possible threat agent, the trichothecene mycotoxin. The recommended standards are applicable only to military personnel deployed in the field, and they are meant to protect against performance-degrading effects resulting from the ingestion of the substances in field water. 25 refs., 11 figs., 19 tabs.

  18. Inner Core Anisotropy Due to the Magnetic Field--induced Preferred Orientation of Iron.

    PubMed

    Karato, S

    1993-12-10

    Anisotropy of the inner core of the Earth is proposed to result from the lattice preferred orientation of anisotropic iron crystals during their solidification in the presence of a magnetic field. The resultant seismic anisotropy is related to the geometry of the magnetic field in the core. This hypothesis implies that the observed anisotropy (fast velocity along the rotation axis) indicates a strong toroidal field in the core, which supports a strong field model for the geodynamo if the inner core is made of hexagonal close-packed iron. PMID:17781788

  19. Primary beam steering due to field leakage from superconducting SHMS magnets

    SciTech Connect

    Moore, Michael H.; Waidyawansa, Buddhini P.; Covrig, Silviu; Carlini, Roger; Benesch, Jay

    2014-11-05

    In this study, simulations of the magnetic fields from the Super High Momentum Spectrometer in Hall C at Thomas Jefferson National Accelerator Facility show significant field leakage into the region of the primary beam line between the target and the beam dump. Without mitigation, these remnant fields will steer the unscattered beam enough to limit beam operations at small scattering angles. Presented here are magnetic field simulations of the spectrometer magnets and a solution using optimal placement of a minimal amount of shielding iron around the beam line.

  20. Primary beam steering due to field leakage from superconducting SHMS magnets

    NASA Astrophysics Data System (ADS)

    Moore, M. H.; Waidyawansa, B. P.; Covrig, S.; Carlini, R.; Benesch, J.

    2014-11-01

    Simulations of the magnetic fields from the Super High Momentum Spectrometer in Hall C at Thomas Jefferson National Accelerator Facility show significant field leakage into the region of the primary beam line between the target and the beam dump. Without mitigation, these remnant fields will steer the unscattered beam enough to limit beam operations at small scattering angles. Presented here are magnetic field simulations of the spectrometer magnets and a solution using optimal placement of a minimal amount of shielding iron around the beam line.

  1. Electomagnetic field due to a non-axisymmetric current loop around Kerr blackhole

    NASA Astrophysics Data System (ADS)

    Pandey, U. S.; Dubey, G. S.

    1983-12-01

    The authors derive expressions for the electromagnetic field of a non-axisymmetric current loop around a Kerr blackhole. Complete solution for the "inside" as well as the "outside" regions of the current loop are determined using vacuum solutions of King (1977). A particular solution, the electromagnetic field of an equatorial current loop, is explicitly derived.

  2. Flute stabilization due to ponderomotive force created by an rf field with a variable gradient

    SciTech Connect

    Yasaka, Y.; Itatani, R.

    1986-06-30

    An rf-stabilization experiment was performed in the axisymmetric single-mirror device HIEI by controlling the radial-gradient scale length of the rf field with the aid of an azimuthally phased antenna array. The flute stability depends sensitively on the scale length of the perpendicular rf electric field, which shows that rf stabilization is caused by the ponderomotive force for ions.

  3. Field Evaluation of Low-E Storm Windows

    SciTech Connect

    Drumheller, S. Craig; Kohler, Christian; Minen, Stefanie

    2007-07-11

    A field evaluation comparing the performance of low emittance (low-e) storm windows with both standard clear storm windows and no storm windows was performed in a cold climate. Six homes with single-pane windows were monitored over the period of one heating season. The homes were monitored with no storm windows and with new storm windows. The storm windows installed on four of the six homes included a hard coat, pyrolitic, low-e coating while the storm windows for the other two homeshad traditional clear glass. Overall heating load reduction due to the storm windows was 13percent with the clear glass and 21percent with the low-e windows. Simple paybacks for the addition of the storm windows were 10 years for the clear glass and 4.5 years forthe low-e storm windows.

  4. Heating in the MRI environment due to superparamagnetic fluid suspensions in a rotating magnetic field

    NASA Astrophysics Data System (ADS)

    Cantillon-Murphy, P.; Wald, L. L.; Adalsteinsson, E.; Zahn, M.

    2010-03-01

    In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle's time constant, τ. As the magnetic field frequency is increased, the nanoparticle's magnetic moment lags the applied magnetic field at a constant angle for a given frequency, Ω, in rad/s. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid's temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4 and 7 degree Centigrade above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid's temperature in the MRI environment which is characterized by a large DC field, B0. Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B0. Results are presented for the expected temperature increase in small tumors (approximately 1 cm radius) over an appropriate range of magnetic fluid concentrations (0.002-0.01 solid volume fraction) and nanoparticle radii (1-10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful selection of the rotating or sinusoidal field parameters (field frequency and amplitude). The work indicates that it may be feasible to combine low-field MRI with a magnetic hyperthermia system using superparamagnetic iron oxide nanoparticles.

  5. Heating in the MRI environment due to superparamagnetic fluid suspensions in a rotating magnetic field

    PubMed Central

    Wald, L.L.; Adalsteinsson, E.; Zahn, M.

    2009-01-01

    In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle’s time constant, τ. As the magnetic field frequency is increased, the nanoparticle’s magnetic moment lags the applied magnetic field at a constant angle for a given frequency, Ω, in rad/s. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid’s temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4°C and 7°C above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid’s temperature in the MRI environment which is characterized by a large DC field, B0. Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B0. Results are presented for the expected temperature increase in small tumors (~1 cm radius) over an appropriate range of magnetic fluid concentrations (0.002 to 0.01 solid volume fraction) and nanoparticle radii (1 to 10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful selection of the rotating or sinusoidal field parameters (field frequency and amplitude). The work indicates that it may be feasible to combine low-field MRI with a magnetic hyperthermia system using superparamagnetic iron oxide nanoparticles. PMID:20161608

  6. Transient electric field at high altitudes due to lightning: Possible role of induction field in the formation of elves

    NASA Astrophysics Data System (ADS)

    Lu, Gaopeng

    2006-01-01

    Space and time behaviors of electric field perturbation vector at high altitudes driven by lightning return stroke are examined in terms of its three individual components (i.e., electrostatic, induction, and radiation) with transmission line model, by specifying the current form in a return stroke channel, which is presumed to be vertically oriented. The result shows that at 90 km altitude, the induction E-field dominates in a small region with a radius of ˜11 km (depending on the speed of return stroke) directly above the lightning region, with a magnitude comparable to radiation field and a relatively longer timescale. We conclude that in addition to the radiation field considered in previous theoretical modeling, the induction component in lightning E-field is likely one new energy source for the creation of elves. This might be able to explain the observed pancake shape of some elves with a luminous central part, while the more complete modeling including the formation mechanism of elves is required.

  7. Fresh and evolutionary-type field-aligned irregularities generated near sunrise terminator due to overshielding electric fields

    NASA Astrophysics Data System (ADS)

    Tulasi Ram, S.; Ajith, K. K.; Yamamoto, M.; Otsuka, Y.; Yokoyama, T.; Niranjan, K.; Gurubaran, S.

    2015-07-01

    The unusual evolution of fresh and intense field-aligned irregularities (FAI) near sunrise terminator which further sustained for more than 90 min of postsunrise period was observed by Equatorial Atmosphere Radar at Kototabang during a minor geomagnetic storm period. These FAI echoes were initially observed around 250-350 km altitudes, growing upward under eastward polarization electric fields indicating the plasma bubbles that are fully depleted along the flux tube. The background low-latitude F layer dynamics that lead to the development of these dawn time FAI have been investigated from two ionosondes at near magnetic conjugate low-latitude locations. A minor geomagnetic storm was in progress which did not appear to cause any large electric field perturbations at preceding postsunset to midnight period over Indonesian sector. However, the prompt penetration of overshielding electric fields associated with sudden northward turning of interplanetary magnetic field Bz caused spectacular ascent of F layer and development of fresh, intense, and upward evolutionary plasma bubbles near sunrise terminator.

  8. Kilotesla Magnetic Field due to a Capacitor-Coil Target Driven by High Power Laser

    PubMed Central

    Fujioka, Shinsuke; Zhang, Zhe; Ishihara, Kazuhiro; Shigemori, Keisuke; Hironaka, Youichiro; Johzaki, Tomoyuki; Sunahara, Atsushi; Yamamoto, Naoji; Nakashima, Hideki; Watanabe, Tsuguhiro; Shiraga, Hiroyuki; Nishimura, Hiroaki; Azechi, Hiroshi

    2013-01-01

    Laboratory generation of strong magnetic fields opens new frontiers in plasma and beam physics, astro- and solar-physics, materials science, and atomic and molecular physics. Although kilotesla magnetic fields have already been produced by magnetic flux compression using an imploding metal tube or plasma shell, accessibility at multiple points and better controlled shapes of the field are desirable. Here we have generated kilotesla magnetic fields using a capacitor-coil target, in which two nickel disks are connected by a U-turn coil. A magnetic flux density of 1.5 kT was measured using the Faraday effect 650 μm away from the coil, when the capacitor was driven by two beams from the GEKKO-XII laser (at 1 kJ (total), 1.3 ns, 0.53 or 1 μm, and 5 × 1016 W/cm2). PMID:23378905

  9. Primary Beam Steering Due To Field Leakage From Superconducting SHMS Magnets

    NASA Astrophysics Data System (ADS)

    Moore, Michael; Covrig, Silviu; Carlini, Roger; Waidyawansa, Buddhini; Benesch, Jay

    2014-03-01

    The Super High Momentum Spectrometer (SHMS) was designed for the 12 GeV/c physics program in Hall C at Thomas Jefferson National Accelerator (JLab). At JLab an electron beam impinges on a fixed target and scattered particles are analyzed with magnetic spectrometers. The SHMS angular acceptance is 5 .5° <= θ <=40° . When positioned at θ = 5 .5° and full field strength the external fields from the magnets are large enough to steer the unscattered primary beam away from the beam dump window located 51.8 m from the target. The effects of these magnetic fields on the primary beam line downstream of the target are studied using Opera 3-D and TOSCA. A solution is presented that uses passive elements to shape these fields and assure that the primary beam is steered onto the beam dump window.

  10. Computation of induced electric field and temperature elevation in human due to lightning current

    NASA Astrophysics Data System (ADS)

    Nagai, T.; Hirata, A.

    2010-05-01

    The present study investigated induced electric field and temperature elevation in specific tissues/organs of an anatomically based human body model for the lightning current. The threshold amplitude of the current inducing ventricular fibrillation and skin burning are estimated from computed induced electric field and temperature elevation with formulas for electrical stimulation and thermal damage. The computational results obtained herein were reasonably consistent with clinical observation.

  11. Alignment of Iron Nanoparticles in a Magnetic Field Due to Shape Anisotropy

    DOE PAGESBeta

    Radhakrishnan, Balasubramaniam; Nicholson, Don M; Eisenbach, Markus; Ludtka, Gerard Michael; Rios, Orlando; Parish, Chad M

    2015-07-09

    During high magnetic field processing there is evidence for alignment of non-spherical metallic particles above the Curie temperature in alloys with negligible magneto-crystalline anisotropy. The main driving force for alignment is the magnetic shape anisotropy. Current understanding of the phenomenon is not adequate to quantify the effect of particle size, aspect ratio, temperature and the magnetic field on particle alignment. We demonstrate a Monte Carlo approach coupled with size scaling to show the conditions under which alignment is possible.

  12. Simulations of magnetic field gradients due to micro-magnets on a triple quantum dot circuit

    NASA Astrophysics Data System (ADS)

    Poulin-Lamarre, G.; Bureau-Oxton, C.; Kam, A.; Zawadzki, P.; Studenikin, S.; Aers, G.; Pioro-Ladrière, M.; Sachrajda, A. S.

    2013-12-01

    To quantify the effects of local magnetic fields on triple quantum dots, the Heisenberg Hamiltonian has been diagonalized for three electrons coupled via the exchange interaction. In particular, we have investigated different geometries of micro-magnets located on top of the triple dot in order to optimize the field gradient characteristics. In this paper, we focus on two geometries which are candidates for an addressable EDSR triple quantum dot device.

  13. Simulations of magnetic field gradients due to micro-magnets on a triple quantum dot circuit

    SciTech Connect

    Poulin-Lamarre, G.; Bureau-Oxton, C.; Kam, A.; Zawadzki, P.; Aers, G.; Studenikin, S.; Pioro-Ladrière, M.; Sachrajda, A. S.

    2013-12-04

    To quantify the effects of local magnetic fields on triple quantum dots, the Heisenberg Hamiltonian has been diagonalized for three electrons coupled via the exchange interaction. In particular, we have investigated different geometries of micro-magnets located on top of the triple dot in order to optimize the field gradient characteristics. In this paper, we focus on two geometries which are candidates for an addressable EDSR triple quantum dot device.

  14. Field Evaluation of a General Purpose Simulator.

    ERIC Educational Resources Information Center

    Spangenberg, Ronald W.

    The use of a general purpose simulator (GPS) to teach Air Force technicians diagnostic and repair procedures for specialized aircraft radar systems is described. An EC II simulator manufactured by Educational Computer Corporation was adapted to resemble the actual configuration technicians would encounter in the field. Data acquired in the…

  15. Phase shifts in precision atom interferometry due to the localization of atoms and optical fields

    SciTech Connect

    Wicht, A.; Sarajlic, E.; Hensley, J.M.; Chu, S.

    2005-08-15

    We discuss details of momentum transfer in the interaction between localized atoms and localized optical fields which are relevant to precision atom interferometry. Specifically, we consider a {lambda}-type atom coherently driven between its ground states by a bichromatic optical field. We assume that the excited state can be eliminated adiabatically from the time evolution. It is shown that the average recoil momentum is given by the phase gradient of the two-photon field at the 'position' of the atom, provided that the optical field can be described by a function which is separable in position and time and that the atomic wave function is symmetric and well localized within the optical field envelope. The result does not require the optical fields to have a Gaussian spatial dependence. Our discussion provides the basis for the analysis of systematic errors in precision atom interferometry arising from optical wave-front curvature, wave-front distortion, and the Gouy phase shift of Gaussian beams. We apply our result to the atom interferometer experiment of Chu and co-workers which measures the fine-structure constant.

  16. Evaluation of Transcutaneous Electrical Nerve Stimulation as a Treatment of Neck Pain due to Musculoskeletal Disorders

    PubMed Central

    Maayah, Mikhled; Al-Jarrah, Mohammed

    2010-01-01

    Background This study was designed to evaluate transcutaneous electrical nerve stimulation (TENS) as a treatment for neck pain due to musculoskeletal disorders within the context of a physiotherapy treatment. Methods Thirty subjects with neck pain were randomly allocated to two groups, treated with either TENS (n = 15) or placebo (n = 15). Each subject received one session for one hour. All subjects were evaluated before, during treatment, after switch off and again a week after by using Myometer machine. All subjects completed the follow-up assessment. Subjects referred for out-subjects' physiotherapy department, fulfilling the inclusion and exclusion criteria, took part in the study. Results The assessments were compared and used to measure outcome treatment. Improvement in their condition was measured in terms of a reduction in the individual's level of pain during the week after the end of the first session. At the end of the first session, the study showed that 11 subjects (73%) in the treatment and 7 subjects (43%) in the control groups had gained marked improvement. These results are statistically highly significant, (P = 0.01) at the end of the follow-up assessment. Conclusions A conclusion could be drawn that a single intense TENS treatment is an effective treatment for neck pain due to musculoskeletal disorders. On the other hand, TENS showed an effective pain relief with subjects who have a mild neck pain rather than those with severe symptoms. Keywords Musculoskeletal disorders; Transcutaneous electrical nerve stimulation; Neck pain PMID:21629525

  17. Noise due to field- and current instabilities in CdS

    NASA Astrophysics Data System (ADS)

    Böer, Karl W.

    1999-04-01

    In this review paper, we summerize the field and current instabilities that occur when the conductivity decreases more than linearly with increasing field, or increases sufficient steeply with increased current density. In both cases well defined transition ranges exist that causes a chaotic development of field-or current-inhomogeneities, respectively. These are the ranges in which substantial additional low-frequency electronic noise is generated that shows a typical 1/f behavior. Field instabilities occur in a range of an N-shaped current-voltage characteristic that result in high-field domains which can be stationary or move through the device and cause a stationary or oscillating reduction in current. The latter, as the Gunn effect, enjoys technical application as an ac generator. In CdS the negative differential conductivity regime is trap-controlled and thereby kinetic effects are slowed down so that they can be observed visually, using the Franz-Keldysh effect. During such observation, chaotic effects can be seen before the periodic oscillations are organized, and cause a substantial increase in low-frequency noise. The chaotic initiation of well organized periodically moving high-field domains are discussed in a phase-portrait analysis of the nonlinear dynamics for pattern formation in semiconductor devices. Also in an S-shaped characteristic that is initiated by substantial Joule's heating and yields current channel formation, current instabilities can occur that lead to low frequency noise. The related phenomena are briefly summerized in this review. The experimental evidence of these chaotic developments of field- and current-instabilities is shown during the oral presentation in a movie, using electro-optical or electro-thermo-optical effects for visualization.

  18. Evaluating 6 ricin field detection assays.

    PubMed

    Slotved, Hans-Christian; Sparding, Nadja; Tanassi, Julia Tanas; Steenhard, Nina R; Heegaard, Niels H H

    2014-01-01

    This study presents data showing the performance of 6 commercial detection assays against ricin around concentrations specified as detection limits by the producers. A 2-fold dilution series of 20 ng/ml ricin was prepared and used for testing the lateral-flow kits: BADD, Pro Strips™, ENVI, RAID DX, Ricin BioThreat Alert, and IMASS™ device. Three of the 6 tested field assays (IMASS™ device, ENVI assay, and the BioThreat Alert assay) were able to detect ricin, although differences in the measured detection limits compared to the official detection limits and false-negative results were observed. We were not able to get the BADD, Pro Strips™, and RAID assays to function in our laboratory. We conclude that when purchasing a field responder assay, there is large variation in the specificity of the assays, and a number of in-house tests must be performed to ensure functionality. PMID:24978020

  19. Condensing Hybrid Water Heater Monitoring Field Evaluation

    SciTech Connect

    Maguire, J.; Earle, L.; Booten, C.; Hancock, C. E.

    2011-10-01

    This paper summarizes the Mascot home, an abandoned property that was extensively renovated. Several efficiency upgrades were integrated into this home, of particular interest, a unique water heater (a Navien CR240-A). Field monitoring was performed to determine the in-use efficiency of the hybrid condensing water heater. The results were compared to the unit's rated efficiency. This unit is Energy Star qualified and one of the most efficient gas water heaters currently available on the market.

  20. Effect of Combined Loading Due to Bending and Internal Pressure on Pipe Flaw Evaluation Criteria

    NASA Astrophysics Data System (ADS)

    Miura, Naoki; Sakai, Shinsuke

    Considering a rule for the rationalization of maintenance of Light Water Reactor piping, reliable flaw evaluation criteria are essential for determining how a detected flaw will be detrimental to continuous plant operation. Ductile fracture is one of the dominant failure modes that must be considered for carbon steel piping and can be analyzed by elastic-plastic fracture mechanics. Some analytical efforts have provided various flaw evaluation criteria using load correction factors, such as the Z-factors in the JSME codes on fitness-for-service for nuclear power plants and the section XI of the ASME boiler and pressure vessel code. The present Z-factors were conventionally determined, taking conservativity and simplicity into account; however, the effect of internal pressure, which is an important factor under actual plant conditions, was not adequately considered. Recently, a J-estimation scheme, LBB.ENGC for the ductile fracture analysis of circumferentially through-wall-cracked pipes subjected to combined loading was developed for more accurate prediction under more realistic conditions. This method explicitly incorporates the contributions of both bending and tension due to internal pressure by means of a scheme that is compatible with an arbitrary combined-loading history. In this study, the effect of internal pressure on the flaw evaluation criteria was investigated using the new J-estimation scheme. The Z-factor obtained in this study was compared with the presently used Z-factors, and the predictability of the current flaw evaluation criteria was quantitatively evaluated in consideration of the internal pressure.

  1. A platform to study magnetic field amplification of laser driven shocks due to induced turbulence

    NASA Astrophysics Data System (ADS)

    Meinecke, Jena; Doyle, Hugo; Bell, A. R.; Crowston, Robert; Drake, Paul; Fatenejad, M.; Hartley, Nick; Koenig, Michel; Kuramitsu, Y.; Kuranz, Carolyn; Lamb, Don; MacDonald, Mike; Miniati, F.; Murphy, Chris; Pelka, Alex; Ravasio, Alessandra; Reville, Brian; Sakawa, Y.; Schekochihin, A. A.; Scopatz, Anthony; Tzeferacos, Petros; Wan, Wesley; Woolsey, Nigel; Gregori, Gianluca

    2012-10-01

    Misaligned pressure and temperature gradients associated with asymmetrical shock waves generate currents which seed magnetic fields (Biermann battery process). These fields could then be further amplified by increasing particle gyration driven by vorticity and turbulence. Studies of such phenomena have been conducted at the Rutherford Appleton Laboratory and scaled to astrophysical conditions (e.g., protogalacitc structure formation) using magnetohydrodynamic scaling techniques. Shock waves were driven in a 1 mbar Argon gas filled chamber from ablation of 500 micron Carbon rods using 300 J of 527 nm, 1 ns pulse light. A plastic grid was positioned 1 cm from the target to drive turbulence with outer scale ˜1 mm (the size of the grid opening). An induction coil, located 2 cm from the grid, was used to measure the magnetic field while optical diagnostics were used to track the fluid flow. Preliminary results and comparisons with hydrodynamic codes will be shown.

  2. Formation of electric dipoles in pea stem tissue due to an electric field

    NASA Astrophysics Data System (ADS)

    Ahmadi, Fatemeh; Farahani, Elham

    2016-07-01

    For examining the effect of an electrical field (DC) on pea seed, we exposed the pea seeds to electric fields with intensities 1, 4 and 7 kV/cm for 30, 230, 430 and 630 seconds. The tests were repeated three times, and each iteration had 5 seeds. Then, the seeds were moved to packaged plates. Finally, microscopic observation of the pea stem tissue showed that the application of a DC electrical field caused a deformation in the pea stem tissue. The results led us to examine the deformation of the tissue theoretically and to address that deformation as an electrostatic problem. In this regard, we modeled the pea stem based on the formation of electric dipoles. Then, theoretically, we calculated the force acting on each xylem section by coding, and the results were consistent with the experimental data.

  3. Decrease of electron spin lifetime in external electric field due to intervalley phonon scattering in silicon

    NASA Astrophysics Data System (ADS)

    Qing, Lan; Dery, Hanan; Li, Jing; Appelbaum, Ian

    2012-02-01

    We derive a simple approximate expression of the spin lifetime of drifting electrons in silicon. This expression agrees well with elaborate Monte Carlo simulations of the charge transport and spin relaxation of conduction electrons heated by the electric field. Already at low temperatures, the drifting electrons become hot enough to undergo f-processes (scattering between valleys of different crystal axes following emission of a shortwave phonon). Such a process involves a direct coupling of valence and conduction bands and dominates the spin relaxation. A sharp decrease of spin lifetime can then be expected in intermediate electric fields in between ˜100 V/cm and ˜1 kV/cm. When electrons are transported between a spin injector and a spin-resolved detector, the decrease of both transit time and spin lifetime results in a non-monotonic behavior of the detected spin polarization with the electric field. The theory shows excellent agreement with empirical results.

  4. Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks

    SciTech Connect

    Hong, Qin; Guan, Xiaoyin; Fisch, Nathaniel J.

    2011-07-19

    In tokamaks, Ware pinch is a well known neoclassical effect for trapped particles in response to a toroidal electric field. It is generally believed that there exists no similar neoclassical effect for circulating particles without collisions. However, this belief is erroneous, and misses an important effect. We show both analytically and numerically that under the influence of a toroidal electric field parallel to the current, the circulating orbits drift outward toward the outer wall with a characteristic velocity O ({var_epsilon}{sup -1}) larger than the E x B velocity, where {var_epsilon} is the inverse aspect-ratio of a tokamak. During a RF overdrive, the toroidal electric field is anti-parallel to the current. As a consequence, all charged particles, including backward runaway electrons, will drift inward towards the inner wall.

  5. Magnetic Field Due to a Finite Length Current-Carrying Wire Using the Concept of Displacement Current

    ERIC Educational Resources Information Center

    Buschauer, Robert

    2014-01-01

    In undergraduate E&M courses the magnetic field due to a finite length, current-carrying wire can be calculated using the Biot-Savart law. However, to the author's knowledge, no textbook presents the calculation of this field using the Ampere-Maxwell law: ?B [multiplied by] dl = µ[subscript 0] (I + e[subscript 0] dF/dt) [multiplied by] 1

  6. SEISMIC PERFORMANCE OF RC BRIDGE COLUMNS UNDER VARYING AXIAL FORCE DUE TO NEAR-FIELD VERTICAL GROUND MOTIONS

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Hiroshi; Kumagai, Yuji; Kawashima, Kazuhiko

    Recently, high acceleration and high frequency near-field vertical ground motions were recorded at several sites. The extreme vertical ground motions can induce high frequency varying axial force which develop even tensile force in reinforced concrete bridge columns. Cyclic loading experiments of RC columns were conducted to clarify the seismic performance of RC bridge columns under near-field vertical ground motions. It is shown that core concrete is crushed extensively due to varying axial force after longitudinal bars buckle.

  7. Transient particle acceleration in strongly magnetized neutron stars. II - Effects due to a dipole field geometry

    NASA Technical Reports Server (NTRS)

    Fatuzzo, Marco; Melia, Fulvio

    1991-01-01

    Sheared Alfven waves generated by nonradial crustal disturbances above the polar cap of a strongly magnetized neutron star induce an electric field component parallel to B. An attempt is made to determine the manner in which the strong radial dependence of B affects the propagation of these sheared Alfven waves, and whether this MHD process is still an effective particle accelerator. It is found that although the general field equation is quite complicated, a simple wavelike solution can still be obtained under the conditions of interest for which the Alfven phase velocity decouples from the wave equation. The results may be applicable to gamma-ray burst sources.

  8. Poloidal electric field due to ICRH and its effect on neoclassical transport

    SciTech Connect

    Vacca, L. )

    1994-10-15

    We study the transport of a plasma in which a minority ion species is heated by fast Alfven waves. The strong anisotropy of the minority distribution function gives origin to a poloidal electric field. We calculate the poloidal dependence of the electric potential by numerically integrating the leading order minority distribution function. When the amplitude of this field is such that electrostatic trapping is not negligible in comparison to the magnetic trapping then neoclassical transport can be enhanced as found in previous work. The linearized kinetic equations are solved using a variational method in the banana regime. Approximate analytic expressions for the transport coefficients are given.

  9. Electro-elastic fields due to a point charge in a flexoelectric medium

    NASA Astrophysics Data System (ADS)

    Sharma, Rajdeep

    2015-10-01

    Flexoelectricity provides a two-way connection between strain gradients and polarization that is pronounced at the nanoscale for isotropic materials which cannot link electromechanically via piezoelectricity. In this paper, the general equations for an isotropic, flexoelectric material were formulated, with contributions from strain gradients included. The electromechanical fields associated with a point charge in an infinite medium were derived, and results for GaAs were obtained. Our formulation yields two electromechanical length-scales, instead of one obtained from previous theories, and enables us to capture local fields accurately. Results from this paper provide insight into the electro-mechanical behavior of materials with charged defects.

  10. Calculating the electromagnetic field on the earth due to an electrodynamic tethered system in the ionosphere

    NASA Technical Reports Server (NTRS)

    Estes, Robert D.

    1989-01-01

    A method is presented for calculating the electromagnetic wave field on the earth's surface associated with the operation of an electrodynamic tethered satellite system of constant or slowly varying current in the upper ionosphere. The wave field at the ionospheric boundary and on the earth's surface is obtained by numerical integration. The results suggest that the ionospheric waves do not propagate into the atmosphere and that the image of the Alfven wings from a steady-current tether should be greatly broadened on the earth's surface.

  11. Non-locality in quantum field theory due to general relativity

    NASA Astrophysics Data System (ADS)

    Calmet, Xavier; Croon, Djuna; Fritz, Christopher

    2015-12-01

    We show that general relativity coupled to a quantum field theory generically leads to non-local effects in the matter sector. These non-local effects can be described by non-local higher dimensional operators which remarkably have an approximate shift symmetry. When applied to inflationary models, our results imply that small non-Gaussianities are a generic feature of models based on general relativity coupled to matter fields. However, these effects are too small to be observable in the cosmic microwave background.

  12. Relativistic electron loss process by pitch angle scattering due to field curvature

    NASA Astrophysics Data System (ADS)

    Lee, J. J.; Parks, G. K.; Lee, E.; McCarthy, M. P.; Min, K.; Kim, H.; Park, J.; Hwang, J.

    2006-12-01

    Relativistic electron dropout (RED) events are characterized by fast electron flux decrease at the geostationary orbit. It is known that the main loss process is non adiabatic and more effective for the high energy particles. RED events generally start to occur at midnight sector and propagate to noon sector and are correlated with magnetic field stretching. We discuss this kind of event can be caused from pitch angle diffusion induced when the gyro radius of the electrons is comparable to the radius of curvature of the magnetic field and the magnetic moment is not conserved any more. While this process has been studied theoretically, the question is whether electron precipitation could be explained with this process for the real field configuration. This paper will show that this process can successfully explain the precipitation that occurred on June 14, 2004 observed by the low-altitude (680 km) polar orbiting Korean satellite, STSAT-1. In this precipitation event, the energy dispersion showed higher energy electron precipitation occurred at lower L values. This feature is a good indicator that precipitation was caused by the magnetic moment scattering in the geomagnetic tail. This interpretation is supported by the geosynchronous satellite GOES observations that showed significant magnetic field distortion occurred on the night side accompanying the electron flux depletion. Tsyganenko-01 model also shows the magnetic moment scattering could occur under the geomagnetic conditions existing at that time. We suggest the pitch angle scattering by field curvature violating the first adiabatic invariant as a possible candidate for loss mechanism of relativistic electrons in radiation belt.

  13. Evidence of stochastic diffusion across a cross-field sheath due to Kelvin-Helmholtz vortices

    SciTech Connect

    Parker, S.E.; Xu, X.Q.; Lichtenberg, A.J.; Birdsall, C.K. )

    1992-03-15

    We identify mechanisms for particle transport across a cross-field sheath. We present a study of {bold E}{times}{bold B} drift motion in a vortex in which the ion drifts are perturbed by their finite gyroradii and electron drifts are perturbed by one or more traveling waves. Large-scale vortices, which are the result of nonlinear saturation of the Kelvin-Helmholtz instability resulting from shear in the {bold E}{times}{bold B} drift velocity, have been observed in plasma simulations of the cross-field sheath (K. Theilhaber and C. K. Birdsall, Phys. Rev. Lett. 62, 772 (1989); Phys. Fluids B 1, 2241 (1989); 1, 2260 (1989)). Small-scale turbulence is also present, and ions and electrons are transported across the sheath. A vortex alone does not allow for the observed electron transport because the electron drift orbits simply circulate. On the other hand, the ion motion can be stochastic from resonant interaction between harmonics of the drift motion and the gyromotion, independent of the background turbulence. The fluctuations in the ion density would then give rise to a small-amplitude wave spectrum. The combined action of the vortex fields and traveling-wave fields on the electron motion can then lead to stochastic electron diffusion. We study these effects, showing that the values of vortex fields observed in the simulation are sufficient to lead to both ion and electron stochasticity. Furthermore, the rate of the resulting diffusion is sufficient to account for the diffusion observed in the simulation.

  14. Field Evaluation of an Online Foster Parent Training System

    ERIC Educational Resources Information Center

    Buzhardt, Jay; Heitzman-Powell, Linda

    2006-01-01

    The authors developed and evaluated an online foster parent training system designed specifically for low-bandwidth Internet connections and individuals with limited Internet/computer experience. After preliminary onsite evaluations, a 2-week field test was conducted to evaluate the following dimensions: foster parents' pre- to post-test scores on…

  15. Field-Based Concerns about Fourth-Generation Evaluation Theory.

    ERIC Educational Resources Information Center

    Lai, Morris K.

    Some aspects of fourth generation evaluation procedures that have been advocated by E. G. Guba and Y. S. Lincoln were examined empirically, with emphasis on areas where there have been discrepancies between theory and field-based experience. In fourth generation evaluation, the product of an evaluation is not a set of conclusions, recommendations,…

  16. Enhanced excitonic photoconductivity due to built-in internal electric field in TlGaSe{sub 2} layered semiconductor

    SciTech Connect

    Seyidov, MirHasan Yu. Suleymanov, Rauf A.; Şale, Yasin; Balaban, Ertan

    2014-12-07

    The strong enhancement, by several orders of magnitude, of the excitonic peak within the photoconductivity spectrum of TlGaSe{sub 2} semiconductor was observed. The samples were polarized in external dc electric field, which was applied prior to the measurements. Due to the accumulation of charges near the surface, an internal electric field was formed. Electron-hole pairs that were created after the absorption of light are fallen in and then separated by the built-in electric field, which prevents radiative recombination process.

  17. The effect of space charge fields due to finite length electron beams in the free-electron laser

    NASA Technical Reports Server (NTRS)

    Tang, C.-M.; Sprangle, P.; Freund, H.; Colson, W.

    1982-01-01

    The space charge electric field of a finite length electron beam in the free electron laser amplifier with a tapered wiggler is analyzed. In the free drift region between the accelerator and laser, expressions for the increase of energy spread due to the self field are presented. In the FEL interaction region, the general conditions on the importance of the self electric field in the equations of motion is obtained. A numerical example of the FEL experiment at 10.6 microns is given.

  18. Finding the Shadows: Local Variations in the Stress Field due to Large Magnitude Earthquakes

    NASA Astrophysics Data System (ADS)

    Latimer, C.; Tiampo, K.; Rundle, J.

    2009-05-01

    Stress shadows, regions of static stress decrease associated with large magnitude earthquake have typically been described through several characteristics or parameters such as location, duration, and size. These features can provide information about the physics of the earthquake itself, as static stress changes are dependent on the following parameters: the regional stress orientations, the coefficient of friction, as well as the depth of interest (King et al, 1994). Areas of stress decrease, associated with a decrease in the seismicity rate, while potentially stable in nature, have been difficult to identify in regions of high rates of background seismicity (Felzer and Brodsky, 2005; Hardebeck et al., 1998). In order to obtain information about these stress shadows, we can determine their characteristics by using the Pattern Informatics (PI) method (Tiampo et al., 2002; Tiampo et al., 2006). The PI method is an objective measure of seismicity rate changes that can be used to locate areas of increases and/or decreases relative to the regional background rate. The latter defines the stress shadows for the earthquake of interest, as seismicity rate changes and stress changes are related (Dieterich et al., 1992; Tiampo et al., 2006). Using the data from the PI method, we can invert for the parameters of the modeled half-space using a genetic algorithm inversion technique. Stress changes will be calculated using coulomb stress change theory (King et al., 1994) and the Coulomb 3 program is used as the forward model (Lin and Stein, 2004; Toda et al., 2005). Changes in the regional stress orientation (using PI results from before and after the earthquake) are of the greatest interest as it is the main factor controlling the pattern of the coulomb stress changes resulting from any given earthquake. Changes in the orientation can lead to conclusions about the local stress field around the earthquake and fault. The depth of interest and the coefficient of friction both

  19. Field evaluation of an electromagnetic current meter based vertical profiler

    NASA Astrophysics Data System (ADS)

    Hamblin, P. F.; Marmoush, Y. M. R.; Boyce, F. M.; Smith, A. A.

    1987-10-01

    A current profiler consisting of a vertical array of three electromagnetic current meters has been evaluated through an intercomparison of the three sensors, with reference to nearby current and wave data and by comparison to recent laboratory performance tests (Aubrey and Trowbridge, 1985). Mean flow estimates are too uncertain and variable to allow bottom boundary layer shear stress to be estimated by the conventional logarithmic law method. As well as unexplained sudden shifts in the mean speed response, the comparison with vector-averaged current meter data indicates possible long-term reduction in response due to fouling of the sensors by biological growth. The directional response was less sensitive to fouling effects. The oscillatory response on one occasion after field deployment for 17 days indicates a reduction in response from 41 to 45% at a period of oscillation of 3 s in a combined steady and oscillatory flow field. This study demonstrates that despite careful laboratory calibration, electromagnetic current meters are not at present suitable for quantitative study of dynamics of sediment resuspension in near-bottom shallow-water environments.

  20. Heat flux due to poloidal electric field in the banana regime

    SciTech Connect

    Taguchi, M. )

    1992-02-01

    The heat flux due to poloidally varying electrostatic potential is calculated in the banana regime. This electrostatic potential determined self-consistently from charge neutrality is shown to increase the electron heat flux by a factor {radical}{ital m}{sub {ital i}}/{ital m}{sub {ital e}} compared with that when this potential is neglected, where {ital m}{sub {ital e}} and {ital m}{sub {ital i}} are the masses of electron and ion, respectively.

  1. Time-convoluted hotspot temperature field on a metal skin due to sustained arc stroke heating

    NASA Astrophysics Data System (ADS)

    Lee, T. S.; Su, W. Y.

    A previously developed time-convoluted heat-conduction theory is applied to the case of a metal plate whose heat source is sustained over time. Integral formulas are formally derived, and their utilization in practical arc-heating work is examined. The results are compared with experimental ones from titanium and aluminum plates subjected to sustained heating due to step switch-on dc arc sources, and reasonable agreement is found.

  2. Modelling of 3D fields due to ferritic inserts and test blanket modules in toroidal geometry at ITER

    NASA Astrophysics Data System (ADS)

    Liu, Yueqiang; Äkäslompolo, Simppa; Cavinato, Mario; Koechl, Florian; Kurki-Suonio, Taina; Li, Li; Parail, Vassili; Saibene, Gabriella; Särkimäki, Konsta; Sipilä, Seppo; Varje, Jari

    2016-06-01

    Computations in toroidal geometry are systematically performed for the plasma response to 3D magnetic perturbations produced by ferritic inserts (FIs) and test blanket modules (TBMs) for four ITER plasma scenarios: the 15 MA baseline, the 12.5 MA hybrid, the 9 MA steady state, and the 7.5 MA half-field helium plasma. Due to the broad toroidal spectrum of the FI and TBM fields, the plasma response for all the n  =  1–6 field components are computed and compared. The plasma response is found to be weak for the high-n (n  >  4) components. The response is not globally sensitive to the toroidal plasma flow speed, as long as the latter is not reduced by an order of magnitude. This is essentially due to the strong screening effect occurring at a finite flow, as predicted for ITER plasmas. The ITER error field correction coils (EFCC) are used to compensate the n  =  1 field errors produced by FIs and TBMs for the baseline scenario for the purpose of avoiding mode locking. It is found that the middle row of the EFCC, with a suitable toroidal phase for the coil current, can provide the best correction of these field errors, according to various optimisation criteria. On the other hand, even without correction, it is predicted that these n  =  1 field errors will not cause substantial flow damping for the 15 MA baseline scenario.

  3. Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

    NASA Technical Reports Server (NTRS)

    Kessel, R. L.; Armstrong, T. P.; Nuber, R.; Bandle, J.

    1985-01-01

    Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail.

  4. Velocity-Space Diffusion Coefficients Due to Full-Wave ICRF Fields in Toroidal Geometry

    SciTech Connect

    Harvey, R.W.; Jaeger, F.; Berry, L.A.; Batchelor, D.B.; D'Azevedo, E.; Carter, M.D.; Ershov, N.M.; Smirnov, A.P.; Bonoli, P.; Wright, J.C.; Smithe, D.N.

    2005-09-26

    Jaeger et al. have calculated bounce-averaged QL diffusion coefficients from AORSA full-wave fields, based on non-Maxwellian distributions from CQL3D Fokker-Planck code. A zero banana-width approximation is employed. Complementing this calculation, a fully numerical calculation of ion velocity diffusion coefficients using the full-wave fields in numerical tokamak equilibria has been implemented to determine the finite orbit width effects. The un-approximated Lorentz equation of motion is integrated to obtain the change in velocity after one complete poloidal transit of the tokamak. Averaging velocity changes over initial starting gyro-phase and toroidal angle gives bounce-averaged diffusion coefficients. The coefficients from the full-wave and Lorentz orbit methods are compared for an ITER DT second harmonic tritium ICRF heating case: the diffusion coefficients are similar in magnitude but reveal substantial finite orbit effects.

  5. Ultrasonic propagation velocity in magnetic and magnetorheological fluids due to an external magnetic field.

    PubMed

    Bramantya, M A; Motozawa, M; Sawada, T

    2010-08-18

    Ultrasonic propagation velocity in a magnetic fluid (MF) and magnetorheological fluid (MRF) changes with the application of an external magnetic field. The formation of clustering structures inside the MF and MRF clearly has an influence on the ultrasonic propagation velocity. Therefore, we propose a qualitative analysis of these structures by measuring properties of ultrasonic propagation. Since MF and MRF are opaque, non-contact inspection using the ultrasonic technique can be very useful for analyzing the inner structures of MF and MRF. In this study, we measured ultrasonic propagation velocity in a hydrocarbon-based MF and MRF precisely. Based on these results, the clustering structures of these fluids are analyzed experimentally in terms of elapsed time dependence and the effect of external magnetic field strength. The results reveal hysteresis and anisotropy in the ultrasonic propagation velocity. We also discuss differences of ultrasonic propagation velocity between MF and MRF. PMID:21386478

  6. Superdiffusion of two-dimensional Yukawa liquids due to a perpendicular magnetic field.

    PubMed

    Feng, Yan; Goree, J; Liu, Bin; Intrator, T P; Murillo, M S

    2014-07-01

    Stochastic transport of a two-dimensional (2D) dusty plasma liquid with a perpendicular magnetic field is studied. Superdiffusion is found to occur especially at higher magnetic fields with β of order unity. Here, β = ω(c)/ω(pd) is the ratio of the cyclotron and plasma frequencies for dust particles. The mean-square displacement MSD = 4D(α)t(α) is found to have an exponent α > 1, indicating superdiffusion, with α increasing monotonically to 1.1 as β increases to unity. The 2D Langevin molecular dynamics simulation used here also reveals that another indicator of random particle motion, the velocity autocorrelation function, has a dominant peak frequency ω(peak) that empirically obeys ω(peak)(2) = ω(c)(2) + ω(pd)(2)/4. PMID:25122399

  7. Spinmotive force due to motion of magnetic bubble arrays driven by magnetic field gradient

    PubMed Central

    Yamane, Yuta; Hemmatiyan, Shayan; Ieda, Jun'ichi; Maekawa, Sadamichi; Sinova, Jairo

    2014-01-01

    Interaction between local magnetization and conduction electrons is responsible for a variety of phenomena in magnetic materials. It has been recently shown that spin current and associated electric voltage can be induced by magnetization that depends on both time and space. This effect, called spinmotive force, provides for a powerful tool for exploring the dynamics and the nature of magnetic textures, as well as a new source for electromotive force. Here we theoretically demonstrate the generation of electric voltages in magnetic bubble array systems subjected to a magnetic field gradient. It is shown by deriving expressions for the electric voltages that the present system offers a direct measure of phenomenological parameter β that describes non-adiabaticity in the current induced magnetization dynamics. This spinmotive force opens a door for new types of spintronic devices that exploit the field-gradient. PMID:25365971

  8. Flow and acoustic field due to an inclined plate with a downstream splitter

    NASA Technical Reports Server (NTRS)

    Kim, C. M.; Conlisk, A. T.

    1993-01-01

    In the present work, the high Reynolds number flow past an inclined plate with a splitter plate placed in its wake is considered numerically. A numerical conformal mapping technique is employed to transform the two-plate system into the same number of cylinders: the flow field is assumed to be two-dimensional. The vortex shedding from the inclined plate is modelled using the discrete vortex method. It is shown that the splitter plate has a profound effect on the development of the flow over a range of values of a suitably defined offset parameter and for a range of positions of the leading edge of the splitter plate. The acoustic field is also calculated and the spectrum reflects the flow results.

  9. Alignment of iron nanoparticles in a magnetic field due to shape anisotropy

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, B.; Nicholson, D. M.; Eisenbach, M.; Parish, C.; Ludtka, G. M.; Rios, O.

    2015-11-01

    During high magnetic field solidification processing there is evidence for the alignment of nanoscale metallic particles with elongated morphologies that nucleate from a liquid metal. Such alignment occurs well above the Curie temperature of the particle where the magneto-crystalline anisotropy energy and exchange energy contributions are negligible. The main driving force for alignment is the magnetic shape anisotropy. Current understanding of the phenomenon is not adequate to quantify the effect of particle size, aspect ratio, temperature and the magnetic field on particle alignment. We demonstrate a Monte Carlo approach coupled with a scaling law for the dipole-dipole interaction energy as a function of the particle size to identify the conditions under which such alignment is possible.

  10. New experimental method of visualizing the electric field due to surface charges on circuit elements

    NASA Astrophysics Data System (ADS)

    Jacobs, Rebecca; de Salazar, Alex; Nassar, Antonio

    2010-12-01

    Although static surface charges on circuit elements are of enormous interest, recent papers and textbooks have only discussed the problem theoretically using analytical or numerical approaches. The only well-known experimental method to visualize the structure of electric fields around circuit elements was reported by Jefimenko almost half a century ago. In our paper, we report on a simple method to visualize the electric field produced by static surface charges on current-carrying circuit elements. Our method uses a mixture of PTFE (Teflon) sealant and mineral oil, a copper wire placed in the mixture's container, and two 6 kV power supplies. We believe that our new method can be used directly in the classroom.

  11. VISCOUS EVOLUTION AND PHOTOEVAPORATION OF CIRCUMSTELLAR DISKS DUE TO EXTERNAL FAR ULTRAVIOLET RADIATION FIELDS

    SciTech Connect

    Anderson, Kassandra R.; Adams, Fred C.; Calvet, Nuria

    2013-09-01

    This paper explores the effects of FUV radiation fields from external stars on circumstellar disk evolution. Disks residing in young clusters can be exposed to extreme levels of FUV flux from nearby OB stars, and observations show that disks in such environments are being actively photoevaporated. Typical FUV flux levels can be factors of {approx}10{sup 2}-10{sup 4} higher than the interstellar value. These fields are effective in driving mass loss from circumstellar disks because they act at large radial distance from the host star, i.e., where most of the disk mass is located, and where the gravitational potential well is shallow. We combine viscous evolution (an {alpha}-disk model) with an existing FUV photoevaporation model to derive constraints on disk lifetimes, and to determine disk properties as functions of time, including mass-loss rates, disk masses, and radii. We also consider the effects of X-ray photoevaporation from the host star using an existing model, and show that for disks around solar-mass stars, externally generated FUV fields are often the dominant mechanism in depleting disk material. For sufficiently large viscosities, FUV fields can efficiently photoevaporate disks over the entire range of parameter space. Disks with viscosity parameter {alpha} = 10{sup -3} are effectively dispersed within 1-3 Myr; for higher viscosities ({alpha} = 10{sup -2}) disks are dispersed within {approx}0.25-0.5 Myr. Furthermore, disk radii are truncated to less than {approx}100 AU, which can possibly affect the formation of planets. Our model predictions are consistent with the range of observed masses and radii of proplyds in the Orion Nebula Cluster.

  12. False vacuum bubble nucleation due to a nonminimally coupled scalar field

    SciTech Connect

    Lee, Wonwoo; Park, Chanyong; Lee, Bum-Hoon; Lee, Chul H.

    2006-12-15

    We study the possibility of forming the false vacuum bubble nucleated within the true vacuum background via the true-to-false vacuum phase transition in curved spacetime. We consider a semiclassical Euclidean bubble in the Einstein theory of gravity with a nonminimally coupled scalar field. In this paper we present the numerical computations as well as the approximate analytical computations. We mention the evolution of the false vacuum bubble after nucleation.

  13. False vacuum bubble nucleation due to a nonminimally coupled scalar field

    NASA Astrophysics Data System (ADS)

    Lee, Wonwoo; Lee, Bum-Hoon; Lee, Chul H.; Park, Chanyong

    2006-12-01

    We study the possibility of forming the false vacuum bubble nucleated within the true vacuum background via the true-to-false vacuum phase transition in curved spacetime. We consider a semiclassical Euclidean bubble in the Einstein theory of gravity with a nonminimally coupled scalar field. In this paper we present the numerical computations as well as the approximate analytical computations. We mention the evolution of the false vacuum bubble after nucleation.

  14. Undulation instability in a bilayer lipid membrane due to electric field interaction with lipid dipoles

    NASA Astrophysics Data System (ADS)

    Bingham, Richard J.; Olmsted, Peter D.; Smye, Stephen W.

    2010-05-01

    Bilayer lipid membranes (BLMs) are an essential component of all biological systems, forming a functional barrier for cells and organelles from the surrounding environment. The lipid molecules that form membranes contain both permanent and induced dipoles, and an electric field can induce the formation of pores when the transverse field is sufficiently strong (electroporation). Here, a phenomenological free energy is constructed to model the response of a BLM to a transverse static electric field. The model contains a continuum description of the membrane dipoles and a coupling between the headgroup dipoles and the membrane tilt. The membrane is found to become unstable through buckling modes, which are weakly coupled to thickness fluctuations in the membrane. The thickness fluctuations, along with the increase in interfacial area produced by membrane buckling, increase the probability of localized membrane breakdown, which may lead to pore formation. The instability is found to depend strongly on the strength of the coupling between the dipolar headgroups and the membrane tilt as well as the degree of dipolar ordering in the membrane.

  15. The onset of layer undulations in smectic A liquid crystals due to a strong magnetic field

    NASA Astrophysics Data System (ADS)

    Contreras, A.; Garcia-Azpeitia, C.; García-Cervera, C. J.; Joo, S.

    2016-08-01

    We investigate the effect of a strong magnetic field on a three dimensional smectic A liquid crystal. We identify a critical field above which the uniform layered state loses stability; this is associated to the onset of layer undulations. In a previous work García-Cervera and Joo (2012 Arch. Ration. Mech. Anal. 203 1–43), García-Cervera and Joo considered the two dimensional case and analyzed the transition to the undulated state via a simple bifurcation. In dimension n  =  3 the situation is more delicate because the first eigenvalue of the corresponding linearized problem is not simple. We overcome the difficulties inherent to this higher dimensional setting by identifying the irreducible representations for natural actions on the functional that take into account the invariances of the problem thus allowing for reducing the bifurcation analysis to a subspace with symmetries. We are able to describe at least two bifurcation branches, highlighting the richer landscape of energy critical states in the three dimensional setting. Finally, we analyze a reduced two dimensional problem, assuming the magnetic field is very strong, and are able to relate this to a model in micromagnetics studied in Alouges et al (2002 ESAIM Control Optim. Calc. Var. 8 31–68), from where we deduce the periodicity property of minimizers.

  16. Field evaluation of two commonly used slipmeters.

    PubMed

    Chang, Wen-Ruey; Cotnam, John P; Matz, Simon

    2003-01-01

    A variety of slipmeters have been used to assess the slipperiness of floor surfaces. International standards for the operation of slipmeters describe the protocol for a single measurement. These standards usually do not cover some of the critical elements in safety assessment such as methods for the selection of measurement locations and the necessary number of repeated measurements at each location. Furthermore, most of the slipmeters were evaluated in laboratory settings with new floor surfaces and artificial contaminants. Two commonly used slipmeters, the Brungraber Mark II and the English XL, were evaluated at actual worksites in this experiment. Four floor tiles in each of four different work areas in the kitchens of 18 fast food restaurants were selected for repeated measurements with these two slipmeters. The results indicated that sanding of footwear materials has a significant effect on the outcomes of friction measurements, and the tile-to-tile variations in friction in the same areas of restaurants were also mostly statistically significant. Significant local variation in friction among tiles in the same area could potentially increase the chances of slip and fall incidents. Both slipmeters used in this experiment could potentially have problems in the areas with grease, such as grill and fryer areas, since the build-up of grease during repeated strikes could alter the outcome of friction measured. PMID:12523805

  17. An evaluation of an empirical model for stall delay due to rotation for HAWTS

    SciTech Connect

    Tangler, J L; Selig, M S

    1997-07-01

    The objective of this study was to evaluate the Corrigan and Schillings stall delay model for predicting rotor performance for horizontal axis wind turbines. Two-dimensional (2D) wind tunnel characteristics with and without stall delay were used in the computer program PROP93 to predict performance for the NREL Combined Experiment Rotor (CER) and a lower solidity commercial machine. For the CER, predictions were made with a constant-chord/twisted blade and a hypothetical tapered/twisted blade. Results for the constant-chord/twisted blade were compared with CER data. Predicted performance using this empirical stall-delay method provided significant increases in peak power over 2D post-stall airfoil characteristics. The predicted peak power increase due to stall delay for the CER was found to be quite large (20% to 30%) as a result of its high blade solidity. For a more typical, lower-solidity commercial blade the predicted peak power increase was 15% to 20%. As described in the paper, correlation with test data was problematic due to factors not related to the stall-delay model.

  18. Incorporating uncertainty of distribution parameters due to sampling errors in flood-damage-reduction project evaluation

    NASA Astrophysics Data System (ADS)

    Su, Hsin-Ting; Tung, Yeou-Koung

    2013-03-01

    Epistemic uncertainty is a result of knowledge deficiency about the system. Sampling error exists when limited amounts of hydrologic data are used to estimate a T year event quantile. Both the natural randomness of hydrologic data and the sampling error in design quantile estimation contribute to the uncertainty in flood damage estimation. This paper presents a framework for evaluating a flood-damage-mitigation project in which both the hydrologic randomness and epistemic uncertainty due to sampling error are considered in flood damage estimation. Different risk-based decision-making criteria are used to evaluate project merits based on the mean, standard deviation, and probability distribution of the project net benefits. The results show that the uncertainty of the project net benefits is quite significant. Ignoring the data sampling error will underestimate the potential risk of each project. It can be clearly shown that adding data to existing sample observations leads to improved quality of information, enhanced reliability of the estimators, and reduced sampling error and uncertainty in the project net benefits. Through the proposed framework, the proper length of the extended record for risk reduction can be determined to achieve the required level of acceptable risk.

  19. EVALUATION OF RADIONUCLIDE ACCUMULATION IN SOIL DUE TO LONG-TERM IRRIGATION

    SciTech Connect

    De Wesley Wu

    2006-04-16

    Radionuclide accumulation in soil due to long-term irrigation is an important part of the model for predicting radiation dose in a long period of time. The model usually assumes an equilibrium condition in soil with a constant irrigation rate, so that radionuclide concentration in soil does not change with time and can be analytically solved. This method is currently being used for the dose assessment in the Yucca Mountain project, which requires evaluating radiation dose for a period of 10,000 years. There are several issues associated with the method: (1) time required for the equilibrium condition, (2) validity of constant irrigation rate, (3) agricultural land use for a long period of time, and (4) variation of a radionuclide concentration in water. These issues are evaluated using a numerical method with a simple model built in the GoldSim software. Some key radionuclides, Tc-99, Np-237, Pu-239, and Am-241 are selected as representative radionuclides. The results indicate that the equilibrium model is acceptable except for a radionuclide that requires long time to accumulate in soil and that its concentration in water changes dramatically with time (i.e. a sharp peak). Then the calculated dose for that radionuclide could be overestimated using the current equilibrium method.

  20. Estimating the change in asymptotic direction due to secular changes in the geomagnetic field

    NASA Technical Reports Server (NTRS)

    Flueckiger, E. O.; Smart, D. F.; Shea, M. A.; Gentile, L. C.; Bathurat, A. A.

    1985-01-01

    The concept of geomagnetic optics, as described by the asymptotic directions of approach, is extremely useful in the analysis of cosmic radiation data. However, when changes in cutoff occur as a result of evolution in the geomagnetic field, there are corresponding changes in the asymptotic cones of acceptance. A method is introduced of estimating the change in the asymptotic direction of approach for vertically incident cosmic ray particles from a reference set of directions at a specific epoch by considering the change in the geomagnetic cutoff.

  1. Evaluation of military field-water quality

    SciTech Connect

    Selleck, R.E.; Ungun, Z.; Chesler, G.; Diyamandoglu, V.; Marinas, B. . Sanitary Engineering and Environmental Health Research Lab.); Daniels, J.I. )

    1990-05-01

    A comparison is made between the performances of the 600-gph Reverse Osmosis Water Purification Unit (ROWPU) operated in the bypass mode and the Mobile Water Purification Unit (MWPU, frequently referred to as an ERDLATOR because the equipment was developed at the Engineer Research and Development Laboratory at Fort Belvoir, VA.) Generally, the performance of the MWPU is significantly better than the pretreatment units of the ROWPU in terms of removing both turbidity and pathogenic organisms. It is recommended that the practice of bypassing the reverse osmosis (RO) components of the ROWPU be avoided unless it can be demonstrated clearly that the cartridge filters will remove the cysts of infectious organisms effectively and reliably. If the ROWPU must be operated in the bypass mode, it is recommended that the dose of disinfectant used be made equal to that currently employed in the field for untreated raw water. The analytical methods used to determine total dissolved solids (TDS) and residual free chlorine with the new Water-Quality Monitor (WQM) are also reviewed briefly. The limitations of the methods used to calibrate the TDS and free-chlorine probes of the new WQM are discussed. 98 refs., 19 figs., 16 tabs.

  2. Electron residual energy due to stochastic heating in field-ionized plasma

    SciTech Connect

    Khalilzadeh, Elnaz; Yazdanpanah, Jam Chakhmachi, Amir; Jahanpanah, Jafar; Yazdani, Elnaz

    2015-11-15

    The electron residual energy originated from the stochastic heating in under-dense field-ionized plasma is investigated here. Initially, the optical response of plasma is modeled by using two counter-propagating electromagnetic waves. In this case, the solution of motion equation of a single electron indicates that by including the ionization, the electron with higher residual energy compared with that without ionization could be obtained. In agreement with chaotic nature of the motion, it is found that the electron residual energy will be significantly changed by applying a minor change in the initial conditions. Extensive kinetic 1D-3V particle-in-cell simulations have been performed in order to resolve full plasma reactions. In this way, two different regimes of plasma behavior are observed by varying the pulse length. The results indicate that the amplitude of scattered fields in a proper long pulse length is high enough to act as a second counter-propagating wave and trigger the stochastic electron motion. On the contrary, the analyses of intensity spectrum reveal the fact that the dominant scattering mechanism tends to Thomson rather than Raman scattering by increasing the pulse length. A covariant formalism is used to describe the plasma heating so that it enables us to measure electron temperature inside and outside of the pulse region.

  3. Vibroacoustic Response of Residential Housing due to Sonic Boom Exposure: A Summary of two Field Tests

    NASA Technical Reports Server (NTRS)

    Klos, Jacob; Buehrle, Ralph; Sullivan, Brenda; Gavin, Joseph; Salamone, Joseph; Haering, Edward A., jr.; Miller, Denise M.

    2008-01-01

    Two experiments have been performed to measure the vibroacoustic response of houses exposed to sonic booms. In 2006, an old home in the base housing area of Edwards Air Force Base, built around 1960 and demolished in 2007, was instrumented with 288 transducers. During a 2007 follow-on test, a newer home in the base housing area, built in 1997, was instrumented with 112 transducers. For each experiment, accelerometers were placed on walls, windows and ceilings in bedrooms of the house to measure the vibration response of the structure. Microphones were placed outside and inside the house to measure the excitation field and resulting interior sound field. The vibroacoustic response of each house was measured for sonic boom amplitudes spanning from 2.4 to 96 Pa (0.05 to 2 lbf/sq ft). The boom amplitudes were systematically varied using a unique dive maneuver of an F/A-18 airplane. In total, the database for both houses contains vibroacoustic response data for 154 sonic booms. In addition, several tests were performed with mechanical shaker excitation of the structure to characterize the forced response of the houses. The purpose of this paper is to summarize all the data from these experiments that are available to the research community, and to compare and contrast the vibroacoustic behavior of these two dissimilar houses.

  4. Excessive magnetic field flux density distribution from overhead isolated powerline conductors due to neutral line current.

    PubMed

    Netzer, Moshe

    2013-06-01

    Overhead isolated powerline conductors (hereinafter: "OIPLC") are the most compact form for distributing low voltage currents. From the known physics of magnetic field emission from 3-phase power lines, it is expected that excellent symmetry of the 120° shifted phase currents and where compact configuration of the 3-phase+neutral line exist, the phase current vectorial summation of the magnetic field flux density (MFFD) is expected to be extremely low. However, despite this estimation, an unexpectedly very high MFFD was found in at least three towns in Israel. This paper explains the reasons leading to high MFFD emissions from compact OIPLC and the proper technique to fix it. Analysis and measurement results had led to the failure hypothsis of neutral line poor connection design and poor grounding design of the HV-LV utility transformers. The paper elaborates on the low MFFD exposure level setup by the Israeli Environmental Protection Office which adopted a rather conservative precaution principal exposure level (2 mG averaged over 24 h). PMID:23675630

  5. Excitation of dayside chorus waves due to magnetic field line compression in response to interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Li, Wen; Thorne, Richard M.; Bortnik, Jacob; Ma, Qianli; An, Xin; Zhang, Xiao-jia; Angelopoulos, Vassilis; Ni, Binbin; Gu, Xudong; Fu, Song; Zhao, Zhengyu

    2015-10-01

    The excitation of magnetospheric whistler-mode chorus in response to interplanetary (IP) shocks is investigated using wave data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft. As an example, we show a typical chorus wave excitation following an IP shock event that was observed by THEMIS in the postnoon sector near the magnetopause on 3 August 2010. We then analyze characteristic changes during this event and perform a survey of similar events during the period 2008-2014 using the THEMIS and OMNI data set. Our statistical analysis demonstrates that the chorus wave excitation/intensification in response to IP shocks occurs only at high L shells (L > 8) on the dayside. We analyzed the variations of magnetic curvature following the arrival of the IP shock and found that IP shocks lead to more homogeneous background magnetic field configurations in the near-equatorial dayside magnetosphere; and therefore, the threshold of nonlinear chorus wave growth is likely to be reduced, favoring chorus wave generation. Our results provide the observational evidence to support the concept that the geomagnetic field line configuration plays a key role in the excitation of dayside chorus.

  6. Mobility overestimation due to gated contacts in organic field-effect transistors

    PubMed Central

    Bittle, Emily G.; Basham, James I.; Jackson, Thomas N.; Jurchescu, Oana D.; Gundlach, David J.

    2016-01-01

    Parameters used to describe the electrical properties of organic field-effect transistors, such as mobility and threshold voltage, are commonly extracted from measured current–voltage characteristics and interpreted by using the classical metal oxide–semiconductor field-effect transistor model. However, in recent reports of devices with ultra-high mobility (>40 cm2 V−1 s−1), the device characteristics deviate from this idealized model and show an abrupt turn-on in the drain current when measured as a function of gate voltage. In order to investigate this phenomenon, here we report on single crystal rubrene transistors intentionally fabricated to exhibit an abrupt turn-on. We disentangle the channel properties from the contact resistance by using impedance spectroscopy and show that the current in such devices is governed by a gate bias dependence of the contact resistance. As a result, extracted mobility values from d.c. current–voltage characterization are overestimated by one order of magnitude or more. PMID:26961271

  7. Mobility overestimation due to gated contacts in organic field-effect transistors.

    PubMed

    Bittle, Emily G; Basham, James I; Jackson, Thomas N; Jurchescu, Oana D; Gundlach, David J

    2016-01-01

    Parameters used to describe the electrical properties of organic field-effect transistors, such as mobility and threshold voltage, are commonly extracted from measured current-voltage characteristics and interpreted by using the classical metal oxide-semiconductor field-effect transistor model. However, in recent reports of devices with ultra-high mobility (>40 cm(2) V(-1) s(-1)), the device characteristics deviate from this idealized model and show an abrupt turn-on in the drain current when measured as a function of gate voltage. In order to investigate this phenomenon, here we report on single crystal rubrene transistors intentionally fabricated to exhibit an abrupt turn-on. We disentangle the channel properties from the contact resistance by using impedance spectroscopy and show that the current in such devices is governed by a gate bias dependence of the contact resistance. As a result, extracted mobility values from d.c. current-voltage characterization are overestimated by one order of magnitude or more. PMID:26961271

  8. Mobility overestimation due to gated contacts in organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Bittle, Emily G.; Basham, James I.; Jackson, Thomas N.; Jurchescu, Oana D.; Gundlach, David J.

    2016-03-01

    Parameters used to describe the electrical properties of organic field-effect transistors, such as mobility and threshold voltage, are commonly extracted from measured current-voltage characteristics and interpreted by using the classical metal oxide-semiconductor field-effect transistor model. However, in recent reports of devices with ultra-high mobility (>40 cm2 V-1 s-1), the device characteristics deviate from this idealized model and show an abrupt turn-on in the drain current when measured as a function of gate voltage. In order to investigate this phenomenon, here we report on single crystal rubrene transistors intentionally fabricated to exhibit an abrupt turn-on. We disentangle the channel properties from the contact resistance by using impedance spectroscopy and show that the current in such devices is governed by a gate bias dependence of the contact resistance. As a result, extracted mobility values from d.c. current-voltage characterization are overestimated by one order of magnitude or more.

  9. Screening of external magnetic perturbation fields due to sheared plasma flow

    NASA Astrophysics Data System (ADS)

    Li, L.; Liu, Y. Q.; Liang, Y.; Wang, N.; Luan, Q.; Zhong, F. C.; Liu, Y.

    2016-09-01

    Within the single fluid resistive magnetohydrodynamic model, systematic toroidal modelling efforts are devoted to investigate the plasma response induced screening of the applied external 3D magnetic field perturbations in the presence of sheared toroidal flow. One particular issue of interest is addressed, when the local flow speed approaches zero at the perturbation rational surface inside the plasma. Subtle screening physics, associated with the favourable averaged toroidal curvature effect (the GGJ effect (Glasser et al 1975 Phys. Fluids 7 875)), is found to play an essential role during slow flow near the rational surface by enhancing the screening at reduced flow. A strong cancellation effect between different terms of Ohm’s law is discovered, leading to different screening physics in the GGJ regime, as compared to that of conventional screening of the typical resistive-inertial regime occurring at faster flow. These modelling results may be applicable to interpret certain mode locking experiments, as well as type-I edge localized mode suppression experiments, with resonant magnetic field perturbations being applied to tokamak plasmas at low input toroidal torque.

  10. Electron residual energy due to stochastic heating in field-ionized plasma

    NASA Astrophysics Data System (ADS)

    Khalilzadeh, Elnaz; Yazdanpanah, Jam; Jahanpanah, Jafar; Chakhmachi, Amir; Yazdani, Elnaz

    2015-11-01

    The electron residual energy originated from the stochastic heating in under-dense field-ionized plasma is investigated here. Initially, the optical response of plasma is modeled by using two counter-propagating electromagnetic waves. In this case, the solution of motion equation of a single electron indicates that by including the ionization, the electron with higher residual energy compared with that without ionization could be obtained. In agreement with chaotic nature of the motion, it is found that the electron residual energy will be significantly changed by applying a minor change in the initial conditions. Extensive kinetic 1D-3V particle-in-cell simulations have been performed in order to resolve full plasma reactions. In this way, two different regimes of plasma behavior are observed by varying the pulse length. The results indicate that the amplitude of scattered fields in a proper long pulse length is high enough to act as a second counter-propagating wave and trigger the stochastic electron motion. On the contrary, the analyses of intensity spectrum reveal the fact that the dominant scattering mechanism tends to Thomson rather than Raman scattering by increasing the pulse length. A covariant formalism is used to describe the plasma heating so that it enables us to measure electron temperature inside and outside of the pulse region.

  11. SOI detector with drift field due to majority carrier flow - an alternative to biasing in depletion

    SciTech Connect

    Trimpl, M.; Deptuch, G.; Yarema, R.; /Fermilab

    2010-11-01

    This paper reports on a SOI detector with drift field induced by the flow of majority carriers. It is proposed as an alternative method of detector biasing compared to standard depletion. N-drift rings in n-substrate are used at the front side of the detector to provide charge collecting field in depth as well as to improve the lateral charge collection. The concept was verified on a 2.5 x 2.5 mm{sup 2} large detector array with 20 {micro}m and 40 {micro}m pixel pitch fabricated in August 2009 using the OKI semiconductor process. First results, obtained with a radioactive source to demonstrate spatial resolution and spectroscopic performance of the detector for the two different pixel sizes will be shown and compared to results obtained with a standard depletion scheme. Two different diode designs, one using a standard p-implantation and one surrounded by an additional BPW implant will be compared as well.

  12. Global Simulation of Proton Precipitation Due to Field Line Curvature During Substorms

    NASA Technical Reports Server (NTRS)

    Gilson, M. L.; Raeder, J.; Donovan, E.; Ge, Y. S.; Kepko, L.

    2012-01-01

    The low latitude boundary of the proton aurora (known as the Isotropy Boundary or IB) marks an important boundary between empty and full downgoing loss cones. There is significant evidence that the IB maps to a region in the magnetosphere where the ion gyroradius becomes comparable to the local field line curvature. However, the location of the IB in the magnetosphere remains in question. In this paper, we show simulated proton precipitation derived from the Field Line Curvature (FLC) model of proton scattering and a global magnetohydrodynamic simulation during two substorms. The simulated proton precipitation drifts equatorward during the growth phase, intensifies at onset and reproduces the azimuthal splitting published in previous studies. In the simulation, the pre-onset IB maps to 7-8 RE for the substorms presented and the azimuthal splitting is caused by the development of the substorm current wedge. The simulation also demonstrates that the central plasma sheet temperature can significantly influence when and where the azimuthal splitting takes place.

  13. Oscillation of electron mobility in parabolic double quantum well structure due to applied electric field

    SciTech Connect

    Sahoo, Narayan; Sahu, Trinath

    2014-12-15

    We show that oscillation of low temperature electron mobility μ can be obtained by applying an electric field F along the growth direction of the asymmetrically barrier delta doped Al{sub x}Ga{sub 1-x}As parabolic double quantum well structure. The drastic changes in the subband Fermi energies and distributions of subband wave functions as a function of F yield nonmonotonic intra- and intersubband scattering rate matrix elements mediated by intersubband effects. The oscillatory enhancement of μ, which is attributed to the subband mobilities governed by the ionized impurity scattering, magnifies with increase in well width and decrease in height of the parabolic structure potential. The results can be utilized for nanoscale low temperature device applications.

  14. Variations of Mars gravitational field and rotation due to seasonal CO2 exchange

    NASA Technical Reports Server (NTRS)

    Chao, B. Fong; Rubincam, David Parry

    1990-01-01

    About a quarter of the Martian atmospheric mass is exchanged between the atmosphere and the polar caps in the course of a Martian year: CO2 condenses to form (or add to) the polar caps in winter and sublimes into the atmosphere in summer. This paper studies the effect of this CO2 mass redistribution on Martian rotation and gravitational field. Two mechanisms are examined: (1) the waxing and waning of solid CO2 in the polar caps and (2) the geographical distribution of gaseous CO2 in the atmosphere. In particular, the net peak-to-peak changes in J2 and J3 over a Martian year are both found to be as much as about 6 x 10 to the -9th. A simulation suggests that these changes may be detected by the upcoming Mars Observer under favorable but realistic conditions.

  15. Mean force on a finite-sized spherical particle due to an acoustic field in a viscous compressible medium

    NASA Astrophysics Data System (ADS)

    Annamalai, Subramanian; Balachandar, S.; Parmar, Manoj K.

    2014-05-01

    An analytical expression to evaluate the second-order mean force (acoustic radiation force) on a finite-sized, rigid, spherical particle due to an acoustic wave is presented. The medium in which the particle is situated is taken to be both viscous and compressible. A far-field derivation approach has been used in determining the force, which is a function of the particle size, acoustic wavelength, and viscous boundary-layer thickness. It is assumed that the viscous length scale is negligibly small compared to the acoustic wavelength. The force expression presented here (i) reduces to the correct inviscid behavior (for both small- and finite-sized particles) and (ii) is identical to recent viscous results [M. Settnes and H. Bruus, Phys. Rev. E 85, 016327 (2012), 10.1103/PhysRevE.85.016327] for small-sized particles. Further, the computed force qualitatively matches the computational fluid dynamics (finite-element) results [D. Foresti, M. Nabavi, and D. Poulikakos, J. Fluid Mech. 709, 581 (2012), 10.1017/jfm.2012.350] for finite-sized particles. Additionally, the mean force is interpreted in terms of a multipole expansion. Subsequently, considering the fact that the force expansion is an infinite series, the number of terms that are required or adequate to capture the force to a specified accuracy is also provided as a function of the particle size to acoustic wavelength ratio. The dependence of the force on particle density, kinematic viscosity, and bulk viscosity of the fluid is also investigated. Here, both traveling and standing waves are considered.

  16. FIELD ANALYTICAL SCREENING PROGRAM: PCP METHOD - INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    This innovative technology evaluation report (ITER) presents information on the demonstration of the U.S. Environmental Protection Agency (EPA) Region 7 Superfund Field Analytical Screening Program (FASP) method for determining pentachlorophenol (PCP) contamination in soil and wa...

  17. FIELD ANALYTICAL SCREENING PROGRAM PCB METHOD: INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    This innovative technology evaluation report (ITER) presents information on the demonstration of the U.S. Environmental Protection Agency (EPA) Region 7 Superfund Field Analytical Screening Program (FASP) method for determining polychlorinated biphenyl (PCB) contamination in soil...

  18. Experimental observation of increased threshold electric field for runaway generation due to synchrotron radiation losses in the FTU tokamak

    SciTech Connect

    Martin-Solis, Jose Ramon; Sanchez, Raul; Esposito, Basilio

    2010-01-01

    The threshold electric field for runaway generation has been investigated during runaway suppression experiments by means of electron-cyclotron-resonance heating in the flattop phase of FTU discharges. Runaway suppression has been experimentally found to occur at electric fields substantially larger than those predicted by the relativistic collisional theory of runaway generation, E{sub R} = n{sub e}e{sup 3}ln{Lambda}/4{pi}{var_epsilon}{sub 0}{sup 2}m{sub e}c{sup 2}. These experimental results are consistent with an increase of the critical electric field due to the electron synchrotron radiation losses. No runaway electrons are found in FTU experiments below the radiation threshold. These results support evidence for a new threshold electric field for runaway generation that accounts for the effect of the synchrotron losses, and which should be considered when making predictions on runaway generation and mitigation in devices such as ITER.

  19. Electromagnetic Fields Due to a Loop Current in a CasedBorehole Surrounded by Uniform Whole Space

    SciTech Connect

    Lee, K.H.; Song, Y.

    1998-01-01

    Precise evaluation of electromagnetic (EM) response in steel-cased borehole is an essential first step towards developing techniques for casing parameter evaluation, which would ultimately help evaluating the formation response. In this report we demonstrate a numerical scheme for accurately computing EM responses in cased borehole environment. For improved numerical accuracy we use explicit representations of the electromagnetic spectra inside the borehole, in the casing, and in the formation. Instead of conventional Hankel transform, FFT is used to improve the numerical accuracy. The FFT approach allows us to compute fields at positions very close to the source loop, including the center of the transmitter loop.

  20. Experimental investigation of heating phenomena in linac mechanical interfaces due to RF field penetration

    SciTech Connect

    Fazio, M.V.; Reid, D.W.; Potter, J.M.

    1981-01-01

    In a high duty-factor, high-current, drift-tube linear accelerator, a critical interface exists between the drift-tube stem and the tank wall. This interface must provide vacuum integrity and RF continuity, while simultaneously allowing alignment flexibility. Because of past difficulties with RF heating of vacuum bellows and RF joints encountered by others, a paucity of available information, and the high reliability requirement for the Fusion Materials Irradiation Test (FMIT) accelerator, a program was initiated to study the problem. Because RF heating is the common failure mode, an attempt was made to find a correlation between the drift-tube-stem/linac-tank interface geometry and RF field penetration from the tank into the interface region. Experiments were performed at 80 MHz on an RF structure designed to simulate the conditions to which a drift-tube stem and vacuum bellows are exposed in a drift-tube linac. Additional testing was performed on a 367-MHz model of the FMIT prototype drift-tube linac. Experimental results, and a method to predict excessive RF heating, is presented. An experimentally tested solution to the problem is discussed.

  1. Near-Field Scattering due to Topography and Lateral Velocity Heterogeneity

    NASA Astrophysics Data System (ADS)

    Imperatori, Walter; Mai, Martin

    2014-05-01

    The scattering of seismic waves traveling in the Earth is not only caused by velocity heterogeneity, but also by rough surface topography. Both factors are known to play an important role on ground motion complexity even at short distances from the source. In this study, we simulate ground motion with a 3D finite-difference wave propagation solver in the frequency band 0-5 Hz using different rough topography models and realistic heterogeneous media characterized by Von Karman correlation functions. We analyze the characteristics of the scattered wave-field, focusing in particular on coda waves. Our study shows that topography and velocity heterogeneity scattering generate coda waves with different characteristics. We notice that, while coda waves originated by velocity heterogeneity have a more diffusive nature presenting envelope broadening as a result of forward scattering, coda waves caused by topography scattering are composed of more coherent body and surface waves reflected and diffracted by irregular topography surface. Results indicate that, for shallow sources, topography scattering can generate more intense early-coda waves at short and intermediate distances from the source. As distance increases, velocity heterogeneity scattering starts to dominate. However results show a rather high degree of variability as topography scattering is very sensitive to source position and features of the topography model. On the other hand, velocity perturbations generate more intense late-coda waves We conclude that topography scattering cannot be used as a proxy for velocity heterogeneity scattering.

  2. Microstructural changes in a cementitious membrane due to the application of a DC electric field.

    PubMed

    Covelo, Alba; Diaz, Belen; Freire, Lorena; Novoa, X Ramon; Perez, M Consuelo

    2008-07-01

    The use of electromigration techniques to accelerate chloride ions motion is commonly employed to characterise the permeability of cementitious samples to chlorides, a relevant parameter in reinforced concrete corrosion. This paper is devoted to the study of microstructure's changes occurring in mortar samples when submitted to natural diffusion and migration experiments. The application of an electric field reduces testing time in about one order of magnitude with respect to natural diffusion experiments. Nevertheless, the final sample's microstructure differs in both tests. Impedance Spectroscopy is employed for real time monitoring of microstructural changes. During migration experiments the global impedance undergoes important increase in shorter period of time compared to natural diffusion tests. So, the forced motion of ions through the concrete membrane induces significant variations in the porous structure, as confirmed by Mercury Intrusion Porosimetry. After migration experiments, an important increase in the capillary pore size (10-100 nm) was detected. Conversely, no relevant variations are found after natural diffusion tests. Results presented in this work cast doubt on the significance of diffusion coefficient values obtained under accelerated conditions. PMID:18569312

  3. Enhanced O2+ loss at Mars due to an ambipolar electric field from electron heating

    NASA Astrophysics Data System (ADS)

    Ergun, R. E.; Andersson, L. A.; Fowler, C. M.; Woodson, A. K.; Weber, T. D.; Delory, G. T.; Andrews, D. J.; Eriksson, A. I.; McEnulty, T.; Morooka, M. W.; Stewart, A. I. F.; Mahaffy, P. R.; Jakosky, B. M.

    2016-05-01

    Recent results from the MAVEN Langmuir Probe and Waves instrument suggest higher than predicted electron temperatures (Te) in Mars' dayside ionosphere above ~180 km in altitude. Correspondingly, measurements from Neutral Gas and Ion Mass Spectrometer indicate significant abundances of O2+ up to ~500 km in altitude, suggesting that O2+ may be a principal ion loss mechanism of oxygen. In this article, we investigate the effects of the higher Te (which results from electron heating) and ion heating on ion outflow and loss. Numerical solutions show that plasma processes including ion heating and higher Te may greatly increase O2+ loss at Mars. In particular, enhanced Te in Mars' ionosphere just above the exobase creates a substantial ambipolar electric field with a potential (eΦ) of several kBTe, which draws ions out of the region allowing for enhanced escape. With active solar wind, electron, and ion heating, direct O2+ loss could match or exceed loss via dissociative recombination of O2+. These results suggest that direct loss of O2+ may have played a significant role in the loss of oxygen at Mars over time.

  4. Scavenging of rodent carcasses following simulated mortality due to field applications of anticoagulant rodenticide.

    PubMed

    Montaz, Julie; Jacquot, Marion; Coeurdassier, Michaël

    2014-11-01

    Worldwide, agricultural uses of anticoagulant rodenticides (ARs) cause poisonings of non-target wildlife as observed in France where bromadiolone is used to control water vole outbreaks. Following bromadiolone field application, a part of the vole population may die aboveground of the treated plots and thus, can represent an important risk of secondary poisoning for scavengers. In this study, water voles were trapped in a non-treated area and their carcasses were placed aboveground in plots located in an area where a vole outbreak occurred. Then, the environmental persistence, the diurnal and nocturnal scavenging rates of water vole carcasses were assessed in autumn 2011 and in spring 2012. The diurnal scavenger species were also identified. The environmental persistence of the carcasses to reach at least a scavenging rate of 87.5 % was 0.5-1.5 day. The average rates of diurnal and nocturnal scavenging ranged from 67 to 100 % and 5 to 100 %, respectively. They depended on the composition of the scavenger community present near the monitored plots; diurnal scavenging rates being higher with corvids than with raptors. In autumn, the red kite and the common buzzard were the main scavengers in one of the plots, what suggests a high risk of poisoning for these raptors during post-nuptial migration. So, the collection of vole carcasses after treatments and the limitations of bromadiolone applications when high densities of predators/scavengers are observed could be implemented to mitigate the risks of secondary poisoning. PMID:25147048

  5. Difficulties in applying numerical simulations to an evaluation of occupational hazards caused by electromagnetic fields

    PubMed Central

    Zradziński, Patryk

    2015-01-01

    Due to the various physical mechanisms of interaction between a worker's body and the electromagnetic field at various frequencies, the principles of numerical simulations have been discussed for three areas of worker exposure: to low frequency magnetic field, to low and intermediate frequency electric field and to radiofrequency electromagnetic field. This paper presents the identified difficulties in applying numerical simulations to evaluate physical estimators of direct and indirect effects of exposure to electromagnetic fields at various frequencies. Exposure of workers operating a plastic sealer have been taken as an example scenario of electromagnetic field exposure at the workplace for discussion of those difficulties in applying numerical simulations. The following difficulties in reliable numerical simulations of workers’ exposure to the electromagnetic field have been considered: workers’ body models (posture, dimensions, shape and grounding conditions), working environment models (objects most influencing electromagnetic field distribution) and an analysis of parameters for which exposure limitations are specified in international guidelines and standards. PMID:26323781

  6. Difficulties in applying numerical simulations to an evaluation of occupational hazards caused by electromagnetic fields.

    PubMed

    Zradziński, Patryk

    2015-01-01

    Due to the various physical mechanisms of interaction between a worker's body and the electromagnetic field at various frequencies, the principles of numerical simulations have been discussed for three areas of worker exposure: to low frequency magnetic field, to low and intermediate frequency electric field and to radiofrequency electromagnetic field. This paper presents the identified difficulties in applying numerical simulations to evaluate physical estimators of direct and indirect effects of exposure to electromagnetic fields at various frequencies. Exposure of workers operating a plastic sealer have been taken as an example scenario of electromagnetic field exposure at the workplace for discussion of those difficulties in applying numerical simulations. The following difficulties in reliable numerical simulations of workers' exposure to the electromagnetic field have been considered: workers' body models (posture, dimensions, shape and grounding conditions), working environment models (objects most influencing electromagnetic field distribution) and an analysis of parameters for which exposure limitations are specified in international guidelines and standards. PMID:26323781

  7. Ferrofluid flow due to a rotating disk in the presence of a non-uniform magnetic field

    NASA Astrophysics Data System (ADS)

    Bhandari, A.; Kumar, V.

    2016-05-01

    The flow of a ferrofluid due to a rotating disk in the presence of a non-uniform magnetic field in the axial direction is studied through mathematical modeling of the problem. Contour and surface plots in the presence of 10 kilo-ampere/meter, 100 kilo-ampere/meter magnetization force are presented here for radial, tangential and axial velocity profiles, and results are also drawn for the magnetic field intensity. These results are compared with the ordinary case where magnetization force is absent.

  8. Field evaluation of rice varieties for resistance to major diseases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The development and use of improved disease resistant rice varieties remains of foremost importance to rice producers, with field evaluation under local environments essential. In this study, we evaluated new and existing varieties, potential releases, and Texas elite breeding lines for resistance t...

  9. DISPOSAL OF FLUE GAS DESULFURIZATION WASTES: EPA SHAWNEE FIELD EVALUATION

    EPA Science Inventory

    The report summarizes results of the flue gas desulfurization (FGD) waste disposal field evaluation project sponsored by EPA at TVA's Shawnee steam plant, Paducah, KY. This pilot-scale project, initiated in 1974 and completed in September 1980, evaluated methods and costs for dis...

  10. Evaluation of Activity Concentration Values and Doses due to the Transport of Low Level Radioactive Material

    SciTech Connect

    Rawl, Richard R; Scofield, Patricia A; Leggett, Richard Wayne; Eckerman, Keith F

    2010-04-01

    The International Atomic Energy Agency (IAEA) initiated an international Coordinated Research Project (CRP) to evaluate the safety of transport of naturally occurring radioactive material (NORM). This report presents the United States contribution to that IAEA research program. The focus of this report is on the analysis of the potential doses resulting from the transport of low level radioactive material. Specific areas of research included: (1) an examination of the technical approach used in the derivation of exempt activity concentration values and a comparison of the doses associated with the transport of materials included or not included in the provisions of Paragraph 107(e) of the IAEA Safety Standards, Regulations for the Safe Transport of Radioactive Material, Safety Requirements No. TS-R-1; (2) determination of the doses resulting from different treatment of progeny for exempt values versus the A{sub 1}/A{sub 2} values; and (3) evaluation of the dose justifications for the provisions applicable to exempt materials and low specific activity materials (LSA-I). It was found that the 'previous or intended use' (PIU) provision in Paragraph 107(e) is not risk informed since doses to the most highly exposed persons (e.g., truck drivers) are comparable regardless of intended use of the transported material. The PIU clause can also have important economic implications for co-mined ores and products that are not intended for the fuel cycle but that have uranium extracted as part of their industrial processing. In examination of the footnotes in Table 2 of TS-R-1, which identifies the progeny included in the exempt or A1/A2 values, there is no explanation of how the progeny were selected. It is recommended that the progeny for both the exemption and A{sub 1}/A{sub 2} values should be similar regardless of application, and that the same physical information should be used in deriving the limits. Based on the evaluation of doses due to the transport of low-level NORM

  11. Evaluation of counting error due to colony masking in bioaerosol sampling.

    PubMed

    Chang, C W; Hwang, Y H; Grinshpun, S A; Macher, J M; Willeke, K

    1994-10-01

    Colony counting error due to indistinguishable colony overlap (i.e., masking) was evaluated theoretically and experimentally. A theoretical model to predict colony masking was used to determine colony counting efficiency by Monte Carlo computer simulation of microorganism collection and development into CFU. The computer simulation was verified experimentally by collecting aerosolized Bacillus subtilis spores and examining micro- and macroscopic colonies. Colony counting efficiency decreased (i) with increasing density of collected culturable microorganisms, (ii) with increasing colony size, and (iii) with decreasing ability of an observation system to distinguish adjacent colonies as separate units. Counting efficiency for 2-mm colonies, at optimal resolution, decreased from 98 to 85% when colony density increased from 1 to 10 microorganisms cm-2, in contrast to an efficiency decrease from 90 to 45% for 5-mm colonies. No statistically significant difference (alpha = 0.05) between experimental and theoretical results was found when colony shape was used to estimate the number of individual colonies in a CFU. Experimental colony counts were 1.2 times simulation estimates when colony shape was not considered, because of nonuniformity of actual colony size and the better discrimination ability of the human eye relative to the model. Colony surface densities associated with high counting accuracy were compared with recommended upper plate count limits and found to depend on colony size and an observation system's ability to identify overlapped colonies. Correction factors were developed to estimate the actual number of collected microorganisms from observed colony counts.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7986046

  12. Bioremediation of hazardous wastes. Research, development, and field evaluations, 1995

    SciTech Connect

    Kremer, F.

    1995-09-01

    The U.S. Environmental Protection Agency`s (EPA`s) Office of Research and Development (ORD) hosted the eighth annual Symposium on Bioremediation of Hazardous Wastes: Research, Development, and Field Evaluations in Rye Brook, New York, August 8-10, 1995. In this document, abstracts of paper and poster presentations from the symposium are organized within five key research and program areas: Bioremediation Field Initiative; Field research; Performance evaluation; Pilot-scale research; and Process research. The last section of the document includes abstracts of presentations on bioremediation research performed as part of the Hazardous Substance Research Center (HSRC) program.

  13. Piezophotonic Switching Due to Local Field Effects in a Coherently Prepared Medium of Three-Level Atoms

    NASA Astrophysics Data System (ADS)

    Manka, Aaron S.; Dowling, Jonathan P.; Bowden, Charles M.; Fleischhauer, Michael

    1994-09-01

    We study the effect of near dipole-dipole interactions on the electric susceptibility of a coherently prepared three-level Λ system. We discuss the influence of atomic nonlinearities on the recently predicted enhancement of the absorptionless index of refraction and inversionless gain due to local field effects [J.P. Dowling and C.M. Bowden,

    Phys. Rev. Lett. 70 1421 1993
    ] and predict a density dependent, or piezophotonic, switching between absorption and amplification.

  14. Evaluation of Vulnerable Zones in Puerto Vallarta due to a Local Tsunami

    NASA Astrophysics Data System (ADS)

    Trejo, E.; Nuñez Cornu, F. J., II; Ortiz, M.

    2015-12-01

    Based in the high possibility of occurrence of a tsunamigenic earthquake of magnitude 8.0Mw offshore from the northern coast of Jalisco and Bahía de Banderas, Mexico. The vulnerability of Puerto Vallarta to a direct flood hazard associated to the tsunami is evaluated. Assuming a simplified model of the seismic source a numerical method is used to calculate the tsunami run-up and the extent of flooding in Puerto Vallarta area. Floods heights and arrival times in the first ten hours after the earthquake and flood boundaries in different watersheds were estimated. This method was previously testing, modeling the October 9, 1995, Jalisco Earthquake and Tsunami, the results obtained were similar to the field observations and testimonies performed in 20 sites along 100 km on the coast of Jalisco, related to the height and flood extension reached during the tsunami. To estimate the vulnerability the following variables were considered: distribution of population density, population by age or physical limitation, housing characteristics, level of education, cost of goods in the affected area, location of key facilities, cost of cleaning the affected area, and change of land use policy in the Puerto Vallarta area. The study indicates that the vulnerability is very high in the Salado basin, and high in the Pitillal and Mascota-Ameca basins.

  15. Use of element model to evaluate transmissibility reduction due to barriers

    SciTech Connect

    Svanes, T.; South, D.; Dronen, O.M.

    1997-08-01

    Water breakthrough has been observed a year earlier than expected in the productive Oseberg Formation in the Veslefrikk Field. Production data revealed extensive water override, whereas the opposite situation was expected based on a homogeneous and coarse flow simulation model. A new model was developed to include geological heterogeneities using a simple upscaling method. The Oseberg Fm. consists of an upper homogeneous unit (zone 2) and a lower unit containing thin barriers of shale and calcite cemented sandstone (zone 1). The barrier content varies laterally. When barriers are distributed in a complex 3D pattern, they reduce the upscaled horizontal transmissibility more than what is obtained by multiplying the sand permeability by the net-to-gross ratio (N/G). However, the transmissibility reduction strongly depends on the spatial distribution of barriers and their geometry. Therefore, a fine scale element model was used to derive the average transmissibility reduction as a function of N/G for alternative geological descriptions of the barriers. A geo-statistical method called General Marked Point Process was used to generate the fine scale descriptions. This work has resulted in a simple upscaling routine for horizontal transmissibility, which represents an effective bridge between geological evaluation of uncertainties and fluid flow simulation. The method combines geo-statistical and deterministic modelling in an elegant manner, recognising that most often these methods complement one another.

  16. Superior bit error rate and jitter due to improved switching field distribution in exchange spring magnetic recording media

    NASA Astrophysics Data System (ADS)

    Suess, D.; Fuger, M.; Abert, C.; Bruckner, F.; Vogler, C.

    2016-06-01

    We report two effects that lead to a significant reduction of the switching field distribution in exchange spring media. The first effect relies on a subtle mechanism of the interplay between exchange coupling between soft and hard layers and anisotropy that allows significant reduction of the switching field distribution in exchange spring media. This effect reduces the switching field distribution by about 30% compared to single-phase media. A second effect is that due to the improved thermal stability of exchange spring media over single-phase media, the jitter due to thermal fluctuation is significantly smaller for exchange spring media than for single-phase media. The influence of this overall improved switching field distribution on the transition jitter in granular recording and the bit error rate in bit-patterned magnetic recording is discussed. The transition jitter in granular recording for a distribution of Khard values of 3% in the hard layer, taking into account thermal fluctuations during recording, is estimated to be a = 0.78 nm, which is similar to the best reported calculated jitter in optimized heat-assisted recording media.

  17. Superior bit error rate and jitter due to improved switching field distribution in exchange spring magnetic recording media.

    PubMed

    Suess, D; Fuger, M; Abert, C; Bruckner, F; Vogler, C

    2016-01-01

    We report two effects that lead to a significant reduction of the switching field distribution in exchange spring media. The first effect relies on a subtle mechanism of the interplay between exchange coupling between soft and hard layers and anisotropy that allows significant reduction of the switching field distribution in exchange spring media. This effect reduces the switching field distribution by about 30% compared to single-phase media. A second effect is that due to the improved thermal stability of exchange spring media over single-phase media, the jitter due to thermal fluctuation is significantly smaller for exchange spring media than for single-phase media. The influence of this overall improved switching field distribution on the transition jitter in granular recording and the bit error rate in bit-patterned magnetic recording is discussed. The transition jitter in granular recording for a distribution of Khard values of 3% in the hard layer, taking into account thermal fluctuations during recording, is estimated to be a = 0.78 nm, which is similar to the best reported calculated jitter in optimized heat-assisted recording media. PMID:27245287

  18. Superior bit error rate and jitter due to improved switching field distribution in exchange spring magnetic recording media

    PubMed Central

    Suess, D.; Fuger, M.; Abert, C.; Bruckner, F.; Vogler, C.

    2016-01-01

    We report two effects that lead to a significant reduction of the switching field distribution in exchange spring media. The first effect relies on a subtle mechanism of the interplay between exchange coupling between soft and hard layers and anisotropy that allows significant reduction of the switching field distribution in exchange spring media. This effect reduces the switching field distribution by about 30% compared to single-phase media. A second effect is that due to the improved thermal stability of exchange spring media over single-phase media, the jitter due to thermal fluctuation is significantly smaller for exchange spring media than for single-phase media. The influence of this overall improved switching field distribution on the transition jitter in granular recording and the bit error rate in bit-patterned magnetic recording is discussed. The transition jitter in granular recording for a distribution of Khard values of 3% in the hard layer, taking into account thermal fluctuations during recording, is estimated to be a = 0.78 nm, which is similar to the best reported calculated jitter in optimized heat-assisted recording media. PMID:27245287

  19. An evaluation of recent internal field models. [of earth magnetism

    NASA Technical Reports Server (NTRS)

    Mead, G. D.

    1979-01-01

    The paper reviews the current status of internal field models and evaluates several recently published models by comparing their predictions with annual means of the magnetic field measured at 140 magnetic observatories from 1973 to 1977. Three of the four models studied, viz. AWC/75, IGS/75, and Pogo 8/71, were nearly equal in their ability to predict the magnitude and direction of the current field. The fourth model, IGRF 1975, was significantly poorer in its ability to predict the current field. All models seemed to be able to extrapolate predictions quite well several years outside the data range used to construct the models.

  20. The Evaluation Principles of Ralph W. Tyler: Rationale for the Field of Program Evaluation.

    ERIC Educational Resources Information Center

    Vernazza, Martha Elin

    There is a need for a set of organizing principles that will provide a clear rationale for the field of program evaluation. It is contended that the concept of evaluation promoted by Ralph W. Tyler, pioneer in the field, suggests such a set of principles. Data were derived from a two-year prescriptive case study of Tyler's contributions through…

  1. ¹⁴N Quadrupole Resonance line broadening due to the earth magnetic field, occuring only in the case of an axially symmetric electric field gradient tensor.

    PubMed

    Aissani, Sarra; Guendouz, Laouès; Marande, Pierre-Louis; Canet, Daniel

    2015-01-01

    As demonstrated before, the application of a weak static B0 magnetic field (less than 10 G) may produce definite effects on the ¹⁴N Quadrupole Resonance line when the electric field gradient tensor at the nitrogen nucleus level is of axial symmetry. Here, we address more precisely the problem of the relative orientation of the two magnetic fields (the static field and the radio-frequency field of the pure NQR experiment). For a field of 6G, the evolution of the signal intensity, as a function of this relative orientation, is in very good agreement with the theoretical predictions. There is in particular an intensity loss by a factor of three when going from the parallel configuration to the perpendicular configuration. By contrast, when dealing with a very weak magnetic field (as the earth field, around 0.5 G), this effect drops to ca. 1.5 in the case Hexamethylenetetramine (HMT).This is explained by the fact that the Zeeman shift (due to the very weak magnetic field) becomes comparable to the natural line-width. The latter can therefore be determined by accounting for this competition. Still in the case of HMT, the estimated natural line-width is half the observed line-width. The extra broadening is thus attributed to earth magnetic field. The latter constitutes therefore the main cause of the difference between the natural transverse relaxation time (T₂) and the transverse relaxation time derived from the observed line-width (T₂(⁎)). PMID:25910551

  2. [Unilateral visual field defect due to optic nerve compression by sclerotic internal carotid artery: a case report].

    PubMed

    Uchino, M; Nemoto, M; Ohtsuka, T; Kuramitsu, T; Isobe, Y

    1999-02-01

    A case of unilateral visual field defect due to optic nerve compression by a sclerotic internal carotid artery was reported. A 71-year-old woman was admitted to our department because of constricted visual field of the right eye. MRI showed elevation of the right optic nerve compressed by an internal carotid artery. The right carotid angiography revealed elevation and distortion of the C1-2 portion. Frontal craniotomy was carried out and the optic nerve was visualized on this side. The right optic nerve was found to have been compressed by the sclerotic internal carotid artery. The optic canal was then unroofed. The post-operative course was uneventful. The visual field was improved. When last seen 6 months after surgery, her visual field remained in the improved condition. Nasal field abnormalities are most frequently encountered in retinal and anterior optic nerve pathology. Our success in improving the visual field disturbance may be accounted for by the fact that the preoperative period was short and the operation was performed before atrophy of ocular fundi occurred. Nasal field loss caused by intracranial lesions of the optic pathway is rare. It is probably impossible to determine degree of the symptomatology caused by direct-pressure compression as opposed to that caused by ischemia secondary to occlusion of small arterial supply branches. Vascular compressive neuropathy of optic nerve should not be diagnosed simply by the radiological finding of the optic nerve dislocation. However, optic nerve compression by surrounding arteries should be remembered as one of the possible causes of visual field defect which needs to be treated surgically. PMID:10065453

  3. FIELD EVALUATION OF LOW-EMISSION COAL BURNER TECHNOLOGY ON UTILITY BOILERS VOLUME III. FIELD EVALUATIONS

    EPA Science Inventory

    The report gives results of field tests conducted to determine the emission characteristics of a Babcock and Wilcox Circular burner and Dual Register burner (DRB). The field tests were performed at two utility boilers, generally comparable in design and size except for the burner...

  4. FIELD EVALUATION OF LOW-EMISSION COAL BURNER TECHNOLOGY ON UTILITY BOILERS; VOLUME III. FIELD EVALUATION

    EPA Science Inventory

    The report gives results of field tests conducted to determine the emission characteristics of a Babcock and Wilcox Circular burner and Dual Register burner (DRB). The field tests were performed at two utility boilers, generally comparable in design and size except for the burner...

  5. Experimental Evaluation of the Change in Fracture Geometry and Permeability Due to Shearing.

    NASA Astrophysics Data System (ADS)

    Crandall, D.; Gill, M.; Moore, J.; Tennant, B.; Bromhal, G. S.

    2014-12-01

    Fractures often provide the preferential flow paths through geologic media. As such, an understanding of what influences fracture permeability is critically important to describing sub-surface flows. Numerous studies have been reported which illustrate the importance of rock fracture geometry on the permeability of fractures, in particular the influence of zero aperture locations within the fracture aperture. increasing the tortuosity of flow through a fracture and subsequently decreasing the fracture permeability. Fractures and faults can shear due to increased transverse stresses, or an increase of fluid pressure within a fracture reducing the effective forces stopping fracture slippage. This behavior has been widely observed in many seismic events. How small scale shearing events influence the permeability of fracture is not well known though, as few experimental tests have been performed that enable the dynamic change in a fractured rock position while simultaneously measuring the permeability across the fracture. This talk describes resent research at the National Energy Technology Laboratory in Morgantown, West Virginia where fractured rock cores have been experimentally sheared and the permeability through the fracture has been measured. In addition, these fractured cores were imaged with computed tomography scanning to understand what geometric alterations to the fracture structure influence the shearing induced changes to fracture permeability. Both shale and sandstone fractured cores have been evaluated with this unique core flow apparatus, and relationships between the shearing distance, rock type, and initial fracture geometry are being developed to provide guidance on understanding and modeling sheared fracture permeability changes in CO2 sequestration and other sub-surface activities.

  6. Shock formation processes due to interactions of two plasmas in a magnetic field and modified two-stream instabilities

    SciTech Connect

    Toida, Mieko; Uragami, Tatsunori

    2013-11-15

    The study of interactions of exploding and surrounding plasmas in an external magnetic field [K. Yamauchi and Y. Ohsawa, Phys. Plasmas 14, 053110 (2007)] is verified with two-dimensional (2D) electromagnetic particle simulations, for a case in which the initial velocity of the exploding plasma is perpendicular to the external magnetic field. The 2D simulations show essentially the same shock-formation processes as those in the previous one-dimensional simulation, including penetration of exploding ions into surrounding plasma, formation of a strong magnetic-field pulse due to deceleration of the exploding ions, ion reflection by the pulse, and subsequent splitting of the pulse into two magnetosonic pulses which then develop into forward and reverse shock waves. Furthermore, the 2D structure of electromagnetic fields in the region, where the exploding and surrounding ions overlap, is investigated with particular attention to the linear and nonlinear evolution of modified two-stream instabilities in the magnetic field that is being gradually compressed. The effects of these instabilities on ion reflection and on 2D magnetic fluctuations in the two generated pulses are also discussed.

  7. Evaluation of different field methods for measuring soil water infiltration

    NASA Astrophysics Data System (ADS)

    Pla-Sentís, Ildefonso; Fonseca, Francisco

    2010-05-01

    Soil infiltrability, together with rainfall characteristics, is the most important hydrological parameter for the evaluation and diagnosis of the soil water balance and soil moisture regime. Those balances and regimes are the main regulating factors of the on site water supply to plants and other soil organisms and of other important processes like runoff, surface and mass erosion, drainage, etc, affecting sedimentation, flooding, soil and water pollution, water supply for different purposes (population, agriculture, industries, hydroelectricity), etc. Therefore the direct measurement of water infiltration rates or its indirect deduction from other soil characteristics or properties has become indispensable for the evaluation and modelling of the previously mentioned processes. Indirect deductions from other soil characteristics measured under laboratory conditions in the same soils, or in other soils, through the so called "pedo-transfer" functions, have demonstrated to be of limited value in most of the cases. Direct "in situ" field evaluations have to be preferred in any case. In this contribution we present the results of past experiences in the measurement of soil water infiltration rates in many different soils and land conditions, and their use for deducing soil water balances under variable climates. There are also presented and discussed recent results obtained in comparing different methods, using double and single ring infiltrometers, rainfall simulators, and disc permeameters, of different sizes, in soils with very contrasting surface and profile characteristics and conditions, including stony soils and very sloping lands. It is concluded that there are not methods universally applicable to any soil and land condition, and that in many cases the results are significantly influenced by the way we use a particular method or instrument, and by the alterations in the soil conditions by the land management, but also due to the manipulation of the surface

  8. Technical Evaluation of the NASA Model for Cancer Risk to Astronauts Due to Space Radiation

    NASA Technical Reports Server (NTRS)

    2012-01-01

    At the request of NASA, the National Research Council's (NRC's) Committee for Evaluation of Space Radiation Cancer Risk Model reviewed a number of changes that NASA proposes to make to its model for estimating the risk of radiation-induced cancer in astronauts. The NASA model in current use was last updated in 2005, and the proposed model would incorporate recent research directed at improving the quantification and understanding of the health risks posed by the space radiation environment. NASA's proposed model is defined by the 2011 NASA report Space Radiation Cancer Risk Projections and Uncertainties 2010 (Cucinotta et al., 2011). The committee's evaluation is based primarily on this source, which is referred to hereafter as the 2011 NASA report, with mention of specific sections or tables cited more formally as Cucinotta et al. (2011). The overall process for estimating cancer risks due to low linear energy transfer (LET) radiation exposure has been fully described in reports by a number of organizations. They include, more recently: (1) The "BEIR VII Phase 2" report from the NRC's Committee on Biological Effects of Ionizing Radiation (BEIR) (NRC, 2006); (2) Studies of Radiation and Cancer from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2006), (3) The 2007 Recommendations of the International Commission on Radiological Protection (ICRP), ICRP Publication 103 (ICRP, 2007); and (4) The Environmental Protection Agency s (EPA s) report EPA Radiogenic Cancer Risk Models and Projections for the U.S. Population (EPA, 2011). The approaches described in the reports from all of these expert groups are quite similar. NASA's proposed space radiation cancer risk assessment model calculates, as its main output, age- and gender-specific risk of exposure-induced death (REID) for use in the estimation of mission and astronaut-specific cancer risk. The model also calculates the associated uncertainties in REID. The general approach for

  9. Technical Evaluation of the NASA Model for Cancer Risk to Astronauts Due to Space Radiation

    NASA Technical Reports Server (NTRS)

    2012-01-01

    At the request of NASA, the National Research Council's (NRC's) Committee for Evaluation of Space Radiation Cancer Risk Model1 reviewed a number of changes that NASA proposes to make to its model for estimating the risk of radiation-induced cancer in astronauts. The NASA model in current use was last updated in 2005, and the proposed model would incorporate recent research directed at improving the quantification and understanding of the health risks posed by the space radiation environment. NASA's proposed model is defined by the 2011 NASA report Space Radiation Cancer Risk Projections and Uncertainties--2010 . The committee's evaluation is based primarily on this source, which is referred to hereafter as the 2011 NASA report, with mention of specific sections or tables. The overall process for estimating cancer risks due to low linear energy transfer (LET) radiation exposure has been fully described in reports by a number of organizations. The approaches described in the reports from all of these expert groups are quite similar. NASA's proposed space radiation cancer risk assessment model calculates, as its main output, age- and gender-specific risk of exposure-induced death (REID) for use in the estimation of mission and astronaut-specific cancer risk. The model also calculates the associated uncertainties in REID. The general approach for estimating risk and uncertainty in the proposed model is broadly similar to that used for the current (2005) NASA model and is based on recommendations by the National Council on Radiation Protection and Measurements. However, NASA's proposed model has significant changes with respect to the following: the integration of new findings and methods into its components by taking into account newer epidemiological data and analyses, new radiobiological data indicating that quality factors differ for leukemia and solid cancers, an improved method for specifying quality factors in terms of radiation track structure concepts as

  10. Evaluation of field dental equipment in a deployment environment.

    PubMed

    Charlton, David G; Ehrlich, A Dale; Ragain, James C; Lyles, Mark B; Roberts, Howard W

    2006-03-01

    Dental officers and technicians must have reliable, durable, well-performing field dental equipment to enable them to provide dental care to deployed troops in operational environments. Unfortunately, no organized program exists to test such equipment before its purchase and use in the field. This article presents the results of a project conducted by the Naval Institute for Dental and Biomedical Research and the Air Force Dental Evaluation and Consultation Service to evaluate commercially available field dental equipment through laboratory testing and clinical-user evaluations in theater. The purpose of this 2-year project was to identify the best-performing and most cost-effective field dental equipment for possible future procurement. Initial laboratory testing was performed at the Naval Institute for Dental and Biomedical Research, and the equipment was then shipped to Kuwait for in-theater environmental and clinical-user testing. A seven-member scientific team of military dental officers and technicians was deployed for 1 month to perform in-theater testing under regional environmental conditions and to coordinate clinical-user evaluations. The testing provided beneficial results by identifying equipment that performed properly and equipment that exhibited shortcomings serious enough to render it inadequate for operational use. It is recommended that the project serve as a model for future testing and evaluation of medical/dental equipment by all of the military services. PMID:16602527

  11. Highly localized strain fields due to planar defects in epitaxial SrBi2Nb2O9 thin films

    NASA Astrophysics Data System (ADS)

    Boulle, A.; Guinebretière, R.; Dauger, A.

    2005-04-01

    Thin films of (00l) oriented SrBi2Nb2O9 epitaxially grown on SrTiO3 by sol-gel spin coating have been studied by means of high-resolution x-ray diffraction reciprocal space mapping. It is shown that these materials contain highly localized heterogeneous strain fields due to imperfect stacking faults (i.e., faults that do not propagate throughout the crystallites building up the film). In the film plane, the strain fields are confined to 11 nm wide regions and characterized by a vertical displacement of 0.18c (where c is the cell parameter) showing that the stacking faults are mainly composed of one additional (or missing) perovskite layer. Prolonged thermal annealing at 700 °C strongly reduces the density of stacking faults and yields a more uniform strain distribution within the film volume without inducing significant grain growth.

  12. Formulas Pertinent to the Calculation of Flow-Field Effects at Supersonic Speeds Due to Wing Thickness

    NASA Technical Reports Server (NTRS)

    Margolis, Kenneth; Elliott, Miriam H.

    1959-01-01

    Expressions based on linearized supersonic-flow theory are derived for the perturbation velocity potential in space due to wing thickness for rectangular wings with biconvex airfoil sections and for arrow, delta, and quadrilateral wings with wedge-type airfoil sections. The complete range of supersonic speeds is considered subject to a minor aspect-ratio-Mach number restriction for the rectangular plan form and to the condition that the trailing edge is supersonic for the sweptback wings. The formulas presented can be utilized in determining the induced-flow characteristics at any point in the field and are readily adaptable for either numerical computation or analytical determination of any velocity components desired.

  13. Exploration of Quench Initiation Due to Intentional Geometrical Defects in a High Magnetic Field Region of an SRF Cavity

    SciTech Connect

    J. Dai, K. Zhao, G.V. Eremeev, R.L. Geng, A.D. Palczewski; Dai, J.; Palczewski, A. D.; Eremeev, G. V.; Geng, R. L.; Zhao, K.

    2011-07-01

    A computer program which was used to simulate and analyze the thermal behaviors of SRF cavities has been developed at Jefferson Lab using C++ code. This code was also used to verify the quench initiation due to geometrical defects in high magnetic field region of SRF cavities. We built a CEBAF single cell cavity with 4 artificial defects near equator, and this cavity has been tested with T-mapping. The preheating behavior and quench initiation analysis of this cavity will be presented here using the computer program.

  14. First in situ evidence of electron pitch angle scattering due to magnetic field line curvature in the Ion diffusion region

    NASA Astrophysics Data System (ADS)

    Zhang, Y. C.; Shen, C.; Marchaudon, A.; Rong, Z. J.; Lavraud, B.; Fazakerley, A.; Yao, Z.; Mihaljcic, B.; Ji, Y.; Ma, Y. H.; Liu, Z. X.

    2016-05-01

    Theory predicts that the first adiabatic invariant of a charged particle may be violated in a region of highly curved field lines, leading to significant pitch angle scattering for particles whose gyroradius are comparable to the radius of the magnetic field line curvature. This scattering generates more isotropic particle distribution functions, with important impacts on the presence or absence of plasma instabilities. Using magnetic curvature analysis based on multipoint Cluster spacecraft observations, we present the first investigation of magnetic curvature in the vicinity of an ion diffusion region where reconnected field lines are highly curved. Electrons at energies > 8 keV show a clear pitch angle ordering between bidirectional and trapped distribution in surrounding regions, while we show that in the more central part of the ion diffusion region electrons above such energies become isotropic. By contrast, colder electrons (~1 keV) retain their bidirectional character throughout the diffusion regions. The calculated adiabatic parameter K2 for these electrons is in agreement with theory. This study provides the first observational evidence for particle pitch angle scattering due to magnetic field lines with well characterized curvature in a space plasma.

  15. Evaluation of different enzyme-linked immunosorbent assays for the diagnosis of brucellosis due to Brucella melitensis in sheep.

    PubMed

    García-Bocanegra, Ignacio; Allepuz, Alberto; Pérez, Julio José; Alba, Anna; Giovannini, Armando; Arenas, Antonio; Candeloro, Luca; Pacios, Alberto; Saez, José Luís; González, Miguel Ángel

    2014-03-01

    Six serological assays for the diagnosis of ovine brucellosis, due to Brucella melitensis were evaluated. Reference serum samples from sheep of known B. melitensis infection status (n=118) were assessed using the Rose Bengal test (RBT), complement fixation test (CFT) and four commercial enzyme-linked immunosorbent assays (ELISAs), including two indirect ELISAs (iELISAs), one competitive ELISA (cELISA) and one blocking ELISA (bELISA). The highest differential positive rates (DPR) were obtained with the cELISA and bELISA, while the lowest DPR was estimated using iELISAs. A latent class analysis was performed to estimate the accuracy of the CFT, RBT and bELISA using 1827 sera from sheep undergoing testing as part of a surveillance and control programme. Lower sensitivity and specificity were obtained for the three serological tests when the field samples were used. A higher DPR was achieved by the CFT, compared to bELISA and RBT. The results suggest that ELISAs, and particularly the bELISA, might be suitable for inclusion in the European Union legislation on intra-community trade for diagnosing B. melitensis infection in sheep, as it has a similar test performance compared to the RBT. PMID:24456797

  16. EVALUATION OF TEMPORAL VARIATIONS IN HYDRAULIC CAPTURE DUE TO CHANGING FLOW PATTERNS USING MAPPING AND MODELING TECHNIQUES

    SciTech Connect

    SPILIOTOPOULOS AA; SWANSON LC; SHANNON R; TONKIN MJ

    2011-04-07

    Robust performance evaluation represents one of the most challenging aspects of groundwater pump-and-treat (P&T) remedy implementation. In most cases, the primary goal of the P&T system is hydraulic containment, and ultimately recovery, of contaminants to protect downgradient receptors. Estimating the extent of hydraulic containment is particularly challenging under changing flow patterns due to variable pumping, boundaries and/or other conditions. We present a systematic approach to estimate hydraulic containment using multiple lines of evidence based on (a) water-level mapping and (b) groundwater modeling. Capture Frequency Maps (CFMs) are developed by particle tracking on water-level maps developed for each available water level data set using universal kriging. In a similar manner, Capture Efficiency Maps (CEMs) are developed by particle tracking on water-levels calculated using a transient groundwater flow model: tracking is undertaken independently for each stress period using a very low effective porosity, depicting the 'instantaneous' fate of each particle each stress period. Although conceptually similar, the two methods differ in their underlying assumptions and their limitations: their use together identifies areas where containment may be reliable (i.e., where the methods are in agreement) and where containment is uncertain (typically, where the methods disagree). A field-scale example is presented to illustrate these concepts.

  17. Evaluation of Brine Migration Risks Due to CO2 Injection - an Integrated Natural and Social Science Modeling Approach

    NASA Astrophysics Data System (ADS)

    Noack, V.; Kissinger, A.; Class, H.; Knopf, S.; Konrad, W.; Scheer, D.

    2014-12-01

    Evaluation of possible risks for shallow groundwater systems caused by brine displacement due to CO2 injection requires an investigation of possible vertical pathways in regional-scale structural settings. The project CO2BRIM investigates this crucial issue in collaboration with external stakeholders to integrate expert feedback on migration scenarios. To evaluate possible brine displacement scenarios we construct a regional-scale 3D structural model based on data which represent a typical geological setting of the North German Basin. The model has a horizontal size of 39 km times 58 km and includes 11 geological layers from the Permian Zechstein salt up to the Quaternary. It comprises an anticlinal structure on top of a salt pillow and an elongated salt wall that dissect the overburden. For the risk scenarios we include discontinuities in the regionally important Rupelian aquitard (Tertiary) and a transition zone along the salt flank as such discontinuities are supposed to provide permeable pathways for brines which could reach shallow drinking water horizons. Based on this model we develop scenarios in which we vary for example hydro-geological parameters of the geological discontinuities, the injection rate and the initial state of the system in terms of the salinity distribution. Furthermore we compare different levels of model complexity with regard to the physical processes considered and their effects on our results. During the process of scenario development, external experts were invited to participate and share knowledge and concerns on both brine migration risks and possible migration paths and mechanisms. The results may help in site selection as they provide improved knowledge of pressure build-up in the reservoir and the overburden for such complex geological systems. Additionally, we want to identify the level of model complexity which is sufficient for this kind of setting with regard to the limited data availability at hand for the far field.

  18. Evaluation in the Field: The Need for Site Visit Standards

    ERIC Educational Resources Information Center

    Patton, Michael Quinn

    2015-01-01

    Our understanding of programs is enhanced when trained, skilled, and observant evaluators go "into the field"--the real world where programs are conducted--paying attention to what's going on, systematically documenting what they see, and reporting what they learn. The article opens by presenting and illustrating twelve reasons for…

  19. Montana CETA Field Learning Program. Fiscal Year 1980. Evaluation Report.

    ERIC Educational Resources Information Center

    Wooden, Richard E.

    Evaluation of the CETA/EBCE (Comprehensive Employment and Training Act/Experience Based Career Education) Field Learning Program at eight sites in Montana showed the program to be successful in helping high school students explore careers. The system was generally successful in achieving program outcome objectives: varied types of students were…

  20. 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...

  1. Evaluation of electrical fields inside a biological structure.

    PubMed Central

    Drago, G. P.; Ridella, S.

    1982-01-01

    A digital computer simulation has been carried out of exposure of a cell, modelled as a multilayered spherical structure, to an alternating electrical field. Electrical quantities of possible biological interest can be evaluated everywhere inside the cell. A strong frequency selective behaviour in the range 0-10 MHz has been obtained. PMID:6279135

  2. EVALUATING THE SUCCESS OF PHOSPHORUS MANAGEMENT FROM FIELD TO WATERSHED

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies have demonstrated some phosphorus (P) loss reduction following implementation of remedial strategies at field scales. However, there has been little coordinated evaluation of Best Management Practices (BMPs) on a watershed scale to show where, when, and which work most effectively. Thus, i...

  3. Evaluation of the Magnetic Fields and Mutual Inductance between Circular Coils Arbitrarily Positioned in Space

    NASA Astrophysics Data System (ADS)

    Anele, A. O.; Hamam, Y.; Chassagne, L.; Linares, J.; Alayli, Y.; Djouani, K.

    2015-09-01

    This paper presents the evaluation of the magnetic fields and mutual inductance between circular coils arbitrarily positioned in space. Firstly, based on an advanced and relevant model available in the literature, MATLAB code is implemented to evaluate the mutual inductance between circular coils arbitrarily positioned with respect to each other. The computed results are compared with the numerical results previously published in the literature and a detailed clarification regarding the huge computational errors made are presented. In the second part, a complex and relevant model available in the literature for evaluating the magnetic fields due to a circular coil is presented. Based on the useful information, the model for computing the magnetic fields between two circular coils is formulated. The computed results are validated with experimental measurements. The comparison of the results shows that the developed model and the experimental measurements conducted are accurate and effective.

  4. Performance evaluation of infrared imaging system in field test

    NASA Astrophysics Data System (ADS)

    Wang, Chensheng; Guo, Xiaodong; Ren, Tingting; Zhang, Zhi-jie

    2014-11-01

    Infrared imaging system has been applied widely in both military and civilian fields. Since the infrared imager has various types and different parameters, for system manufacturers and customers, there is great demand for evaluating the performance of IR imaging systems with a standard tool or platform. Since the first generation IR imager was developed, the standard method to assess the performance has been the MRTD or related improved methods which are not perfect adaptable for current linear scanning imager or 2D staring imager based on FPA detector. For this problem, this paper describes an evaluation method based on the triangular orientation discrimination metric which is considered as the effective and emerging method to evaluate the synthesis performance of EO system. To realize the evaluation in field test, an experiment instrument is developed. And considering the importance of operational environment, the field test is carried in practical atmospheric environment. The test imagers include panoramic imaging system and staring imaging systems with different optics and detectors parameters (both cooled and uncooled). After showing the instrument and experiment setup, the experiment results are shown. The target range performance is analyzed and discussed. In data analysis part, the article gives the range prediction values obtained from TOD method, MRTD method and practical experiment, and shows the analysis and results discussion. The experimental results prove the effectiveness of this evaluation tool, and it can be taken as a platform to give the uniform performance prediction reference.

  5. On evaluation of nonplanar diagrams in noncommutative field theory

    NASA Astrophysics Data System (ADS)

    Liao, Yi

    2005-05-01

    This is a technical work about how to evaluate loop integrals appearing in one loop nonplanar (NP) diagrams in noncommutative (NC) field theory. The conventional wisdom says that, barring the ultraviolet/infrared (UV/IR) mixing problem, NP diagrams whose planar counterparts are UV divergent are rendered finite by NC phases that couple the loop momentum to the external ones p through an NC momentum ρ=θp. We show that this is generally not the case. We find that subtleties arise already in the simpler case of Euclidean spacetime. The situation is even worse in Minkowski spacetime due to its indefinite metric. We compare different prescriptions that may be used to evaluate loop integrals in ordinary theory. They are equivalent in the sense that they always yield identical results. However, in NC theory there is no a priori reason that these prescriptions, except for the defining one that is built in the Feynman propagator, are physically justified even when they seem mathematically meaningful. Employing them can lead to ambiguous results, which are also different from those obtained according to the defining prescription. For ρ>0, the NC phase can worsen the UV property of loop integrals instead of always improving it in high dimensions. We explain how this surprising phenomenon comes about from the indefinite metric. This lends a strong support to the point of view that the naive approach is not well-founded when time does not commute with space. For ρ<0, the NC phase improves the UV property and softens the quadratic UV divergence in ordinary theory to a bounded but indefinite UV oscillation. We employ a cut-off method to quantify the new UV nonregular terms. For ρ>0, these terms are generally complex and thus also harm unitarity in addition to those found previously. As the new terms for both cases are not available in the Lagrangian and in addition can be non-Hermitian when time does not commute with space, our result casts doubts on previous demonstrations

  6. Field Artillery Ammunition Processing System (FAAPS) concept evaluation study

    SciTech Connect

    Kring, C.T.; Babcock, S.M.; Watkin, D.C.; Oliver, R.P.

    1992-06-01

    The Field Artillery Ammunition Processing System (FAAPS) is an initiative to introduce a palletized load system (PLS) that is transportable with an automated ammunition processing and storage system for use on the battlefield. System proponents have targeted a 20% increase in the ammunition processing rate over the current operation while simultaneously reducing the total number of assigned field artillery battalion personnel by 30. The overall objective of the FAAPS Project is the development and demonstration of an improved process to accomplish these goals. The initial phase of the FAAPS Project and the subject of this study is the FAAPS concept evaluation. The concept evaluation consists of (1) identifying assumptions and requirements, (2) documenting the process flow, (3) identifying and evaluating technologies available to accomplish the necessary ammunition processing and storage operations, and (4) presenting alternative concepts with associated costs, processing rates, and manpower requirements for accomplishing the operation. This study provides insight into the achievability of the desired objectives.

  7. Transmitted sound field due to an impulsive line acoustic source bounded by a plate followed by a vortex sheet

    NASA Technical Reports Server (NTRS)

    Miura, T.; Chao, C. C.

    1980-01-01

    The propagation of sound due to a line acoustic source in the moving stream across a semiinfinite vortex sheet which trails from a rigid plate is examined in a linear theory for the subsonic case. A solution for the transmitted sound field is obtained with the aid of multiple integral transforms and the Wiener-Hopf technique for both the steady state (time harmonic) and initial value (impulsive source) situations. The contour of inverse transform and hence the decomposition of the functions are determined through causality and radiation conditions. The solution obtained satisfies causality and the full Kutta conditions. The transmitted sound field is composed of two waves in both the stady state and initial value problems. One is the wave scattered from the edge of the plate which is associated with the bow wave and the instability wave. These waves exist in the downstream sectors. The other is the wave transmitted through the vortex sheet which is also associated with the instability wave. Regional divisions of the transmitted sound field are identified.

  8. Failure of Femoral Access to Electrophysiological Evaluation Due to Aplasia of the Inferior Vena Cava

    PubMed Central

    Parahuleva, Mariana S.; Burgazli, Mehmet; Soydan, Nedim; Franzen, Wolfgang; Güttler, Norbert; Erdogan, Ali

    2016-01-01

    We report an interesting case of a man with a persistent left superior vena cava (PLSVC) with left azygos vein who underwent electrophysiological evaluation. Further evaluation revealed congenital dilated azygos vein, while a segment connecting the inferior vena cava (IVC) to the hepatic vein and right atrium was missing. The azygos vein drained into the superior vena cava, and the hepatic veins drained directly into the right atrium. The patient did not have congenital anomalies of the remaining thoracoabdominal vasculature. PMID:27257399

  9. Effects of plasmonic field due to gold nanoparticles and magnetic field on photocurrents of zinc porphyrin-viologen linked compound-gold nanoparticle composite films

    NASA Astrophysics Data System (ADS)

    Yonemura, Hiroaki; Niimi, Tomoki; Yamada, Sunao

    2016-03-01

    Composite films of zinc-porphyrin-viologen (ZnP-V2+) linked compound containing six methylene group [ZnP(6)V]-gold nanoparticles (AuNP) were fabricated by combining electrostatic layer-by-layer adsorption and the Langmuir-Blodgett method. The anodic photocurrents of the ZnP(6)V-AuNP composite films are higher than those of the ZnP(6)V films. The large photocurrents in ZnP(6)V-AuNP composite films are most likely attributable to the combination of localized surface plasmon resonance due to AuNP and photoinduced intramolecular electron transfer from excited state of ZnP to V2+. The photocurrents of the ZnP(6)V-AuNP composite films increase in the presence of magnetic field. The photocurrents increase with low magnetic fields (B ≤ 150 mT) and are almost constant under high magnetic fields (B ≥ 150 mT). Magnetic field effects (MFEs) were clearly observed for both ZnP(6)V-AuNP composite films and ZnP(6)V films. The MFEs can be explained by a radical pair mechanism.

  10. Seismic fragility analysis of typical pre-1990 bridges due to near- and far-field ground motions

    NASA Astrophysics Data System (ADS)

    Mosleh, Araliya; Razzaghi, Mehran S.; Jara, José; Varum, Humberto

    2016-03-01

    Bridge damages during the past earthquakes caused several physical and economic impacts to transportation systems. Many of the existing bridges in earthquake prone areas are pre-1990 bridges and were designed with out of date regulation codes. The occurrences of strong motions in different parts of the world show every year the vulnerability of these structures. Nonlinear dynamic time history analyses were conducted to assess the seismic vulnerability of typical pre-1990 bridges. A family of existing concrete bridge representative of the most common bridges in the highway system in Iran is studied. The seismic demand consists in a set of far-field and near-field strong motions to evaluate the likelihood of exceeding the seismic capacity of the mentioned bridges. The peak ground accelerations (PGAs) were scaled and applied incrementally to the 3D models to evaluate the seismic performance of the bridges. The superstructure was assumed to remain elastic and the nonlinear behavior in piers was modeled by assigning plastic hinges in columns. In this study the displacement ductility and the PGA are selected as a seismic performance indicator and intensity measure, respectively. The results show that pre-1990 bridges subjected to near-fault ground motions reach minor and moderate damage states.

  11. Evanescent Field Based Photoacoustics: Optical Property Evaluation at Surfaces.

    PubMed

    Goldschmidt, Benjamin S; Rudy, Anna M; Nowak, Charissa A; Tsay, Yowting; Whiteside, Paul J D; Hunt, Heather K

    2016-01-01

    Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. Optical property evaluation of thin films and the surfaces of bulk materials is an important step in understanding new optical material systems and their applications. The method presented can estimate thickness, refractive index, and use absorptive properties of materials for detection. This metrology system uses evanescent field-based photoacoustics (EFPA), a field of research based upon the interaction of an evanescent field with the photoacoustic effect. This interaction and its resulting family of techniques allow the technique to probe optical properties within a few hundred nanometers of the sample surface. This optical near field allows for the highly accurate estimation of material properties on the same scale as the field itself such as refractive index and film thickness. With the use of EFPA and its sub techniques such as total internal reflection photoacoustic spectroscopy (TIRPAS) and optical tunneling photoacoustic spectroscopy (OTPAS), it is possible to evaluate a material at the nanoscale in a consolidated instrument without the need for many instruments and experiments that may be cost prohibitive. PMID:27500652

  12. Field evaluation of ventilation system performance in enclosed parking garages

    SciTech Connect

    Ayari, A.M.; Grot, D.A.; Krarti, M.

    2000-07-01

    This paper summarizes the results of a field study to determine the ventilation requirements and the contaminant levels in existing enclosed parking garages. The testing was conducted in seven parking garages with different sizes, traffic flow patterns, vehicle types, and locations. In particular, the study compares the actual ventilation rates measured using the tracer gas technique with the ventilation requirements of ANSI/ASHRAE Standard 62-1989. In addition, the field test evaluated the effectiveness of the existing ventilation systems in maintaining acceptable contaminant levels within enclosed parking garages.

  13. Evaluation of Rotordynamic Stability of a Steam Turbine Due to Labyrinth Seal Force

    NASA Astrophysics Data System (ADS)

    Hirano, Toshio; Sasaki, Takashi; Sakakida, Hitoshi; Uchida, Tatsuro; Tsutsui, Masaji; Ikeda, Kazunori

    This paper describes the evaluation of unstable vibration caused by the seal force, which is known as "Steam Whirl" in a steam turbine. Stability of a steam turbine is evaluated by complex eigenvalue analysis of rotordynamics model considering the dynamics of seals, rotor, bearings and pedestals. A commercial CFD program is employed to estimate the dynamic coefficients of labyrinth seal. The labyrinth seal of a large scales steam turbine is taken as an object of analysis and a 3D model with eccentric rotor is solved to obtain the rotordynamic force components. The rotordynamic force is derived by integrating the pressure on the rotor surface. Evaluation formula is formed from the results of numerical calculation, which is used to predict the dynamic coefficient of each seal in a steam turbine. Then rotordynamics model of total system including seal is constructed and stability is evaluated by complex eigenvalue analysis. This procedure is applied to the design of steam turbines and enables the optimization of the turbine structure considering the efficiency and stability.

  14. Spatiotemporal splitting of global eigenmodes due to cross-field coupling via vortex dynamics in drift wave turbulence.

    PubMed

    Brandt, C; Thakur, S C; Light, A D; Negrete, J; Tynan, G R

    2014-12-31

    Spatiotemporal splitting events of drift wave (DW) eigenmodes due to nonlinear coupling are investigated in a cylindrical helicon plasma device. DW eigenmodes in the radial-azimuthal cross section have been experimentally observed to split at radial locations and recombine into the global eigenmode with a time shorter than the typical DW period (t≪fDW(-1)). The number of splits correlates with the increase of turbulence. The observed dynamics can be theoretically reproduced by a Kuramoto-type model of a network of radially coupled azimuthal eigenmodes. Coupling by E×B-vortex convection cell dynamics and ion gyro radii motion leads to cross-field synchronization and occasional mode splitting events. PMID:25615346

  15. Quantum corrections to the gravitational potentials of a point source due to conformal fields in de Sitter

    NASA Astrophysics Data System (ADS)

    Fröb, Markus B.; Verdaguer, Enric

    2016-03-01

    We derive the leading quantum corrections to the gravitational potentials in a de Sitter background, due to the vacuum polarization from loops of conformal fields. Our results are valid for arbitrary conformal theories, even strongly interacting ones, and are expressed using the coefficients b and b' appearing in the trace anomaly. Apart from the de Sitter generalization of the known flat-space results, we find two additional contributions: one which depends on the finite coefficients of terms quadratic in the curvature appearing in the renormalized effective action, and one which grows logarithmically with physical distance. While the first contribution corresponds to a rescaling of the effective mass, the second contribution leads to a faster fall-off of the Newton potential at large distances, and is potentially measurable.

  16. Pulmonary Hypertension Due to Common Respiratory Conditions: Classification, Evaluation and Management Strategies.

    PubMed

    Fein, Daniel G; Zaidi, Ali N; Sulica, Roxana

    2016-01-01

    Pulmonary hypertension (PH) due to chronic respiratory disease and/or hypoxia is classified as World Health Organization (WHO) Group III pulmonary hypertension. The patients most commonly encountered in clinical practice with group III PH include those with chronic obstructive lung disease (COPD), diffuse parenchymal lung disease, and sleep-disordered breathing. The purpose of this review is to outline the variable clinical significance of pulmonary hypertension in the most common pulmonary disease states and how a clinician may approach the management of these patients. PMID:27571110

  17. Enhanced Valley Zeeman Splitting in MoS2 /EuS due to interfacial exchange field

    NASA Astrophysics Data System (ADS)

    Zhao, Chuan; Scrace, Thomas; Taheri, Payam; Zhang, Peiyao; Norden, Tenzin; Blizzard, Brett; Petrou, Athos; Zeng, Hao; Zhao, Puqin; Kioseoglou, George

    A monolayer transition metal dichalcogenides such as MoS2 with broken inversion symmetry possesses two degenerate yet inequivalent valleys that can be selectively excited by circularly polarized light. The ability to manipulate valley degrees of freedom with light or external magnetic field makes them attractive for optoelectronic and spintronic applications. On the other hand, it has been demonstrated recently that a magnetic insulator such as EuS can induce magnetic exchange field (MEF) on graphene through proximity effect. Thus, construction of a magnetic insulator/TMDC heterostructure may induce large MEF on TMDC, which may lead to giant valley Zeeman splitting. In this work, we report the observation of valley Zeeman splitting in monolayer MoS2 and other TMDCs due to the MEF from EuS substrates. Using magneto-reflectivity, we measured a Zeeman splitting of valley exciton of 2 meV at 7 tesla and 4 K, for monolayer MoS2 on a SiO2 substrate. This is consistent with values reported in monolayer WSe2. However, when EuS is used as the substrate, we observed an increase of valley splitting from 2 to 10 meV. We attribute this enhanced valley splitting to the MEF from the EuS substrate. Utilizing MEF of a magnetic insulator can induce magnetic ordering and giant Zeeman splitting in 2D TMDCs, which might enable novel spintronics applications.

  18. A Method for Evaluating Volt-VAR Optimization Field Demonstrations

    SciTech Connect

    Schneider, Kevin P.; Weaver, T. F.

    2014-08-31

    In a regulated business environment a utility must be able to validate that deployed technologies provide quantifiable benefits to the end-use customers. For traditional technologies there are well established procedures for determining what benefits will be derived from the deployment. But for many emerging technologies procedures for determining benefits are less clear and completely absent in some cases. Volt-VAR Optimization is a technology that is being deployed across the nation, but there are still numerous discussions about potential benefits and how they are achieved. This paper will present a method for the evaluation, and quantification of benefits, for field deployments of Volt-VAR Optimization technologies. In addition to the basic methodology, the paper will present a summary of results, and observations, from two separate Volt-VAR Optimization field evaluations using the proposed method.

  19. Evaluation of short-interfering RNAs treatment in experimental rabies due to wild-type virus.

    PubMed

    Appolinario, Camila Michele; Allendorf, Susan Dora; Peres, Marina Gea; Fonseca, Clovis Reynaldo; Vicente, Acacia Ferreira; Antunes, João Marcelo Azevedo de Paula; Pantoja, José Carlos Figueiredo; Megid, Jane

    2015-01-01

    We have evaluated the efficacy of short-interfering RNAs targeting the nucleoprotein gene and also the brain immune response in treated and non-treated infected mice. Mice were inoculated with wild-type virus, classified as dog (hv2) or vampire bat (hv3) variants and both groups were treated or left as controls. No difference was observed in the lethality rate between treated and non-treated groups, although clinical evaluation of hv2 infected mice showed differences in the severity of clinical disease (p=0.0006). Evaluation of brain immune response 5 days post-inoculation in treated hv2 group showed no difference among the analyzed genes, whereas after 10 days post-inoculation there was increased expression of 2',5'-oligoadenylate synthetase 1, tumor necrosis factor alpha, interleukin 12, interferon gamma, and C-X-C motif chemokine 10 associated with higher expression of N gene in the same period (p<0.0001). In hv2 non-treated group only higher interferon beta expression was found at day 5. The observed differences in results of the immune response genes between treated and non-treated groups is not promising as they had neither impact on mortality nor even a reduction in the expression of N gene in siRNA treated animals. This finding suggests that the use of pre-designed siRNA alone may not be useful in rabies treatment. PMID:26254692

  20. Evaluation of asphalt-rubber membrane field performance

    NASA Astrophysics Data System (ADS)

    Shuler, S.; Gallaway, B. M.; Epps, J. A.

    1982-05-01

    This report presents a record of asphalt-rubber membrane field performance in Texas. An evaluation of performance is presented for forty-five separate projects in thirteen state highway districts. Approximately 850 lane miles of highways are represented by materials constructed as stress absorbing membranes (asphalt-rubber seal coats beneath asphalt concrete overlay). All projects reviewed were constructed between June, 1976 and September, 1981.

  1. Field evaluation of a modified intervention for overhead drilling.

    PubMed

    Rempel, David; Star, Demetra; Barr, Alan; Blanco, Marco Mendoza; Janowitz, Ira

    2010-04-01

    Drilling holes into concrete or metal ceilings is one of the most physically demanding tasks performed in construction. The work is done overhead with rotary impact hammer drills that weigh up to 40 N. The task is associated with pain and musculoskeletal disorders at the wrist, forearm, shoulder, and back. The mechanism of injury is thought to be the high forces and non-neutral shoulder and wrist postures applied during drilling. Previously, we described a field study of a foot lever and inverted drill press intervention devices that received poor usability ratings compared with the usual method for overhead drilling based on problems with mobility and productivity. Using a participatory intervention model, feedback from construction workers (N = 13) was used to develop a new intervention design that incorporated a wheeled tripod base and a unique method of aligning the drilling column to vertical. A different group of construction workers (N = 23) evaluated usability and fatigue of the new device during their regular overhead drilling in comparison with the usual method. Four of 12 usability ratings were significantly better with the intervention device compared with the usual method. Subjective shoulder fatigue was less with the new intervention (1.1 vs. 3.3; scale 0 to 5; p < 0.001). This difference was supported by objective outcome measures; the mean hand forces during drilling were 26 N with the intervention compared with 245 N with the usual method. The percentage of time with the shoulder flexed or abducted to more than 60 degrees was less with the intervention compared with the usual method (21 vs. 40%; p = 0.007). There was significantly less head extension with the intervention compared with the usual method. There were no significant differences in overall productivity between the two methods. This study demonstrates that a new intervention device for overhead drilling has improved usability and subjective fatigue ratings compared with the usual method

  2. Evaluating Field Spectrometer Performance with Transmission Standards: Examples from the USGS Spectral Library and Research Databases

    NASA Astrophysics Data System (ADS)

    Hoefen, T. M.; Kokaly, R. F.; Swayze, G. A.; Livo, K. E.

    2015-12-01

    Collection of spectroscopic data has expanded with the development of field-portable spectrometers. The most commonly available spectrometers span one or several wavelength ranges: the visible (VIS) and near-infrared (NIR) region from approximately 400 to 1000 nm, and the shortwave infrared (SWIR) region from approximately 1000-2500 nm. Basic characteristics of spectrometer performance are the wavelength position and bandpass of each channel. Bandpass can vary across the wavelength coverage of an instrument, due to spectrometer design and detector materials. Spectrometer specifications can differ from one instrument to the next for a given model and between manufacturers. The USGS Spectroscopy Lab in Denver has developed a simple method to evaluate field spectrometer wavelength accuracy and bandpass values using transmission measurements of materials with intense, narrow absorption features, including Mylar* plastic, praseodymium-doped glass, and National Institute of Standards and Technology Standard Reference Material 2035. The evaluation procedure has been applied in laboratory and field settings for 19 years and used to detect deviations from cited manufacturer specifications. Tracking of USGS spectrometers with transmission standards has revealed several instances of wavelength shifts due to wear in spectrometer components. Since shifts in channel wavelengths and differences in bandpass between instruments can impact the use of field spectrometer data to calibrate and analyze imaging spectrometer data, field protocols to measure wavelength standards can limit data loss due to spectrometer degradation. In this paper, the evaluation procedure will be described and examples of observed wavelength shifts during a spectrometer field season will be presented. The impact of changing wavelength and bandpass characteristics on spectral measurements will be demonstrated and implications for spectral libraries will be discussed. *Any use of trade, firm, or product names

  3. Permeability enhancement due to cold water injection: A Case Study at the Los Azufres Geothermal Field, Mexico

    SciTech Connect

    Benson, S.M.; Daggett, J.; Ortiz, J.; Iglesias, E.; Comision Federal de Electricidad, Morelia; Instituto de Investigaciones Electricas, Cuernavaca )

    1989-04-01

    Pressure transient buildup and falloff data from 3 wells at the Los Azufres geothermal field have been evaluated to determine the extent to which cold water infection increases the permeability of the near-bore reservoir formation. Simultaneous analysis of the buildup and falloff data provides estimates of the permeability-thickness of the reservoir, the skin factor of the well, and the degree of permeability enhancement in the region behind the thermal front. Estimates of permeability enhancement range from a factor of 4 to 9, for a temperature change of about 150{degree}C. The permeability enhancement is attributed to thermally induced contraction and stress-cracking of the formation. 9 refs., 18 figs.

  4. Evaluation of physical health effects due to volcanic hazards: human studies

    SciTech Connect

    Buist, A.S.; Bernstein, R.S.; Johnson, L.R.; Vollmer, W.M.

    1986-03-01

    Despite certain gaps in the knowledge that has been gained from the studies done in the aftermath of Mount St. Helens and following previous major volcanic eruptions, we can be confident that the health effects of both short- and long-term exposures to the relatively low levels of airborne volcanic ash that are typical following such a volcanic eruption are minor. These effects seem to relate more to the irritating effect of the ash on mucous membranes and airway epithelia than to the potential of the ash (due to its free crystalline silica content) to initiate a fibrotic response. Nevertheless, common sense dictates that exposures should be minimized whenever possible by use of appropriate preventive measures, such as wetting the sedimented ash before disturbing it, and using commercially available disposable paper masks meeting NIOSH code TC-23 for dusts for light exposures and industrial half- and full-faced respirator and goggles for more extensive and heavy exposure.

  5. Evaluations of effects due to low-frequency noise in a low demanding work situation

    NASA Astrophysics Data System (ADS)

    Bengtsson, J.; Persson Waye, K.; Kjellberg, A.

    2004-11-01

    Noise sources with a dominating content of low frequencies (20-200 Hz) are found in many occupational environments. This study aimed to evaluate effects of moderate levels of low-frequency noise on attention, tiredness and motivation in a low demanding work situation. Two ventilation noises at the same A-weighted sound pressure level of 45 dB were used: one of a low-frequency character and one of a flat frequency character (reference noise). Thirty-eight female subjects worked with six performance tasks for 4 h in the noises in a between-subject design. Most of the tasks were monotonous and routine in character. Subjective reports were collected using questionnaires and cortisol levels were measured in saliva. The major finding in this study was that low-frequency noise negatively influenced performance on two tasks sensitive to reduced attention and on a proof-reading task. Performances of tasks aimed at evaluating motivation were not significantly affected. The difference in work performance was not reflected by the subjective reports. No effect of noise was found on subjective stress or cortisol levels.

  6. Severe metabolic alkalosis due to pyloric obstruction: case presentation, evaluation, and management.

    PubMed

    McCauley, Meredith; Gunawardane, Manjula; Cowan, Mark J

    2006-12-01

    A 46-year-old man presented to the emergency room with severe metabolic alkalosis, hypokalemia, and respiratory failure requiring intubation and mechanical ventilation. The cause of his acid-base disorder was initially unclear. Although alkalosis is common in the intensive care unit, metabolic alkalosis of this severity is unusual, carries a very high mortality rate, and requires careful attention to the pathophysiology and differential diagnosis to effectively evaluate and treat the patient. A central concept in the diagnosis of metabolic alkalosis is distinguishing chloride responsive and chloride nonresponsive states. Further studies are then guided by the history and physical examination in most cases. By using a systematic approach to the differential diagnosis, we were able to determine that a high-grade gastric outlet obstruction was the cause of the patients' alkalosis and to offer effective therapy for his condition. A literature review and algorithm for the diagnosis and management of metabolic alkalosis are also presented. PMID:17170625

  7. Dynamic evaluation of environmental impact due to tritium accidental release from the fusion reactor.

    PubMed

    Nie, Baojie; Ni, Muyi; Jiang, Jieqiong; Wu, Yican

    2015-10-01

    As one of the key safety issues of fusion reactors, tritium environmental impact of fusion accidents has attracted great attention. In this work, the dynamic tritium concentrations in the air and human body were evaluated on the time scale based on accidental release scenarios under the extreme environmental conditions. The radiation dose through various exposure pathways was assessed to find out the potential relationships among them. Based on this work, the limits of HT and HTO release amount for arbitrary accidents were proposed for the fusion reactor according to dose limit of ITER. The dynamic results aim to give practical guidance for establishment of fusion emergency standard and design of fusion tritium system. PMID:26164282

  8. Evaluation of Astrometry Errors due to the Optical Surface Distortions in Adaptive Optics Systems and Science Instruments

    NASA Astrophysics Data System (ADS)

    Ellerbroek, Brent; Herriot, Glen; Suzuki, Ryuji; Matthias, Schoeck

    2013-12-01

    The objectives for high precision astrometry on ELTs will be challenging, with requirements in the range from 10 to 50 micro-arc-seconds for some instruments and science cases. Reducing and correctly calibrating the systematic and quasi-static errors introduced by optical surface distortions will be an important part of meeting these goals. In a recently submitted paper, we described an analytical Fourier domain model for evaluating these effects as the sum of three terms: (i) under-sampling errors, due to measuring the effects of static surface distortions using a finite number of discrete reference sources; (ii) unknown beam wander across the static surface distortions due to line-of-sight jitter or boresighting errors, and (iii) quasi-static errors due to slowly varying surface distortions. In this paper, we apply these methods to evaluating this term in the astrometry error budgets for the TMT Infrared Imaging Spectrograph (IRIS) and the facility AO system, NFIRAOS. The inputs to this exercise include the original top-down allocations for this error term, the original optical surface specifications for IRIS and NFIRAOS as derived earlier on the basis of wavefront error requirements, our assessment of the feasible density and positioning accuracy for an array of calibration sources, and the expected beam wander due to tip/tilt jitter and bore-sighting errors between NFIRAOS and IRIS. The astrometry error computed for these initial parameters was considerably larger than the top-down allocation due to the contributions from the NFIRAOS double-pane entrance window, which is close to the system's input focal plane. The error can be reduced to fall within the allocation by defining tighter, but still feasible, specifications for these elements. We also evaluated the astrometry errors due to quasi-static drift of the figures of the NFIRAOS deformable mirrors, and determined that they are acceptable for RMS wavefront distortions of up to about 30 nm RMS.

  9. Field tests for evaluating the aerobic work capacity of firefighters.

    PubMed

    Lindberg, Ann-Sofie; Oksa, Juha; Gavhed, Désirée; Malm, Christer

    2013-01-01

    Working as a firefighter is physically strenuous, and a high level of physical fitness increases a firefighter's ability to cope with the physical stress of their profession. Direct measurements of aerobic capacity, however, are often complicated, time consuming, and expensive. The first aim of the present study was to evaluate the correlations between direct (laboratory) and indirect (field) aerobic capacity tests with common and physically demanding firefighting tasks. The second aim was to give recommendations as to which field tests may be the most useful for evaluating firefighters' aerobic work capacity. A total of 38 subjects (26 men and 12 women) were included. Two aerobic capacity tests, six field tests, and seven firefighting tasks were performed. Lactate threshold and onset of blood lactate accumulation were found to be correlated to the performance of one work task (r(s) = -0.65 and -0.63, p<0.01, respectively). Absolute (mL · min(-1)) and relative (mL · kg(-1) · min(-1)) maximal aerobic capacity was correlated to all but one of the work tasks (r(s) = -0.79 to 0.55 and -0.74 to 0.47, p<0.01, respectively). Aerobic capacity is important for firefighters' work performance, and we have concluded that the time to row 500 m, the time to run 3000 m relative to body weight (s · kg(-1)), and the percent of maximal heart rate achieved during treadmill walking are the most valid field tests for evaluating a firefighter's aerobic work capacity. PMID:23844153

  10. Molecular Evaluation of a Case of Visceral Leishmaniasis Due to Leishmania tropica in Southwestern Iran

    PubMed Central

    SARKARI, Bahador; BAVARSAD AHMADPOUR, Niloofar; MOSHFE, Abdolali; HAJJARAN, Homa

    2016-01-01

    We describe a case of visceral leishmaniasis (VL) due to Leishmania tropica in a 50-year-old Iranian man lived in a VL-endemic area in southwest of Iran. The patient presented with a 3-month history of fever and splenomegaly. Clinical signs and serological findings were suggestive of VL. Spleen biopsy was taken from the patient and intracellular forms of Leishmania amastigotes was seen in Giemsa stained smears. The patient was treated with pentavalent antimonial compound with complete resolution of his systemic signs and symptoms. DNA was extracted from the microscopic slides of the spleen biopsy and the nagt (N-Acetylglucosamine-1-Phosphate Transferase) gene of Leishmania was PCR-amplified. Sequence analysis of the PCR product demonstrated that the case has 99% identity with those of available sequences of L. tropica. Intra-species variation within isolate was 0–0.1%; whereas, inter-species differences of the isolate with those of L. major and L. infantum was significantly higher. PMID:27095980

  11. Laboratory or field tests for evaluating firefighters' work capacity?

    PubMed

    Lindberg, Ann-Sofie; Oksa, Juha; Malm, Christer

    2014-01-01

    Muscle strength is important for firefighters work capacity. Laboratory tests used for measurements of muscle strength, however, are complicated, expensive and time consuming. The aims of the present study were to investigate correlations between physical capacity within commonly occurring and physically demanding firefighting work tasks and both laboratory and field tests in full time (N = 8) and part-time (N = 10) male firefighters and civilian men (N = 8) and women (N = 12), and also to give recommendations as to which field tests might be useful for evaluating firefighters' physical work capacity. Laboratory tests of isokinetic maximal (IM) and endurance (IE) muscle power and dynamic balance, field tests including maximal and endurance muscle performance, and simulated firefighting work tasks were performed. Correlations with work capacity were analyzed with Spearman's rank correlation coefficient (rs). The highest significant (p<0.01) correlations with laboratory and field tests were for Cutting: IE trunk extension (rs = 0.72) and maximal hand grip strength (rs = 0.67), for Stairs: IE shoulder flexion (rs = -0.81) and barbell shoulder press (rs = -0.77), for Pulling: IE shoulder extension (rs = -0.82) and bench press (rs = -0.85), for Demolition: IE knee extension (rs = 0.75) and bench press (rs = 0.83), for Rescue: IE shoulder flexion (rs = -0.83) and bench press (rs = -0.82), and for the Terrain work task: IE trunk flexion (rs = -0.58) and upright barbell row (rs = -0.70). In conclusion, field tests may be used instead of laboratory tests. Maximal hand grip strength, bench press, chin ups, dips, upright barbell row, standing broad jump, and barbell shoulder press were strongly correlated (rs≥0.7) with work capacity and are therefore recommended for evaluating firefighters work capacity. PMID:24614596

  12. FDTD analysis of temperature elevation in the lens of human and rabbit models due to near-field and far-field exposures at 2.45 GHz.

    PubMed

    Oizumi, Takuya; Laakso, Ilkka; Hirata, Akimasa; Fujiwara, Osamu; Watanabe, Soichi; Taki, Masao; Kojima, Masami; Sasaki, Hiroshi; Sasaki, Kazuyuki

    2013-07-01

    The eye is said to be one of the most sensitive organs to microwave heating. According to previous studies, the possibility of microwave-induced cataract formation has been experimentally investigated in rabbit and monkey eyes, but not for the human eye due to ethical reasons. In the present study, the temperature elevation in the lens, the skin around the eye and the core temperature of numerical human and rabbit models for far-field and near-field exposures at 2.45 GHz are investigated. The temperature elevations in the human and rabbit models were compared with the threshold temperatures for inducing cataracts, thermal pain in the skin and reversible health effects such as heat exhaustion or heat stroke. For plane-wave exposure, the core temperature elevation is shown to be essential both in the human and in the rabbit models as suggested in the international guidelines and standards. For localised exposure of the human eye, the temperature elevation of the skin was essential, and the lens temperature did not reach its threshold for thermal pain. On the other hand, the lens temperature elevation was found to be dominant for the rabbit eye. PMID:23390146

  13. Evaluation of the tapered PMMA fiber sensor response due to the ionic interaction within electrolytic solutions

    NASA Astrophysics Data System (ADS)

    Batumalay, M.; Rahman, H. A.; Kam, W.; Ong, Y. S.; Ahmad, F.; Zakaria, R.; Harun, S. W.; Ahmad, H.

    2014-01-01

    A tapered plastic multimode fiber (PMMA) optical sensor is proposed and demonstrated for continuous monitoring of solutions based on different concentration of sodium chloride and glucose in deionized water The tapered PMMA fiber was fabricated using an etching method involving deionized water and acetone to achieve a waist diameter and length of 0.45 mm and 10 mm, respectively, and was used to investigate the effect of straight, U-shape, and knot shape against concentration for both sodium chloride and glucose. The results show that there is a strong dependence of the electrolytic and non-electrolytic nature of the chemical solutions on the sensor output. It is found that the sensitivity of the sodium chloride concentration sensor with the straight tapered fiber probe was 0.0023 mV/%, which was better than the other probe arrangements of U-shape and knot. Meanwhile, the glucose sensor performs with the highest sensitivity of 0.0026 mV/wt % with the knot-shaped tapered fiber probe. In addition, a tapered PMMA probe which was coated by silver film was fabricated and demonstrated using calcium hypochlorite (G70) solution. The working mechanism of such a device is based on the observed increment in the transmission of the sensor that is immersed in solutions of higher concentration. As the concentration varies from 0 ppm to 6 ppm, the output voltage of the sensor increases linearly from 3.61 mV to 4.28 mV with a sensitivity of 0.1154 mV/ppm and a linearity of more than 99.47%. The silver film coating increases the sensitivity of the proposed sensor due to the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber.

  14. Evaluation of the uncertainty due to land cover observation and conversion into plant functional types

    NASA Astrophysics Data System (ADS)

    Georgievski, Goran; Hartley, Andrew; MacBean, Natasha; Hagemann, Stefan

    2016-04-01

    Land surface processes represented in the latest generation of climate models (IPCC AR5) use the concept of Plant Functional Types (PFTs) to group different vegetation types and species according to similar physiological, biochemical and structural characteristics. The 5th IPCC Assessment Report recognizes the role of the Land Surface Models (LSMs) as one of the key contributors to uncertainty in climate change impacts projections. In the frame of the European Space Agency (ESA) Climate Change Initiative (CCI), a new global land cover (LC) data set was derived. We aim to investigate two sources of uncertainties in LSMs and their ranges: (i) uncertainty of ESA-CCI state of the art satellite observation of LC classes, and (ii) uncertainty due to LC conversion ("cross-walking (CW) procedure") into PFTs. Therefore, we have derived 5 perturbations of PFTs maps: (i) reference map (REF), (ii) map that minimizes biomass in LC observation and CW procedure (MinLC MinCW), (iii) map that minimizes biomass in LC observation with reference CW procedure (MinLC RefCW), (iv) map that maximizes biomass in LC observation with reference CW procedure (MaxLC RefCW), and (v) map that maximizes biomass in LC observation and CW procedure (MaxLC MaxCW). Our analysis demonstrates that there is still considerable uncertainty in the methods used to convert LC classes into the PFTs used by LSMs. Furthermore, uncertainty in the labelling of LC classes has an equal magnitude compared to the cross-walking uncertainty. In the next phase, we aim to quantify the sensitivity of the carbon, hydrological and energy cycles to LC and CW uncertainty with 3 LSMs (JSBACH, JULES, and ORHCIDEE). This work will enable us to both advice the land cover mapping community about the accuracy requirements for land cover maps, and to provide insights to the earth system modelling community on the implications of decisions taken when converting from land cover classes to PFTs.

  15. Evaluation of dermal and eye irritation and skin sensitization due to carbon nanotubes.

    PubMed

    Ema, Makoto; Matsuda, Akitaka; Kobayashi, Norihiro; Naya, Masato; Nakanishi, Junko

    2011-12-01

    The present paper summarizes the results of our studies on dermal and eye irritation and skin sensitization due to carbon nanotubes (CNTs), whose potential applications and uses are wide and varied, including CNT-enhanced plastics, electromagnetic interference/radio-frequency (EMI/RFI) shielding, antistatic material, flexible fibers and advanced polymers, medical and health applications, and scanning probe microscopy. Skin and eyes have the highest risk of exposure to nanomaterials, because deposition of nanomaterials to the surficial organs has the potential to be a major route of exposure during the manufacturing, use, and disposal of nanomaterials. Two products composed of single-walled carbon nanotubes (SWCNTs) and two products composed of multi-walled carbon nanotubes (MWCNTs) were tested regarding acute dermal and acute eye irritation using rabbits, and skin sensitization using guinea pigs. The concentrations of the CNTs in the substances were the maximum allowable for administration. The two products of SWCNTs and one of the products of MWCNTs were not irritants to the skin or eyes. The other product of MWCNTs caused very slight erythema at 24h, but not at 72h, after patch removal in the dermal irritation experiments and conjunctival redness and blood vessel hyperemia at 1h, but not at 24h, in eye irritation experiments. These findings showed that one product of MWCNTs was a very weak acute irritant to the skin and eyes. No products of SWCNTs and MWCNTs exhibited skin-sensitization effects. Our knowledge of the toxicological effects of CNTs is still limited. Further information is needed to clarify the potential for irritation and sensitization given the complex nature of CNTs. PMID:21893152

  16. Cinephotogrammetric Evaluation Of Thoracic Deformation Due To Safety Belt Action During A Crash Test

    NASA Astrophysics Data System (ADS)

    Verriest, J. P.

    1983-07-01

    In order to estimate the thoracic injury tolerance of a belted automobile occupant and to get a better knowledge about the mechanical behaviour of the belt/torso system, the dynamic deformation of the thorax is evaluated under the action of a safety belt load. Therefore, during the whole duration of a crash test (about 120 ms) the relative displacement of a set of points drawn on the thorax surface is measured by cinephotogrammetry. Five 16 mm cine-photo cameras (3 fix around the impact area and 2 on board the sled) filming at 500 frames per second permit to cover the whole trunk surface. Synchronization of film data is done by interpolating on a common time base. The three-dimensional coordinates of the measurement points enable the reconstruction of the thorax surface as a set of contiguous triangular plane facets which can be projected on various reference planes for display purposes. For clarity of drawings, an algorithm determines hidden lines not to be plotted. Cuts parallel to the projection plane are performed. By changing the orientation of this plane and the number and the pace of the cuts, either contour maps or transversal cuts are obtained providing a visualization of deformation which can then be related to compressive forces and resulting injuries.

  17. Stochastic Modeling Approach for the Evaluation of Backbreak due to Blasting Operations in Open Pit Mines

    NASA Astrophysics Data System (ADS)

    Sari, Mehmet; Ghasemi, Ebrahim; Ataei, Mohammad

    2014-03-01

    Backbreak is an undesirable side effect of bench blasting operations in open pit mines. A large number of parameters affect backbreak, including controllable parameters (such as blast design parameters and explosive characteristics) and uncontrollable parameters (such as rock and discontinuities properties). The complexity of the backbreak phenomenon and the uncertainty in terms of the impact of various parameters makes its prediction very difficult. The aim of this paper is to determine the suitability of the stochastic modeling approach for the prediction of backbreak and to assess the influence of controllable parameters on the phenomenon. To achieve this, a database containing actual measured backbreak occurrences and the major effective controllable parameters on backbreak (i.e., burden, spacing, stemming length, powder factor, and geometric stiffness ratio) was created from 175 blasting events in the Sungun copper mine, Iran. From this database, first, a new site-specific empirical equation for predicting backbreak was developed using multiple regression analysis. Then, the backbreak phenomenon was simulated by the Monte Carlo (MC) method. The results reveal that stochastic modeling is a good means of modeling and evaluating the effects of the variability of blasting parameters on backbreak. Thus, the developed model is suitable for practical use in the Sungun copper mine. Finally, a sensitivity analysis showed that stemming length is the most important parameter in controlling backbreak.

  18. Evaluation of edge effect due to phase contrast imaging for mammography

    SciTech Connect

    Matsuo, Satoru; Katafuchi, Tetsuro; Tohyama, Keiko; Morishita, Junji; Yamada, Katsuhiko; Fujita, Hiroshi

    2005-08-15

    It is well-known that the edge effect produced by phase contrast imaging results in the edge enhancement of x-ray images and thereby sharpens those images. It has recently been reported that phase contrast imaging using practical x-ray tubes with small focal spots has improved image sharpness as observed in the phase contrast imaging with x-ray from synchrotron radiation or micro-focus x-ray tubes. In this study, we conducted the phase contrast imaging of a plastic fiber and plant seeds using a customized mammography equipment with a 0.1 mm focal spot, and the improvement of image sharpness was evaluated in terms of spatial frequency response of the images. We observed that the image contrast of the plastic fiber was increased by edge enhancement, and, as predicted elsewhere, spectral analysis revealed that as the spatial frequencies of the x-ray images increased, so did the sharpness gained through phase contrast imaging. Thus, phase contrast imaging using a practical molybdenum anode tube with a 0.1 mm-focal spot would benefit mammography, in which the morphological detectability of small species such as micro-calcifications is of great concern. And detectability of tumor-surrounded glandular tissues in dense breast would be also improved by the phase contrast imaging.

  19. Evaluation of Potential pH-Driven Metal Release Due to Elevated Groundwater CO2 Concentrations

    NASA Astrophysics Data System (ADS)

    Tinnacher, R. M.; Varadharajan, C.; Zheng, L.; Spycher, N.; Birkholzer, J. T.; Trautz, R. C.; Pugh, J. D.; Esposito, R.; Nico, P. S.

    2012-12-01

    The injection of carbon dioxide (CO2) emissions from industrial sources into deep geologic formations is a potential option for the control of CO2 concentrations in the atmosphere. While the risk of CO2 migration from the storage reservoir into potable groundwater is low considering the safeguards of site characterization and permitting, it is important to understand what type of potential impacts could occur and how to identify these impacts. Elevated CO2 concentrations may potentially lead to a decrease in groundwater pH and the subsequent release of metals and ions from natural sediments into the groundwater solution. In this risk scenario, potential metal release processes, such as enhanced mineral dissolution, metal desorption and/or ion exchange reactions, may be driven by changes in groundwater pH, the presence of carbonate ligands in solution or a combination of the two. However, a detailed understanding and a distinction of pH-driven and carbonate-driven metal release reactions are important for the development of site monitoring plans and remediation strategies, required by regulations in the unlikely event of a release. Hence, in this study we characterized metal release from natural sediments into synthetic groundwater solutions at two pH conditions in order to mimic the native groundwater pH (pH ~8.5) and the low pH conditions expected in the event of elevated CO2 concentrations (pH~5). In addition, results are compared between tests performed in the presence and absence of elevated CO2. Metal release was investigated in lab-scale sequential leaching experiments using two sediment types with different organic carbon contents over a time-frame of 25 days. Supernatant solutions were monitored for pH and characterized in terms of metal concentrations (ICP-MS), total inorganic carbon (TIC) and anion composition. Furthermore, experimental results were compared with data from a field study involving the controlled release of groundwater containing dissolved

  20. Antibiotic Treatment of Infections Due to Carbapenem-Resistant Enterobacteriaceae: Systematic Evaluation of the Available Evidence

    PubMed Central

    Lourida, Panagiota; Poulikakos, Panagiotis; Rafailidis, Petros I.; Tansarli, Giannoula S.

    2014-01-01

    We sought to evaluate the effectiveness of the antibiotic treatment administered for infections caused by carbapenemase-producing Enterobacteriaceae. The PubMed and Scopus databases were systematically searched. Articles reporting the clinical outcomes of patients infected with carbapenemase-producing Enterobacteriaceae according to the antibiotic treatment administered were eligible. Twenty nonrandomized studies comprising 692 patients who received definitive treatment were included. Almost all studies reported on Klebsiella spp. In 8 studies, the majority of infections were bacteremia, while pneumonia and urinary tract infections were the most common infections in 12 studies. In 10 studies, the majority of patients were critically ill. There are methodological issues, including clinical heterogeneity, that preclude the synthesis of the available evidence using statistical analyses, including meta-analysis. From the descriptive point of view, among patients who received combination treatment, mortality was up to 50% for the tigecycline-gentamicin combination, up to 64% for tigecycline-colistin, and up to 67% for carbapenem-colistin. Among the monotherapy-treated patients, mortality was up to 57% for colistin and up to 80% for tigecycline. Certain regimens were administered to a small number of patients in certain studies. Three studies reporting on 194 critically ill patients with bacteremia showed individually significantly lower mortality in the combination arm than in the monotherapy arm. In the other studies, no significant difference in mortality was recorded between the compared groups. Combination antibiotic treatment may be considered the optimal option for severely ill patients with severe infections. However, well-designed randomized studies of specific patient populations are needed to further clarify this issue. PMID:24080646

  1. DUE PERMAFROST: A Circumpolar Remote Sensing Service for Permafrost - Evaluation Case Studies and Intercomparison with Regional Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Heim, Birgit; Bartsch, Annett; Elger, Kirsten; Rinke, Annette; Klehmet, Katharina; Matthes, Heidrun; Gellhorn, Catrin; Buchhorn, Marcel; Soliman, Aiman; Duguay, Claude

    2013-04-01

    The ESA Data User Element (DUE) Permafrost project provides a Circumpolar remote sensing service for permafrost-related applications. The data products are freely downloadable (http://www.ipf.tuwien.ac.at/permafrost) and published at the PANGAEA World Data Centre (DUE Permafrost Project Consortium, 2012). Remote sensing products are land surface temperature, surface soil moisture, ground frozen/non frozen state, terrain parameters, land cover parameters, and surface waters. Snow parameters (snow extent and snow water equivalent) can be derived from the DUE project GlobSnow (http://www.globsnow.info). The time series of Circumpolar land surface temperature and surface soil moisture offer weekly and monthly averaged data products from 2007 to 2010, Circumpolar ground frozen/non frozen state is provided as daily dataset. The ongoing service will also include the time series of 2011 and 2012. The Circumpolar terrain and land cover products are static, e.g. the first Circumpolar Digital Elevation Model (DEM) north of 55° N with a spatial resolution of 100 m (S. Maurizio & T. Strozzi, 2012). Evaluation is crucial to test the scientific validity of the DUE Permafrost data products for high-latitude permafrost landscapes. The primary programme providing ground data is the Global Terrestrial Network for Permafrost (GTN-P) initiated by the International Permafrost Association (IPA) in the 1990s. The involvement of scientific stakeholders and the IPA, and the ongoing evaluation of the remote sensing derived products make the DUE Permafrost products widely accepted by the scientific community. Evaluation case studies of DUE Permafrost remote-sensing derived products (e.g., land surface temperature and ground frozen/non frozen state) show good agreement with ground data from GTN-P monitoring sites in Alaska and Siberia. The Helmholtz Climate Initiative REKLIM (Regionale Klimaänderungen/Regional climate change) is a climate research program where regional observations and

  2. Dust mobilization due to density currents in the Atlas region: Observations from the Saharan Mineral Dust Experiment 2006 field campaign

    NASA Astrophysics Data System (ADS)

    Knippertz, P.; Deutscher, C.; Kandler, K.; Müller, T.; Schulz, O.; Schütz, L.

    2007-11-01

    Evaporation of precipitation is a ubiquitous feature of dry and hot desert environments. The resulting cooling often generates density currents with strong turbulent winds along their leading edges, which can mobilize large amounts of dust. Mountains support this process by triggering convection, by downslope acceleration of the cool air, and by fostering the accumulation of fine-grained sediments along their foothills through the action of water. For the Sahara, the world's largest dust source, this mechanism has been little studied because of the lack of sufficiently high resolution observational data. The present study demonstrates the frequent occurrence of density currents along the Sahara side of the Atlas Mountain chain in southern Morocco using the unique data set collected during the Saharan Mineral Dust Experiment (SAMUM) field campaign in May/June 2006. The density currents are related to convection over the mountains in the afternoon hours and have lifetimes on the order of 10 h. The passage of the sharp leading edge that sometimes reaches several hundred kilometers in length is usually associated with a marked increase in dew point and wind speed, a change in wind direction, and a decrease in temperature and visibility due to suspended dust. It is conceivable that this mechanism is relevant for other mountainous regions in northern Africa during the warm season. This would imply that simulations of the dust cycle with numerical models need a reliable representation of moist convective processes in order to generate realistic dust emissions from the Sahara.

  3. Experiments evaluating subsidence generated within a subaqueous deformable substrate due to varying differential sediment loading patterns

    NASA Astrophysics Data System (ADS)

    Foreman, B.; Chatmas, E. S.; Abeyta, A.; Paola, C.

    2013-12-01

    The intraslope areas of many passive margins display a complex bathymetry of topographic depressions and crests that form series of minibasins. These minibasins are linked to the deformation of subsurface salt layers and act as localized sediment traps. Many mechanisms have been proposed for the initiation of minibasins, including tectonic forces (both extensional and contractional), regional gravitational sliding, density inversion between salt layers and overburden, and differential sediment loading. Regardless of initiation mechanism, it is widely recognized that synkinematic deposition plays a active role in determining subsidence patterns and sediment routing within and among the minibasins. We undertook a series of simplified 1-D and 2-D experiments 1) to evaluate the feasibility of developing a series of well-defined minibasins created exclusively by differential sediment loading and 2) to quantitatively determine the effects of substrate thickness, density contrast, and sedimentation rate on the resultant subsidence pattern. We also present an initial non-dimensionalized formulation of the problem that relates density contrasts, clinoform thickness, substrate thickness, progradation rate, and viscosity of the deformable substrate. Two sets of experiments were performed. The first set (1-D) vertically loaded a subaqueous corn syrup substrate (capturing the rheology of subsurface salt as a Newtonian fluid) with walnut sand. The second set (2-D) of experiments prograded a walnut sediment clinoform across a corn syrup substrate. We systematically varied sedimentation rate, substrate thickness, and, in the case of the prograding clinoform, base level. In no cases did we successfully reproduce a series of minibasins similar to those observed in natural settings. Instead the substrate was simply displaced laterally as sediment was deposited, forming a single depression. High sedimentation rates tended to produce wider zones of subsidence, however, if given

  4. Improved field experimental designs and quantitative evaluation of aquatic ecosystems

    SciTech Connect

    McKenzie, D.H.; Thomas, J.M.

    1984-05-01

    The paired-station concept and a log transformed analysis of variance were used as methods to evaluate zooplankton density data collected during five years at an electrical generation station on Lake Michigan. To discuss the example and the field design necessary for a valid statistical analysis, considerable background is provided on the questions of selecting (1) sampling station pairs, (2) experimentwise error rates for multi-species analyses, (3) levels of Type I and II error rates, (4) procedures for conducting the field monitoring program, and (5) a discussion of the consequences of violating statistical assumptions. Details for estimating sample sizes necessary to detect changes of a specified magnitude are included. Both statistical and biological problems with monitoring programs (as now conducted) are addressed; serial correlation of successive observations in the time series obtained was identified as one principal statistical difficulty. The procedure reduces this problem to a level where statistical methods can be used confidently. 27 references, 4 figures, 2 tables.

  5. Evaluation of flow field approximations for transonic compressor stages

    SciTech Connect

    Dorney, D.J.; Sharma, O.P.

    1997-07-01

    The flow through gas turbine compressors is often characterized by unsteady, transonic, and viscous phenomena. Accurately predicting the behavior of these complex multi-blade-row flows with unsteady rotor-stator interacting Navier-Stokes analyses can require enormous computer resources. In this investigation, several methods for predicting the flow field, losses, and performance quantities associated with axial compressor stages are presented. The methods studied include: (1) the unsteady fully coupled blade row technique, (2) the steady coupled blade row method, (3) the steady single blade row technique, and (4) the loosely coupled blade row method. The analyses have been evaluated in terms of accuracy and efficiency.

  6. Evaluation of near field rock treatment during constructions (LADSfeature #22)

    SciTech Connect

    Sonnenthal, Eric; Spycher, Nicolas

    1998-11-24

    The purpose of this report is to evaluate the effect of near-field rock treatment by injection of reactive material (calcite) above the drift for the purpose of decreasing postclosure drift seepage. The method used for the calculation was a coupled reaction-transport numerical model for gas-water-rock interaction. This includes the mass conservation of heat, liquid and gas for thermohydrological calculations, of aqueous and gaseous species for advective and diffusive transport, and the kinetics of mineral-water reactions.

  7. Evaluation of abutment scour prediction equations with field data

    USGS Publications Warehouse

    Benedict, S.T.; Deshpande, N.; Aziz, N.M.

    2007-01-01

    The U.S. Geological Survey, in cooperation with FHWA, compared predicted abutment scour depths, computed with selected predictive equations, with field observations collected at 144 bridges in South Carolina and at eight bridges from the National Bridge Scour Database. Predictive equations published in the 4th edition of Evaluating Scour at Bridges (Hydraulic Engineering Circular 18) were used in this comparison, including the original Froehlich, the modified Froehlich, the Sturm, the Maryland, and the HIRE equations. The comparisons showed that most equations tended to provide conservative estimates of scour that at times were excessive (as large as 158 ft). Equations also produced underpredictions of scour, but with less frequency. Although the equations provide an important resource for evaluating abutment scour at bridges, the results of this investigation show the importance of using engineering judgment in conjunction with these equations.

  8. Evaluating alternative exposure indices in epidemiologic studies on extremely low-frequency magnetic fields

    SciTech Connect

    Juutilainen, J.; Hatfield, T.; Laeaerae, E.

    1996-05-01

    Choosing the right exposure index for epidemiological studies on 50--60 Hz magnetic fields is difficult due to the lack of knowledge about critical exposure parameters for the biological effects of magnetic fields. This paper uses data from a previously published epidemiological investigation on early pregnancy loss (EPL) to study the methods of evaluating the exposure-response relationship of 50 Hz magnetic fields. Two approaches were used. The first approach was to apply generalized additive modeling to suggest the functional form of the relationship between EPL data with eight alternative exposure indices: the 24 h average of magnetic field strength, three indices measuring the proportion of time above specified thresholds, and four indices measuring the proportion of time within specified intensity windows. Because the original exposure data included only spot measurements, estimates for the selected exposure indices were calculated indirectly form the spot measurements using empirical nonlinear equations derived from 24 h recording in 60 residences. The results did not support intensity windows, and a threshold-type dependence on field strength appeared to be more plausible than a linear relationship. In addition, the study produced data suggesting that spot measurements may be used as surrogates for other exposure indices besides the time average field strength. No final conclusions should be drawn from this study alone, but the authors hope that this exercise stimulates evaluation of alternative exposure indices in other planned and ongoing epidemiological studies.

  9. Statistical characterization of bed roughness due to bed forms: A field study in the Elbe River at Aken, Germany

    NASA Astrophysics Data System (ADS)

    Aberle, J.; Nikora, V.; Henning, M.; Ettmer, B.; Hentschel, B.

    2010-03-01

    Bed form geometry and dynamics in a straight section of the Elbe River in Germany is analyzed considering the measured bed surfaces as two-dimensional random fields of bed elevations. Statistically derived roughness parameters are evaluated from high-resolution digital elevation models, which were available for a range of flow rates from low flows to floods. The key results relate to the identification of characteristic scaling regions in the bed surface spectra, and to observed relationships between water discharge and both the standard deviation and a factor of the "-3" spectral law of bed elevations. Two-dimensional second-order structure functions of bed elevations are also analyzed to gain further insight into the spatial structure of sand wave beds. In addition, the interrelations between flow rate hysteresis and the statistical structure of bed forms, as well as effects of channel modification by groynes, are highlighted and discussed. The reported results demonstrate that statistical parameters of bed forms may be used for characterization and prediction of flow-dependent sand bed roughness.

  10. Field observations of seismic velocity changes caused by shaking-induced damage and healing due to mesoscopic nonlinearity

    NASA Astrophysics Data System (ADS)

    Gassenmeier, M.; Sens-Schönfelder, C.; Eulenfeld, T.; Bartsch, M.; Victor, P.; Tilmann, F.; Korn, M.

    2016-03-01

    To investigate temporal seismic velocity changes due to earthquake related processes and environmental forcing in Northern Chile, we analyse 8 yr of ambient seismic noise recorded by the Integrated Plate Boundary Observatory Chile (IPOC). By autocorrelating the ambient seismic noise field measured on the vertical components, approximations of the Green's functions are retrieved and velocity changes are measured with Coda Wave Interferometry. At station PATCX, we observe seasonal changes in seismic velocity caused by thermal stress as well as transient velocity reductions in the frequency range of 4-6 Hz. Sudden velocity drops occur at the time of mostly earthquake-induced ground shaking and recover over a variable period of time. We present an empirical model that describes the seismic velocity variations based on continuous observations of the local ground acceleration. The model assumes that not only the shaking of large earthquakes causes velocity drops, but any small vibrations continuously induce minor velocity variations that are immediately compensated by healing in the steady state. We show that the shaking effect is accumulated over time and best described by the integrated envelope of the ground acceleration over the discretization interval of the velocity measurements, which is one day. In our model, the amplitude of the velocity reduction as well as the recovery time are proportional to the size of the excitation. This model with two free scaling parameters fits the data of the shaking induced velocity variation in remarkable detail. Additionally, a linear trend is observed that might be related to a recovery process from one or more earthquakes before our measurement period. A clear relationship between ground shaking and induced velocity reductions is not visible at other stations. We attribute the outstanding sensitivity of PATCX to ground shaking and thermal stress to the special geological setting of the station, where the subsurface material