Fluorine follows water: Effect on electrical conductivity of silicate minerals by experimental constraints from phlogopite

NASA Astrophysics Data System (ADS)

Li, Yan; Jiang, Haotian; Yang, Xiaozhi

2017-11-01

Fluorine and hydroxyl groups are minor constituents of silicate minerals, and share a lot of similarities concerning their physical and chemical properties. Hydroxyl groups significantly enhance the electrical conductivity of many silicate minerals, and it is expected that fluorine would have a comparable effect. This, however, has never been documented quantitatively. Here we present experimental approaches on this issue, by investigating the electrical conductivity of phlogopite with a wide range of fluorine content (but with broadly similar contents for other major elements). Electrical conductivities of gem-quality single crystal phlogopites, with samples prepared along the same orientation (normal to the (0 0 1) plane), were determined at 1 GPa and 200-650 °C using an end-loaded piston cylinder apparatus and a Solartron-1260 Impedance/Gain Phase Analyzer over the frequency range of 106 to 0.1 Hz. The complex spectra usually show an arc in the high frequency range and a short tail in the low frequency range, which are caused by lattice conduction and electrode effects, respectively. The electrical conductivity increases with increasing fluorine content, and the main charge carriers are fluorine. The activation enthalpies are ∼180 to 200 kJ/mol, nearly independent of fluorine content. The conductivity is linearly proportional to the content of fluorine, with an exponent factor of ∼1. The results demonstrate that conduction by fluorine leads to very high electrical conductivity at high temperatures. The influence of fluorine on electrical conductivity may be compared to that of hydrogen in nominally anhydrous minerals. This, along with the close association of fluorine and hydroxyl groups in silicate minerals and their similar crystal-chemical behaviors, suggests a more general role of fluorine in enhancing the electrical conductivity of many silicate minerals. Fluorine-rich assemblages, e.g., phlogopite and amphibole, could be locally enriched in the upper mantle, and if they form connected networks as observed for some natural samples, regionally high electrical conductivities could be produced. It has been recently proposed that the transition zone is probably a major reservoir for fluorine in the mantle, due to the significant dissolution of fluorine in wadsleyite and ringwoodite and the coupled incorporation with hydroxyl groups. As such, geophysically-resolved high electrical conductivities in the transition zone may be accounted for by fluorine in the dominant minerals, rather than by hydroxyl groups. The results of this work would stimulate a wide scope of future studies on the deep fluorine cycle, the deep water cycle and the geodynamical properties of the mantle.

Trap Modulated Charge Carrier Transport in Polyethylene/Graphene Nanocomposites.

PubMed

Li, Zhonglei; Du, Boxue; Han, Chenlei; Xu, Hang

2017-06-21

The role of trap characteristics in modulating charge transport properties is attracting much attentions in electrical and electronic engineering, which has an important effect on the electrical properties of dielectrics. This paper focuses on the electrical properties of Low-density Polyethylene (LDPE)/graphene nanocomposites (NCs), as well as the corresponding trap level characteristics. The dc conductivity, breakdown strength and space charge behaviors of NCs with the filler content of 0 wt%, 0.005 wt%, 0.01 wt%, 0.1 wt% and 0.5 wt% are studied, and their trap level distributions are characterized by isothermal discharge current (IDC) tests. The experimental results show that the 0.005 wt% LDPE/graphene NCs have a lower dc conductivity, a higher breakdown strength and a much smaller amount of space charge accumulation than the neat LDPE. It is indicated that the graphene addition with a filler content of 0.005 wt% introduces large quantities of deep carrier traps that reduce charge carrier mobility and result in the homocharge accumulation near the electrodes. The deep trap modulated charge carrier transport attributes to reduce the dc conductivity, suppress the injection of space charges into polymer bulks and enhance the breakdown strength, which is of great significance in improving electrical properties of polymer dielectrics.

Progress to a Gallium-Arsenide Deep-Center Laser

PubMed Central

Pan, Janet L.

2009-01-01

Although photoluminescence from gallium-arsenide (GaAs) deep-centers was first observed in the 1960s, semiconductor lasers have always utilized conduction-to-valence-band transitions. Here we review recent materials studies leading to the first GaAs deep-center laser. First, we summarize well-known properties: nature of deep-center complexes, Franck-Condon effect, photoluminescence. Second, we describe our recent work: insensitivity of photoluminescence with heating, striking differences between electroluminescence and photoluminescence, correlation between transitions to deep-states and absence of bandgap-emission. Room-temperature stimulated-emission from GaAs deep-centers was observed at low electrical injection, and could be tuned from the bandgap to half-the-bandgap (900–1,600 nm) by changing the electrical injection. The first GaAs deep-center laser was demonstrated with electrical injection, and exhibited a threshold of less than 27 mA/cm2 in continuous-wave mode at room temperature at the important 1.54 μm fiber-optic wavelength. This small injection for laser action was explained by fast depopulation of the lower state of the optical transition (fast capture of free holes onto deep-centers), which maintains the population inversion. The evidence for laser action included: superlinear L-I curve, quasi-Fermi level separations satisfying Bernard-Duraffourg’s criterion, optical gains larger than known significant losses, clamping of the optical-emission from lossy modes unable to reach laser action, pinning of the population distribution during laser action.

Electrical Properties of the Hanging Wall of the Alpine Fault, New Zealand, from DFDP-2 Wireline Data

NASA Astrophysics Data System (ADS)

Remaud, L.; Doan, M. L.; Pezard, P. A.; Celerier, B. P.; Townend, J.; Sutherland, R.; Toy, V.

2015-12-01

The DFDP-2B borehole drilled at Whataroa, New Zealand, provides a first-hand rare opportunity to investigate the damage pattern next to a major active fault. It was drilled along more than 893 m (820 m TVD) within hanging-wall protomylonites and mylonites. The interval between 264 m and 886 m (measured depth) was intensively investigated by wireline logging. Notably, electrical laterolog data were recorded over almost 3 km of cumulative logs, providing a homogeneous, uniformly sampled recording of the electrical properties of the borehole wall. The laterolog tool measures resistivity with two different electrode configurations, and hence achieves two different depths of penetration. Numerical simulations of the tool's response show that the true resistivity of the rock is close to the deep resistivity measurement, which in DFDP-2 varies between 300 Ω.m and 700 Ω.m. The shallow resistivity is about 75% of this value, as it is more sensitive to the presence of conductive borehole fluid. However, the large borehole diameter (averaging 8.5 inch = or 21.59 cm) only partially explains this value. The strong anisotropy suggested by laboratory measurements on outcrop samples also contributes to the separation between deep and shallow resistivity. The shallow and deep resistivities exhibit many significant drops that are coincident with the presence of fractures detected in borehole televiewer data. More than 700 electrical anomalies have been manually picked. The major ones are correlated with attenuation of the sonic data and sometimes with anomalies in fluid conductivity (temperature and conductivity). Their frequency gradually increases with depth, reaching a plateau below 700 m. This increase with depth may be related to closer proximity to the Alpine Fault.

Electrical conductivity of Icelandic deep geothermal reservoirs: insight from HT-HP laboratory experiments

NASA Astrophysics Data System (ADS)

Nono, Franck; Gibert, Benoit; Loggia, Didier; Parat, Fleurice; Azais, Pierre; Cichy, Sarah

2016-04-01

Although the Icelandic geothermal system has been intensively investigated over the years, targeting increasingly deeper reservoirs (i.e. under supercritical conditions) requires a good knowledge of the behaviour of physical properties of the host rock in order to better interpret large scale geophysical observations. In particular, the interpretation of deep electrical soundings remains controversial as only few studies have investigated the influence of altered minerals and pore fluid properties on electrical properties of rocks at high temperature and pressure. In this study, we investigate the electrical conductivity of drilled samples from different Icelandic geothermal fields at elevated temperature, confining pressure and pore pressure conditions (100°C < T < 600°C, confining pressure up to 100 MPa and pore pressure up to 35 MPa). The investigated rocks are composed of hyaloclastites, dolerites and basalts taken from depths of about 800 m for the hyaloclastites, to almost 2500 m for the dolerites. They display different porosity structures, from vuggy and intra-granular to micro-cracked porosities, and have been hydrothermally alterated in the chlorite to amphibolite facies. Electrical conductivity measurements are first determined at ambient conditions as a function of pore fluid conductivity in order to establish their relationships with lithology and pore space topology, prior to the high pressure and temperature measurements. Cementation factor varies from 1.5 for the dolerites to 2.83 for the basalt, reflecting changes in the shape of the conductive channels. The surface conductivities, measured at very low fluid conductivity, increases with the porosity and is correlated with the cation exchange capacity. At high pressure and temperature, we used the two guard-ring electrodes system. Measurements have been performed in dry and saturated conditions as a function of temperature and pore pressure. The supercritical conditions have been investigated and temperature cycles have been performed systematically. Dry electrical conductivity measurements show for most of the samples irreversible changes when temperatures exceed 500°C. These changes are interpreted as destabilization/dehydration of alteration minerals that could lead to the presence of a conductive fluid phase in the samples. Very low and high salinity (NaCl) electrical conductivity measurements have been performed as a function of temperature. At supercritical conditions, electrical conductivity at low salinity is not pore pressure dependent and surface conduction is preponderant. At saturated conditions, the rock's electrical conductivity increases linearly (as a function of T-1) until 350°C. Above 350°C, the conductivity decreases. All rock types exhibit the same increasing rate. This work was funded by the of the EC project IMAGE (Integrated Methods for Advanced Geothermal Exploration, grant agreement No. 608553).

In vivo mapping of current density distribution in brain tissues during deep brain stimulation (DBS)

NASA Astrophysics Data System (ADS)

Sajib, Saurav Z. K.; Oh, Tong In; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

2017-01-01

New methods for in vivo mapping of brain responses during deep brain stimulation (DBS) are indispensable to secure clinical applications. Assessment of current density distribution, induced by internally injected currents, may provide an alternative method for understanding the therapeutic effects of electrical stimulation. The current flow and pathway are affected by internal conductivity, and can be imaged using magnetic resonance-based conductivity imaging methods. Magnetic resonance electrical impedance tomography (MREIT) is an imaging method that can enable highly resolved mapping of electromagnetic tissue properties such as current density and conductivity of living tissues. In the current study, we experimentally imaged current density distribution of in vivo canine brains by applying MREIT to electrical stimulation. The current density maps of three canine brains were calculated from the measured magnetic flux density data. The absolute current density values of brain tissues, including gray matter, white matter, and cerebrospinal fluid were compared to assess the active regions during DBS. The resulting current density in different tissue types may provide useful information about current pathways and volume activation for adjusting surgical planning and understanding the therapeutic effects of DBS.

The Properties of p-GaN with Different Cp2Mg/Ga Ratios and Their Influence on Conductivity

NASA Astrophysics Data System (ADS)

Shang, Lin; Ma, Shufang; Liang, Jian; Li, Tianbao; Yu, Chunyan; Liu, Xuguang; Xu, Bingshe

2016-06-01

The effect of Cp2Mg/Ga ratio on the properties of p-GaN was explored by scanning Hall probe, photoluminescence (PL), and atomic force microscopy measurement. It was found that p-GaN has an optimal doping concentration under 2% Cp2Mg/Ga ratio, and higher or lower doping concentration is not beneficial to the conductivity. Hole concentration under the optimum condition is 4.2 × 1017 cm-3 at room temperature. If the Cp2Mg/Ga ratio exceeds the optimum value of 2%, surface morphology and electrical conduction properties become poor, and blue emission at 440 nm, considered deep donor-to-acceptor pair transitions in the PL spectra, are dominant. The decrease in electrical properties indicates the existence of compensating donors because the hole concentration decreases at such high Cp2Mg/Ga ratio. The obtained results indicate that Mg is not incorporated in the exact acceptor site under a heavy doping condition, but acts as a deep donor, instead.

Bio-heat transfer model of deep brain stimulation-induced temperature changes

NASA Astrophysics Data System (ADS)

Elwassif, Maged M.; Kong, Qingjun; Vazquez, Maribel; Bikson, Marom

2006-12-01

There is a growing interest in the use of chronic deep brain stimulation (DBS) for the treatment of medically refractory movement disorders and other neurological and psychiatric conditions. Fundamental questions remain about the physiologic effects of DBS. Previous basic research studies have focused on the direct polarization of neuronal membranes by electrical stimulation. The goal of this paper is to provide information on the thermal effects of DBS using finite element models to investigate the magnitude and spatial distribution of DBS-induced temperature changes. The parameters investigated include stimulation waveform, lead selection, brain tissue electrical and thermal conductivities, blood perfusion, metabolic heat generation during the stimulation and lead thermal conductivity/heat dissipation through the electrode. Our results show that clinical DBS protocols will increase the temperature of surrounding tissue by up to 0.8 °C depending on stimulation/tissue parameters.

Deep conductivity characteristics and preliminary acquaintance of the Lushan earthquake, east edge of Tibetan Plateau, China

NASA Astrophysics Data System (ADS)

Zhou, J.; Wang, X.; Wang, Y.; Min, G.

2013-12-01

1. Introduction The Longmenshan foreland basin developed as a flexural foredeep at western Yangtze Platfrom during the Late Triassic Indosinian orogeny with strong tectonic activity. 2008 Wenchuan earthquake (Mw7.9) happened along the middle segment of the Longmenshan overthrusting belt. 2013 Lushan earthquake (Mw6.6) occurred along the south segment of Longmenshan tectonic zone which belongs to seismic gap during the Wenchuan earthquake. The recent researches ( Yan Zhan etc., 2013; Zhuqi Zhang etc., 2013; Xiwei Xu etc., 2013) indicate that the Lushan earthquake may closely related to the activity of Longmenshan ';s piedmont fault zone while the seismogenic fault and other issues are still controversial. In order to provide an electromagnetic basis in deep earthquake area structure, we detect magnetotelluric(MT) sounding in Lushan earthquake zone to obtain the electrical structure characteristics of Longmenshan's south segment. 2. Data acquisition and processing To research the deep electrical structure of earthquake zone assigning a MT profile through the epicenter which transects the Sichuan platform concave, Longmenshan tectonic belt and Songpan-Ganzi fold system. To analysis the MT data, we carried out the impedance tensor decompositionincluding the swift rotation and bahr method which based on the phase deviation. Ultimately, NLCG method was adopted to inverse MT data. 3. Conclusion The result of MT data discloses deep electrical structure feature of the southern section of Longmenshan overthrusting belt: the burial depth of conductive layer in the upper crust of Songpan-Ganzi plot is larger than that of middle-northern part; there is no conductive zone in Longmenshan high resistance body which connect with the high conductivity layer in the crust of the western section of Songpan-Ganzi plot; there exists a relatively large range of conductive zone in the basin to Longmenshan tectonic belt, which is mostly related to the piedmont of concealed fault zone and resistive intermediate belt at the edge of western basin. Be different form Wenchuan earthquake, Lushan earthquake located in the south of Longmenshan tectonic zone which have a strong connection with the piedmont fault. MT research reveals the difference of the deep electrical structure between the south of Longmenshan tectonic belt and the middle-north belt, from which we can infer that the seismogenic environment are not the same. The epicenter of Lushan earthquake occurred in the east edge of Longmenshan tectonic belt which close to Longmenshan ';s piedmont fault combine with the MT inversion infer that Lushan earthquake has a stronger relationship with Longmenshan ';s piedmont fault. Because of the short term of our work, now further work is ongoing.

Molecular modeling of diffusion coefficient and ionic conductivity of CO2 in aqueous ionic solutions.

PubMed

Garcia-Ratés, Miquel; de Hemptinne, Jean-Charles; Bonet Avalos, Josep; Nieto-Draghi, Carlos

2012-03-08

Mass diffusion coefficients of CO(2)/brine mixtures under thermodynamic conditions of deep saline aquifers have been investigated by molecular simulation. The objective of this work is to provide estimates of the diffusion coefficient of CO(2) in salty water to compensate the lack of experimental data on this property. We analyzed the influence of temperature, CO(2) concentration,and salinity on the diffusion coefficient, the rotational diffusion, as well as the electrical conductivity. We observe an increase of the mass diffusion coefficient with the temperature, but no clear dependence is identified with the salinity or with the CO(2) mole fraction, if the system is overall dilute. In this case, we notice an important dispersion on the values of the diffusion coefficient which impairs any conclusive statement about the effect of the gas concentration on the mobility of CO(2) molecules. Rotational relaxation times for water and CO(2) increase by decreasing temperature or increasing the salt concentration. We propose a correlation for the self-diffusion coefficient of CO(2) in terms of the rotational relaxation time which can ultimately be used to estimate the mutual diffusion coefficient of CO(2) in brine. The electrical conductivity of the CO(2)-brine mixtures was also calculated under different thermodynamic conditions. Electrical conductivity tends to increase with the temperature and salt concentration. However, we do not observe any influence of this property with the CO(2) concentration at the studied regimes. Our results give a first evaluation of the variation of the CO(2)-brine mass diffusion coefficient, rotational relaxation times, and electrical conductivity under the thermodynamic conditions typically encountered in deep saline aquifers.

Electrical conductivity structure of the mantle derived from inversion of geomagnetic observatory data: implications for lateral variations in temperature, composition and water content.

NASA Astrophysics Data System (ADS)

Munch, Federico; Grayver, Alexander; Khan, Amir; Kuvshinov, Alexey

2017-04-01

As most of Earth's interior remains geochemically unsampled, geophysical techniques based on seismology, geodesy, gravimetry, and electromagnetic studies play prominent roles because of their ability to sense structure at depth. Although seismic tomography maps show a variety of structures, separating thermal and compositional contributions from seismic velocities alone still remains a challenging task. Alternatively, as electrical conductivity is sensitive to temperature, chemical composition, oxygen fugacity, water content, and the presence of melt, it can serve for determining chemistry, mineralogy, and physical structure of the deep mantle. In this work we estimate and invert local C-responses (period range 3-100 days) for a number of worldwide geomagnetic observatories to map lateral variations of electrical conductivity in Earth's mantle (400-1600 km depth). The obtained conductivity profiles are interpreted in terms of basalt fraction in a basalt-harzburgite mixture, temperature structure, and water content variations. Interpretation is based on a self-consistent thermodynamic calculation of mineral phase equilibria, electrical conductivity databases, and probabilistic inverse methods.

Giant magmatic water reservoirs at mid-crustal depth inferred from electrical conductivity and the growth of the continental crust

NASA Astrophysics Data System (ADS)

Laumonier, Mickael; Gaillard, Fabrice; Muir, Duncan; Blundy, Jon; Unsworth, Martyn

2017-01-01

The formation of the continental crust at subduction zones involves the differentiation of hydrous mantle-derived magmas through a combination of crystallization and crustal melting. However, understanding the mechanisms by which differentiation occurs at depth is hampered by the inaccessibility of the deep crust in active continental arcs. Here we report new high-pressure electrical conductivity and petrological experiments on hydrated andesitic melt from Uturuncu volcano on the Bolivian Altiplano. By applying our results to regional magnetotelluric data, we show that giant conductive anomalies at mid-crustal levels in several arcs are characterized by relatively low amounts of intergranular andesitic partial melts with unusually high dissolved water contents (≥8 wt.% H2O). Below Uturuncu, the Altiplano-Puna Magma Body (APMB) displays an electrical conductivity that requires high water content (up to 10 wt.%) dissolved in the melt based on crystal-liquid equilibria and melt H2O solubility experiments. Such a super-hydrous andesitic melt must constitute about 10% of the APMB, the remaining 90% being a combination of magmatic cumulates and older crustal rocks. The crustal ponding level of these andesites at around 6 kbar pressure implies that on ascent through the crust hydrous magmas reach their water saturation pressure in the mid-crust, resulting in decompression-induced crystallization that increases magma viscosity and in turn leads to preferential stalling and differentiation. Similar high conductivity features are observed beneath the Cascades volcanic arc and Taupo Volcanic Zone. This suggests that large amounts of water in super-hydrous andesitic magmas could be a common feature of active continental arcs and may illustrate a key step in the structure and growth of the continental crust. One Sentence Summary: Geophysical, laboratory conductivity and petrological experiments reveal that deep electrical conductivity anomalies beneath the Central Andes, Cascades and Taupo Volcanic Zone image the ponding of super-hydrous andesitic melts which contributes to the growth of continental crust.

Electrical current flow at conductive nanowires formed in GaN thin films by a dislocation template technique

NASA Astrophysics Data System (ADS)

Amma, Shin-ichi; Tokumoto, Yuki; Edagawa, Keiichi; Shibata, Naoya; Mizoguchi, Teruyasu; Yamamoto, Takahisa; Ikuhara, Yuichi

2010-05-01

Conductive nanowires were fabricated in GaN thin film by selectively doping of Al along threading dislocations. Electrical current flow localized at the nanowires was directly measured by a contact mode atomic force microscope. The current flow at the nanowires was considered to be Frenkel-Poole emission mode, suggesting the existence of the deep acceptor level along the nanowires as a possible cause of the current flow. The results obtained in this study show the possibility for fabricating nanowires using pipe-diffusion at dislocations in solid thin films.

Improving our understanding of hydraulic-electrical relations: A case study of the surficial aquifer in Emirate Abu Dhabi

USGS Publications Warehouse

Ikard, Scott; Kress, Wade

2016-01-01

Transmissivity is a bulk hydraulic property that can be correlated with bulk electrical properties of an aquifer. In aquifers that are electrically-resistive relative to adjacent layers in a horizontally stratified sequence, transmissivity has been shown to correlate with bulk transverse resistance. Conversely, in aquifers that are electrically-conductive relative to adjacent layers, transmissivity has been shown to correlate with bulk longitudinal conductance. In both cases, previous investigations have relied on small datasets (on average less than eight observations) that have yielded coefficients of determination (R2) that are typically in the range of 0.6 to 0.7 to substantiate these relations. Compared to previous investigations, this paper explores hydraulic-electrical relations using a much larger dataset. Geophysical data collected from 26 boreholes in Emirate Abu Dhabi, United Arab Emirates, are used to correlate transmissivity modeled from neutron porosity logs to the bulk electrical properties of the surficial aquifer that are computed from deep-induction logs. Transmissivity is found to be highly correlated with longitudinal conductance. An R2 value of 0.853 is obtained when electrical effects caused by variations in pore-fluid salinity are taken into consideration.

Electromagnetic studies of global geodynamic processes

NASA Astrophysics Data System (ADS)

Tarits, Pascal

1994-03-01

The deep electromagnetic sounding (DES) technique is one of the few geophysical methods, along with seismology, gravity, heat flow, which may be use to probe the structure of the Earth's mantle directly. The interpretation of the DESs may provide electrical conductivity profiles down to the upper part of the lower mantle. The electrical conductivity is extremely sensitive to most of the thermodynamic processes we believe are acting in the Earth's mantle (temperature increases, partial melting, phase transition and to a lesser extent pressure). Therefore, in principle, results from DES along with laboratory measurements could be used to constrain models of these processes. The DES technique is reviewed in the light of recent results obtained in a variety of domains: data acquisition and analysis, global induction modeling and data inversion and interpretation. The mechanisms and the importance of surface distortions of the DES data are reviewed and techniques to model them are discussed. The recent results in terms of the conductivity distribution in the mantle from local and global DES are presented and a tentative synthesis is proposed. The geodynamic interpretations of the deep conductivity structures are reviewed. The existence of mantle lateral heterogeneities in conductivity at all scales and depths for which electromagnetic data are available is now well documented. A comparison with global results from seismology is presented.

Deep electrical resistivity structure of northwestern Costa Rica

NASA Astrophysics Data System (ADS)

Brasse, H.; Kapinos, G.; Mütschard, L.; Alvarado, G. E.; Worzewski, T.; Jegen, M.

2009-01-01

First long-period magnetotelluric investigations were conducted in early 2008 in northwestern Costa Rica, along a profile that extends from the coast of the Pacific Ocean, traverses the volcanic arc and ends currently at the Nicaraguan border. The aim of this study is to gain insight into the electrical resistivity structure and thus fluid distribution at the continental margin where the Cocos plate subducts beneath the Caribbean plate. Preliminary two-dimensional models map the only moderately resistive mafic/ultramafic complexes of the Nicoya Peninsula (resistivity of a few hundred Ωm), the conductive forearc and the backarc basins (several Ωm). Beneath the backarc basin the data image a poor conductor in the basement with a clear termination in the south, which may tentatively be interpreted as the Santa Elena Suture. The volcanic arc shows no pronounced anomaly at depth, but a moderate conductor underlies the backarc with a possible connection to the upper mantle. A conductor at deep-crustal levels in the forearc may reflect fluid release from the downgoing slab.

Determination of water saturation using gas phase partitioning tracers and time-lapse electrical conductivity measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Timothy C.; Oostrom, Martinus; Truex, Michael J.

2013-05-21

Water saturation is an important indicator of contaminant distribution and plays a governing role in contaminant transport within the vadose zone. Understanding the water saturation distribution is critical for both remediation and contaminant flux monitoring in unsaturated environments. In this work we propose and demonstrate a method of remotely determining water saturation levels using gas phase partitioning tracers and time-lapse bulk electrical conductivity measurements. The theoretical development includes the partitioning chemistry for the tracers we demonstrate (ammonia and carbon dioxide), as well as a review of the petrophysical relationship governing how these tracers influence bulk conductivity. We also investigate methodsmore » of utilizing secondary information provided by electrical conductivity breakthrough magnitudes induced by the tracers. We test the method on clean, well characterized, intermediate-scale sand columns under controlled conditions. Results demonstrate the capability to predict partitioning coefficients and accurately monitor gas breakthrough curves along the length of the column according to the corresponding electrical conductivity response, leading to accurate water saturation estimates. This work is motivated by the need to develop effective characterization and monitoring techniques for contaminated deep vadose zone environments, and provides a proof-of-concept toward uniquely characterizing and monitoring water saturation levels at the field scale and in three-dimensions using electrical resistivity tomography.« less

A new look at deep-sea video

USGS Publications Warehouse

Chezar, H.; Lee, J.

1985-01-01

A deep-towed photographic system with completely self-contained recording instrumentation and power can obtain color-video and still-photographic transects along rough terrane without need for a long electrically conducting cable. Both the video- and still-camera systems utilize relatively inexpensive and proven off-the-shelf hardware adapted for deep-water environments. The small instrument frame makes the towed sled an ideal photographic tool for use on ship or small-boat operations. The system includes a temperature probe and altimeter that relay data acoustically from the sled to the surface ship. This relay enables the operator to monitor simultaneously water temperature and the precise height off the bottom. ?? 1985.

Profiling soil water content sensor

USDA-ARS?s Scientific Manuscript database

A waveguide-on-access-tube (WOAT) sensor system based on time domain reflectometry (TDR) principles was developed to sense soil water content and bulk electrical conductivity in 20-cm (8 inch) deep layers from the soil surface to depths of 3 m (10 ft) (patent No. 13/404,491 pending). A Cooperative R...

Biogeochemical processes controlling density stratification in an iron-meromictic lake

NASA Astrophysics Data System (ADS)

Nixdorf, E.; Boehrer, B.

2015-06-01

Biogeochemical processes and mixing regime of a lake can control each other mutually. The prominent case of iron meromixis is investigated in Waldsee near Doebern, a small lake that originated from surface mining of lignite. From a four years data set of monthly measured electrical conductivity profiles, we calculated summed conductivity as a quantitative variable reflecting the amount of electro-active substances in the entire lake. Seasonal variations followed changing chemocline height. Coinciding changes of electrical conductivities in the monimolimnion indicated that a considerable share of substances, precipitated by the advancing oxygenated epilimnion, re-dissolved in the remaining anoxic deep waters and contributed considerably to the density stratification. In addition, we constructed a lab experiment, in which aeration of monimolimnetic waters removed iron compounds and organic material. Precipitates could be identified by visual inspection. Introduced air bubbles ascended through the water column and formed a water mass similar to the mixolimnetic Waldsee water. The remaining less dense water remained floating on the nearly unchanged monimolimnetic water. In conclusion, iron meromixis as seen in Waldsee did not require two different sources of incoming waters, but the inflow of iron rich deep groundwater and the aeration through the lake surface were fully sufficient.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Constable, S.A.; Orange, Arnold S.; Hoversten, G. Michael

Induction in electrically conductive seawater attenuates themagnetotelluric (MT) fields and, coupled with a minimum around 1 Hz inthe natural magnetic field spectrum, leads to a dramatic loss of electricand magnetic field power on the sea floor at periods shorter than 1000 s,For this reason the marine MT method traditionally has been used only atperiods of 10(3) to 10(5) s to probe deep mantle structure; rarely does asea-floor MT response extend to a 100-s period. To be useful for mappingcontinental shelf structure at depths relevant to petroleum exploration,however, MT measurements need to be made at periods between 1 and 1000 s.Thismore » can be accomplished using ac-coupled sensors, induction coils forthe magnetic field, and an electric field amplifier developed for marinecontrolled-source applications. The electrically quiet sea floor allowsthe attenuated electric field to be amplified greatly before recording;in deep (l-km) water, motional noise in magnetic field sensors appearsnot to be a problem. In shallower water, motional noise does degrade themagnetic measurement, but sea-floor magnetic records can be replaced byland recordings, producing an effective sea-surface MT response. Fieldtrials of such equipment in l-km-deep water produced good-quality MTresponses at periods of 3 to 1000 s: in shallower water, responses to afew hertz can be obtained. Using an autonomous sea-floor data loggerdeveloped at Scripps Institution of Oceanography, marine surveys of 50 to100 sites are feasible.« less

The Effect of Borehole Flow on Salinity Profiles From Deep Monitor Wells in Hawaii

NASA Astrophysics Data System (ADS)

Rotzoll, K.; Hunt, C. D.; El-Kadi, A. I.

2008-12-01

Ground-water resource management in Hawaii is based partly on salinity profiles from deep wells that are used to monitor the thickness of freshwater lenses and the transition zone between freshwater and saltwater. Vertical borehole flow in these wells may confound understanding of the actual salinity-depth profiles in the basaltic aquifers and lead to misinterpretations that hamper effective water-resource management. Causes and effects of borehole flow on salinity profiles are being evaluated at 40 deep monitor wells in Hawaii. Step- like changes in fluid electrical conductivity with respect to depth are indicative of borehole flow and are evident in almost all available salinity profiles. A regional trend in borehole flow direction, expected from basin-wide ground-water flow dynamics, is evident as major downward flow components in inland recharge areas and major upward flow components in discharge areas near the coast. The midpoint of the transition zone in one deep monitor well showed inconsequential depth displacements in response to barometric pressure and tidal fluctuations and to pumping from nearby wellfields. Commonly, the 1 mS/cm conductivity value is used to indicate the top of the transition zone. Contrary to the more stable midpoint, the depth of the 1 mS/cm conductivity value may be displaced by as much as 200 m in deep monitor wells near pumping wellfields. The displacement is complemented with an increase in conductivity at a particular depth in the upper part of the profile. The observed increase in conductivity is linear with increase in nearby pumpage. The largest deviations from expected aquifer-salinity profiles occur in deep monitor wells located in the area extending from east Pearl Harbor to Kalihi on Oahu, which coincides with the most heavily pumped part of the aquifer.

Electrical Current Leakage and Open-Core Threading Dislocations in AlGaN-Based Deep Ultraviolet Light-Emitting Diodes.

DOE PAGES

Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; ...

2014-08-04

Electrical current transport through leakage paths in AlGaN-based deep ultraviolet (DUV) lightemitting diodes (LEDs) and their effect on LED performance are investigated. Open-core threading dislocations, or nanopipes, are found to conduct current through nominally insulating Al0.7Ga0.3N layers and limit the performance of DUV-LEDs. A defect-sensitive phosphoric acid etch reveals these opencore threading dislocations in the form of large, micron-scale hexagonal etch pits visible with optical microscopy, while closed-core screw-, edge-, and mixed-type threading dislocations are represented by smaller and more numerous nanometer-scale pits visible by atomic-force microscopy. The electrical and optical performances of DUV-LEDs fabricated on similar Si-doped Al0.7Ga0.3N templatesmore » are found to have a strong correlation to the density of these nanopipes, despite their small fraction (<0.1% in this study) of the total density of threading dislocations.« less

Morphology and crystalline-phase-dependent electrical insulating properties in tailored polypropylene for HVDC cables

NASA Astrophysics Data System (ADS)

Zha, Jun-Wei; Yan, Hong-Da; Li, Wei-Kang; Dang, Zhi-Min

2016-11-01

Polypropylene (PP) has become one promising material to potentially replace the cross-link polyethylene used for high voltage direct current cables. Besides the isotactic polypropylene, the block polypropylene (b-PP) and random polypropylene (r-PP) can be synthesized through the copolymerization of ethylene and propylene molecules. In this letter, the effect of morphology and crystalline phases on the insulating electrical properties of PP was investigated. It was found that the introduction of polyethylene monomer resulted in the formation of β and γ phases in b-PP and r-PP. The results from the characteristic trap energy levels indicated that the β and γ phases could induce deep electron traps which enable to capture the carriers. And the space charge accumulation was obviously suppressed. Besides, the decreased electrical conductivity was observed in b-PP and r-PP. It is attributed to the existence of deep traps which can effectively reduce the carrier mobility and density in materials.

MIS capacitor studies on silicon carbide single crystals

NASA Technical Reports Server (NTRS)

Kopanski, J. J.

1990-01-01

Cubic SIC metal-insulator-semiconductor (MIS) capacitors with thermally grown or chemical-vapor-deposited (CVD) insulators were characterized by capacitance-voltage (C-V), conductance-voltage (G-V), and current-voltage (I-V) measurements. The purpose of these measurements was to determine the four charge densities commonly present in an MIS capacitor (oxide fixed charge, N(f); interface trap level density, D(it); oxide trapped charge, N(ot); and mobile ionic charge, N(m)) and to determine the stability of the device properties with electric-field stress and temperature. The section headings in the report include the following: Capacitance-voltage and conductance-voltage measurements; Current-voltage measurements; Deep-level transient spectroscopy; and Conclusions (Electrical characteristics of SiC MIS capacitors).

Carrier Transport and Effective Barrier Height of Low Resistance Metal Contact to Highly Mg-Doped p-GaN

NASA Astrophysics Data System (ADS)

Park, Youngjun; Kim, Hyunsoo

2011-08-01

The effective barrier height and carrier transport mechanism of low resistance Ag-based contact to highly Mg-doped p-GaN were investigated. The specific contact resistance obtained was as low as 7.0×10-4 Ω cm2. The electrical resistivity of p-GaN was found to increase depending on ˜T-1/4, indicating variable-range hopping (VRH) conduction through Mg-related deep-level defects. Based on the VRH conduction model, the effective barrier height for carrier transport could be measured as 0.12 eV, which is low enough to explain the formation of excellent ohmic contact. The deep-level defects were also found to induce surface Fermi pinning.

A new petrological and geophysical investigation of the present-day plumbing system of Mount Vesuvius

NASA Astrophysics Data System (ADS)

Pommier, A.; Tarits, P.; Hautot, S.; Pichavant, M.; Scaillet, B.; Gaillard, F.

2010-07-01

A model of the electrical resistivity of Mt. Vesuvius has been elaborated to investigate the present structure of the volcanic edifice. The model is based on electrical conductivity measurements in the laboratory, on geophysical information, in particular, magnetotelluric (MT) data, and on petrological and geochemical constraints. Both 1-D and 3-D simulations explored the effect of depth, volume and resistivity of either one or two reservoirs in the structure. For each configuration tested, modeled MT transfer functions were compared to field transfer functions from field magnetotelluric studies. The field electrical data are reproduced with a shallow and very conductive layer (˜0.5 km depth, 1.2 km thick, 5 ohm.m resistive) that most likely corresponds to a saline brine present beneath the volcano. Our results are also compatible with the presence of cooling magma batches at shallow depths (<3-4 km depth). The presence of a deeper body at ˜8 km depth, as suggested by seismic studies, is consistent with the observed field transfer functions if such a body has an electrical resistivity > ˜100 ohm.m. According to a petro-physical conductivity model, such a resistivity value is in agreement either with a low-temperature, crystal-rich magma chamber or with a small quantity of hotter magma interconnected in the resistive surrounding carbonates. However, the low quality of MT field data at long periods prevent from placing strong constraints on a potential deep magma reservoir. A comparison with seismic velocity values tends to support the second hypothesis. Our findings would be consistent with a deep structure (8-10 km depth) made of a tephriphonolitic magma at 1000°C, containing 3.5 wt%H2O, 30 vol.% crystals, and interconnected in carbonates in proportions ˜45% melt -55% carbonates.

Time-multiplexed two-channel capacitive radiofrequency hyperthermia with nanoparticle mediation.

PubMed

Kim, Ki Soo; Hernandez, Daniel; Lee, Soo Yeol

2015-10-24

Capacitive radiofrequency (RF) hyperthermia suffers from excessive temperature rise near the electrodes and poorly localized heat transfer to the deep-seated tumor region even though it is known to have potential to cure ill-conditioned tumors. To better localize heat transfer to the deep-seated target region in which electrical conductivity is elevated by nanoparticle mediation, two-channel capacitive RF heating has been tried on a phantom. We made a tissue-mimicking phantom consisting of two compartments, a tumor-tissue-mimicking insert against uniform background agarose. The tumor-tissue-mimicking insert was made to have higher electrical conductivity than the normal-tissue-mimicking background by applying magnetic nanoparticle suspension to the insert. Two electrode pairs were attached on the phantom surface by equal-angle separation to apply RF electric field to the phantom. To better localize heat transfer to the tumor-tissue-mimicking insert, RF power with a frequency of 26 MHz was delivered to the two channels in a time-multiplexed way. To monitor the temperature rise inside the phantom, MR thermometry was performed at a 3T MRI intermittently during the RF heating. Finite-difference-time-domain (FDTD) electromagnetic and thermal simulations on the phantom model were also performed to verify the experimental results. As compared to the one-channel RF heating, the two-channel RF heating with time-multiplexed driving improved the spatial localization of heat transfer to the tumor-tissue-mimicking region in both the simulation and experiment. The two-channel RF heating also reduced the temperature rise near the electrodes significantly. Time-multiplexed two-channel capacitive RF heating has the capability to better localize heat transfer to the nanoparticle-mediated tumor region which has higher electrical conductivity than the background normal tissues.

Study on the Geomagnetic Short Period Variations of the Northwestern Yunnan

NASA Astrophysics Data System (ADS)

Yuan, Y.; Li, Q.; Cai, J.

2015-12-01

The Northwestern Yunnan is located in the interaction area between the Eurasian plate and the India plate. This area has been the ideal place for the research of continental dynamics and the prediction for risk region of strong earthquake for its complex tectonic environment and frequent seismic activity. Therefore the study on the geomagnetic short period variations is of great significance in the exploration of deep electrical structure, analysis of the seismic origin and deep geodynamics in the Northwestern Yunnan of China . This paper is based on the geomagnetic data from the magnetometer array with 8 sites built in the northwestern Yunnan to explore the deep electrical structure by the method of geomagnetic depth sounding. Firstly, we selected a total of 183 geomagnetic short period events at the range of 6min to 120min period. And we found a north northwest dividing line, of which two sides has the opposite value in the vertical component variation amplitude, which indicates the obvious conductivity anomaly underground. Secondly, the contour maps of the ratio of vertical component and horizontal component variation amplitude ΔZ/ΔH in different periods reflects the changes of a high conductivity belt's direction and position. In addition, the induction arrows maps within the period of 2 - 256min also shows that on the two sides of the dividing line the induction vectors deviate from each other, and the amplitude and direction of vectors varies with periods regularly. In the light of this, we infer that a high conductivity belt probably exists, which stretches from the deep crust to uppermost mantle and changes with depth constantly with the reference of magnetotelluric sounding. In the end of this paper, the staggered grid finite difference method is used to model the simplified three-dimensional high conductivity anomaly, and the result shows magnetic field distributions are consistent with the observed geomagnetic short period variations characteristics in different periods, which confirms the existence of the high conductivity belt. According to the characteristics of the short period geomagnetic variation above, in combination with the results of previous studies, the synthetic action of partial melting and fluid might be the origin of the belt.

Quaternary tectonics from seismic interpretation and its potential relation with deep geothermal fluids in the Marche (Central Italy).

NASA Astrophysics Data System (ADS)

Chicco, Jessica; Invernizzi, Chiara; Pierantoni, Pietro Paolo; Costa, Mario

2017-04-01

Knowledge of the structural features is fundamental in evaluating geothermal exchange potential and in modelling geothermal systems. In particular, faults and fractures play an important role for the circulation of fluids in the crust, and structural setting can influence groundwater flow, its regime, chemistry and electrical conductivity. In this context, data coming from accurate studies of groundwater physical properties in the Marche region (Central Italy), concerning electrical conductivity above all, revealed some anomalies in several localities that could be ascribed to a strong structural control. Data acquisition and interpretation of some SW-NE seismic reflection profiles crossing the Apennine chain to the Adriatic sea and kindly provided by ENI S.p.A, highlight important deep Plio-Quaternary structures connected with minor surface ones and to hydrogeological conditions. Seismic profiles interpretation allowed to reconstruct the structural setting and to identify the recent evolution of the Apennine Marche sector in more detail with respect to what is already known. In fact, some high angle structures affecting the whole sedimentary sequence and routing at high depth were labelled. These are NW-SE sub-parallel transpressive structures bounded by SW and NE-dipping high-angle reverse faults reaching > 10 km depth (positive flower structures), and probably involving the upper crust basement. Three main alignments were identified from W to the coast line. In some cases, flower nucleation gives rise to the lifting and counter-clockwise rotation of the Pre-Pliocene substratum blocks, with the upwelling and outcropping of Upper Miocene (Messinian) evaporite deposits along the axial zone of the transpressive structural highs. Noting the analyses of groundwater properties coming from wells placed in proximity of these structures or located along the analysed seismic profiles, anomalies in electrical conductivity are relevant. The activity of the deep rooting structures observed in the seismic profiles and the high degree of fracturing that accompanies these complex and recent fault systems can facilitate the exchange between deep and superficial fluids. In other cases, like in coastal structural high, it can have a role in preventing the sea water ingression. This significant consideration can be supported also by the direct relation of electrical conductivity with the amount of rainfall revealed from studied piezometers along the carbonate Marche ridge. It should be explained through a specific behaviour (typical of carbonate aquifers, known as the "piston-flow phase") which implies an increase of groundwater mineralization as a result of transmission of the hydraulic pressure from the saturated zone, through fractures as important way for fluids circulation. Ultimately, we suggest that the structural control could be an important factor in influencing both the surface and the groundwater flow behaviours, and then convective component of the heat transport in the studied area.

Electrical conductivity imaging in the western Pacific subduction zone

NASA Astrophysics Data System (ADS)

Utada, Hisashi; Baba, Kiyoshi; Shimizu, Hisayoshi

2010-05-01

Oceanic plate subduction is an important process for the dynamics and evolution of the Earth's interior, as it is regarded as a typical downward flow of the mantle convection that transports materials from the near surface to the deep mantle. Recent seismological study showed evidence suggesting the transportation of a certain amount of water by subduction of old oceanic plate such as the Pacific plate down to 150-200 km depth into the back arc mantle. However it is not well clarified how deep into the mantle the water can be transported. The electromagnetic induction method to image electrical conductivity distribution is a possible tool to answer this question as it is known to be sensitive to the presence of water. Here we show recent result of observational study from the western Pacific subduction zone to examine the electrical conductivity distribution in the upper mantle and in the mantle transition zone (MTZ), which will provide implications how water distributes in the mantle. We take two kinds of approach for imaging the mantle conductivity, (a) semi-global and (b) regional induction approaches. Result may be summarized as follows: (a) Long (5-30 years) time series records from 8 submarine cables and 13 geomagnetic observatories in the north Pacific region were analyzed and long period magnetotelluric (MT) and geomagnetic deep sounding (GDS) responses were estimated in the period range from 1.7 to 35 days. These frequency dependent response functions were inverted to 3-dimensional conductivity distribution in the depth range between 350 and 850 km. Three major features are suggested in the MTZ depth such as, (1) a high conductivity anomaly beneath the Philippine Sea, (2) a high conductivity anomaly beneath the Hawaiian Islands, and (3) a low conductivity anomaly beneath and in the vicinity of northern Japan. (b) A three-year long deployment of ocean bottom electro-magnetometers (OBEM's) was conducted in the Philippine Sea and west Pacific Ocean from 2005 to 2008. As a preliminary investigation, MT response functions from 20 sites in the Philippine Sea and 4 sites in the west Pacific basin in the period range between 300 and 80000 sec were respectively inverted to one-dimensional (1-D) profile of electrical conductivity by quantitatively considering the effect of the heterogeneous conductivity distribution (ocean and lands) at the surface. The resultant 1-D models show three main features: (1) Strong contrast in the conductivity for the shallower 200 km of the upper mantle depths is recognized between the two regions, which is qualitatively consistent with the difference in lithospheric age. (2) The conductivity at 200-300 km depth is more or less similar to each other at about 0.3 S /m. (3) The conductivity around the MTZ depth is higher for the Philippine Sea mantle than for the Pacific mantle, which is consistent with the implication obtained from a semi-global approach (a). As already suggested in our previous work, the high conductivity in the MTZ below the Philippine Sea can be explained by the excess conduction due to the presence of hydrogen (water) in wadesleyite or in ringwoodite. Therefore, it implies a large scale circulation of water in the back arc mantle not only in the upper mantle but also down to the MTZ depth. However, our interpretation indicates that the high conductivity of the Philippine Sea uppermost upper mantle cannot be explained only by the effect of hydrogen conduction in olivine, but that additional conduction enhancement such as the presence of partial melt is required.

Controlling charge transport mechanisms in molecular junctions: Distilling thermally induced hopping from coherent-resonant conduction.

PubMed

Kim, Hyehwang; Segal, Dvira

2017-04-28

The electrical conductance of molecular junctions may depend strongly on the temperature and weakly on molecular length, under two distinct mechanisms: phase-coherent resonant conduction, with charges proceeding via delocalized molecular orbitals, and incoherent thermally assisted multi-step hopping. While in the case of coherent conduction, the temperature dependence arises from the broadening of the Fermi distribution in the metal electrodes, in the latter case it corresponds to electron-vibration interaction effects on the junction. With the objective to distill the thermally activated hopping component, thus exposing intrinsic electron-vibration interaction phenomena on the junction, we suggest the design of molecular junctions with "spacers," extended anchoring groups that act to filter out phase-coherent resonant electrons. Specifically, we study the electrical conductance of fixed-gap and variable-gap junctions that include a tunneling block, with spacers at the boundaries. Using numerical simulations and analytical considerations, we demonstrate that in our design, resonant conduction is suppressed. As a result, the electrical conductance is dominated by two (rather than three) mechanisms: superexchange (deep tunneling) and multi-step thermally induced hopping. We further exemplify our analysis on DNA junctions with an A:T block serving as a tunneling barrier. Here, we show that the electrical conductance is insensitive to the number of G:C base-pairs at the boundaries. This indicates that the tunneling-to-hopping crossover revealed in such sequences truly corresponds to the properties of the A:T barrier.

Phased Retrofits in Existing Homes in Florida Phase I: Shallow and Deep Retrofits

DOE Office of Scientific and Technical Information (OSTI.GOV)

D. Parker; Sutherland, K.; Chasar, D.

2016-02-01

The U.S. Department of Energy (DOE) Building America program, in collaboration with Florida Power and Light (FPL), conducted a phased residential energy-efficiency retrofit program. This research sought to establish impacts on annual energy and peak energy reductions from the technologies applied at two levels of retrofit - shallow and deep, with savings levels approaching the Building America program goals of reducing whole-house energy use by 40%. Under the Phased Deep Retrofit (PDR) project, we have installed phased, energy-efficiency retrofits in a sample of 56 existing, all-electric homes. End-use savings and economic evaluation results from the phased measure packages and singlemore » measures are summarized in this report.« less

Chloride concentration gradients in tank-stored hydraulic fracturing fluids following flowback

Treesearch

Pamela J. Edwards; Linda L. Tracy; William K. Wilson

2011-01-01

A natural gas well in West Virginia was hydraulically fractured and the flowback was recovered and stored in an 18-foot-deep tank. Both in situ field test kit and laboratory measurements of electrical conductivity and chloride concentrations increased substantially with depth, although the laboratory measurements showed a greater increase. The field test kit also...

Wide Bandgap Extrinsic Photoconductive Switches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sullivan, James S.

2013-07-03

Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6HSiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductivemore » switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators.« less

Electromagnetic sounding of the moon using Apollo 16 and Lunokhod 2 surface magnetometer observations /preliminary results/

NASA Technical Reports Server (NTRS)

Vanian, L. L.; Vnutchokova, T. A.; Fainberg, E. B.; Eroschenko, E. A.; Dyal, P.; Parkin, C. W.; Daily, W. D.

1977-01-01

A technique of deep electromagnetic sounding of the moon using simultaneous magnetic-field measurements at two lunar surface sites is described. The method, used with the assumption that deep electrical conductivity is a function only of lunar radius, has the advantage of allowing calculation of the external driving field from two surface-site measurements only and therefore does not require data from a lunar orbiting satellite. A transient-response calculation is presented for the example of a magnetic-field discontinuity, measured simultaneously by Apollo 16 and Lunokhod 2 surface magnetometers.

Electromagnetic Sounding of the Moon Using Apollo 16 and Lunokhod 2 Surface Magnetometer Observations (Preliminary Results)

NASA Technical Reports Server (NTRS)

Vanyan, L. L.; Vnutchokova, T. A.; Fainberg, E. B.; Eroschenko, E. A.; Dyal, P.; Parkin, C. W.; Parkin, C. W.

1977-01-01

A new technique of deep electromagnetic sounding of the Moon using simultaneous magnetic field measurements at two lunar surface sites is described. The method, used with the assumption that deep electrical conductivity is a function only of lunar radius, has the advantage of allowing calculation of the external driving field from two surface site measurements only, and therefore does not require data from a lunar orbiting satellite. A transient response calculation is presented for the example of a magnetic field discontinuity of February 13, 1973, measured simultaneously by Apollo 16 and Lunokhod 2 surface magnetometers.

Experimental study of an adaptive elastic metamaterial controlled by electric circuits

NASA Astrophysics Data System (ADS)

Zhu, R.; Chen, Y. Y.; Barnhart, M. V.; Hu, G. K.; Sun, C. T.; Huang, G. L.

2016-01-01

The ability to control elastic wave propagation at a deep subwavelength scale makes locally resonant elastic metamaterials very relevant. A number of abilities have been demonstrated such as frequency filtering, wave guiding, and negative refraction. Unfortunately, few metamaterials develop into practical devices due to their lack of tunability for specific frequencies. With the help of multi-physics numerical modeling, experimental validation of an adaptive elastic metamaterial integrated with shunted piezoelectric patches has been performed in a deep subwavelength scale. The tunable bandgap capacity, as high as 45%, is physically realized by using both hardening and softening shunted circuits. It is also demonstrated that the effective mass density of the metamaterial can be fully tailored by adjusting parameters of the shunted electric circuits. Finally, to illustrate a practical application, transient wave propagation tests of the adaptive metamaterial subjected to impact loads are conducted to validate their tunable wave mitigation abilities in real-time.

Transient luminescence induced by electrical refilling of charge carrier traps of dislocation network at hydrophilically bonded Si wafers interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bondarenko, Anton; Vyvenko, Oleg

2014-02-21

Dislocation network (DN) at hydrophilically bonded Si wafers interface is placed in space charge region (SCR) of a Schottky diode at a depth of about 150 nm from Schottky electrode for simultaneous investigation of its electrical and luminescent properties. Our recently proposed pulsed traps refilling enhanced luminescence (Pulsed-TREL) technique based on the effect of transient luminescence induced by refilling of charge carrier traps with electrical pulses is further developed and used as a tool to establish DN energy levels responsible for D1 band of dislocation-related luminescence in Si (DRL). In present work we do theoretical analysis and simulation of trapsmore » refilling kinetics dependence on refilling pulse magnitude (Vp) in two levels model: shallow and deep. The influence of initial charge state of deep level on shallow level occupation-Vp dependence is discussed. Characteristic features predicted by simulations are used for Pulsed-TREL experimental results interpretation. We conclude that only shallow (∼0.1 eV from conduction and valence band) energetic levels in the band gap participate in D1 DRL.« less

Modeling Geoelectric Fields and Geomagnetically Induced Currents Around New Zealand to Explore GIC in the South Island's Electrical Transmission Network

NASA Astrophysics Data System (ADS)

Divett, T.; Ingham, M.; Beggan, C. D.; Richardson, G. S.; Rodger, C. J.; Thomson, A. W. P.; Dalzell, M.

2017-10-01

Transformers in New Zealand's South Island electrical transmission network have been impacted by geomagnetically induced currents (GIC) during geomagnetic storms. We explore the impact of GIC on this network by developing a thin-sheet conductance (TSC) model for the region, a geoelectric field model, and a GIC network model. (The TSC is composed of a thin-sheet conductance map with underlying layered resistivity structure.) Using modeling approaches that have been successfully used in the United Kingdom and Ireland, we applied a thin-sheet model to calculate the electric field as a function of magnetic field and ground conductance. We developed a TSC model based on magnetotelluric surveys, geology, and bathymetry, modified to account for offshore sediments. Using this representation, the thin sheet model gave good agreement with measured impedance vectors. Driven by a spatially uniform magnetic field variation, the thin-sheet model results in electric fields dominated by the ocean-land boundary with effects due to the deep ocean and steep terrain. There is a strong tendency for the electric field to align northwest-southeast, irrespective of the direction of the magnetic field. Applying this electric field to a GIC network model, we show that modeled GIC are dominated by northwest-southeast transmission lines rather than east-west lines usually assumed to dominate.

Quantitative analysis of biogeochemically controlled density stratification in an iron-meromictic lake

NASA Astrophysics Data System (ADS)

Nixdorf, E.; Boehrer, B.

2015-11-01

Lake stratification controls the cycling of dissolved matter within the water body. This is of particular interest in the case of meromictic lakes, where permanent density stratification of the deep water limits vertical transport, and a chemically different (reducing) milieu can be established. As a consequence, the geochemical setting and the mixing regime of a lake can stabilize each other mutually. We attempt a quantitative approach to the contribution of chemical reactions sustaining the density stratification. As an example, we chose the prominent case of iron meromixis in Waldsee near Doebern, a small lake that originated from near-surface underground mining of lignite. From a data set covering 4 years of monthly measured electrical conductivity profiles, we calculated summed conductivity as a quantitative variable reflecting the amount of electro-active substances in the entire lake. Seasonal variations followed the changing of the chemocline height. Coinciding changes of electrical conductivities in the monimolimnion indicated that a considerable share of substances, precipitated by the advancing oxygenated epilimnion, re-dissolved in the remaining anoxic deep waters and contributed considerably to the density stratification. In addition, we designed a lab experiment, in which we removed iron compounds and organic material from monimolimnetic waters by introducing air bubbles. Precipitates could be identified by visual inspection. Eventually, the remaining solutes in the aerated water layer looked similar to mixolimnetic Waldsee water. Due to its reduced concentration of solutes, this water became less dense and remained floating on nearly unchanged monimolimnetic water. In conclusion, iron meromixis as seen in Waldsee did not require two different sources of incoming waters, but the inflow of iron-rich deep groundwater and the aeration through the lake surface were fully sufficient for the formation of iron meromixis.

Electrical Conductivity of ɛ-Iron under Shock Compression up to 208G Pa

NASA Astrophysics Data System (ADS)

Bi, Yan; Tan, Hua; Jing, Fu-Qian

2002-02-01

The electrical conductivity of shock-compressed iron was measured up to 208 GPa by using an improved design in experiment assembly in which the iron sample was encapsulated in a single-crystal sapphire cell. High-pressure shock compressions were generated by the plate impact technique with the two-stage light-gas gun. The measured conductivity of iron varies from 1.45×104 Ω-1 cm-1 at 101 GPa and 2010 K to 7.65×103 Ω-1 cm-1 at 208 GPa and 5220 K. After examining these data together with those reported, we found that the Bloch-Grüneisen expression is still valid at high pressures and temperatures, even up to 208 GPa and 5220 K, at least for ɛ-iron, which is significant in the field of condensed matter physics and deep interior earth science.

Electrical conductivity of H2O-NaCl fluids to 10 kbar

NASA Astrophysics Data System (ADS)

Sinmyo, R.; Keppler, H.

2016-12-01

Magnetotelluric studies often reveal zones of elevated electrical conductivity in the mantle wedge above subducting slabs, in the deep crust below fold belts, or below active volcanoes. Since both aqueous fluids and hydrous silivate melts may be highly conductive, they may both account for these observations. Distinguishing between these two posssibilities, however, is difficult. One reason for this problem is that while there are very good conductivity data for silicate melts, such data do not exist for aqueous fluids under the relevant conditions of pressure, temperature and solute concentration. Most crustal and mantle fluids likely contain some NaCl, which greatly enhances conductivity due to its partial dissociation into Na+ and Cl-. We therefore studied the electrical conductivity of 0.01, 0.1 and 1 m NaCl solutions in water to 10 kbar and 600 °C. The measurements were carried out in externally-heated diamond cells containing two gaskets separated by an insulating ring of diamond, following a method described by Ni et al. (2014). The two gaskets were used as electrodes and full impedance spectra were measured from 30 Hz to 10 MHz using a Solartron 1260 impedance analyzer. Electrical conductivity was generally found to increase with pressure temperature, and fluid density. The conductivity increase observed upon variation of NaCl concentration from 0.1m to 1m was smaller than from 0.01m to 0.1m, which reflects the reduced degree of dissociation at high NaCl concentration. In general, the data show that already a very small fraction of NaCl-bearing aqueous fluid is sufficient to enhance bulk conductivities to values that would be expected for a high degree of partial melting. Accordingly, aqueous fluids may be distinguished from hydrous melts by comparing magnetotelluric and seismic data. H2O-NaCl fluids may enhance electrical conductivities with little disturbance of vp or vp/vs ratios.

Theory of copper impurities in ZnO

NASA Astrophysics Data System (ADS)

Lyons, John; Alkauskas, Audrius; Janotti, Anderson; van de Walle, Chris G.

Due to its connection to deep luminescence signals and its potential use as an acceptor dopant, copper has been one the most studied impurities in ZnO. From experiment, copper incorporating on the Zn site (CuZn) is known to lead to an acceptor level residing near the conduction band of ZnO, making CuZn an exceedingly deep acceptor. CuZn in ZnO has also long been linked with broad 2.4 eV green luminescence (GL) signals. In this work we explore the electrical and optical properties of Cu in ZnO using density functional theory (DFT). Due to the limitations of traditional forms of DFT, an accurate theoretical description of the electrical and optical properties of such deep centers has been difficult to achieve. Here we employ a screened hybrid density functional (HSE) to calculate the properties of Cu in ZnO. We determine the thermodynamic transition levels associated with CuZn in ZnO as well as the associated luminescence lineshapes of characteristic optical transitions. We find that HSE-calculated optical transitions are in close agreement with experimental studies. This work was supported in part by NSF and by ARO.

Conductive nanogel-interfaced neural microelectrode arrays with electrically controlled in-situ delivery of manganese ions enabling high-resolution MEMRI for synchronous neural tracing with deep brain stimulation.

PubMed

Huang, Wei-Chen; Lo, Yu-Chih; Chu, Chao-Yi; Lai, Hsin-Yi; Chen, You-Yin; Chen, San-Yuan

2017-04-01

Chronic brain stimulation has become a promising physical therapy with increased efficacy and efficiency in the treatment of neurodegenerative diseases. The application of deep brain electrical stimulation (DBS) combined with manganese-enhanced magnetic resonance imaging (MEMRI) provides an unbiased representation of the functional anatomy, which shows the communication between areas of the brain responding to the therapy. However, it is challenging for the current system to provide a real-time high-resolution image because the incorporated MnCl 2 solution through microinjection usually results in image blurring or toxicity due to the uncontrollable diffusion of Mn 2+ . In this study, we developed a new type of conductive nanogel-based neural interface composed of amphiphilic chitosan-modified poly(3,4 -ethylenedioxythiophene) (PMSDT) that can exhibit biomimic structural/mechanical properties and ionic/electrical conductivity comparable to that of Au. More importantly, the PMSDT enables metal-ligand bonding with Mn 2+ ions, so that the system can release Mn 2+ ions rather than MnCl 2 solution directly and precisely controlled by electrical stimulation (ES) to achieve real-time high-resolution MEMRI. With the integration of PMSDT nanogel-based coating in polyimide-based microelectrode arrays, the post-implantation DBS enables frequency-dependent MR imaging in vivo, as well as small focal imaging in response to channel site-specific stimulation on the implant. The MR imaging of the implanted brain treated with 5-min electrical stimulation showed a thalamocortical neuronal pathway after 36 h, confirming the effective activation of a downstream neuronal circuit following DBS. By eliminating the susceptibility to artifact and toxicity, this system, in combination with a MR-compatible implant and a bio-compliant neural interface, provides a harmless and synchronic functional anatomy for DBS. The study demonstrates a model of MEMRI-functionalized DBS based on functional neural interface engineering and controllable delivery technology, which can be utilized in more detailed exploration of the functional anatomy in the treatment of neurodegenerative diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

Parallel Radiofrequency Transmission for the Reduction of Heating in Deep Brain Stimulation Leads at 3T

NASA Astrophysics Data System (ADS)

McElcheran, Clare

Deep Brain Stimulation (DBS) is increasingly used to treat a variety of brain diseases by sending electrical impulses to deep brain nuclei through long, electrically conductive leads. Magnetic resonance imaging (MRI) of patients pre- and post-implantation is desirable to target and position the implant, to evaluate possible side-effects and to examine DBS patients who have other health conditions. Although MRI is the preferred modality for pre-operative planning, MRI post-implantation is limited due to the risk of high local power deposition, and therefore tissue heating, at the tip of the lead. The localized power deposition arises from currents induced in the leads caused by coupling with the radiofrequency (RF) transmission field during imaging. In this thesis, parallel RF transmission (pTx) is used to tailor the RF electric field to suppress coupling effects. Three pTx coil configurations with 2-elements, 4-elements, and 8-elements, respectively, were investigated. Optimal input voltages to minimize coupling, while maintaining RF magnetic field homogeneity, were determined using a Nelder-Mead optimization algorithm. Resulting electric and magnetic fields were compared to that of a 16-rung birdcage coil. Experimental validation was performed with a custom-built 4-element pTx coil. Three cases were investigated to develop and evaluate this technique. First, a Proof-of-Concept study was performed to investigate the case of a simple, uniform cylindrical phantom with a straight, perfectly conducting wire. Second, a heterogeneous subject with bilateral, curved implanted wires was investigated. Finally, the third case investigated realistic patient lead-trajectories obtained from intra-operative CT scans. In all three cases, specific absorption rate (SAR), a metric used to quantify power deposition which results in heating, was reduced by over 90%. Maximal reduction in SAR was obtained with the 8-element pTx coil. Magnetic field homogeneity was comparable to the birdcage coil for the 4- and 8-element pTx configurations. Although further research is required before clinical implementation, these initial results suggest that the concept of optimizing pTx to reduce DBS heating effects holds considerable promise.

The effects of deep level traps on the electrical properties of semi-insulating CdZnTe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zha, Gangqiang; Yang, Jian; Xu, Lingyan

2014-01-28

Deep level traps have considerable effects on the electrical properties and radiation detection performance of high resistivity CdZnTe. A deep-trap model for high resistivity CdZnTe was proposed in this paper. The high resistivity mechanism and the electrical properties were analyzed based on this model. High resistivity CdZnTe with high trap ionization energy E{sub t} can withstand high bias voltages. The leakage current is dependent on both the deep traps and the shallow impurities. The performance of a CdZnTe radiation detector will deteriorate at low temperatures, and the way in which sub-bandgap light excitation could improve the low temperature performance canmore » be explained using the deep trap model.« less

Interpretation of Schlumberger DC resistivity data from Gibson Dome-Lockhart Basin study area, San Juan County, Utah

USGS Publications Warehouse

Watts, R.D.

1982-01-01

A Schlumberger dc resistivity survey of the Gibson Dome-Lockhart Basin area, San Juan County, Utah, has revealed the following electrical characteristics of the area: (1) the area between the northern part of Davis Canyon and Gibson Dome is electrically quite uniform and resistive at the depth of the Pennsylvanian evaporite deposits, (2) there is a deep conductive anomaly at Horsehead Rock, and (3) there are several shallow and deep electrical anomalies in the vicinity of the Lockhart fault system. No adverse indicators were found for nuclear waste repository siting south of Indian Creek, but additional soundings should be made to increase data density and to extend the survey area southward. The Lockhart fault system appears to have triggered salt dissolution or flow outside the limits of Lockhart Basin; further geophysical work and drilling will be required to understand the origin of the Lockhart Basin structure and its present state of activity. This problem is important because geologic processes that lead to enlargement of the Lockhart Basin structure or to development of similar structures would threaten the integrity of a repository in the Gibson Dome area.

Effects of electrode gap and electric current on chlorine generation of electrolyzed deep ocean water.

PubMed

Hsu, Guoo-Shyng Wang; Hsu, Shun-Yao

2018-04-01

Electrolyzed water is a sustainable disinfectant, which can comply with food safety regulations and is environmental friendly. A two-factor central composite design was adopted for studying the effects of electrode gap and electric current on chlorine generation efficiency of electrolyzed deep ocean water. Deep ocean water was electrolyzed in a glass electrolyzing cell equipped with platinum-plated titanium anode and cathode in a constant-current operation mode. Results showed that current density, chlorine concentration, and electrolyte temperature increased with electric current, while electric efficiency decreased with electric current and electrode gap. An electrode gap of less than 11.7 mm, and a low electric current appeared to be a more energy efficient design and operation condition for the electrolysis system. Copyright © 2017. Published by Elsevier B.V.

Electrical and Optical Studies of Deep Levels in Nominally Undoped Thallium Bromide

NASA Astrophysics Data System (ADS)

Smith, Holland M.; Haegel, Nancy M.; Phillips, David J.; Cirignano, Leonard; Ciampi, Guido; Kim, Hadong; Chrzan, Daryl C.; Haller, Eugene E.

2014-02-01

Photo-induced conductivity transient spectroscopy (PICTS) and cathodoluminescence (CL) measurements were performed on nominally undoped detector grade samples of TlBr. In PICTS measurements, nine traps were detected in the temperature range 80-250 K using four-gate analysis. Five of the traps are tentatively identified as electron traps, and four as hole traps. CL measurements yielded two broad peaks common to all samples and most likely associated with defects. Correlations between the optically and electrically detected deep levels are considered. Above 250 K, the photoconductivity transients measured in the PICTS experiments exhibited anomalous transient behavior, indicated by non-monotonic slope variations as a function of time. The origin of the transients is under further investigation, but their presence precludes the accurate determination of trap parameters in TlBr above 250 K with traditional PICTS analysis. Their discovery was made possible by the use of a PICTS system that records whole photoconductivity transients, as opposed to reduced and processed signals.

Aquifer Recharge Estimation In Unsaturated Porous Rock Using Darcian And Geophysical Methods.

NASA Astrophysics Data System (ADS)

Nimmo, J. R.; De Carlo, L.; Masciale, R.; Turturro, A. C.; Perkins, K. S.; Caputo, M. C.

2016-12-01

Within the unsaturated zone a constant downward gravity-driven flux of water commonly exists at depths ranging from a few meters to tens of meters depending on climate, medium, and vegetation. In this case a steady-state application of Darcy's law can provide recharge rate estimates.We have applied an integrated approach that combines field geophysical measurements with laboratory hydraulic property measurements on core samples to produce accurate estimates of steady-state aquifer recharge, or, in cases where episodic recharge also occurs, the steady component of recharge. The method requires (1) measurement of the water content existing in the deep unsaturated zone at the location of a core sample retrieved for lab measurements, and (2) measurement of the core sample's unsaturated hydraulic conductivity over a range of water content that includes the value measured in situ. Both types of measurements must be done with high accuracy. Darcy's law applied with the measured unsaturated hydraulic conductivity and gravitational driving force provides recharge estimates.Aquifer recharge was estimated using Darcian and geophysical methods at a deep porous rock (calcarenite) experimental site in Canosa, southern Italy. Electrical Resistivity Tomography (ERT) and Vertical Electrical Sounding (VES) profiles were collected from the land surface to water table to provide data for Darcian recharge estimation. Volumetric water content was estimated from resistivity profiles using a laboratory-derived calibration function based on Archie's law for rock samples from the experimental site, where electrical conductivity of the rock was related to the porosity and water saturation. Multiple-depth core samples were evaluated using the Quasi-Steady Centrifuge (QSC) method to obtain hydraulic conductivity (K), matric potential (ψ), and water content (θ) estimates within this profile. Laboratory-determined unsaturated hydraulic conductivity ranged from 3.90 x 10-9 to 1.02 x 10-5 m/s over a volumetric water content range from 0.1938 to 0.4311 m3/m3. Using these measured properties, the water content estimated from geophysical measurements has been used to identify the unsaturated hydraulic conductivity indicative of the steady component of the aquifer recharge rate at Canosa.

Referred pain and cutaneous responses from deep tissue electrical pain stimulation in the groin.

PubMed

Aasvang, E K; Werner, M U; Kehlet, H

2015-08-01

Persistent postherniotomy pain is located around the scar and external inguinal ring and is often described as deep rather than cutaneous, with frequent complaints of pain in adjacent areas. Whether this pain is due to local pathology or referred/projected pain is unknown, hindering mechanism-based treatment. Deep tissue electrical pain stimulation by needle electrodes in the right groin (rectus muscle, ilioinguinal/iliohypogastric nerve and perispermatic cord) was combined with assessment of referred/projected pain and the cutaneous heat pain threshold (HPT) at three prespecified areas (both groins and the lower right arm) in 19 healthy subjects. The assessment was repeated 10 days later to assess the reproducibility of individual responses. Deep electrical stimulation elicited pain at the stimulation site in all subjects, and in 15 subjects, pain from areas outside the stimulation area was reported, with 90-100% having the same response on both days, depending on the location. Deep pain stimulation significantly increased the cutaneous HPT (P<0.014). Individual HPT responses before and during deep electrical pain stimulation were significantly correlated (ρ>0.474, P≤0.040) at the two test days for the majority of test areas. Our results corroborate a systematic relationship between deep pain and changes in cutaneous nociception. The individual referred/projected pain patterns and cutaneous responses are variable, but reproducible, supporting individual differences in anatomy and sensory processing. Future studies investigating the responses to deep tissue electrical stimulation in persistent postherniotomy pain patients may advance our understanding of underlying pathophysiological mechanisms and strategies for treatment and prevention. ClinicalTrials.gov (NCT01701427). © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Three dimensional amorphous silicon/microcrystalline silicon solar cells

DOEpatents

Kaschmitter, James L.

1996-01-01

Three dimensional deep contact amorphous silicon/microcrystalline silicon (a-Si/.mu.c-Si) solar cells which use deep (high aspect ratio) p and n contacts to create high electric fields within the carrier collection volume material of the cell. The deep contacts are fabricated using repetitive pulsed laser doping so as to create the high aspect p and n contacts. By the provision of the deep contacts which penetrate the electric field deep into the material where the high strength of the field can collect many of the carriers, thereby resulting in a high efficiency solar cell.

Three dimensional amorphous silicon/microcrystalline silicon solar cells

DOEpatents

Kaschmitter, J.L.

1996-07-23

Three dimensional deep contact amorphous silicon/microcrystalline silicon (a-Si/{micro}c-Si) solar cells are disclosed which use deep (high aspect ratio) p and n contacts to create high electric fields within the carrier collection volume material of the cell. The deep contacts are fabricated using repetitive pulsed laser doping so as to create the high aspect p and n contacts. By the provision of the deep contacts which penetrate the electric field deep into the material where the high strength of the field can collect many of the carriers, thereby resulting in a high efficiency solar cell. 4 figs.

Modulation of the electrical properties in amorphous indium-gallium zinc-oxide semiconductor films using hydrogen incorporation

NASA Astrophysics Data System (ADS)

Song, Aeran; Park, Hyun-Woo; Chung, Kwun-Bum; Rim, You Seung; Son, Kyoung Seok; Lim, Jun Hyung; Chu, Hye Yong

2017-12-01

The electrical properties of amorphous-indium-gallium-zinc-oxide (a-IGZO) thin films were investigated after thermal annealing and plasma treatment under different gas conditions. The electrical resistivity of a-IGZO thin films post-treated in a hydrogen ambient were lower than those without treatment and those annealed in air, regardless of the methods used for both thermal annealing and plasma treatment. The electrical properties can be explained by the quantity of hydrogen incorporated into the samples and the changes in the electronic structure in terms of the chemical bonding states, the distribution of the near-conduction-band unoccupied states, and the band alignment. As a result, the carrier concentrations of the hydrogen treated a-IGZO thin films increased, while the mobility decreased, due to the increase in the oxygen vacancies from the occurrence of unoccupied states in both shallow and deep levels.

Processing-Induced Electrically Active Defects in Black Silicon Nanowire Devices.

PubMed

Carapezzi, Stefania; Castaldini, Antonio; Mancarella, Fulvio; Poggi, Antonella; Cavallini, Anna

2016-04-27

Silicon nanowires (Si NWs) are widely investigated nowadays for implementation in advanced energy conversion and storage devices, as well as many other possible applications. Black silicon (BSi)-NWs are dry etched NWs that merge the advantages related to low-dimensionality with the special industrial appeal connected to deep reactive ion etching (RIE). In fact, RIE is a well established technique in microelectronics manufacturing. However, RIE processing could affect the electrical properties of BSi-NWs by introducing deep states into their forbidden gap. This work applies deep level transient spectroscopy (DLTS) to identify electrically active deep levels and the associated defects in dry etched Si NW arrays. Besides, the successful fitting of DLTS spectra of BSi-NWs-based Schottky barrier diodes is an experimental confirmation that the same theoretical framework of dynamic electronic behavior of deep levels applies in bulk as well as in low dimensional structures like NWs, when quantum confinement conditions do not occur. This has been validated for deep levels associated with simple pointlike defects as well as for deep levels associated with defects with richer structures, whose dynamic electronic behavior implies a more complex picture.

Study on temperature distribution effect on internal charging by computer simulation

NASA Astrophysics Data System (ADS)

Yi, Zhong

2016-07-01

Internal charging (or deep dielectric charging) is a great threaten to spacecraft. Dielectric conductivity is an important parameter for internal charging and it is sensitive to temperature. Considering the exposed dielectric outside a spacecraft may experience a relatively large temperature range, temperature effect can't be ignored in internal charging assessment. We can see some reporters on techniques of computer simulation of internal charging, but the temperature effect has not been taken into accounts. In this paper, we realize the internal charging simulation with consideration of temperature distribution inside the dielectric. Geant4 is used for charge transportation, and a numerical method is proposed for solving the current reservation equation. The conductivity dependences on temperature, radiation dose rate and intense electric field are considered. Compared to the case of uniform temperature, the internal charging with temperature distribution is more complicated. Results show that temperature distribution can cause electric field distortion within the dielectric. This distortion refers to locally considerable enlargement of electric field. It usually corresponds to the peak electric field which is critical for dielectric breakdown judgment. The peak electric field can emerge inside the dielectric, or appear on the boundary. This improvement of internal charging simulation is beneficial for the assessment of internal charging under multiple factors.

Electrical characterization and comparison of CIGS solar cells made with different structures and fabrication techniques

DOE PAGES

Garris, Rebekah L.; Johnston, Steven; Li, Jian V.; ...

2017-08-31

In a previous study, we reported on Cu(In,Ga)Se2-based (CIGS) solar cell samples collected from different research laboratories and industrial companies with the purpose of understanding the range of CIGS materials that can lead to high-quality and high-efficiency solar panels. Here, we report on electrical measurements of those same samples. Electron-beam induced current and time-resolved photoluminescence (TRPL) gave insights about the collection probability and the lifetime of carriers generated in each absorber. Capacitance and drive-level capacitance profiling revealed nonuniformity in carrier-density profiles. Admittance spectroscopy revealed small activation energies (= 0.03 eV) indicative of the inversion strength, larger activation energies (> 0.1more » eV) reflective of thermal activation of absorber conductivity and a deeper defect level. Deep-level transient spectroscopy (DLTS) probed deep hole-trapping defects and showed that all samples in this study had a majority-carrier defect with activation energy between 0.3 eV and 0.9 eV. Optical-DLTS revealed deep electron-trapping defects in several of the CIGS samples. This work focused on revealing similarities and differences between high-quality CIGS solar cells made with various structures and fabrication techniques.« less

Electrical characterization and comparison of CIGS solar cells made with different structures and fabrication techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garris, Rebekah L.; Johnston, Steven; Li, Jian V.

In a previous study, we reported on Cu(In,Ga)Se2-based (CIGS) solar cell samples collected from different research laboratories and industrial companies with the purpose of understanding the range of CIGS materials that can lead to high-quality and high-efficiency solar panels. Here, we report on electrical measurements of those same samples. Electron-beam induced current and time-resolved photoluminescence (TRPL) gave insights about the collection probability and the lifetime of carriers generated in each absorber. Capacitance and drive-level capacitance profiling revealed nonuniformity in carrier-density profiles. Admittance spectroscopy revealed small activation energies (= 0.03 eV) indicative of the inversion strength, larger activation energies (> 0.1more » eV) reflective of thermal activation of absorber conductivity and a deeper defect level. Deep-level transient spectroscopy (DLTS) probed deep hole-trapping defects and showed that all samples in this study had a majority-carrier defect with activation energy between 0.3 eV and 0.9 eV. Optical-DLTS revealed deep electron-trapping defects in several of the CIGS samples. This work focused on revealing similarities and differences between high-quality CIGS solar cells made with various structures and fabrication techniques.« less

EL2 deep-level transient study in semi-insulating GaAs using positron-lifetime spectroscopy

NASA Astrophysics Data System (ADS)

Shan, Y. Y.; Ling, C. C.; Deng, A. H.; Panda, B. K.; Beling, C. D.; Fung, S.

1997-03-01

Positron lifetime measurements performed on Au/GaAs samples at room temperature with an applied square-wave ac bias show a frequency dependent interface related lifetime intensity that peaks around 0.4 Hz. The observation is explained by the ionization of the deep-donor level EL2 to EL2+ in the GaAs region adjacent to the Au/GaAs interface, causing a transient electric field to be experienced by positrons drifting towards the interface. Without resorting to temperature scanning or any Arrhenius plot the EL2 donor level is found to be located 0.80+/-0.01+/-0.05 eV below the conduction-band minimum, where the first error estimate is statistical and the second systematic. The result suggests positron annihilation may, in some instances, act as an alternative to capacitance transient spectroscopies in characterizing deep levels in both semiconductors and semi-insulators.

Long distance seawater intrusion through a karst conduit network in the Woodville Karst Plain, Florida

NASA Astrophysics Data System (ADS)

Xu, Zexuan; Bassett, Seth Willis; Hu, Bill; Dyer, Scott Barrett

2016-08-01

Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electrical conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and traveling 11 miles against the prevailing regional hydraulic gradient from from Spring Creek Spring Complex (SCSC), a group of submarine springs at the Gulf Coast. A geochemical analysis of samples from the spring vent rules out anthropogenic contamination and upwelling regional recharge from the deep aquifer as sources of the rising conductivity. The interpretation is supported by the conceptual model established by prior researchers working to characterize the study area. This paper documents the first and longest case of seawater intrusion in the WKP, and also indicates significant possibility of seawater contamination through subsurface conduit networks in a coastal karst aquifer.

Field observations of extended seawater intrusion through subsurface karst conduit networks at Wakulla Spring in the Woodville Karst Plain, Florida

NASA Astrophysics Data System (ADS)

Xu, Z.; Bassett, S.; Hu, B. X.; Dyer, S.

2016-12-01

Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electric conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and traveling 14 miles against the prevailing regional hydraulic gradient from from Spring Creek Spring Complex (SCSC), a group of submarine springs at the Gulf Coast. A geochemical analysis of samples from the spring vent rules out anthropogenic contamination and upwelling regional recharge from the deep aquifer as sources of the rising conductivity. The interpretation is supported by the conceptual model established by prior researchers working to characterize the study area. This abstract documented the first and longest case of seawater intrusion in the WKP, and also indicates significant possibility of seawater contamination through subsurface conduit networks in a coastal karst aquifer.

Long distance seawater intrusion through a karst conduit network in the Woodville Karst Plain, Florida.

PubMed

Xu, Zexuan; Bassett, Seth Willis; Hu, Bill; Dyer, Scott Barrett

2016-08-25

Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electrical conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and traveling 11 miles against the prevailing regional hydraulic gradient from from Spring Creek Spring Complex (SCSC), a group of submarine springs at the Gulf Coast. A geochemical analysis of samples from the spring vent rules out anthropogenic contamination and upwelling regional recharge from the deep aquifer as sources of the rising conductivity. The interpretation is supported by the conceptual model established by prior researchers working to characterize the study area. This paper documents the first and longest case of seawater intrusion in the WKP, and also indicates significant possibility of seawater contamination through subsurface conduit networks in a coastal karst aquifer.

Long distance seawater intrusion through a karst conduit network in the Woodville Karst Plain, Florida

PubMed Central

Xu, Zexuan; Bassett, Seth Willis; Hu, Bill; Dyer, Scott Barrett

2016-01-01

Five periods of increased electrical conductivity have been found in the karst conduits supplying one of the largest first magnitude springs in Florida with water. Numerous well-developed conduit networks are distributed in the Woodville Karst Plain (WKP), Florida and connected to the Gulf of Mexico. A composite analysis of precipitation and electrical conductivity data provides strong evidence that the increases in conductivity are directly tied to seawater intrusion moving inland and traveling 11 miles against the prevailing regional hydraulic gradient from from Spring Creek Spring Complex (SCSC), a group of submarine springs at the Gulf Coast. A geochemical analysis of samples from the spring vent rules out anthropogenic contamination and upwelling regional recharge from the deep aquifer as sources of the rising conductivity. The interpretation is supported by the conceptual model established by prior researchers working to characterize the study area. This paper documents the first and longest case of seawater intrusion in the WKP, and also indicates significant possibility of seawater contamination through subsurface conduit networks in a coastal karst aquifer. PMID:27557803

Imaging the magmatic system of Mono Basin, California with magnetotellurics in three--dimensions

USGS Publications Warehouse

Peacock, Jared R.; Mangan, Margaret T.; McPhee, Darcy K.; Ponce, David A.

2015-01-01

A three–dimensional (3D) electrical resistivity model of Mono Basin in eastern California unveils a complex subsurface filled with zones of partial melt, fluid–filled fracture networks, cold plutons, and regional faults. In 2013, 62 broadband magnetotelluric (MT) stations were collected in an array around southeastern Mono Basin from which a 3D electrical resistivity model was created with a resolvable depth of 35 km. Multiple robust electrical resistivity features were found that correlate with existing geophysical observations. The most robust features are two 300 ± 50 km3 near-vertical conductive bodies (3–10 Ω·m) that underlie the southeast and north-eastern margin of Mono Craters below 10 km depth. These features are interpreted as magmatic crystal–melt mush zones of 15 ± 5% interstitial melt surrounded by hydrothermal fluids and are likely sources for Holocene eruptions. Two conductive east–dipping structures appear to connect each magma source region to the surface. A conductive arc–like structure (< 0.9 Ω·m) links the northernmost mush column at 10 km depth to just below vents near Panum Crater, where the high conductivity suggests the presence of hydrothermal fluids. The connection from the southernmost mush column at 10 km depth to below South Coulée is less obvious with higher resistivity (200 Ω·m) suggestive of a cooled connection. A third, less constrained conductive feature (4–10 Ω·m) 15 km deep extending to 35 km is located west of Mono Craters near the eastern front of the Sierra Nevada escarpment, and is coincident with a zone of sporadic, long–period earthquakes that are characteristic of a fluid-filled (magmatic or metamorphic) fracture network. A resistive feature (103–105 Ω·m) located under Aeolian Buttes contains a deep root down to 25 km. The eastern edge of this resistor appears to structurally control the arcuate shape of Mono Craters. These observations have been combined to form a new conceptual model of the magmatic system beneath Mono Craters to a depth of 30 km.

Resolving the deep electrical resistivity structure at Central Pontides, Northern Turkey by three-dimensional magnetotelluric modeling

NASA Astrophysics Data System (ADS)

Özaydın, Sinan; Bülent Tank, Sabri; Karaş, Mustafa; Sandvol, Eric

2017-04-01

Wide-band magnetotelluric (MT) (360 Hz - 1860 sec) data were acquired at 25 sites along a north - south aligned profile cutting across the Central Pontides, which are made up of highly metamorphosed formations and their tectonic boundaries including: a Lower Cretaceous-aged turbidite sequence, Central Pontides Metamorphic Supercomplex (CPMS), North Anatolian Fault Zone (NAFZ) and Izmir-Ankara-Erzincan Suture Zone (IAESZ). Dimensionality analyses over all observation points demonstrated high electrical anisotropy, which indicates complex geological and tectonic structures. This dimensional complexity and presence of the electrically conductive Black Sea augmented the requirement for a three-dimensional analysis. Inverse modeling routines, ModEM (Egbert and Kelbert, 2012) and WSINV3DMT (Siripunvaraporn et al., 2005) were utilized to reveal the geo-electrical implications over this unusually complicated region. Interpretations of the resultant models are summarized as follows: (i) Çangaldaǧ and Domuzdaǧ complexes appear as highly resistive bodies bounded by north dipping faults. (ii) Highly conductive Tosya Basin sediments overlain the ophiolitic materials as a thin cover located at the south of the NAFZ. (iii) North Anatolian Fault and some auxiliary faults within the system exhibit conductive-resistive interfaces that reach to lower crustal levels. (iv) IAESZ is a clear feature marked by the resistivity contrast between NAFZ-related sedimentary basins and Neo-Tethyan ophiolites.

Transparent conductive oxide films mixed with gallium oxide nanoparticle/single-walled carbon nanotube layer for deep ultraviolet light-emitting diodes

PubMed Central

2013-01-01

We propose a transparent conductive oxide electrode scheme of gallium oxide nanoparticle mixed with a single-walled carbon nanotube (Ga2O3 NP/SWNT) layer for deep ultraviolet light-emitting diodes using spin and dipping methods. We investigated the electrical, optical and morphological properties of the Ga2O3 NP/SWNT layers by increasing the thickness of SWNTs via multiple dipping processes. Compared with the undoped Ga2O3 films (current level 9.9 × 10-9 A @ 1 V, transmittance 68% @ 280 nm), the current level flowing in the Ga2O3 NP/SWNT increased by approximately 4 × 105 times and the transmittance improved by 9% after 15 times dip-coating (current level 4 × 10-4 A at 1 V; transmittance 77.0% at 280 nm). These improvements result from both native high transparency of Ga2O3 NPs and high conductivity and effective current spreading of SWNTs. PMID:24295342

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renno, Nilton O.; Ruf, Christopher S., E-mail: renno@alum.mit.edu

Ruf et al. used the Deep Space Network (DSN) to search for the emission of non-thermal radiation by martian dust storms, theoretically predicted by Renno et al. They detected the emission of non-thermal radiation that they were searching for, but were surprised that it contained spectral peaks suggesting modulation at various frequencies and their harmonics. Ruf et al. hypothesized that the emission of non-thermal radiation was caused by electric discharges in a deep convective dust storm, modulated by Schumann resonances (SRs). Anderson et al. used the Allen Telescope Array (ATA) to search for similar emissions. They stated that they foundmore » only radio frequency interference (RFI) during their search for non-thermal emission by martian dust storms and implicitly suggested that the signal detected by Ruf et al. was also RFI. However, their search was not conducted during the dust storm season when deep convective storms are most likely to occur. Here, we show that the ubiquitous dust devils and small-scale dust storms that were instead likely present during their observations are too shallow to excite SRs and produce the signals detected by Ruf et al. We also show that the spectral and temporal behavior of the signals detected by Anderson et al. corroborates the idea that they originated from man-made pulse-modulated telecommunication signals rather than martian electric discharges. In contrast, an identical presentation of the signals detected by Ruf et al. demonstrates that they do not resemble man-made signals. The presentation indicates that the DSN signals were consistent with modulation by martian SRs, as originally hypothesized by Ruf et al. We propose that a more comprehensive search for electrostatic discharges be conducted with either the ATA or DSN during a future martian dust storm season to test the hypothesis proposed by Ruf et al.« less

Offshore Floating Wind Turbine-driven Deep Sea Water Pumping for Combined Electrical Power and District Cooling

NASA Astrophysics Data System (ADS)

Sant, T.; Buhagiar, D.; Farrugia, R. N.

2014-06-01

A new concept utilising floating wind turbines to exploit the low temperatures of deep sea water for space cooling in buildings is presented. The approach is based on offshore hydraulic wind turbines pumping pressurised deep sea water to a centralised plant consisting of a hydro-electric power system coupled to a large-scale sea water-cooled air conditioning (AC) unit of an urban district cooling network. In order to investigate the potential advantages of this new concept over conventional technologies, a simplified model for performance simulation of a vapour compression AC unit was applied independently to three different systems, with the AC unit operating with (1) a constant flow of sea surface water, (2) a constant flow of sea water consisting of a mixture of surface sea water and deep sea water delivered by a single offshore hydraulic wind turbine and (3) an intermittent flow of deep sea water pumped by a single offshore hydraulic wind turbine. The analysis was based on one year of wind and ambient temperature data for the Central Mediterranean that is known for its deep waters, warm climate and relatively low wind speeds. The study confirmed that while the present concept is less efficient than conventional turbines utilising grid-connected electrical generators, a significant portion of the losses associated with the hydraulic transmission through the pipeline are offset by the extraction of cool deep sea water which reduces the electricity consumption of urban air-conditioning units.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parker, D.; Sutherland, K.; Chasar, D.

The U.S. Department of Energy (DOE) Building America program, in collaboration with Florida Power and Light (FPL), conducted a phased residential energy-efficiency retrofit program. This research sought to establish impacts on annual energy and peak energy reductions from the technologies applied at two levels of retrofit - shallow and deep, with savings levels approaching the Building America program goals of reducing whole-house energy use by 40%. Under the Phased Deep Retrofit (PDR) project, we have installed phased, energy-efficiency retrofits in a sample of 56 existing, all-electric homes. End-use savings and economic evaluation results from the phased measure packages and singlemore » measures are summarized in this report. Project results will be of interest to utility program designers, weatherization evaluators, and the housing remodel industry. Shallow retrofits were conducted in all homes from March to June 2013. The measures for this phase were chosen based on ease of installation, targeting lighting (CFLs and LED lamps), domestic hot water (wraps and showerheads), refrigeration (cleaning of coils), pool pump (reduction of operating hours), and the home entertainment center (smart plugs). Deep retrofits were conducted on a subset of ten PDR homes from May 2013 through March 2014. Measures included new air source heat pumps, duct repair, ceiling insulation, heat pump water heaters, variable speed pool pumps and learning thermostats. Major appliances such as refrigerators and dishwashers were replaced where they were old and inefficient.« less

Deep-towed CSEM survey of gas hydrates in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Kannberg, P.; Constable, S.

2017-12-01

Controlled source electromagnetic (CSEM) surveys are increasingly being used to remotely detect hydrate deposits in seafloor sediments. CSEM methods are sensitive to sediment pore space resistivity, such as when electrically resistive hydrate displaces the electrically conductive pore fluid, increasing the bulk resistivity of the sediment. In July 2017, a two-week research cruise using an upgraded and expanded "Vulcan" towed receiver system collected over 250 line km of data at four sites in the Gulf of Mexico (GoM) thought to have hydrate bearing sediments. Hydrate bearing horizons at the survey sites ranged from 400-700 m below seafloor. Modeling suggested an array with source receiver offsets of up to 1600 m would be needed to properly image the deep hydrate. A deep towed electromagnetic transmitter outputting 270 Amps was towed 100 m above seafloor. Six Vulcan receivers, each recording three-axis electric field data, were towed at 200 m intervals from 600-1600 m behind the transmitter. The four sites surveyed, Walker Ridge 313, Orca Basin, Mad Dog, and Green Canyon 955, are associated with the upcoming GOM^2 coring operation scheduled for 2020. Wells at WR313 and GC955 were logged as part of a joint industry drilling project in 2009 and will be used to ground truth our inversion results. In 2008, WR313 and GC955 were surveyed using traditional CSEM seafloor receivers, accompanied by a single prototype Vulcan towed receiver. This prior survey will allow comparison of results from a seafloor receiver survey with those from a towed receiver survey. Seismic data has been collected at all the sites, which will be used to constrain inversions. In addition to the four hydrate sites surveyed, two lines were towed over Green Knoll, a deep-water salt dome located between Mad Dog and GC955. Presented here are initial results from our recent cruise.

Electronic Components and Circuits for Extreme Temperature Environments

NASA Technical Reports Server (NTRS)

Patterson, Richard L.; Hammoud, Ahmad; Dickman, John E.; Gerber, Scott

2003-01-01

Planetary exploration missions and deep space probes require electrical power management and control systems that are capable of efficient and reliable operation in very low temperature environments. Presently, spacecraft operating in the cold environment of deep space carry a large number of radioisotope heating units in order to maintain the surrounding temperature of the on-board electronics at approximately 20 C. Electronics capable of operation at cryogenic temperatures will not only tolerate the hostile environment of deep space but also reduce system size and weight by eliminating or reducing the radioisotope heating units and their associate structures; thereby reducing system development as well as launch costs. In addition, power electronic circuits designed for operation at low temperatures are expected to result in more efficient systems than those at room temperature. This improvement results from better behavior and tolerance in the electrical and thermal properties of semiconductor and dielectric materials at low temperatures. The Low Temperature Electronics Program at the NASA Glenn Research Center focuses on research and development of electrical components, circuits, and systems suitable for applications in the aerospace environment and deep space exploration missions. Research is being conducted on devices and systems for reliable use down to cryogenic temperatures. Some of the commercial-off-the-shelf as well as developed components that are being characterized include switching devices, resistors, magnetics, and capacitors. Semiconductor devices and integrated circuits including digital-to-analog and analog-to-digital converters, DC/DC converters, operational amplifiers, and oscillators are also being investigated for potential use in low temperature applications. An overview of the NASA Glenn Research Center Low Temperature Electronic Program will be presented in this paper. A description of the low temperature test facilities along with selected data obtained through in-house component and circuit testing will also be discussed. Ongoing research activities that are being performed in collaboration with various organizations will also be presented.

Solid state convection models of lunar internal temperature

NASA Technical Reports Server (NTRS)

Schubert, G.; Young, R. E.; Cassen, P.

1975-01-01

Thermal models of the Moon were made which include cooling by subsolidus creep and consideration of the creep behavior of geologic material. Measurements from the Apollo program on seismic velocities, electrical conductivity of the Moon's interior, and heat flux at two locations were used in the calculations. Estimates of 1500 to 1600 K were calculated for the temperature, and one sextillion to ten sextillion sq cm/sec were calcualted for the viscosity of the deep lunar interior.

Deep electromagnetic sounding of the lithosphere in the eastern Baltic (fennoscandian) shield with high-power controlled sources and industrial power transmission lines (FENICS experiment)

NASA Astrophysics Data System (ADS)

Zhamaletdinov, A. A.; Shevtsov, A. N.; Korotkova, T. G.; Kopytenko, Yu. A.; Ismagilov, V. S.; Petrishev, M. S.; Efimov, B. V.; Barannik, M. B.; Kolobov, V. V.; Prokopchuk, P. I.; Smirnov, M. Yu.; Vagin, S. A.; Pertel, M. I.; Tereshchenko, E. D.; Vasil'Ev, A. N.; Grigoryev, V. F.; Gokhberg, M. B.; Trofimchik, V. I.; Yampolsky, Yu. M.; Koloskov, A. V.; Fedorov, A. V.; Korja, T.

2011-01-01

The paper addresses the technique and the first results of a unique experiment on the deep tensor frequency electromagnetic sounding, the Fennoscandian Electrical conductivity from results of sounding with Natural and Controlled Sources (FENICS). In the experiment, Energy-1 and Energy-2 generators with power of up to 200 kW and two mutually orthogonal industrial 109- and 120-km-long power transmission lines were used. The sounding frequency range was 0.1-200 Hz. The signals were measured in the Kola-Karelian region, in Finland, on Svalbard, and in Ukraine at distances up to 2150 km from the source. The parameters of electric conductivity in the lithosphere are studied down to depths on the order of 50-70 km. A strong lateral homogeneity (the one-dimensionality) of a geoelectric section of the Earth's crust is revealed below depths of 10-15 km. At the same time, a region with reduced transverse crustal resistivity spread over about 80 000 square kilometers is identified within the depth interval from 20 to 40 km. On the southeast the contour of the anomaly borders the zone of deepening of the Moho boundary down to 60 km in Central Finland. The results are compared with the AMT-MT sounding data and a geodynamic interpretation of the obtained information is carried out.

Joint Radioisotope Electric Propulsion Studies - Neptune System Explorer

NASA Technical Reports Server (NTRS)

Khan, M. Omair; Amini, Rashied; Ervin, Joan; Lang, Jared; Landau, Damon; Oleson, Steven; Spilker, Thomas; Strange, Nathan

2011-01-01

The Neptune System Explorer (NSE) mission concept study assessed opportunities to conduct Cassini-like science at Neptune with a radioisotope electric propulsion (REP) based spacecraft. REP is based on powering an electric propulsion (EP) engine with a radioisotope power source (RPS). The NSE study was commissioned under the Joint Radioisotope Electric Propulsion Studies (JREPS) project, which sought to determine the technical feasibility of flagship class REP applications. Within JREPS, special emphasis was given toward identifying tall technology tent poles, as well as recommending any new RPS technology developments that would be required for complicated REP missions. Based on the goals of JREPS, multiple RPS (e.g. thermoelectric and Stirling based RPS) and EP (e.g. Hall and ion engines) technology combinations were traded during the NSE study to determine the most favorable REP design architecture. Among the findings from the study was the need for >400We RPS systems, which was driven by EP operating powers and the requirement for a long-lived mission in the deep solar system. Additionally multiple development and implementation risks were identified for the NSE concept, as well as REP missions in general. Among the strengths of the NSE mission would be the benefits associated with RPS and EP use, such as long-term power (approx. 2-3kW) at Neptune and flexible trajectory options for achieving orbit or tours of the Neptune system. Although there are still multiple issues to mitigate, the NSE concept demonstrated distinct advantages associated with using REP for deep space flagship-class missions.

Numerical investigation of the interaction of positive streamers with bubbles floating on a liquid surface

NASA Astrophysics Data System (ADS)

Babaeva, Natalia Yu.; Naidis, George V.; Kushner, Mark J.

2016-09-01

Streamer discharges in air intersecting with liquids are being investigated to produce reactivity in the liquid. In this talk, we discuss results from a 2-d computational investigation of streamers in air intersecting an isolated liquid, air filled bubble floating on a liquid surface. The 15 mm diameter bubble is conducting water (ɛ /ɛ0 = 80 , σ = 7 . 5 ×10-4Ω-1cm-1) or transformer oil (ɛ /ɛ0 = 2 . 2 , σ = 1 . 5 ×10-13Ω-1cm-1). A needle electrode is positioned d =0-10 mm from the bubble center. With a water bubble (d =0) the streamer slides along the external surface but does not penetrate the bubble due to electric field screening by the conducting shell. If the electrode is shifted (d =3-10 mm) the streamer deviates from the vertical and adheres to the bubble. If the electrode is inserted inside the bubble, the streamer path depends on how deep the electrode penetrates. For shallow penetration, the streamer propagates along the inner surface of the bubble. For deep penetration the streamer takes the shortest path down through the gas. Due to the low conductivity of the oil bubble shell the electric field penetrates into the interior of the bubble. The streamer can then be re-initiated inside the bubble. Charge accumulation on both sides of the bubble shell and perforation of the shell will be also discussed. NYB, GVN supported by Russian Sci. Found. (14-12-01295). MJK by US Natl. Sci. Found. and Dept. of Energy.

On the physics of frequency-domain controlled source electromagnetics in shallow water. 1: isotropic conductivity

NASA Astrophysics Data System (ADS)

Chave, Alan D.; Everett, Mark E.; Mattsson, Johan; Boon, James; Midgley, Jonathan

2017-02-01

In recent years, marine controlled source electromagnetics (CSEM) has found increasing use in hydrocarbon exploration due to its ability to detect thin resistive zones beneath the seafloor. It is the purpose of this paper to evaluate the physics of CSEM for an ocean whose electrical thickness is comparable to or much thinner than that of the overburden using the in-line configuration through examination of the elliptically polarized seafloor electric field, the time-averaged energy flow depicted by the real part of the complex Poynting vector, energy dissipation through Joule heating and the Fréchet derivatives of the seafloor field with respect to the subseafloor conductivity that is assumed to be isotropic. The deep water (ocean layer electrically much thicker than the overburden) seafloor EM response for a model containing a resistive reservoir layer has a greater amplitude and reduced phase as a function of offset compared to that for a half-space, or a stronger and faster response. For an ocean whose electrical thickness is comparable to or much smaller than that of the overburden, the electric field displays a greater amplitude and reduced phase at small offsets, shifting to a stronger amplitude and increased phase at intermediate offsets and a weaker amplitude and enhanced phase at long offsets, or a stronger and faster response that first changes to stronger and slower, and then transitions to weaker and slower. These transitions can be understood by visualizing the energy flow throughout the structure caused by the competing influences of the dipole source and guided energy flow in the reservoir layer, and the air interaction caused by coupling of the entire subseafloor resistivity structure with the sea surface. A stronger and faster response occurs when guided energy flow is dominant, while a weaker and slower response occurs when the air interaction is dominant. However, at intermediate offsets for some models, the air interaction can partially or fully reverse the direction of energy flux in the reservoir layer toward rather than away from the source, resulting in a stronger and slower response. The Fréchet derivatives are dominated by preferential sensitivity to the reservoir layer conductivity for all water depths except at high frequencies, but also display a shift with offset from the galvanic to the inductive mode in the underburden and overburden due to the interplay of guided energy flow and the air interaction. This means that the sensitivity to the horizontal conductivity is almost as strong as to the vertical component in the shallow parts of the subsurface, and in fact is stronger than the vertical sensitivity deeper down. However, the sensitivity to horizontal conductivity is still weak compared to the vertical component within thin resistive regions. The horizontal sensitivity is gradually decreased when the water becomes deep. These observations in part explain the success of shallow towed CSEM using only measurements of the in-line component of the electric field.

Geophysical evaluation of the Success Dam foundation, Porterville, California

USGS Publications Warehouse

Hunter, L.E.; Powers, M.H.; Haines, S.; Asch, T.; Burton, B.L.; Serafini, D.C.

2006-01-01

Success Dam is a zonedearth fill embankment located near Porterville, CA. Studies of Success Dam by the recent Dam Safety Assurance Program (DSAP) have demonstrated the potential for seismic instability and large deformation of the dam due to relatively low levels of earthquake shaking. The U.S. Army Corps of Engineers conducted several phases of investigations to determine the properties of the dam and its underlying foundation. Detailed engineering studies have been applied using a large number of analytical techniques to estimate the response of the dam and foundation system when subjected to earthquake loading. Although a large amount of data have been acquired, most are 'point' data from borings and results have to be extrapolated between the borings. Geophysical techniques were applied to image the subsurface to provide a better understanding of the spatial distribution of key units that potentially impact the stability. Geophysical investigations employing seismic refraction tomography, direct current (DC) resistivity, audio magnetotellurics (AMT) and self-potential (SP) were conducted across the location of the foundation of a new dam proposed to replace the existing one. Depth to bedrock and the occurrence of beds potentially susceptible to liquefaction were the focus of the investigations. Seismic refraction tomography offers a deep investigation of the foundation region and looks at compressional and shear properties of the material. Whereas resistivity surveys determines conductivity relationships in the shallow subsurface and can produce a relatively high-resolution image of geological units with different electrical properties. AMT was applied because it has the potential to look considerably deeper than the other methods, is useful for confirming depth to bedrock, and can be useful in identifying deep seated faults. SP is a passive electrical method that measures the electrical streaming potential in the subsurface that responds to the movement of ground water. SP surveys were conducted at low pool and high pool conditions in order to look for evidence of seepage below the existing dam. In this paper, we summarize these techniques, present their results at Success Dam, and discuss general application of these techniques for investigating dams and their foundations.

Electromagnetic studies in the Fennoscandian Shield—electrical conductivity of Precambrian crust

NASA Astrophysics Data System (ADS)

Korja, T.; Hjelt, S.-E.

1993-12-01

Electromagnetic (EM) investigations of the 1980s in the Fennoscandian (Baltic) Shield produced an unique and unified EM data set. Studies include regional investigations by the magnetovariational (MV) method with large lateral sampling distance, investigations of anomalous conductivity structures by magnetotelluric (MT) soundings and other (EM) and electrical methods (audio MT soundings, d.c. dipole-dipole and VLF resistivity profilings) with shorter sampling distance, and studies of the near-surface conductivity by airborne EM surveys. The variety of methods provide an ability to map efficiently crustal conductivity structures from a regional scale of hundreds of kilometres down to local details of some metres in the anomalous structures. The Precambrian of the Fennoscandian Shield is characterized by roughly NW-SE-directed elongated belts of conductors which separate more resistive crustal blocks. The latter serve as transparent windows through which to probe deep electrical structure and belts of conductors as tectonic markers of ancient orogenic zones including (1) the Kittilä-Vetrenny Poyas conductor, (2) the Lapland Granulite Belt and Inari-Pechenga-Imandra-Varzuga conductors, (3) the Archaean-Proterozoic boundary conductor and (4) the Southern Finland Conductor. The conductive belts—orogenic conductors—indicate places where crustal masses collided and were finally sealed together. Enhanced conductivity in the orogenic conductors is caused primarily by an electronic conducting mechanism in graphite- and sulphide-bearing metasedimentary rocks. Estimations of the lower-crustal conductivity indicate a laterally heterogeneous lower crust in the Fennoscandian Shield. Archaean lower crust seems to be in general more resistive than the Early Proterozoic lower crust of the Karelian and Svecofennian Domains. The lower crust in the southwestern part of the Svecofennian Domain and in the Sveconorwegian Domain seems to be more resistive than in the central part of the Svecofennian Domain.

Influence of serial electrical stimulations of perifornical and posterior hypothalamic orexin-containing neurons on regulation of sleep homeostasis and sleep-wakefulness cycle recovery from experimental comatose state and anesthesia-induced deep sleep.

PubMed

Chijavadze, E; Chkhartishvili, E; Babilodze, M; Maglakelidze, N; Nachkebia, N

2013-11-01

The work was aimed for the ascertainment of following question - whether Orexin-containing neurons of dorsal and lateral hypothalamic, and brain Orexinergic system in general, are those cellular targets which can speed up recovery of disturbed sleep homeostasis and accelerate restoration of sleep-wakefulness cycle phases during some pathological conditions - experimental comatose state and/or deep anesthesia-induced sleep. Study was carried out on white rats. Modeling of experimental comatose state was made by midbrain cytotoxic lesions at intra-collicular level.Animals were under artificial respiration and special care. Different doses of Sodium Ethaminal were used for deep anesthesia. 30 min after comatose state and/or deep anesthesia induced sleep serial electrical stimulations of posterior and/or perifornical hypothalamus were started. Stimulation period lasted for 1 hour with the 5 min intervals between subsequent stimulations applied by turn to the left and right side hypothalamic parts.EEG registration of cortical and hippocampal electrical activity was started immediately after experimental comatose state and deep anesthesia induced sleep and continued continuously during 72 hour. According to obtained new evidences, serial electrical stimulations of posterior and perifornical hypothalamic Orexin-containing neurons significantly accelerate recovery of sleep homeostasis, disturbed because of comatose state and/or deep anesthesia induced sleep. Speed up recovery of sleep homeostasis was manifested in acceleration of coming out from comatose state and deep anesthesia induced sleep and significant early restoration of sleep-wakefulness cycle behavioral states.

Investigation of Parallel Radiofrequency Transmission for the Reduction of Heating in Long Conductive Leads in 3 Tesla Magnetic Resonance Imaging

PubMed Central

McElcheran, Clare E.; Yang, Benson; Anderson, Kevan J. T.; Golenstani-Rad, Laleh; Graham, Simon J.

2015-01-01

Deep Brain Stimulation (DBS) is increasingly used to treat a variety of brain diseases by sending electrical impulses to deep brain nuclei through long, electrically conductive leads. Magnetic resonance imaging (MRI) of patients pre- and post-implantation is desirable to target and position the implant, to evaluate possible side-effects and to examine DBS patients who have other health conditions. Although MRI is the preferred modality for pre-operative planning, MRI post-implantation is limited due to the risk of high local power deposition, and therefore tissue heating, at the tip of the lead. The localized power deposition arises from currents induced in the leads caused by coupling with the radiofrequency (RF) transmission field during imaging. In the present work, parallel RF transmission (pTx) is used to tailor the RF electric field to suppress coupling effects. Electromagnetic simulations were performed for three pTx coil configurations with 2, 4, and 8-elements, respectively. Optimal input voltages to minimize coupling, while maintaining RF magnetic field homogeneity, were determined for all configurations using a Nelder-Mead optimization algorithm. Resulting electric and magnetic fields were compared to that of a 16-rung birdcage coil. Experimental validation was performed with a custom-built 4-element pTx coil. In simulation, 95-99% reduction of the electric field at the tip of the lead was observed between the various pTx coil configurations and the birdcage coil. Maximal reduction in E-field was obtained with the 8-element pTx coil. Magnetic field homogeneity was comparable to the birdcage coil for the 4- and 8-element pTx configurations. In experiment, a temperature increase of 2±0.15°C was observed at the tip of the wire using the birdcage coil, whereas negligible increase (0.2±0.15°C) was observed with the optimized pTx system. Although further research is required, these initial results suggest that the concept of optimizing pTx to reduce DBS heating effects holds considerable promise. PMID:26237218

Investigation of Parallel Radiofrequency Transmission for the Reduction of Heating in Long Conductive Leads in 3 Tesla Magnetic Resonance Imaging.

PubMed

McElcheran, Clare E; Yang, Benson; Anderson, Kevan J T; Golenstani-Rad, Laleh; Graham, Simon J

2015-01-01

Deep Brain Stimulation (DBS) is increasingly used to treat a variety of brain diseases by sending electrical impulses to deep brain nuclei through long, electrically conductive leads. Magnetic resonance imaging (MRI) of patients pre- and post-implantation is desirable to target and position the implant, to evaluate possible side-effects and to examine DBS patients who have other health conditions. Although MRI is the preferred modality for pre-operative planning, MRI post-implantation is limited due to the risk of high local power deposition, and therefore tissue heating, at the tip of the lead. The localized power deposition arises from currents induced in the leads caused by coupling with the radiofrequency (RF) transmission field during imaging. In the present work, parallel RF transmission (pTx) is used to tailor the RF electric field to suppress coupling effects. Electromagnetic simulations were performed for three pTx coil configurations with 2, 4, and 8-elements, respectively. Optimal input voltages to minimize coupling, while maintaining RF magnetic field homogeneity, were determined for all configurations using a Nelder-Mead optimization algorithm. Resulting electric and magnetic fields were compared to that of a 16-rung birdcage coil. Experimental validation was performed with a custom-built 4-element pTx coil. In simulation, 95-99% reduction of the electric field at the tip of the lead was observed between the various pTx coil configurations and the birdcage coil. Maximal reduction in E-field was obtained with the 8-element pTx coil. Magnetic field homogeneity was comparable to the birdcage coil for the 4- and 8-element pTx configurations. In experiment, a temperature increase of 2±0.15°C was observed at the tip of the wire using the birdcage coil, whereas negligible increase (0.2±0.15°C) was observed with the optimized pTx system. Although further research is required, these initial results suggest that the concept of optimizing pTx to reduce DBS heating effects holds considerable promise.

Simple electrical model and initial experiments for intra-body communications.

PubMed

Gao, Y M; Pun, S H; Du, M; Mak, P U; Vai, M I

2009-01-01

Intra-Body Communication(IBC) is a short range "wireless" communication technique appeared in recent years. This technique relies on the conductive property of human tissue to transmit the electric signal among human body. This is beneficial for devices networking and sensors among human body, and especially suitable for wearable sensors, telemedicine system and home health care system as in general the data rates of physiologic parameters are low. In this article, galvanic coupling type IBC application on human limb was investigated in both its mathematical model and related experiments. The experimental results showed that the proposed mathematical model was capable in describing the galvanic coupling type IBC under low frequency. Additionally, the calculated result and experimental result also indicated that the electric signal induced by the transmitters of IBC can penetrate deep into human muscle and thus, provide an evident that IBC is capable of acting as networking technique for implantable devices.

Power Without Wires (POWOW)

NASA Technical Reports Server (NTRS)

Brandhorst, Henry W., Jr.; Howell, Joe (Technical Monitor)

2002-01-01

Electric propulsion has emerged as a cost-effective solution to a wide range of satellite applications. Deep Space 1 successfully demonstrated electric propulsion as the primary propulsion source for a satellite. The POWOW concept is a solar-electric propelled spacecraft capable of significant cargo and short trip times for traveling to Mars. There it would enter areosynchronous orbit (Mars GEO equivalent) and beam power to surface installations via lasers. The concept has been developed with industrial partner expertise in high efficiency solar cells, advanced concentrator modules, innovative arrays, and high power electric propulsion systems. The present baseline spacecraft design providing 898 kW using technologies expected to be available in 2003 will be described. Areal power densities approaching 350 W/sq m at 80 C operating temperatures and wing level specific powers of over 350 W/kg are projected. Details of trip times and payloads to Mars are presented. Electric propulsion options include Hall, MPD, and ion thrusters of various power levels and trade studies have been conducted to define the most advantageous options. Because the design is modular, learning curve methodology has been applied to determine expected cost reductions and is included.

Outer Planet Exploration with Advanced Radioisotope Electric Propulsion

NASA Technical Reports Server (NTRS)

Oleson, Steven; Gefert, Leon; Patterson, Michael; Schreiber, Jeffrey; Benson, Scott; McAdams, Jim; Ostdiek, Paul

2002-01-01

In response to a request by the NASA Deep Space Exploration Technology Program, NASA Glenn Research Center conducted a study to identify advanced technology options to perform a Pluto/Kuiper mission without depending on a 2004 Jupiter Gravity Assist, but still arriving before 2020. A concept using a direct trajectory with small, sub-kilowatt ion thrusters and Stirling radioisotope power systems was shown to allow the same or smaller launch vehicle class as the chemical 2004 baseline and allow a launch slip and still flyby in the 2014 to 2020 timeframe. With this promising result the study was expanded to use a radioisotope power source for small electrically propelled orbiter spacecraft for outer planet targets such as Uranus, Neptune, and Pluto.

Electric signalling in fruit trees in response to water applications and light-darkness conditions.

PubMed

Gurovich, Luis A; Hermosilla, Paulo

2009-02-15

A fundamental property of all living organisms is the generation and conduction of electrochemical impulses throughout their different tissues and organs, resulting from abiotic and biotic changes in environmental conditions. In plants and animals, signal transmission can occur over long and short distances, and it can correspond to intra- and inter-cellular communication mechanisms that determine the physiological behaviour of the organism. Rapid plant and animal responses to environmental changes are associated with electrical excitability and signalling. The same molecules and pathways are used to drive physiological responses, which are characterized by movement (physical displacement) in animals and by continuous growth in plants. In the field of environmental plant electrophysiology, automatic and continuous measurements of electrical potential differences (DeltaEP) between plant tissues can be effectively used to study information transport mechanisms and physiological responses that result from external stimuli on plants. A critical mass of data on electrical behaviour in higher plants has accumulated in the last 5 years, establishing plant neurobiology as the most recent discipline of plant science. In this work, electrical potential differences were monitored continuously using Ag/AgCl microelectrodes, which were inserted 15mm deep into sapwood at various positions in the trunks of several fruit-bearing trees. Electrodes were referenced to an unpolarisable Ag/AgCl microelectrode, which was installed 5cm deep in the soil. Systematic patterns of DeltaEP during day-night cycles and at different conditions of soil water availability are discussed as alternative tools to assess early plant stress conditions. This research relates to the adaptive response of trees to soil water availability and light-darkness cycles.

Regional two-dimensional magnetotelluric profile in West Bohemia/Vogtland reveals deep conductive channel into the earthquake swarm region

NASA Astrophysics Data System (ADS)

Muñoz, Gerard; Weckmann, Ute; Pek, Josef; Kováčiková, Světlana; Klanica, Radek

2018-03-01

The West Bohemia/Vogtland region, characterized by the intersection of the Eger (Ohře) Rift and the Mariánské Lázně fault, is a geodynamically active area exhibiting repeated occurrence of earthquake swarms, massive CO2 emanations and mid Pleistocene volcanism. The Eger Rift is the only known intra-continental region in Europe where such deep seated, active lithospheric processes currently take place. We present an image of electrical resistivity obtained from two-dimensional inversion of magnetotelluric (MT) data acquired along a regional profile crossing the Eger Rift. At the near surface, the Cheb basin and the aquifer feeding the mofette fields of Bublák and Hartoušov have been imaged as part of a region of very low resistivity. The most striking resistivity feature, however, is a deep reaching conductive channel which extends from the surface into the lower crust spatially correlated with the hypocentres of the seismic events of the Nový Kostel Focal Zone. This channel has been interpreted as imaging a pathway from a possible mid-crustal fluid reservoir to the surface. The resistivity model reinforces the relation between the fluid circulation along deep-reaching faults and the generation of the earthquakes. Additionally, a further conductive channel has been revealed to the south of the profile. This other feature could be associated to fossil hydrothermal alteration related to Mýtina and/or Neualbenreuth Maar structures or alternatively could be the signature of a structure associated to the suture between the Saxo-Thuringian and Teplá-Barrandian zones, whose surface expression is located only a few kilometres away.

Validation of a Portable Low-Power Deep Brain Stimulation Device Through Anxiolytic Effects in a Laboratory Rat Model.

PubMed

Kouzani, Abbas Z; Kale, Rajas P; Zarate-Garza, Pablo Patricio; Berk, Michael; Walder, Ken; Tye, Susannah J

2017-09-01

Deep brain stimulation (DBS) devices deliver electrical pulses to neural tissue through an electrode. To study the mechanisms and therapeutic benefits of deep brain stimulation, murine preclinical research is necessary. However, conducting naturalistic long-term, uninterrupted animal behavioral experiments can be difficult with bench-top systems. The reduction of size, weight, power consumption, and cost of DBS devices can assist the progress of this research in animal studies. A low power, low weight, miniature DBS device is presented in this paper. This device consists of electronic hardware and software components including a low-power microcontroller, an adjustable current source, an n-channel metal-oxide-semiconductor field-effect transistor, a coin-cell battery, electrode wires and a software program to operate the device. Evaluation of the performance of the device in terms of battery lifetime and device functionality through bench and in vivo tests was conducted. The bench test revealed that this device can deliver continuous stimulation current pulses of strength [Formula: see text], width [Formula: see text], and frequency 130 Hz for over 22 days. The in vivo tests demonstrated that chronic stimulation of the nucleus accumbens (NAc) with this device significantly increased psychomotor activity, together with a dramatic reduction in anxiety-like behavior in the elevated zero-maze test.

Experimental and theoretical characterization of the voltage distribution generated by deep brain stimulation.

PubMed

Miocinovic, Svjetlana; Lempka, Scott F; Russo, Gary S; Maks, Christopher B; Butson, Christopher R; Sakaie, Ken E; Vitek, Jerrold L; McIntyre, Cameron C

2009-03-01

Deep brain stimulation (DBS) is an established therapy for the treatment of Parkinson's disease and shows great promise for numerous other disorders. While the fundamental purpose of DBS is to modulate neural activity with electric fields, little is known about the actual voltage distribution generated in the brain by DBS electrodes and as a result it is difficult to accurately predict which brain areas are directly affected by the stimulation. The goal of this study was to characterize the spatial and temporal characteristics of the voltage distribution generated by DBS electrodes. We experimentally recorded voltages around active DBS electrodes in either a saline bath or implanted in the brain of a non-human primate. Recordings were made during voltage-controlled and current-controlled stimulation. The experimental findings were compared to volume conductor electric field models of DBS parameterized to match the different experiments. Three factors directly affected the experimental and theoretical voltage measurements: 1) DBS electrode impedance, primarily dictated by a voltage drop at the electrode-electrolyte interface and the conductivity of the tissue medium, 2) capacitive modulation of the stimulus waveform, and 3) inhomogeneity and anisotropy of the tissue medium. While the voltage distribution does not directly predict the neural response to DBS, the results of this study do provide foundational building blocks for understanding the electrical parameters of DBS and characterizing its effects on the nervous system.

Deep dielectric charging of the lunar regolith within permanently shadowed regions

NASA Astrophysics Data System (ADS)

Jordan, A.; Stubbs, T. J.; Joyce, C. J.; Schwadron, N.; Smith, S. S.; Spence, H.; Wilson, J. K.

2013-12-01

Galactic cosmic rays (GCRs) and solar energetic particles (SEPs) can penetrate within the lunar regolith, causing deep dielectric charging. The discharging timescale depends on the regolith's electrical conductivity and permittivity. In permanently shadowed regions (PSRs) near the lunar poles, this timescale is on the order of a lunation (~20 days). To estimate the resulting electric fields within the regolith, we develop a data-driven, one-dimensional, time-dependent model. For model inputs, we use GCR data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on board the Lunar Reconnaissance Orbiter (LRO) and SEP data from the Electron, Proton, and Alpha Monitor (EPAM) on the Advanced Composition Explorer (ACE). We find that, during the recent solar minimum, GCRs create persistent electric fields up to 700 V/m. We also find that large SEP events create sporadic but strong fields (>10^6 V/m) that may induce dielectric breakdown. Meteoritic gardening limits the amount of time the regolith can spend close enough to the surface to be charged by SEPs, and we find that the gardened regolith within PSRs has likely experienced >10^6 breakdown-inducing events. Since dielectric breakdown typically creates cracks along the boundaries of changes in dielectric constant, we predict repeated breakdown to have fragmented a fraction of the regolith within PSRs into its mineralogical components.

Impact of cysts during radiofrequency lesioning in deep brain structures—a simulation and in vitro study

NASA Astrophysics Data System (ADS)

Johansson, Johannes D.; Loyd, Dan; Wårdell, Karin; Wren, Joakim

2007-06-01

Radiofrequency lesioning of nuclei in the thalamus or the basal ganglia can be used to reduce symptoms caused by e.g. movement disorders such as Parkinson's disease. Enlarged cavities containing cerebrospinal fluid (CSF) are commonly present in the basal ganglia and tend to increase in size and number with age. Since the cavities have different electrical and thermal properties compared with brain tissue, it is likely that they can affect the lesioning process and thereby the treatment outcome. Computer simulations using the finite element method and in vitro experiments have been used to investigate the impact of cysts on lesions' size and shape. Simulations of the electric current and temperature distributions as well as convective movements have been conducted for various sizes, shapes and locations of the cysts as well as different target temperatures. Circulation of the CSF caused by the heating was found to spread heat effectively and the higher electric conductivity of the CSF increased heating of the cyst. These two effects were together able to greatly alter the resulting lesion size and shape when the cyst was in contact with the electrode tip. Similar results were obtained for the experiments.

"Diffusion" region of magnetic reconnection: electron orbits and the phase space mixing

NASA Astrophysics Data System (ADS)

Kropotkin, Alexey P.

2018-05-01

The nonlinear dynamics of electrons in the vicinity of magnetic field neutral lines during magnetic reconnection, deep inside the diffusion region where the electron motion is nonadiabatic, has been numerically analyzed. Test particle orbits are examined in that vicinity, for a prescribed planar two-dimensional magnetic field configuration and with a prescribed uniform electric field in the neutral line direction. On electron orbits, a strong particle acceleration occurs due to the reconnection electric field. Local instability of orbits in the neighborhood of the neutral line is pointed out. It combines with finiteness of orbits due to particle trapping by the magnetic field, and this should lead to the effect of mixing in the phase space, and the appearance of dynamical chaos. The latter may presumably be viewed as a mechanism producing finite conductivity in collisionless plasma near the neutral line. That conductivity is necessary to provide violation of the magnetic field frozen-in condition, i.e., for magnetic reconnection to occur in that region.

Leakage current transport mechanism under reverse bias in Au/Ni/GaN Schottky barrier diode

NASA Astrophysics Data System (ADS)

Peta, Koteswara Rao; Kim, Moon Deock

2018-01-01

The leakage current transport mechanism under reverse bias of Au/Ni/GaN Schottky diode is studied using temperature dependent current-voltage (I-V-T) and capacitance-voltage (C-V) characteristics. I-V measurement in this study is in the range of 140 K-420 K in steps of 10 K. A reduction in voltage dependent barrier height and a strong internal electric field in depletion region under reverse bias suggested electric field enhanced thermionic emission in carrier transport via defect states in Au/Ni/GaN SBD. A detailed analysis of reverse leakage current revealed two different predominant transport mechanisms namely variable-range hopping (VRH) and Poole-Frenkel (PF) emission conduction at low (<260 K) and high (>260 K) temperatures respectively. The estimated thermal activation energies (0.20-0.39 eV) from Arrhenius plot indicates a trap assisted tunneling of thermally activated electrons from a deep trap state into a continuum of states associated with each conductive threading dislocation.

Electrical resistivity structure at the North-Central Turkey inferred from three-dimensional magnetotellurics

NASA Astrophysics Data System (ADS)

Özaydın, Sinan; Tank, Sabri Bülent; Karaş, Mustafa

2018-03-01

Magnetotelluric data analyses and three-dimensional modeling techniques were implemented to investigate the crustal electrical structure in the North-Central Turkey, along a 190-km-long profile crossing Çankırı Basin, İzmir-Ankara-Erzincan Suture Zone and Central Pontides. In this area, the segment of the North Anatolian Fault (NAF) shows 280-km-long restraining bend, where it was near the focus of the hazardous 1943 Tosya Earthquake (M: 7.6). Structure around the NAF exhibits resistive characteristics at both sides of the fault reaching to at least 25 km of depth. Fluids below the brittle-ductile transition were not detected which will nucleate earthquakes in the area. This resistive structure implies an asperity zone of the NAF, which was ruptured in 1943. The presence of a fluid-bearing upwelling conductive anomaly in Central Pontides may suggest that beneath the deep brittle crust, there may exists a fluid-enriched conductive forearc region, which may have caused by a prograde source related to paleo-tectonic processes.

The application of moment methods to the analysis of fluid electrical conductivity logs in boreholes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loew, S.; Tsang, Chin-Fu; Hale, F.V.

1990-08-01

This report is one of a series documenting the results of the Nagra-DOE Cooperative (NDC-I) research program in which the cooperating scientists explore the geological, geophysical, hydrological, geochemical, and structural effects anticipated from the use of a rock mass as a geologic repository for nuclear waste. Previous reports have presented a procedure for analyzing a time sequence of wellbore electric conductivity logs in order to obtain outflow parameters of fractures intercepted by the borehole, and a code, called BORE, used to simulate borehole fluid conductivity profiles given these parameters. The present report describes three new direct (not iterative) methods formore » analyzing a short time series of electric conductivity logs based on moment quantities of the individual outflow peaks and applies them to synthetic as well as to field data. The results of the methods discussed show promising results and are discussed in terms of their respective advantages and limitations. In particular it is shown that one of these methods, the so-called Partial Moment Method,'' is capable of reproducing packer test results from field experiments in the Leuggern deep well within a factor of three, which is below the range of what is recognized as the precision of packer tests themselves. Furthermore the new method is much quicker than the previously used iterative fitting procedure and is even capable of handling transient fracture outflow conditions. 20 refs., 11 figs., 10 tabs.« less

Low Cost Electric Propulsion Thruster for Deep Space Robotic Science Missions

NASA Technical Reports Server (NTRS)

Manzella, David

2008-01-01

Electric Propulsion (EP) has found widespread acceptance by commercial satellite providers for on-orbit station keeping due to the total life cycle cost advantages these systems offer. NASA has also sought to benefit from the use of EP for primary propulsion onboard the Deep Space-1 and DAWN spacecraft. These applications utilized EP systems based on gridded ion thrusters, which offer performance unequaled by other electric propulsion thrusters. Through the In-Space Propulsion Project, a lower cost thruster technology is currently under development designed to make electric propulsion intended for primary propulsion applications cost competitive with chemical propulsion systems. The basis for this new technology is a very reliable electric propulsion thruster called the Hall thruster. Hall thrusters, which have been flown by the Russians dating back to the 1970s, have been used by the Europeans on the SMART-1 lunar orbiter and currently employed by 15 other geostationary spacecraft. Since the inception of the Hall thruster, over 100 of these devices have been used with no known failures. This paper describes the latest accomplishments of a development task that seeks to improve Hall thruster technology by increasing its specific impulse, throttle-ability, and lifetime to make this type of electric propulsion thruster applicable to NASA deep space science missions. In addition to discussing recent progress on this task, this paper describes the performance and cost benefits projected to result from the use of advanced Hall thrusters for deep space science missions.

Nuclear Electric Propulsion for Deep Space Exploration

NASA Astrophysics Data System (ADS)

Schmidt, G.

Nuclear electric propulsion (NEP) holds considerable promise for deep space exploration in the future. Research and development of this technology is a key element of NASA's Nuclear Systems Initiative (NSI), which is a top priority in the President's FY03 NASA budget. The goal is to develop the subsystem technologies that will enable application of NEP for missions to the outer planets and beyond by the beginning of next decade. The high-performance offered by nuclear-powered electric thrusters will benefit future missions by (1) reducing or eliminating the launch window constraints associated with complex planetary swingbys, (2) providing the capability to perform large spacecraft velocity changes in deep space, (3) increasing the fraction of vehicle mass allocated to payload and other spacecraft systems, and, (3) in some cases, reducing trip times over other propulsion alternatives. Furthermore, the nuclear energy source will provide a power-rich environment that can support more sophisticated science experiments and higher- speed broadband data transmission than current deep space missions. This paper addresses NASA's plans for NEP, and discusses the subsystem technologies (i.e., nuclear reactors, power conversion and electric thrusters) and system concepts being considered for the first generation of NEP vehicles.

Compensation and persistent photocapacitance in homoepitaxial Sn-doped β-Ga2O3

NASA Astrophysics Data System (ADS)

Polyakov, A. Y.; Smirnov, N. B.; Shchemerov, I. V.; Gogova, D.; Tarelkin, S. A.; Pearton, S. J.

2018-03-01

The electrical properties of epitaxial β-Ga2O3 doped with Sn (1016-9 × 1018 cm-3) and grown by metalorganic chemical vapor deposition on semi-insulating β-Ga2O3 substrates are reported. Shallow donors attributable to Sn were observed only in a narrow region near the film/substrate interface and with a much lower concentration than the total Sn density. For heavily Sn doped films (Sn concentration, 9 × 1018 cm-3), the electrical properties in the top portion of the layer were determined by deep centers with a level at Ec-0.21 eV not described previously. In more lightly doped layers, the Ec-0.21 eV centers and deeper traps at Ec-0.8 eV were present, with the latter pinning the Fermi level. Low temperature photocapacitance and capacitance voltage measurements of illuminated samples indicated the presence of high densities (1017-1018 cm-3) of deep acceptors with an optical ionization threshold of 2.3 eV. Optical deep level transient spectroscopy (ODLTS) and photoinduced current transient spectroscopy (PICTS) detected electron traps at Ec-0.8 eV and Ec-1.1 eV. For lightly doped layers, the compensation of film conductivity was mostly provided by the Ec-2.3 eV acceptors. For heavily Sn doped films, deep acceptor centers possibly related to Ga vacancies were significant. The photocapacitance and the photocurrent caused by illumination at low temperatures were persistent, with an optical threshold of 1.9 eV and vanished only at temperatures of ˜400 K. The capture barrier for electrons causing the persistent photocapacitance effect was estimated from ODLTS and PICTS to be 0.25-0.35 eV.

Electromagnetic deep-probing (100-1000 KMS) of the Earth's interior from artificial satellites: Constraints on the regional emplacement of crustal resources

NASA Technical Reports Server (NTRS)

Hermance, J. F. (Principal Investigator)

1981-01-01

An algorithm was developed to address the problem of electromagnetic coupling of ionospheric current systems to both a homogeneous Earth having finite conductivity, and to an Earth having gross lateral variations in its conductivity structure, e.g., the ocean-land interface. Typical results from the model simulation for ionospheric currents flowing parallel to a representative geologic discontinuity are shown. Although the total magnetic field component at the satellite altitude is an order of magnitude smaller than at the Earth's surface (because of cancellation effects from the source current), the anomalous behavior of the satellite observations as the vehicle passes over the geologic contact is relatively more important pronounced. The results discriminate among gross lithospheric structures because of difference in electrical conductivity.

Understanding the effect of pulsed electric fields on thermostability of connective tissue isolated from beef pectoralis muscle using a model system.

PubMed

Alahakoon, A U; Oey, I; Silcock, P; Bremer, P

2017-10-01

Brisket is a low value/tough meat cut that contains a large amount of connective tissue. Conversion of collagen into gelatin during heating reduces the toughness of the connective tissue however this conversion is slow at low cooking temperatures (around 60°C). The objective of this project was to determine the ability of pulsed electric field (PEF) processing to reduce the thermal stability of connective tissue. To achieve this, a novel model system was designed in which connective tissue obtained from beef deep pectotalis muscle (brisket) was exposed to PEF at combinations of electric field strength (1.0 and 1.5kV/cm) and specific energy (50 and 100kJ/kg) within an agar matrix at electrical conductivities representing the electrical conductivity found in brisket. Differential scanning calorimetry showed that PEF treatment significantly (p<0.05) decreased the denaturation temperature of connective tissue compared to untreated samples. Increasing electric field strength and the specific energy increased the Ringer soluble collagen fraction. PEF treated samples showed higher solubilization compared to the untreated samples at both 60°C and 70°C in heat solubility test. SEM examination of PEF treated (at 1.5kV/cm and 100kJ/kg) and untreated samples revealed that PEF appeared to increase the porosity of the connective tissue structure. These finding suggest that PEF processing is a technology that could be used to improve the tenderness and decrease the cooking time of collagen rich, meat cuts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Site Selection for Hvdc Ground Electrodes

NASA Astrophysics Data System (ADS)

Freire, P. F.; Pereira, S. Y.

2014-12-01

High-Voltage Direct Current (HVDC) transmission systems are composed of a bipole transmission line with a converter substation at each end. Each substation may be equipped with a HVDC ground electrode, which is a wide area (up to 1 km Ø) and deep (from 3 to 100m) electrical grounding. When in normal operation, the ground electrode will dissipate in the soil the unbalance of the bipole (~1.5% of the rated current). When in monopolar operation with ground return, the HVDC electrode will inject in the soil the nominal pole continuous current, of about 2000 to 3000 Amperes, continuously for a period up to a few hours. HVDC ground electrodes site selection is a work based on extensive geophysical and geological surveys, in order to attend the desired design requirements established for the electrodes, considering both its operational conditions (maximum soil temperature, working life, local soil voltage gradients etc.) and the interference effects on the installations located up to 50 km away. This poster presents the geophysical investigations conducted primarily for the electrodes site selection, and subsequently for the development of the crust resistivity model, which will be used for the interference studies. A preliminary site selection is conducted, based on general geographical and geological criteria. Subsequently, the geology of each chosen area is surveyed in detail, by means of electromagnetic/electrical geophysical techniques, such as magnetotelluric (deep), TDEM (near-surface) and electroresistivity (shallow). Other complementary geologic and geotechnical surveys are conducted, such as wells drilling (for geotechnical characterization, measurement of the water table depth and water flow, and electromagnetic profiling), and soil and water sampling (for measurement of thermal parameters and evaluation of electrosmosis risk). The site evaluation is a dynamic process along the surveys, and some sites will be discarded. For the two or three final sites, the inversion of the combined deep, near-surface and shallow apparent resistivity curves, results in the layered crust resistivity models. These models will allow for the preliminary interference studies, that will result on the selection of the final electrode site (one for each converter substation).

Successful application of frequency-domain airborne electromagnetic system with a grounded electric source

NASA Astrophysics Data System (ADS)

Kang, L.; Lin, J.; Liu, C.; Zhou, H.; Ren, T.; Yao, Y.

2017-12-01

A new frequency-domain AEM system with a grounded electric source, which was called ground-airborne frequency-domain electromagnetic (GAFEM) system, was proposed to extend penetration depth without compromising the resolution and detection efficiency. In GAFEM system, an electric source was placed on the ground to enlarge the strength of response signals. UVA was chosen as aircraft to reduce interaction noise and improve its ability to adapt to complex terrain. Multi-source and multi-frequency emission method has been researched and applied to improve the efficiency of GAFEM system. 2n pseudorandom sequence was introduced as transmitting waveform, to ensure resolution and detection efficiency. Inversion-procedure based on full-space apparent resistivity formula was built to realize GAFEM method and extend the survey area to non-far field. Based on GAFEM system, two application was conducted in Changchun, China, to map the deep conductive structure. As shown in the results of this exploration, GAFEM system shows its effectiveness to conductive structure, obtaining a depth of about 1km with a source-receiver distance of over 6km. And it shows the same level of resolution with CSAMT method with an over 10 times of efficiency. This extended a range of important applications where the terrain is too complex to be accessed or large penetration depth is required in a large survey area.

Can multi-scale calibrations allow MT-derived resistivities to be used to probe the structure of the deep crust?

NASA Astrophysics Data System (ADS)

Toy, Virginia; Billia, Marco; Easingwood, Richard; Kirilova, Martina; Kluge, Emma; Sauer, Katrina; Sutherland, Rupert; Timms, Nicholas; Townend, John

2017-04-01

Our current knowledge of microstructural and mechanical controls on rock resistivity is such that identical magnetotelluric (MT) anomalies could result from a highly mineralized but extinct shear zone, or from an unmineralized, fluid saturated, active shear zone. In pursuit of the ability to interpret the structure and activity (rather than just the presence) of buried geological structures from electromagnetic data, we are investigating correlations between rock structure and electrical properties of ductile shear zone rocks recovered from the active Alpine Fault Zone, New Zealand. Multi-scale measurements of resistivity exist for this zone: its ductile portions have anomalously high electrical conductivity identified in MT models constructed as part of the South Island Geophysical Transect (SIGHT). Additionally wireline resistivities were measured in situ to 820 m depth during the recent Deep Fault Drilling Project (DFDP-2), and resisistivity of hand samples has been measured at laboratory conditions [Kluge et al., Abstract EGU2017-10139]. In exhumed and borehole samples, the distributions and arrangements of conductivity carriers - graphite, amorphous carbon, and grain boundary pores that would have contained brines or other conductive fluids at depth, have been characterised. These vary systematically according to the total ductile shear strain they have accommodated [Kirilova et al., Abstract EGU2017-5773; Sauer et al., Abstract EGU2017-10485]. Transmission electron microscopy analyses of grain boundaries also indicate that they contain carbon. The next phases of our investigation involve: (i) construction of crustal fluid composition models by quantitative microstructural and compositional/mineralogical mapping of fluid remnants and their solid residues and calibration of these using in situ measurements of fluid composition in DFDP-2 at depths to 820 m; (ii) calculation of resistivities for real microstructures based on electrical properties of the individual component minerals and fluids - for microstructures fully characterised in three-dimensions; (iii) measurement of the effects of dynamic linking of phases during ductile creep of solid rock on complex resistivity of DFDP samples at a range of realistic crustal temperatures and pressures. A particular challenge in this study is to determine appropriate scaling relationships of electrical properties among samples, boreholes, and MT models because dielectric constants of minerals depend on frequency of the imposed current, which varies with scale and, consequently, measurement method. We invite discussion of strategies to overcome this.

The influence of thermal annealing on the characteristics of Au/Ni Schottky contacts on n-type 4 H-SiC

NASA Astrophysics Data System (ADS)

Omotoso, E.; Auret, F. D.; Igumbor, E.; Tunhuma, S. M.; Danga, H. T.; Ngoepe, P. N. M.; Taleatu, B. A.; Meyer, W. E.

2018-05-01

The effects of isochronal annealing on the electrical, morphological and structural characteristics of Au/Ni/4 H-SiC Schottky barrier diodes (SBDs) have been studied. Current-voltage ( I- V), capacitance-voltage ( C- V), deep-level transient spectroscopy, scanning electron microscope (SEM) and X-ray diffraction measurements were employed to study the thermal effect on the characteristics of the SBDs. Prior to thermal annealing of Schottky contacts, the I- V measurements results confirmed the good rectification behaviour with ideality factor of 1.06, Schottky barrier height of 1.20 eV and series resistance of 7 Ω. The rectification properties after annealing was maintained up to an annealing temperature of 500 °C, but deviated slightly above 500 °C. The uncompensated ionized donor concentration decreased with annealing temperature, which could be attributed to out-diffusion of the 4 H-SiC into the Au/Ni contacts and decrease in bonding due to formation of nickel silicides. We observed the presence of four deep-level defects with energies 0.09, 0.11, 0.16 and 0.65 eV below the conduction band before and after the isochronal annealing up to 600 °C. The conclusion drawn was that annealing did not affect the number of deep-level defects present in Au/Ni/4 H-SiC contacts. The variations in electrical properties of the devices were attributed to the phase transformations and interfacial reactions that occurred after isochronal annealing.

Electrical anisotropy in the presence of oceans—a sensitivity study

NASA Astrophysics Data System (ADS)

Cembrowski, Marcel; Junge, Andreas

2018-05-01

Electrical anisotropy in the presence of oceans is particularly relevant at continent-ocean subduction zones (e.g. Cascadian and Andean Margin), where seismic anisotropy has been found with trench-parallel or perpendicular fast direction. The identification of electrical anisotropy at such locations sheds new light on the relation between seismic and electrical anisotropies. At areas confined by two opposite oceans, for example the Pyrenean Area and Central America, we demonstrate that the superposed responses of both oceans generate a uniform and large phase split of the main phase tensor axes. The pattern of the tipper arrows is comparatively complicated and it is often difficult to associate their length and orientation to the coast effect. On the basis of simple forward models involving opposite oceans and anisotropic layers, we show that both structures generate similar responses. In the case of a deep anisotropic layer, the resistivity and phase split generated by the oceans alone will be increased or decreased depending on the azimuth of the conducting horizontal principal axes. The 3-D isotropic inversion of the anisotropic forward responses reproduces the input data reasonably well. The anisotropy is explained by large opposed conductors outside the station grid and by tube-like elongated conductors representing a macroscopic anisotropy. If the conductive direction is perpendicular to the shorelines, the anisotropy is not recovered by 3-D isotropic inversion.

Electrical geophysical study over the Norman Landfill, near Norman, Oklahoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bisdorf, R.J.

In 1995 and 1996 the US Geological Survey made 40 Schlumberger dc electrical resistivity soundings at the Norman Landfill, near Norman, Oklahoma. Interpretation of the resistivity data indicates that high resistivities (>300 ohm-m) are related to dry sand, intermediate resistivities (45-300 ohm-m) are related to freshwater saturated sand, and low resistivities (<45 ohm-m) are related to fine-grained materials or materials saturated with the conductive fluids. Interpreted resistivity maps show a low resistivity anomaly that extends from under the landfill to just past a nearby slough. This anomaly corresponds to known areas of ground water contamination. A resistivity cross section, constructedmore » from interpreted Schlumberger soundings, shows that this low resistivity anomaly is about 5 m deep and up to 9 m thick.« less

Assessment of deep tissue hyperalgesia in the groin - a method comparison of electrical vs. pressure stimulation.

PubMed

Aasvang, E K; Werner, M U; Kehlet, H

2014-09-01

Deep pain complaints are more frequent than cutaneous in post-surgical patients, and a prevalent finding in quantitative sensory testing studies. However, the preferred assessment method - pressure algometry - is indirect and tissue unspecific, hindering advances in treatment and preventive strategies. Thus, there is a need for development of methods with direct stimulation of suspected hyperalgesic tissues to identify the peripheral origin of nociceptive input. We compared the reliability of an ultrasound-guided needle stimulation protocol of electrical detection and pain thresholds to pressure algometry, by performing identical test-retest sequences 10 days apart, in deep tissues in the groin region. Electrical stimulation was performed by five up-and-down staircase series of single impulses of 0.04 ms duration, starting from 0 mA in increments of 0.2 mA until a threshold was reached and descending until sensation was lost. Method reliability was assessed by Bland-Altman plots, descriptive statistics, coefficients of variance and intraclass correlation coefficients. The electrical stimulation method was comparable to pressure algometry regarding 10 days test-retest repeatability, but with superior same-day reliability for electrical stimulation (P < 0.05). Between-subject variance rather than within-subject variance was the main source for test variation. There were no systematic differences in electrical thresholds across tissues and locations (P > 0.05). The presented tissue-specific direct deep tissue electrical stimulation technique has equal or superior reliability compared with the indirect tissue-unspecific stimulation by pressure algometry. This method may facilitate advances in mechanism based preventive and treatment strategies in acute and chronic post-surgical pain states. © 2014 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Varying Indian crustal front in the southern Tibetan Plateau as revealed by magnetotelluric data

NASA Astrophysics Data System (ADS)

Xie, Chengliang; Jin, Sheng; Wei, Wenbo; Ye, Gaofeng; Zhang, Letian; Dong, Hao; Yin, Yaotian

2017-10-01

In the southern Tibetan plateau, which is considered to be the ongoing India-Eurasia continental collision zone, tracing of the Indian crustal front beneath Tibet is still controversial. We conducted deep subsurface electrical modeling in southern Tibet and discuss the geometry of the front of the Indian crust. Three areas along the Yarlung-Zangbo river zone for which previous magnetotelluric (MT) data are available were inverted independently using a three-dimensional MT inversion algorithm ModEM. Electrical horizontal slices at different depths and north-south oriented cross sections at different longitudes were obtained to provide a geoelectrical perspective for deep processes beneath the Tethyan Himalaya and Lhasa terrane. Horizontal slices at depths greater than - 15 km show that the upper crust is covered with resistive layers. Below a depth of - 20 km, discontinuous conductive distributions are primarily concentrated north of the Yarlung-Zangbo sutures (YZS) and could be imaged from mid- to lower crust. The results show that the maximum depth to which the resistive layers extend is over - 20 km, while the mid- to lower crustal conductive zones extend to depths greater than - 50 km. The results indicate that the conductive region in the mid- to lower crust can be imaged primarily from the YZS to south of the Bangong-Nujiang sutures in western Tibet and to 31°N in eastern Tibet. The northern front of the conductive zones appears as an irregular barrier to the Indian crust from west to east. We suggest that a relatively less conductive subsurface in the northern portion of the barrier indicates a relatively cold and strong crust and that the front of the Indian crust might be halted in the south of the barrier. We suggest that the Indian crustal front varies from west to east and has at least reached: 33.5°N at 80°E, 31°N at 85°E, and 30.5°N at 87°E and 92°E.[Figure not available: see fulltext.

Magnetism and the interior of the moon

NASA Technical Reports Server (NTRS)

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

1974-01-01

The application of lunar magnetic field measurements to the study of properties of the lunar crust and deep interior is reviewed. Following a brief description of lunar magnetometers and the lunar magnetic environment, measurements of lunar remanent fields and their interaction with the solar plasma are discussed. The magnetization induction mode is considered with reference to lunar magnetic permeability and iron abundance calculations. Finally, electrical conductivity and temperature calculations from analyses of poloidal induction, for data taken in both the solar wind and in the geomagnetic tail, are reviewed.

Reconfiguration of NASA GRC's Vacuum Facility 6 for Testing of Advanced Electric Propulsion System (AEPS) Hardware

NASA Technical Reports Server (NTRS)

Peterson, Peter; Kamhawi, Hani; Huang, Wensheng; Yim, John; Haag, Tom; Mackey, Jonathan; McVetta, Mike; Sorrelle, Luke; Tomsik, Tom; Gilligan, Ryan;

Reconfiguration of NASA GRC's Vacuum Facility 6 for Testing of Advanced Electric Propulsion System (AEPS) Hardware

NASA Technical Reports Server (NTRS)

Peterson, Peter Y.; Kamhawi, Hani; Huang, Wensheng; Yim, John; Haag, Tom; Mackey, Jonathan; McVetta, Mike; Sorrelle, Luke; Tomsik, Tom; Gilligan, Ryan;

Reconfiguration of NASA GRC's Vacuum Facility 6 for Testing of Advanced Electric Propulsion System (AEPS) Hardware

NASA Technical Reports Server (NTRS)

Peterson, Peter Y.; Kamhawi, Hani; Huang, Wensheng; Yim, John T.; Haag, Thomas W.; Mackey, Jonathan A.; McVetta, Michael S.; Sorrelle, Luke T.; Tomsik, Thomas M.; Gilligan, Ryan P.;

Effects of electrode settings on chlorine generation efficiency of electrolyzing seawater.

PubMed

Hsu, Guoo-Shyng Wang; Hsia, Chih-Wei; Hsu, Shun-Yao

2015-12-01

Electrolyzed water has significant disinfection effects, can comply with food safety regulations, and is environmental friendly. We investigated the effects of immersion depth of electrodes, stirring, electrode size, and electrode gap on the properties and chlorine generation efficiency of electrolyzing seawater and its storage stability. Results indicated that temperature and oxidation-reduction potential (ORP) of the seawater increased gradually, whereas electrical conductivity decreased steadily in electrolysis. During the electrolysis process, pH values and electric currents also decreased slightly within small ranges. Additional stirring or immersing the electrodes deep under the seawater significantly increased current density without affecting its electric efficiency and current efficiency. Decreasing electrode size or increasing electrode gap decreased chlorine production and electric current of the process without affecting its electric efficiency and current efficiency. Less than 35% of chlorine in the electrolyzed seawater was lost in a 3-week storage period. The decrement trend leveled off after the 1 st week of storage. The electrolyzing system is a convenient and economical method for producing high-chlorine seawater, which will have high potential applications in agriculture, aquaculture, or food processing. Copyright © 2015. Published by Elsevier B.V.

Comparison of formation and fluid-column logs in a heterogeneous basalt aquifer

USGS Publications Warehouse

Paillet, F.L.; Williams, J.H.; Oki, D.S.; Knutson, K.D.

2002-01-01

Deep observation boreholes in the vicinity of active production wells in Honolulu, Hawaii, exhibit the anomalous condition that fluid-column electrical conductivity logs and apparent profiles of pore-water electrical conductivity derived from induction conductivity logs are nearly identical if a formation factor of 12.5 is assumed. This condition is documented in three boreholes where fluid-column logs clearly indicate the presence of strong borehole flow induced by withdrawal from partially penetrating water-supply wells. This result appears to contradict the basic principles of conductivity-log interpretation. Flow conditions in one of these boreholes was investigated in detail by obtaining flow profiles under two water production conditions using the electromagnetic flowmeter. The flow-log interpretation demonstrates that the fluid-column log resembles the induction log because the amount of inflow to the borehole increases systematically upward through the transition zone between deeper salt water and shallower fresh water. This condition allows the properties of the fluid column to approximate the properties of water entering the borehole as soon as the upflow stream encounters that producing zone. Because this condition occurs in all three boreholes investigated, the similarity of induction and fluid-column logs is probably not a coincidence, and may relate to aquifer response under the influence of pumping from production wells.

Comparison of formation and fluid-column logs in a heterogeneous basalt aquifer.

PubMed

Paillet, F L; Williams, J H; Oki, D S; Knutson, K D

2002-01-01

Deep observation boreholes in the vicinity of active production wells in Honolulu, Hawaii, exhibit the anomalous condition that fluid-column electrical conductivity logs and apparent profiles of pore-water electrical conductivity derived from induction conductivity logs are nearly identical if a formation factor of 12.5 is assumed. This condition is documented in three boreholes where fluid-column logs clearly indicate the presence of strong borehole flow induced by withdrawal from partially penetrating water-supply wells. This result appears to contradict the basic principles of conductivity-log interpretation. Flow conditions in one of these boreholes was investigated in detail by obtaining flow profiles under two water production conditions using the electromagnetic flowmeter. The flow-log interpretation demonstrates that the fluid-column log resembles the induction log because the amount of inflow to the borehole increases systematically upward through the transition zone between deeper salt water and shallower fresh water. This condition allows the properties of the fluid column to approximate the properties of water entering the borehole as soon as the upflow stream encounters that producing zone. Because this condition occurs in all three boreholes investigated, the similarity of induction and fluid-column logs is probably not a coincidence, and may relate to aquifer response under the influence of pumping from production wells.

Deep crustal electromagnetic structure of central India tectonic zone and its implications

NASA Astrophysics Data System (ADS)

Naganjaneyulu, K.; Naidu, G. Dhanunjaya; Rao, M. Someswara; Shankar, K. Ravi; Kishore, S. R. K.; Murthy, D. N.; Veeraswamy, K.; Harinarayana, T.

2010-07-01

Magnetotelluric data at 45 locations along the Mahan-Khajuria Kalan profile in the central India tectonic zone are analysed. This 290 km long profile yields data in the period range 0.001-1000 s across the tectonic elements of the study region bounded by Purna fault, Gavligarh fault, Tapti fault, Narmada South fault and Narmada North fault. Multi-site, multi-frequency analysis suggests N70°E as the geo-electric strike direction. Data rotated into the N70°E strike direction are modelled using a non-linear conjugate gradient scheme with error floors of 10% for both apparent resistivity and phase components. Two-dimensional magnetotelluric model yields conductors that correlate with known faults in the study region and regional seismicity. Presence of a -30 mgal gravity high together with the observed conductive bodies (less than 20 ohm m) in the deep crust beneath the Purna graben and Tapti valley is explained by the process of magmatic underplating. The conductive bodies beneath the Mahakoshal rift belt and Vindhyans accompanied by regional gravity lows of the order -70 mgal are attributed to the presence of deep crustal fluids. Following the re-activation model proposed for the entire region, the conductors (20 ohm m) at various depth levels correspond to mafic magmatic and/or fluid intrusions controlled by deep-seated faults that seem to tap reservoirs beyond the crust-mantle boundary. The shallow depth localized faults also seem to have facilitated further upward movement of these underplated material and fluids release during this process.

Intra-operative recording of motor tract potentials at the cervico-medullary junction following scalp electrical and magnetic stimulation of the motor cortex.

PubMed Central

Thompson, P D; Day, B L; Crockard, H A; Calder, I; Murray, N M; Rothwell, J C; Marsden, C D

1991-01-01

Activity in descending motor pathways after scalp electrical and magnetic brain stimulation of the motor cortex was recorded from the exposed cervico-medullary junction in six patients having trans-oral surgery of the upper cervical spine. Recordings during deep anaesthesia without muscle paralysis revealed an initial negative potential (D wave) at about 2 ms with electrical stimulation in five of the six patients. This was followed by a muscle potential which obscured any later waveforms. Magnetic stimulation produced clear potentials in only one patient. The earliest wave to magnetic stimulation during deep anaesthesia was 1-2 ms later than the earliest potential to electrical stimulation. Following lightening of the anaesthetic and the administration of muscle relaxants a series of later negative potentials (I waves) were more clearly seen to both electrical and magnetic stimulation. More I waves were recorded to magnetic stimulation during light anaesthesia than during deep anaesthesia. Increasing the intensity of electrical stimulation also produced an extra late I wave. At the highest intensity of magnetic stimulation the latency of the earliest potential was comparable to the D wave to electrical stimulation. The intervals between these various D and I waves corresponded to those previously described for the timing of single motor unit discharge after cortical stimulation. PMID:1654395

Electrical stimulation site influences the spatial distribution of motor units recruited in tibialis anterior.

PubMed

Okuma, Yoshino; Bergquist, Austin J; Hong, Mandy; Chan, K Ming; Collins, David F

2013-11-01

To compare the spatial distribution of motor units recruited in tibialis anterior (TA) when electrical stimulation is applied over the TA muscle belly versus the common peroneal nerve trunk. Electromyography (EMG) was recorded from the surface and from fine wires in superficial and deep regions of TA. Separate M-wave recruitment curves were constructed for muscle belly and nerve trunk stimulation. During muscle belly stimulation, significantly more current was required to generate M-waves that were 5% of the maximal M-wave (M max; M5%max), 50% M max (M 50%max) and 95% M max (M 95%max) at the deep versus the superficial recording site. In contrast, during nerve trunk stimulation, there were no differences in the current required to reach M5%max, M 50%max or M 95%max between deep and superficial recording sites. Surface EMG reflected activity in both superficial and deep muscle regions. Stimulation over the muscle belly recruited motor units from superficial to deep with increasing stimulation amplitude. Stimulation over the nerve trunk recruited superficial and deep motor units equally, regardless of stimulation amplitude. These results support the idea that where electrical stimulation is applied markedly affects how contractions are produced and have implications for the interpretation of surface EMG data. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

A New Theory of Mix in Omega Capsule Implosions

NASA Astrophysics Data System (ADS)

Knoll, Dana; Chacon, Luis; Rauenzahn, Rick; Simakov, Andrei; Taitano, William; Welser-Sherrill, Leslie

2014-10-01

We put forth a new mix model that relies on the development of a charge-separation electrostatic double-layer at the fuel-pusher interface early in the implosion of an Omega plastic ablator capsule. The model predicts a sizable pusher mix (several atom %) into the fuel. The expected magnitude of the double-layer field is consistent with recent radial electric field measurements in Omega plastic ablator implosions. Our theory relies on two distinct physics mechanisms. First, and prior to shock breakout, the formation of a double layer at the fuel-pusher interface due to fast preheat-driven ionization. The double-layer electric field structure accelerates pusher ions fairly deep into the fuel. Second, after the double-layer mix has occurred, the inward-directed fuel velocity and temperature gradients behind the converging shock transports these pusher ions inward. We first discuss the foundations of this new mix theory. Next, we discuss our interpretation of the radial electric field measurements on Omega implosions. Then we discuss the second mechanism that is responsible for transporting the pusher material, already mixed via the double-layer deep into the fuel, on the shock convergence time scale. Finally we make a connection to recent mix motivated experimental data on. This work conducted under the auspices of the National Nuclear Security Administration of the U.S. Department of Energy at Los Alamos National Laboratory, managed by LANS, LLC under Contract DE-AC52-06NA25396.

Effects of Electrical and Optogenetic Deep Brain Stimulation on Synchronized Oscillatory Activity in Parkinsonian Basal Ganglia.

PubMed

Ratnadurai-Giridharan, Shivakeshavan; Cheung, Chung C; Rubchinsky, Leonid L

2017-11-01

Conventional deep brain stimulation of basal ganglia uses high-frequency regular electrical pulses to treat Parkinsonian motor symptoms but has a series of limitations. Relatively new and not yet clinically tested, optogenetic stimulation is an effective experimental stimulation technique to affect pathological network dynamics. We compared the effects of electrical and optogenetic stimulation of the basal gangliaon the pathologicalParkinsonian rhythmic neural activity. We studied the network response to electrical stimulation and excitatory and inhibitory optogenetic stimulations. Different stimulations exhibit different interactions with pathological activity in the network. We studied these interactions for different network and stimulation parameter values. Optogenetic stimulation was found to be more efficient than electrical stimulation in suppressing pathological rhythmicity. Our findings indicate that optogenetic control of neural synchrony may be more efficacious than electrical control because of the different ways of how stimulations interact with network dynamics.

Cycle life test and failure model of nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Smithrick, J. J.

1983-01-01

Six ampere hour individual pressure vessel nickel hydrogen cells were charge/discharge cycled to failure. Failure as used here is defined to occur when the end of discharge voltage degraded to 0.9 volts. They were cycled under a low earth orbit cycle regime to a deep depth of discharge (80 percent of rated ampere hour capacity). Both cell designs were fabricated by the same manufacturer and represent current state of the art. A failure model was advanced which suggests both cell designs have inadequate volume tolerance characteristics. The limited existing data base at a deep depth of discharge (DOD) was expanded. Two cells of each design were cycled. One COMSAT cell failed at cycle 1712 and the other failed at cycle 1875. For the Air Force/Hughes cells, one cell failed at cycle 2250 and the other failed at cycle 2638. All cells, of both designs, failed due to low end of discharge voltage (0.9 volts). No cell failed due to electrical shorts. After cell failure, three different reconditioning tests (deep discharge, physical reorientation, and open circuit voltage stand) were conducted on all cells of each design. A fourth reconditioning test (electrolyte addition) was conducted on one cell of each design. In addition post cycle cell teardown and failure analysis were performed on the one cell of each design which did not have electrolyte added after failure.

Influence of annealing atmosphere on formation of electrically-active defects in rutile TiO2

NASA Astrophysics Data System (ADS)

Zimmermann, C.; Bonkerud, J.; Herklotz, F.; Sky, T. N.; Hupfer, A.; Monakhov, E.; Svensson, B. G.; Vines, L.

2018-04-01

Electronic states in the upper part of the bandgap of reduced and/or hydrogenated n-type rutile TiO2 single crystals have been studied by means of thermal admittance and deep-level transient spectroscopy measurements. The studies were performed at sample temperatures between 28 and 300 K. The results reveal limited charge carrier freeze-out even at 28 K and evidence the existence of dominant shallow donors with ionization energies below 25 meV. Interstitial atomic hydrogen is considered to be a major contributor to these shallow donors, substantiated by infrared absorption measurements. Three defect energy levels with positions of about 70 meV, 95 meV, and 120 meV below the conduction band edge occur in all the studied samples, irrespective of the sample production batch and the post-growth heat treatment used. The origin of these levels is discussed in terms of electron polarons, intrinsic point defects, and/or common residual impurities, where especially interstitial titanium atoms, oxygen vacancies, and complexes involving Al atoms appear as likely candidates. In contrast, no common deep-level defect, exhibiting a charge state transition in the 200-700 meV range below the conduction band edge, is found in different samples. This may possibly indicate a strong influence on deep-level defects by the post-growth heat treatments employed.

The deep space 1 extended mission

NASA Astrophysics Data System (ADS)

Rayman, Marc D.; Varghese, Philip

2001-03-01

The primary mission of Deep Space 1 (DS1), the first flight of the New Millennium program, completed successfully in September 1999, having exceeded its objectives of testing new, high-risk technologies important for future space and Earth science missions. DS1 is now in its extended mission, with plans to take advantage of the advanced technologies, including solar electric propulsion, to conduct an encounter with comet 19P/Borrelly in September 2001. During the extended mission, the spacecraft's commercial star tracker failed; this critical loss prevented the spacecraft from achieving three-axis attitude control or knowledge. A two-phase approach to recovering the mission was undertaken. The first involved devising a new method of pointing the high-gain antenna to Earth using the radio signal received at the Deep Space Network as an indicator of spacecraft attitude. The second was the development of new flight software that allowed the spacecraft to return to three-axis operation without substantial ground assistance. The principal new feature of this software is the use of the science camera as an attitude sensor. The differences between the science camera and the star tracker have important implications not only for the design of the new software but also for the methods of operating the spacecraft and conducting the mission. The ambitious rescue was fully successful, and the extended mission is back on track.

Probing the electrical switching of a memristive optical antenna by STEM EELS

PubMed Central

Schoen, David T.; Holsteen, Aaron L.; Brongersma, Mark L.

2016-01-01

The scaling of active photonic devices to deep-submicron length scales has been hampered by the fundamental diffraction limit and the absence of materials with sufficiently strong electro-optic effects. Plasmonics is providing new opportunities to circumvent this challenge. Here we provide evidence for a solid-state electro-optical switching mechanism that can operate in the visible spectral range with an active volume of less than (5 nm)3 or ∼10−6 λ3, comparable to the size of the smallest electronic components. The switching mechanism relies on electrochemically displacing metal atoms inside the nanometre-scale gap to electrically connect two crossed metallic wires forming a cross-point junction. These junctions afford extreme light concentration and display singular optical behaviour upon formation of a conductive channel. The active tuning of plasmonic antennas attached to such junctions is analysed using a combination of electrical and optical measurements as well as electron energy loss spectroscopy in a scanning transmission electron microscope. PMID:27412052

Enhancement of p-type conductivity by modifying the internal electric field in Mg- and Si-δ-codoped AlxGa1-xN/AlyGa1-yN superlattices

NASA Astrophysics Data System (ADS)

Li, Jinchai; Yang, Weihuang; Li, Shuping; Chen, Hangyang; Liu, Dayi; Kang, Junyong

2009-10-01

The internal electric field is modified by using Mg- and Si-δ-codoped AlxGa1-xN/AlyGa1-yN superlattices (SLs). The first-principles simulation results show that the internal electric field in SL has been significantly intensified due to the charge transferring from Si-doped interface to Mg-doped interface. Accordingly, the Mg- and Si-δ-codoped p-type Al0.2Ga0.8N/GaN SLs are grown by metalorganic vapor phase epitaxy and higher hole concentration as much as twice of that in modulation-doped SL has been achieved, as determined by Hall effect measurements. Furthermore, by applying Mg- and Si-δ-codoped AlxGa1-xN/AlyGa1-yN SLs with high Al content as the p-type layers, we have fabricated deep ultraviolet light emitting diodes with superior current-voltage characteristics by lowering Mg-acceptor activation energy.

Electrical stimulation of acupoint combinations against deep venous thrombosis in elderly bedridden patients after major surgery.

PubMed

Hou, Lili; Chen, Cuiping; Xu, Lei; Yin, Peihao; Peng, Wen

2013-04-01

To compare the effects of electrical stimulation of different acupoint combinations among postoperative bedridden elderly patients on hemorheology and deep venous blood flow velocity and investigate the.role of electrical stimulation against deep vein thrombosis (DVT). From November 2010 to October 2011, a total of 160 elderly bedridden patients after major surgery were divided into the conventional care group, invigorating and promoting Qi group, blood-activating and damp-eliminating group, and acupoint-combination stimulation group. Whole blood viscosity, plasma viscosity, D-dimer levels, lower limb skin temperature, lower limb circumference, and flow velocities of the external iliac vein, femoral vein, popliteal vein, and deep calf veins in all patients were documented and compared among the four groups. Whole blood viscosity, plasma viscosity, D-dimer levels, and lower limb circumference were significantly reduced in the blood-activating and damp-eliminating group compared with the conventional care group (P < 0.05) and were almost equal to those in the acupoint-combination stimulation group (P > 0.05). Lower limb venous flow velocities were accelerated in the invigorating and promoting Qi group compared with the other groups, excluding the acupoint-combination stimulation group (P < 0.05). Hemorheological indices in postoperative bedridden elderly patients were improved after combined electrical stimulation at Yinlingquan (SP 9) and Sanyinjiao (SP 6). Combined electrical stimulation at Zusanli (ST 36) and Taichong (LR 3), on the other hand, accelerated lower limb venous flow.

Parvalbumin interneuron mediated feedforward inhibition controls signal output in the deep layers of the perirhinal‐entorhinal cortex

PubMed Central

Willems, Janske G. P.; Wadman, Wytse J.

2018-01-01

Abstract The perirhinal (PER) and lateral entorhinal (LEC) cortex form an anatomical link between the neocortex and the hippocampus. However, neocortical activity is transmitted through the PER and LEC to the hippocampus with a low probability, suggesting the involvement of the inhibitory network. This study explored the role of interneuron mediated inhibition, activated by electrical stimulation in the agranular insular cortex (AiP), in the deep layers of the PER and LEC. Activated synaptic input by AiP stimulation rarely evoked action potentials in the PER‐LEC deep layer excitatory principal neurons, most probably because the evoked synaptic response consisted of a small excitatory and large inhibitory conductance. Furthermore, parvalbumin positive (PV) interneurons—a subset of interneurons projecting onto the axo‐somatic region of principal neurons—received synaptic input earlier than principal neurons, suggesting recruitment of feedforward inhibition. This synaptic input in PV interneurons evoked varying trains of action potentials, explaining the fast rising, long lasting synaptic inhibition received by deep layer principal neurons. Altogether, the excitatory input from the AiP onto deep layer principal neurons is overruled by strong feedforward inhibition. PV interneurons, with their fast, extensive stimulus‐evoked firing, are able to deliver this fast evoked inhibition in principal neurons. This indicates an essential role for PV interneurons in the gating mechanism of the PER‐LEC network. PMID:29341361

3-D electrical structure across the Yadong-Gulu rift revealed by magnetotelluric data: New insights on the extension of the upper crust and the geometry of the underthrusting Indian lithospheric slab in southern Tibet

NASA Astrophysics Data System (ADS)

Wang, Gang; Wei, Wenbo; Ye, Gaofeng; Jin, Sheng; Jing, Jianen; Zhang, Letian; Dong, Hao; Xie, Chengliang; Omisore, Busayo O.; Guo, Zeqiu

2017-09-01

The approximately north-south trending Cenozoic Yadong-Gulu rift (YGR) in the eastern Lhasa block is an ideal location to investigate the extensional kinematic mechanism of the upper crust and the deformation characteristics of the Indian lithospheric slab in southern Tibet. The magnetotelluric (MT) method has been widely used in probing subsurface structures at lithospheric scale and is sensitive to high electrically conductive body (conductor). A three-dimensional (3-D) inversion of MT data was conducted to derive the east-west electrical structures across the northern segment of the YGR. The result reveals that the conductors in the middle crust are not continuous in the east-west direction. The deep conductor underneath the YGR is interpreted to result from the tearing of the Indian lithospheric slab. The upper crust to the east of the YGR is significantly intruded by underlying conductors. Based on the features of the 3-D inversion result from this study and other geophysical observations, the formation of the YGR is most likely caused by tearing of the Indian lithospheric slab through the pull of mid-lower crustal conductors that have locally weak strength beneath the YGR.

Lithospheric electrical structure of the middle Lhasa terrane in the south Tibetan plateau

NASA Astrophysics Data System (ADS)

Liang, Hongda; Jin, Sheng; Wei, Wenbo; Gao, Rui; Ye, Gaofeng; Zhang, Letian; Yin, Yaotian; Lu, Zhanwu

2018-04-01

The Lhasa terrane in southern Tibetan plateau is a huge tectono-magmatic belt and an important metallogenic belt. Its formation evolution process and mineralization are affected by the subduction of oceanic plate and subsequent continental collision. However, the evolution of Lhasa terrane has been a subject of much debate for a long time. The Lithospheric structure records the deep processes of the subduction of oceanic plate and continental collision. The magnetotelluric (MT) method can probe the sub-surface electrical conductivity, newly dense broadband and long period magnetotelluric data were collected along a south-north trending profile that across the Lhasa terrane at 88°-89°E. Dimensionality analyses demonstrated that the MT data can be interpreted using two-dimensional approaches, and the regional strike direction was determined as N110°E.Based on data analysis results, a two-dimensional (2-D) resistivity model of crust and upper mantle was derived from inversion of the transverse electric mode, transverse magnetic mode and vertical magnetic field data. Inversion model shows a large north-dipping resistor that extended from the upper crust to upper mantle beneath the Himalaya and the south of Lhasa Terrane, which may represent the subducting Indian continental lithosphere. The 31°N may be an important boundary in the Lhasa Terrane, the south performs a prominent high-conductivity anomaly from the lower crust to upper mantle which indicates the existence of asthenosphere upwelling, while the north performs a higher resistivity and may have a reworking ancient basement. The formation of the ore deposits in the study area may be related to the upwelling of the mantle material triggered by slab tearing and/or breaking off of the Indian lithosphere, and the mantle material input also contributed the total thickness of the present-day Tibetan crust. The results provide helpful constrains to understand the mechanism of the continent-continent collision and the regional exploratory prospect of the deep resources.

Development of precise measurement systems for deep-sea electrical and magnetic explorations by ROV and AUV

NASA Astrophysics Data System (ADS)

Sayanagi, K.; Goto, T.; Harada, M.; Kasaya, T.; Sawa, T.; Nakajima, T.; Isezaki, N.; Takeuchi, A.; Nagao, T.; Matsuo, J.

2009-12-01

It is generally not easy to obtain the fine-scale structure of the oceanic crust with accuracy better than several tens of meters, because the deep sea prevents us from approaching the bottom in most parts of the oceans. The necessity of such detailed information, however, has increased in researches and developments of the ocean floor. For instance, it is essential in development of ocean floor resources like sea-floor hydrothermal deposits and methane hydrate in order to estimate accurate abundance of those resources. Therefore, it is very important to develop some instruments for precise measurements of the oceanic crust. From this standpoint, we have developed new measurement systems for electrical and magnetic explorations by Remotely Operated Vehicle (ROV) and Autonomous Underwater Vehicle (AUV). In our project, the main target is sea-floor hydrothermal deposits. We are working on research and development regarding measurement of the magnetic field with high resolution and high sampling rate, electrical exploration with accurately controlled source signals, electrical exploration tools for shallow and deep targets, versatile instruments of electrical and magnetic explorations with multi-platforms (deep-tow system, ROV, and AUV), comprehensive analyses of electrical, magnetic, acoustic and thermal data, and so on. We finished basic designs of the magnetic and electrical observation systems last year, and we have been manufacturing each instrument. So far, the first test of the magnetic exploration system was carried out in the Kumano Basin during the R/V Yokosuka cruise in July, 2009. In the test, a vector magnetometer on AUV “Urashima” and a scalar magnetometer hung below towing vehicle “Yokosuka Deep-Tow” successfully detected magnetic anomaly produced by an artificial magnetic body set up on the ocean floor. Details will be reported in another paper by Harada, M. et al. in this meeting. In addition, various performance tests will be planned for check and improvement of the observation systems. For instance, the vector magnetometer will be tested over a volcanic island using a helicopter. The electrical exploration system will be also tested using ROV “Kaiko 7000II” off the northeastern part of Japan during the R/V Kairei cruise. We will present the outline and the current state of the project in this presentation. Note that this project has been supported by the Ministry of Education, Culture, Sports, Science & Technology (MEXT).

A suppression of differential rotation in Jupiter’s deep interior

NASA Astrophysics Data System (ADS)

Guillot, T.; Miguel, Y.; Militzer, B.; Hubbard, W. B.; Kaspi, Y.; Galanti, E.; Cao, H.; Helled, R.; Wahl, S. M.; Iess, L.; Folkner, W. M.; Stevenson, D. J.; Lunine, J. I.; Reese, D. R.; Biekman, A.; Parisi, M.; Durante, D.; Connerney, J. E. P.; Levin, S. M.; Bolton, S. J.

2018-03-01

Jupiter’s atmosphere is rotating differentially, with zones and belts rotating at speeds that differ by up to 100 metres per second. Whether this is also true of the gas giant’s interior has been unknown, limiting our ability to probe the structure and composition of the planet. The discovery by the Juno spacecraft that Jupiter’s gravity field is north–south asymmetric and the determination of its non-zero odd gravitational harmonics J3, J5, J7 and J9 demonstrates that the observed zonal cloud flow must persist to a depth of about 3,000 kilometres from the cloud tops. Here we report an analysis of Jupiter’s even gravitational harmonics J4, J6, J8 and J10 as observed by Juno and compared to the predictions of interior models. We find that the deep interior of the planet rotates nearly as a rigid body, with differential rotation decreasing by at least an order of magnitude compared to the atmosphere. Moreover, we find that the atmospheric zonal flow extends to more than 2,000 kilometres and to less than 3,500 kilometres, making it fully consistent with the constraints obtained independently from the odd gravitational harmonics. This depth corresponds to the point at which the electric conductivity becomes large and magnetic drag should suppress differential rotation. Given that electric conductivity is dependent on planetary mass, we expect the outer, differentially rotating region to be at least three times deeper in Saturn and to be shallower in massive giant planets and brown dwarfs.

Retaining the 3D framework of zinc sponge anodes upon deep discharge in Zn-air cells.

PubMed

Parker, Joseph F; Nelson, Eric S; Wattendorf, Matthew D; Chervin, Christopher N; Long, Jeffrey W; Rolison, Debra R

2014-11-26

We fabricate three-dimensional zinc electrodes from emulsion-cast sponges of Zn powder that are thermally treated to produce rugged monoliths. This highly conductive, 3D-wired aperiodic scaffold achieves 740 mA h gZn(-1) when discharged in primary Zn-air cells (>90% of theoretical Zn capacity). We use scanning electron microscopy and X-ray diffraction to monitor the microstructural evolution of a series of Zn sponges when oxidized in Zn-air cells to specific depths-of-discharge (20, 40, 60, 80% DOD) at a technologically relevant rate (C/40; 4-6 mA cm(-2)). The Zn sponges maintain their 3D-monolithic form factor at all DOD. The cell resistance remains low under all test conditions, indicating that an inner core of metallic Zn persists that 3D-electrically wires the electrode, even to deep DOD.

Laser processing of ceramics for microelectronics manufacturing

NASA Astrophysics Data System (ADS)

Sposili, Robert S.; Bovatsek, James; Patel, Rajesh

2017-03-01

Ceramic materials are used extensively in the microelectronics, semiconductor, and LED lighting industries because of their electrically insulating and thermally conductive properties, as well as for their high-temperature-service capabilities. However, their brittleness presents significant challenges for conventional machining processes. In this paper we report on a series of experiments that demonstrate and characterize the efficacy of pulsed nanosecond UV and green lasers in machining ceramics commonly used in microelectronics manufacturing, such as aluminum oxide (alumina) and aluminum nitride. With a series of laser pocket milling experiments, fundamental volume ablation rate and ablation efficiency data were generated. In addition, techniques for various industrial machining processes, such as shallow scribing and deep scribing, were developed and demonstrated. We demonstrate that lasers with higher average powers offer higher processing rates with the one exception of deep scribes in aluminum nitride, where a lower average power but higher pulse energy source outperformed a higher average power laser.

Wireless sensors for measuring sub-surface processes in firn

NASA Astrophysics Data System (ADS)

Bagshaw, Elizabeth; Karlsson, Nanna; Lishman, Ben; Bun Lok, Lai; Burrow, Stephen; Wadham, Jemma; Clare, Lindsay; Nicholls, Keith; Corr, Hugh; Brennan, Paul; Eisen, Olaf; Dahl-Jensson, Dorthe

2017-04-01

Subsurface processes exert controls on meltwater storage and densification within firn, which are, by their nature, challenging to measure. We present the results of proof-of-concept tests of wireless ETracer sensors with the East Greenland Ice Core Project (EGRIP) at the Northeast Greenland Ice Stream. ETracers equipped with temperature, pressure and electrical conductivity sensors were deployed in firn boreholes at the centre and the shear margins of the ice stream. Data were returned from a 60m deep test borehole, and continuously for 4 weeks from two 14m deep boreholes, to autonomous receivers at the surface. Two receivers were tested: a station using software radio and PC, and the BAS/UCL ApRES radar system. The sensors were used to track high resolution changes in temperature with depth, changes in densification rates in response to accumulation events and snow redistribution, and the presence of liquid water within the firn.

Subsurface imaging of water electrical conductivity, hydraulic permeability and lithology at contaminated sites by induced polarization

NASA Astrophysics Data System (ADS)

Maurya, P. K.; Balbarini, N.; Møller, I.; Rønde, V.; Christiansen, A. V.; Bjerg, P. L.; Auken, E.; Fiandaca, G.

2018-05-01

At contaminated sites, knowledge about geology and hydraulic properties of the subsurface and extent of the contamination is needed for assessing the risk and for designing potential site remediation. In this study, we have developed a new approach for characterizing contaminated sites through time-domain spectral induced polarization. The new approach is based on: (1) spectral inversion of the induced polarization data through a reparametrization of the Cole-Cole model, which disentangles the electrolytic bulk conductivity from the surface conductivity for delineating the contamination plume; (2) estimation of hydraulic permeability directly from the inverted parameters using a laboratory-derived empirical equation without any calibration; (3) the use of the geophysical imaging results for supporting the geological modelling and planning of drilling campaigns. The new approach was tested on a data set from the Grindsted stream (Denmark), where contaminated groundwater from a factory site discharges to the stream. Two overlapping areas were covered with seven parallel 2-D profiles each, one large area of 410 m × 90 m (5 m electrode spacing) and one detailed area of 126 m × 42 m (2 m electrode spacing). The geophysical results were complemented and validated by an extensive set of hydrologic and geologic information, including 94 estimates of hydraulic permeability obtained from slug tests and grain size analyses, 89 measurements of water electrical conductivity in groundwater, and four geological logs. On average the IP-derived and measured permeability values agreed within one order of magnitude, except for those close to boundaries between lithological layers (e.g. between sand and clay), where mismatches occurred due to the lack of vertical resolution in the geophysical imaging. An average formation factor was estimated from the correlation between the imaged bulk conductivity values and the water conductivity values measured in groundwater, in order to convert the imaging results from bulk conductivity to water conductivity. The geophysical models were actively used for supporting the geological modelling and the imaging of hydraulic permeability and water conductivity allowed for a better discrimination of the clay/lignite lithology from the pore water conductivity. Furthermore, high water electrical conductivity values were found in a deep confined aquifer, which is separated by a low-permeability clay layer from a shallow aquifer. No contamination was expected in this part of the confined aquifer, and confirmation wells were drilled in the zone of increased water electrical conductivity derived from the geophysical results. Water samples from the new wells showed elevated concentrations of inorganic compounds responsible for the increased water electrical conductivity in the confined aquifer and high concentrations of xenobiotic organic contaminants such as chlorinated ethenes, sulfonamides and barbiturates.

Phase Transformations and Metallization of Magnesium Oxide at High Pressure and Temperature

NASA Astrophysics Data System (ADS)

McWilliams, R. Stewart; Spaulding, Dylan K.; Eggert, Jon H.; Celliers, Peter M.; Hicks, Damien G.; Smith, Raymond F.; Collins, Gilbert W.; Jeanloz, Raymond

2012-12-01

Magnesium oxide (MgO) is representative of the rocky materials comprising the mantles of terrestrial planets, such that its properties at high temperatures and pressures reflect the nature of planetary interiors. Shock-compression experiments on MgO to pressures of 1.4 terapascals (TPa) reveal a sequence of two phase transformations: from B1 (sodium chloride) to B2 (cesium chloride) crystal structures above 0.36 TPa, and from electrically insulating solid to metallic liquid above 0.60 TPa. The transitions exhibit large latent heats that are likely to affect the structure and evolution of super-Earths. Together with data on other oxide liquids, we conclude that magmas deep inside terrestrial planets can be electrically conductive, enabling magnetic field-producing dynamo action within oxide-rich regions and blurring the distinction between planetary mantles and cores.

Hydrogen self-diffusion in single crystal olivine and electrical conductivity of the Earth’s mantle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Novella, Davide; Jacobsen, Benjamin; Weber, Peter K.

Nominally anhydrous minerals formed deep in the mantle and transported to the Earth’s surface contain tens to hundreds of ppm wt H 2O, providing evidence for the presence of dissolved water in the Earth’s interior. Even at these low concentrations, H 2O greatly affects the physico-chemical properties of mantle materials, governing planetary dynamics and evolution. The diffusion of hydrogen (H) controls the transport of H 2O in the Earth’s upper mantle, but is not fully understood for olivine ((Mg, Fe) 2SiO 4) the most abundant mineral in this region. Here we present new hydrogen self-diffusion coefficients in natural olivine singlemore » crystals that were determined at upper mantle conditions (2 GPa and 750–900 °C). Hydrogen self-diffusion is highly anisotropic, with values at 900 °C of 10 -10.9, 10 -12.8 and 10 -11.9 m 2/s along [100], [010] and [001] directions, respectively. Combined with the Nernst-Einstein relation, these diffusion results constrain the contribution of H to the electrical conductivity of olivine to be σH = 10 2.12S/m·C H2O·exp -187kJ/mol/(RT). Comparisons between the model presented in this study and magnetotelluric measurements suggest that plausible H 2O concentrations in the upper mantle (≤250 ppm wt) can account for high electrical conductivity values (10 -2–10 -1 S/m) observed in the asthenosphere.« less

Hydrogen self-diffusion in single crystal olivine and electrical conductivity of the Earth’s mantle

DOE PAGES

Novella, Davide; Jacobsen, Benjamin; Weber, Peter K.; ...

2017-07-13

Nominally anhydrous minerals formed deep in the mantle and transported to the Earth’s surface contain tens to hundreds of ppm wt H 2O, providing evidence for the presence of dissolved water in the Earth’s interior. Even at these low concentrations, H 2O greatly affects the physico-chemical properties of mantle materials, governing planetary dynamics and evolution. The diffusion of hydrogen (H) controls the transport of H 2O in the Earth’s upper mantle, but is not fully understood for olivine ((Mg, Fe) 2SiO 4) the most abundant mineral in this region. Here we present new hydrogen self-diffusion coefficients in natural olivine singlemore » crystals that were determined at upper mantle conditions (2 GPa and 750–900 °C). Hydrogen self-diffusion is highly anisotropic, with values at 900 °C of 10 -10.9, 10 -12.8 and 10 -11.9 m 2/s along [100], [010] and [001] directions, respectively. Combined with the Nernst-Einstein relation, these diffusion results constrain the contribution of H to the electrical conductivity of olivine to be σH = 10 2.12S/m·C H2O·exp -187kJ/mol/(RT). Comparisons between the model presented in this study and magnetotelluric measurements suggest that plausible H 2O concentrations in the upper mantle (≤250 ppm wt) can account for high electrical conductivity values (10 -2–10 -1 S/m) observed in the asthenosphere.« less

Hydrogen self-diffusion in single crystal olivine and electrical conductivity of the Earth's mantle.

PubMed

Novella, Davide; Jacobsen, Benjamin; Weber, Peter K; Tyburczy, James A; Ryerson, Frederick J; Du Frane, Wyatt L

2017-07-13

Nominally anhydrous minerals formed deep in the mantle and transported to the Earth's surface contain tens to hundreds of ppm wt H 2 O, providing evidence for the presence of dissolved water in the Earth's interior. Even at these low concentrations, H 2 O greatly affects the physico-chemical properties of mantle materials, governing planetary dynamics and evolution. The diffusion of hydrogen (H) controls the transport of H 2 O in the Earth's upper mantle, but is not fully understood for olivine ((Mg, Fe) 2 SiO 4 ) the most abundant mineral in this region. Here we present new hydrogen self-diffusion coefficients in natural olivine single crystals that were determined at upper mantle conditions (2 GPa and 750-900 °C). Hydrogen self-diffusion is highly anisotropic, with values at 900 °C of 10 -10.9 , 10 -12.8 and 10 -11.9 m 2 /s along [100], [010] and [001] directions, respectively. Combined with the Nernst-Einstein relation, these diffusion results constrain the contribution of H to the electrical conductivity of olivine to be σ H  = 10 2.12 S/m·C H2O ·exp -187kJ/mol/(RT) . Comparisons between the model presented in this study and magnetotelluric measurements suggest that plausible H 2 O concentrations in the upper mantle (≤250 ppm wt) can account for high electrical conductivity values (10 -2 -10 -1  S/m) observed in the asthenosphere.

Long-lived thermal control materials for high temperature and deep space applications

NASA Technical Reports Server (NTRS)

Whitt, Robin; O'Donnell, Tim

1988-01-01

Considerable effort has been put into developing thermal-control materials for the Galileo space-craft. This paper presents a summary of these findings to date with emphasis on requirements, testing and results for the post-Challenger Galileo mission. Polyimide film (Kapton), due to its inherent stability in vacuum, UV, and radiation environments, combined with good mechanical properties over a large temperature range, has been the preferred substrate for spacecraft thermal control materials. Composite outer layers, using Kapton substrates, can be fabricated to meet the requirements of severe space environments. Included in the processing of Kapton-based composite outer layers can be the deposition of metal oxide, metallic and/or polymeric thin-film coatings to provide desirable electrical, optical and thermo-optical properties. In addition, reinforcement of Kapton substrates with fabrics and films is done to improve mechanical properties. Also these substrates can be filled with varying amounts of carbon to achieve particular electrical properties. The investigation and material development reported on here has led to improved thermo-gravimetric stability, surface conductivity, RF transparency, radiation and UV stability, flammability and handle-ability of outer layer thermal control materials for deep space and near-sun spacecraft. Designing, testing, and qualifying composite thermal-control film materials to meet the requirements of the Galileo spacecraft is the scope of this paper.

High-resolution cross-borehole thermal tracer testing in granite: preliminary field results

NASA Astrophysics Data System (ADS)

Brixel, Bernard; Klepikova, Maria; Jalali, Mohammadreza; Amann, Florian; Loew, Simon

2017-04-01

Understanding how heat is transported, stored and exchanged across fractured media is becoming increasingly relevant in our society, as manifested from the growing popularity of modern technologies relying on the subsurface to either source or store heat. One good example is the utilization of heat from deep hydrothermal or petrothermal systems to generate electricity for base load power generation, a technology also known as deep geothermal energy (DGE). While very attractive in principle, the number of geothermal fields producing economical levels of electricity to this day is still very limited - largely due to the difficulty of either locating deep reservoirs that are both sufficiently hot and permeable or, in the absence of the latter, creating them. In this context, the Swiss Competence Center for Energy Research - Supply of Electricity (SCCER - SoE) is carrying out an in situ stimulation and circulation (ISC) experiment at the Grimsel Test Site (GTS), an underground rock lab located in the Aar massif, in the Swiss Alps. The circulation experiment planned for the post-stimulation phase represents one of the key components of this experimental research program, and the outcome of this test is expected to ultimately provide key insights in the factors controlling the performance of enhanced geothermal reservoirs. Therefore, to support the design of this experiment, short-term thermal tracer tests (TTT) were conducted with the objective to (i) assess the feasibility of conducting TTTs in a relatively intact granite (where fluid flow is controlled by a limited number of discrete fractures); (ii) determine optimal experimental setups; and to ultimately (iii) monitor thermal breakthroughs at high spatial and temporal resolution, providing insights on heat transport and complementing the characterization of hydrogeological conditions carried out through conventional means (e.g. hydraulic and/or solute tracer tests). Presented herein are the results of a 10-day thermal tracer test conducted by continuously injecting water at 40°C (ambient groundwater temperatures average around 12-13 °C) across a discrete fractured zone, isolated with packers. Monitoring was achieved using a combination of discrete temperature sensors (PT1000) and FO DTS (Silixa XT system) deployed along a network of both packed-off and open boreholes situated approx. 6-20 m apart from the injection zone. Thermal breakthrough was observed in multiple boreholes, as early as 6-7 hours following the injection of hot water. The rate of increase in temperatures was observed to significantly diminish over time, allowing water in the fracture carrying the majority of heat to reach a temperature of 17°C at the closest observation location. Furthermore, temperature declined along the fracture length. These data allowed us identifying the precise location of conductive fractures, thereby improving our understanding of the connectivity structure of our experimental rock volume. In addition, these results provide significant insights on heat transport and the efficiency of heat-exchange between fractures and the surrounding rock mass at Grimsel.

Static Electric Fields and Lightning Over Land and Ocean in Florida Thunderstorms

NASA Technical Reports Server (NTRS)

Wilson, J. G.; Cummins, K. L.; Simpson, A. A.; Hinckley, A.

2017-01-01

Natural cloud-to-ground (CG) lightning and the charge structure of the associated clouds behave differently over land and ocean. Existing literature has raised questions over the years on the behavior of thunderstorms and lightning over oceans, and there are still open scientific questions. We expand on the observational datasets by obtaining identical electric field observations over coastal land, near-shore, and deep ocean regions during both clear air and thunderstorm periods. Oceanic observations were obtained using two 3-meter NOAA buoys that were instrumented with Campbell Scientific electric field mills to measure the static electric fields. These data were compared to selected electric field records from the existing on-shore electric field mill suite of 31 sensors at Kennedy Space Center (KSC). CG lightning occurrence times, locations and peak current values for both on-shore and ocean were provided by the U.S. National Lightning Detection Network. The buoy instruments were first evaluated on-shore at the Florida coast, to calibrate field enhancements and to confirm proper behavior of the system in elevated-field environments. The buoys were then moored 20NM and 120NM off the coast of KSC in February (20NM) and August (120NM) 2014. Statistically larger CG peak currents were reported over the deep ocean for first strokes and for subsequent strokes with new contacts points. Storm-related static fields were significantly larger at both oceanic sites, likely due to decreased screening by nearby space charge. Time-evolution of the static field during storm development and propagation indicated weak or missing lower positive charge regions in most storms that initiated over the deep ocean, supporting one mechanism for the observed high peak currents in negative first strokes over the deep ocean. This project also demonstrated the practicality of off-shore electric field measurements for safety-related decision making at KSC.

Concentrators Enhance Solar Power Systems

NASA Technical Reports Server (NTRS)

2013-01-01

"Right now, solar electric propulsion is being looked at very seriously," says Michael Piszczor, chief of the photovoltaic and power technologies branch at Glen Research Center. The reason, he explains, originates with a unique NASA mission from the late 1990s. In 1998, the Deep Space 1 spacecraft launched from Kennedy Space Center to test a dozen different space technologies, including SCARLET, or the Solar Concentrator Array with Refractive Linear Element Technology. As a solar array that focused sunlight on a smaller solar cell to generate electric power, SCARLET not only powered Deep Space 1 s instruments but also powered its ion engine, which propelled the spacecraft throughout its journey. Deep Space 1 was the first spacecraft powered by a refractive concentrator design like SCARLET, and also utilized multi-junction solar cells, or cells made of multiple layers of different materials. For the duration of its 38-month mission, SCARLET performed flawlessly, even as Deep Space 1 flew by Comet Borrelly and Asteroid Braille. "Everyone remembers the ion engine on Deep Space 1, but they tend to forget that the SCARLET array powered it," says Piszczor. "Not only did both technologies work as designed, but the synergy between the two, solar power and propulsion together, is really the important aspect of this technology demonstration mission. It was the first successful use of solar electric propulsion for primary propulsion." More than a decade later, NASA is keenly interested in using solar electric propulsion (SEP) for future space missions. A key issue is cost, and SEP has the potential to substantially reduce cost compared to conventional chemical propulsion technology. "SEP allows you to use spacecraft that are smaller, lighter, and less costly," says Piszczor. "Even though it might take longer to get somewhere using SEP, if you are willing to trade time for cost and smaller vehicles, it s a good trade." Potentially, SEP could be used on future science missions in orbit around the Earth or Moon, to planets or asteroids, on deep space science missions, and even on exploration missions. In fact, electric propulsion is already being used on Earth-orbiting satellites for positioning.

Effects of electrolysis time and electric potential on chlorine generation of electrolyzed deep ocean water.

PubMed

Hsu, Guoo-Shyng Wang; Lu, Yi-Fa; Hsu, Shun-Yao

2017-10-01

Electrolyzed water is a sustainable disinfectant, which can comply with food safety regulations and is environmentally friendly. A two-factor central composite design was adopted for studying the effects of electrolysis time and electric potential on the chlorine generation efficiency of electrolyzed deep ocean water (DOW). DOW was electrolyzed in a glass electrolyzing cell equipped with platinum-plated titanium anode and cathode. The results showed that chlorine concentration reached maximal level in the batch process. Prolonged electrolysis reduced chlorine concentration in the electrolyte and was detrimental to electrolysis efficiency, especially under high electric potential conditions. Therefore, the optimal choice of electrolysis time depends on the electrolyzable chloride in DOW and cell potential adopted for electrolysis. The higher the electric potential, the faster the chlorine level reaches its maximum, but the lower the electric efficiency will be. Copyright © 2016. Published by Elsevier B.V.

Capacitance spectroscopy on n-type GaNAs/GaAs embedded quantum structure solar cells

NASA Astrophysics Data System (ADS)

Venter, Danielle; Bollmann, Joachim; Elborg, Martin; Botha, J. R.; Venter, André

2018-04-01

In this study, both deep level transient spectroscopy (DLTS) and admittance spectroscopy (AS) have been used to study the properties of electrically active deep level centers present in GaNAs/GaAs quantum wells (QWs) embedded in p-i-n solar cells. The structures were grown by molecular beam epitaxy (MBE). In particular, the electrical properties of samples with Si (n-type) doping of the QWs were investigated. DLTS revealed four deep level centers in the material, whereas only three were detected by AS. NextNano++ simulation software was used to model the sample band-diagrams to provide reasoning for the origin of the signals produced by both techniques.

Progress in batteries and solar cells - Volume 6

NASA Astrophysics Data System (ADS)

Shimotake, Hiroshi; Voss, Ernst

The present conference encompasses topics in lithium cell development, manganese cell design, lead-acid batteries, fuel cells, nickel-cadmium and other rechargeable batteries, and battery chargers and related power systems. Attention is given to molten carbonate fuel cells, prospects for sodium/sulfur propulsion batteries, ultrathin lithium batteries, solid state batteries, a gelled electrolyte lead-acid battery for deep discharge applications, and phosphoric acid fuel cells. Also discussed are computer-based battery monitors, a novel nickel-iron battery for electric vehicle applications, conductive polymer electrode electrochemical cells, and catalyst- and electrode-related research for phosphoric acid fuel cells.

HORIZONTAL HYBRID SOLAR LIGHT PIPE: AN INTEGRATED SYSTEM OF DAYLIGHT AND ELECTRIC LIGHT

EPA Science Inventory

This project will test the feasibility of an advanced energy efficient perimeter lighting system that integrates daylighting, electric lighting, and lighting controls to reduce electricity consumption. The system is designed to provide adequate illuminance levels in deep-floor...

Tentative anatomy of ZnS-type electroluminescence

NASA Astrophysics Data System (ADS)

Bringuier, E.

1994-05-01

The paper reviews the electrical and optical mechanisms at work in sulfide-based thin-film electroluminescence display devices within the framework of general semiconductor physics. The electrical problem is twofold: (i) charge carriers are sourced at high electric field in a nominally insulating material, the carrier density increasing by almost eight orders of magnitude; (ii) the carriers are transported at high field, with an average energy largely exceeding the thermal one. (i) Carrier sourcing is best understood from direct-current-driven ZnS films, and is ascribed to partly filled deep donors transferring electrons to the conduction band by Fowler-Nordheim tunneling. The deep donors also act as carrier sinkers, and evidence for space charge is afforded by small-signal impedance analysis disclosing a markedly inductive behavior. The conduction picture obtained from dc-driven films is then used to clarify the operation of alternating-current electroluminescence structures where the sulfide is sandwiched between two blocking oxide layers. The electrostatics of the ac structure is investigated in detail including space charge and field nonuniformity, and external observables are related to internal quantities. The simple model of interfacial carrier sourcing and sinking is examined. (ii) High-field electronic transport is controlled by the electron-phonon interaction, and the modeling resorts to numerical simulations or the lucky-drift concept. At low electron energies the interaction with phonons is predominantly polar, while at optical energies it proceeds via deformation potential scattering. In spite of the uncertainties in transport models in that range, it is likely that ˜50% of the electrons overtake 2 eV at the usual operating fields in ZnS. Light emission is associated with impurity luminescence centers embedded in the sulfide host. They are excited while current is flowing, and the ensuing relaxation is partly radiative. We describe the two ways in which an impurity may be excited electrically, namely, impact excitation (internal promotion of the center to a state of higher energy) or impact ionization (with an electron released to the host conduction band). The actual excitation mechanism depends on the position of the impurity excited level relative to the host energy bands. A calculation of the excitation yield (number of excited centers per transferred electron) is detailed in the case of impact excitation. Lastly, a phenomenological description of the various relaxation channels is given in terms of formal kinetics, and the relative importance of radiative relaxation is assessed by means of the deexcitation yield (fraction of centers decaying radiatively), which is defined in the case of the impulse response.

Rupture mechanism and seismotectonics of the Ms6.5 Ludian earthquake inferred from three-dimensional magnetotelluric imaging

NASA Astrophysics Data System (ADS)

Cai, Juntao; Chen, Xiaobin; Xu, Xiwei; Tang, Ji; Wang, Lifeng; Guo, Chunling; Han, Bing; Dong, Zeyi

2017-02-01

A three-dimensional (3-D) resistivity model around the 2014 Ms6.5 Ludian earthquake was obtained. The model shows that the aftershocks were mainly distributed in a shallow inverse L-shaped conductive angular region surrounded by resistive structures. The presences of this shallow conductive zone may be the key factor leading to the severe damage and surface rupture of the Ludian earthquake. A northwest trending local resistive belt along the Baogunao-Xiaohe fault interrupts the northeast trending conductive zone at the Zhaotong-Lianfeng fault zone in the middle crust, which may be the seismogenic structure of the main shock. Based on the 3-D electrical model, combining with GPS, thermal structure, and seismic survey results, a geodynamic model is proposed to interpret the seismotectonics, deep seismogenic background, and deformation characterized by a sinistral strike slip with a tensile component of the Ludian earthquake.

Enthalpy restoration in geothermal energy processing system

DOEpatents

Matthews, Hugh B.

1983-01-01

A geothermal deep well energy extraction system is provided of the general type in which solute-bearing hot water is pumped to the earth's surface from a relatively low temperature geothermal source by transferring thermal energy from the hot water to a working fluid for driving a primary turbine-motor and a primary electrical generator at the earth's surface. The superheated expanded exhaust from the primary turbine motor is conducted to a bubble tank where it bubbles through a layer of sub-cooled working fluid that has been condensed. The superheat and latent heat from the expanded exhaust of the turbine transfers thermal energy to the sub-cooled condensate. The desuperheated exhaust is then conducted to the condenser where it is condensed and sub-cooled, whereupon it is conducted back to the bubble tank via a barometric storage tank. The novel condensing process of this invention makes it possible to exploit geothermal sources which might otherwise be non-exploitable.

Analysis of the disturbed electric field effects in the sporadic E-layers at equatorial and low latitude regions

NASA Astrophysics Data System (ADS)

Araujo Resende, Laysa Cristina; Moro, Juliano; Denardini, Clezio Marcos; Carrasco, Alexander J.; Batista, Paulo; Chen, Sony Su; Batista, Inez S.; Andrioli, Vania Fatima

2016-07-01

In the present work we analyze the disturbed electric field effects in the sporadic E-layers at equatorial regions, Jicamarca (11.57°S, 76.52°O, I: -2°) and São Luís (2°S, 44° O, I: -2.3°), and at low latitude regions, Fortaleza (3.9°S, 38.45°O, I: -9°) and Cachoeira Paulista (22.42°S, 45°O, I: -15°). We have conducted a deep analysis to investigate these effects using a theoretical model for the ionospheric E region, called MIRE. This model is able to simulate the Es layers taking into account the E region winds and electric fields. It calculates the densities for the main molecular (NO^{+}, O_{2}^{+}, N_{2}^{+}) and metallic ions (Fe^{+}, Mg^{+}) by solving the continuity and momentum equations for each species. The main purpose of this analysis is to verify the disturbed electric fields role in the occurrence or disruption of Es layers through simulations. The analysis show that the Es layer formation and dynamics can be influenced by the prompt penetration electric fields that occur during magnetic disturbances. Therefore, the simulations present interesting results that helps to improve the understanding of Es layer behavior during the disturbed periods.

Defect-Enabled Electrical Current Leakage in Ultraviolet Light-Emitting Diodes

DOE PAGES

Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; ...

2015-04-13

The AlGaN materials system offers a tunable, ultra-wide bandgap that is exceptionally useful for high-power electronics and deep ultraviolet optoelectronics. Moseley et al. (pp. 723–726) investigate a structural defect known as an open-core threading dislocation or ''nanopipe'' that is particularly detrimental to devices that employ these materials. Furthermore, an AlGaN thin film was synthesized using metal-organic chemical-vapor deposition. Electrical current leakage is detected at a discrete point using a conductive atomic-force microscope (CAFM). However, no physical feature or abnormality at this location was visible by an optical microscope. The AlGaN thin film was then etched in hot phosphoric acid, andmore » the same location that was previously analyzed was revisited with the CAFM. The point that previously exhibited electrical current leakage had been decorated with a 1.1 μm wide hexagonal pit, which identified the site of electrical current leakage as a nanopipe and allows these defects to be easily observed by optical microscopy. Moreover, with this nanopipe identification and quantification strategy, the authors were able to correlate decreasing ultraviolet light-emitting diode optical output power with increasing nanopipe density.« less

Improvement in thermoelectric power factor of mechanically alloyed p-type SiGe by incorporation of TiB{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Sajid, E-mail: sajidahmadiitkgp@gmail.com; Dubey, K.; Bhattacharya, Shovit

2016-05-23

Nearly 60% of the world’s useful energy is wasted as heat and recovering a fraction of this waste heat by converting it as useful electrical power is an important area of research{sup [1]}. Thermoelectric power generators (TEG) are solid state devices which converts heat into electricity. TEG consists of n and p-type thermoelements connected electrically in series and thermally in parallel{sup [2]}. Silicon germanium (SiGe) alloy is one of the conventional high temperature thermoelectric materials and is being used in radio-isotopes based thermoelectric power generators for deep space exploration programs.Temperature (T) dependence of thermoelectric (TE) properties of p-type SiGe andmore » p-type SiGe-x wt.%TiB{sub 2} (x=6,8,10%) nanocomposite materials has been studied with in the temperature range of 300 K to 1100 K. It is observed that there is an improvement in the power factor (α{sup 2}/ρ) of SiGe alloy on addition of TiB{sub 2} upto 8 wt.% that is mainly due to increase in the Seebeck coefficient (α) and electrical conductivity (σ) of the alloy.« less

Electrical characterisation of SiGe heterojunction bipolar transistors and Si pseudo-HBTS

NASA Astrophysics Data System (ADS)

De Barros, O.; Le Tron, B.; Woods, R. C.; Giroult-Matlakowski, G.; Vincent, G.; Brémond, G.

1996-08-01

This paper reports an electrical characterisation of the emitter-base junction of Si pseudo-HBTs and SiGe HBTs fabricated in a CMOS compatible single polysilicon self-aligned process. From the reverse characteristics it appears that the definition of the emitter-base junction by plasma etching induces peripheral defects that increase the base current of the transistors. Deep level transient spectroscopy measurements show a deep level in the case of SiGe base, whose spatial origin is not fully determinate up to now.

Performance of deep geothermal energy systems

NASA Astrophysics Data System (ADS)

Manikonda, Nikhil

Geothermal energy is an important source of clean and renewable energy. This project deals with the study of deep geothermal power plants for the generation of electricity. The design involves the extraction of heat from the Earth and its conversion into electricity. This is performed by allowing fluid deep into the Earth where it gets heated due to the surrounding rock. The fluid gets vaporized and returns to the surface in a heat pipe. Finally, the energy of the fluid is converted into electricity using turbine or organic rankine cycle (ORC). The main feature of the system is the employment of side channels to increase the amount of thermal energy extracted. A finite difference computer model is developed to solve the heat transport equation. The numerical model was employed to evaluate the performance of the design. The major goal was to optimize the output power as a function of parameters such as thermal diffusivity of the rock, depth of the main well, number and length of lateral channels. The sustainable lifetime of the system for a target output power of 2 MW has been calculated for deep geothermal systems with drilling depths of 8000 and 10000 meters, and a financial analysis has been performed to evaluate the economic feasibility of the system for a practical range of geothermal parameters. Results show promising an outlook for deep geothermal systems for practical applications.

Effect of Hydrogen Post-Annealing on Transparent Conductive ITO/Ga2O3 Bi-Layer Films for Deep Ultraviolet Light-Emitting Diodes.

PubMed

Kim, Kyeong Heon; Kim, Su Jin; Park, Sang Young; Kim, Tae Geun

2015-10-01

The effect of hydrogen post-annealing on the electrical and optical properties of ITO/Ga2O bi-layer films, deposited by RF magnetron sputtering, is investigated for potential applications to transparent conductive electrodes of ultraviolet (UV) light-emitting diodes. Three samples--an as-deposited sample and two samples post-annealed in N2 gas and N2-H2 gas mixture--were prepared and annealed at different temperatures ranging from 100 °C to 500 °C for comparison. Among these samples, the sample annealed at 300 °C in a mixture of N2 and H2 gases shows the lowest sheet resistance of 301.3 Ω/square and a high UV transmittance of 87.1% at 300 nm.

Electromagnetic study of lithospheric structure in the marginal zone of East European Craton in NW Poland

NASA Astrophysics Data System (ADS)

Jóźwiak, Waldemar

2013-10-01

The marginal zone of the East European Platform, an area of key importance for our understanding of the geotectonic history of Europe, has been a challenge for geophysicists for many years. The basic research method is seismic survey, but many important data on physical properties and structure of the lithosphere may also be provided by the electromagnetic methods. In this paper, results of deep basement study by electromagnetic methods performed in Poland since the mid-1960s are presented. Over this time, several hundred long-period soundings have been executed providing an assessment of the electric conductivity distribution in the crust and upper mantle. Numerous 1D, 2D, and pseudo-3D electric conductivity models were constructed, and a new interpretation method based on Horizontal Magnetic Tensor analysis has been applied recently. The results show that the contact zone is of lithospheric discontinuity character and there are distinct differences in geoelectric structures between the Precambrian Platform, transitional zone (TESZ), and the Paleozoic Platform. The wide-spread conducting complexes in the crust with integral conductivity values reaching 10 000 S at 20-30 km depths are most spectacular. They are most likely consequences of geological processes related to Caledonian and Variscan orogenesis. The upper mantle conductivity is also variable, the thickness of high-resistive lithospheric plates ranging from 120-140 km under the Paleozoic Platform to 220-240 km under the East European Platform.

Resistivity structures across the Humboldt River basin, north-central Nevada

USGS Publications Warehouse

Rodriguez, Brian D.; Williams, Jackie M.

2002-01-01

Magnetotelluric data collected along five profiles show deep resistivity structures beneath the Battle Mountain-Eureka and Carlin gold trends in north-central Nevada, which appear consistent with tectonic breaks in the crust that possibly served as channels for hydrothermal fluids. It seems likely that gold deposits along these linear trends were, therefore, controlled by deep regional crustal fault systems. Two-dimensional resistivity modeling of the magnetotelluric data generally show resistive (30 to 1,000 ohm-m) crustal blocks broken by sub-vertical, two-dimensional, conductive (1 to 10 ohmm) zones that are indicative of large-scale crustal fault zones. These inferred fault zones are regional in scale, trend northeast-southwest, north-south, and northwest-southeast, and extend to mid-crustal (20 km) depths. The conductors are about 2- to 15-km wide, extend from about 1 to 4 km below the surface to about 20 km depth, and show two-dimensional electrical structure. By connecting the locations of similar trending conductors together, individual regional crustal fault zones within the upper crust can be inferred that range from about 4- to 10-km wide and about 30- to 150-km long. One of these crustal fault zones coincides with the Battle Mountain-Eureka mineral trend. The interpreted electrical property sections also show regional changes in the resistive crust from south to north. Most of the subsurface in the upper 20 km beneath Reese River Valley and southern Boulder Valley are underlain by rock that is generally more conductive than the subsurface beneath Kelly Creek Basin and northern Boulder Valley. This suggests that either elevated-temperature or high-salinity fluids, alteration, or carbonaceous rocks are more pervasive in the more conductive area (Battle Mountain Heat-Flow High), which implies that the crust beneath these valleys is either more fractured or has more carbonaceous rocks than in the area surveyed along the 41st parallel.

Verification of an optimized stimulation point on the abdominal wall for transcutaneous neuromuscular electrical stimulation for activation of deep lumbar stabilizing muscles.

PubMed

Baek, Seung Ok; Cho, Hee Kyung; Jung, Gil Su; Son, Su Min; Cho, Yun Woo; Ahn, Sang Ho

2014-09-01

Transcutaneous neuromuscular electrical stimulation (NMES) can stimulate contractions in deep lumbar stabilizing muscles. An optimal protocol has not been devised for the activation of these muscles by NMES, and information is lacking regarding an optimal stimulation point on the abdominal wall. The goal was to determine a single optimized stimulation point on the abdominal wall for transcutaneous NMES for the activation of deep lumbar stabilizing muscles. Ultrasound images of the spinal stabilizing muscles were captured during NMES at three sites on the lateral abdominal wall. After an optimal location for the placement of the electrodes was determined, changes in the thickness of the lumbar multifidus (LM) were measured during NMES. Three stimulation points were investigated using 20 healthy physically active male volunteers. A reference point R, 1 cm superior to the iliac crest along the midaxillary line, was used. Three study points were used: stimulation point S1 was located 2 cm superior and 2 cm medial to the anterior superior iliac spine, stimulation point S3 was 2 cm below the lowest rib along the same sagittal plane as S1, and stimulation point S2 was midway between S1 and S3. Sessions were conducted stimulating at S1, S2, or S3 using R for reference. Real-time ultrasound imaging (RUSI) of the abdominal muscles was captured during each stimulation session. In addition, RUSI images were captured of the LM during stimulation at S1. Thickness, as measured by RUSI, of the transverse abdominis (TrA), obliquus internus, and obliquus externus was greater during NMES than at rest for all three study points (p<.05). Transverse abdominis was significantly stimulated more by NMES at S1 than at the other points (p<.05). The LM thickness was also significantly greater during NMES at S1 than at rest (p<.05). Neuromuscular electrical stimulation at S1 optimally activated deep spinal stabilizing muscles, TrA and LM, as evidenced by RUSI. The authors recommend this optimal stimulation point be used for NMES in the course of lumbar spine stabilization training in patients having difficulty initiating contraction of these muscles. Copyright © 2014 Elsevier Inc. All rights reserved.

Report on the survey for electrostatic discharges on Mars using NASA's Deep Space Network (DSN)

NASA Astrophysics Data System (ADS)

Arabshahi, S.; Majid, W.; Geldzahler, B.; Kocz, J.; Schulter, T.; White, L.

2017-12-01

Mars atmosphere has strong dust activity. It is suggested that the larger regional storms are capable of producing electric fields large enough to initiate electrostatic discharges. The storms have charging process similar to terrestrial dust devils and have hot cores and complicated vortex winds similar to terrestrial thunderstorms. However, due to uncertainties in our understanding of the electrical environment of the storms and absence of related in-situ measurements, the existence (or non-existence) of such electrostatic discharges on the planet is yet to be confirmed. Knowing about the electrical activity on Mars is essential for future human explorations of the planet. We have recently launched a long-term monitoring campaign at NASA's Madrid Deep Space Communication Complex (MDSCC) to search for powerful discharges on Mars. The search occurs during routine tracking of Mars orbiting spacecraft by Deep Space Network (DSN) radio telescope. In this presentation, we will report on the result of processing and analysis of the data from the first six months of our campaign.

Designing across Ages: Multi-Agent-Based Models and Learning Electricity

ERIC Educational Resources Information Center

Sengupta, Pratim

2009-01-01

Electricity is regarded as one of the most challenging topics for students at all levels--middle school--college (Cohen, Eylon, & Ganiel, 1983; Belcher & Olbert, 2003; Eylon & Ganiel, 1990; Steinberg et al., 1985). Several researchers have suggested that naive misconceptions about electricity stem from a deep incommensurability (Slotta & Chi,…

U.S. electric power sector transitions required to achieve 80% reductions in economy-wide greenhouse gas emissions: Results based on a state-level model of the U.S. energy system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iyer, Gokul C.; Clarke, Leon E.; Edmonds, James A.

The United States has articulated a deep decarbonization strategy for achieving a reduction in economy-wide greenhouse gas (GHG) emissions of 80% below 2005 levels by 2050. Achieving such deep emissions reductions will entail a major transformation of the energy system and of the electric power sector in particular. , This study uses a detailed state-level model of the U.S. energy system embedded within a global integrated assessment model (GCAM-USA) to demonstrate pathways for the evolution of the U.S. electric power sector that achieve 80% economy-wide reductions in GHG emissions by 2050. The pathways presented in this report are based onmore » feedback received during a workshop of experts organized by the U.S. Department of Energy’s Office of Energy Policy and Systems Analysis. Our analysis demonstrates that achieving deep decarbonization by 2050 will require substantial decarbonization of the electric power sector resulting in an increase in the deployment of zero-carbon and low-carbon technologies such as renewables and carbon capture utilization and storage. The present results also show that the degree to which the electric power sector will need to decarbonize and low-carbon technologies will need to deploy depends on the nature of technological advances in the energy sector, the ability of end-use sectors to electrify and level of electricity demand.« less

Electromagnetic receiver with capacitive electrodes and triaxial induction coil for tunnel exploration

NASA Astrophysics Data System (ADS)

Kai, Chen; Sheng, Jin; Wang, Shun

2017-09-01

A new type of electromagnetic (EM) receiver has been developed by integrating four capacitive electrodes and a triaxial induction coil with an advanced data logger for tunnel exploration. The new EM receiver can conduct EM observations in tunnels, which is one of the principal goals of surface-tunnel-borehole EM detection for deep ore deposit mapping. The use of capacitive electrodes enables us to record the electrical field (E-field) signals from hard rock surfaces, which are high-resistance terrains. A compact triaxial induction coil integrates three independent induction coils for narrow-tunnel exploration applications. A low-time-drift-error clock source is developed for tunnel applications where GPS signals are unavailable. The three main components of our tunnel EM receiver are: (1) four capacitive electrodes for measuring the E-field signal without digging in hard rock regions; (2) a triaxial induction coil sensor for audio-frequency magnetotelluric and controlled-source audio-frequency magnetotelluric signal measurements; and (3) a data logger that allows us to record five-component MT signals with low noise levels, low time-drift-error for the clock source, and high dynamic range. The proposed tunnel EM receiver was successfully deployed in a mine that exhibited with typical noise characteristics. [Figure not available: see fulltext. Caption: The new EM receiver can conduct EM observations in tunnels, which is one of the principal goals of the surface-tunnel-borehole EM (STBEM) detection for deep ore deposit mapping. The use of a capacitive electrode enables us to record the electrical field (E-field) signals from hard rock surfaces. A compact triaxial induction coil integrated three induction coils, for narrow-tunnel applications.

Double-injection, deep-impurity switch development

NASA Technical Reports Server (NTRS)

Selim, F. A.; Whitson, D. W.

1983-01-01

The overall objective of this program is the development of device design and process techniques for the fabrication of a double-injection, deep-impurity (DI)(2) silicon switch that operates in the 1-10 kV range with conduction current of 10 and 1A, respectively. Other major specifications include a holding voltage of 0 to 5 volts at 1 A anode current, 10 microsecond switching time, and power dissipation of 50 W at 75 C. This report describes work that shows how the results obtained at the University of Cincinnati under NASA Grant NSG-3022 have been applied to larger area and higher voltage devices. The investigations include theoretical, analytical, and experimental studies of device design and processing. Methods to introduce deep levels, such as Au diffusion and electron irradiation, have been carried out to "pin down' the Fermi level and control device-switching characteristics. Different anode, cathode, and gate configurations are presented. Techniques to control the surface electric field of planar structures used for (DI)(2) switches are examined. Various sections of this report describe the device design, wafer-processing techniques, and various measurements which include ac and dc characteristics, 4-point probe, and spreading resistance.

The Power Supply And Control Unit For The HEMP Thruster

NASA Astrophysics Data System (ADS)

Brag, Rafael; Lenz, Werner; Huther, Andreas; Herty, Frank

2011-10-01

In the recent years, Astrium GmbH started to develop electronics to control and supply Electric Propulsion systems or corresponding components. One of the developments is a Power Supply and Control Unit (PSCU) for the Thales Electron Devices development "High Efficiency Multistage Plasma Thruster" (HEMP- T). The PSCU is developed, manufactured and tested on the Astrium southern Germany site in Friedrichshafen. The first application is the SGEO Satellite (HISPASAT- 1), where the In-Orbit Demonstration (IOD) of the HEMP Thruster system will prove the success of the product. Astrium conducted several coupling tests during the PSCU development especially concentrated on *Thruster electrical I/F parameters *Neutralizer electrical I/F parameters *Flow Control I/F parameters Results of these tests were used to refine the specification and adapt the PSCU drivers and control algorithms. Furthermore, the tests results gave Thales and Astrium the possibility for a deep understanding of the interaction between the physics and the electronics. The paper presents an overview of the PSCU topology, key features, technical and development logic details as well as a view into the control capabilities of the PSCU.

Correlation between the transport mechanisms in conductive filaments inside Ta2O5-based resistive switching devices and in substoichiometric TaOx thin films

NASA Astrophysics Data System (ADS)

Rosário, Carlos M. M.; Thöner, Bo; Schönhals, Alexander; Menzel, Stephan; Wuttig, Matthias; Waser, Rainer; Sobolev, Nikolai A.; Wouters, Dirk J.

2018-05-01

Conductive filaments play a key role in redox-based resistive random access memory (ReRAM) devices based on the valence change mechanism, where the change of the resistance is ascribed to the modulation of the oxygen content in a local region of these conductive filaments. However, a deep understanding of the filaments' composition and structure is still a matter of debate. We approached the problem by comparing the electronic transport, at temperatures from 300 K down to 2 K, in the filaments and in TaOx films exhibiting a substoichiometric oxygen content. The filaments were created in Ta (15 nm)/Ta2O5 (5 nm)/Pt crossbar ReRAM structures. In the TaOx thin films with various oxygen contents, the in-plane transport was studied. There is a close similarity between the electrical properties of the conductive filaments in the ReRAM devices and of the TaOx films with x ˜ 1, evidencing also no dimensionality difference for the electrical transport. More specifically, for both systems there are two different conduction processes: one in the higher temperature range (from 50 K up to ˜300 K), where the conductivity follows a √{ T } dependence, and one at lower temperatures (<50 K), where the conductivity follows the exp(-1 / √{ T } ) dependence. This suggests a strong similarity between the material composition and structure of the filaments and those of the substoichiometric TaOx films. We also discuss the temperature dependence of the conductivity in the framework of possible transport mechanisms, mainly of those normally observed for granular metals.

Analysis of deep seismic reflection and other data from the southern Washington Cascades

NASA Astrophysics Data System (ADS)

Stanley, W. D.; Johnson, S. Y.

Limited possibilities exist for new hydrocarbon exploration regimes in the Pacific Northwest. Extensive geophysical studies have been used to outline a proposed sedimentary basin hidden beneath volcanic rocks of the Cascades region of southwestern Washington (Stanley et. al, 1992, AAPG Bull. 76, 1569-1585). Electrical geophysical imaging using the magnetotelluric (MT) method first detected thick, electrically conductive sequences believed to represent late Cretaceous to Oligocene marine sedimentary rocks. The conductive section occurs at depths from about 1 km to 10 km in the area west of a line between Mt. Rainier and Mt. Adams, extending westward to a line between Mt. St. Helens and just west of Morton, WA. The conductive rocks reaches thicknesses as great as 10 km. The anomalous rocks appear to be very near the surface in the axis of anticanes that bring Eocene marine shales to shallow depths. Careful consideration of physical properties and the correspondence of the morphology of the units to known fold sets suggests that the high conductivities are related to lithologic/stratigraphic units rather than to variations in physical properties. Our preference for the lithology of the anomalous section, based upon a study of regional geology and structure, is one dominated by marine shales of Eocene and older age. Other possible lithologies that have been evaluated for the conductive section include nonmarine sedimentary units of Tertiary age, highly altered volcanic flows, and pre-Tertiary metasedimentary rocks with large percentages of graphite. We refer to this anomalously conductive region as the southern Washington Cascades conductor (SWCC).

Marine magnetotellurics imaged no distinct plume beneath the Tristan da Cunha hotspot in the southern Atlantic Ocean

NASA Astrophysics Data System (ADS)

Baba, Kiyoshi; Chen, Jin; Sommer, Malte; Utada, Hisashi; Geissler, Wolfram H.; Jokat, Wilfried; Jegen, Marion

2017-10-01

The Tristan da Cunha (TDC) is a volcanic island located above a prominent hotspot in the Atlantic Ocean. Many geological and geochemical evidences support a deep origin of the mantle material feeding the hotspot. However, the existence of a plume has not been confirmed as an anomalous structure in the mantle resolved by geophysical data because of lack of the observations in the area. Marine magnetotelluric and seismological observations were conducted in 2012-2013 to examine the upper mantle structure adjacent to TDC. The electrical conductivity structure of the upper mantle beneath the area was investigated in this study. Three-dimensional inversion analysis depicted a high conductive layer at 120 km depth but no distinct plume-like vertical structure. The conductive layer is mostly flat independently on seafloor age and bulges upward beneath the lithospheric segment where the TDC islands are located compared to younger segment south of the TDC Fracture Zone, while the bathymetry is rather deeper than prediction for the northern segment. The apparent inconsistency between the absence of vertical structure in this study and geochemical evidences on deep origin materials suggests that either the upwelling is too small and/or weak to be resolved by the current data set or that the upwelling takes place elsewhere outside of the study area. Other observations suggest that 1) the conductivity of the upper mantle can be explained by the fact that the mantle above the high conductivity layer is depleted in volatiles as the result of partial melting beneath the spreading ridge, 2) the potential temperature of the segments north of the TDC Fracture Zone is lower than that of the southern segment at least during the past 30 Myr.

Subsurface Rock Physical Properties by Downhole Loggings - Case Studies of Continental Deep Drilling in Kanto Distinct, Japan

NASA Astrophysics Data System (ADS)

Omura, K.

2014-12-01

In recent years, many examples of physical logging have been carried out in deep boreholes. The loggings are direct in-situ measurements of rock physical properties under the ground. They provide significant basic data for the geological, geophysical and geotechnical investigations, e.g., tectonic history, seismic wave propagation, and ground motion prediction. Since about 1980's, Natl. Res. Inst. for Earth Sci. and Disast. Prev. (NIED) dug deep boreholes (from 200m to 3000m depth) in sedimentary basin of Kanto distinct, Japan, for purposes of installing seismographs and hydrological instruments, and in-situ stress and pore pressure measurements. At that time, downhole physical loggings were conducted in the boreholes: spontaneous potential, electrical resistance, elastic wave velocity, formation density, neutron porosity, total gamma ray, caliper, temperature loggings. In many cases, digital data values were provided every 2m or 1m or 0.1m. In other cases, we read printed graphs of logging plots and got digital data values. Data from about 30 boreholes are compiled. Especially, particular change of logging data at the depth of an interface between a shallow part (soft sedimentary rock) and a base rock (equivalent to hard pre-Neogene rock) is examined. In this presentation, the correlations among physical properties of rock (especially, formation density, elastic wave velocity and electrical resistance) are introduced and the relation to the lithology is discussed. Formation density, elastic wave velocity and electric resistance data indicate the data are divide in two groups that are higher or lower than 2.5g/cm3: the one correspond to a shallow part and the other correspond to a base rock part. In each group, the elastic wave velocity and electric resistance increase with increase of formation density. However the rates of increases in the shallow part are smaller than in the base rock part. The shallow part has lower degree of solidification and higher porosity than that in the base rock part. It appears differences in the degree of solidification and/or porosity are related to differences in the increasing rates. The present data show that the physical logging data are effective information to explore where the base rock is and what properties of the base rock are different from those in the shallow part.

Comparison of the induced fields using different coil configurations during deep transcranial magnetic stimulation.

PubMed

Lu, Mai; Ueno, Shoogo

2017-01-01

Stimulation of deeper brain structures by transcranial magnetic stimulation (TMS) plays a role in the study of reward and motivation mechanisms, which may be beneficial in the treatment of several neurological and psychiatric disorders. However, electric field distributions induced in the brain by deep transcranial magnetic stimulation (dTMS) are still unknown. In this paper, the double cone coil, H-coil and Halo-circular assembly (HCA) coil which have been proposed for dTMS have been numerically designed. The distributions of magnetic flux density, induced electric field in an anatomically based realistic head model by applying the dTMS coils were numerically calculated by the impedance method. Results were compared with that of standard figure-of-eight (Fo8) coil. Simulation results show that double cone, H- and HCA coils have significantly deep field penetration compared to the conventional Fo8 coil, at the expense of induced higher and wider spread electrical fields in superficial cortical regions. Double cone and HCA coils have better ability to stimulate deep brain subregions compared to that of the H-coil. In the mean time, both double cone and HCA coils increase risk for optical nerve excitation. Our results suggest although the dTMS coils offer new tool with potential for both research and clinical applications for psychiatric and neurological disorders associated with dysfunctions of deep brain regions, the selection of the most suitable coil settings for a specific clinical application should be based on a balanced evaluation between stimulation depth and focality.

Electrical burns in Chinese fishermen using graphite rods under high-voltage cables.

PubMed

Wang, Fei; Chen, Xu-Lin; Wang, Yong-Jie; Chen, Xia-Ying; Guo, Feng; Sun, Ye-Xiang

2007-01-01

The 42 patients admitted to our Burn Center from January 1, 1994 to December 31, 2005, with electrical and fire burn injuries caused by electricity-conducting graphite-carbon fishing rods touching overhead high voltage electrical lines were epidemiologically studied retrospectively. All patients were men, with a mean age of 40.33 years. The majority of patients (59.5%) were burned with less than 10%, mostly deep burns. The hand was the predominant electricity "entry" point and foot was the most frequent "exit" point. Admissions increased from 5 in 6 years, 1994 to 2000, to 15 in 3 years, 2000 through 2002, to 22 cases in 3 years, 2003 through 2005. Spring and fall, and months May and October were times of highest incidence. The treatment was complex, difficult, long, and costly. Thirty-eight patients (90.4%) required operations, including early excision and graft (34 patients), and amputation (14 patients). Two patients had an inhalation injury that necessitated a tracheostomy and four victims had additional skin and soft-tissue injury. Thirty-two patients had a record of unconsciousness immediately after the electrical injury and atrial premature beats were a frequently found arrhythmia. A significant (P <.01) increase in serum creatine kinase MB fraction was found in 11 patients. The mean time in hospital of the survivors was 28.97 days. Acute renal failure was the commonest complication and one patient died of sepsis with giving a mortality rate of 2.4%. Caution and preventive measures are warranted while fishing near electrical wires, and improvements in electrical burn treatment are needed.

A deep crustal fluid channel into the San Andreas Fault system near Parkfield, California

USGS Publications Warehouse

Becken, M.; Ritter, O.; Park, S.K.; Bedrosian, P.A.; Weckmann, U.; Weber, M.

2008-01-01

Magnetotelluric (MT) data from 66 sites along a 45-km-long profile across the San Andreas Fault (SAF) were inverted to obtain the 2-D electrical resistivity structure of the crust near the San Andreas Fault Observatory at Depth (SAFOD). The most intriguing feature of the resistivity model is a steeply dipping upper crustal high-conductivity zone flanking the seismically defined SAF to the NE, that widens into the lower crust and appears to be connected to a broad conductivity anomaly in the upper mantle. Hypothesis tests of the inversion model suggest that upper and lower crustal and upper-mantle anomalies may be interconnected. We speculate that the high conductivities are caused by fluids and may represent a deep-rooted channel for crustal and/or mantle fluid ascent. Based on the chemical analysis of well waters, it was previously suggested that fluids can enter the brittle regime of the SAF system from the lower crust and mantle. At high pressures, these fluids can contribute to fault-weakening at seismogenic depths. These geochemical studies predicted the existence of a deep fluid source and a permeable pathway through the crust. Our resistivity model images a conductive pathway, which penetrates the entire crust, in agreement with the geochemical interpretation. However, the resistivity model also shows that the upper crustal branch of the high-conductivity zone is located NE of the seismically defined SAF, suggesting that the SAF does not itself act as a major fluid pathway. This interpretation is supported by both, the location of the upper crustal high-conductivity zone and recent studies within the SAFOD main hole, which indicate that pore pressures within the core of the SAF zone are not anomalously high, that mantle-derived fluids are minor constituents to the fault-zone fluid composition and that both the volume of mantle fluids and the fluid pressure increase to the NE of the SAF. We further infer from the MT model that the resistive Salinian block basement to the SW of the SAFOD represents an isolated body, being 5-8km wide and reaching to depths >7km, in agreement with aeromagnetic data. This body is separated from a massive block of Salinian crust farther to the SW. The NE terminus of resistive Salinian crust has a spatial relationship with a near-vertical zone of increased seismic reflectivity ???15km SW of the SAF and likely represents a deep-reaching fault zone. ?? 2008 The Authors Journal compilation ?? 2008 RAS.

Van Allen Probes Measurements of Energetic Particle Deep Penetration Into the Low L Region (L < 4) During the Storm on 8 April 2016

NASA Astrophysics Data System (ADS)

Zhao, H.; Baker, D. N.; Califf, S.; Li, X.; Jaynes, A. N.; Leonard, T.; Kanekal, S. G.; Blake, J. B.; Fennell, J. F.; Claudepierre, S. G.; Turner, D. L.; Reeves, G. D.; Spence, H. E.

2017-12-01

Using measurements from the Van Allen Probes, a penetration event of tens to hundreds of keV electrons and tens of keV protons into the low L shells (L < 4) is studied. Timing and magnetic local time (MLT) differences of energetic particle deep penetration are unveiled and underlying physical processes are examined. During this event, both proton and electron penetrations are MLT asymmetric. The observed MLT difference of proton penetration is consistent with convection of plasma sheet protons, suggesting enhanced convection during geomagnetic active times to be the cause of energetic proton deep penetration during this event. The observed MLT difference of tens to hundreds of keV electron penetration is completely different from tens of keV protons and cannot be well explained by inward radial diffusion, convection of plasma sheet electrons, or transport of trapped electrons by enhanced convection electric field represented by the Volland-Stern model or a uniform dawn-dusk electric field model based on the electric field measurements. It suggests that the underlying physical mechanism responsible for energetic electron deep penetration, which is very important for fully understanding energetic electron dynamics in the low L shells, should be MLT localized.

Propulsion Utilizing Laser-Driven Ponderomotive Fields for Deep-Space Missions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, George J.; Gilland, James H.

The generation of large amplitude electric fields in plasmas by high-power lasers has been studied for several years in the context of high-energy particle acceleration. Fields on the order of GeV/m are generated in the plasma wake of the laser by non-linear ponderomotive forces. The laser fields generate longitudinal and translational electron plasma waves with phase velocities close to the speed of light. These fields and velocities offer the potential to revolutionize spacecraft propulsion, leading to extended deep space robotic probes. Based on these initial calculations, plasma acceleration by means of laser-induced ponderomotive forces appears to offer significant potential formore » spacecraft propulsion. Relatively high-efficiencies appear possible with proper beam conditioning, resulting in an order of magnitude more thrust than alternative concepts for high I{sub SP} (>10{sup 5} s) and elimination of the primary life-limiting erosion phenomena associated with conventional electric propulsion systems. Ponderomotive propulsion readily lends itself to beamed power which might overcome some of the constraints of power-limited propulsion concepts. A preliminary assessment of the impact of these propulsion systems for several promising configurations on mission architectures has been conducted. Emphasizing interstellar and interstellar-precursor applications, performance and technical requirements are identified for a number of missions. The use of in-situ plasma and gas for propellant is evaluated as well.« less

Does EMF Emitted from In Situ Subsea Power Cables Affect the Composition of Deep Benthic Fish and Invertebrate Communities?

NASA Astrophysics Data System (ADS)

Bull, A. S.; Nishimoto, M.; Love, M.; Schroeder, D. M.

2016-02-01

A network of power cables is an important component of any offshore renewable energy generation facilities (e.g., wind and wave). The cables laid on the seafloor carry current that produces both electric and magnetic fields; the magnetic field, here called an electromagnetic field (EMF), is what is emitted from shielded cables. The cables, themselves, add hard, low-relief structure to what is typically soft-bottom habitat (mud or sand). Given that laboratory experiments show EMF can affect the behavior of some marine vertebrates and invertebrates, concern is raised over the potential ecological impacts of in situ power cables. Here we report an unusual comparative study of the effect of EMF emitted from in situ power cables on the fish and invertebrate communities of the deep coastal shelf environment. In the Santa Barbara Channel of southern California, subsea power cables, similar to those used in the offshore renewable energy industry, transmit electricity from shore to offshore oil and gas production platforms. A non-energized cable in the vicinity of energized cables afforded us the unusual opportunity to control for the effect of cable as hard, low relief habitat. We conducted three annual submersible surveys in October, 2012- 2014, at depths from 75 m to 210 m. We present results comparing observations along the energized and nonenergized cables and on the adjacent natural substrate.

Cavity detection and delineation research. Part 1: Microgravimetric and magnetic surveys: Medford Cave Site, Florida

NASA Astrophysics Data System (ADS)

Butler, D. K.

1982-03-01

This report reviews the scope of a research effort initiated in 1974 at the U.S. Army Engineer Waterways Experiment Station with the objectives of (a) assessing the state of the art in geophysical cavity detection and delineation methodology and (b) developing new methods and improving or adapting old methods for application to cavity detection and delineation. Two field test sites were selected: (a) the Medford Cave site with a relatively shallow (10- to 50-ft-deep) air-filled cavity system and (b) the Manatee Springs site with a deeper (approximately 100-ft-deep) water-filled cavity system. Results of field studies at the Medford Cave site are presented in this report: (a) the site geology, (b) the site topographic survey, (c) the site drilling program (boreholes for geophysical tests, for determination of a detailed geological cross section, and for verification of geophysical anomalies), (d) details of magnetic and microgravimetric surveys, and (e) correlation of geophysical results with known site geology. Qualitative interpretation guidelines using complementary geophysical techniques for site investigations in karst regions are presented. Including the results of electrical resistivity surveys conducted at the Medford Cave site, the qualitative guidelines are applied to four profile lines, and drilling locations are indicated on the profile plots of gravity, magnetic, and electrical resistivity data. Borehole logs are then presented for comparison with the predictions of the qualitative interpretation guidelines.

Proceedings of a pressure transducer-packer workshop, June 25-28, 1991

USGS Publications Warehouse

Latkovich, V. J.

1993-01-01

The U.S. Geological Survey conducted its first Pressure Transducer-Packer Workshop in Denver, Colorado, June 25-28, 1991. Nineteen attendees from the Survey, Environment Canada, academia, and the private sector presented papers concerning their experiences with the use of transducers and packers in hydrogeologic investigations. Workshop partici- pants concluded that fixed-head packers are generally more reliable than other types and that there is a need for a wet/wet transducer for deep wells. The group recommended that simple downhole technology be used, that only rugged commercially available packers be purchased, and that it is imperative electrical connections and transducer electronics be kept dry. (USGS)

Thermal Properties of Double-Aluminized Kapton at Low Temperatures

NASA Technical Reports Server (NTRS)

Tuttle, J.; DiPirro, M.; Canavan, E.; Hait, T.

2007-01-01

Double-aluminized kapton (DAK) is commonly used in multi-layer insulation blankets in cryogenic systems. NASA plans to use individual DAK sheets in lightweight deployable shields for satellites carrying instruments. A set of these shields will reflect away thermal radiation from the sun, the earth, and the instrument's warm side and allow the instrument's cold side to radiate its own heat to deep space. In order to optimally design such a shield system, it is important to understand the thermal characteristics of DAK down to low temperatures. We describe experiments which measured the thermal conductivity and electrical resistivity down to 4 Kelvin and the emissivity down to 10 Kelvin.

Origin and assessment of deep groundwater inflow in the Ca' Lita landslide using hydrochemistry and in situ monitoring

NASA Astrophysics Data System (ADS)

Cervi, F.; Ronchetti, F.; Martinelli, G.; Bogaard, T. A.; Corsini, A.

2012-06-01

Changes in soil water content, groundwater flow and a rise in pore water pressure are well-known causal or triggering factors for hillslope instability. Rainfall and snowmelt are generally assumed as the only sources of groundwater recharge. This assumption neglects the role of deep water inflow in highly tectonized areas, a factor that can influence long-term pore-pressure regimes and play a role on local slope instability. This paper aims to assess the origin of groundwater in the Ca' Lita landslide (northern Italian Apennines) and to qualify and quantify the aliquot attributable to deep water inflow. The research is essentially based on in situ monitoring and hydrochemical analyses. It involved 5 yr of continuous monitoring of groundwater levels, electrical conductivity and temperature, and with groundwater sampling followed by determination of major ions, tracers (such as Boron and Strontium), and isotopes (Oxygen, Deuterium, Tritium). Leaching experiments on soil samples and water recharge estimation were also carried out. Results show that the groundwater balance in the Ca' Lita landslide must take into account an inflow of highly mineralized Na-SO4 water (more than 9500 μS cm-1) with non-negligible amounts of Chloride (up to 800 mg l-1). The deep water inflow recharges the aquifer hosted in the bedrock underlying the sliding surface (at a rate of about 7800-17 500 m3 yr-1). It also partly recharges the landslide body, where the hydrochemical imprint of deep water mixed with rainfall and snowmelt water was observed. This points to a probable influence of deep water inflow on the mobility of the Ca' Lita landslide, a finding that could be applicable to other large landslides occurring in highly tectonized areas in the northern Apennines or in other mountain chains.

Metallic Junction Thermoelectric Device Simulations

NASA Technical Reports Server (NTRS)

Duzik, Adam J.; Choi, Sang H.

2017-01-01

Thermoelectric junctions made of semiconductors have existed in radioisotope thermoelectric generators (RTG) for deep space missions, but are currently being adapted for terrestrial energy harvesting. Unfortunately, these devices are inefficient, operating at only 7% efficiency. This low efficiency has driven efforts to make high-figure-of-merit thermoelectric devices, which require a high electrical conductivity but a low thermal conductivity, a combination that is difficult to achieve. Lowered thermal conductivity has increased efficiency, but at the cost of power output. An alternative setup is to use metallic junctions rather than semiconductors as thermoelectric devices. Metals have orders of magnitude more electrons and electronic conductivities higher than semiconductors, but thermal conductivity is higher as well. To evaluate the viability of metallic junction thermoelectrics, a two dimensional heat transfer MATLAB simulation was constructed to calculate efficiency and power output. High Seebeck coefficient alloys, Chromel (90%Ni-10%Cr) and Constantan (55%Cu-45%Ni), produced efficiencies of around 20-30%. Parameters such as the number of layers of junctions, lateral junction density, and junction sizes for both series- and parallel-connected junctions were explored.

Fully Implantable Deep Brain Stimulation System with Wireless Power Transmission for Long-term Use in Rodent Models of Parkinson's Disease.

PubMed

Heo, Man Seung; Moon, Hyun Seok; Kim, Hee Chan; Park, Hyung Woo; Lim, Young Hoon; Paek, Sun Ha

2015-03-01

The purpose of this study to develop new deep-brain stimulation system for long-term use in animals, in order to develop a variety of neural prostheses. Our system has two distinguished features, which are the fully implanted system having wearable wireless power transfer and ability to change the parameter of stimulus parameter. It is useful for obtaining a variety of data from a long-term experiment. To validate our system, we performed pre-clinical test in Parkinson's disease-rat models for 4 weeks. Through the in vivo test, we observed the possibility of not only long-term implantation and stability, but also free movement of animals. We confirmed that the electrical stimulation neither caused any side effect nor damaged the electrodes. We proved possibility of our system to conduct the long-term pre-clinical test in variety of parameter, which is available for development of neural prostheses.

[Observation on therapeutic effect of electroacupuncture at Tianshu (ST 25) with deep needling technique on functional constipation].

PubMed

Wang, Cheng-Wei; He, Hong-Bo; Li, Ning; Wen, Qian; Liu, Zhi-Shun

2010-09-01

To probe into a better therapeutic method for functional constipation. Ninety-five cases of functional constipation were randomly divided into deep puncture at ST 25 group (48 cases), shallow puncture at ST 25 group (24 cases) and medication group (23 cases). In deep puncture at ST 25 group, Tianshu (ST 25) was punctured deeply to the peritoneum, with electric stimulation. In shallow puncture at ST 25 group, Tianshu (ST 25) was punctured shallowly, 5 mm beneath the skin, with electric stimulation. In medication group, Duphalac was administered orally. These cases were treated continuously for 4 weeks in 3 groups and followed up for 6 months. It was to observe the numbers of person who had defecation 4 times a week, difference in weekly defecation frequency and the difference in the Cleveland Clinic Score (CCS). In deep puncture at ST 25 group, the frequency of weekly defecation and the numbers of person who had defecation 4 times a week increased and CCS decreased, which were similar to the efficacy in shallow puncture at ST 25 group (all P > 0.05). But the efficacy of both ST 25 groups was superior to that in medication group (both P < 0.05). In comparison, the deep puncture at ST 25 group acted more quickly than either shallow puncture at ST 25 group or medication group and its efficacy remained much longer. The deep puncture at ST 25 with electric stimulation presents similar efficacy on functional constipation as shallow puncture at ST 25, but it acts more quickly than shallow puncture at ST 25, both of them are more advantageous than medication and the long-term efficacy is better.

Electrically Anisotropic 35 Ma Pacific Lithosphere

NASA Astrophysics Data System (ADS)

Chesley, C. J.; Key, K.; Constable, S.; Behrens, J.; MacGregor, L.

2017-12-01

Geophysical studies of anisotropy in the oceanic lithosphere and asthenosphere can yield crucial insights into the processes of plate formation and evolution as the plate cools and thickens. While most previous studies have employed seismic methods to investigate anisotropy, here we examine the electrical conductivity anisotropy as constrained by controlled-source electromagnetic (CSEM) data collected during the Anisotropy and Physics of the Pacific Lithosphere Experiment (APPLE). Unlike passive magnetotelluric data, which are not particularly sensitive to the resistive part of the lithosphere or its anisotropy, CSEM data are highly sensitive to anisotropy in both the resistive crust and uppermost mantle. The APPLE data include a 30 km radius circular deep-tow of a Horizontal Electric Dipole (HED) transmitter around orthogonal pairs of HED receivers. The circular tow was optimized to measure azimuthal anisotropy, while radially oriented data at ranges from 14 to 70 km provided constraints on depth dependence of bulk conductivity. We inverted these data with a nonlinear anisotropic inversion that allows for laterally transverse isotropy, with the vertical plane of isotropy aligned orthogonal to the paleo-spreading direction. Our best model shows at least an order of magnitude resistivity difference between the paleo-spreading and paleo-ridge strike directions in both the crust and upper mantle. In the crust, conductivity is higher in the paleo-ridge and vertical directions. The opposite is true in the upper mantle, where conductivity is ten times higher in the paleo-spreading direction. Since the study area is centered on 35 Ma lithosphere, it is unlikely that melt plays a role in the observed anisotropy. Instead we propose that the crustal anisotropy is due to conductive clay minerals in normal faults promoted by hydration during paleo-extension close to the mid-ocean ridge. The upper mantle anisotropy potentially results from a crystal preferred orientation of olivine induced by shear deformation. These findings offer clues about the processes associated with oceanic spreading and may be of import to ophiolite studies.

Anomalously deep polarization in SrTiO3 (001) interfaced with an epitaxial ultrathin manganite film

DOE PAGES

Wang, Zhen; Tao, Jing; Yu, Liping; ...

2016-10-17

Using atomically-resolved imaging and spectroscopy, we reveal a remarkably deep polarization in non-ferroelectric SrTiO 3 near its interface with an ultrathin nonmetallic film of La 2/3Sr 1/3MnO 3. Electron holography shows an electric field near the interface in SrTiO 3, yielding a surprising spontaneous polarization density of ~ 21 μC/cm 2. Combining the experimental results with first principles calculations, we propose that the observed deep polarization is induced by the electric field originating from oxygen vacancies that extend beyond a dozen unit-cells from the interface, thus providing important evidence of the role of defects in the emergent interface properties ofmore » transition metal oxides.« less

Optical transitions of the silicon vacancy in 6H-SiC studied by positron annihilation spectroscopy

NASA Astrophysics Data System (ADS)

Arpiainen, S.; Saarinen, K.; Hautojärvi, P.; Henry, L.; Barthe, M.-F.; Corbel, C.

2002-08-01

Positron annihilation spectroscopy has been applied to identify Si and C vacancies as irradiation-induced defects in 6H-SiC. Si vacancies are shown to have ionization levels at EC-0.6 eV and EC-1.1 eV below the conduction-band edge EC by detecting changes of positron trapping under monochromatic illumination. These levels are attributed to (2-/1-) and (1-/0) ionizations of the isolated Si vacancy. In as-grown n-type 6H-SiC, a native defect complex involving VSi is shown to have an ionization level slightly closer to conduction band at roughly EC-0.3 eV. These results are used further to present microscopic interpretations to effects seen in optical-absorption spectra and to electrical levels observed previously by deep-level transient spectroscopy.

Updates to Enhanced Geothermal System Resource Potential Estimate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Augustine, Chad

The deep EGS electricity generation resource potential estimate maintained by the National Renewable Energy Laboratory was updated using the most recent temperature-at-depth maps available from the Southern Methodist University Geothermal Laboratory. The previous study dates back to 2011 and was developed using the original temperature-at-depth maps showcased in the 2006 MIT Future of Geothermal Energy report. The methodology used to update the deep EGS resource potential is the same as in the previous study and is summarized in the paper. The updated deep EGS resource potential estimate was calculated for depths between 3 and 7 km and is binned inmore » 25 degrees C increments. The updated deep EGS electricity generation resource potential estimate is 4,349 GWe. A comparison of the estimates from the previous and updated studies shows a net increase of 117 GWe in the 3-7 km depth range, due mainly to increases in the underlying temperature-at-depth estimates from the updated maps.« less

Update to Enhanced Geothermal System Resource Potential Estimate: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Augustine, Chad

2016-10-01

The deep EGS electricity generation resource potential estimate maintained by the National Renewable Energy Laboratory was updated using the most recent temperature-at-depth maps available from the Southern Methodist University Geothermal Laboratory. The previous study dates back to 2011 and was developed using the original temperature-at-depth maps showcased in the 2006 MIT Future of Geothermal Energy report. The methodology used to update the deep EGS resource potential is the same as in the previous study and is summarized in the paper. The updated deep EGS resource potential estimate was calculated for depths between 3 and 7 km and is binned inmore » 25 degrees C increments. The updated deep EGS electricity generation resource potential estimate is 4,349 GWe. A comparison of the estimates from the previous and updated studies shows a net increase of 117 GWe in the 3-7 km depth range, due mainly to increases in the underlying temperature-at-depth estimates from the updated maps.« less

Detectability of underground electrical cables junction with a ground penetrating radar: electromagnetic simulation and experimental measurements

NASA Astrophysics Data System (ADS)

Liu, Xiang; serhir, mohammed; kameni, abelin; lambert, marc; pichon, lionel

2016-04-01

For a company like Electricity De France (EDF), being able to detect accurately using non-destructive methods the position of the buried junction between two underground cables is a crucial issue. The junction is the linking part where most maintenance operations are carried out. The challenge of this work is to conduct a feasibility study to confirm or deny the relevance of Ground Penetrating Radar (GPR) to detect these buried junctions in their actual environment against clutter. Indeed, the cables are buried in inhomogeneous medium at around 80cm deep. To do this, the study is conducted in a numerical environment. We use the 3D simulation software CST MWS to model a GPR scenario. In this simulation, we place the already optimized bowtie antennas operating in the frequency band [0.5 GHz - 3 GHz] in front of wet soil (dispersive) and dry soil where the underground cable is placed at 80cm deep. We collect the amplitude and phase of the reflected waves in order to detect the contrast provoked by the geometric dimensions variation of the cable [1] (diameter of the cable is 48mm and the diameter of the junction 74mm). The use of an ultra-wideband antenna is necessary to reconcile resolution and penetration of electromagnetic waves in the medium to be characterized. We focus on the performance of the GPR method according to the characteristics of the surrounding medium in which the electric cables are buried, the polarization of the Tx and Rx antennas. The experimental measurement collected in the EDF site will be presented. The measured data are processed using the clutter reduction method based on digital filtering [2]. We aim at showing that using the developed bowtie antennas that the GPR technique is well adapted for the cable junction localization even in cluttered environment. References [1] D. J. Daniels, "Surface-Penetrating Radar", London, IEE 1996. [2] Potin, D.; Duflos, E.; Vanheeghe, P., "Landmines Ground-Penetrating Radar Signal Enhancement by Digital Filtering," in Geoscience and Remote Sensing, IEEE Transactions on , vol.44, no.9, pp.2393-2406, Sept. 2006 .

Learning Electricity with NIELS: Thinking with Electrons and Thinking in Levels

ERIC Educational Resources Information Center

Sengupta, Pratim; Wilensky, Uri

2009-01-01

Electricity is regarded as one of the most challenging topics for students of all ages. Several researchers have suggested that naive misconceptions about electricity stem from a deep incommensurability (Slotta and Chi 2006; Chi 2005) or incompatibility (Chi et al. 1994) between naive and expert knowledge structures. In this paper we argue that…

The study of the application of crystalline silicone solar cell type for a temporary flood camp

NASA Astrophysics Data System (ADS)

Hendarti, R.; Katarina, W.; Wangidjaja, W.

2017-12-01

During flood period, most of temporary evacuation shelters in Jakarta are lack in electricity because the local electricity company turned the electricity off to avoid any electrical problem because of the high water level over the flooded area. Whereas, the local electricity or the grid is the main energy source for the lighting and water pump machine, therefore the energy source becomes a significant issue during this period. Currently, the local government has already provided diesel generators to substitute the local grid when it is off, however, the amount of the generators is still limited. This study, therefore, investigated an alternative energy for the electricity, particularly solar energy and this paper presents an analysis of the Jakarta duration of sunshine during rainy seasons in order to investigate which Crystalline Silicone solar cell type that can be implemented optimally for energy supply in the period of flood evacuation as well as for the shelter. A deep analysis on literature review was conducted on the three types of Crystalline Silicone solar cell, Jakarta local weather. Furthermore, the standard of International Federation of Red Cross and Red Crescent Societies (IFRC) was also studied for the shelter design. The results of this study could be used as a reference for the local authority in providing the substitute energy supply in the temporary evacuation area during flood period in which the solar energy source could be also attached on the shelter.

Extensibility of Human Asteroid Mission to Mars and Other Destinations

NASA Technical Reports Server (NTRS)

McDonald, Mark A.; Caram, Jose M.; Lopez, Pedro; Hinkel, Heather D.; Bowie, Jonathan T.; Abell, Paul A.; Drake, Bret G.; Martinez, Roland M.; Chodas, Paul W.; Hack, Kurt;

Electrical Characterization of Irradiated Semiconducting Amorphous Hydrogenated Boron Carbide

NASA Astrophysics Data System (ADS)

Peterson, George Glenn

Semiconducting amorphous partially dehydrogenated boron carbide has been explored as a neutron voltaic for operation in radiation harsh environments, such as on deep space satellites/probes. A neutron voltaic device could also be used as a solid state neutron radiation detector to provide immediate alerts for radiation workers/students, as opposed to the passive dosimetry badges utilized today. Understanding how the irradiation environment effects the electrical properties of semiconducting amorphous partially dehydrogenated boron carbide is important to predicting the stability of these devices in operation. p-n heterojunction diodes were formed from the synthesis of semiconducting amorphous partially dehydrogenated boron carbide on silicon substrates through the use of plasma enhanced chemical vapor deposition (PECVD). Many forms of structural and electrical measurements and analysis have been performed on the p-n heterojunction devices as a function of both He+ ion and neutron irradiation including: transmission electron microscopy (TEM), selected area electron diffraction (SAED), current versus voltage I(V), capacitance versus voltage C(V), conductance versus frequency G(f), and charge carrier lifetime (tau). In stark contrast to nearly all other electronic devices, the electrical performance of these p-n heterojunction diodes improved with irradiation. This is most likely the result of bond defect passivation and resolution of degraded icosahedral based carborane structures (icosahedral molecules missing a B, C, or H atom(s)).

Making the Most of Waste Energy

NASA Technical Reports Server (NTRS)

2005-01-01

The Thermo-Mechanical Systems Branch at NASA s Glenn Research Center is responsible for planning and conducting research efforts to advance thermal systems for space, aerospace, and non-aerospace applications. Technological areas pertain to solar and thermal energy conversion. For example, thermo-mechanical systems researchers work with gas (Stirling) and liquid/vapor (Rankine) systems that convert thermal energy to electrical power, as well as solar dynamic power systems that concentrate sunlight to electrical power. The branch s development of new solar and thermal energy technologies is propelling NASA s missions deep into unfamiliar territories of space. Solar dynamic power systems are actively improving the health of orbiting satellites, giving them longer life and a stronger radiation tolerance, thus, creating less need for on-orbit maintenance. For future missions, NASA may probe even deeper into the mysterious cosmos, with the adoption of highly efficient thermal energy converters that have the potential to serve as the source of onboard electrical power for satellites and spacecraft. Research indicates that these thermal converters can deliver up to 5 times as much power as radioisotope thermoelectric generators in use today, for the same amount of radioisotope. On Earth, energy-converting technologies associated with NASA s Thermo-Mechanical Systems Branch are being used to recover and transform low-temperature waste heat into usable electric power, with a helping hand from NASA.

Electromagnetic sounding of the Earth's crust in the region of superdeep boreholes of Yamal-Nenets autonomous district using the fields of natural and controlled sources

NASA Astrophysics Data System (ADS)

Zhamaletdinov, A. A.; Petrishchev, M. S.; Shevtsov, A. N.; Kolobov, V. V.; Selivanov, V. N.; Barannik, M. B.; Tereshchenko, E. D.; Grigoriev, V. F.; Sergushin, P. A.; Kopytenko, E. A.; Biryulya, M. A.; Skorokhodov, A. A.; Esipko, O. A.; Damaskin, R. V.

2013-11-01

Electromagnetic soundings with the fields of natural (magnetotelluric (MT), and audio magnetotelluric (AMT)) and high-power controlled sources have been carried out in the region of the SG-6 (Tyumen) and SG-7 (En-Yakhin) superdeep boreholes in the Yamal-Nenets autonomous district (YaNAD). In the controlled-source soundings, the electromagnetic field was generated by the VL Urengoi-Pangody 220-kV industrial power transmission line (PTL), which has a length of 114 km, and ultralow-frequency (ULF) Zevs radiating antenna located at a distance of 2000 km from the signal recording sites. In the soundings with the Urengoi-Pangody PTL, the Energiya-2 generator capable of supplying up to 200 kW of power and Energiya-3 portable generator with a power of 2 kW were used as the sources. These generators were designed and manufactured at the Kola Science Center of the Russian Academy of Sciences. The soundings with the Energiya-2 generator were conducted in the frequency range from 0.38 to 175 Hz. The external generator was connected to the PTL in upon the agreement with the Yamal-Nenets Enterprise of Main Electric Networks, a branch of OAO FSK ES of Western Siberia. The connection was carried out by the wire-ground scheme during the routine maintenance of PTL in the nighttime. The highest-quality signals were recorded in the region of the SG-7 (En-Yakhin) superdeep borehole, where the industrial noise is lowest. The results of the inversion of the soundings with PTL and Zevs ULF transmitter completely agree with each other and with the data of electric logging. The MT-AMT data provide additional information about the deep structure of the region in the low-frequency range (below 1Hz). It is established that the section of SG-6 and SG-7 boreholes contains conductive layers in the depth intervals from 0.15 to 0.3 km and from 1 to 1.5 km. These layers are associated with the variations in the lithological composition, porosity, and fluid saturation of the rocks. The top of the poorly conductive Permian-Triassic complex is identified at a depth of about 7 km. On the basis of the MT data in the lowest frequency band (hourly and longer periods) with the observations at the Novosibirsk observatory taken into account, the distribution of electric resistivity up to a depth of 800 km is reconstructed. This distribution can be used as additional information when calculating the temperature and rheology of the lithosphere and upper mantle in West Siberia. The results of our studies demonstrate the high potential of the complex electromagnetic soundings with natural and controlled sources in the study of deep structure of the lithosphere and tracing deep oil-and-gas-bearing horizons in the sedimentary cover of the West Siberian Platform within the Yamal-Nenets autonomous district.

Passive safety device and internal short tested method for energy storage cells and systems

DOEpatents

Keyser, Matthew; Darcy, Eric; Long, Dirk; Pesaran, Ahmad

2015-09-22

A passive safety device for an energy storage cell for positioning between two electrically conductive layers of the energy storage cell. The safety device also comprising a separator and a non-conductive layer. A first electrically conductive material is provided on the non-conductive layer. A first opening is formed through the separator between the first electrically conductive material and one of the electrically conductive layers of the energy storage device. A second electrically conductive material is provided adjacent the first electrically conductive material on the non-conductive layer, wherein a space is formed on the non-conductive layer between the first and second electrically conductive materials. A second opening is formed through the non-conductive layer between the second electrically conductive material and another of the electrically conductive layers of the energy storage device. The first and second electrically conductive materials combine and exit at least partially through the first and second openings to connect the two electrically conductive layers of the energy storage device at a predetermined temperature.

Nano- and Microstructure Engineering: An Effective Method for Creating High Efficiency Magnesium Silicide Based Thermoelectrics.

PubMed

Farahi, Nader; Prabhudev, Sagar; Botton, Gianluigi A; Salvador, James R; Kleinke, Holger

2016-12-21

Considering the effect of CO 2 emission together with the depletion of fossil fuel resources on future generations, industries in particular the transportation sector are in deep need of a viable solution to follow the environmental regulation to limit the CO 2 emission. Thermoelectrics may be a practical choice for recovering the waste heat, provided their conversion energy can be improved. Here, the high temperature thermoelectric properties of high purity Bi doped Mg 2 (Si,Sn) are presented. The samples Mg 2 Si 1-x-y Sn x Bi y with x(Sn) ≥ 0.6 and y(Bi) ≥ 0.03 exhibited electrical conductivities and Seebeck coefficients of approximately 1000 Ω -1 cm -1 and -200 μV K -1 at 773 K, respectively, attributable to a combination of band convergence and microstructure engineering through ball mill processing. In addition to the high electrical conductivity and Seebeck coefficient, the thermal conductivity of the solid solutions reached values below 2.5 W m -1 K -1 due to highly efficient phonon scattering from mass fluctuation and grain boundary effects. These properties combined for zT values of 1.4 at 773 K with an average zT of 0.9 between 400 and 773 K. The transport properties were both highly reproducible across several measurement systems and were stable with thermal cycling.

Electrical engram: how deep brain stimulation affects memory.

PubMed

Lee, Hweeling; Fell, Jürgen; Axmacher, Nikolai

2013-11-01

Deep brain stimulation (DBS) is a surgical procedure involving implantation of a pacemaker that sends electric impulses to specific brain regions. DBS has been applied in patients with Parkinson's disease, depression, and obsessive-compulsive disorder (among others), and more recently in patients with Alzheimer's disease to improve memory functions. Current DBS approaches are based on the concept that high-frequency stimulation inhibits or excites specific brain regions. However, because DBS entails the application of repetitive electrical stimuli, it primarily exerts an effect on extracellular field-potential oscillations similar to those recorded with electroencephalography. Here, we suggest a new perspective on how DBS may ameliorate memory dysfunction: it may enhance normal electrophysiological patterns underlying long-term memory processes within the medial temporal lobe. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparison of the induced fields using different coil configurations during deep transcranial magnetic stimulation

PubMed Central

Ueno, Shoogo

2017-01-01

Stimulation of deeper brain structures by transcranial magnetic stimulation (TMS) plays a role in the study of reward and motivation mechanisms, which may be beneficial in the treatment of several neurological and psychiatric disorders. However, electric field distributions induced in the brain by deep transcranial magnetic stimulation (dTMS) are still unknown. In this paper, the double cone coil, H-coil and Halo-circular assembly (HCA) coil which have been proposed for dTMS have been numerically designed. The distributions of magnetic flux density, induced electric field in an anatomically based realistic head model by applying the dTMS coils were numerically calculated by the impedance method. Results were compared with that of standard figure-of-eight (Fo8) coil. Simulation results show that double cone, H- and HCA coils have significantly deep field penetration compared to the conventional Fo8 coil, at the expense of induced higher and wider spread electrical fields in superficial cortical regions. Double cone and HCA coils have better ability to stimulate deep brain subregions compared to that of the H-coil. In the mean time, both double cone and HCA coils increase risk for optical nerve excitation. Our results suggest although the dTMS coils offer new tool with potential for both research and clinical applications for psychiatric and neurological disorders associated with dysfunctions of deep brain regions, the selection of the most suitable coil settings for a specific clinical application should be based on a balanced evaluation between stimulation depth and focality. PMID:28586349

Characterization of deep level defects and thermally stimulated depolarization phenomena in La-doped TlInS{sub 2} layered semiconductor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seyidov, MirHasan Yu., E-mail: smirhasan@gyte.edu.tr; Suleymanov, Rauf A.; Mikailzade, Faik A.

2015-06-14

Lanthanum-doped high quality TlInS{sub 2} (TlInS{sub 2}:La) ferroelectric-semiconductor was characterized by photo-induced current transient spectroscopy (PICTS). Different impurity centers are resolved and identified. Analyses of the experimental data were performed in order to determine the characteristic parameters of the extrinsic and intrinsic defects. The energies and capturing cross section of deep traps were obtained by using the heating rate method. The observed changes in the Thermally Stimulated Depolarization Currents (TSDC) near the phase transition points in TlInS{sub 2}:La ferroelectric-semiconductor are interpreted as a result of self-polarization of the crystal due to the internal electric field caused by charged defects. Themore » TSDC spectra show the depolarization peaks, which are attributed to defects of dipolar origin. These peaks provide important information on the defect structure and localized energy states in TlInS{sub 2}:La. Thermal treatments of TlInS{sub 2}:La under an external electric field, which was applied at different temperatures, allowed us to identify a peak in TSDC which was originated from La-dopant. It was established that deep energy level trap BTE43, which are active at low temperature (T ≤ 156 K) and have activation energy 0.29 eV and the capture cross section 2.2 × 10{sup −14} cm{sup 2}, corresponds to the La dopant. According to the PICTS results, the deep level trap center B5 is activated in the temperature region of incommensurate (IC) phases of TlInS{sub 2}:La, having the giant static dielectric constant due to the structural disorders. From the PICTS simulation results for B5, native deep level trap having an activation energy of 0.3 eV and the capture cross section of 1.8 × 10{sup −16} cm{sup 2} were established. A substantial amount of residual space charges is trapped by the deep level localized energy states of B5 in IC-phase. While the external electric field is applied, permanent dipoles, which are originated from the charged B5 deep level defects, are aligned in the direction of the applied electric field and the equilibrium polarization can be reached in a relatively short time. When the polarization field is maintained, while cooling the temperature of sample to a sufficiently low degrees, the relaxation times of the aligned dipoles drastically increases. Practically, frozen internal electric field or electrets states remain inside the TlInS{sub 2}:La when the applied bias field is switched off. The influence of deep level defects on TSDC spectra of TlInS{sub 2}:La has been revealed for the first time.« less

Electromagnetic Measurements in an Active Oilfield Environment

NASA Astrophysics Data System (ADS)

Schramm, K. A.; Aldridge, D. F.; Bartel, L. C.; Knox, H. A.; Weiss, C. J.

2015-12-01

An important issue in oilfield development pertains to mapping and monitoring of the fracture distributions (either natural or man-made) controlling subsurface fluid flow. Although microseismic monitoring and analysis have been used for this purpose for several decades, there remain several ambiguities and uncertainties with this approach. We are investigating a novel electromagnetic (EM) technique for detecting and mapping hydraulic fractures in a petroleum reservoir by injecting an electrically conductive contrast agent into an open fracture. The fracture is subsequently illuminated by a strong EM field radiated by a large engineered antenna. Specifically, a grounded electric current source is applied directly to the steel casing of the borehole, either at/near the wellhead or at a deep downhole point. Transient multicomponent EM signals (both electric and magnetic) scattered by the conductivity contrast are then recorded by a surface receiver array. We are presently utilizing advanced 3D numerical modeling algorithms to accurately simulate fracture responses, both before and after insertion of the conductive contrast agent. Model results compare favorably with EM field data recently acquired in a Permian Basin oilfield. However, extraction of the very-low-amplitude fracture signatures from noisy data requires effective noise suppression strategies such as long stacking times, rejection of outliers, and careful treatment of natural magnetotelluric fields. Dealing with the ever-present "episodic EM noise" typical in an active oilfield environment (associated with drilling, pumping, machinery, traffic, etc.) constitutes an ongoing problem. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Downhole transmission system

DOEpatents

Hall, David R [Provo, UT; Fox, Joe [Spanish Fork, UT

2008-01-15

A transmission system in a downhole component comprises a data transmission element in both ends of the downhole component. Each data transmission element houses an electrically conducting coil in a MCEI circular trough. An electrical conductor connects both the transmission elements. The electrical conductor comprises at least three electrically conductive elements insulated from each other. In the preferred embodiment the electrical conductor comprises an electrically conducting outer shield, an electrically conducting inner shield and an electrical conducting core. In some embodiments of the present invention, the electrical conductor comprises an electrically insulating jacket. In other embodiments, the electrical conductor comprises a pair of twisted wires. In some embodiments, the electrical conductor comprises semi-conductive material.

Compendium of Single Event Effects Test Results for Commercial Off-The-Shelf and Standard Electronics for Low Earth Orbit and Deep Space Applications

NASA Technical Reports Server (NTRS)

Reddell, Brandon D.; Bailey, Charles R.; Nguyen, Kyson V.; O'Neill, Patrick M.; Wheeler, Scott; Gaza, Razvan; Cooper, Jaime; Kalb, Theodore; Patel, Chirag; Beach, Elden R.;

Electrical Grounding - a Field for Geophysicists and Electrical Engineers Partnership

NASA Astrophysics Data System (ADS)

Freire, P. F.; Pane, E.; Guaraldo, N.

2012-12-01

Technology for designing ground electrodes for high-voltage direct current transmission systems (HVDC) has being using in the last years, deep soil models based on a wide range of geophysical methods. These models shall include detailed representation of shallow soil, down to 100 meters, in order to allow the evaluation of the soil conditions where the ground electrodes will be buried. Also deep soil models are needed, to be used for the interference studies, which shall represent a soil volume of about 15 km deep and a surface area of about 15 to 30 km radius. Large facilities for power plants (hydroelectric and wind farms, for example) and industrial complexes (such as petrochemical plants) has become usual at the current stage of Brazil industrialization. Grounding mats for these facilities are made of a buried cooper mesh, interconnected to a wide variety of metallic masses, such as steel reinforced concrete foundations, ducts in general etc. These grounding systems may present dimensions with the order of hundreds of meters, and, at least in Brazil, are usually calculated by using electrical resistivity soil models, based on short spacing Wenner measurements (with maximum spacing of about 64 m.). The soil model shall be the best possible representation of the environment in which the grounding electrodes are immersed, for the purpose of calculation of resistance or for digital simulation. The model to be obtained is limited by the amount and quality of soil resistivity measurements are available, and the resources to be used in the calculations and simulations. Geophysics uses a wide range of technologies for exploring subsoil, ranging from surface measurements to wells logging - seismic, gravimetric, magnetic, electrical, electromagnetic and radiometric. The electrical and electromagnetic methods includes various measurement techniques (Wenner, Schlumberger, TDEM, Magneto-telluric etc.), which together allow the development of complex resistivity soil models, layered stratified or showing lateral variations, ranging down to several tens of kilometers deep, reaching the crust-mantle interface (typically with the order of 30-40 km). This work aims to analyze the constraints of the current soil models being used for grounding electrodes design, and suggests the need of a soil modeling methodology compatible with large grounding systems. Concerning the aspects related to soil modeling, electrical engineers need to get aware of geophysics resources, such as: - geophysical techniques for soil electrical resistivity prospection (down to about 15 kilometers deep); and - techniques for converting field measured data, from many different geophysical techniques, into adequate soil models for grounding grid simulation. It is also important to equalize the basic knowledge for the professionals that are working together for the specific purpose of soil modeling for electrical grounding studies. The authors have experienced the situation of electrical engineers working with geophysicists, but it was not clear for the latter the effective need of the electrical engineers, and for the engineers it was unknown the available geophysical resources, and also, what to do convert the large amount of soil resistivity data into a reliable soil model.

Physical properties of the Nankai inner accretionary prism sediments at Site C0002, IODP Expedition 348.

NASA Astrophysics Data System (ADS)

Kitamura, M.; Kitajima, H.; Henry, P.; Valdez, R. D., II; Josh, M.; Tobin, H. J.; Saffer, D. M.; Hirose, T.; Toczko, S.; Maeda, L.

2014-12-01

Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Expedition 348 focused on deepening the existing riser hole at Site C0002 to ~3000 meters below seafloor (mbsf) to access the deep interior of the Miocene inner accretionary prism. This unique tectonic environment, which has never before been sampled in situ by ocean drilling, was characterized through riser drilling, logging while drilling (LWD), mud gas monitoring and sampling, and cuttings and core analysis. Shipboard physical properties measurements including moisture and density (MAD), electrical conductivity, P-wave, natural gamma ray, and magnetic susceptibility measurements were performed mainly on cuttings samples from 870.5 to 3058.5 mbsf, but also on core samples from 2163 and 2204 mbsf. MAD measurements were conducted on seawater-washed cuttings ("bulk cuttings") in two size fractions of >4 mm and 1-4 mm from 870.5 to 3058.5 mbsf, and hand-picked intact cuttings from the >4 mm size fractions within 1222.5-3058.5 mbsf interval. The bulk cuttings show grain density of ~2.7 g/cm3, bulk density of 1.9 g/cm3 to 2.2 g/cm3, and porosity of 50% to 32%. Compared to the values on bulk cuttings, the intact cuttings show almost the same grain density, but higher bulk density and lower porosity, respectively. Combined with the MAD measurements on hand-picked intact cuttings and discrete core samples from previous expeditions, porosity generally decreases from ~60% to ~20% from the seafloor to 3000 mbsf at Site C0002. Electrical conductivity and P-wave velocity on discrete samples, which were prepared from both cuttings and core samples in the depth interval of 1745.5-3058.5 mbsf, range 0.15-0.9 S/m and 1.7-4.5 km/s, respectively. The electrical resistivity on discrete samples is higher than the LWD resistivity data but the overall depth trends are similar. The electrical conductivity and P-wave velocity on discrete samples corrected for in-situ pressure and temperature will be presented. The shipboard physical properties measurements on cuttings are very limited but can be useful with careful treatment and observation.

From chemolithoautotrophs to electrolithoautotrophs: CO2 fixation by Fe(II)-oxidizing bacteria coupled with direct uptake of electrons from solid electron sources.

PubMed

Ishii, Takumi; Kawaichi, Satoshi; Nakagawa, Hirotaka; Hashimoto, Kazuhito; Nakamura, Ryuhei

2015-01-01

At deep-sea vent systems, hydrothermal emissions rich in reductive chemicals replace solar energy as fuels to support microbial carbon assimilation. Until recently, all the microbial components at vent systems have been assumed to be fostered by the primary production of chemolithoautotrophs; however, both the laboratory and on-site studies demonstrated electrical current generation at vent systems and have suggested that a portion of microbial carbon assimilation is stimulated by the direct uptake of electrons from electrically conductive minerals. Here we show that chemolithoautotrophic Fe(II)-oxidizing bacterium, Acidithiobacillus ferrooxidans, switches the electron source for carbon assimilation from diffusible Fe(2+) ions to an electrode under the condition that electrical current is the only source of energy and electrons. Site-specific marking of a cytochrome aa3 complex (aa3 complex) and a cytochrome bc1 complex (bc1 complex) in viable cells demonstrated that the electrons taken directly from an electrode are used for O2 reduction via a down-hill pathway, which generates proton motive force that is used for pushing the electrons to NAD(+) through a bc1 complex. Activation of carbon dioxide fixation by a direct electron uptake was also confirmed by the clear potential dependency of cell growth. These results reveal a previously unknown bioenergetic versatility of Fe(II)-oxidizing bacteria to use solid electron sources and will help with understanding carbon assimilation of microbial components living in electronically conductive chimney habitats.

From chemolithoautotrophs to electrolithoautotrophs: CO2 fixation by Fe(II)-oxidizing bacteria coupled with direct uptake of electrons from solid electron sources

PubMed Central

Ishii, Takumi; Kawaichi, Satoshi; Nakagawa, Hirotaka; Hashimoto, Kazuhito; Nakamura, Ryuhei

2015-01-01

At deep-sea vent systems, hydrothermal emissions rich in reductive chemicals replace solar energy as fuels to support microbial carbon assimilation. Until recently, all the microbial components at vent systems have been assumed to be fostered by the primary production of chemolithoautotrophs; however, both the laboratory and on-site studies demonstrated electrical current generation at vent systems and have suggested that a portion of microbial carbon assimilation is stimulated by the direct uptake of electrons from electrically conductive minerals. Here we show that chemolithoautotrophic Fe(II)-oxidizing bacterium, Acidithiobacillus ferrooxidans, switches the electron source for carbon assimilation from diffusible Fe2+ ions to an electrode under the condition that electrical current is the only source of energy and electrons. Site-specific marking of a cytochrome aa3 complex (aa3 complex) and a cytochrome bc1 complex (bc1 complex) in viable cells demonstrated that the electrons taken directly from an electrode are used for O2 reduction via a down-hill pathway, which generates proton motive force that is used for pushing the electrons to NAD+ through a bc1 complex. Activation of carbon dioxide fixation by a direct electron uptake was also confirmed by the clear potential dependency of cell growth. These results reveal a previously unknown bioenergetic versatility of Fe(II)-oxidizing bacteria to use solid electron sources and will help with understanding carbon assimilation of microbial components living in electronically conductive chimney habitats. PMID:26500609

Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

DOE PAGES

Caselli, Niccolò; La China, Federico; Bao, Wei; ...

2015-06-05

Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magneticmore » intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. In conclusion, by exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.« less

In-Situ Wire Damage Detection System

NASA Technical Reports Server (NTRS)

Jolley, Scott T. (Inventor); Gibson, Tracy L. (Inventor); Medelius, Pedro J. (Inventor); Roberson, Luke B. (Inventor); Tate, Lanetra C. (Inventor); Smith, Trent M. (Inventor); Williams, Martha K. (Inventor)

2014-01-01

An in-situ system for detecting damage in an electrically conductive wire. The system includes a substrate at least partially covered by a layer of electrically conductive material forming a continuous or non-continuous electrically conductive layer connected to an electrical signal generator adapted to delivering electrical signals to the electrically conductive layer. Data is received and processed to identify damage to the substrate or electrically conductive layer. The electrically conductive material may include metalized carbon fibers, a thin metal coating, a conductive polymer, carbon nanotubes, metal nanoparticles or a combination thereof.

Assessing the authenticity of commercial deep-sea drinking water by chemical and isotopic approaches.

PubMed

Peng, Tsung-Ren; Liang, Wen-Jui; Liu, Tsang-Sen; Lin, Yu-Wen; Zhan, Wen-Jun

2015-01-01

This study combines stable isotopes and chemical elements with statistical principal component analysis (PCA) to assess the authenticity of bottled commercial drinking water desalinized from deep seawater in the Taiwan market. Isotopic results indicate that true bottled deep-sea drinking water (DSDW) exhibits about 0 ‰ for both δ(2)H and δ(18)O values, which are values similar to those of open seawater. By comparison, suspected counterfeit DSDW products display δ(2)H and δ(18)O values of around -51 ‰ and -8 ‰, respectively. These values are representative of terrestrial freshwater. In addition, suspected counterfeit DSDWs have δ and electrical conductivity values similar to a mixed water (MW) product that was manufactured by purifying terrestrial freshwater and adulterating this with small amounts of brine. Furthermore, PCA results indicate the chemical constitution of suspected DSDW products to be similar to the MW product which falls between purified terrestrial freshwater and desalinized open seawater. These similarities imply that suspected counterfeit DSDW products are manufactured in a similar manner to the declared MW product. This study demonstrates how combining knowledge of stable water isotopes and PCA can be used in assessing the authenticity of commercial DSDW products. The method should be of great interest to similar investigations elsewhere.

Monitoring hydraulic stimulation using telluric sounding

NASA Astrophysics Data System (ADS)

Rees, Nigel; Heinson, Graham; Conway, Dennis

2018-01-01

The telluric sounding (TS) method is introduced as a potential tool for monitoring hydraulic fracturing at depth. The advantage of this technique is that it requires only the measurement of electric fields, which are cheap and easy when compared with magnetotelluric measurements. Additionally, the transfer function between electric fields from two locations is essentially the identity matrix for a 1D Earth no matter what the vertical structure. Therefore, changes in the earth resulting from the introduction of conductive bodies underneath one of these sites can be associated with deviations away from the identity matrix, with static shift appearing as a galvanic multiplier at all periods. Singular value decomposition and eigenvalue analysis can reduce the complexity of the resulting telluric distortion matrix to simpler parameters that can be visualised in the form of Mohr circles. This technique would be useful in constraining the lateral extent of resistivity changes. We test the viability of utilising the TS method for monitoring on both a synthetic dataset and for a hydraulic stimulation of an enhanced geothermal system case study conducted in Paralana, South Australia. The synthetic data example shows small but consistent changes in the transfer functions associated with hydraulic stimulation, with grids of Mohr circles introduced as a useful diagnostic tool for visualising the extent of fluid movement. The Paralana electric field data were relatively noisy and affected by the dead band making the analysis of transfer functions difficult. However, changes in the order of 5% were observed from 5 s to longer periods. We conclude that deep monitoring using the TS method is marginal at depths in the order of 4 km and that in order to have meaningful interpretations, electric field data need to be of a high quality with low levels of site noise.[Figure not available: see fulltext.

3D Modeling of the Deep Groundwater System at Mount Shasta, California, Using Finite Difference and Inverse Modeling in Combination with Magnetotellurics

NASA Astrophysics Data System (ADS)

Webb, C. H.; Foglia, L.; Fogg, G. E.; McClain, J.

2017-12-01

Precipitation in mountainous systems is responsible for much of the world's freshwater supply. Volcanic mountains in particular may have the capacity to store large amounts of groundwater, due to the relatively high permeability of volcanic rocks as compared to fractured crystalline rocks. These qualities make volcanic aquifers likely candidates for laterally extensive deep groundwater systems. However, the depth extent of these aquifers is not well understood and has been little studied, due to the dearth of well data in most mountain systems. When determining a water budget, especially for mountainous regions, it is necessary to understand the extent of the entire system, including the deep components. Mount Shasta of the California cascade volcanoes is one potential case of a deep groundwater system with the capacity to store significant amounts of water. In order to develop a conceptual model of the role of deep and regional groundwater flow in the Mt. Shasta groundwater system, the region was modeled using MODFLOW_2005, the finite difference flow model developed by USGS. The model was constrained using SRTM topography data, spring flow rates, PRISM precipitation rates, and well log levels. Geologic cross sections and gravity data were referenced in order to create a realistic estimate of the aquifer's structure down to 6km in depth. The aquifer stratigraphy was then represented by using 6 layers with 2-4 zones of hydraulic conductivity per layer to account for both vertical and lateral differences in lithology as well as decreasing permeability with depth. These hydraulic conductivity parameters of the model were varied using inverse modeling (UCODE_2014) to determine which layers and zones could support flow and still produce results consistent with existing well logs. Depth of flow was also corroborated with resistivity data collected in Shasta Valley using magnetotelluric (MT) soundings. Depths with comparatively low electrical resistivity were assumed to be aquifer units, and zones with high resistivity were assumed to be aquitards. By performing MT soundings in multiple locations and dividing the model into zones, this model tests both the maximum depth of flow as well as how that depth varies with lithology and geographical location.

Conductivity Anomalies in Central Europe

NASA Astrophysics Data System (ADS)

Neska, Anne

2016-01-01

This paper is a review of studies which, by applying the magnetotelluric, geomagnetic deep sounding, and magnetovariational sounding methods (the latter refers to usage of the horizontal magnetic tensor), investigate Central Europe for zones of enhanced electrical conductivity. The study areas comprise the region of the Trans-European Suture Zone (i.e. the south Baltic region and Poland), the North German Basin, the German and Czech Variscides, the Pannonian Basin (Hungary), and the Polish, Slovakian, Ukrainian, and Romanian Carpathians. This part of the world is well investigated in terms of data coverage and of the density of published studies, whereas the certainty that the results lead to comprehensive interpretations varies within the reviewed literature. A comparison of spatially coincident or adjacent studies reveals the important role that the data coverage of a distinct conductivity anomaly plays for the consistency of results. The encountered conductivity anomalies are understood as linked to basin sediments, asthenospheric upwelling, large differences in lithospheric age, and—this concerns most of them, which all concentrate in the middle crust—tectonic boundaries that developed during all mountain building phases that have taken place on the continent.

The Wilkes subglacial basin eastern margin electrical conductivity anomaly

NASA Astrophysics Data System (ADS)

Rizzello, Daniele; Armadillo, Egidio; Ferraccioli, Fausto; Caneva, Giorgio

2014-05-01

We have analyzed the deep conductivity structure at the transition between the Transantarctic Mountains (TAM) and the eastern margin of the WSB in NVL, by means of the GDS (Geomagnetic Deep Sounding) technique, in order to constrain the geodynamical interpretation of this antarctic sector. The TAM form the uplifted flank of the Mesozoic and Cenozoic West Antarctic Rift System. Structure of the TAM rift flank has been partially investigated with different geophysical approaches.The Wilkes Subglacial Basin is a broad depression over 400 km wide at the George V Coast and 1200 km long. Geology, lithospheric structure and tectonics of the Basin are only partially known because the Basin is buried beneath the East Antarctic Ice Sheet and is located in a remote region which makes geophysical exploration logistically challenging. Different authors have proposed contrasting hypothesis regarding the origin of the WSB: it could represent a region of rifted continental crust, or it may have a flexural origin or might represent an "extended terrane". Recently aerogeophysical investigations have demonstrated a strong structural control on the margin. Magnetovariational studies carried out at high geomagnetic latitudes are often hampered by source effects, mainly due to the closeness to the Polar Electrojet currents systems (PEJ). Its presence, in fact, makes the uniform magnetic field assumption, on which the magnetovariational methods are based on, often invalid, which outcome is a bias in the GDS transfer functions and to compromise the reliability of the inverted models. Data from the aforementioned campaigns have been then processed under the ISEE project (Ice Sheet Electromagnetic Experiment), aimed at evaluate and mitigate the bias effect of the PEJ on geomagnetic an magnetotelluric transfer functions at high geomagnetic latitudes, by means of suitable processing algorithms, developed upon a statistical analysis study on PEJ effects (Rizzello et al. 2013). Recent results allowed for a new processing of a wide dataset acquired during three different international Antarctic campaigns supported by the Italian Antarctic Project: the BACKTAM, WIBEM and WISE expeditions. The qualitative analysis of the induction arrows, in the period range 20-170 s, reveals an approximately 2D regional electrical conductivity pattern with a clear differentiation between the three Terrains crossed by the GDS transect we have re-analized: the Robertson Bay, the Bowers and the Wilson Terrain. Bi-dimensional conductivity models, jointly with magnetic and gravimetric profiles, suggest a differentiation of the investigated area in three crustal sectors separated by the Daniels Range and the Bowers Mts., in close relation with main known structural lineaments; to the West, a deep conductivity anomaly is associated with the transition to the Wilkes Subglagial Basin. We deem that such anomaly, together with the magnetic and gravimetric signatures, is compatible with an extensional regime in the eastern margin of the WSB. References Rizzello, D., Armadillo, E., Manzella, A."Statistical analysis of the polar electrojet influence on geomagnetic transfer functions estimates, over wide time and space scales". EGU 2013 General Assembly, Wien - poster presentation.

Structural determinants of electric vehicle market growth : a National Center for Sustainable Transportation research report.

DOT National Transportation Integrated Search

2017-02-01

Zero emission vehicles (ZEV) and plug-in electric vehicles (PEV) are critical technologies to attain deep reductions in greenhouse gases from transportation. PEV markets, however, have grown more slowly than anticipated by many observers. In this stu...

Water and Electricity Do Mix: Studying Plates, Petroleum, and Permafrost using Marine Electromagnetism

NASA Astrophysics Data System (ADS)

Constable, S.

2015-12-01

Marine magnetotelluric (MT) and controlled-source electromagnetic (CSEM) sounding methods were developed in the early 1980's as deep-water academic tools to study the oceanic lithosphere and mantle. Electrical conductivity is a strong function of porosity, temperature, melting, and volatile content, and so marine MT and CSEM data can be used to address a variety of geological questions related to plate tectonics. These include the distribution of melt at mid-ocean ridges, the fate of fluids in subduction zones, and the nature of the lithosphere-asthenosphere boundary. With the advent of deepwater oil and gas drilling in the late 1990's, marine EM methods were embraced by the exploration community, and are now routinely used to assist in exploration and make drilling decisions for wells costing $100M or more. For countries without conventional hydrocarbon resources, gas hydrate offers the potential for energy production, and marine CSEM methods may be the only effective way to explore for and characterize this resource. The use of EM methods to map geothermal, groundwater, and mineral resources also has application in the marine environment. Water and electricity has proved to be a very successful mix!

Quantum confined Stark effects of single dopant in polarized hemispherical quantum dot: Two-dimensional finite difference approach and Ritz-Hassé variation method

NASA Astrophysics Data System (ADS)

El Harouny, El Hassan; Nakra Mohajer, Soukaina; Ibral, Asmaa; El Khamkhami, Jamal; Assaid, El Mahdi

2018-05-01

Eigenvalues equation of hydrogen-like off-center single donor impurity confined in polarized homogeneous hemispherical quantum dot deposited on a wetting layer, capped by insulated matrix and submitted to external uniform electric field is solved in the framework of the effective mass approximation. An infinitely deep potential is used to describe effects of quantum confinement due to conduction band offsets at surfaces where quantum dot and surrounding materials meet. Single donor ground state total and binding energies in presence of electric field are determined via two-dimensional finite difference approach and Ritz-Hassé variation principle. For the latter method, attractive coulomb correlation between electron and ionized single donor is taken into account in the expression of trial wave function. It appears that off-center single dopant binding energy, spatial extension and radial probability density are strongly dependent on hemisphere radius and single dopant position inside quantum dot. Influence of a uniform electric field is also investigated. It shows that Stark effect appears even for very small size dots and that single dopant energy shift is more significant when the single donor is near hemispherical surface.

Development of UItra-Low Temperature Motor Controllers: Ultra Low Temperatures Evaluation and Characterization of Semiconductor Technologies For The Next Generation Space Telescope

NASA Technical Reports Server (NTRS)

Elbuluk, Malik E.

2003-01-01

Electronics designed for low temperature operation will result in more efficient systems than room temperature. This improvement is a result of better electronic, electrical, and thermal properties of materials at low temperatures. In particular, the performance of certain semiconductor devices improves with decreasing temperature down to ultra-low temperature (-273 'C). The Low Temperature Electronics Program at the NASA Glenn Research Center focuses on research and development of electrical components and systems suitable for applications in deep space missions. Research is being conducted on devices and systems for use down to liquid helium temperatures (-273 'C). Some of the components that are being characterized include semiconductor switching devices, resistors, magnetics, and capacitors. The work performed this summer has focused on the evaluation of silicon-, silicon-germanium- and gallium-Arsenide-based (GaAs) bipolar, MOS and CMOS discrete components and integrated circuits (ICs), from room temperature (23 'C) down to ultra low temperatures (-263 'C).

Plasmonic metasurface cavity for simultaneous enhancement of optical electric and magnetic fields in deep subwavelength volume.

PubMed

Hong, Jongwoo; Kim, Sun-Je; Kim, Inki; Yun, Hansik; Mun, Sang-Eun; Rho, Junsuk; Lee, Byoungho

2018-05-14

It has been hard to achieve simultaneous plasmonic enhancement of nanoscale light-matter interactions in terms of both electric and magnetic manners with easily reproducible fabrication method and systematic theoretical design rule. In this paper, a novel concept of a flat nanofocusing device is proposed for simultaneously squeezing both electric and magnetic fields in deep-subwavelength volume (~λ 3 /538) in a large area. Based on the funneled unit cell structures and surface plasmon-assisted coherent interactions between them, the array of rectangular nanocavity connected to a tapered nanoantenna, plasmonic metasurface cavity, is constructed by periodic arrangement of the unit cell. The average enhancement factors of electric and magnetic field intensities reach about 60 and 22 in nanocavities, respectively. The proposed outstanding performance of the device is verified numerically and experimentally. We expect that this work would expand methodologies involving optical near-field manipulations in large areas and related potential applications including nanophotonic sensors, nonlinear responses, and quantum interactions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tooker, Angela C.; Felix, Sarah H.; Pannu, Satinderpall S.

A neural interface includes a first dielectric material having at least one first opening for a first electrical conducting material, a first electrical conducting material in the first opening, and at least one first interconnection trace electrical conducting material connected to the first electrical conducting material. A stiffening shank material is located adjacent the first dielectric material, the first electrical conducting material, and the first interconnection trace electrical conducting material.

Sb2O3/Ag/Sb2O3 Multilayer Transparent Conducting Films For Ultraviolet Organic Light-emitting Diode

NASA Astrophysics Data System (ADS)

Song, Chunyan; Zhang, Nan; Lin, Jie; Guo, Xiaoyang; Liu, Xingyuan

2017-01-01

A novel UV transparent conducting films based on Sb2O3/Ag/Sb2O3 (SAS) structure, which were prepared by an electron-beam thermal evaporation at room temperature. This SAS exhibits excellent electrical, optical and stable properties. Especially for UV region, the SAS has high transmittance of 80% at 306 nm and 92% at 335 nm, meanwhile achieving low sheet resistance ( ≤ 10 Ω sq-1). The UV OLED based on the SAS show competitive device performance. The UV OLED obtains the peak of UV electroluminescence at 376 nm and shows a very high maximum EQE of 4.1% with the maximum output power density of 5.18 mW cm-2. These results indicate that the potential of SAS applications in deep UV transparent electrodes and large-scale flexible transparent electronics.

Sb2O3/Ag/Sb2O3 Multilayer Transparent Conducting Films For Ultraviolet Organic Light-emitting Diode.

PubMed

Song, Chunyan; Zhang, Nan; Lin, Jie; Guo, Xiaoyang; Liu, Xingyuan

2017-01-25

A novel UV transparent conducting films based on Sb 2 O 3 /Ag/Sb 2 O 3 (SAS) structure, which were prepared by an electron-beam thermal evaporation at room temperature. This SAS exhibits excellent electrical, optical and stable properties. Especially for UV region, the SAS has high transmittance of 80% at 306 nm and 92% at 335 nm, meanwhile achieving low sheet resistance ( ≤ 10 Ω sq -1 ). The UV OLED based on the SAS show competitive device performance. The UV OLED obtains the peak of UV electroluminescence at 376 nm and shows a very high maximum EQE of 4.1% with the maximum output power density of 5.18 mW cm -2 . These results indicate that the potential of SAS applications in deep UV transparent electrodes and large-scale flexible transparent electronics.

Sb2O3/Ag/Sb2O3 Multilayer Transparent Conducting Films For Ultraviolet Organic Light-emitting Diode

PubMed Central

Song, Chunyan; Zhang, Nan; Lin, Jie; Guo, Xiaoyang; Liu, Xingyuan

2017-01-01

A novel UV transparent conducting films based on Sb2O3/Ag/Sb2O3 (SAS) structure, which were prepared by an electron-beam thermal evaporation at room temperature. This SAS exhibits excellent electrical, optical and stable properties. Especially for UV region, the SAS has high transmittance of 80% at 306 nm and 92% at 335 nm, meanwhile achieving low sheet resistance ( ≤ 10 Ω sq−1). The UV OLED based on the SAS show competitive device performance. The UV OLED obtains the peak of UV electroluminescence at 376 nm and shows a very high maximum EQE of 4.1% with the maximum output power density of 5.18 mW cm−2. These results indicate that the potential of SAS applications in deep UV transparent electrodes and large-scale flexible transparent electronics. PMID:28120888

Wide Bandgap Transparent Conducting Electrode of FTO/Ag/FTO Structure for Ultraviolet Light-Emitting Diodes.

PubMed

Yohn, Gyu-Jae; Jeong, Soae; Kang, Soo-Hyun; Kim, Si-Won; Noh, Beom-Rae; Oh, Semi; Jeong, Bong-Yong; Kim, Kyoung-Kook

2018-09-01

We investigated the effect of the Ag interlayer thickness on the structural, electrical and optical properties of FTO/Ag/FTO structures designed for use in wide bandgap transparent conducting electrodes. The top and bottom FTO layers were deposited on α-Al2O3 (0001) substrates via RF magnetron sputtering at 300 °C and Ag interlayers were deposited using an e-beam evaporator system. We optimized the figure of merit by changing the thickness of the inserted Ag interlayer from 10 nm to 14 nm, achieving a maximum value of 2.46 × 10-3 Ω-1 and a resistivity of 6.4 × 10-4 Ω · cm using an FTO (70 nm)/Ag (14 nm)/FTO (40 nm) structure. Furthermore, the average optical transmittance in the deep UV range (300 to 330 nm) was 82.8%.

Thermal Environmental Testing of NSTAR Engineering Model Ion Thrusters

NASA Technical Reports Server (NTRS)

Rawlin, Vincent K.; Patterson, Michael J.; Becker, Raymond A.

1999-01-01

NASA's New Millenium program will fly a xenon ion propulsion system on the Deep Space 1 Mission. Tests were conducted under NASA's Solar Electric Propulsion Technology Applications Readiness (NSTAR) Program with 3 different engineering model ion thrusters to determine thruster thermal characteristics over the NSTAR operating range in a variety of thermal environments. A liquid nitrogen-cooled shroud was used to cold-soak the thruster to -120 C. Initial tests were performed prior to a mature spacecraft design. Those results and the final, severe, requirements mandated by the spacecraft led to several changes to the basic thermal design. These changes were incorporated into a final design and tested over a wide range of environmental conditions.

Structure and vibrational properties of the dominant O-H center in β-Ga2O3

NASA Astrophysics Data System (ADS)

Weiser, Philip; Stavola, Michael; Fowler, W. Beall; Qin, Ying; Pearton, Stephen

2018-06-01

Hydrogen has a strong influence on the electrical properties of transparent conducting oxides where it can give rise to shallow donors and can passivate deep compensating defects. We have carried out infrared absorption experiments on H- and D-doped β-Ga2O3 that involve temperature- and polarization-dependent effects as well as relative H- and D-concentrations to probe the defect structures that hydrogen can form. The results of analysis of these data, coupled with detailed theoretical calculations, show that the dominant O-H vibrational line observed at 3437 cm-1 for hydrogenated Ga2O3 is due to a relaxed VGa-2H center.

Pathways of translation: deep brain stimulation.

PubMed

Gionfriddo, Michael R; Greenberg, Alexandra J; Wahegaonkar, Abhijeet L; Lee, Kendall H

2013-12-01

Electrical stimulation of the brain has a 2000 year history. Deep brain stimulation (DBS), one form of neurostimulation, is a functional neurosurgical approach in which a high-frequency electrical current stimulates targeted brain structures for therapeutic benefit. It is an effective treatment for certain neuropathologic movement disorders and an emerging therapy for psychiatric conditions and epilepsy. Its translational journey did not follow the typical bench-to-bedside path, but rather reversed the process. The shift from ancient and medieval folkloric remedy to accepted medical practice began with independent discoveries about electricity during the 19th century and was fostered by technological advances of the 20th. In this paper, we review that journey and discuss how the quest to expand its applications and improve outcomes is taking DBS from the bedside back to the bench. © 2013 Wiley Periodicals, Inc.

Evaluating sensitivity of complex electrical methods for monitoring CO2 intrusion into a shallow groundwater system and associated geochemical transformations

NASA Astrophysics Data System (ADS)

Dafflon, B.; Wu, Y.; Hubbard, S. S.; Birkholzer, J. T.; Daley, T. M.; Pugh, J. D.; Peterson, J.; Trautz, R. C.

2011-12-01

A risk factor of CO2 storage in deep geological formations includes its potential to leak into shallow formations and impact groundwater geochemistry and quality. In particular, CO2 decreases groundwater pH, which can potentially mobilize naturally occurring trace metals and ions commonly absorbed to or contained in sediments. Here, geophysical studies (primarily complex electrical method) are being carried out at both laboratory and field scales to evaluate the sensitivity of geophysical methods for monitoring dissolved CO2 distribution and geochemical transformations that may impact water quality. Our research is performed in association with a field test that is exploring the effects of dissolved CO2 intrusion on groundwater geochemistry. Laboratory experiments using site sediments (silica sand and some fraction of clay minerals) and groundwater were initially conducted under field relevant CO2 partial pressures (pCO2). A significant pH drop was observed with inline sensors with concurrent changes in fluid conductivity caused by CO2 dissolution. Electrical resistivity and electrical phase responses correlated well with the CO2 dissolution process at various pCO2. Specifically, resistivity decreased initially at low pCO2 condition resulting from CO2 dissolution followed by a slight rebound because of the transition of bicarbonate into non-dissociated carbonic acid at lower pH slightly reducing the total concentration of dissociated species. Continuous electrical phase decreases were also observed, which are interpreted to be driven by the decrease of surface charge density (due to the decrease of pH, which approaches the PZC of the sediments). In general, laboratory experiments revealed the sensitivity of electrical signals to CO2 intrusion into groundwater formations and can be used to guide field data interpretation. Cross well complex electrical data are currently being collected periodically throughout a field experiment involving the controlled release of dissolved CO2 into groundwater. The objective of the geophysical cross well monitoring effort is to evaluate the sensitivity of complex electrical methods to dissolved CO2 at the field scale. Here, we report on the ability to translate laboratory-based petrophysical information from lab to field scales, and on the potential of field complex electrical methods for remotely monitoring CO2-induced geochemical transformations.

Current oscillations in semi-insulating GaAs associated with field-enhanced capture of electrons by the major deep donor EL2

NASA Technical Reports Server (NTRS)

Kaminska, M.; Parsey, J. M.; Lagowski, J.; Gatos, H. C.

1982-01-01

Current oscillations thermally activated by the release of electrons from deep levels in undoped semiinsulating GaAs were observed for the first time. They were attributed to electric field-enhanced capture of electrons by the dominant deep donor EL2 (antisite AsGa defect). This enhanced capture is due to the configurational energy barrier of EL2, which is readily penetrated by hot electrons.

How localized acceptors limit p-type conductivity in GaN

NASA Astrophysics Data System (ADS)

Lyons, John L.

2013-03-01

Despite the impressive development of GaN as an optoelectronic material, p-type conductivity is still limited. Only a single acceptor impurity, magnesium, is known to lead to p-type GaN. But Mg is far from a well-behaved acceptor. Hydrogen is known to passivate Mg, necessitating a post-growth anneal for acceptor activation. In addition, the ionization energy is quite large (~ 200 meV in GaN), meaning only a few percent of Mg acceptors are ionized at room temperature. Thus, hole conductivity is limited, and high concentrations of Mg are required to achieve moderately p-type GaN. Other acceptor impurities have not proven to be effective p-type dopants, for reasons that are still unresolved. Using advanced first-principles calculations based on a hybrid functional, we investigate the electrical and optical properties of the isolated Mg acceptor and its complexes with hydrogen in GaN, InN, and AlN.[2] We employ a technique that overcomes the band-gap-problem of traditional density functional theory, and allows for quantitative predictions of acceptor ionization energies and optical transition energies. Our results allow us to explain the deep or shallow nature of the Mg acceptor and its relation to the optical signals observed in Mg-doped GaN. We also revisit the properties of other group-II acceptors in GaN. We find that all cation-site acceptors show behavior similar to MgGa, and lead to highly localized holes. The ZnGa and BeGa acceptors have ionization energies that are even larger than that of Mg, making them ineffective dopants. All acceptors cause large lattice distortions in their neutral charge state, in turn leading to deep, broad luminescence signals that can serve as a means of experimentally verifying the deep nature of these acceptors. This work was performed in collaboration with Audrius Alkauskas, Anderson Janotti, and Chris G. Van de Walle. It was supported by the NSF and by the Solid State Lighting and Energy Center at UCSB.

Apparatus for detecting alpha radiation in difficult access areas

DOEpatents

Steadman, Peter; MacArthur, Duncan W.

1997-09-02

An electrostatic alpha radiation detector for measuring alpha radiation emitted from inside an enclosure comprising an electrically conductive expandable electrode for insertion into the enclosure. After insertion, the electrically conductive expandable electrode is insulated from the enclosure and defines a decay cavity between the electrically conductive expandable electrode and the enclosure so that air ions generated in the decay cavity are electrostatically captured by the electrically conductive expandable electrode and the enclosure when an electric potential is applied between the electrically conductive expandable electrode and the enclosure. Indicator means are attached to the electrically conductive expandable electrode for indicating an electrical current produced by generation of the air ions generated in the decay cavity by collisions between air molecules and the alpha particles emitted from the enclosure. A voltage source is connected between the indicator means and the electrically conductive enclosure for creating an electric field between the electrically conductive expandable electrode and the enclosure.

Electrically driven deep ultraviolet MgZnO lasers at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suja, Mohammad; Bashar, Sunayna Binte; Debnath, Bishwajit

Semiconductor lasers in the deep ultraviolet (UV) range have numerous potential applications ranging from water purification and medical diagnosis to high-density data storage and flexible displays. Nevertheless, very little success was achieved in the realization of electrically driven deep UV semiconductor lasers to date. Here, we report the fabrication and characterization of deep UV MgZnO semiconductor lasers. These lasers are operated with continuous current mode at room temperature and the shortest wavelength reaches 284 nm. The wide bandgap MgZnO thin films with various Mg mole fractions were grown on c-sapphire substrate using radio-frequency plasma assisted molecular beam epitaxy. Metal-semiconductor-metal (MSM)more » random laser devices were fabricated using lithography and metallization processes. Besides the demonstration of scalable emission wavelength, very low threshold current densities of 29-33 A/cm 2 are achieved. Furthermore, numerical modeling reveals that impact ionization process is responsible for the generation of hole carriers in the MgZnO MSM devices. The interaction of electrons and holes leads to radiative excitonic recombination and subsequent coherent random lasing.« less

Electrically driven deep ultraviolet MgZnO lasers at room temperature

DOE PAGES

Suja, Mohammad; Bashar, Sunayna Binte; Debnath, Bishwajit; ...

2017-06-01

Semiconductor lasers in the deep ultraviolet (UV) range have numerous potential applications ranging from water purification and medical diagnosis to high-density data storage and flexible displays. Nevertheless, very little success was achieved in the realization of electrically driven deep UV semiconductor lasers to date. Here, we report the fabrication and characterization of deep UV MgZnO semiconductor lasers. These lasers are operated with continuous current mode at room temperature and the shortest wavelength reaches 284 nm. The wide bandgap MgZnO thin films with various Mg mole fractions were grown on c-sapphire substrate using radio-frequency plasma assisted molecular beam epitaxy. Metal-semiconductor-metal (MSM)more » random laser devices were fabricated using lithography and metallization processes. Besides the demonstration of scalable emission wavelength, very low threshold current densities of 29-33 A/cm 2 are achieved. Furthermore, numerical modeling reveals that impact ionization process is responsible for the generation of hole carriers in the MgZnO MSM devices. The interaction of electrons and holes leads to radiative excitonic recombination and subsequent coherent random lasing.« less

Qualification of Commercial XIPS(R) Ion Thrusters for NASA Deep Space Missions

NASA Technical Reports Server (NTRS)

Goebel, Dan M.; Polk, James E.; Wirz, Richard E.; Snyder, J.Steven; Mikellides, Ioannis G.; Katz, Ira; Anderson, John

2008-01-01

Electric propulsion systems based on commercial ion and Hall thrusters have the potential for significantly reducing the cost and schedule-risk of Ion Propulsion Systems (IPS) for deep space missions. The large fleet of geosynchronous communication satellites that use solar electric propulsion (SEP), which will approach 40 satellites by year-end, demonstrates the significant level of technical maturity and spaceflight heritage achieved by the commercial IPS systems. A program to delta-qualify XIPS(R) ion thrusters for deep space missions is underway at JPL. This program includes modeling of the thruster grid and cathode life, environmental testing of a 25-centimeter electromagnetic (EM) thruster over DAWN-like vibe and temperature profiles, and wear testing of the thruster cathodes to demonstrate the life and benchmark the model results. This paper will present the delta-qualification status of the XIPS thruster and discuss the life and reliability with respect to known failure mechanisms.

Persistent photocurrent and deep level traps in PLD-grown In-Ga-Zn-O thin films studied by thermally stimulated current spectroscopy

NASA Astrophysics Data System (ADS)

Wang, Buguo; Anders, Jason; Leedy, Kevin; Schuette, Michael; Look, David

2018-02-01

InGaZnO (IGZO) is a promising semiconductor material for thin-film transistors (TFTs) used in DC and RF switching applications, especially since it can be grown at low temperatures on a wide variety of substrates. Enhancement-mode TFTs based on IGZO thin films grown by pulsed laser deposition (PLD) have been recently fabricated and these transistors show excellent performance; however, compositional variations and defects can adversely affect film quality, especially in regard to electrical properties. In this study, we use thermally stimulated current (TSC) spectroscopy to characterize the electrical properties and the deep traps in PLD-grown IGZO thin films. It was found that the as-grown sample has a DC activation energy of 0.62 eV, and two major traps with activation energies at 0.16-0.26 eV and at 0.90 eV. However, a strong persistent photocurrent (PPC) sometimes exists in the as-grown sample, so we carry out post-growth annealing in an attempt to mitigate the effect. It was found that annealing in argon increases the conduction, produces more PPC and also makes more traps observable. Annealing in air makes the film more resistive, and removes PPC and all traps but one. This work demonstrates that current-based trap emission, such as that associated with the TSC, can effectively reveal electronic defects in highlyresistive semiconductor materials, especially those are not amenable to capacitance-based techniques, such as deeplevel transient spectroscopy (DLTS).

A foldable electrode array for 3D recording of deep-seated abnormal brain cavities

NASA Astrophysics Data System (ADS)

Kil, Dries; De Vloo, Philippe; Fierens, Guy; Ceyssens, Frederik; Hunyadi, Borbála; Bertrand, Alexander; Nuttin, Bart; Puers, Robert

2018-06-01

Objective. This study describes the design and microfabrication of a foldable thin-film neural implant and investigates its suitability for electrical recording of deep-lying brain cavity walls. Approach. A new type of foldable neural electrode array is presented, which can be inserted through a cannula. The microfabricated electrode is specifically designed for electrical recording of the cavity wall of thalamic lesions resulting from stroke. The proof-of-concept is demonstrated by measurements in rat brain cavities. On implantation, the electrode array unfolds in the brain cavity, contacting the cavity walls and allowing recording at multiple anatomical locations. A three-layer microfabrication process based on UV-lithography and Reactive Ion Etching is described. Electrochemical characterization of the electrode is performed in addition to an in vivo experiment in which the implantation procedure and the unfolding of the electrode are tested and visualized. Main results. Electrochemical characterization validated the suitability of the electrode for in vivo use. CT imaging confirmed the unfolding of the electrode in the brain cavity and analysis of recorded local field potentials showed the ability to record neural signals of biological origin. Significance. The conducted research confirms that it is possible to record neural activity from the inside wall of brain cavities at various anatomical locations after a single implantation procedure. This opens up possibilities towards research of abnormal brain cavities and the clinical conditions associated with them, such as central post-stroke pain.

Low resistance thin film organic solar cell electrodes

DOEpatents

Forrest, Stephen [Princeton, NJ; Xue, Jiangeng [Piscataway, NJ

2008-01-01

A method which lower the series resistance of photosensitive devices includes providing a transparent film of a first electrically conductive material arranged on a transparent substrate; depositing and patterning a mask over the first electrically conductive material, such that openings in the mask have sloping sides which narrow approaching the substrate; depositing a second electrically conductive material directly onto the first electrically conductive material exposed in the openings of the mask, at least partially filling the openings; stripping the mask, leaving behind reentrant structures of the second electrically conductive material which were formed by the deposits in the openings of the mask; after stripping the mask, depositing a first organic material onto the first electrically conductive material in between the reentrant structures; and directionally depositing a third electrically conductive material over the first organic material deposited in between the reentrant structures, edges of the reentrant structures aligning deposition so that the third electrically conductive material does not directly contact the first electrically conductive material, and does not directly contact the second electrically conductive material.

New Opportunities for Outer Solar System Science using Radioisotope Electric Propulsion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noble, Robert J.; /SLAC; Amini, Rashied

Today, our questions and hypotheses about the Solar System's origin have surpassed our ability to deliver scientific instruments to deep space. The moons of the outer planets, the Trojan and Centaur minor planets, the trans-Neptunian objects (TNO), and distant Kuiper Belt objects (KBO) hold a wealth of information about the primordial conditions that led to the formation of our Solar System. Robotic missions to these objects are needed to make the discoveries, but the lack of deep-space propulsion is impeding this science. Radioisotope electric propulsion (REP) will revolutionize the way we do deep-space planetary science with robotic vehicles, giving themmore » unprecedented mobility. Radioisotope electric generators and lightweight ion thrusters are being developed today which will make possible REP systems with specific power in the range of 5 to 10 W/kg. Studies have shown that this specific power range is sufficient to perform fast rendezvous missions from Earth to the outer Solar System and fast sample return missions. This whitepaper discusses how mobility provided by REP opens up entirely new science opportunities for robotic missions to distant primitive bodies. We also give an overview of REP technology developments and the required next steps to realize REP.« less

Flexible neural interfaces with integrated stiffening shank

DOEpatents

Tooker, Angela C.; Felix, Sarah H.; Pannu, Satinderpall S.; Shah, Kedar G.; Sheth, Heeral; Tolosa, Vanessa

2016-07-26

A neural interface includes a first dielectric material having at least one first opening for a first electrical conducting material, a first electrical conducting material in the first opening, and at least one first interconnection trace electrical conducting material connected to the first electrical conducting material. A stiffening shank material is located adjacent the first dielectric material, the first electrical conducting material, and the first interconnection trace electrical conducting material.

Deep electrical investigations in the Long Valley geothermal area, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stanley, W.D.; Jackson, D.B.; Zohdy, A.A.R.

1976-02-10

Direct current resistivity and time domain electromagnetic techniques were used to study the electrical structure of the Long Valley geothermal area. A resistivity map was compiled from 375 total field resistivity measurements. Two significant zones of low resistivity were detected, one near Casa Diablo Hot Springs and one surrounding the Cashbaugh Ranch-Whitmore Hot Springs area. These anomalies and other parts of the caldera were investigated in detail with 49 Schlumberger dc soundings and 13 transient electromagnetic soundings. An extensive conductive zone of 1- to 10-..cap omega..m resistivity was found to be the cause of the total field resistivity lows. Drillmore » hole information indicates that the shallow parts of the conductive zone in the eastern part of the caldera contain water of only 73/sup 0/C and consist of highly zeolitized tuffs and ashes in the places that were tested. A deeper zone near Whitmore Hot Springs is somewhat more promising in potential for hot water, but owing to the extensive alteration prevalent in the caldera the presence of hot water cannot be definitely assumed. The resistivity results indicate that most of the past hydrothermal activity, and probably most of the present activity, is controlled by fracture systems related to regional Sierran faulting.« less

The Influence of High-Power Ion Beams and High-Intensity Short-Pulse Implantation of Ions on the Properties of Ceramic Silicon Carbide

NASA Astrophysics Data System (ADS)

Kabyshev, A. V.; Konusov, F. V.; Pavlov, S. K.; Remnev, G. E.

2016-02-01

The paper is focused on the study of the structural, electrical and optical characteristics of the ceramic silicon carbide before and after irradiation in the regimes of the high-power ion beams (HPIB) and high-intensity short-pulse implantation (HISPI) of carbon ions. The dominant mechanism of transport of charge carriers, their type and the energy spectrum of localized states (LS) of defects determining the properties of SiC were established. Electrical and optical characteristics of ceramic before and after irradiation are determined by the biographical and radiation defects whose band gap (BG) energy levels have a continuous energetic distribution. A dominant p-type activation component of conduction with participation of shallow acceptor levels 0.05-0.16 eV is complemented by hopping mechanism of conduction involving the defects LS with a density of 1.2T017-2.4T018 eV-Am-3 distributed near the Fermi level.The effect of radiation defects with deep levels in the BG on properties change dominates after HISPI. A new material with the changed electronic structure and properties is formed in the near surface layer of SiC after the impact of the HPIB.

[The pedunculopontine nucleus. A structure involved in motor and emotional processing].

PubMed

Blanco-Lezcano, L; Pavón-Fuentes, N; Serrano-Sánchez, T; Blanco-Lezcano, V; Coro-Grave de Peralta, Y; Joseph-Bouza, Y

There is currently a growing interest for conducting studies into the electrical and neurochemical activity of the pedunculopontine nucleus (PPN) due to the privileged position occupied by this structure in the flow of information to and from the cortex. This nucleus acts as a relay, not only for the motor information that is processed in the basal ganglia but also for information of an emotional type, whose main centre is the nucleus accumbens. It is also strongly linked with the aspects that determine the mechanisms governing addiction to certain drugs. We conduct a detailed analysis of the main findings from studies of the role played by the PPN in the physiopathology of Parkinsonism, namely the study of metabolic activity, immunohistochemical studies with different tracers, electrophysiological studies that have confirmed the immunohistochemical observations, as well as deep electrical stimulation carried out in non human primates. Furthermore, we also examine the part played by this structure in the processing of emotional information associated with different learning tasks. Overall, the authors grant the PPN a privileged position in the physiopathology of the axial disorders related to Parkinson s disease; its most important afference, stemming from the subthalamic nucleus, appears to play a key role in the understanding of the part played by the PPN in Parkinsonism.

CHARACTERISTICS OF RANGE HOODS IN CALIFORNIA HOMES DATA COLLECTED FROM A REAL ESTATE WEB SITE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klug, Victoria; Singer, Brett; Bedrosian, Tod

2011-09-02

Venting range hoods are important residential ventilation components that remove pollutants generated by cooking activities and natural gas cooking burners. To address the lack of data on range hood installations in California, we conducted a survey by examining photographs of homes for sale or rent listed on a popular real estate web site. The survey was conducted in November 2010 and April–May 2011. Posted photos of the homes were reviewed to determine if a hood was installed, the type of hood, and two installation details that can impact performance, namely the height above the cooktop and the degree to whichmore » the hood covers the cooktop burners. We additionally collected information about the homes, including asking price for purchase or rent, type of building (e.g. detached house, townhouse or apartment), building age, floor area, and cooktop fuel type. Listings were first sampled to focus on homes built since 2005, then randomly sampled to include varied prices and locations around the state. Data were obtained for 1002 homes built between 1865 and 2011 (median year built 1989). Homes for sale varied in asking price from $16,000 to $16,500,000 (median $353,000) and homes for rent varied from $500 to $25,000 (median $2125) per month. Approximately 74% of the sample had natural gas cooktops. In this sample, natural gas cooktops were more prevalent in more expensive homes than in less expensive homes. Across the entire sample, 7.4 % appeared to have no hood installed, 33% had a short hood, 13% had a deep hood and 47% had a microwave over the range. The percentage of these hoods that vent to the outdoors could not be determined. Hood type was related to coverage of the cooktop. For deep hoods, 76% appeared to cover most or all of the cooktop burners. For short hoods, 70% covered about three quarters of the cooktop. And for microwaves the vast majority (96%) covered the back burners but not the front burners. Hood type was also correlated with asking price or monthly rent, with deep hoods most common in the most expensive homes. Hood type was also correlated with home age, with microwave hoods more common in newer homes. Installation height was related to device type with microwaves installed lower (closer) to the cooktop (median 18 inches), and short hoods (median 28 inches) and deep hoods (median 30 inches) installed higher. Deep range hoods are more common with natural gas cooktops than with electric cooktops, and slightly fewer homes with natural gas cooktops lack a range hood (7%) than homes with electric cooktops (9%). This study provides limited but useful information about the characteristics of range hoods in California homes and demonstrates the potential value of non-traditional forms of data collection.« less

Induced conductivity in sol-gel ZnO films by passivation or elimination of Zn vacancies

NASA Astrophysics Data System (ADS)

Winarski, D. J.; Anwand, W.; Wagner, A.; Saadatkia, P.; Selim, F. A.; Allen, M.; Wenner, B.; Leedy, K.; Allen, J.; Tetlak, S.; Look, D. C.

2016-09-01

Undoped and Ga- and Al- doped ZnO films were synthesized using sol-gel and spin coating methods and characterized by X-ray diffraction, high-resolution scanning electron microscopy (SEM), optical spectroscopy and Hall-effect measurements. SEM measurements reveal an average grain size of 20 nm and distinct individual layer structure. Measurable conductivity was not detected in the unprocessed films; however, annealing in hydrogen or zinc environment induced significant conductivity (˜10-2 Ω .cm) in most films. Positron annihilation spectroscopy measurements provided strong evidence that the significant enhancement in conductivity was due to hydrogen passivation of Zn vacancy related defects or elimination of Zn vacancies by Zn interstitials which suppress their role as deep acceptors. Hydrogen passivation of cation vacancies is shown to play an important role in tuning the electrical conductivity of ZnO, similar to its role in passivation of defects at the Si/SiO2 interface that has been essential for the successful development of complementary metal-oxide-semiconductor (CMOS) devices. By comparison with hydrogen effect on other oxides, we suggest that hydrogen may play a universal role in oxides passivating cation vacancies and modifying their electronic properties.

A Simulation Based Investigation of High Latency Space Systems Operations

NASA Technical Reports Server (NTRS)

Li, Zu Qun; Moore, Michael; Bielski, Paul; Crues, Edwin Z.

2017-01-01

This study was the first in a series of planned tests to use physics-based subsystem simulations to investigate the interactions between a spacecraft's crew and a ground-based mission control center for vehicle subsystem operations across long communication delays. The simulation models the life support system of a deep space habitat. It contains models of an environmental control and life support system, an electrical power system, an active thermal control systems, and crew metabolic functions. The simulation has three interfaces: 1) a real-time crew interface that can be use to monitor and control the subsystems; 2) a mission control center interface with data transport delays up to 15 minute each way; and 3) a real-time simulation test conductor interface used to insert subsystem malfunctions and observe the interactions between the crew, ground, and simulated vehicle. The study was conducted at the 21st NASA Extreme Environment Mission Operations (NEEMO) mission. The NEEMO crew and ground support team performed a number of relevant deep space mission scenarios that included both nominal activities and activities with system malfunctions. While this initial test sequence was focused on test infrastructure and procedures development, the data collected in the study already indicate that long communication delays have notable impacts on the operation of deep space systems. For future human missions beyond cis-lunar, NASA will need to design systems and support tools to meet these challenges. These will be used to train the crew to handle critical malfunctions on their own, to predict malfunctions and assist with vehicle operations. Subsequent more detailed and involved studies will be conducted to continue advancing NASA's understanding of space systems operations across long communications delays.

A Simulation Based Investigation of High Latency Space Systems Operations

NASA Technical Reports Server (NTRS)

Li, Zu Qun; Crues, Edwin Z.; Bielski, Paul; Moore, Michael

2017-01-01

This study was the first in a series of planned tests to use physics-based subsystem simulations to investigate the interactions between a spacecraft's crew and a ground-based mission control center for vehicle subsystem operations across long communication delays. The simulation models the life support system of a deep space habitat. It contains models of an environmental control and life support system, an electrical power system, an active thermal control system, and crew metabolic functions. The simulation has three interfaces: 1) a real-time crew interface that can be use to monitor and control the subsystems; 2) a mission control center interface with data transport delays up to 15 minute each way; and 3) a real-time simulation test conductor interface used to insert subsystem malfunctions and observe the interactions between the crew, ground, and simulated vehicle. The study was conducted at the 21st NASA Extreme Environment Mission Operations (NEEMO) mission. The NEEMO crew and ground support team performed a number of relevant deep space mission scenarios that included both nominal activities and activities with system malfunctions. While this initial test sequence was focused on test infrastructure and procedures development, the data collected in the study already indicate that long communication delays have notable impacts on the operation of deep space systems. For future human missions beyond cis-lunar, NASA will need to design systems and support tools to meet these challenges. These will be used to train the crew to handle critical malfunctions on their own, to predict malfunctions, and to assist with vehicle operations. Subsequent more detailed and involved studies will be conducted to continue advancing NASA's understanding of space systems operations across long communications delays.

Mobile geophysical study of peat deposits in Fuhrberger Field, Germany

NASA Astrophysics Data System (ADS)

Wunderlich, T.; Petersen, H.; Hagrey, S. A. al; Rabbel, W.

2012-04-01

In the water protection area of Fuhrberger Field, north of Hanover, geophysical techniques were applied to study the stakeholder problem of the source detection for nitrate accumulations in the ground water. We used our mobile multisensor platform to conduct measurements using Ground Penetrating Radar (GPR, 200 MHz antenna) and Electromagnetic Induction (EMI, EM31). This aims to study the subsurface occurrences of peat deposits (surplus of organic carbon) supposed to be a source of nitrate emissions due to the aeration and the drawdown of groundwater levels (e.g. by pumping, drainage etc.). Resulting EMI and GPR signals show high data quality. Measured apparent electrical conductivity shows very low values (<10 mS/m) due to the mainly sandy subsurface. For this medium, both methods are expected to penetrate down to 3-5 m depth. GPR radargrams, time slices of GPR reflection energy and EMI apparent electrical conductivities are plotted on aerial photographs and compared to each other's and with vegetation intensity. We could separate areas characterized by low reflection energy and high conductivity, and vice versa. Briefly, organic rich sediments such as peats are assumed to have a relative high conductivity and thus low GPR reflectivity. Some areas of local conductivity increase correspond to a deep reflection interface (as seen in the radargrams), which even vanishes due to the high attenuation caused by the high conductivity. This implies that the upper layer is more conductive than the lower layer. Several local areas with these characteristics are found at the study sites. We recommend shallow drillings at representative points to deliver the necessary confirmation with ground truth information. Acknowledgments: iSOIL (Interactions between soil related sciences - Linking geophysics, soil science and digital soil mapping) is a Collaborative Project (Grant Agreement number 211386) co-funded by the Research DG of the European Commission within the RTD activities of the FP7 Thematic Priority Environment.

Apparatus for detecting alpha radiation in difficult access areas

DOEpatents

Steadman, P.; MacArthur, D.W.

1997-09-02

An electrostatic alpha radiation detector for measuring alpha radiation emitted from inside an enclosure comprising an electrically conductive expandable electrode for insertion into the enclosure is disclosed. After insertion, the electrically conductive expandable electrode is insulated from the enclosure and defines a decay cavity between the electrically conductive expandable electrode and the enclosure so that air ions generated in the decay cavity are electrostatically captured by the electrically conductive expandable electrode and the enclosure when an electric potential is applied between the electrically conductive expandable electrode and the enclosure. Indicator means are attached to the electrically conductive expandable electrode for indicating an electrical current produced by generation of the air ions generated in the decay cavity by collisions between air molecules and the alpha particles emitted from the enclosure. A voltage source is connected between the indicator means and the electrically conductive enclosure for creating an electric field between the electrically conductive expandable electrode and the enclosure. 4 figs.

Field-Assisted Splitting of Pure Water Based on Deep-Sub-Debye-Length Nanogap Electrochemical Cells.

PubMed

Wang, Yifei; Narayanan, S R; Wu, Wei

2017-08-22

Owing to the low conductivity of pure water, using an electrolyte is common for achieving efficient water electrolysis. In this paper, we have fundamentally broken through this common sense by using deep-sub-Debye-length nanogap electrochemical cells to achieve efficient electrolysis of pure water (without any added electrolyte) at room temperature. A field-assisted effect resulted from overlapped electrical double layers can greatly enhance water molecules ionization and mass transport, leading to electron-transfer limited reactions. We have named this process "virtual breakdown mechanism" (which is completely different from traditional mechanisms) that couples the two half-reactions together, greatly reducing the energy losses arising from ion transport. This fundamental discovery has been theoretically discussed in this paper and experimentally demonstrated in a group of electrochemical cells with nanogaps between two electrodes down to 37 nm. On the basis of our nanogap electrochemical cells, the electrolysis current density from pure water can be significantly larger than that from 1 mol/L sodium hydroxide solution, indicating the much better performance of pure water splitting as a potential for on-demand clean hydrogen production.

Photo-electrical and transport properties of hydrothermal ZnO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onufrijevs, P., E-mail: onufrijevs@latnet.lv; Medvid, A.; Ščajev, P.

2016-04-07

We performed the studies of optical, photoelectric, and transport properties of a hydrothermal bulk n-type ZnO crystal by using the contactless optical techniques: photoluminescence, light-induced transient grating, and differential reflectivity. Optical studies revealed bound exciton and defect-related transitions between the donor states (at ∼60 meV and ∼240 meV below the conduction band) and the deep acceptor states (at 0.52 eV above the valence band). The acceptor state was ascribed to V{sub Zn}, and its thermal activation energy of 0.43 eV was determined. A low value of carrier diffusion coefficient (∼0.1 cm{sup 2}/s) at low excitations and temperatures up to 800 K was attributed to impact themore » recharged deep acceptors. Electron and hole mobilities of 140 and ∼80 cm{sup 2}/Vs, correspondently, were determined at room temperature. The decrease of carrier lifetime with excitation was ascribed to increasing rate of radiative recombination at low temperatures and nonradiative recombination above the room temperature.« less

Triple Halo Coil: Development and Comparison with Other TMS Coils

NASA Astrophysics Data System (ADS)

Rastogi, Priyam; Hadimani, Ravi; Jiles, David

Transcranial Magnetic Stimulation (TMS) is a non-invasive stimulation technique that can be used for the treatment of various neurological disorders such as Parkinson's Disease, PTSD, TBI and anxiety by regulating synaptic activity. TMS is FDA approved for the treatment of major depressive disorder. There is a critical need to develop deep TMS coils that can stimulate deeper regions of the brain without excessively stimulating the cortex in order to provide an alternative to surgical methods. We have developed a novel multi-coil configuration called ``Triple Halo Coil'' (THC) that can stimulate deep brain regions. Investigation of induced electric and magnetic field in these regions have been achieved by computer modelling. Comparison of the results due to THC configuration have been conducted with other TMS coils such as ``Halo Coil'', circular coil and ``Figure of Eight'' coil. There was an improvement of more than 15 times in the strength of magnetic field, induced by THC configuration at 10 cm below the vertex of the head when compared with the ``Figure of Eight'' coil alone. Carver Charitable Trust.

Dielectric Breakdown Weathering by Solar Energetic Particles Charging Airless Bodies in the Inner Solar System

NASA Astrophysics Data System (ADS)

Jordan, A.; Stubbs, T. J.; Wilson, J. K.; Schwadron, N.; Spence, H. E.; Hayne, P. O.; Izenberg, N.

2016-12-01

Solar energetic particles (SEPs) can penetrate regoliths of airless bodies to depths of 1 mm and cause deep dielectric charging. This charging is predicted to dissipate slowly (on the order of days) in regoliths with low electrical conductivities, which could form subsurface electric fields (> 106 V/m) large enough to cause dielectric breakdown (or "sparking"). Colder regoliths are expected to have lower conductivities, so the coldest regions of airless planetary bodies can become the most deep dielectrically charged. Consequently, large SEP events may cause dielectric breakdown in these regions, possibly contributing to space weathering on airless bodies in the inner solar system. Previous work has predicted that, in permanently shadowed regions (PSRs) on the Moon, breakdown weathering may have melted and/or vaporized 10-25 wt% of the meteoritically gardened regolith, a percentage comparable to weathering by meteoroid impacts. But much of the Moon's nightside can also reach cold (<100 K) temperatures, so we now show how breakdown weathering may have affected 4-11 wt% of the gardened regolith over the entire lunar surface. We use data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO) to show two examples of SEP events that may have caused breakdown on the Moon. We also scale large SEP events to the orbit of Mars and predict the rate at which they may cause dielectric breakdown on Phobos and Deimos, whose polar regions remain <100 K during their long winters (nearly half an Earth year). On these satellites, the gardening rates are unknown, so we estimate the percentage of regolith affected in these locations as a function of gardening rate. Finally, we briefly show that dielectric breakdown may occur on asteroids that have either high obliquities or PSRs, like Vesta and Ceres, respectively. This work also emphasizes the need for laboratory experiments to inform both remote sensing observations and the analysis of samples already obtained during the Luna and Apollo missions.

[The role of magnetic stimulation in diagnosis of the peripheral nervous system].

PubMed

Dressler, D; Benecke, R; Meyer, B U; Conrad, B

1988-12-01

Magnetic stimulation has recently been introduced as a new method for stimulation of neuronal tissues. Up to now most investigators were emphasized the advantages of this method for the investigation of the central nervous system. With this paper we want to show that magnetic stimulation may also be useful for the examination of the peripheral nervous system. Both, magnetic and electrical stimulation, seem to employ the same stimulation mechanisms in the nervous tissue. The results obtained with both methods should therefore be comparable. By measuring EMG-latencies after electrical and magnetic stimulation (Fig. 1) the exact site of magnetic stimulation can be determined. Magnetic stimulation offers major advantages over electrical stimulation: 1) Magnetic stimulation is a painless method even when high stimulus intensities are used. 2) Magnetic stimulation can reach deep neuronal structures that are not easily accessible using electrical stimulation (Fig. 2, Fig. 3). 3) Using a wide range of stimulus intensities (Fig. 4, Fig. 5) magnetic stimulation provides a much better descrimination of different components of the compound muscle action potential than electrical stimulation. Magnetic stimulation seems to be a promising new method for the electrodiagnostic examination of pain- sensitive patients, especially when deep-lying peripheral nerves have to be investigated.

3D soil water nowcasting using electromagnetic conductivity imaging and the ensemble Kalman filter

NASA Astrophysics Data System (ADS)

Huang, Jingyi; McBratney, Alex; Minasny, Budiman; Triantafilis, John

2017-04-01

Mapping and immediate forecasting of soil water content (θ) and its movement can be challenging. Although apparent electrical conductivity (ECa) measured by electromagnetic induction has been used, it is difficult to apply it along a transect or across a field. Across a 3.95-ha field with varying soil texture, an ensemble Kalman filter (EnFK) was used to monitor and nowcast θ dynamics in 2-d and 3-d over 16 days. The EnKF combined a physical model fitted with θ measured by soil moisture sensors and an Artificial Neural Network model comprising estimate of true electrical conductivity (σ) generated by inversions of DUALEM-421S ECa data. Results showed that the spatio-temporal variation in θ can be successfully modelled using the EnKF (Lin's concordance = 0.89). Soil water dried fast at the beginning of the irrigation and decreased with time and soil depth, which were consistent with the classical soil drying theory and experiments. It was also found that the soil dried fast in the loamy and duplex soils across the field, which was attributable to deep drainage and preferential flows. It was concluded that the EnKF approach can be used to better the irrigation practice so that variation in irrigation is minimised and irrigation efficiency is improved by applying variable rates of irrigation across the field. In addition, soil water status can be nowcasted using this method with weather forecast information, which will provide guidance to farmers for real-time irrigation management.

Electrical Acupoint Stimulation for Postoperative Recovery

ClinicalTrials.gov

2018-03-30

Postoperative Complications; Postoperative Nausea and Vomiting; Postoperative Infection; Postoperative Delirium; Postoperative Pneumonia; Deep Vein Thrombosis; Postoperative Retention of Urine; Postoperative Recovery

Electrical Conductivity Model of the Mantle Lithosphere of the Slave Craton (NW Canada) and its tectonic interpretation in the context of Geochemical Results

NASA Astrophysics Data System (ADS)

Lezaeta, P.; Chave, A.; Evans, R.; Jones, A. G.; Ferguson, I.

2002-12-01

The Slave Craton, northwestern Canada, contains the oldest known rocks on Earth, with exposed outcrop over an area of about 600x400 km2. The discovery of economic diamondiferous kimberlite pipes during the early 1990s motivated extensive research in the region. Over the last six years, four types of deep-probing magnetotelluric (MT) surveys were conducted within the framework of diverse geoscientific programs, aimed at determining the regional-scale electrical structures of the craton. Two of the surveys involved novel acquisition; one through frozen lake ice along ice roads during winter, and the second deploying ocean-bottom instrumentation from float planes during summer. The latter surveys required one year of recording between summers, thus allowing long period transfer functions that lead to mantle penetration depths of over 300 km. Two-dimensional modeling of the MT data from along the winter road showed the existence of a high conductivity zone at depths of 80-120 km beneath the central Slave craton. This anomalous region is spatially coincident with an ultradepleted harzburgitic layer in the upper mantle that was interpreted by others to be related to a subducted slab emplaced during the mid-Archean. A 3-D electrical conductivity model of the Slave lithosphere has been obtained, by trial and error, to fit the magnetic transfer and MT response functions from the lake experiments. This 3-D model traces the central Slave conductor as a NE-SW oriented mantle structure. Its NE-SW orientation coincides with that of a late fold belt system, with the first phase of craton-wide plutonism at ca 2630-2590 Ma, three-part subdivision of the craton based on SKS results, and with a G10 (garnet) geochemical mantle boundaries. All of these highlight a NE-SW structural grain to the lithospheric mantle of the craton, in sharp contrast to the N-S grain of the crust. Constraints on the depth range and lateral extension of the electrical conductive structure are obtained through a sensitivity analysis to verify a recent hypothesis about tectonic imbrication of lithosphere emplaced at ca 2.6 Ga in which SE-NW subduction is proposed. If such subduction has taken place, and arc-related or oceanic lithosphere has been trapped in the system, then an enhanced conductivity in the mantle deepening to NW supports the tectonic model.

High conductance surge cable

DOEpatents

Murray, M.M.; Wilfong, D.H.; Lomax, R.E.

1998-12-08

An electrical cable for connecting transient voltage surge suppressors to electrical power panels. A strip of electrically conductive foil defines a longitudinal axis, with a length of an electrical conductor electrically attached to the metallic foil along the longitudinal axis. The strip of electrically conductive foil and the length of an electrical conductor are covered by an insulating material. For impedance matching purposes, triangular sections can be removed from the ends of the electrically conductive foil at the time of installation. 6 figs.

Evolution of AlGaN deep level defects as a function of alloying and compositional grading and resultant impact on electrical conductivity

DOE PAGES

Armstrong, Andrew M.; Allerman, Andrew A.

2017-07-24

AlGaN:Si epilayers with uniform Al compositions of 60%, 70%, 80%, and 90% were grown by metal-organic vapor phase epitaxy along with a compositionally graded, unintentionally doped (UID) AlGaN epilayer with the Al composition varying linearly between 80% and 100%. The resistivity of AlGaN:Si with a uniform composition increased significantly for the Al content of 80% and greater, whereas the graded UID-AlGaN film exhibited resistivity equivalent to 60% and 70% AlGaN:Si owing to polarization-induced doping. Deep level defect studies of both types of AlGaN epilayers were performed to determine why the electronic properties of uniform-composition AlGaN:Si degraded with increased Al content,more » while the electronic properties of graded UID-AlGaN did not. The deep level density of uniform-composition AlGaN:Si increased monotonically and significantly with the Al mole fraction. Conversely, graded-UID AlGaN had the lowest deep level density of all the epilayers despite containing the highest Al composition. These findings indicate that Si doping is an impetus for point defect incorporation in AlGaN that becomes stronger with the increasing Al content. However, the increase in deep level density with the Al content in uniform-composition AlGaN:Si was small compared to the increase in resistivity. This implies that the primary cause for increasing resistivity in AlGaN:Si with the increasing Al mole fraction is not compensation by deep levels but rather increasing activation energy for the Si dopant. As a result, the graded UID-AlGaN films maintained low resistivity because they do not rely on thermal ionization of Si dopants.« less

Evolution of AlGaN deep level defects as a function of alloying and compositional grading and resultant impact on electrical conductivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Armstrong, Andrew M.; Allerman, Andrew A.

AlGaN:Si epilayers with uniform Al compositions of 60%, 70%, 80%, and 90% were grown by metal-organic vapor phase epitaxy along with a compositionally graded, unintentionally doped (UID) AlGaN epilayer with the Al composition varying linearly between 80% and 100%. The resistivity of AlGaN:Si with a uniform composition increased significantly for the Al content of 80% and greater, whereas the graded UID-AlGaN film exhibited resistivity equivalent to 60% and 70% AlGaN:Si owing to polarization-induced doping. Deep level defect studies of both types of AlGaN epilayers were performed to determine why the electronic properties of uniform-composition AlGaN:Si degraded with increased Al content,more » while the electronic properties of graded UID-AlGaN did not. The deep level density of uniform-composition AlGaN:Si increased monotonically and significantly with the Al mole fraction. Conversely, graded-UID AlGaN had the lowest deep level density of all the epilayers despite containing the highest Al composition. These findings indicate that Si doping is an impetus for point defect incorporation in AlGaN that becomes stronger with the increasing Al content. However, the increase in deep level density with the Al content in uniform-composition AlGaN:Si was small compared to the increase in resistivity. This implies that the primary cause for increasing resistivity in AlGaN:Si with the increasing Al mole fraction is not compensation by deep levels but rather increasing activation energy for the Si dopant. As a result, the graded UID-AlGaN films maintained low resistivity because they do not rely on thermal ionization of Si dopants.« less

Geophysical Characterization of Serpentinite Hosted Hydrogeology at the McLaughlin Natural Reserve, Coast Range Ophiolite

NASA Astrophysics Data System (ADS)

Ortiz, Estefania; Tominaga, Masako; Cardace, Dawn; Schrenk, Matthew O.; Hoehler, Tori M.; Kubo, Michael D.; Rucker, Dale F.

2018-01-01

Geophysical remote sensing both on land and at sea has emerged as a powerful approach to characterize in situ water-rock interaction processes in time and space. We conducted 2-D Electrical Resistivity Tomography (ERT) surveys to investigate in situ hydrogeological architecture within the Jurassic age tectonic mélange portion of the Coast Range Ophiolite Microbial Observatory (CROMO) during wet and dry seasons, where water-rock interactive processes are thought to facilitate a subsurface biosphere. Integrating survey tracks traversing two previously drilled wells, QV1,1 and CSW1,1 at the CROMO site with wireline and core data, and the Serpentine Valley site, we successfully documented changes in hydrogeologic properties in the CROMO formation, i.e., lateral and vertical distribution of conductive zones and their temporal behavior that are dependent upon seasonal hydrology. Based on the core-log-ERT integration, we propose a hydrogeological architectural model, in which the formation is composed of three distinct aquifer systems: perched serpentinite aquifer without seasonal dependency (shallow system), well-cemented serpentine confining beds with seasonal dependency (intermediate system), serpentinite aquifer (deep system), and the ultramafic basement that acts as a quasi-aquiclude (below the deep system). The stunning contrast between the seasonality in the surface water availability and groundwater storativity in the formation allowed us to locate zones where serpentinite weathering and possibly deeper serpentinization processes might have taken place. We based our findings primarily on lithological composition and the distribution of the conductive formation, our work highlights the link between serpentinite weathering processes and possible sources of water in time and space.

Groundwater quality under the influence of spent mushroom substrate weathering.

PubMed

Guo, Mingxin

2005-10-01

Nitrate and other solutes resulting from field-weathering of spent mushroom substrate (SMS) percolate into underlying soils and may migrate to groundwater. A field trial was conducted to investigate the potential influences of SMS weathering on groundwater quality. Spent mushroom substrate was deposited at 90 and 150 cm pile depths over a Typic Hapludult and weathered for 2 years. Eight casing wells were installed around the SMS piles to monitor the quality changes of groundwater with a high seasonal water table of 760 cm below the surface. Although leachate solutes had moved more than 200 cm deep in soil from the surface, no significant changes of groundwater quality caused by SMS weathering were observed even one year after removal of the SMS piles (3 years total). The groundwater had pH, electrical conductivity (EC) and dissolved organic carbon (DOC) of 4.3-5.7, 0.2-0.3 dS m(-1) and 0.7-2.2 mg L(-1), respectively. The major inorganic ions were Mg(2+), Ca(2+), Na(+), Cl(-), SO(4)(2-) and NO(3)(-), with a concentration range of 2.5-68.3 mg L(-1). The results suggest that SMS leachate solutes migrated fairly slow in deep subsurface soils of the experimental field. Considering that leachate solutes may move several meters in soil through preferential flow channels, weathering of SMS in fields with a high seasonal groundwater table >or=5 m below the ground is recommended. Conservatively, SMS weathering should be conducted on compact surfaces and leachate be collected and reused as liquid fertilizers.

Effect of Rubidium Incorporation on the Structural, Electrical, and Photovoltaic Properties of Methylammonium Lead Iodide-Based Perovskite Solar Cells.

PubMed

Park, Ik Jae; Seo, Seongrok; Park, Min Ah; Lee, Sangwook; Kim, Dong Hoe; Zhu, Kai; Shin, Hyunjung; Kim, Jin Young

2017-12-06

We report the electrical properties of rubidium-incorporated methylammonium lead iodide ((Rb x MA 1-x )PbI 3 ) films and the photovoltaic performance of (Rb x MA 1-x )PbI 3 film-based p-i-n-type perovskite solar cells (PSCs). The incorporation of a small amount of Rb + (x = 0.05) increases both the open circuit voltage (V oc ) and the short circuit photocurrent density (J sc ) of the PSCs, leading to an improved power conversion efficiency (PCE). However, a high fraction of Rb + incorporation (x = 0.1 and 0.2) decreases the J sc and thus the PCE, which is attributed to the phase segregation of the single tetragonal perovskite phase to a MA-rich tetragonal perovskite phase and a RbPbI 3 orthorhombic phase at high Rb fractions. Conductive atomic force microscopic and admittance spectroscopic analyses reveal that the single-phase (Rb 0.05 MA 0.95 )PbI 3 film has a high electrical conductivity because of a reduced deep-level trap density. We also found that Rb substitution enhances the diode characteristics of the PSC, as evidenced by the reduced reverse saturation current (J 0 ). The optimized (Rb x MA 1-x )PbI 3 PSCs exhibited a PCE of 18.8% with negligible hysteresis in the photocurrent-voltage curve. The results from this work enhance the understanding of the effect of Rb incorporation into organic-inorganic hybrid halide perovskites and enable the exploration of Rb-incorporated mixed perovskites for various applications, such as solar cells, photodetectors, and light-emitting diodes.

Characterization of a dismissed landfill via electrical resistivity tomography and mise-à-la-masse method

NASA Astrophysics Data System (ADS)

De Carlo, Lorenzo; Perri, Maria Teresa; Caputo, Maria Clementina; Deiana, Rita; Vurro, Michele; Cassiani, Giorgio

2013-11-01

Electrical resistivity methods are widely used for environmental applications, and they are particularly useful for the characterization and monitoring of sites where the presence of contamination requires a thorough understanding of the location and movement of water, that can act as a carrier of solutes. One such application is landfill studies, where the strong electrical contrasts between waste, leachate and surrounding formations make electrical methods a nearly ideal tool for investigation. In spite of the advantages, however, electrical investigation of landfills poses also challenges, both logistical and interpretational. This paper presents the results of a study conducted on a dismissed landfill, close to the city of Corigliano d'Otranto, in the Apulia region (Southern Italy). The landfill is located in an abandoned quarry, that was subsequently re-utilized about thirty years ago as a site for urban waste disposal. The waste was thought to be more than 20 m thick, and the landfill bottom was expected to be confined with an HDPE (high-density poli-ethylene) liner. During the digging operations performed to build a nearby new landfill, leachate was found, triggering an in-depth investigation including also non-invasive methods. The principal goal was to verify whether the leachate is indeed confined, and to what extent, by the HDPE liner. We performed both surface electrical resistivity tomography (ERT) and mise-à-la-masse (MALM) surveys, facing the severe challenges posed by the rugged terrain of the abandoned quarry complex. A conductive body, probably associated with leachate, was found as deep as 40 m below the current landfill surface i.e. at a depth much larger than the expected 20 m thickness of waste. Given the logistical difficulties that limit the geometry of acquisition, we utilized synthetic forward modeling in order to confirm/dismiss interpretational hypotheses emerging from the ERT and MALM results. This integration between measurements and modeling helped narrow the alternative interpretations and strengthened the confidence in results, confirming the effectiveness of non-invasive methods in landfill investigation and the importance of modeling in the interpretation of geophysical results.

Method of Fault Detection and Rerouting

NASA Technical Reports Server (NTRS)

Gibson, Tracy L. (Inventor); Medelius, Pedro J. (Inventor); Lewis, Mark E. (Inventor)

2013-01-01

A system and method for detecting damage in an electrical wire, including delivering at least one test electrical signal to an outer electrically conductive material in a continuous or non-continuous layer covering an electrically insulative material layer that covers an electrically conductive wire core. Detecting the test electrical signals in the outer conductive material layer to obtain data that is processed to identify damage in the outer electrically conductive material layer.

Neuroprotection trek--the next generation: neuromodulation I. Techniques--deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation

NASA Technical Reports Server (NTRS)

Andrews, Russell J.

2003-01-01

Neuromodulation denotes controlled electrical stimulation of the central or peripheral nervous system. The three forms of neuromodulation described in this paper-deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation-were chosen primarily for their demonstrated or potential clinical usefulness. Deep brain stimulation is a completely implanted technique for improving movement disorders, such as Parkinson's disease, by very focal electrical stimulation of the brain-a technique that employs well-established hardware (electrode and pulse generator/battery). Vagus nerve stimulation is similar to deep brain stimulation in being well-established (for the treatment of refractory epilepsy), completely implanted, and having hardware that can be considered standard at the present time. Vagus nerve stimulation differs from deep brain stimulation, however, in that afferent stimulation of the vagus nerve results in diffuse effects on many regions throughout the brain. Although use of deep brain stimulation for applications beyond movement disorders will no doubt involve placing the stimulating electrode(s) in regions other than the thalamus, subthalamus, or globus pallidus, the use of vagus nerve stimulation for applications beyond epilepsy-for example, depression and eating disorders-is unlikely to require altering the hardware significantly (although stimulation protocols may differ). Transcranial magnetic stimulation is an example of an external or non-implanted, intermittent (at least given the current state of the hardware) stimulation technique, the clinical value of which for neuromodulation and neuroprotection remains to be determined.

Neuroprotection trek--the next generation: neuromodulation I. Techniques--deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation.

PubMed

Andrews, Russell J

2003-05-01

Neuromodulation denotes controlled electrical stimulation of the central or peripheral nervous system. The three forms of neuromodulation described in this paper-deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation-were chosen primarily for their demonstrated or potential clinical usefulness. Deep brain stimulation is a completely implanted technique for improving movement disorders, such as Parkinson's disease, by very focal electrical stimulation of the brain-a technique that employs well-established hardware (electrode and pulse generator/battery). Vagus nerve stimulation is similar to deep brain stimulation in being well-established (for the treatment of refractory epilepsy), completely implanted, and having hardware that can be considered standard at the present time. Vagus nerve stimulation differs from deep brain stimulation, however, in that afferent stimulation of the vagus nerve results in diffuse effects on many regions throughout the brain. Although use of deep brain stimulation for applications beyond movement disorders will no doubt involve placing the stimulating electrode(s) in regions other than the thalamus, subthalamus, or globus pallidus, the use of vagus nerve stimulation for applications beyond epilepsy-for example, depression and eating disorders-is unlikely to require altering the hardware significantly (although stimulation protocols may differ). Transcranial magnetic stimulation is an example of an external or non-implanted, intermittent (at least given the current state of the hardware) stimulation technique, the clinical value of which for neuromodulation and neuroprotection remains to be determined.

Electrically conductive proppant and methods for detecting, locating and characterizing the electrically conductive proppant

DOEpatents

Cannan, Chad; Bartel, Lewis; Palisch, Terrence; Aldridge, David

2015-01-13

Electrically conductive proppants and methods for detecting, locating, and characterizing same are provided. The electrically conductive proppant can include a substantially uniform coating of an electrically conductive material having a thickness of at least 500 nm. The method can include injecting a hydraulic fluid into a wellbore extending into a subterranean formation at a rate and pressure sufficient to open a fracture therein, injecting into the fracture a fluid containing the electrically conductive proppant, electrically energizing the earth at or near the fracture, and measuring three dimensional (x, y, and z) components of electric and magnetic field responses at a surface of the earth or in an adjacent wellbore.

EFFECTS OF FUNCTIONAL ELECTRICAL STIMULATION IN REHABILITATION WITH HEMIPARESIS PATIENTS

PubMed Central

Tanović, Edina

2009-01-01

Cerebrovascular accident is a focal neurological deficiency occurring suddenly and lasting for more than 24 hours. The purpose of our work is to determine the role of the functional electrical simulation (FES) in the rehabilitation of patients with hemiparesis, which occurred as a consequence of a cerebrovascular accident. This study includes the analysis of two groups of 40 patients with hemiparesis (20 patients with deep hemiparesis and 20 patients with light hemi- paresis), a control group which was only treated with kinesiotherapy and a tested group which was treated with kinesiotherapy and functional electrical stimulation. Both groups of patients were analyzed in respect to their sex and age. Additional analysis of the walking function was completed in accordance with the BI and RAP index. The analysis of the basic demographical data demonstrated that there is no significant difference between the control and tested group. The patients of both groups are equal in respect of age and sex. After 4 weeks of rehabilitation of patients with deep and light hemiparesis there were no statistically significant differences between the groups after evaluation by the BI index. However, a statistically significant difference was noted between the groups by the RAP index among patients with deep hemiparesis. After 8 weeks of rehabilitation the group of patients who were treated with kinesiotherapy and functional electrical stimulation showed better statistically significant results of rehabilitation in respect to the control group with both the BI index and the RAP index (p<0,001). In conclusion, we can state that the patients in rehabilitation after a cerebrovascular accident require rehabilitation longer than 4 weeks. Walking rehabilitation after stroke is faster and more successful if we used functional electrical stimulation, in combination with kinesiotherapy, in patients with disabled extremities. PMID:19284395

Electric-field control of conductance in metal quantum point contacts by electric-double-layer gating

NASA Astrophysics Data System (ADS)

Shibata, K.; Yoshida, K.; Daiguji, K.; Sato, H.; , T., Ii; Hirakawa, K.

2017-10-01

An electric-field control of quantized conductance in metal (gold) quantum point contacts (QPCs) is demonstrated by adopting a liquid-gated electric-double-layer (EDL) transistor geometry. Atomic-scale gold QPCs were fabricated by applying the feedback-controlled electrical break junction method to the gold nanojunction. The electric conductance in gold QPCs shows quantized conductance plateaus and step-wise increase/decrease by the conductance quantum, G0 = 2e2/h, as EDL-gate voltage is swept, demonstrating a modulation of the conductance of gold QPCs by EDL gating. The electric-field control of conductance in metal QPCs may open a way for their application to local charge sensing at room temperature.

Structure of the screening layer near a plane isolated body in the deep vacuum. Part 2. Monoenergetic isotropic flow

NASA Astrophysics Data System (ADS)

Gunko, Yuri F.; Gunko, Natalia A.

2018-05-01

In this paper we consider the problem of determining the structure of the electric field near the surface of a flat insulated body under conditions of a deep vacuum. It is assumed that the emitted particles are electrons leaving the body surface under the influence of ionizing radiation whose velocities distribution near the surface is isotropic. It is estimated the thickness of the screening layer under conditions of stationary emission from a flat surface. The solutio of the problem of determining a stationary self-consistent electric field near the surface is found in a simple analytical form. The thickness of the screening layer is calculated from this formula.

Parametric Study of Radiator Concepts for a Stirling Radioisotope Power System Applicable to Deep Space Mission

NASA Technical Reports Server (NTRS)

Juhasz, Albert J.; Tew, Roy C.; Thieme, Lanny G.

2000-01-01

The Department of Energy (DOE) and the NASA Glenn Research Center are developing a Stirling converter for an advanced radioisotope power system to provide spacecraft onboard electric power for NASA deep space missions. This high-efficiency converter is being evaluated as an alternative to replace the much lower efficiency radioisotope thermoelectric generator (RTG). The current power requirement (six years after beginning of mission (BOM) for a mission to Jupiter) is 210 W(sub e) (watts electric) to be generated by two separate power systems, one on each side of the spacecraft. Both two-converter and four-converter system designs are being considered, depending on the amount of required redundancy.

MT data inversion and sensitivity analysis to image electrical structure of Zagros collision zone

NASA Astrophysics Data System (ADS)

Layegh Haghighi, T.; Montahaei, M.; Oskooi, B.

2018-01-01

Magnetotelluric (MT) data from 46 stations on a 470-km-long profile across the Zagros fold-thrust belt (ZFTB) that marks the Arabia-Eurasia collision zone were inverted to derive 2-D electrical resistivity structure between Busher on the coast of Persian Gulf and Posht-e-Badam, 160 km north east of Yazd. The model includes prominent anomalies in the upper and lower crust, beneath the brittle-ductile transition depth and mostly related to the fluid distribution and sedimentary layers beneath the profile. The conductivities and dimensions of the fault zone conductors (FZCs) and high conductivity zones (HCZs) as the major conductive anomalies in a fault zone conceptual model vary significantly below the different faults accommodated in this region. The enhanced conductivity below the site Z30 correlates well with the main Zagros thrust (MZT), located at the western boundary of Sanandaj-Sirjan zone (SSZ) and known as the transition between the two continents. The depth extent of the huge conductor beneath the south west of the profile, attributed to the thick sedimentary columns of the Arabian crust, cannot be resolved due to the smearing effect of the smoothness constraint employed in the regularized inversion procedure and the sensitivity of MT data to the conductance of the subsurface. We performed different tests to determine the range of 2-D models consistent with the data. Our approach was based on synthetic studies, comprising of hypothesis testing and the use of a priori information throughout the inversion procedure as well as forward modeling. We conclude that the minimum depth extent of the conductive layer beneath the southwest of the profile can be determined as approximately deeper than 15 km and also the screening effect of the conductive overburden is highly intense in this model and prevents the deep structures from being resolved properly.

Electrical conductivity modeling in fractal non-saturated porous media

NASA Astrophysics Data System (ADS)

Wei, W.; Cai, J.; Hu, X.; Han, Q.

2016-12-01

The variety of electrical conductivity in non-saturated conditions is important to study electric conduction in natural sedimentary rocks. The electrical conductivity in completely saturated porous media is a porosity-function representing the complex connected behavior of single conducting phases (pore fluid). For partially saturated conditions, the electrical conductivity becomes even more complicated since the connectedness of pore. Archie's second law is an empirical electrical conductivity-porosity and -saturation model that has been used to predict the formation factor of non-saturated porous rock. However, the physical interpretation of its parameters, e.g., the cementation exponent m and the saturation exponent n, remains questionable. On basis of our previous work, we combine the pore-solid fractal (PSF) model to build an electrical conductivity model in non-saturated porous media. Our theoretical porosity- and saturation-dependent models contain endmember properties, such as fluid electrical conductivities, pore fractal dimension and tortuosity fractal dimension (representing the complex degree of electrical flowing path). We find the presented model with non-saturation-dependent electrical conductivity datasets indicate excellent match between theory and experiments. This means the value of pore fractal dimension and tortuosity fractal dimension change from medium to medium and depends not only on geometrical properties of pore structure but also characteristics of electrical current flowing in the non-saturated porous media.

Literature-Related Discovery (LRD)

DTIC Science & Technology

2007-11-01

accepted) water purification literature. The annular region between the inner and outer circles represents literatures related directly and...procedures (thalamotomy and pallidotomy) destroy regions of the brain that produce the uncontrolled spasmodic movements in PD patients [11]. A...more recent procedure, deep brain stimulation, sends electricity through a probe to normalize electrical activity in the brain region , reversing the

Electrical Behavior on N-Type Dopants in AlGaAs Alloys: Shallow Levels and DX Centers

DTIC Science & Technology

1990-11-01

FORCE OFFICE OF SCIENTIFIC RESEARCH GRANT AFOSR-88-0316 EOSRD-LONDON DEPARTAMENTO DE INGENIERIA ELECTRONICA E.T.S. INGENIEROS DE TELECOMUNICACION ...INGENIEROS DE TELECOMUNICACION . MADRID OCTOBER 1990 2 ABSTRACT The electrical properties of n- type AlxGaixAs, for x > 0.2, are governed by deep donor

Multi-label spacecraft electrical signal classification method based on DBN and random forest

PubMed Central

Li, Ke; Yu, Nan; Li, Pengfei; Song, Shimin; Wu, Yalei; Li, Yang; Liu, Meng

2017-01-01

In spacecraft electrical signal characteristic data, there exists a large amount of data with high-dimensional features, a high computational complexity degree, and a low rate of identification problems, which causes great difficulty in fault diagnosis of spacecraft electronic load systems. This paper proposes a feature extraction method that is based on deep belief networks (DBN) and a classification method that is based on the random forest (RF) algorithm; The proposed algorithm mainly employs a multi-layer neural network to reduce the dimension of the original data, and then, classification is applied. Firstly, we use the method of wavelet denoising, which was used to pre-process the data. Secondly, the deep belief network is used to reduce the feature dimension and improve the rate of classification for the electrical characteristics data. Finally, we used the random forest algorithm to classify the data and comparing it with other algorithms. The experimental results show that compared with other algorithms, the proposed method shows excellent performance in terms of accuracy, computational efficiency, and stability in addressing spacecraft electrical signal data. PMID:28486479

Multi-label spacecraft electrical signal classification method based on DBN and random forest.

PubMed

Li, Ke; Yu, Nan; Li, Pengfei; Song, Shimin; Wu, Yalei; Li, Yang; Liu, Meng

2017-01-01

In spacecraft electrical signal characteristic data, there exists a large amount of data with high-dimensional features, a high computational complexity degree, and a low rate of identification problems, which causes great difficulty in fault diagnosis of spacecraft electronic load systems. This paper proposes a feature extraction method that is based on deep belief networks (DBN) and a classification method that is based on the random forest (RF) algorithm; The proposed algorithm mainly employs a multi-layer neural network to reduce the dimension of the original data, and then, classification is applied. Firstly, we use the method of wavelet denoising, which was used to pre-process the data. Secondly, the deep belief network is used to reduce the feature dimension and improve the rate of classification for the electrical characteristics data. Finally, we used the random forest algorithm to classify the data and comparing it with other algorithms. The experimental results show that compared with other algorithms, the proposed method shows excellent performance in terms of accuracy, computational efficiency, and stability in addressing spacecraft electrical signal data.

Deep-subwavelength magnetic-coupling-dominant interaction among magnetic localized surface plasmons

NASA Astrophysics Data System (ADS)

Gao, Zhen; Gao, Fei; Zhang, Youming; Zhang, Baile

2016-05-01

Magnetic coupling is generally much weaker than electric Coulomb interaction. This also applies to the well-known magnetic "meta-atoms," or split-ring resonators (SRRs) as originally proposed by Pendry et al. [IEEE Trans. Microwave Theory Tech. 47, 2075 (1999), 10.1109/22.798002], in which the associated electric dipole moments usually dictate their interaction. As a result, stereometamaterials, a stack of identical SRRs, were found with electric coupling so strong that the dispersion from merely magnetic coupling was overturned. Recently, other workers have proposed a new concept of magnetic localized surface plasmons, supported on metallic spiral structures (MSSs) at a deep-subwavelength scale. Here, we experimentally demonstrate that a stack of these magnetic "meta-atoms" can have dominant magnetic coupling in both of its two configurations. This allows magnetic-coupling-dominant energy transport along a one-dimensional stack of MSSs, as demonstrated with near-field transmission measurement. Our work not only applies this type of magnetic "meta-atom" into metamaterial construction, but also provides possibilities of magnetic metamaterial design in which the electric interaction no longer takes precedence.

Trap assisted space charge conduction in p-NiO/n-ZnO heterojunction diode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tyagi, Manisha; Tomar, Monika; Gupta, Vinay, E-mail: drguptavinay@gmail.com

2015-06-15

Highlights: • p-NiO/n-ZnO heterojunction diode with enhanced junction parameters has been prepared. • Temperature dependent I–V throw insight into the involved conduction mechanism. • SCLC with exponential trap distribution was found to be the dominant mechanism. • C–V measurement at different frequencies support the presence of traps. - Abstract: The development of short-wavelength p–n junction is essentially important for the realization of transparent electronics for next-generation optoelectronic devices. In the present work, a p–n heterojunction diode based on p-NiO/n-ZnO has been prepared under the optimised growth conditions exhibiting improved electrical and junction parameters. The fabricated heterojunction gives typical current–voltage (I–V)more » characteristics with good rectifying behaviour (rectification ratio ≈ 10{sup 4} at 2 V). The temperature dependent current–voltage characteristics of heterojunction diode have been studied and origin of conduction mechanism is identified. The space-charge limited conduction with exponential trap distribution having deep level trap is found to be the dominant conduction mechanism in the fabricated p–n heterojunction diode. The conduction and valence band discontinuities for NiO/ZnO heterostructure have been determined from the capacitance–voltage (C–V) measurements.« less

Analytical solution of electromagnetic radiation by a vertical electric dipole inside the earth and the effect of atmospheric electrical conductivity inhomogeneity

NASA Astrophysics Data System (ADS)

Mosayebidorcheh, Taha; Hosseinibalam, Fahimeh; Hassanzadeh, Smaeyl

2017-11-01

In this paper, the effect of atmospheric electrical conductivity on the electromagnetic waves radiated by a vertical electric dipole located in the earth, near the surface of the earth, is investigated. As far as electrical conductivity is concerned, the atmosphere is divided into three areas, in which the electrical conductivity changes with altitude. The Maxwell equations in these areas are investigated as well. Using the differential transform method, the differential equation is solved in a way that atmospheric electrical conductivity is variable. Solving the problem in these areas indicates that electrical conductivity in the middle and lower areas of atmosphere may be ignored. However, in the upper areas of atmosphere, the magnitude of the magnetic field in the ionosphere at a frequency of 10 kHz at night is five times smaller when electrical conductivity is considered compared to when it is neglected.

Software Toolbox for Low-Frequency Conductivity and Current Density Imaging Using MRI.

PubMed

Sajib, Saurav Z K; Katoch, Nitish; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

2017-11-01

Low-frequency conductivity and current density imaging using MRI includes magnetic resonance electrical impedance tomography (MREIT), diffusion tensor MREIT (DT-MREIT), conductivity tensor imaging (CTI), and magnetic resonance current density imaging (MRCDI). MRCDI and MREIT provide current density and isotropic conductivity images, respectively, using current-injection phase MRI techniques. DT-MREIT produces anisotropic conductivity tensor images by incorporating diffusion weighted MRI into MREIT. These current-injection techniques are finding clinical applications in diagnostic imaging and also in transcranial direct current stimulation (tDCS), deep brain stimulation (DBS), and electroporation where treatment currents can function as imaging currents. To avoid adverse effects of nerve and muscle stimulations due to injected currents, conductivity tensor imaging (CTI) utilizes B1 mapping and multi-b diffusion weighted MRI to produce low-frequency anisotropic conductivity tensor images without injecting current. This paper describes numerical implementations of several key mathematical functions for conductivity and current density image reconstructions in MRCDI, MREIT, DT-MREIT, and CTI. To facilitate experimental studies of clinical applications, we developed a software toolbox for these low-frequency conductivity and current density imaging methods. This MR-based conductivity imaging (MRCI) toolbox includes 11 toolbox functions which can be used in the MATLAB environment. The MRCI toolbox is available at http://iirc.khu.ac.kr/software.html . Its functions were tested by using several experimental datasets, which are provided together with the toolbox. Users of the toolbox can focus on experimental designs and interpretations of reconstructed images instead of developing their own image reconstruction softwares. We expect more toolbox functions to be added from future research outcomes. Low-frequency conductivity and current density imaging using MRI includes magnetic resonance electrical impedance tomography (MREIT), diffusion tensor MREIT (DT-MREIT), conductivity tensor imaging (CTI), and magnetic resonance current density imaging (MRCDI). MRCDI and MREIT provide current density and isotropic conductivity images, respectively, using current-injection phase MRI techniques. DT-MREIT produces anisotropic conductivity tensor images by incorporating diffusion weighted MRI into MREIT. These current-injection techniques are finding clinical applications in diagnostic imaging and also in transcranial direct current stimulation (tDCS), deep brain stimulation (DBS), and electroporation where treatment currents can function as imaging currents. To avoid adverse effects of nerve and muscle stimulations due to injected currents, conductivity tensor imaging (CTI) utilizes B1 mapping and multi-b diffusion weighted MRI to produce low-frequency anisotropic conductivity tensor images without injecting current. This paper describes numerical implementations of several key mathematical functions for conductivity and current density image reconstructions in MRCDI, MREIT, DT-MREIT, and CTI. To facilitate experimental studies of clinical applications, we developed a software toolbox for these low-frequency conductivity and current density imaging methods. This MR-based conductivity imaging (MRCI) toolbox includes 11 toolbox functions which can be used in the MATLAB environment. The MRCI toolbox is available at http://iirc.khu.ac.kr/software.html . Its functions were tested by using several experimental datasets, which are provided together with the toolbox. Users of the toolbox can focus on experimental designs and interpretations of reconstructed images instead of developing their own image reconstruction softwares. We expect more toolbox functions to be added from future research outcomes.

BEETLE II: Deep Natural Language Understanding and Automatic Feedback Generation for Intelligent Tutoring in Basic Electricity and Electronics

ERIC Educational Resources Information Center

Dzikovska, Myroslava; Steinhauser, Natalie; Farrow, Elaine; Moore, Johanna; Campbell, Gwendolyn

2014-01-01

Within STEM domains, physics is considered to be one of the most difficult topics to master, in part because many of the underlying principles are counter-intuitive. Effective teaching methods rely on engaging the student in active experimentation and encouraging deep reasoning, often through the use of self-explanation. Supporting such…

Hawaii Energy and Environmental Technologies Initiative

DTIC Science & Technology

2005-06-01

include a hydrate synthesis system, benthic pressure chambers to simulate deep seafloor sediment, and specialized instrumentation for high pressure...the high probability that a sulfide/oxygen microbial fuel cell can generate electricity in deep ocean sediments, and that prolonged power generation may...hydrogen generation (using an electrolyser) and storage, and on-line high -resolution gas analysis. In addition to installation and commissioning of

Scientific Encounters of the Mysterious Sea. Reading Activities That Explore the Mysterious Creatures of the Deep Blue Sea. Grades 4-7.

ERIC Educational Resources Information Center

Embry, Lynn

This activity book presents reading activities for grades 4-7 exploring the mysterious creatures of the deep sea. The creatures include: angel sharks; argonauts; barberfish; comb jelly; croakers; electric rays; flying fish; giganturid; lantern fish; narwhals; northern basket starfish; ocean sunfish; Portuguese man-of-war; sea cucumbers; sea…

Corneal-shaping electrode

DOEpatents

Doss, James D.; Hutson, Richard L.

1982-01-01

The disclosure relates to a circulating saline electrode for changing corneal shape in eyes. The electrode comprises a tubular nonconductive electrode housing having an annular expanded base which has a surface substantially matched to a subject corneal surface. A tubular conductive electrode connected to a radiofrequency generating source is disposed within the electrode housing and longitudinally aligned therewith. The electrode has a generally hemispherical head having at least one orifice. Saline solution is circulated through the apparatus and over the cornea to cool the corneal surface while radiofrequency electric current emitted from the electrode flows therefrom through the cornea to a second electrode, on the rear of the head. This current heats the deep corneal stroma and thereby effects corneal reshaping as a biological response to the heat.

The magnetospheric disturbance ring current as a source for probing the deep earth electrical conductivity

USGS Publications Warehouse

Campbell, W.H.

1990-01-01

Two current rings have been observed in the equatorial plane of the earth at times of high geomagnetic activity. An eastward current exists between about 2 and 3.5 earth radii (Re) distant, and a larger, more variable companion current exists between about 4 and 9 Re. These current regions are loaded during geomagnetic substorms. They decay, almost exponentially, after the cessation of the particle influx that attends the solar wind disturbance. This review focuses upon characteristics needed for intelligent use of the ring current as a source for induction probing of the earth's mantle. Considerable difficulties are found with the assumption that Dst is a ring-current index. ?? 1990 Birkha??user Verlag.

Conductive fabric seal

DOEpatents

Livesay, Ronald Jason; Mason, Brandon William; Kuhn, Michael Joseph; Rowe, Nathan Carl

2017-04-04

Disclosed are several examples of a system and method for detecting if an article is being tampered with. Included is a covering made of a substrate that is coated with a layer of an electrically conductive material that forms an electrically conductive surface having an electrical resistance. The covering is configured to at least partially encapsulate the article such that the article cannot be tampered with, without modifying the electrical resistance of the electrically conductive surface of the covering. A sensing device is affixed to the electrically conductive surface of the covering and the sensing device monitors the condition of the covering by producing a signal that is indicative of the electrical resistance of the electrically conductive surface of the covering. A measured electrical resistance that differs from a nominal electrical resistance is indicative of a covering that is being tampered with and an alert is communicated to an observer.

Conductive fabric seal

DOEpatents

Livesay, Ronald Jason; Mason, Brandon William; Kuhn, Michael Joseph; Rowe, Nathan Carl

2015-10-13

Disclosed are several examples of a system and method for detecting if an article is being tampered with. Included is a covering made of a substrate that is coated with a layer of an electrically conductive material that forms an electrically conductive surface having an electrical resistance. The covering is configured to at least partially encapsulate the article such that the article cannot be tampered with, without modifying the electrical resistance of the electrically conductive surface of the covering. A sensing device is affixed to the electrically conductive surface of the covering and the sensing device monitors the condition of the covering by producing a signal that is indicative of the electrical resistance of the electrically conductive surface of the covering. A measured electrical resistance that differs from a nominal electrical resistance is indicative of a covering that is being tampered with and an alert is communicated to an observer.

An analysis of electrical conductivity model in saturated porous media

NASA Astrophysics Data System (ADS)

Cai, J.; Wei, W.; Qin, X.; Hu, X.

2017-12-01

Electrical conductivity of saturated porous media has numerous applications in many fields. In recent years, the number of theoretical methods to model electrical conductivity of complex porous media has dramatically increased. Nevertheless, the process of modeling the spatial conductivity distributed function continues to present challenges when these models used in reservoirs, particularly in porous media with strongly heterogeneous pore-space distributions. Many experiments show a more complex distribution of electrical conductivity data than the predictions derived from the experiential model. Studies have observed anomalously-high electrical conductivity of some low-porosity (tight) formations compared to more- porous reservoir rocks, which indicates current flow in porous media is complex and difficult to predict. Moreover, the change of electrical conductivity depends not only on the pore volume fraction but also on several geometric properties of the more extensive pore network, including pore interconnection and tortuosity. In our understanding of electrical conductivity models in porous media, we study the applicability of several well-known methods/theories to electrical characteristics of porous rocks as a function of pore volume, tortuosity and interconnection, to estimate electrical conductivity based on the micro-geometrical properties of rocks. We analyze the state of the art of scientific knowledge and practice for modeling porous structural systems, with the purpose of identifying current limitations and defining a blueprint for future modeling advances. We compare conceptual descriptions of electrical current flow processes in pore space considering several distinct modeling approaches. Approaches to obtaining more reasonable electrical conductivity models are discussed. Experiments suggest more complex relationships between electrical conductivity and porosity than experiential models, particularly in low-porosity formations. However, the available theoretical models combined with simulations do provide insight to how microscale physics affects macroscale electrical conductivity in porous media.

Nonintrusive Load Monitoring Based on Advanced Deep Learning and Novel Signature.

PubMed

Kim, Jihyun; Le, Thi-Thu-Huong; Kim, Howon

2017-01-01

Monitoring electricity consumption in the home is an important way to help reduce energy usage. Nonintrusive Load Monitoring (NILM) is existing technique which helps us monitor electricity consumption effectively and costly. NILM is a promising approach to obtain estimates of the electrical power consumption of individual appliances from aggregate measurements of voltage and/or current in the distribution system. Among the previous studies, Hidden Markov Model (HMM) based models have been studied very much. However, increasing appliances, multistate of appliances, and similar power consumption of appliances are three big issues in NILM recently. In this paper, we address these problems through providing our contributions as follows. First, we proposed state-of-the-art energy disaggregation based on Long Short-Term Memory Recurrent Neural Network (LSTM-RNN) model and additional advanced deep learning. Second, we proposed a novel signature to improve classification performance of the proposed model in multistate appliance case. We applied the proposed model on two datasets such as UK-DALE and REDD. Via our experimental results, we have confirmed that our model outperforms the advanced model. Thus, we show that our combination between advanced deep learning and novel signature can be a robust solution to overcome NILM's issues and improve the performance of load identification.

Nonintrusive Load Monitoring Based on Advanced Deep Learning and Novel Signature

PubMed Central

Le, Thi-Thu-Huong; Kim, Howon

2017-01-01

Monitoring electricity consumption in the home is an important way to help reduce energy usage. Nonintrusive Load Monitoring (NILM) is existing technique which helps us monitor electricity consumption effectively and costly. NILM is a promising approach to obtain estimates of the electrical power consumption of individual appliances from aggregate measurements of voltage and/or current in the distribution system. Among the previous studies, Hidden Markov Model (HMM) based models have been studied very much. However, increasing appliances, multistate of appliances, and similar power consumption of appliances are three big issues in NILM recently. In this paper, we address these problems through providing our contributions as follows. First, we proposed state-of-the-art energy disaggregation based on Long Short-Term Memory Recurrent Neural Network (LSTM-RNN) model and additional advanced deep learning. Second, we proposed a novel signature to improve classification performance of the proposed model in multistate appliance case. We applied the proposed model on two datasets such as UK-DALE and REDD. Via our experimental results, we have confirmed that our model outperforms the advanced model. Thus, we show that our combination between advanced deep learning and novel signature can be a robust solution to overcome NILM's issues and improve the performance of load identification. PMID:29118809

High conductance surge cable

DOEpatents

Murray, Matthew M.; Wilfong, Dennis H.; Lomax, Ralph E.

1998-01-01

An electrical cable for connecting transient voltage surge suppressers to ectrical power panels. A strip of electrically conductive foil defines a longitudinal axis, with a length of an electrical conductor electrically attached to the metallic foil along the longitudinal axis. The strip of electrically conductive foil and the length of an electrical conductor are covered by an insulating material. For impedance matching purposes, triangular sections can be removed from the ends of the electrically conductive foil at the time of installation.

Electrical conductivity of In2O3 and Ga2O3 after low temperature ion irradiation; implications for instrinsic defect formation and charge neutrality level.

PubMed

Vines, L; Bhoodoo, C; von Wenckstern, H; Grundmann, M

2017-12-13

The evolution of sheet resistance of n-type In 2 O 3 and Ga 2 O 3 exposed to bombardment with MeV 12 C and 28 Si ions at 35 K is studied in situ. While the sheet resistance of Ga 2 O 3 increased by more than eight orders of magnitude as a result of ion irradiation, In 2 O 3 showed a more complex defect evolution and became more conductive when irradiated at the highest doses. Heating up to room temperature reduced the sheet resistivity somewhat, but Ga 2 O 3 remained highly resistive, while In 2 O 3 showed a lower resistance than as deposited samples. Thermal admittance spectroscopy and deep level transient spectroscopy did not reveal new defect levels for irradiation up to [Formula: see text] cm -2 . A model where larger defect complexes preferentially produce donor like defects in In 2 O 3 is proposed, and may reveal a microscopic view of a charge neutrality level within the conduction band, as previously proposed.

Electrical conductivity of In2O3 and Ga2O3 after low temperature ion irradiation; implications for instrinsic defect formation and charge neutrality level

NASA Astrophysics Data System (ADS)

Vines, L.; Bhoodoo, C.; von Wenckstern, H.; Grundmann, M.

2018-01-01

The evolution of sheet resistance of n-type In2O3 and Ga2O3 exposed to bombardment with MeV 12C and 28Si ions at 35 K is studied in situ. While the sheet resistance of Ga2O3 increased by more than eight orders of magnitude as a result of ion irradiation, In2O3 showed a more complex defect evolution and became more conductive when irradiated at the highest doses. Heating up to room temperature reduced the sheet resistivity somewhat, but Ga2O3 remained highly resistive, while In2O3 showed a lower resistance than as deposited samples. Thermal admittance spectroscopy and deep level transient spectroscopy did not reveal new defect levels for irradiation up to 2 × 1012 cm-2. A model where larger defect complexes preferentially produce donor like defects in In2O3 is proposed, and may reveal a microscopic view of a charge neutrality level within the conduction band, as previously proposed.

Ionic-Electronic Ambipolar Transport in Metal Halide Perovskites: Can Electronic Conductivity Limit Ionic Diffusion?

PubMed

Kerner, Ross A; Rand, Barry P

2018-01-04

Ambipolar transport describes the nonequilibrium, coupled motion of positively and negatively charged particles to ensure that internal electric fields remain small. It is commonly invoked in the semiconductor community where the motion of excess electrons and holes drift and diffuse together. However, the concept of ambipolar transport is not limited to semiconductor physics. Materials scientists working on ion conducting ceramics understand ambipolar transport dictates the coupled diffusion of ions and the rate is limited by the ion with the lowest diffusion coefficient. In this Perspective, we review a third application of ambipolar transport relevant to mixed ionic-electronic conducting materials for which the motion of ions is expected to be coupled to electronic carriers. In this unique situation, the ambipolar diffusion model has been successful at explaining the photoenhanced diffusion of metal ions in chalcogenide glasses and other properties of materials. Recent examples of photoenhanced phenomena in metal halide perovskites are discussed and indicate that mixed ionic-electronic ambipolar transport is similarly important for a deep understanding of these emerging materials.

NSTAR Ion Thrusters and Power Processors

NASA Technical Reports Server (NTRS)

Bond, T. A.; Christensen, J. A.

1999-01-01

The purpose of the NASA Solar Electric Propulsion Technology Applications Readiness (NSTAR) project is to validate ion propulsion technology for use on future NASA deep space missions. This program, which was initiated in September 1995, focused on the development of two sets of flight quality ion thrusters, power processors, and controllers that provided the same performance as engineering model hardware and also met the dynamic and environmental requirements of the Deep Space 1 Project. One of the flight sets was used for primary propulsion for the Deep Space 1 spacecraft which was launched in October 1998.

Apparatus for Use in Determining Surface Conductivity at Microwave Frequencies

NASA Technical Reports Server (NTRS)

Hearn, Chase P. (Inventor)

1995-01-01

An apparatus is provided for use in determining surface conductivity of a flat or shaped conductive material at microwave frequencies. A plate has an electrically conductive surface with first and second holes passing through the plate. An electrically conductive material under test (MUT) is maintained in a spaced apart relationship with the electrically conductive surface of the plate by one or more nonconductive spacers. A first coupling loop is electrically shielded within the first hole while a second coupling loop is electrically shielded within the second hole. A dielectric resonator element is positioned between the first and second coupling loops, while also being positioned closer to the MUT than the electrically conductive surface of the plate. Microwave energy at an operating frequency f is supplied from a signal source to the first coupling loop while microwave energy received at the second coupling loop is measured. The apparatus is capable of measuring the Q-factor of the dielectric resonator situated in the 'cavity' existing between the electrically conductive surface of the plate and the MUT. Surface conductivity of the electrically conductive surface can be determined via interpolation using: 1 ) the measured Q-factor with the electrically conductive surface in place, and 2) the measured Q-factor when the MUT is replaced with reference standards having known surface conductivities.

Surface hole gas enabled transparent deep ultraviolet light-emitting diode

NASA Astrophysics Data System (ADS)

Zhang, Jianping; Gao, Ying; Zhou, Ling; Gil, Young-Un; Kim, Kyoung-Min

2018-07-01

The inherent deep-level nature of acceptors in wide-band-gap semiconductors makes p-ohmic contact formation and hole supply difficult, impeding progress for short-wavelength optoelectronics and high-power high-temperature bipolar electronics. We provide a general solution by demonstrating an ultrathin rather than a bulk wide-band-gap semiconductor to be a successful hole supplier and ohmic contact layer. Free holes in this ultrathin semiconductor are assisted to activate from deep acceptors and swept to surface to form hole gases by a large electric field, which can be provided by engineered spontaneous and piezoelectric polarizations. Experimentally, a 6 nm thick AlN layer with surface hole gas had formed p-ohmic contact to metals and provided sufficient hole injection to a 280 nm light-emitting diode, demonstrating a record electrical-optical conversion efficiency exceeding 8.5% at 20 mA (55 A cm‑2). Our approach of forming p-type wide-band-gap semiconductor ohmic contact is critical to realizing high-efficiency ultraviolet optoelectronic devices.

Deep level transient spectroscopic investigation of phosphorus-doped silicon by self-assembled molecular monolayers.

PubMed

Gao, Xuejiao; Guan, Bin; Mesli, Abdelmadjid; Chen, Kaixiang; Dan, Yaping

2018-01-09

It is known that self-assembled molecular monolayer doping technique has the advantages of forming ultra-shallow junctions and introducing minimal defects in semiconductors. In this paper, we report however the formation of carbon-related defects in the molecular monolayer-doped silicon as detected by deep-level transient spectroscopy and low-temperature Hall measurements. The molecular monolayer doping process is performed by modifying silicon substrate with phosphorus-containing molecules and annealing at high temperature. The subsequent rapid thermal annealing drives phosphorus dopants along with carbon contaminants into the silicon substrate, resulting in a dramatic decrease of sheet resistance for the intrinsic silicon substrate. Low-temperature Hall measurements and secondary ion mass spectrometry indicate that phosphorus is the only electrically active dopant after the molecular monolayer doping. However, during this process, at least 20% of the phosphorus dopants are electrically deactivated. The deep-level transient spectroscopy shows that carbon-related defects are responsible for such deactivation.

Positron deep level transient spectroscopy — a new application of positron annihilation to semiconductor physics

NASA Astrophysics Data System (ADS)

Beling, C. D.; Fung, S.; Au, H. L.; Ling, C. C.; Reddy, C. V.; Deng, A. H.; Panda, B. K.

1997-05-01

Recent positron mobility and lifetime measurements made on ac-biased metal on semi-insulating GaAs junctions, which have identified the native EL2 defect through a determination of the characteristic ionization energy of the donor level, are reviewed. It is shown that these measurements point towards a new spectroscopy, tentatively named positron-DLTS (deep level transient spectroscopy), that is the direct complement to conventional DLTS in that it monitors transients in the electric field of the depletion region rather than the inversely related depletion width, as deep levels undergo ionization. In this new spectroscopy, which may be applied to doped material by use of a suitable positron beam, electric field transients are monitored through the Doppler shift of the annihilation radiation resulting from the drift velocity of the positron in the depletion region. Two useful extensions of the new spectroscopy beyond conventional capacitance-DLTS are suggested. The first is that in some instances information on the microstructure of the defect causing the deep level may be inferred from the sensitivity of the positron to vacancy defects of negative and neutral charge states. The second is that the positron annihilation technique is intrinsically much faster than conventional DLTS with the capability of observing transients some 10 6 times faster, thus allowing deep levels (and even shallow levels) to be investigated without problems associated with carrier freeze-out.

Atmospheric Electricity

NASA Astrophysics Data System (ADS)

Aplin, Karen; Fischer, Georg

2018-02-01

Electricity occurs in atmospheres across the Solar System planets and beyond, spanning spectacular lightning displays in clouds of water or dust, to more subtle effects of charge and electric fields. On Earth, lightning is likely to have existed for a long time, based on evidence from fossilized lightning strikes in ancient rocks, but observations of planetary lightning are necessarily much more recent. The generation and observations of lightning and other atmospheric electrical processes, both from within-atmosphere measurements, and spacecraft remote sensing, can be readily studied using a comparative planetology approach, with Earth as a model. All atmospheres contain charged molecules, electrons, and/or molecular clusters created by ionization from cosmic rays and other processes, which may affect an atmosphere's energy balance both through aerosol and cloud formation, and direct absorption of radiation. Several planets are anticipated to host a "global electric circuit" by analogy with the circuit occurring on Earth, where thunderstorms drive current of ions or electrons through weakly conductive parts of the atmosphere. This current flow may further modulate an atmosphere's radiative properties through cloud and aerosol effects. Lightning could potentially have implications for life through its effects on atmospheric chemistry and particle transport. It has been observed on many of the Solar System planets (Earth, Jupiter, Saturn, Uranus, and Neptune) and it may also be present on Venus and Mars. On Earth, Jupiter, and Saturn, lightning is thought to be generated in deep water and ice clouds, but discharges can be generated in dust, as for terrestrial volcanic lightning, and on Mars. Other, less well-understood mechanisms causing discharges in non-water clouds also seem likely. The discovery of thousands of exoplanets has recently led to a range of further exotic possibilities for atmospheric electricity, though lightning detection beyond our Solar System remains a technical challenge to be solved.

Utilities Power Change: Engaging Commercial Customers in Workplace Charging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lommele, Stephen; Dafoe, Wendy

As stewards of an electric grid that is available almost anywhere people park, utilities that support workplace charging are uniquely positioned to help their commercial customers be a part of the rapidly expanding network of charging infrastructure. Utilities understand the distinctive challenges of their customers, have access to technical information about electrical infrastructure, and have deep experience modeling and managing demand for electricity. This case study highlights the experiences of two utilities with workplace charging programs.

Website malfunction: a case report highlighting the danger of using electrical insulating tape for buddy strapping

PubMed Central

Devitt, Brian Meldan; Baker, Joseph F; Fitzgerald, Eilis; McCarthy, Conor

2010-01-01

A case of injury to the third web space of the right hand of a rugby player, as a result of buddy strapping with electrical insulating tape of the little and ring finger, is presented. A deep laceration of the web space and distal palmar fascia resulted, necessitating wound exploration and repair. This case highlights the danger of using electrical insulating tape as a means to buddy strap fingers. PMID:22736733

Conductive network formation of carbon nanotubes in elastic polymer microfibers and its effect on the electrical conductance: Experiment and simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Hyun Woo; Kim, Jeongmin; Sung, Bong June, E-mail: jjpark@chonnam.ac.kr, E-mail: bjsung@sogang.ac.kr

We investigate how the electrical conductance of microfibers (made of polymers and conductive nanofillers) decreases upon uniaxial deformation by performing both experiments and simulations. Even though various elastic conductors have been developed due to promising applications for deformable electronic devices, the mechanism at a molecular level for electrical conductance change has remained elusive. Previous studies proposed that the decrease in electrical conductance would result from changes in either distances or contact numbers between conductive fillers. In this work, we prepare microfibers of single walled carbon nanotubes (SWCNTs)/polyvinyl alcohol composites and investigate the electrical conductance and the orientation of SWCNTs uponmore » uniaxial deformation. We also perform extensive Monte Carlo simulations, which reproduce experimental results for the relative decrease in conductance and the SWCNTs orientation. We investigate the electrical networks of SWCNTs in microfibers and find that the decrease in the electrical conductance upon uniaxial deformation should be attributed to a subtle change in the topological structure of the electrical network.« less

Orientation selective deep brain stimulation

NASA Astrophysics Data System (ADS)

Lehto, Lauri J.; Slopsema, Julia P.; Johnson, Matthew D.; Shatillo, Artem; Teplitzky, Benjamin A.; Utecht, Lynn; Adriany, Gregor; Mangia, Silvia; Sierra, Alejandra; Low, Walter C.; Gröhn, Olli; Michaeli, Shalom

2017-02-01

Objective. Target selectivity of deep brain stimulation (DBS) therapy is critical, as the precise locus and pattern of the stimulation dictates the degree to which desired treatment responses are achieved and adverse side effects are avoided. There is a clear clinical need to improve DBS technology beyond currently available stimulation steering and shaping approaches. We introduce orientation selective neural stimulation as a concept to increase the specificity of target selection in DBS. Approach. This concept, which involves orienting the electric field along an axonal pathway, was tested in the corpus callosum of the rat brain by freely controlling the direction of the electric field on a plane using a three-electrode bundle, and monitoring the response of the neurons using functional magnetic resonance imaging (fMRI). Computational models were developed to further analyze axonal excitability for varied electric field orientation. Main results. Our results demonstrated that the strongest fMRI response was observed when the electric field was oriented parallel to the axons, while almost no response was detected with the perpendicular orientation of the electric field relative to the primary fiber tract. These results were confirmed by computational models of the experimental paradigm quantifying the activation of radially distributed axons while varying the primary direction of the electric field. Significance. The described strategies identify a new course for selective neuromodulation paradigms in DBS based on axonal fiber orientation.

Ice-Borehole Probe

NASA Technical Reports Server (NTRS)

Behar, Alberto; Carsey, Frank; Lane, Arthur; Engelhardt, Herman

2006-01-01

An instrumentation system has been developed for studying interactions between a glacier or ice sheet and the underlying rock and/or soil. Prior borehole imaging systems have been used in well-drilling and mineral-exploration applications and for studying relatively thin valley glaciers, but have not been used for studying thick ice sheets like those of Antarctica. The system includes a cylindrical imaging probe that is lowered into a hole that has been bored through the ice to the ice/bedrock interface by use of an established hot-water-jet technique. The images acquired by the cameras yield information on the movement of the ice relative to the bedrock and on visible features of the lower structure of the ice sheet, including ice layers formed at different times, bubbles, and mineralogical inclusions. At the time of reporting the information for this article, the system was just deployed in two boreholes on the Amery ice shelf in East Antarctica and after successful 2000 2001 deployments in 4 boreholes at Ice Stream C, West Antarctica, and in 2002 at Black Rapids Glacier, Alaska. The probe is designed to operate at temperatures from 40 to +40 C and to withstand the cold, wet, high-pressure [130-atm (13.20-MPa)] environment at the bottom of a water-filled borehole in ice as deep as 1.6 km. A current version is being outfitted to service 2.4-km-deep boreholes at the Rutford Ice Stream in West Antarctica. The probe (see figure) contains a sidelooking charge-coupled-device (CCD) camera that generates both a real-time analog video signal and a sequence of still-image data, and contains a digital videotape recorder. The probe also contains a downward-looking CCD analog video camera, plus halogen lamps to illuminate the fields of view of both cameras. The analog video outputs of the cameras are converted to optical signals that are transmitted to a surface station via optical fibers in a cable. Electric power is supplied to the probe through wires in the cable at a potential of 170 VDC. A DC-to-DC converter steps the supply down to 12 VDC for the lights, cameras, and image-data-transmission circuitry. Heat generated by dissipation of electric power in the probe is removed simply by conduction through the probe housing to the visible features of the lower structure of the ice sheet, including ice layers formed at different times, bubbles, and mineralogical inclusions. At the time of reporting the information for this article, the system was just deployed in two boreholes on the Amery ice shelf in East Antarctica and after successful 2000 2001 deployments in 4 boreholes at Ice Stream C, West Antarctica, and in 2002 at Black Rapids Glacier, Alaska. The probe is designed to operate at temperatures from 40 to +40 C and to withstand the cold, wet, high-pressure [130-atm (13.20-MPa)] environment at the bottom of a water-filled borehole in ice as deep as 1.6 km. A current version is being outfitted to service 2.4-km-deep boreholes at the Rutford Ice Stream in West Antarctica. The probe (see figure) contains a sidelooking charge-coupled-device (CCD) camera that generates both a real-time analog video signal and a sequence of still-image data, and contains a digital videotape recorder. The probe also contains a downward-looking CCD analog video camera, plus halogen lamps to illuminate the fields of view of both cameras. The analog video outputs of the cameras are converted to optical signals that are transmitted to a surface station via optical fibers in a cable. Electric power is supplied to the probe through wires in the cable at a potential of 170 VDC. A DC-to-DC converter steps the supply down to 12 VDC for the lights, cameras, and image-datatransmission circuitry. Heat generated by dissipation of electric power in the probe is removed simply by conduction through the probe housing to the visible features of the lower structure of the ice sheet, including ice layers formed at different times, bubbles, and mineralogical inclusions. At thime of reporting the information for this article, the system was just deployed in two boreholes on the Amery ice shelf in East Antarctica and after successful 2000 2001 deployments in 4 boreholes at Ice Stream C, West Antarctica, and in 2002 at Black Rapids Glacier, Alaska. The probe is designed to operate at temperatures from 40 to +40 C and to withstand the cold, wet, high-pressure [130-atm (13.20-MPa)] environment at the bottom of a water-filled borehole in ice as deep as 1.6 km. A current version is being outfitted to service 2.4-km-deep boreholes at the Rutford Ice Stream in West Antarctica. The probe (see figure) contains a sidelooking charge-coupled-device (CCD) camera that generates both a real-time analog video signal and a sequence of still-image data, and contains a digital videotape recorder. The probe also contains a downward-looking CCD analog video camera, plus halogen lamps to illuminate the fields of view of both cameras. The analog video outputs of the cameras are converted to optical signals that are transmitted to a surface station via optical fibers in a cable. Electric power is supplied to the probe through wires in the cable at a potential of 170 VDC. A DC-to-DC converter steps the supply down to 12 VDC for the lights, cameras, and image-datatransmission circuitry. Heat generated by dissipation of electric power in the probe is removed simply by conduction through the probe housing to the adjacent water and ice.

Power module assembly

DOEpatents

Campbell, Jeremy B [Torrance, CA; Newson, Steve [Redondo Beach, CA

2011-11-15

A power module assembly of the type suitable for deployment in a vehicular power inverter, wherein the power inverter has a grounded chassis, is provided. The power module assembly comprises a conductive base layer electrically coupled to the chassis, an insulating layer disposed on the conductive base layer, a first conductive node disposed on the insulating layer, a second conductive node disposed on the insulating layer, wherein the first and second conductive nodes are electrically isolated from each other. The power module assembly also comprises a first capacitor having a first electrode electrically connected to the conductive base layer, and a second electrode electrically connected to the first conductive node, and further comprises a second capacitor having a first electrode electrically connected to the conductive base layer, and a second electrode electrically connected to the second conductive node.

Lithospheric rheological heterogeneity across an intraplate rift basin (Linfen Basin, North China) constrained from magnetotelluric data: Implications for seismicity and rift evolution

NASA Astrophysics Data System (ADS)

Yin, Yaotian; Jin, Sheng; Wei, Wenbo; Ye, Gaofeng; Jing, Jian'en; Zhang, Letian; Dong, Hao; Xie, Chengliang; Liang, Hongda

2017-10-01

We take the Linfen Basin, which is the most active segment of the Cenozoic intraplate Shanxi Rift, as an example, showing how to use magnetotelluric data to constrain lithospheric rheological heterogeneities of intraplate tectonic zones. Electrical resistivity models, combined with previous rheological numerical simulation, show a good correlation between resistivity and rheological strength, indicating the mechanisms of enhanced conductivity could also be reasons of reduced viscosity. The crust beneath the Linfen Basin shows overall stratified features in both electrical resistivity and rheology. The uppermost crustal conductive layer is dominated by friction sliding-type brittle fracturing. The high-resistivity mid-crust is inferred to be high-viscosity metamorphic basement being intersected by deep fault. The plastic lower crust show significantly high-conductivity feature. Seismicity appears to be controlled by crustal rheological heterogeneity. Micro-earthquakes mainly distribute at the brittle-ductile transition zones as indicated by high- to low-resistivity interfaces or the high pore pressure fault zones while the epicenters of two giant destructive historical earthquakes occur within the high-resistivity and therefore high-strength blocks near the inferred rheological interfaces. The lithosphere-scale lateral rheological heterogeneity along the profile can also be illustrated. The crust and upper mantle beneath the Ordos Block, Lüliang Mountains and Taihang Mountains are of high rheological strength as indicated by large-scale high-resistivity zones while a significant high-conductivity, lithosphere-scale weak zone exists beneath the eastern margin of the Linfen Basin. According to previous geodynamic modeling works, we suggest that this kind of lateral rheological heterogeneity may play an essential role for providing driving force for the formation and evolution of the Shanxi Rift, regional lithospheric deformation and earthquake activities under the far-field effects of the India-Eurasian Collision.

Electrically-conductive proppant and methods for making and using same

DOEpatents

Cannan, Chad; Roper, Todd; Savoy, Steve; Mitchell, Daniel R.

2016-09-06

Electrically-conductive sintered, substantially round and spherical particles and methods for producing such electrically-conductive sintered, substantially round and spherical particles from an alumina-containing raw material. Methods for using such electrically-conductive sintered, substantially round and spherical particles in hydraulic fracturing operations.

Deep level transient spectroscopy (DLTS) on colloidal-synthesized nanocrystal solids.

PubMed

Bozyigit, Deniz; Jakob, Michael; Yarema, Olesya; Wood, Vanessa

2013-04-24

We demonstrate current-based, deep level transient spectroscopy (DLTS) on semiconductor nanocrystal solids to obtain quantitative information on deep-lying trap states, which play an important role in the electronic transport properties of these novel solids and impact optoelectronic device performance. Here, we apply this purely electrical measurement to an ethanedithiol-treated, PbS nanocrystal solid and find a deep trap with an activation energy of 0.40 eV and a density of NT = 1.7 × 10(17) cm(-3). We use these findings to draw and interpret band structure models to gain insight into charge transport in PbS nanocrystal solids and the operation of PbS nanocrystal-based solar cells.

Water demand for electricity in deep decarbonisation scenarios: a multi-model assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mouratiadou, I.; Bevione, M.; Bijl, D. L.

This study assesses the effects of deep electricity decarbonisation and shifts in the choice of power plant cooling technologies on global electricity water demand, using a suite of five integrated assessment models. We find that electricity sector decarbonisation results in co-benefits for water resources primarily due to the phase-out of water-intensive coal-based thermoelectric power generation, although these co-benefits vary substantially across decarbonisation scenarios. Wind and solar photovoltaic power represent a win-win option for both climate and water resources, but further expansion of nuclear or fossil- and biomass-fuelled power plants with carbon capture and storage may result in increased pressures onmore » the water environment. Further to these results, the paper provides insights on the most crucial factors of uncertainty with regards to future estimates of water demand. These estimates varied substantially across models in scenarios where the effects of decarbonisation on the electricity mix were less clear-cut. Future thermal and water efficiency improvements of power generation technologies and demand-side energy efficiency improvements were also identified to be important factors of uncertainty. We conclude that in order to ensure positive effects of decarbonisation on water resources, climate policy should be combined with technology-specific energy and/or water policies.« less

Deep Brain Stimulation of the Subthalamic Nucleus Parameter Optimization for Vowel Acoustics and Speech Intelligibility in Parkinson's Disease

ERIC Educational Resources Information Center

Knowles, Thea; Adams, Scott; Abeyesekera, Anita; Mancinelli, Cynthia; Gilmore, Greydon; Jog, Mandar

2018-01-01

Purpose: The settings of 3 electrical stimulation parameters were adjusted in 12 speakers with Parkinson's disease (PD) with deep brain stimulation of the subthalamic nucleus (STN-DBS) to examine their effects on vowel acoustics and speech intelligibility. Method: Participants were tested under permutations of low, mid, and high STN-DBS frequency,…

Movement and Maneuver in Deep Space: A Framework to Leverage Advanced Propulsion

DTIC Science & Technology

2017-04-01

array of benefits for the current National Security Enterprise, and for this reason alone demands attention in the form of disciplined investment...discusses a theoretical organization formed and chartered to develop, test, and acquire deep space propulsion technology and includes what the...different forms , particularly via multi-mode propulsion where both chemical thrusters and electric propulsion devices operate on a common

Hydrometric, Hydrochemical, and Hydrogeophysical Runoff Characterization Across Multiple Land Covers in the Agua Salud Project, Panama

NASA Astrophysics Data System (ADS)

Litt, Guy Finley

As the Panama Canal Authority faces sensitivity to water shortages, managing water resources becomes crucial for the global shipping industry's security. These studies address knowledge gaps in tropical water resources to aid hydrological model development and validation. Field-based hydrological investigations in the Agua Salud Project within the Panama Canal Watershed employed multiple tools across a variety of land covers to investigate hydrological processes. Geochemical tracers informed where storm runoff in a stream comes from and identified electrical conductivity (EC) as an economical, high sample frequency tracer during small storms. EC-based hydrograph separation coupled with hydrograph recession rate analyses identified shallow and deep groundwater storage-discharge relationships that varied by season and land cover. A series of plot-scale electrical resistivity imaging geophysical experiments coupled with rainfall simulation characterized subsurface flow pathway behavior and quantified respectively increasing infiltration rates across pasture, 10 year old secondary succession forest, teak (tectona grandis), and 30 year old secondary succession forest land covers. Additional soil water, groundwater, and geochemical studies informed conceptual model development in subsurface flow pathways and groundwater, and identified future research needs.

Advances in Carbon Nanotubes-Hydrogel Hybrids in Nanomedicine for Therapeutics.

PubMed

Vashist, Arti; Kaushik, Ajeet; Vashist, Atul; Sagar, Vidya; Ghosal, Anujit; Gupta, Y K; Ahmad, Sharif; Nair, Madhavan

2018-05-01

In spite of significant advancement in hydrogel technology, low mechanical strength and lack of electrical conductivity have limited their next-level biomedical applications for skeletal muscles, cardiac and neural cells. Host-guest chemistry based hybrid nanocomposites systems have gained attention as they completely overcome these pitfalls and generate bioscaffolds with tunable electrical and mechanical characteristics. In recent years, carbon nanotube (CNT)-based hybrid hydrogels have emerged as innovative candidates with diverse applications in regenerative medicines, tissue engineering, drug delivery devices, implantable devices, biosensing, and biorobotics. This article is an attempt to recapitulate the advancement in synthesis and characterization of hybrid hydrogels and provide deep insights toward their functioning and success as biomedical devices. The improved comparative performance and biocompatibility of CNT-hydrogels hybrids systems developed for targeted biomedical applications are addressed here. Recent updates toward diverse applications and limitations of CNT hybrid hydrogels is the strength of the review. This will provide a holistic approach toward understanding of CNT-based hydrogels and their applications in nanotheranostics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal Development Test of the NEXT PM1 ION Engine

NASA Technical Reports Server (NTRS)

Anderson, John R.; Snyder, John Steven; Van Noord, Jonathan L.; Soulas, George C.

2007-01-01

NASA's Evolutionary Xenon Thruster (NEXT) is a next-generation high-power ion thruster under development by NASA as a part of the In-Space Propulsion Technology Program. NEXT is designed for use on robotic exploration missions of the solar system using solar electric power. Potential mission destinations that could benefit from a NEXT Solar Electric Propulsion (SEP) system include inner planets, small bodies, and outer planets and their moons. This range of robotic exploration missions generally calls for ion propulsion systems with deep throttling capability and system input power ranging from 0.6 to 25 kW, as referenced to solar array output at 1 Astronomical Unit (AU). Thermal development testing of the NEXT prototype model 1 (PM1) was conducted at JPL to assist in developing and validating a thruster thermal model and assessing the thermal design margins. NEXT PM1 performance prior to, during and subsequent to thermal testing are presented. Test results are compared to the predicted hot and cold environments expected missions and the functionality of the thruster for these missions is discussed.

Thermal Development Test of the NEXT PM1 Ion Engine

NASA Technical Reports Server (NTRS)

Anderson, John R.; Snyder, John S.; VanNoord, Jonathan L.; Soulas, George C.

2010-01-01

NASA's Evolutionary Xenon Thruster (NEXT) is a next-generation high-power ion propulsion system under development by NASA as a part of the In-Space Propulsion Technology Program. NEXT is designed for use on robotic exploration missions of the solar system using solar electric power. Potential mission destinations that could benefit from a NEXT Solar Electric Propulsion (SEP) system include inner planets, small bodies, and outer planets and their moons. This range of robotic exploration missions generally calls for ion propulsion systems with deep throttling capability and system input power ranging from 0.6 to 25 kW, as referenced to solar array output at 1 Astronomical Unit (AU). Thermal development testing of the NEXT prototype model 1 (PM1) was conducted at JPL to assist in developing and validating a thruster thermal model and assessing the thermal design margins. NEXT PM1 performance prior to, during and subsequent to thermal testing are presented. Test results are compared to the predicted hot and cold environments expected missions and the functionality of the thruster for these missions is discussed.

Electrical behaviour of fully solution processed HfO2 (MOS) in presence of different light illumination

NASA Astrophysics Data System (ADS)

Mondal, Sandip

2018-04-01

This experiment demonstrates the electrical behaviors of fully solution processed HfO2(MOS) in presence of different optical illumination. The capacitance voltage measurement was performed at frequency of 100 kHz with a DC gate sweep voltage of ±5V (with additional AC voltage of 100mV) in presence of deep UV (wavelength of 365nm with power of 25W) as well as white light (20W). It is found that there is a large shift in flatband voltage of 120mV due presence of white light during the CV measurement. However there is negligible change in flatband voltage (30mV) has been observed due to illumination of deep UV light.

Deep brain stimulation of the subthalamic nucleus enhances emotional processing in Parkinson disease.

PubMed

Schneider, Frank; Habel, Ute; Volkmann, Jens; Regel, Sabine; Kornischka, Jürgen; Sturm, Volker; Freund, Hans-Joachim

2003-03-01

High-frequency electrical stimulation of the subthalamic nucleus is a new and highly effective therapy for complications of long-term levodopa therapy and motor symptoms in advanced Parkinson disease (PD). Clinical observations indicate additional influence on emotional behavior. Electrical stimulation of deep brain nuclei with pulse rates above 100 Hz provokes a reversible, lesioning-like effect. Here, the effect of deep brain stimulation of the subthalamic nucleus on emotional, cognitive, and motor performance in patients with PD (n = 12) was examined. The results were compared with the effects of a suprathreshold dose of levodopa intended to transiently restore striatal dopamine deficiency. Patients were tested during medication off/stimulation off (STIM OFF), medication off/stimulation on (STIM ON), and during the best motor state after taking levodopa without deep brain stimulation (MED). More positive self-reported mood and an enhanced mood induction effect as well as improvement in emotional memory during STIM ON were observed, while during STIM OFF, patients revealed reduced emotional performance. Comparable effects were revealed by STIM ON and MED. Cognitive performance was not affected by the different conditions and treatments. Deep brain stimulation of the subthalamic nucleus selectively enhanced affective processing and subjective well-being and seemed to be antidepressive. Levodopa and deep brain stimulation had similar effects on emotion. This finding may provide new clues about the neurobiologic bases of emotion and mood disorders, and it illustrates the important role of the basal ganglia and the dopaminergic system in emotional processing in addition to the well-known motor and cognitive functions.

Experimental Study on the Electrical Conductivity of Pyroxene Andesite at High Temperature and High Pressure

NASA Astrophysics Data System (ADS)

Hui, KeShi; Dai, LiDong; Li, HePing; Hu, HaiYing; Jiang, JianJun; Sun, WenQing; Zhang, Hui

2017-03-01

The electrical conductivity of pyroxene andesite was in situ measured under conditions of 1.0-2.0 GPa and 673-1073 K using a YJ-3000t multi-anvil press and Solartron-1260 Impedance/Gain-phase analyzer. Experimental results indicate that the electrical conductivities of pyroxene andesite increase with increasing temperature, and the electrical conductivities decrease with the rise of pressure, and the relationship between electrical conductivity ( σ) and temperature ( T) conforms to an Arrhenius relation within a given pressure and temperature range. When temperature rises up to 873-923 K, the electrical conductivities of pyroxene andesite abruptly increase, and the activation enthalpy increases at this range, which demonstrates that pyroxene andesite starts to dehydrate. By the virtue of the activation enthalpy (0.35-0.42 eV) and the activation volume (-6.75 ± 1.67 cm3/mole) which characterizes the electrical properties of sample after dehydration, we consider that the conduction mechanism is the small polaron conduction before and after dehydration, and that the rise of carrier concentration is the most important reason of increased electrical conductivity.

Electrically conductive cellulose composite

DOEpatents

Evans, Barbara R.; O'Neill, Hugh M.; Woodward, Jonathan

2010-05-04

An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at 25.degree. C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

Designing skin response meter for psycho galvanic reflex

NASA Astrophysics Data System (ADS)

Dhokalia, Dhruv M.; Atreya, Parul; Kumar, Arun

2011-12-01

Human skin offers some resistance to current and voltage. This resistance changes with the emotional state of the body. The circuit proposed here measures changes in our skin resistance following changes in our mental state. In the relaxed state, the resistance offered by the skin is as high as 2 mega-ohms or more, which reduces to 500 kilo-ohms or less when the emotional stress is too high. The reduction in skin resistance is related to increased blood flow and permeability followed by the physiological changes during high stress. This increases the electrical conductivity of the skin. This circuit is useful to monitor the skin's response to relaxation techniques. It is very sensitive and shows response during a sudden moment of stress. Even a deep sigh will give response in the circuit. The circuit uses a sensitive amplifier to sense variations in the skin resistance. IC CA3140 is designed as a resistance- to-voltage converter that outputs varying voltage based on the skin's conductivity.

Assessing environmental risk of the retired filter bed area, Battelle West Jefferson

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, S.F.; Thompson, M.D.; Glennon, M.A.

1997-04-01

Initial investigations conducted by the U.S. Department of Energy, Chicago Operations Office, and by Argonne National Laboratory used seismic refraction profiling, electrical resistivity depth sounding, conductivity profiling, magnetic gradiometry, and ground-penetrating radar to study environmental geophysics in the area of the Battelle West Jefferson site`s radiologically contaminated retired filter beds. The investigators used a combination of nonintrusive technologies and innovative drilling techniques to assess environmental risk at the filter beds and to improve understanding of the geology of the Big Darby Creek floodplain. The geophysical investigation, which showed that the preferred groundwater pathway is associated with a laterally extensive depositmore » of silty sand to sand that is less than 12 ft deep in the floodplain area, also guided the location of cone penetrometer test sites and piezometer installation. Cone penetrometer testing was useful for comparing continuous logging data with surface geophysical data in establishing correlations among unconsolidated materials.« less

Experimental analysis of electrical properties of composite materials

NASA Astrophysics Data System (ADS)

Fiala, L.; Rovnaník, P.; Černý, R.

2017-02-01

Dry cement-based composites are electrically non-conductive materials that behave in electric field like dielectrics. However, a relatively low amount of electrically conductive admixture significantly increases the electrical conductivity which extends applicability of such materials in practice. Therefore, they can be used as self-monitoring sensors controlling development of cracks; as sensors monitoring moisture content or when treated by an external electrical voltage as heat sources used for deicing of material's surface layer. Alkali-activated aluminosilicates (AAA), as competing materials to cement-based materials, are intensively investigated in the present due to their superior durability and environmental impact. Whereas the electrical properties of AAA are similar to those cement-based, they can be enhanced in the same way. In both cases, it is crucial to find a reasonable amount of electrically conductive phase to design composites with a sufficient electrical conductivity at an affordable price. In this paper, electrical properties of composites based on AAA binder and electrically conductive admixture represented by carbon nanotubes (CNT) are investigated. Measurements of electrical properties are carried out by means of 2-probes DC technique on nine types of samples; reference sample without the conductive phase and samples with CNT admixture in amount of 0.1 % - 2.5 % by vol. A significant increase of the electrical conductivity starts from the amount of 0.5 % CNT admixture and in case of 2.5 % CNT is about three orders of magnitude higher compared to the reference sample.

TOPICAL REVIEW: The shallow-to-deep instability of hydrogen and muonium in II VI and III V semiconductors

NASA Astrophysics Data System (ADS)

Cox, S. F. J.

2003-11-01

The structure and electrical activity of monatomic hydrogen defect centres are inferred from the spectroscopy and charge-state transitions of muonium, the light pseudo-isotope of hydrogen. Introductions are given to all these topics. Special attention is paid to the shallow-donor behaviour recently established in a number of II VI compounds and one III nitride. This contrasts with trapped-atom states suggestive of an acceptor function in other members of the II VI family as well as with the deep-level amphoteric behaviour which has long been known in the elemental group-IV semiconductors and certain III V compounds. The systematics of this remarkable shallow-to-deep instability are examined in terms of simple chemical considerations, as well as current theoretical and computational models. The muonium data appear to confirm predictions that the switch from shallow to deep behaviour is governed primarily by the depth of the conduction-band minimum below the vacuum continuum. The threshold electron affinity is around 3.5 eV, which compares favourably with computational estimates of a so-called pinning level for hydrogen (+/-) charge-state transitions of between -3 and -4.5 eV. A purely ionic model gives some intuitive understanding of this behaviour as well as the invariance of the threshold. Another current description applies equally to covalent materials and relates the threshold to the origin of the electrochemical scale. At the present level of approximation, zero-point energy corrections to the transition levels are small, so that muonium data should provide a reliable guide to the behaviour of hydrogen. Muonium spectroscopy proves to be more sensitive to the (0/+) donor level than to the (+/-) pinning level but, as a tool which does not rely on favourable hydrogen solubility, it looks set to test further predictions of these models in a large number of other materials, notably oxides. Certain candidate thin-film insulators and high-permittivity gate dielectrics appear to be uncomfortably close to conditions in which hydrogen impurity may cause electronic conduction.

Electromagnetic Field Modeling of Transcranial Electric and Magnetic Stimulation: Targeting, Individualization, and Safety of Convulsive and Subconvulsive Applications

NASA Astrophysics Data System (ADS)

Deng, Zhi-De

The proliferation of noninvasive transcranial electric and magnetic brain stimulation techniques and applications in recent years has led to important insights into brain function and pathophysiology of brain-based disorders. Transcranial electric and magnetic stimulation encompasses a wide spectrum of methods that have developed into therapeutic interventions for a variety of neurological and psychiatric disorders. Although these methods are at different stages of development, the physical principle underlying these techniques is the similar. Namely, an electromagnetic field is induced in the brain either via current injection through scalp electrodes or via electromagnetic induction. The induced electric field modulates the neuronal transmembrane potentials and, thereby, neuronal excitability or activity. Therefore, knowledge of the induced electric field distribution is key in the design and interpretation of basic research and clinical studies. This work aims to delineate the fundamental physical limitations, tradeoffs, and technological feasibility constraints associated with transcranial electric and magnetic stimulation, in order to inform the development of technologies that deliver safer, and more spatially, temporally, and patient specific stimulation. Part I of this dissertation expounds on the issue of spatial targeting of the electric field. Contrasting electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) configurations that differ markedly in efficacy, side effects, and seizure induction efficiency could advance our understanding of the principles linking treatment parameters and therapeutic outcome and could provide a means of testing hypotheses of the mechanisms of therapeutic action. Using the finite element method, we systematically compare the electric field characteristics of existing forms of ECT and MST. We introduce a method of incorporating a modality-specific neural activation threshold in the electric field models that can inform dosage requirements in convulsive therapies. Our results indicate that the MST electric field is more focal and more confined to the superficial cortex compared to ECT. Further, the conventional ECT current amplitude is much higher than necessary for seizure induction. One of the factors important to clinical outcome is seizure expression. However, it is unknown how the induced electric field is related to seizure onset and propagation. In this work, we explore the effect of the electric field distribution on the quantitative ictal electroencephalography and current source density in ECT and MST. We further demonstrate how the ECT electrode shape, size, spacing, and current can be manipulated to yield more precise control of the induced electric field. If desirable, ECT can be made as focal as MST while using simpler stimulation equipment. Next, we demonstrate how the electric field induced by transcranial magnetic stimulation (TMS) can be controlled. We present the most comprehensive comparison of TMS coil electric field penetration and focality to date. The electric field distributions of more than 50 TMS coils were simulated. We show that TMS coils differ markedly in their electric field characteristics, but they all are subject to a consistent depth-focality tradeoff. Specifically, the ability to directly stimulate deeper brain structures is obtained at the expense of inducing wider electric field spread. Figure-8 type coils are fundamentally more focal compared to circular type coils. Understanding the depth-focality tradeoff can help researchers and clinicians to appropriately select coils and interpret TMS studies. This work also enables the development of novel TMS coils with electronically switchable active and sham modes as well as for deep TMS. Design considerations of these coils are extensively discussed. Part II of the dissertation aims to quantify the effect of individual, sex, and age differences in head geometry and conductivity on the induced neural stimulation strength and focality of ECT and MST. Across and within ECT studies, there is marked unexplained variability in seizure threshold and clinical outcomes. It is not known to what extent the age and sex effects on seizure threshold are mediated by interindividual variation in neural excitability and/or anatomy of the head. Addressing this question, we examine the effect on ECT and MST induced field characteristics of the variability in head diameter, scalp and skull thicknesses and conductivities, as well as brain volume, in a range of values that are representative of the patient population. Variations in the local tissue properties such as scalp and skull thickness and conductivity affect the existing ECT configurations more than MST. On the other hand, the existing MST coil configurations show greater sensitivity to head diameter variation compared to ECT. Due to the high focality of MST compared to ECT, the stimulated brain volume in MST is more sensitive to variation in tissue layer thicknesses. We further demonstrate how individualization of the stimulus pulse current amplitude, which is not presently done in ECT or MST, can be used as a means of compensating for interindividual anatomical variability, which could lead to better and more consistent clinical outcomes. Part III of the dissertation aims to systemically investigate, both computationally and experimentally, the safety of TMS and ECT in patients with a deep-brain stimulation system, and propose safety guidelines for the dual-device therapy. We showed that the induction of significant voltages in the subcutaneous leads in the scalp during TMS could result in unintended and potentially dangerous levels of electrical currents in the DBS electrode contacts. When applying ECT in patients with intracranial implants, we showed that there is an increase in the electric field strength in the brain due to conduction through the burr holes, especially when the burr holes are not fitted with nonconductive caps. Safety concerns presently limit the access of patients with intracranial electronic devices to therapies involving transcranial stimulation technology, which may preclude them from obtaining appropriate medical treatments. Gaining better understanding of the interactions between transcranial and implanted stimulation devices will demarcate significant safety risks from benign interactions, and will provide recommendations for reducing risk, thus enhancing the patient's therapeutic options.

Electro-Quasistatic Simulations in Bio-Systems Engineering and Medical Engineering

NASA Astrophysics Data System (ADS)

van Rienen, U.; Flehr, J.; Schreiber, U.; Schulze, S.; Gimsa, U.; Baumann, W.; Weiss, D. G.; Gimsa, J.; Benecke, R.; Pau, H.-W.

2005-05-01

Slowly varying electromagnetic fields play a key role in various applications in bio-systems and medical engineering. Examples are the electric activity of neurons on neurochips used as biosensors, the stimulating electric fields of implanted electrodes used for deep brain stimulation in patients with Morbus Parkinson and the stimulation of the auditory nerves in deaf patients, respectively. In order to simulate the neuronal activity on a chip it is necessary to couple Maxwell's and Hodgkin-Huxley's equations. First numerical results for a neuron coupling to a single electrode are presented. They show a promising qualitative agreement with the experimentally recorded signals. Further, simulations are presented on electrodes for deep brain stimulation in animal experiments where the question of electrode ageing and energy deposition in the surrounding tissue are of major interest. As a last example, electric simulations for a simple cochlea model are presented comparing the field in the skull bones for different electrode types and stimulations in different positions.

Deep Brain Electrical Stimulation in Epilepsy

NASA Astrophysics Data System (ADS)

Rocha, Luisa L.

2008-11-01

The deep brain electrical stimulation has been used for the treatment of neurological disorders such as Parkinson's disease, chronic pain, depression and epilepsy. Studies carried out in human brain indicate that the application of high frequency electrical stimulation (HFS) at 130 Hz in limbic structures of patients with intractable temporal lobe epilepsy abolished clinical seizures and significantly decreased the number of interictal spikes at focus. The anticonvulsant effects of HFS seem to be more effective in patients with less severe epilepsy, an effect associated with a high GABA tissue content and a low rate of cell loss. In addition, experiments using models of epilepsy indicate that HFS (pulses of 60 μs width at 130 Hz at subthreshold current intensity) of specific brain areas avoids the acquisition of generalized seizures and enhances the postictal seizure suppression. HFS is also able to modify the status epilepticus. It is concluded that the effects of HFS may be a good strategy to reduce or avoid the epileptic activity.

Effects of sub-bandgap illumination on electrical properties and detector performances of CdZnTe:In

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Lingyan; Jie, Wanqi, E-mail: jwq@nwpu.edu.cn; Zha, Gangqiang, E-mail: zha-gq@hotmail.com

2014-06-09

The effects of sub-bandgap illumination on electrical properties of CdZnTe:In crystals and spectroscopic performances of the fabricated detectors were discussed. The excitation process of charge carriers through thermal and optical transitions at the deep trap could be described by the modified Shockley-Read-Hall model. The ionization probability of the deep donor shows an increase under illumination, which should be responsible for the variation of electrical properties within CdZnTe bulk materials with infrared (IR) irradiation. By applying Ohm's law, diffusion model and interfacial layer-thermionic-diffusion theory, we obtain the decrease of bulk resistivity and the increase of space charge density in the illuminatedmore » crystals. Moreover, the illumination induced ionization will further contribute to improving carrier transport property and charge collection efficiency. Consequently, the application of IR irradiation in the standard working environment is of great significance to improve the spectroscopic characteristics of CdZnTe radiation detectors.« less

Method of forming an electrically conductive cellulose composite

DOEpatents

Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Woodward, Jonathan [Ashtead, GB

2011-11-22

An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at 25.degree. C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

3D soil water nowcasting using electromagnetic conductivity imaging and the ensemble Kalman filter

NASA Astrophysics Data System (ADS)

Huang, Jingyi; McBratney, Alex B.; Minasny, Budiman; Triantafilis, John

2017-06-01

Mapping and immediate forecasting of soil water content (θ) and its movement can be challenging. Although inversion of apparent electrical conductivity (ECa) measured by electromagnetic induction to calculate depth-specific electrical conductivity (σ) has been used, it is difficult to apply it across a field. In this paper we use a calibration established along a transect, across a 3.94-ha field with varying soil texture, using an ensemble Kalman filter (EnKF) to monitor and nowcast the 3-dimensional θ dynamics on 16 separate days over a period of 38 days. The EnKF combined a physical model fitted with θ measured by soil moisture sensors and an Artificial Neural Network model comprising σ generated by quasi-3d inversions of DUALEM-421S ECa data. Results showed that the distribution of θ was controlled by soil texture, topography, and vegetation. Soil water dried fastest at the beginning after the initial irrigation event and decreased with time and soil depth, which was consistent with classical soil drying theory and experiments. It was also found that the soil dried fastest in the loamy and duplex soils present in the field, which was attributable to deep drainage and preferential flow. It was concluded that the EnKF approach can be used to improve the irrigation efficiency by applying variable irrigation rates across the field. In addition, soil water status can be nowcasted across large spatial extents using this method with weather forecast information, which will provide guidance to farmers for real-time irrigation management.

Magnetotelluric Imaging of Lower Crustal Melt and Lithospheric Hydration in the Rocky Mountain Front Transition Zone, Colorado, USA

NASA Astrophysics Data System (ADS)

Feucht, D. W.; Sheehan, A. F.; Bedrosian, P. A.

2017-12-01

We present an electrical resistivity model of the crust and upper mantle from two-dimensional (2-D) anisotropic inversion of magnetotelluric data collected along a 450 km transect of the Rio Grande rift, southern Rocky Mountains, and High Plains in Colorado, USA. Our model provides a window into the modern-day lithosphere beneath the Rocky Mountain Front to depths in excess of 150 km. Two key features of the 2-D resistivity model are (1) a broad zone ( 200 km wide) of enhanced electrical conductivity (<20 Ωm) in the midcrust to lower crust that is centered beneath the highest elevations of the southern Rocky Mountains and (2) hydrated lithospheric mantle beneath the Great Plains with water content in excess of 100 ppm. We interpret the high conductivity region of the lower crust as a zone of partially molten basalt and associated deep-crustal fluids that is the result of recent (less than 10 Ma) tectonic activity in the region. The recent supply of volatiles and/or heat to the base of the crust in the late Cenozoic implies that modern-day tectonic activity in the western United States extends to at least the western margin of the Great Plains. The transition from conductive to resistive upper mantle is caused by a gradient in lithospheric modification, likely including hydration of nominally anhydrous minerals, with maximum hydration occurring beneath the Rocky Mountain Front. This lithospheric "hydration front" has implications for the tectonic evolution of the continental interior and the mechanisms by which water infiltrates the lithosphere.

The effect of different surfactants/plastisizers on the electrical behavior of CNT nano-modified cement mortars

NASA Astrophysics Data System (ADS)

Dalla, P. T.; Alafogianni, P.; Tragazikis, I. K.; Exarchos, D. A.; Dassios, K.; Barkoula, N.-M.; Matikas, T. E.

2015-03-01

Cement-based materials have in general low electrical conductivity. Electrical conductivity is the measure of the ability of the material to resist the passage of electrical current. The addition of a conductive admixture such as Multi-Walled Carbon Nanotubes (MWCNTs) in a cement-based material increases the conductivity of the structure. This research aims to characterize nano-modified cement mortars with MWCNT reinforcements. Such nano-composites would possess smartness and multi-functionality. Multifunctional properties include electrical, thermal and piezo-electric characteristics. One of these properties, the electrical conductivity, was measured using a custom made apparatus that allows application of known D.C. voltage on the nano-composite. In this study, the influence of different surfactants/plasticizers on CNT nano-modified cement mortar specimens with various concentrations of CNTs (0.2% wt. cement CNTs - 0.8% wt. cement CNTs) on the electrical conductivity is assessed.

Electromagnetic interference filter for automotive electrical systems

DOEpatents

Herron, Nicholas Hayden; Carlson, Douglas S; Tang, David; Korich, Mark D

2013-07-02

A filter for an automotive electrical system includes a substrate having first and second conductive members. First and second input terminals are mounted to the substrate. The first input terminal is electrically connected to the first conductive member, and the second input terminal is electrically connected to the second conductive member. A plurality of capacitors are mounted to the substrate. Each of the capacitors is electrically connected to at least one of the first and second conductive members. First and second power connectors are mounted to the substrate. The first power connector is electrically connected to the first conductive member, and the second power connector is electrically connected to the second conductive member. A common mode choke is coupled to the substrate and arranged such that the common mode choke extends around at least a portion of the substrate and the first and second conductive members.

Ultrahigh Oxidation Resistance and High Electrical Conductivity in Copper-Silver Powder.

PubMed

Li, Jiaxiang; Li, Yunping; Wang, Zhongchang; Bian, Huakang; Hou, Yuhang; Wang, Fenglin; Xu, Guofu; Liu, Bin; Liu, Yong

2016-12-22

The electrical conductivity of pure Cu powder is typically deteriorated at elevated temperatures due to the oxidation by forming non-conducting oxides on surface, while enhancing oxidation resistance via alloying is often accompanied by a drastic decline of electrical conductivity. Obtaining Cu powder with both a high electrical conductivity and a high oxidation resistance represents one of the key challenges in developing next-generation electrical transferring powder. Here, we fabricate a Cu-Ag powder with a continuous Ag network along grain boundaries of Cu particles and demonstrate that this new structure can inhibit the preferential oxidation in grain boundaries at elevated temperatures. As a result, the Cu-Ag powder displays considerably high electrical conductivity and high oxidation resistance up to approximately 300 °C, which are markedly higher than that of pure Cu powder. This study paves a new pathway for developing novel Cu powders with much enhanced electrical conductivity and oxidation resistance in service.

Investigation of the electrical characteristics of electrically conducting yarns and fabrics

NASA Astrophysics Data System (ADS)

Akbarov, R. D.; Baymuratov, B. H.; Akbarov, D. N.; Ilhamova, M.

2017-11-01

Electro-conductive textile materials and products are used presently giving solutions to the problems, related to static electricity, electromagnetic shielding and electromagnetic radiation. Thus a study of their electro-physical characteristics, character of conductivity, possibility of forecasting of electric parameters etc has a substantial value. This work shows the possibility of production electro-conducting textile materials with stable anti-static properties by introduction of electro-conducting yarn into the structure of fabrics. The results of the research, directed to the study of the electro-physical characteristics of electroconducting yarn and fabrics, are influenced by the frequent washing of polyester fabrics containing the different amounts of electro-conducting filaments in the composition. This article reviews the results of the related research, of the electrical characteristics of the yarn and fabric, of the effect of multiple water treatments on the electrical properties of polyester fabrics, containing in their composition different amounts of electrically conductive yarns.

Integrated Sensing and Information Processing Theme-Based Redesign of the Undergraduate Electrical and Computer Engineering Curriculum at Duke University

ERIC Educational Resources Information Center

Ybarra, Gary A.; Collins, Leslie M.; Huettel, Lisa G.; Brown, April S.; Coonley, Kip D.; Massoud, Hisham Z.; Board, John A.; Cummer, Steven A.; Choudhury, Romit Roy; Gustafson, Michael R.; Jokerst, Nan M.; Brooke, Martin A.; Willett, Rebecca M.; Kim, Jungsang; Absher, Martha S.

2011-01-01

The field of electrical and computer engineering has evolved significantly in the past two decades. This evolution has broadened the field of ECE, and subfields have seen deep penetration into very specialized areas. Remarkable devices and systems arising from innovative processes, exotic materials, high speed computer simulations, and complex…

Effect of Rubidium Incorporation on the Structural, Electrical, and Photovoltaic Properties of Methylammonium Lead Iodide-Based Perovskite Solar Cells

DOE PAGES

Park, Ik Jae; Seo, Seongrok; Park, Min Ah; ...

2017-11-10

We report the electrical properties of rubidium-incorporated methylammonium lead iodide ((Rb xMA 1-x)PbI 3) films and the photovoltaic performance of (Rb xMA 1-x)PbI 3 film-based p-i-n-type perovskite solar cells (PSCs). The incorporation of a small amount of Rb + (x = 0.05) increases both the open circuit voltage (V oc) and the short circuit photocurrent density (J sc) of the PSCs, leading to an improved power conversion efficiency (PCE). However, a high fraction of Rb + incorporation (x = 0.1 and 0.2) decreases the J sc and thus the PCE, which is attributed to the phase segregation of the singlemore » tetragonal perovskite phase to a MA-rich tetragonal perovskite phase and a RbPbI 3 orthorhombic phase at high Rb fractions. Conductive atomic force microscopic and admittance spectroscopic analyses reveal that the single-phase (Rb 0.05MA 0.95)PbI 3 film has a high electrical conductivity because of a reduced deep-level trap density. We also found that Rb substitution enhances the diode characteristics of the PSC, as evidenced by the reduced reverse saturation current (J 0). The optimized (Rb xMA 1-x)PbI 3 PSCs exhibited a PCE of 18.8% with negligible hysteresis in the photocurrent-voltage curve. The results from this work enhance the understanding of the effect of Rb incorporation into organic-inorganic hybrid halide perovskites and enable the exploration of Rb-incorporated mixed perovskites for various applications, such as solar cells, photodetectors, and light-emitting diodes.« less

Effect of Rubidium Incorporation on the Structural, Electrical, and Photovoltaic Properties of Methylammonium Lead Iodide-Based Perovskite Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Ik Jae; Seo, Seongrok; Park, Min Ah

We report the electrical properties of rubidium-incorporated methylammonium lead iodide ((Rb xMA 1-x)PbI 3) films and the photovoltaic performance of (Rb xMA 1-x)PbI 3 film-based p-i-n-type perovskite solar cells (PSCs). The incorporation of a small amount of Rb + (x = 0.05) increases both the open circuit voltage (V oc) and the short circuit photocurrent density (J sc) of the PSCs, leading to an improved power conversion efficiency (PCE). However, a high fraction of Rb + incorporation (x = 0.1 and 0.2) decreases the J sc and thus the PCE, which is attributed to the phase segregation of the singlemore » tetragonal perovskite phase to a MA-rich tetragonal perovskite phase and a RbPbI 3 orthorhombic phase at high Rb fractions. Conductive atomic force microscopic and admittance spectroscopic analyses reveal that the single-phase (Rb 0.05MA 0.95)PbI 3 film has a high electrical conductivity because of a reduced deep-level trap density. We also found that Rb substitution enhances the diode characteristics of the PSC, as evidenced by the reduced reverse saturation current (J 0). The optimized (Rb xMA 1-x)PbI 3 PSCs exhibited a PCE of 18.8% with negligible hysteresis in the photocurrent-voltage curve. The results from this work enhance the understanding of the effect of Rb incorporation into organic-inorganic hybrid halide perovskites and enable the exploration of Rb-incorporated mixed perovskites for various applications, such as solar cells, photodetectors, and light-emitting diodes.« less

Geophysical Investigation Along the Great Miami River From New Miami to Charles M. Bolton Well Field, Cincinnati, Ohio

USGS Publications Warehouse

Sheets, R.A.; Dumouchelle, D.H.

2009-01-01

Three geophysical profiling methods were tested to help characterize subsurface materials at selected transects along the Great Miami River, in southwestern Ohio. The profiling methods used were continuous seismic profiling (CSP), continuous resistivity profiling (CRP), and continuous electromagnetic profiling (CEP). Data were collected with global positioning systems to spatially locate the data along the river. The depth and flow conditions of the Great Miami River limited the amount and quality of data that could be collected with the CSP and CRP methods. Data from the CSP were generally poor because shallow reflections (less than 5 meters) were mostly obscured by strong multiple reflections and deep reflections (greater than 5 meters) were sparse. However, modeling of CRP data indicated broad changes in subbottom geology, primarily below about 3 to 5 meters. Details for shallow electrical conductivity (resistivity) (less than 3 meters) were limited because of the 5-meter electrode spacing used for the surveys. For future studies of this type, a cable with 3-meter electrode spacing (or perhaps even 1-meter spacing) might best be used in similar environments to determine shallow electrical properties of the stream-bottom materials. CEP data were collected along the entire reach of the Great Miami River. The CRP and CEP data did not correlate well, but the CRP electrode spacing probably limited the correlation. Middle-frequency (3,510 hertz) and high-frequency (15,030 hertz) CEP data were correlated to water depth. Low-frequency (750 hertz) CEP data indicate shallow (less than 5-meter) changes in electrical conductivity. Given the variability in depth and flow conditions on a river such as the Great Miami, the CEP method worked better than either the CSP or CRP methods.

A computational model to compare different investment scenarios for mini-stereotactic frame approach to deep brain stimulation surgery.

PubMed

Lanotte, M; Cavallo, M; Franzini, A; Grifi, M; Marchese, E; Pantaleoni, M; Piacentino, M; Servello, D

2010-09-01

Deep brain stimulation (DBS) alleviates symptoms of many neurological disorders by applying electrical impulses to the brain by means of implanted electrodes, generally put in place using a conventional stereotactic frame. A new image guided disposable mini-stereotactic system has been designed to help shorten and simplify DBS procedures when compared to standard stereotaxy. A small number of studies have been conducted which demonstrate localization accuracies of the system similar to those achievable by the conventional frame. However no data are available to date on the economic impact of this new frame. The aim of this paper was to develop a computational model to evaluate the investment required to introduce the image guided mini-stereotactic technology for stereotactic DBS neurosurgery. A standard DBS patient care pathway was developed and related costs were analyzed. A differential analysis was conducted to capture the impact of introducing the image guided system on the procedure workflow. The analysis was carried out in five Italian neurosurgical centers. A computational model was developed to estimate upfront investments and surgery costs leading to a definition of the best financial option to introduce the new frame. Investments may vary from Euro 1.900 (purchasing of Image Guided [IG] mini-stereotactic frame only) to Euro 158.000.000. Moreover the model demonstrates how the introduction of the IG mini-stereotactic frame doesn't substantially affect the DBS procedure costs.

Characterization of irradiation induced deep and shallow impurities

NASA Astrophysics Data System (ADS)

Treberspurg, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Krammer, Manfred; Valentan, Manfred

2013-12-01

Silicon Detectors close to the interaction point of the High Luminosity Large Hardron Collider (HL-LHC) have to withstand a harsh irradiation environment. In order to evaluate the behaviour of shallow and deep defects, induced by neutron irradiation, spreading resistance resistivity measurements and capacitance voltage measurements have been performed. These measurements, deliver information about the profile of shallow impurities after irradiation as well as indications of deep defects in the Space Charge Region (SCR) and the Electrical Neutral Bulk (ENB). By considering the theoretical background of the measurement both kinds of defects can be investigated independently from each other.

Electrical contact arrangement for a coating process

DOEpatents

Kabagambe, Benjamin; McCamy, James W; Boyd, Donald W

2013-09-17

A protective coating is applied to the electrically conductive surface of a reflective coating of a solar mirror by biasing a conductive member having a layer of a malleable electrically conductive material, e.g. a paste, against a portion of the conductive surface while moving an electrodepositable coating composition over the conductive surface. The moving of the electrodepositable coating composition over the conductive surface includes moving the solar mirror through a flow curtain of the electrodepositable coating composition and submerging the solar mirror in a pool of the electrodepositable coating composition. The use of the layer of a malleable electrically conductive material between the conductive member and the conductive surface compensates for irregularities in the conductive surface being contacted during the coating process thereby reducing the current density at the electrical contact area.

The effects of neuromuscular electrical stimulation at different frequencies on the activations of deep abdominal stabilizing muscles.

PubMed

Cho, Hee Kyung; Jung, Gil Su; Kim, Eun Hyuk; Cho, Yun Woo; Kim, Sang Woo; Ahn, Sang Ho

2016-01-01

Low back pain is associated with transversus abdominis (TrA) dysfunction. Recently, it was proposed that Neuromuscular Electrical Stimulation (NMES) could be used to stimulate deep abdominal muscle contractions and improve lumbopelvic stability. The purpose of this study was to determine the optimal stimulation frequency required during NMES for the activation of deep abdominal muscles. Twenty healthy volunteers between the ages of 24 and 32 were included. The portable research-stimulator was applied using a 10 second contraction time, and a 10 second resting time at 20 Hz, 50 Hz, and 80 Hz. Changes in muscle thicknesses were determined for the TrA, obliquus internus (OI), and obliquus externus (OE) by real time ultrasound imaging. Significant thickness increases in the TrA, OI, and OE were observed during NMES versus the resting state (p < 0.05). Of the frequencies examined, 50 Hz NMES produced the greatest increase in TrA thickness (1.33 fold as compared with 1.22 fold at 20 Hz and 1.21 fold at 80 Hz) (p < 0.05). Our results indicate that NMES can preferentially stimulate contractions in deep abdominal stabilizing muscles. Most importantly, 50 Hz NMES produced greater muscle thickness increases than 20 or 80 Hz.

Anisotropy of synthetic quartz electrical conductivity at high pressure and temperature

NASA Astrophysics Data System (ADS)

Wang, Duojun; Li, Heping; Yi, Li; Matsuzaki, Takuya; Yoshino, Takashi

2010-09-01

AC measurements of the electrical conductivity of synthetic quartz along various orientations were made between 0.1 and 1 MHz, at ˜855˜1601 K and at 1.0 GPa. In addition, the electrical conductivity of quartz along the c axis has been studied at 1.0-3.0 GPa. The impedance arcs representing bulk conductivity occur in the frequency range of 103-106 Hz, and the electrical responses of the interface between the sample and the electrode occur in the 0.1˜103 Hz range. The pressure has a weak effect on the electrical conductivity. The electrical conductivity experiences no abrupt change near the α - β phase transition point. The electrical conductivity of quartz is highly anisotropic; the electrical conductivity along the c axis is strongest and several orders of magnitude larger than in other directions. The activation enthalpies along various orientations are determined to be 0.6 and 1.2 eV orders of magnitude, respectively. The interpretation of the former is based on the contribution of alkali ions, while the latter effect is attributed to additional unassociated aluminum ions. Comparison of determined anisotropic conductivity of quartz determined with those from field geophysical models shows that the quartz may potentially provide explanations for the behavior of electrical conductivity of anisotropy in the crust that are inferred from the transverse magnetic mode.

High electric field conduction in low-alkali boroaluminosilicate glass

NASA Astrophysics Data System (ADS)

Dash, Priyanka; Yuan, Mengxue; Gao, Jun; Furman, Eugene; Lanagan, Michael T.

2018-02-01

Electrical conduction in silica-based glasses under a low electric field is dominated by high mobility ions such as sodium, and there is a transition from ionic transport to electronic transport as the electric field exceeds 108 V/m at low temperatures. Electrical conduction under a high electric field was investigated in thin low-alkali boroaluminosilicate glass samples, showing nonlinear conduction with the current density scaling approximately with E1/2, where E is the electric field. In addition, thermally stimulated depolarization current (TSDC) characterization was carried out on room-temperature electrically poled glass samples, and an anomalous discharging current flowing in the same direction as the charging current was observed. High electric field conduction and TSDC results led to the conclusion that Poole-Frenkel based electronic transport occurs in the mobile-cation-depleted region adjacent to the anode, and accounts for the observed anomalous current.

Capillary zone electrophoresis-mass spectrometer interface

DOEpatents

D'Silva, Arthur

1996-08-06

A device for providing equal electrical potential between two loci unconnected by solid or liquid electrical conducts is provided. The device comprises a first electrical conducting terminal, a second electrical conducting terminal connected to the first terminal by a rigid dielectric structure, and an electrically conducting gas contacting the first and second terminals. This device is particularly suitable for application in the electrospray ionization interface between a capillary zone electrophoresis apparatus and a mass spectrometer.

An electrical method for the measurement of the thermal and electrical conductivity of reduced graphene oxide nanostructures.

PubMed

Schwamb, Timo; Burg, Brian R; Schirmer, Niklas C; Poulikakos, Dimos

2009-10-07

This paper introduces an electrical four-point measurement method enabling thermal and electrical conductivity measurements of nanoscale materials. The method was applied to determine the thermal and electrical conductivity of reduced graphene oxide flakes. The dielectrophoretically deposited samples exhibited thermal conductivities in the range of 0.14-2.87 W m(-1) K(-1) and electrical conductivities in the range of 6.2 x 10(2)-6.2 x 10(3) Omega(-1) m(-1). The measured properties of each flake were found to be dependent on the duration of the thermal reduction and are in this sense controllable.

p-type doping by platinum diffusion in low phosphorus doped silicon

NASA Astrophysics Data System (ADS)

Ventura, L.; Pichaud, B.; Vervisch, W.; Lanois, F.

2003-07-01

In this work we show that the cooling rate following a platinum diffusion strongly influences the electrical conductivity in weakly phosphorus doped silicon. Diffusions were performed at the temperature of 910 °C in the range of 8 32 hours in 0.6, 30, and 60 Ωrm cm phosphorus doped silicon samples. Spreading resistance profile analyses clearly show an n-type to p-type conversion under the surface when samples are cooled slowly. On the other hand, a compensation of the phosphorus donors can only be observed when samples are quenched. One Pt related acceptor deep level at 0.43 eV from the valence band is assumed to be at the origin of the type conversion mechanism. Its concentration increases by lowering the applied cooling rate. A complex formation with fast species such as interstitial Pt atoms or intrinsic point defects is expected. In 0.6 Ωrm cm phosphorus doped silicon, no acceptor deep level in the lower band gap is detected by DLTS measurement. This removes the opportunity of a pairing between phosphorus and platinum and suggests the possibility of a Fermi level controlled complex formation.

Assessing the direct effects of deep brain stimulation using embedded axon models

NASA Astrophysics Data System (ADS)

Sotiropoulos, Stamatios N.; Steinmetz, Peter N.

2007-06-01

To better understand the spatial extent of the direct effects of deep brain stimulation (DBS) on neurons, we implemented a geometrically realistic finite element electrical model incorporating anisotropic and inhomogenous conductivities. The model included the subthalamic nucleus (STN), substantia nigra (SN), zona incerta (ZI), fields of Forel H2 (FF), internal capsule (IC) and Medtronic 3387/3389 electrode. To quantify the effects of stimulation, we extended previous studies by using multi-compartment axon models with geometry and orientation consistent with anatomical features of the brain regions of interest. Simulation of axonal firing produced a map of relative changes in axonal activation. Voltage-controlled stimulation, with clinically typical parameters at the dorso-lateral STN, caused axon activation up to 4 mm from the target. This activation occurred within the FF, IC, SN and ZI with current intensities close to the average injected during DBS (3 mA). A sensitivity analysis of model parameters (fiber size, fiber orientation, degree of inhomogeneity, degree of anisotropy, electrode configuration) revealed that the FF and IC were consistently activated. Direct activation of axons outside the STN suggests that other brain regions may be involved in the beneficial effects of DBS when treating Parkinsonian symptoms.

Paradoxical augmented relapse in alcohol-dependent rats during deep-brain stimulation in the nucleus accumbens

PubMed Central

Hadar, R; Vengeliene, V; Barroeta Hlusicke, E; Canals, S; Noori, H R; Wieske, F; Rummel, J; Harnack, D; Heinz, A; Spanagel, R; Winter, C

2016-01-01

Case reports indicate that deep-brain stimulation in the nucleus accumbens may be beneficial to alcohol-dependent patients. The lack of clinical trials and our limited knowledge of deep-brain stimulation call for translational experiments to validate these reports. To mimic the human situation, we used a chronic-continuous brain-stimulation paradigm targeting the nucleus accumbens and other brain sites in alcohol-dependent rats. To determine the network effects of deep-brain stimulation in alcohol-dependent rats, we combined electrical stimulation of the nucleus accumbens with functional magnetic resonance imaging (fMRI), and studied neurotransmitter levels in nucleus accumbens-stimulated versus sham-stimulated rats. Surprisingly, we report here that electrical stimulation of the nucleus accumbens led to augmented relapse behavior in alcohol-dependent rats. Our associated fMRI data revealed some activated areas, including the medial prefrontal cortex and caudate putamen. However, when we applied stimulation to these areas, relapse behavior was not affected, confirming that the nucleus accumbens is critical for generating this paradoxical effect. Neurochemical analysis of the major activated brain sites of the network revealed that the effect of stimulation may depend on accumbal dopamine levels. This was supported by the finding that brain-stimulation-treated rats exhibited augmented alcohol-induced dopamine release compared with sham-stimulated animals. Our data suggest that deep-brain stimulation in the nucleus accumbens enhances alcohol-liking probably via augmented dopamine release and can thereby promote relapse. PMID:27327255

Development of a new method for the noninvasive measurement of deep body temperature without a heater.

PubMed

Kitamura, Kei-Ichiro; Zhu, Xin; Chen, Wenxi; Nemoto, Tetsu

2010-01-01

The conventional zero-heat-flow thermometer, which measures the deep body temperature from the skin surface, is widely used at present. However, this thermometer requires considerable electricity to power the electric heater that compensates for heat loss from the probe; thus, AC power is indispensable for its use. Therefore, this conventional thermometer is inconvenient for unconstrained monitoring. We have developed a new dual-heat-flux method that can measure the deep body temperature from the skin surface without a heater. Our method is convenient for unconstrained and long-term measurement because the instrument is driven by a battery and its design promotes energy conservation. Its probe consists of dual-heat-flow channels with different thermal resistances, and each heat-flow-channel has a pair of IC sensors attached on its top and bottom. The average deep body temperature measurements taken using both the dual-heat-flux and then the zero-heat-flow thermometers from the foreheads of 17 healthy subjects were 37.08 degrees C and 37.02 degrees C, respectively. In addition, the correlation coefficient between the values obtained by the 2 methods was 0.970 (p<0.001). These results show that our method can be used for monitoring the deep body temperature as accurately as the conventional method, and it overcomes the disadvantage of the necessity of AC power supply. (c) 2009 IPEM. Published by Elsevier Ltd. All rights reserved.

Deep learning based state recognition of substation switches

NASA Astrophysics Data System (ADS)

Wang, Jin

2018-06-01

Different from the traditional method which recognize the state of substation switches based on the running rules of electrical power system, this work proposes a novel convolutional neuron network-based state recognition approach of substation switches. Inspired by the theory of transfer learning, we first establish a convolutional neuron network model trained on the large-scale image set ILSVRC2012, then the restricted Boltzmann machine is employed to replace the full connected layer of the convolutional neuron network and trained on our small image dataset of 110kV substation switches to get a stronger model. Experiments conducted on our image dataset of 110kV substation switches show that, the proposed approach can be applicable to the substation to reduce the running cost and implement the real unattended operation.

High gain photoconductive semiconductor switch having tailored doping profile zones

DOEpatents

Baca, Albert G.; Loubriel, Guillermo M.; Mar, Alan; Zutavern, Fred J; Hjalmarson, Harold P.; Allerman, Andrew A.; Zipperian, Thomas E.; O'Malley, Martin W.; Helgeson, Wesley D.; Denison, Gary J.; Brown, Darwin J.; Sullivan, Charles T.; Hou, Hong Q.

2001-01-01

A photoconductive semiconductor switch with tailored doping profile zones beneath and extending laterally from the electrical contacts to the device. The zones are of sufficient depth and lateral extent to isolate the contacts from damage caused by the high current filaments that are created in the device when it is turned on. The zones may be formed by etching depressions into the substrate, then conducting epitaxial regrowth in the depressions with material of the desired doping profile. They may be formed by surface epitaxy. They may also be formed by deep diffusion processes. The zones act to reduce the energy density at the contacts by suppressing collective impact ionization and formation of filaments near the contact and by reducing current intensity at the contact through enhanced current spreading within the zones.

Anisotropic Babinet-Invertible Metasurfaces to Realize Transmission-Reflection Switching for Orthogonal Polarizations of Light

NASA Astrophysics Data System (ADS)

Nakata, Yosuke; Urade, Yoshiro; Okimura, Kunio; Nakanishi, Toshihiro; Miyamaru, Fumiaki; Takeda, Mitsuo Wada; Kitano, Masao

2016-10-01

The electromagnetic properties of an extremely thin metallic checkerboard drastically change from resonant reflection (transmission) to resonant transmission (reflection) when the local electrical conductivity at the interconnection points of the checkerboard is switched. To date, such critical transitions of metasurfaces have been applied only when they have fourfold rotational symmetry, and their application to polarization control, which requires anisotropy, has been unexplored. To overcome this applicability limitation and open up alternative pathways for dynamic deep-subwavelength polarization control by utilizing critical transitions of checkerboardlike metasurfaces, we introduce a universal class of anisotropic Babinet-invertible metasurfaces enabling transmission-reflection switching for each orthogonally polarized wave. As an application of anisotropic Babinet-invertible metasurfaces, we experimentally realize a reconfigurable terahertz polarizer whose transmitting axis can be dynamically rotated by 90°.

Analyzing the tradeoff between electrical complexity and accuracy in patient-specific computational models of deep brain stimulation.

PubMed

Howell, Bryan; McIntyre, Cameron C

2016-06-01

Deep brain stimulation (DBS) is an adjunctive therapy that is effective in treating movement disorders and shows promise for treating psychiatric disorders. Computational models of DBS have begun to be utilized as tools to optimize the therapy. Despite advancements in the anatomical accuracy of these models, there is still uncertainty as to what level of electrical complexity is adequate for modeling the electric field in the brain and the subsequent neural response to the stimulation. We used magnetic resonance images to create an image-based computational model of subthalamic DBS. The complexity of the volume conductor model was increased by incrementally including heterogeneity, anisotropy, and dielectric dispersion in the electrical properties of the brain. We quantified changes in the load of the electrode, the electric potential distribution, and stimulation thresholds of descending corticofugal (DCF) axon models. Incorporation of heterogeneity altered the electric potentials and subsequent stimulation thresholds, but to a lesser degree than incorporation of anisotropy. Additionally, the results were sensitive to the choice of method for defining anisotropy, with stimulation thresholds of DCF axons changing by as much as 190%. Typical approaches for defining anisotropy underestimate the expected load of the stimulation electrode, which led to underestimation of the extent of stimulation. More accurate predictions of the electrode load were achieved with alternative approaches for defining anisotropy. The effects of dielectric dispersion were small compared to the effects of heterogeneity and anisotropy. The results of this study help delineate the level of detail that is required to accurately model electric fields generated by DBS electrodes.

Analyzing the tradeoff between electrical complexity and accuracy in patient-specific computational models of deep brain stimulation

NASA Astrophysics Data System (ADS)

Howell, Bryan; McIntyre, Cameron C.

2016-06-01

Objective. Deep brain stimulation (DBS) is an adjunctive therapy that is effective in treating movement disorders and shows promise for treating psychiatric disorders. Computational models of DBS have begun to be utilized as tools to optimize the therapy. Despite advancements in the anatomical accuracy of these models, there is still uncertainty as to what level of electrical complexity is adequate for modeling the electric field in the brain and the subsequent neural response to the stimulation. Approach. We used magnetic resonance images to create an image-based computational model of subthalamic DBS. The complexity of the volume conductor model was increased by incrementally including heterogeneity, anisotropy, and dielectric dispersion in the electrical properties of the brain. We quantified changes in the load of the electrode, the electric potential distribution, and stimulation thresholds of descending corticofugal (DCF) axon models. Main results. Incorporation of heterogeneity altered the electric potentials and subsequent stimulation thresholds, but to a lesser degree than incorporation of anisotropy. Additionally, the results were sensitive to the choice of method for defining anisotropy, with stimulation thresholds of DCF axons changing by as much as 190%. Typical approaches for defining anisotropy underestimate the expected load of the stimulation electrode, which led to underestimation of the extent of stimulation. More accurate predictions of the electrode load were achieved with alternative approaches for defining anisotropy. The effects of dielectric dispersion were small compared to the effects of heterogeneity and anisotropy. Significance. The results of this study help delineate the level of detail that is required to accurately model electric fields generated by DBS electrodes.

Large eddy simulation of the tidal power plant deep green using the actuator line method

NASA Astrophysics Data System (ADS)

Fredriksson, S. T.; Broström, G.; Jansson, M.; Nilsson, H.; Bergqvist, B.

2017-12-01

Tidal energy has the potential to provide a substantial part of the sustainable electric power generation. The tidal power plant developed by Minesto, called Deep Green, is a novel technology using a ‘flying’ kite with an attached turbine, moving at a speed several times higher than the mean flow. Multiple Deep Green power plants will eventually form arrays, which require knowledge of both flow interactions between individual devices and how the array influences the surrounding environment. The present study uses large eddy simulations (LES) and an actuator line model (ALM) to analyze the oscillating turbulent boundary layer flow in tidal currents without and with a Deep Green power plant. We present the modeling technique and preliminary results so far.

Electron emission from deep level defects EL2 and EL6 in semi-insulating GaAs observed by positron drift velocity transient measurements

NASA Astrophysics Data System (ADS)

Tsia, J. M.; Ling, C. C.; Beling, C. D.; Fung, S.

2002-09-01

A plus-or-minus100 V square wave applied to a Au/semi-insulating SI-GaAs interface was used to bring about electron emission from and capture into deep level defects in the region adjacent to the interface. The electric field transient resulting from deep level emission was studied by monitoring the positron drift velocity in the region. A deep level transient spectrum was obtained by computing the trap emission rate as a function of temperature and two peaks corresponding to EL2 (Ea=0.81plus-or-minus0.15 eV) and EL6 (Ea=0.30plus-or-minus0.12 eV) have been identified.

Electrical condition monitoring method for polymers

DOEpatents

Watkins, Jr., Kenneth S.; Morris, Shelby J [Hampton, VA; Masakowski, Daniel D [Worcester, MA; Wong, Ching Ping [Duluth, GA; Luo, Shijian [Boise, ID

2008-08-19

An electrical condition monitoring method utilizes measurement of electrical resistivity of an age sensor made of a conductive matrix or composite disposed in a polymeric structure such as an electrical cable. The conductive matrix comprises a base polymer and conductive filler. The method includes communicating the resistivity to a measuring instrument and correlating resistivity of the conductive matrix of the polymeric structure with resistivity of an accelerated-aged conductive composite.

Carbon-Nanotube Conductive Layers for Thin-Film Solar Cells

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.

2005-01-01

Thin, transparent layers comprising mats of carbon nanotubes have been proposed for providing lateral (that is, inplane) electrical conductivities for collecting electric currents from the front surfaces of the emitter layers of thin-film solar photovoltaic cells. Traditionally, thin, semitransparent films of other electrically conductive materials (usually, indium tin oxide, zinc oxide, or cadmium sulfide) have been used for this purpose. As in the cases of the traditional semitransparent conductive films, the currents collected by the nanotube layers would, in turn, be further collected by front metal contact stripes. Depending on details of a specific solar-cell design, the layer of carbon nanotubes would be deposited in addition to, or instead of, a semitransparent layer of one of these traditional conductive materials (see figure). The proposal is expected to afford the following advantages: The electrical conductivity of the carbon- nanotube layer would exceed that of the corresponding semitransparent layer of traditional electrically conductive material. The greater electrical conductivity of the carbon-nanotube layer would make it possible to retain adequate lateral electrical conductivity while reducing the thickness of, or eliminating entirely, the traditional semitransparent conductive layer. As a consequence of thinning or elimination of the traditional semitransparent conductive layer, less light would be absorbed, so that more of the incident light would be available for photovoltaic conversion. The greater electrical conductivity of the carbon-nanotube layer would make it possible to increase the distance between front metal contact stripes, in addition to (or instead of) thinning or eliminating the layer of traditional semitransparent conductive material. Consequently, the fraction of solar-cell area shadowed by front metal contact stripes would be reduced again, making more of the incident light available for photovoltaic conversion. The electrical conductivities of individual carbon nanotubes can be so high that the mat of carbon nanotubes could be made sparse enough to be adequately transparent while affording adequate lateral electrical conductivity of the mat as a whole. The thickness of the nanotube layer would be chosen so that the layer would contribute significant lateral electrical conductivity, yet would be as nearly transparent as possible to incident light. A typical thickness for satisfying these competing requirements is expected to lie between 50 and 100 nm. The optimum thickness must be calculated by comparing the lateral electrical conductivity, the distance between front metal stripes, and the amount of light lost by absorption in the nanotube layer.

Electrical conductivity of electrolytes applicable to natural waters from 0 to 100 degrees C

USGS Publications Warehouse

McCleskey, R. Blaine

2011-01-01

The electrical conductivities of 34 electrolyte solutions found in natural waters ranging from (10-4 to 1) mol•kg-1 in concentration and from (5 to 90) °C have been determined. High-quality electrical conductivity data for numerous electrolytes exist in the scientific literature, but the data do not span the concentration or temperature ranges of many electrolytes in natural waters. Methods for calculating the electrical conductivities of natural waters have incorporated these data from the literature, and as a result these methods cannot be used to reliably calculate the electrical conductivity over a large enough range of temperature and concentration. For the single-electrolyte solutions, empirical equations were developed that relate electrical conductivity to temperature and molality. For the 942 molar conductivity determinations for single electrolytes from this study, the mean relative difference between the calculated and measured values was 0.1 %. The calculated molar conductivity was compared to literature data, and the mean relative difference for 1978 measurements was 0.2 %. These data provide an improved basis for calculating electrical conductivity for most natural waters.

Hydroxyapatite Nanowire-Based All-Weather Flexible Electrically Conductive Paper with Superhydrophobic and Flame-Retardant Properties.

PubMed

Chen, Fei-Fei; Zhu, Ying-Jie; Xiong, Zhi-Chao; Dong, Li-Ying; Chen, Feng; Lu, Bing-Qiang; Yang, Ri-Long

2017-11-15

How to survive under various harsh working conditions is a key challenge for flexible electronic devices because their performances are always susceptible to environments. Herein, we demonstrate the novel design and fabrication of a new kind of the all-weather flexible electrically conductive paper based on ultralong hydroxyapatite nanowires (HNs) with unique combination of the superhydrophobic surface, electrothermal effect, and flame retardancy. The superhydrophobic surface with water repellency stabilizes the electrically conductive performance of the paper in water. For example, the electrical current through the superhydrophobic paper onto which water droplets are deposited shows a little change (0.38%), and the electrical performance is steady as well even when the paper is immersed in water for 120 s (just 3.65% change). In addition, the intrinsic electrothermal effect of the electrically conductive paper can efficiently heat the paper to reach a high temperature, for example, 224.25 °C, within 10 s. The synergistic effect between the electrothermal effect and superhydrophobic surface accelerates the melting and removal of ice on the heated electrically conductive paper. Deicing efficiency of the heated superhydrophobic electrically conductive paper is ∼4.5 times that of the unheated superhydrophobic electrically conductive paper and ∼10.4 times that of the heated superhydrophilic paper. More importantly, benefiting from fire-resistant ultralong HNs, thermally stable Ketjen black, and Si-O backbone of poly(dimethylsiloxane), we demonstrate the stable and continuous service of the as-prepared electrically conductive paper in the flame for as long as 7 min. The electrical performance of the electrically conductive paper after flame treatment can maintain as high as 90.60% of the original value. The rational design of the electrically conductive paper with suitable building materials and structure demonstrated here will give an inspiration for the development of new kinds of all-weather flexible electronic devices that can work under harsh conditions.

Evaluation of Soft Tissue Sarcoma Tumors Electrical Conductivity Anisotropy Using Diffusion Tensor Imaging for Numerical Modeling on Electroporation.

PubMed

Ghazikhanlou-Sani, K; Firoozabadi, S M P; Agha-Ghazvini, L; Mahmoodzadeh, H

2016-06-01

There is many ways to assessing the electrical conductivity anisotropy of a tumor. Applying the values of tissue electrical conductivity anisotropy is crucial in numerical modeling of the electric and thermal field distribution in electroporation treatments. This study aims to calculate the tissues electrical conductivity anisotropy in patients with sarcoma tumors using diffusion tensor imaging technique. A total of 3 subjects were involved in this study. All of patients had clinically apparent sarcoma tumors at the extremities. The T1, T2 and DTI images were performed using a 3-Tesla multi-coil, multi-channel MRI system. The fractional anisotropy (FA) maps were performed using the FSL (FMRI software library) software regarding the DTI images. The 3D matrix of the FA maps of each area (tumor, normal soft tissue and bone/s) was reconstructed and the anisotropy matrix was calculated regarding to the FA values. The mean FA values in direction of main axis in sarcoma tumors were ranged between 0.475-0.690.  With assumption of isotropy of the electrical conductivity, the FA value of electrical conductivity at each X, Y and Z coordinate axes would be equal to 0.577. The gathered results showed that there is a mean error band of 20% in electrical conductivity, if the electrical conductivity anisotropy not concluded at the calculations. The comparison of FA values showed that there is a significant statistical difference between the mean FA value of tumor and normal soft tissues (P<0.05). DTI is a feasible technique for the assessment of electrical conductivity anisotropy of tissues.  It is crucial to quantify the electrical conductivity anisotropy data of tissues for numerical modeling of electroporation treatments.

High seismic attenuation at a mid-ocean ridge reveals the distribution of deep melt.

PubMed

Eilon, Zachary C; Abers, Geoffrey A

2017-05-01

At most mid-ocean ridges, a wide region of decompression melting must be reconciled with a narrow neovolcanic zone and the establishment of full oceanic crustal thickness close to the rift axis. Two competing paradigms have been proposed to explain melt focusing: narrow mantle upwelling due to dynamic effects related to in situ melt or wide mantle upwelling with lateral melt transport in inclined channels. Measurements of seismic attenuation provide a tool for identifying and characterizing the presence of melt and thermal heterogeneity in the upper mantle. We use a unique data set of teleseismic body waves recorded on the Cascadia Initiative's Amphibious Array to simultaneously measure seismic attenuation and velocity across an entire oceanic microplate. We observe maximal differential attenuation and the largest delays ([Formula: see text] s and δ T S ~ 2 s) in a narrow zone <50 km from the Juan de Fuca and Gorda ridge axes, with values that are not consistent with laboratory estimates of temperature or water effects. The implied seismic quality factor ( Q s ≤ 25) is among the lowest observed worldwide. Models harnessing experimentally derived anelastic scaling relationships require a 150-km-deep subridge region containing up to 2% in situ melt. The low viscosity and low density associated with this deep, narrow melt column provide the conditions for dynamic mantle upwelling, explaining a suite of geophysical observations at ridges, including electrical conductivity and shear velocity anomalies.

Grain boundary dominated electrical conductivity in ultrananocrystalline diamond

NASA Astrophysics Data System (ADS)

Wiora, Neda; Mertens, Michael; Brühne, Kai; Fecht, Hans-Jörg; Tran, Ich C.; Willey, Trevor; van Buuren, Anthony; Biener, Jürgen; Lee, Jun-Sik

2017-10-01

N-type electrically conductive ultrananocrystalline diamond (UNCD) films were deposited using the hot filament chemical vapor deposition technique with a gas mixture of H2, CH4 and NH3. Depending on the deposition temperature and ammonia feed gas concentration, which serves as a nitrogen source, room temperature electrical conductivities in the order of 10-2 to 5 × 101 S/cm and activation energies in the meV range were achieved. In order to understand the origin of the enhanced electrical conductivity and clarify the role of ammonia addition to the process gas, a set of UNCD films was grown by systematically varying the ammonia gas phase concentration. These samples were analyzed with respect to their morphology and electrical properties as well as their carbon and nitrogen bonding environments. Temperature dependent electrical conductivity measurements (300-1200 K) show that the electrical conductivity of the samples increases with temperature. The near edge x-ray absorption fine structure measurements reveal that the electrical conductivity of the UNCD films does not correlate directly with ammonia addition, but depends on the total amount of sp2 bonded carbon in the deposited films.

Effect of the mechanical deformation on the electrical properties of the polymer/CNT fiber

NASA Astrophysics Data System (ADS)

Cho, Hyun Woo; Sung, Bong June; Nano-Bio Computational Chemistry Laboratory Team

2014-03-01

We elucidate the effect of the mechanical deformation on the electrical properties of the polymer/CNT fiber. The conductive polymer fiber has drawn a great attention for its potential application to a stretchable electronics such as wearable devices and artificial muscles, etc. However, the electrical conductivity of the polymer-based stretchable electronics decreases significantly during the deformation, which may limit the applicability of the polymer/CNT fiber for the stretchable electronics. Moreover, its physical origin for the decrease in electrical conductivity has not been explained clearly. In this work, we employ a coarse-grained model for the polymer/CNT fiber, and we calculate the electric conductivity using global tunneling network (GTN) model. We show that the electric conductivity decreases during the elongation of the polymer/CNT fiber. We also find using critical path approximation (CPA) that the structure of the electrical network of the CNTs changes collectively during the elongation of the fiber, which is strongly responsible for the reduction of the electrical conductivity of the polymer/CNT fiber.

Hot wire needle probe for thermal conductivity detection

DOEpatents

Condie, Keith Glenn; Rempe, Joy Lynn; Knudson, Darrell lee; Daw, Joshua Earl; Wilkins, Steven Curtis; Fox, Brandon S.; Heng, Ban

2015-11-10

An apparatus comprising a needle probe comprising a sheath, a heating element, a temperature sensor, and electrical insulation that allows thermal conductivity to be measured in extreme environments, such as in high-temperature irradiation testing. The heating element is contained within the sheath and is electrically conductive. In an embodiment, the heating element is a wire capable of being joule heated when an electrical current is applied. The temperature sensor is contained within the sheath, electrically insulated from the heating element and the sheath. The electrical insulation electrically insulates the sheath, heating element and temperature sensor. The electrical insulation fills the sheath having electrical resistance capable of preventing electrical conduction between the sheath, heating element, and temperature sensor. The control system is connected to the heating element and the temperature sensor.

Step-off, vertical electromagnetic responses of a deep resistivity layer buried in marine sediments

NASA Astrophysics Data System (ADS)

Jang, Hangilro; Jang, Hannuree; Lee, Ki Ha; Kim, Hee Joon

2013-04-01

A frequency-domain, marine controlled-source electromagnetic (CSEM) method has been applied successfully in deep water areas for detecting hydrocarbon (HC) reservoirs. However, a typical technique with horizontal transmitters and receivers requires large source-receiver separations with respect to the target depth. A time-domain EM system with vertical transmitters and receivers can be an alternative because vertical electric fields are sensitive to deep resistive layers. In this paper, a time-domain modelling code, with multiple source and receiver dipoles that are finite in length, has been written to investigate transient EM problems. With the use of this code, we calculate step-off responses for one-dimensional HC reservoir models. Although the vertical electric field has much smaller amplitude of signal than the horizontal field, vertical currents resulting from a vertical transmitter are sensitive to resistive layers. The modelling shows a significant difference between step-off responses of HC- and water-filled reservoirs, and the contrast can be recognized at late times at relatively short offsets. A maximum contrast occurs at more than 4 s, being delayed with the depth of the HC layer.

Deep brain stimulation mechanisms: beyond the concept of local functional inhibition.

PubMed

Deniau, Jean-Michel; Degos, Bertrand; Bosch, Clémentine; Maurice, Nicolas

2010-10-01

Deep brain electrical stimulation has become a recognized therapy in the treatment of a variety of motor disorders and has potentially promising applications in a wide range of neurological diseases including neuropsychiatry. Behavioural observation that electrical high-frequency stimulation of a given brain area induces an effect similar to a lesion suggested a mechanism of functional inhibition. In vitro and in vivo experiments as well as per operative recordings in patients have revealed a variety of effects involving local changes of neuronal excitability as well as widespread effects throughout the connected network resulting from activation of axons, including antidromic activation. Here we review current data regarding the local and network activity changes induced by high-frequency stimulation of the subthalamic nucleus and discuss this in the context of motor restoration in Parkinson's disease. Stressing the important functional consequences of axonal activation in deep brain stimulation mechanisms, we highlight the importance of developing anatomical knowledge concerning the fibre connections of the putative therapeutic targets. © 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Maximum on the Electrical Conductivity Polytherm of Molten TeCl4

NASA Astrophysics Data System (ADS)

Salyulev, Alexander B.; Potapov, Alexei M.

2017-05-01

The electrical conductivity of molten TeCl4 was measured up to 761K, i.e. 106 degrees above the normal boiling point of the salt. For the first time it was found that TeCl4 electrical conductivity polytherm has a maximum. It was recorded at 705K (κmax=0.245 Sm/cm), whereupon the conductivity decreases as the temperature rises. The activation energy of electrical conductivity was calculated.

Experimental and numerical investigation of the effective electrical conductivity of nitrogen-doped graphene nanofluids

NASA Astrophysics Data System (ADS)

Mehrali, Mohammad; Sadeghinezhad, Emad; Rashidi, Mohammad Mehdi; Akhiani, Amir Reza; Tahan Latibari, Sara; Mehrali, Mehdi; Metselaar, Hendrik Simon Cornelis

2015-06-01

Electrical conductivity is an important property for technological applications of nanofluids that have not been widely investigated, and few studies have been concerned about the electrical conductivity. In this study, nitrogen-doped graphene (NDG) nanofluids were prepared using the two-step method in an aqueous solution of 0.025 wt% Triton X-100 as a surfactant at several concentrations (0.01, 0.02, 0.04, 0.06 wt%). The electrical conductivity of the aqueous NDG nanofluids showed a linear dependence on the concentration and increased up to 1814.96 % for a loading of 0.06 wt% NDG nanosheet. From the experimental data, empirical models were developed to express the electrical conductivity as functions of temperature and concentration. It was observed that increasing the temperature has much greater effect on electrical conductivity enhancement than increasing the NDG nanosheet loading. Additionally, by considering the electrophoresis of the NDG nanosheets, a straightforward electrical conductivity model is established to modulate and understand the experimental results.

Ultrahigh Oxidation Resistance and High Electrical Conductivity in Copper-Silver Powder

PubMed Central

Li, Jiaxiang; Li, Yunping; Wang, Zhongchang; Bian, Huakang; Hou, Yuhang; Wang, Fenglin; Xu, Guofu; Liu, Bin; Liu, Yong

2016-01-01

The electrical conductivity of pure Cu powder is typically deteriorated at elevated temperatures due to the oxidation by forming non-conducting oxides on surface, while enhancing oxidation resistance via alloying is often accompanied by a drastic decline of electrical conductivity. Obtaining Cu powder with both a high electrical conductivity and a high oxidation resistance represents one of the key challenges in developing next-generation electrical transferring powder. Here, we fabricate a Cu-Ag powder with a continuous Ag network along grain boundaries of Cu particles and demonstrate that this new structure can inhibit the preferential oxidation in grain boundaries at elevated temperatures. As a result, the Cu-Ag powder displays considerably high electrical conductivity and high oxidation resistance up to approximately 300 °C, which are markedly higher than that of pure Cu powder. This study paves a new pathway for developing novel Cu powders with much enhanced electrical conductivity and oxidation resistance in service. PMID:28004839

System and method for evaluating a wire conductor

DOEpatents

Panozzo, Edward; Parish, Harold

2013-10-22

A method of evaluating an electrically conductive wire segment having an insulated intermediate portion and non-insulated ends includes passing the insulated portion of the wire segment through an electrically conductive brush. According to the method, an electrical potential is established on the brush by a power source. The method also includes determining a value of electrical current that is conducted through the wire segment by the brush when the potential is established on the brush. The method additionally includes comparing the value of electrical current conducted through the wire segment with a predetermined current value to thereby evaluate the wire segment. A system for evaluating an electrically conductive wire segment is also disclosed.

Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions

PubMed Central

Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

2011-01-01

Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions. PMID:21505445

Reversible temperature regulation of electrical and thermal conductivity using liquid-solid phase transitions.

PubMed

Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

2011-01-01

Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions.

Depositing bulk or micro-scale electrodes

DOEpatents

Shah, Kedar G.; Pannu, Satinderpall S.; Tolosa, Vanessa; Tooker, Angela C.; Sheth, Heeral J.; Felix, Sarah H.; Delima, Terri L.

2016-11-01

Thicker electrodes are provided on microelectronic device using thermo-compression bonding. A thin-film electrical conducting layer forms electrical conduits and bulk depositing provides an electrode layer on the thin-film electrical conducting layer. An insulating polymer layer encapsulates the electrically thin-film electrical conducting layer and the electrode layer. Some of the insulating layer is removed to expose the electrode layer.

Analogy for Drude's Free Electron Model to Promote Students' Understanding of Electric Circuits in Lower Secondary School

ERIC Educational Resources Information Center

de Almeida, Maria José B. M.; Salvador, Andreia; Costa, Maria Margarida R. R.

2014-01-01

Aiming at a deep understanding of some basic concepts of electric circuits in lower secondary schools, this work introduces an analogy between the behavior of children playing in a school yard with a central lake, subject to different conditions, rules, and stimuli, and Drude's free electron model of metals. Using this analogy from the first…

Help With Depression

MedlinePlus

... techniques that focus on neuromodulation, which incorporates electrical, magnetic or other forms of energy to stimulate brain ... electroconvulsive therapy (ECT), vagus-nerve stimulation (VNS), transcranial magnetic stimulation (TMS) and the experimental deep-brain stimulation ( ...

Variable Anisotropic Brain Electrical Conductivities in Epileptogenic Foci

PubMed Central

Mandelkern, M.; Bui, D.; Salamon, N.; Vinters, H. V.; Mathern, G. W.

2010-01-01

Source localization models assume brain electrical conductivities are isotropic at about 0.33 S/m. These assumptions have not been confirmed ex vivo in humans. This study determined bidirectional electrical conductivities from pediatric epilepsy surgery patients. Electrical conductivities perpendicular and parallel to the pial surface of neocortex and subcortical white matter (n = 15) were measured using the 4-electrode technique and compared with clinical variables. Mean (±SD) electrical conductivities were 0.10 ± 0.01 S/m, and varied by 243% from patient to patient. Perpendicular and parallel conductivities differed by 45%, and the larger values were perpendicular to the pial surface in 47% and parallel in 40% of patients. A perpendicular principal axis was associated with normal, while isotropy and parallel principal axes were linked with epileptogenic lesions by MRI. Electrical conductivities were decreased in patients with cortical dysplasia compared with non-dysplasia etiologies. The electrical conductivity values of freshly excised human brain tissues were approximately 30% of assumed values, varied by over 200% from patient to patient, and had erratic anisotropic and isotropic shapes if the MRI showed a lesion. Understanding brain electrical conductivity and ways to non-invasively measure them are probably necessary to enhance the ability to localize EEG sources from epilepsy surgery patients. PMID:20440549

Deep Eutectic Salt Formulations Suitable as Advanced Heat Transfer Fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raade, Justin; Roark, Thomas; Vaughn, John

2013-07-22

Concentrating solar power (CSP) facilities are comprised of many miles of fluid-filled pipes arranged in large grids with reflective mirrors used to capture radiation from the sun. Solar radiation heats the fluid which is used to produce steam necessary to power large electricity generation turbines. Currently, organic, oil-based fluid in the pipes has a maximum temperature threshold of 400 °C, allowing for the production of electricity at approximately 15 cents per kilowatt hour. The DOE hopes to foster the development of an advanced heat transfer fluid that can operate within higher temperature ranges. The new heat transfer fluid, when usedmore » with other advanced technologies, could significantly decrease solar electricity cost. Lower costs would make solar thermal electricity competitive with gas and coal and would offer a clean, renewable source of energy. Molten salts exhibit many desirable heat transfer qualities within the range of the project objectives. Halotechnics developed advanced heat transfer fluids (HTFs) for application in solar thermal power generation. This project focused on complex mixtures of inorganic salts that exhibited a high thermal stability, a low melting point, and other favorable characteristics. A high-throughput combinatorial research and development program was conducted in order to achieve the project objective. Over 19,000 candidate formulations were screened. The workflow developed to screen various chemical systems to discover salt formulations led to mixtures suitable for use as HTFs in both parabolic trough and heliostat CSP plants. Furthermore, salt mixtures which will not interfere with fertilizer based nitrates were discovered. In addition for use in CSP, the discovered salt mixtures can be applied to electricity storage, heat treatment of alloys and other industrial processes.« less

Assessment of the geothermal resources of the Socialist Republic of Vietnam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flynn, T.; Tien, Phan Cu; Schochert, D.

1997-12-31

More than 125 thermal springs, with temperatures greater than 30{degrees}C have been identified and catalogued by the General Department of Geology of Vietnam. Subsurface data are limited and fewer than 10 areas have been identified, on the basis of chemical geothermometers, as capable of supporting electric power production. Six sites in south-central Vietnam have recently been selected for exploration to determine their development potential for electrical power generation. Selected criteria included surface features, chemical geothermometers, proximity to regional faults trends, and regional requirements for electric power. Site visits were conducted to a total of eight areas in south central Vietnammore » where collateral economic developments suggest the need for a local, reliable source of electricity. Physical and visual information on geothermal springs and wells in Vietnam was compared to Nevada`s geothermal resources. Surface geothermal manifestations in Vietnam appear remarkably similar to those in Nevada. Outcrops adjacent to the geothermal areas indicate that Mesozoic-age granites are the most likely basement rocks. Quaternary basalts mapped throughout the study area may be responsible for the thermal anomaly. Initial exploration efforts will focus on three of the six sites, which together may be able to produce 40 to 60 MWe. A cooperative research program with selected Vietnamese governmental agencies includes geologic mapping, surface geophysical and geochemical surveys, and a graduated schedule of drilling programs, ranging in depth from 100 to 1,000 m. Results will be used to define a detailed, deep drilling and testing program at the three prime sites. Development of geothermal power in this region will boost local economic recovery and add stability to the national electric grid.« less

Decoupling the deep: crop rotations, fertilization and soil physico-chemical properties down the profile

NASA Astrophysics Data System (ADS)

Hobley, Eleanor; Honermeier, Bernd; Don, Axel; Amelung, Wulf; Kögel-Knabner, Ingrid

2017-04-01

Crop fertilization provides vital plant nutrients (e.g. NPK) to ensure yield security but is also associated with negative environmental impacts. In particular, inorganic, mineral nitrogen (Nmin) fertilization leads to emissions during its energy intensive production as well as Nmin leaching to receiving waters. Incorporating legumes into crop rotations can provide organic N to the soil and subsequent crops, reducing the need for mineral N fertilizer and its negative environmental impacts. An added bonus is the potential to enhance soil organic carbon stocks, thereby reducing atmospheric CO2 concentrations. In this study we assessed the effects of legumes in rotation and fertilization regimes on the depth distribution - down to 1 m - of total soil nitrogen (Ntot), soil organic carbon (SOC) as well as isotopic composition (δ13C, δ15N), electrical conductivity and bulk density as well as agricultural yields at a long-term field experiment in Gießen, Germany. Fertilization had significant but small impacts on the soil chemical environment, most particularly the salt content of the soil, with PK fertilization increasing electrical conductivity throughout the soil profile. Similarly, fertilization resulted in a small reduction of soil pH throughout the soil profile. N fertilization, in particular, significantly increased yields, whereas PK fertilizer had only marginal yield effects, indicating that these systems are N limited. This N limitation was confirmed by significant yield benefits with leguminous crops in rotation, even in combination with mineral N fertilizer. The soil was physically and chemically influenced by the choice of crop rotation. Adding clover as a green mulch crop once every 4 years resulted in an enrichment of total N and SOC at the surface compared with fava beans and maize, but only in combination with PK fertilization. In contrast, fava beans and to a lesser extent maize in rotation lowered bulk densities in the subsoil compared with clover. This resulted in a reduction of N density at depth, which was not mirrored in C densities, indicating that fava beans decouple C and N cycles in the deep soil profile. We then tested whether these effects are a result of plant (i.e. enhanced rooting depth associated with lowered subsoil bulk density) or microbial (i.e. N-cycling and denitrification processes) activities, by investigating the isotopic signatures of C and N down the profile. Our results indicate that the selection of crop rotation influences soil C and N cycling and depth distribution. Although mineral N fertilizer has significant benefits for yield, the choice of crop rotation has a greater influence on soil C and N cycling and specifically the addition of leguminous plants into rotation can provide additional yield benefits and stability. Incorporating legumes into crop rotations affects soil physical and chemical properties and decouples C and N cycles in the deep soil profile, indicating different nutrient and water cycling processes in the deep soil profile.

ML-o-Scope: A Diagnostic Visualization System for Deep Machine Learning Pipelines

DTIC Science & Technology

2014-05-16

ML-o-scope: a diagnostic visualization system for deep machine learning pipelines Daniel Bruckner Electrical Engineering and Computer Sciences... machine learning pipelines 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f...the system as a support for tuning large scale object-classification pipelines. 1 Introduction A new generation of pipelined machine learning models

Coated carbon nanotube array electrodes

DOEpatents

Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

2006-12-12

The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

Coated carbon nanotube array electrodes

DOEpatents

Ren, Zhifeng [Newton, MA; Wen, Jian [Newton, MA; Chen, Jinghua [Chestnut Hill, MA; Huang, Zhongping [Belmont, MA; Wang, Dezhi [Wellesley, MA

2008-10-28

The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

Irrigation salinity hazard assessment and risk mapping in the lower Macintyre Valley, Australia.

PubMed

Huang, Jingyi; Prochazka, Melissa J; Triantafilis, John

2016-05-01

In the Murray-Darling Basin of Australia, secondary soil salinization occurs due to excessive deep drainage and the presence of shallow saline water tables. In order to understand the cause and best management, soil and vadose zone information is necessary. This type of information has been generated in the Toobeah district but owing to the state border an inconsistent methodology was used. This has led to much confusion from stakeholders who are unable to understand the ambiguity of the results in terms of final overall risk of salinization. In this research, a digital soil mapping method that employs various ancillary data is presented. Firstly, an electromagnetic induction survey using a Geonics EM34 and EM38 was used to characterise soil and vadose zone stratigraphy. From the apparent electrical conductivity (ECa) collected, soil sampling locations were selected and with laboratory analysis carried out to determine average (2-12m) clay and EC of a saturated soil-paste extract (ECe). EM34 ECa, land surface parameters derived from a digital elevation model and measured soil data were used to establish multiple linear regression models, which allowed for mapping of various hazard factors, including clay and ECe. EM38 ECa data were calibrated to deep drainage obtained from Salt and Leaching Fraction (SaLF) modelling of soil data. Expert knowledge and indicator kriging were used to determine critical values where the salinity hazard factors were likely to contribute to a shallow saline water table (i.e., clay ≤35%; ECe>2.5dS/m, and deep drainage >100mm/year). This information was combined to produce an overall salinity risk map for the Toobeah district using indicator kriging. The risk map shows potential salinization areas and where detailed information is required and where targeted research can be conducted to monitor soil conditions and water table heights and determine best management strategies. Copyright © 2016 Elsevier B.V. All rights reserved.

Ceramic substrate including thin film multilayer surface conductor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolf, Joseph Ambrose; Peterson, Kenneth A.

2017-05-09

A ceramic substrate comprises a plurality of ceramic sheets, a plurality of inner conductive layers, a plurality of vias, and an upper conductive layer. The ceramic sheets are stacked one on top of another and include a top ceramic sheet. The inner conductive layers include electrically conductive material that forms electrically conductive features on an upper surface of each ceramic sheet excluding the top ceramic sheet. The vias are formed in each of the ceramic sheets with each via being filled with electrically conductive material. The upper conductive layer includes electrically conductive material that forms electrically conductive features on anmore » upper surface of the top ceramic sheet. The upper conductive layer is constructed from a stack of four sublayers. A first sublayer is formed from titanium. A second sublayer is formed from copper. A third sublayer is formed from platinum. A fourth sublayer is formed from gold.« less

Estimates of olivine-basaltic melt electrical conductivity using a digital rock physics approach

NASA Astrophysics Data System (ADS)

Miller, Kevin J.; Montési, Laurent G. J.; Zhu, Wen-lu

2015-12-01

Estimates of melt content beneath fast-spreading mid-ocean ridges inferred from magnetotelluric tomography (MT) vary between 0.01 and 0.10. Much of this variation may stem from a lack of understanding of how the grain-scale melt geometry influences the bulk electrical conductivity of a partially molten rock, especially at low melt fraction. We compute bulk electrical conductivity of olivine-basalt aggregates over 0.02 to 0.20 melt fraction by simulating electric current in experimentally obtained partially molten geometries. Olivine-basalt aggregates were synthesized by hot-pressing San Carlos olivine and high-alumina basalt in a solid-medium piston-cylinder apparatus. Run conditions for experimental charges were 1.5 GPa and 1350 °C. Upon completion, charges were quenched and cored. Samples were imaged using synchrotron X-ray micro-computed tomography (μ-CT). The resulting high-resolution, 3-dimensional (3-D) image of the melt distribution constitutes a digital rock sample, on which numerical simulations were conducted to estimate material properties. To compute bulk electrical conductivity, we simulated a direct current measurement by solving the current continuity equation, assuming electrical conductivities for olivine and melt. An application of Ohm's Law yields the bulk electrical conductivity of the partially molten region. The bulk electrical conductivity values for nominally dry materials follow a power-law relationship σbulk = Cσmeltϕm with fit parameters m = 1.3 ± 0.3 and C = 0.66 ± 0.06. Laminar fluid flow simulations were conducted on the same partially molten geometries to obtain permeability, and the respective pathways for electrical current and fluid flow over the same melt geometry were compared. Our results indicate that the pathways for flow fluid are different from those for electric current. Electrical tortuosity is lower than fluid flow tortuosity. The simulation results are compared to existing experimental data, and the potential influence of volatiles and melt films on electrical conductivity of partially molten rocks is discussed.

Photovoltaic device having light transmitting electrically conductive stacked films

DOEpatents

Weber, Michael F.; Tran, Nang T.; Jeffrey, Frank R.; Gilbert, James R.; Aspen, Frank E.

1990-07-10

A light transmitting electrically conductive stacked film, useful as a light transmitting electrode, including a first light transmitting electrically conductive layer, having a first optical thickness, a second light transmitting layer, having a second optical thickness different from the optical thickness of the first layer, and an electrically conductive metallic layer interposed between and in initimate contact with the first and second layers.

Heat operated cryogenic electrical generator

NASA Technical Reports Server (NTRS)

Wang, T. G.; Saffren, M. M.; Elleman, D. D. (Inventor)

1975-01-01

An electrical generator useful for providing electrical power in deep space, is disclosed. The electrical generator utilizes the unusual hydrodynamic property exhibited by liquid helium as it is converted to and from a superfluid state to cause opposite directions of rotary motion for a rotor cell thereof. The physical motion of the rotor cell was employed to move a magnetic field provided by a charged superconductive coil mounted on the exterior of the cell. An electrical conductor was placed in surrounding proximity to the cell to interact with the moving magnetic field provided by the superconductive coil and thereby generate electrical energy. A heat control arrangement was provided for the purpose of causing the liquid helium to be partially converted to and from a superfluid state by being cooled and heated, respectively.

Electric moisture meters for wood

Treesearch

William L. James

1988-01-01

Electric moisture meters for wood measure electric conductance (resistance) or dielectric properties, which vary fairly consistently with moisture content when it is less than 30 percent. The two major classes of electric moisture meters are the conductance (resistance) type and the dielectric type. Conductance-t ype meters use penetrating electrodes that measure in a...

Atelocollagen sponge and recombinant basic fibroblast growth factor combination therapy for resistant wounds with deep cavities.

PubMed

Nakanishi, Asako; Hakamada, Arata; Isoda, Ken-ichi; Mizutani, Hitoshi

2005-05-01

Recent advances in bioengineering have introduced materials that enhance wound healing. Even with such new tools, some deep ulcers surrounded by avascular tissues, including bone, tendon, and fascia, are resistant to various therapies and easily form deep cavities with loss of subcutaneous tissue. Atelocollagen sponges have been used as an artificial dermis to cover full-thickness skin defects. Topical recombinant human basic fibroblast growth factor has been introduced as a growth factor to induce fibroblast proliferation in skin ulcers. We applied these materials in combination in two patients with deep resistant wounds: one with a cavity reaching the mediastinum through a divided sternum and one with deep necrotic wounds caused by electric burns. These wounds did not respond to the topical basic fibroblast growth factor alone. In contrast, the combination therapy closed the wounds rapidly without further surgical treatment. This combination therapy is a potent treatment for resistant wounds with deep cavities.

Electrically-Conductive Polyaramid Cable And Fabric

NASA Technical Reports Server (NTRS)

Orban, Ralph F.

1988-01-01

Tows coated with metal provide strength and conductance. Cable suitable for use underwater made of electrically conductive tows of metal-coated polyaramid filaments surrounded by electrically insulating jacket. Conductive tows used to make conductive fabrics. Tension borne by metal-coated filaments, so upon release, entire cable springs back to nearly original length without damage.

Improved 2-D resistivity imaging of features in covered karst terrain with arrays of implanted electrodes

NASA Astrophysics Data System (ADS)

Kiflu, H. G.; Kruse, S. E.; Harro, D.; Loke, M. H.; Wilkinson, P. B.

2013-12-01

Electrical resistivity tomography is commonly used to identify geologic features associated with sinkhole formation. In covered karst terrain, however, it can be difficult to resolve the depth to top of limestone with this method. This is due to the fact that array lengths, and hence depth of resolution, are often limited by residential or commercial lot dimensions in urban environments. Furthermore, the sediments mantling the limestone are often clay-rich and highly conductive. The resistivity method has limited sensitivity to resistive zones beneath conductive zones. This sensitivity can be improved significantly with electrodes implanted at depth in the cover sediments near the top of limestone. An array of deep electrodes is installed with direct push technology in the karst cover. When combined with a surface array in which each surface electrode is underlain by a deep electrode, the array geometry is similar to a borehole array turned on its side. This method, called the Multi-Electrode Resistivity Implant Technique (MERIT), offers the promise of significantly improved resolution of epikarst and cover collapse development zones in the overlying sediment, the limestone or at the sediment-bedrock interface in heterogeneous karst environments. With a non-traditional array design, the question of optimal array geometries arises. Optimizing array geometries is complicated by the fact that many plausible 4-electrode readings will produce negative apparent resistivity values, even in homogeneous terrain. Negative apparent resistivities cannot be used in inversions based on the logarithm of the apparent resistivity. New algorithms for seeking optimal array geometries have been developed by modifying the 'Compare R' method of Wilkinson and Loke. The optimized arrays show significantly improved resolution over basic arrays adapted from traditional 2D surface geometries. Several MERIT case study surveys have been conducted in covered karst in west-central Florida, with 28-electrode arrays with electrodes 2-5 meters apart, and the deep arrays buried at 4-8 meters depth. Ground penetrating radar surveys, SPT borings and coring data provide selected 'ground truthing'. The case studies show that inclusion of the deep electrode array permits karst features such as undulations at the top of limestone and raveling zones within surficial sediments to be imaged. These features are not accessible from surface arrays with equivalent surface footprints. The method also has better resolution at depth at the ends of the lines, where surface arrays are typically plotted with a trapezoidal truncation due to poor resolution at the lower corners of the profile.

Simulation and Performance Analysis of Lithium Battery Bank Mounted on the Hybrid Power System for Mobile Public Health Center

NASA Astrophysics Data System (ADS)

Busono, Pratondo; Kartini, Evvy

2013-07-01

Mobile medical clinic has been proposed to serve homeless people, people in the disaster area or in the remote area where no health service exist. At that site, a number of essential services such as primary health care, general health screening, medical treatment and emergency/rescue operations are required. Such services usually requires on board electrical equipments such as refrigerators, komputer, power tools and medical equipments. To supply such electrical equipments, it needs extra auxiliary power sources, in addition of standard automotive power supply. The auxiliary power source specifically design to supply non automotive load which may have similar configuration, but usually uses high power alternator rated and larger deep cycle on board battery bank. This study covers the modeling and dynamic simulation of auxiliary power source/battery to supply the medical equipment and other electrical equipments on board. It consists a variable speed diesel generator set, photovoltaic (PV) generator mounted on the roof of the car, a rechargable battery bank. As an initial step in the system design, a simulation study was performed. The simulation is conducted in the system level. Simulation results shows that dynamical behaviour by means of current density, voltage and power plot over a chosen time range, and functional behaviour such as charging and discharging characteristic of the battery bank can be obtained.

Hole-to-surface resistivity measurements at Gibson Dome (drill hole GD-1) Paradox basin, Utah

USGS Publications Warehouse

Daniels, J.J.

1984-01-01

Hole-to-surface resistivity measurements were made in a deep drill hole (GD-1), in San Juan County, Utah, which penetrated a sequence of sandstone, shale, and evaporite. These measurements were made as part of a larger investigation to study the suitability of an area centered around the Gibson Dome structure for nuclear waste disposal. The magnitude and direction of the total electric field resulting from a current source placed in a drill hole is calculated from potential difference measurements for a grid of closely-spaced stations. A contour map of these data provides a detailed map of the distribution of the electric field away from the drill hole. Computation of the apparent resistivity from the total electric field helps to interpret the data with respect to the ideal situation of a layered earth. Repeating the surface measurements for different source depths gives an indication of variations in the geoelectric section with depth. The quantitative interpretation of the field data at Gibson Dome was hindered by the pressure of a conductive borehole fluid. However, a qualitative interpretation of the field data indicates the geoelectric section around drill hole GD-1 is not perfectly layered. The geoelectric section appears to dip to the northwest, and contains anomalies in the resistivity distribution that may be representative of localized thickening or folding of the salt layers.

Effect of process parameters on microstructure and electrical conductivity during FSW of Al-6101 and Pure Copper

NASA Astrophysics Data System (ADS)

Sharma, Nidhi; Khan, Zahid A.; Siddiquee, Arshad Noor; Shihab, Suha K.; Atif Wahid, Mohd

2018-04-01

Copper (Cu) is predominantly used material as a conducting element in electrical and electronic components due to its high conductivity. Aluminum (Al) being lighter in weight and more conductive on weight basis than that of Cu is able to replace or partially replace Cu to make lighter and cost effective electrical components. Conventional methods of joining Al to Cu, such as, fusion welding process have many shortcomings. Friction Stir Welding (FSW) is a solid state welding process which overcomes the shortcoming of the fusion welding. FSW parameters affect the mechanical and electrical properties of the joint. This study aims to evaluate the effect of different process parameters such as shoulder diameter, pin offset, welding and rotational speed on the microstructure and electrical conductivity of the dissimilar Al-Cu joint. FSW is performed using cylindrical pin profile, and four process parameters. Each parameter at different levels is varied according to Taguchi’s L18 standard orthogonal array. It is found that the electrical conductivity of the FSWed joints are equal to that of aluminum at all the welded sections. FSW is found to be an effective technique to join Al to Cu without compromising with the electrical properties. However, the electrical conductivity gets influenced by the process parameters in the stir zone. The optimal combination of the FSW parameters for maximum electrical conductivity is determined. The analysis of variance (ANOVA) technique applied on stir zone suggests that the rotational speed and tool pin offset are the significant parameters to influence the electrical conductivity.

Properties of transparent conducting tin monoxide(SnO) thin films prepared by chemical spray pyrolysis method

NASA Astrophysics Data System (ADS)

Eqbal, Ebitha; Anila, E. I.

2018-01-01

Transparent conducting Stannous Oxide (SnO) thin films were obtained by chemical spray pyrolysis method on glass substrates for 0.1 M and 0.25 M concentration of precursor solutions. Their structural, morphological, optical and electrical properties were investigated. X-ray diffraction (XRD) study shows polycrystalline nature of the films with orthorhombic crystal structure. The morphological analysis was carried out by Scanning electron microscopy (SEM) and elemental analysis was done by Energy dispersive X-ray spectroscopy (EDX). The band gap of 0.1 M and 0.25 M thin film samples were found to be 3.58eV with 82% transmission and 3 eV with 30% transmission respectively. The film thickness, refractive index (n) and extinction coefficient (k) of the films were obtained by ellipsometric technique. Hall effect measurements reveal p-type conduction with mobility 7.8 cm2V-1s-1 and 15 cm2V-1s-1 and conductivity of 8.5 S/cm and 17.1 S/cm respectively for the 0.1 M and 0.25 M samples. Photoluminescence (PL) spectrum of the samples show a broad emission which covers near band edge (NBE) as well as deep level emission (DLE) in the region 380 nm-620 nm.

Minimizing radiation damage in nonlinear optical crystals

DOEpatents

Cooke, D.W.; Bennett, B.L.; Cockroft, N.J.

1998-09-08

Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal. 5 figs.

A magnetotelluric feasibility study of the Alps

NASA Astrophysics Data System (ADS)

Ritter, O.; Weckmann, U.

2016-12-01

The Alps are a famous and extensive mountain range system in central Europe. The mountains were formed as the African and Eurasian tectonic plates collided and they have been a prime target for geological and geophysical investigations since the beginning of modern geosciences. Consequently, the Alps have been investigated with active and passive seismological methods and extensive sets of potential field data exist. Hardly anything is known, however, about the deep electrical conductivity structure, as it has been notoriously difficult to acquire magnetotelluric (MT) data in the Alps. The Alps are densely populated and a lot of infrastructure for tourism has been built over the years. MT measurements, which rely on natural variations of the electromagnetic background fields, are severely hampered by this man-made noise. Here, we report on a feasibility study to acquire MT data in the Alps, where all stations are deployed outside the valleys, on high mountain ranges and alpine pastures. Overall we recorded MT data at 7 stations, along an approximately north-south profile centred on Mayrhofen in the Austrian Alps. The average station spacing was 5 kilometers. The data were processed using robust remote-reference processing and the results clearly show that MT measurements are feasible. We used Mare2DEM for 2D inversion to include a somewhat realistic topography. The 2D section indicates moderate resistivity for the top 2 - 5 km, consistent with the regional geology, which suggests (meta-) sedimentary sequences. From depths of 5 km and below resistivities exceed 5,000 Ohmm. This means we can sense very deep with MT but also, that we should be cautious with an interpretation of this short profile. The data also clearly indicate 3D effects. We therefore propose to deploy an array of stations covering the entire Alps in USArray style, e.g. with a station spacing of approximately 50 km, to derive a 3D model of the deep electrical resistivity structure of the Alps. Such a model could also serve as reference for more detailed investigations of key structures such as major fault systems or nappe structures. It will be essential to install stations on high ground, as far away as possible from valleys and cultural installations.

Nature of Dielectric Properties, Electric Modulus and AC Electrical Conductivity of Nanocrystalline ZnIn2Se4 Thin Films

NASA Astrophysics Data System (ADS)

El-Nahass, M. M.; Attia, A. A.; Ali, H. A. M.; Salem, G. F.; Ismail, M. I.

2018-02-01

The structural characteristics of thermally deposited ZnIn2Se4 thin films were indexed utilizing x-ray diffraction as well as scanning electron microscopy techniques. Dielectric properties, electric modulus and AC electrical conductivity of ZnIn2Se4 thin films were examined in the frequency range from 42 Hz to 106 Hz. The capacitance, conductance and impedance were measured at different temperatures. The dielectric constant and dielectric loss decrease with an increase in frequency. The maximum barrier height was determined from the analysis of the dielectric loss depending on the Giuntini model. The real part of the electric modulus revealed a constant maximum value at higher frequencies and the imaginary part of the electric modulus was characterized by the appearance of dielectric relaxation peaks. The AC electrical conductivity obeyed the Jonscher universal power law. Correlated barrier hopping model was the appropriate mechanism for AC conduction in ZnIn2Se4 thin films. Estimation of the density of states at the Fermi level and activation energy, for AC conduction, was carried out based on the temperature dependence of AC electrical conductivity.

Grain boundary dominated electrical conductivity in ultrananocrystalline diamond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiora, Neda; Mertens, Michael; Bruhne, Kai

Here, N-type electrically conductive ultrananocrystalline diamond (UNCD) films were deposited using the hot filament chemical vapor deposition technique with a gas mixture of H 2, CH 4 and NH 3. Depending on the deposition temperature and ammonia feed gas concentration, which serves as a nitrogen source, room temperature electrical conductivities in the order of 10 –2 to 5 × 10 1S/cm and activation energies in the meV range were achieved. In order to understand the origin of the enhanced electrical conductivity and clarify the role of ammonia addition to the process gas, a set of UNCD films was grown bymore » systematically varying the ammonia gas phase concentration. These samples were analyzed with respect to their morphology and electrical properties as well as their carbon and nitrogen bonding environments. Temperature dependent electrical conductivity measurements (300–1200 K) show that the electrical conductivity of the samples increases with temperature. The near edge x-ray absorption fine structure measurements reveal that the electrical conductivity of the UNCD films does not correlate directly with ammonia addition, but depends on the total amount of sp2 bonded carbon in the deposited films.« less

Grain boundary dominated electrical conductivity in ultrananocrystalline diamond

DOE PAGES

Wiora, Neda; Mertens, Michael; Bruhne, Kai; ...

2017-10-09

Here, N-type electrically conductive ultrananocrystalline diamond (UNCD) films were deposited using the hot filament chemical vapor deposition technique with a gas mixture of H 2, CH 4 and NH 3. Depending on the deposition temperature and ammonia feed gas concentration, which serves as a nitrogen source, room temperature electrical conductivities in the order of 10 –2 to 5 × 10 1S/cm and activation energies in the meV range were achieved. In order to understand the origin of the enhanced electrical conductivity and clarify the role of ammonia addition to the process gas, a set of UNCD films was grown bymore » systematically varying the ammonia gas phase concentration. These samples were analyzed with respect to their morphology and electrical properties as well as their carbon and nitrogen bonding environments. Temperature dependent electrical conductivity measurements (300–1200 K) show that the electrical conductivity of the samples increases with temperature. The near edge x-ray absorption fine structure measurements reveal that the electrical conductivity of the UNCD films does not correlate directly with ammonia addition, but depends on the total amount of sp2 bonded carbon in the deposited films.« less

Gasket Assembly for Sealing Mating Surfaces

NASA Technical Reports Server (NTRS)

Bryant, Melvin A., III (Inventor)

2003-01-01

A pair of substantially opposed mating surfaces are joined to each other and sealed in place by means of an electrically-conductive member which is placed in proximity to the mating surfaces. The electrically-conductive member has at least one element secured thereto which is positioned to contact the mating surfaces, and which softens when the electrically-conductive member is heated by passing an electric current therethrough. The softened element conforms to the mating surfaces, and upon cooling of the softened element the mating surfaces are joined together in an effective seal. Of particular significance is an embodiment of the electrically-conductive member which is a gasket having an electrically-conductive gasket base and a pair of the elements secured to opposite sides of the gasket base. This embodiment is positioned between the opposed mating surfaces to be joined to each other. Also significant is an embodiment of the electrically-conductive member which is an electrically-conductive sleeve having an element secured to its inner surface. This embodiment surrounds cylindrical members the bases of which are the substantially opposed mating surfaces to be joined, and the element on the inner surface of the sleeve contacts the outer surfaces of the cylindrical members.

150 kW Class Solar Electric Propulsion Spacecraft Power Architecture Model

NASA Technical Reports Server (NTRS)

Csank, Jeffrey T.; Aulisio, Michael V.; Loop, Benjamin

2017-01-01

The National Aeronautics and Space Administration (NASA) Solar Electric Propulsion Technology Demonstration Mission in conjunction with PC Krause and Associates has created a Simulink-based power architecture model for a 50 kilo-Watt (kW) solar electric propulsion system. NASA has extended this model to investigate 150 kW solar electric propulsion systems. Increasing the power system capability from 50 kW to 150 kW better aligns with the anticipated power requirements for Mars and other deep space explorations. The high-power solar electric propulsion capability has been identified as a critical part of NASAs future beyond-low-Earth-orbit for human-crewed exploration missions. This paper presents multiple 150 kW architectures, simulation results, and a discussion of their merits.

Comparison of Solar Electric and Chemical Propulsion Missions

NASA Technical Reports Server (NTRS)

Freeh, Joshua E.; Burke, Laura M.; Sjauw, Waldy K.; McGuire, Melissa L.; Smith, Bryan K.

2015-01-01

Solar Electric Propulsion (SEP) offers fuel efficiency and mission robustness for spacecraft. The combination of solar power and electric propulsion engines is currently used for missions ranging from geostationary stationkeeping to deep space science because of these benefits. Both solar power and electric propulsion technologies have progressed to the point where higher electric power systems can be considered, making substantial cargo missions and potentially human missions viable. This paper evaluates and compares representative lunar, Mars, and Sun-Earth Langrangian point missions using SEP and chemical propulsion subsystems. The potential benefits and limitations are discussed along with technology gaps that need to be resolved for such missions to become possible. The connection to NASA's human architecture and technology development efforts will be discussed.

Anisotropic electrical and thermal conductivity in Bi2AE2Co2O8+δ [AE = Ca, Sr1-xBax (x = 0.0, 0.25, 0.5, 0.75, 1.0)] single crystals

NASA Astrophysics Data System (ADS)

Dong, Song-Tao; Zhang, Bin-Bin; Xiong, Ye; Lv, Yang-Yang; Yao, Shu-Hua; Chen, Y. B.; Zhou, Jian; Zhang, Shan-Tao; Chen, Yan-Feng

2015-09-01

Bi2AE2Co2O8+δ (AE represents alkaline earth), constructed by stacking of rock-salt Bi2AE2O4 and triangle CoO2 layers alternatively along c-axis, is one of promising thermoelectric oxides. The most impressive feature of Bi2AE2Co2O8+δ, as reported previously, is their electrical conductivity mainly lying along CoO2 plane, adjusting Bi2AE2O4 layer simultaneously manipulates both thermal conductivity and electrical conductivity. It in turn optimizes thermoelectric performance of these materials. In this work, we characterize the anisotropic thermal and electrical conductivity along both ab-plane and c-direction of Bi2AE2Co2O8+δ (AE = Ca, Sr, Ba, Sr1-xBax) single crystals. The results substantiate that isovalence replacement in Bi2AE2Co2O8+δ remarkably modifies their electrical property along ab-plane; while their thermal conductivity along ab-plane only has a slightly difference. At the same time, both the electrical conductivity and thermal conductivity along c-axis of these materials also have dramatic changes. Certainly, the electrical resistance along c-axis is too high to be used as thermoelectric applications. These results suggest that adjusting nano-block Bi2AE2O4 layer in Bi2AE2Co2O8+δ cannot modify the thermal conductivity along high electrical conductivity plane (ab-plane here). The evolution of electrical property is discussed by Anderson localization and electron-electron interaction U. And the modification of thermal conductivity along c-axis is attributed to the microstructure difference. This work sheds more light on the manipulation of the thermal and electrical conductivity in the layered thermoelectric materials.

Electrically conductive material

DOEpatents

Singh, Jitendra P.; Bosak, Andrea L.; McPheeters, Charles C.; Dees, Dennis W.

1993-01-01

An electrically conductive material for use in solid oxide fuel cells, electrochemical sensors for combustion exhaust, and various other applications possesses increased fracture toughness over available materials, while affording the same electrical conductivity. One embodiment of the sintered electrically conductive material consists essentially of cubic ZrO.sub.2 as a matrix and 6-19 wt. % monoclinic ZrO.sub.2 formed from particles having an average size equal to or greater than about 0.23 microns. Another embodiment of the electrically conductive material consists essentially at cubic ZrO.sub.2 as a matrix and 10-30 wt. % partially stabilized zirconia (PSZ) formed from particles having an average size of approximately 3 microns.

Crop response to deep tillage - a meta-analysis

NASA Astrophysics Data System (ADS)

Schneider, Florian; Don, Axel; Hennings, Inga; Schmittmann, Oliver; Seidel, Sabine J.

2017-04-01

Subsoil, i.e. the soil layer below the topsoil, stores tremendous stocks of nutrients and can keep water even under drought conditions. Deep tillage may be a method to enhance the plant-availability of subsoil resources. However, in field trials, deep tillage effects on crop yields were inconsistent. Therefore, we conducted a meta-analysis of crop yield response to subsoiling, deep ploughing and deep mixing of soil profiles. Our search resulted in 1530 yield comparisons following deep and conventional control tillage on 67 experimental cropping sites. The vast majority of the data derived from temperate latitudes, from trials conducted in the USA (679 observations) and Germany (630 observations). On average, crop yield response to deep tillage was slightly positive (6% increase). However, individual deep tillage effects were highly scattered including about 40% yield depressions after deep tillage. Deep tillage on soils with root restrictive layers increased crop yields about 20%, while soils containing >70% silt increased the risk of yield depressions following deep tillage. Generally, deep tillage effects increased with drought intensity indicating deep tillage as climate adaptation measure at certain sites. Our results suggest that deep tillage can facilitate the plant-availability of subsoil nutrients, which increases crop yields if (i) nutrients in the topsoil are growth limiting, and (ii) deep tillage does not come at the cost of impairing topsoil fertility. On sites with root restrictive soil layers, deep tillage can be an effective measure to mitigate drought stress and improve the resilience of crops. However, deep tillage should only be performed on soils with a stable structure, i.e. <70% silt content. We will discuss the contribution of deep tillage options to enhance the sustainability of agricultural production by facilitating the uptake of nutrients and water from the subsoil.

Contact-independent electrical conductance measurement

DOEpatents

Mentzel, Tamar S.; MacLean, Kenneth; Kastner, Marc A.; Ray, Nirat

2017-01-24

Electrical conductance measurement system including a one-dimensional semiconducting channel, with electrical conductance sensitive to electrostatic fluctuations, in a circuit for measuring channel electrical current. An electrically-conductive element is disposed at a location at which the element is capacitively coupled to the channel; a midpoint of the element aligned with about a midpoint of the channel, and connected to first and second electrically-conductive contact pads that are together in a circuit connected to apply a changing voltage across the element. The electrically-conductive contact pads are laterally spaced from the midpoint of the element by a distance of at least about three times a screening length of the element, given in SI units as (K.di-elect cons..sub.0/e.sup.2D(E.sub.F)).sup.1/2, where K is the static dielectric constant, .di-elect cons..sub.0 is the permittivity of free space, e is electron charge, and D(E.sub.F) is the density of states at the Fermi energy for the element.

The Importance of Conducting Life Sciences Experiments on the Deep Space Gateway Platform

NASA Astrophysics Data System (ADS)

Bhattacharya, S.

2018-02-01

Life science research on the Deep Space Gateway platform is an important precursor for long term human exploration of deep space. Ideas for utilizing flight hardware and well characterized model organisms will be discussed.

A Programmable High-Voltage Compliance Neural Stimulator for Deep Brain Stimulation in Vivo

PubMed Central

Gong, Cihun-Siyong Alex; Lai, Hsin-Yi; Huang, Sy-Han; Lo, Yu-Chun; Lee, Nicole; Chen, Pin-Yuan; Tu, Po-Hsun; Yang, Chia-Yen; Lin, James Chang-Chieh; Chen, You-Yin

2015-01-01

Deep brain stimulation (DBS) is one of the most effective therapies for movement and other disorders. The DBS neurosurgical procedure involves the implantation of a DBS device and a battery-operated neurotransmitter, which delivers electrical impulses to treatment targets through implanted electrodes. The DBS modulates the neuronal activities in the brain nucleus for improving physiological responses as long as an electric discharge above the stimulation threshold can be achieved. In an effort to improve the performance of an implanted DBS device, the device size, implementation cost, and power efficiency are among the most important DBS device design aspects. This study aims to present preliminary research results of an efficient stimulator, with emphasis on conversion efficiency. The prototype stimulator features high-voltage compliance, implemented with only a standard semiconductor process, without the use of extra masks in the foundry through our proposed circuit structure. The results of animal experiments, including evaluation of evoked responses induced by thalamic electrical stimuli with our fabricated chip, were shown to demonstrate the proof of concept of our design. PMID:26029954

Electroluminescence and other diagnostic techniques for the study of hot-electron effects in compound semiconductor devices

NASA Astrophysics Data System (ADS)

Zanoni, Enrico; Meneghesso, Gaudenzio; Menozzi, Roberto

2000-03-01

Hot electron in III-V FETs can be indirectly monitored by measuring the current coming out from the gate when the device is biased at high electric fields. This negative current is due to the collection of holes generated by impact ionization in the gate-to drain region. Electroluminescence represents a powerful tool in order to characterize not only hot electrons but also material properties. By using spatially resolved emission microscopy it is possible to show that the light due to cold electron/hole recombination is emitted between the gate and the source (low electric field region), while the contribution due to hot electrons is emitted between the gate and the drain (high electric field region). Deep-traps created in the device by hot carriers can be analysed by means of drain current deep level transient spectroscopy and by transconductance frequency dispersion. Cathodoluminescence, optical beam induced current, X-ray spectroscopy, electron energy loss spectroscopy in combination with a transmission electron microscopy are powerful tools in order to identify and localize surface modification following hot-electron stress tests.

Power Processing for a Conceptual Project Prometheus Electric Propulsion System

NASA Technical Reports Server (NTRS)

Scina, Joseph E., Jr.; Aulisio, Michael; Gerber, Scott S.; Hewitt, Frank; Miller, Leonard; Elbuluk, Malik; Pinero, Luis R. (Technical Monitor)

2005-01-01

NASA has proposed a bold mission to orbit and explore the moons of Jupiter. This mission, known as the Jupiter Icy Moons Orbiter (JIMO), would significantly increase NASA s capability to explore deep space by making use of high power electric propulsion. One electric propulsion option under study for JIMO is an ion propulsion system. An early version of an ion propulsion system was successfully used on NASA's Deep Space 1 mission. One concept for an ion thruster system capable of meeting the current JIMO mission requirement would have individual thrusters that are 16 to 25 kW each and require voltages as high as 8.0 kV. The purpose of this work is to develop power processing schemes for delivering the high voltage power to the spacecraft ion thrusters based upon a three-phase AC distribution system. In addition, a proposed DC-DC converter topology is presented for an ion thruster ancillary supply based upon a DC distribution system. All specifications discussed in this paper are for design convenience and are speculative in nature.

Conceptualization and validation of an open-source closed-loop deep brain stimulation system in rat.

PubMed

Wu, Hemmings; Ghekiere, Hartwin; Beeckmans, Dorien; Tambuyzer, Tim; van Kuyck, Kris; Aerts, Jean-Marie; Nuttin, Bart

2015-04-21

Conventional deep brain stimulation (DBS) applies constant electrical stimulation to specific brain regions to treat neurological disorders. Closed-loop DBS with real-time feedback is gaining attention in recent years, after proved more effective than conventional DBS in terms of pathological symptom control clinically. Here we demonstrate the conceptualization and validation of a closed-loop DBS system using open-source hardware. We used hippocampal theta oscillations as system input, and electrical stimulation in the mesencephalic reticular formation (mRt) as controller output. It is well documented that hippocampal theta oscillations are highly related to locomotion, while electrical stimulation in the mRt induces freezing. We used an Arduino open-source microcontroller between input and output sources. This allowed us to use hippocampal local field potentials (LFPs) to steer electrical stimulation in the mRt. Our results showed that closed-loop DBS significantly suppressed locomotion compared to no stimulation, and required on average only 56% of the stimulation used in open-loop DBS to reach similar effects. The main advantages of open-source hardware include wide selection and availability, high customizability, and affordability. Our open-source closed-loop DBS system is effective, and warrants further research using open-source hardware for closed-loop neuromodulation.

Conceptualization and validation of an open-source closed-loop deep brain stimulation system in rat

PubMed Central

Wu, Hemmings; Ghekiere, Hartwin; Beeckmans, Dorien; Tambuyzer, Tim; van Kuyck, Kris; Aerts, Jean-Marie; Nuttin, Bart

2015-01-01

Conventional deep brain stimulation (DBS) applies constant electrical stimulation to specific brain regions to treat neurological disorders. Closed-loop DBS with real-time feedback is gaining attention in recent years, after proved more effective than conventional DBS in terms of pathological symptom control clinically. Here we demonstrate the conceptualization and validation of a closed-loop DBS system using open-source hardware. We used hippocampal theta oscillations as system input, and electrical stimulation in the mesencephalic reticular formation (mRt) as controller output. It is well documented that hippocampal theta oscillations are highly related to locomotion, while electrical stimulation in the mRt induces freezing. We used an Arduino open-source microcontroller between input and output sources. This allowed us to use hippocampal local field potentials (LFPs) to steer electrical stimulation in the mRt. Our results showed that closed-loop DBS significantly suppressed locomotion compared to no stimulation, and required on average only 56% of the stimulation used in open-loop DBS to reach similar effects. The main advantages of open-source hardware include wide selection and availability, high customizability, and affordability. Our open-source closed-loop DBS system is effective, and warrants further research using open-source hardware for closed-loop neuromodulation. PMID:25897892

Conducting single-molecule magnet materials.

PubMed

Cosquer, Goulven; Shen, Yongbing; Almeida, Manuel; Yamashita, Masahiro

2018-05-11

Multifunctional molecular materials exhibiting electrical conductivity and single-molecule magnet (SMM) behaviour are particularly attractive for electronic devices and related applications owing to the interaction between electronic conduction and magnetization of unimolecular units. The preparation of such materials remains a challenge that has been pursued by a bi-component approach of combination of SMM cationic (or anionic) units with conducting networks made of partially oxidized (or reduced) donor (or acceptor) molecules. The present status of the research concerning the preparation of molecular materials exhibiting SMM behaviour and electrical conductivity is reviewed, describing the few molecular compounds where both SMM properties and electrical conductivity have been observed. The evolution of this research field through the years is discussed. The first reported compounds are semiconductors in spite being able to present relatively high electrical conductivity, and the SMM behaviour is observed at low temperatures where the electrical conductivity of the materials is similar to that of an insulator. During the recent years, a breakthrough has been achieved with the coexistence of high electrical conductivity and SMM behaviour in a molecular compound at the same temperature range, but so far without evidence of a synergy between these properties. The combination of high electrical conductivity with SMM behaviour requires not only SMM units but also the regular and as far as possible uniform packing of partially oxidized molecules, which are able to provide a conducting network.

The electrical conductivity of in vivo human uterine fibroids.

PubMed

DeLonzor, Russ; Spero, Richard K; Williams, Joseph J

2011-01-01

The purpose of this study was to determine the value of electrical conductivity that can be used for numerical modelling in vivo radiofrequency ablation (RFA) treatments of human uterine fibroids. No experimental electrical conductivity data have previously been reported for human uterine fibroids. In this study electrical data (voltage) from selected in vivo clinical procedures on human uterine fibroids were used to numerically model the treatments. Measured versus calculated power dissipation profiles were compared to determine uterine fibroid electrical conductivity. Numerical simulations were conducted utilising a wide range of values for tissue thermal conductivity, heat capacity and blood perfusion coefficient. The simulations demonstrated that power dissipation was insensitive to the exact values of these parameters for the simulated geometry, treatment duration, and power level. Consequently, it was possible to determine tissue electrical conductivity without precise knowledge of the values for these parameters. Results of this study showed that an electrical conductivity for uterine fibroids of 0.305 S/m at 37°C and a temperature coefficient of 0.2%/°C can be used for modelling Radio Frequency Ablation of human uterine fibroids at a frequency of 460 kHz for temperatures from 37°C to 100°C.

Ion Propulsion Development Projects in US: Space Electric Rocket Test I to Deep Space 1

NASA Technical Reports Server (NTRS)

Sovey, James S.; Rawlin, Vincent K.; Patterson, Michael J.

2001-01-01

The historical background and characteristics of the experimental flights of ion propulsion systems and the major ground-based technology demonstrations are reviewed. The results of the first successful ion engine flight in 1964, Space Electric Rocket Test (SERT) I, which demonstrated ion beam neutralization, are discussed along with the extended operation of SERT II starting in 1970. These results together with the technologies employed on the early cesium engine flights, the applications technology satellite series, and the ground-test demonstrations, have provided the evolutionary path for the development of xenon ion thruster component technologies, control systems, and power circuit implementations. In the 1997-1999 period, the communication satellite flights using ion engine systems and the Deep Space 1 flight confirmed that these auxiliary and primary propulsion systems have advanced to a high level of flight readiness.

Depth-resolved ultra-violet spectroscopic photo current-voltage measurements for the analysis of AlGaN/GaN high electron mobility transistor epilayer deposited on Si

NASA Astrophysics Data System (ADS)

Ozden, Burcu; Yang, Chungman; Tong, Fei; Khanal, Min P.; Mirkhani, Vahid; Sk, Mobbassar Hassan; Ahyi, Ayayi Claude; Park, Minseo

2014-10-01

We have demonstrated that the depth-dependent defect distribution of the deep level traps in the AlGaN/GaN high electron mobility transistor (HEMT) epi-structures can be analyzed by using the depth-resolved ultra-violet (UV) spectroscopic photo current-voltage (IV) (DR-UV-SPIV). It is of great importance to analyze deep level defects in the AlGaN/GaN HEMT structure, since it is recognized that deep level defects are the main source for causing current collapse phenomena leading to reduced device reliability. The AlGaN/GaN HEMT epi-layers were grown on a 6 in. Si wafer by metal-organic chemical vapor deposition. The DR-UV-SPIV measurement was performed using a monochromatized UV light illumination from a Xe lamp. The key strength of the DR-UV-SPIV is its ability to provide information on the depth-dependent electrically active defect distribution along the epi-layer growth direction. The DR-UV-SPIV data showed variations in the depth-dependent defect distribution across the wafer. As a result, rapid feedback on the depth-dependent electrical homogeneity of the electrically active defect distribution in the AlGaN/GaN HEMT epi-structure grown on a Si wafer with minimal sample preparation can be elucidated from the DR-UV-SPIV in combination with our previously demonstrated spectroscopic photo-IV measurement with the sub-bandgap excitation.

Penetration of Nonstationary Ionospheric Electric Fields into Lower Atmospheric Layers in the Global Electric Circuit Model

NASA Astrophysics Data System (ADS)

Morozov, V. N.

2018-01-01

The problem of the penetration of nonstationary ionospheric electric fields into the lower atmospheric layers is considered based on the model of the global electric circuit in the Earth's atmosphere. For the equation of the electric field potential, a solution that takes into account exponential variation in the electrical conductivity with height has been obtained. Analysis of the solution made it possible to reveal three cases of the dependence of the solution on height. The first case (the case of high frequencies) corresponds to the Coulomb approximation, when the electrical conductivity of the atmosphere can be neglected. In the case of low frequencies (when the frequency of changes in the ionosphere potential is less than the quantity reciprocal to the time of electric relaxation of the atmosphere), a quasi-stationary regime, in which the variation in the electric potential of the atmosphere is determined by the electric conduction currents, occurs. In the third case, due to the increase in the electrical conductivity of the atmosphere, two spherical regions appear: with the Coulomb approximation in the lower region and conduction currents in the upper one. For these three cases, formulas for estimating the electric field strength near the Earth's surface have been obtained.

Reactive conductors for increased efficiency of exploding foil initiators and other detonators

DOEpatents

Morris, Christopher J.; Wilkins, Paul; May, Chadd; Zakar, Eugene

2015-05-05

Provided among other things are reactive energetic material systems used for conductors in detonators for increased efficiencies. According to an embodiment, a detonator may include: a conductor including at least two constituents including (i) an electrically conductive constituent, and (ii) an electrically non-conductive constituent, that when subjected to sufficient electrical energy, result in an exothermic reaction; and a flyer plate having a non-conductive surface in contact with said conductor. When the sufficient electrical energy is supplied to said conductor, rapid heating and vaporization of at least a portion of the conductor occurs so as to explosively drive at least a portion of the flyer plate away from said conductor. In an embodiment, a multilayer conductor may be formed of alternating layers of at least one electrically conductive layer, and at least one electrically non-conductive layer, that when subjected to sufficient electrical energy, result in an exothermic reaction.

Origin and assessment of deep groundwater inflow in the Ca' Lita landslide using hydrochemistry and in situ monitoring

NASA Astrophysics Data System (ADS)

Cervi, F.; Ronchetti, F.; Martinelli, G.; Bogaard, T. A.; Corsini, A.

2012-11-01

Changes in soil water content, groundwater flow and a rise in pore water pressure are well-known causal or triggering factors for hillslope instability. Rainfall and snowmelt are generally assumed as the main sources of groundwater recharge. This assumption neglects the role of deep water inflow in highly tectonized areas, a factor that can influence long-term pore-pressure regimes and play a role on local slope instability. This paper aims to assess the origin of groundwater in the Ca' Lita landslide (northern Italian Apennines) and to qualify and quantify the aliquot attributable to deep water inflow. The research is essentially based on in situ monitoring and hydrochemical analyses. It involved 5 yr of continuous monitoring of groundwater levels, electrical conductivity and temperature and with groundwater sampling followed by determination of major ions (Na+, K+, Mg2+, Ca2+, Cl-, HCO3-, SO42-), tracers (such as Btot and Sr2+), and isotopes (δ18O, δ2H and 3H). Leaching experiments on soil samples, hydrochemical modelling and water recharge estimation were also carried out. Results show that the groundwater balance in the Ca' Lita landslide must take into account an inflow of deep and highly mineralised Na-SO4 water (more than 9500 μS cm-1) with non-negligible amounts of Cl- (up to 800 mg l-1). The chemical and isotopic fingerprint of this water points to oilfield water hosted at large depths in the Apennine chain and that uprises through a regional fault line crossing the landslide area. It recharges the aquifer hosted in the bedrock underlying the sliding surface (at a rate of about 49 000-85 700 m3 yr-1) and it also partly recharges the landslide body. In both the aquifers, the hydrochemical imprint of deep water mixed with rainfall and snowmelt water was observed. This indicates a probable influence of deep water inflow on the mobility of the Ca' Lita landslide, a finding that could be applicable to other large landslides occurring in highly tectonized areas in the northern Apennines or in other mountain chains. The paper demonstrates that hydrochemistry should, therefore, be considered as a valuable investigation method to define hydrogeological limits and the groundwater sources in hillslope and to assess groundwater flow patterns in deep-seated landslides.

Development of electrical conductivity measurement technology for key plant physiological information using microneedle sensor

NASA Astrophysics Data System (ADS)

Jeon, Eunyong; Choi, Seungyul; Yeo, Kyung-Hwan; Park, Kyoung Sub; Rathod, Mitesh L.; Lee, Junghoon

2017-08-01

Impedance measurement is a widely used technique for monitoring ion species in various applications. In plant cultivation, the impedance system is used to measure the electrical conductivity (EC) of nutrient solutions. Recent research has shown that the quality and quantity of horticultural crops, e.g. tomato, can be optimized by controlling the salinity of nutrient solutions. However, understanding the detailed response of a plant to a nutrient solution is not possible until the fruit is fully grown or by sacrificing the stem. To overcome this issue, horticultural crop cultivation requires real-time monitoring of the EC inside the stem. Using this data, the growth model of a plant could be constructed, and the response of the plant to external environment determined. In this paper, we propose an implantable microneedle device equipped with a micro-patterned impedance measurement system for direct measurement of the EC inside the tomato stem. The fabrication process includes silicon-based steps such as microscale deposition, photolithography, and a deep etching process. Further, microscale fabrication enables all functional elements to fulfill the area budget and be very accurate with minimal plant invasion. A two-electrode geometry is used to match the measurement condition of the tomato stem. Real-time measurement of local sap condition inside the plant in which real-time data for tomato sap EC is obtained after calibration at various concentrations of standard solution demonstrate the efficacy of the proposed device.

Results of a magnetotelluric traverse across western Oregon: crustal resistivity structure and the subduction of the Juan de Fuca plate

NASA Astrophysics Data System (ADS)

Waff, Harve S.; Rygh, John T.; Livelybrooks, Dean W.; Clingman, William W.

1988-02-01

As part of project EMSLAB, we have collected and analysed wideband magnetotelluric data along an east-west transect in western Oregon. Preliminary modelling of the data using one-dimensional inversions based upon rotationally-invariant earth response functions was followed by finite-element two-dimensional modelling. The models produced indicate the presence of an electrical conductor beneath the Oregon Coast Range dipping eastward at 12-18° from a depth of 23-32 km. We believe that this conductor includes the thrust surface of the subducting Juan de Fuca plate and/or adjacent water-saturated rocks. Its high conductance (about 200 S) is thought to be due to one or more of the following mechanisms: (1) sediments subducted atop and with the Juan de Fuca plate, (2) saline fluids produced by dehydration of the former, or (3) seawater contained within subducted oceanic basalts. There is a distinct possibility that the high conductivity is due primarily to the presence of subducted sediments, in contrast with the notion that the subduction of young, buoyant lithosphere retards sediment subduction at this convergent margin. The conductive layer is overlain by relatively resistive rocks presumed to be accreted oceanic lithosphere. Model-determined resistivities for the upper part of the Coast Range section are in good agreement with deep well-log data. A strong electrical contrast appears in the determinant phase pseudosection between the Coast Range and the Willamette Valley suggesting a structural boundary between the two provinces. A surficial conductor is present in the valley to depths of 1-2 km and is due to alluvial fill. Induction arrow data show the geomagnetic coast effect and a smaller effect by the Willamette Valley alluvial fill.

All-photonic drying and sintering process via flash white light combined with deep-UV and near-infrared irradiation for highly conductive copper nano-ink

PubMed Central

Hwang, Hyun-Jun; Oh, Kyung-Hwan; Kim, Hak-Sung

2016-01-01

We developed an ultra-high speed photonic sintering method involving flash white light (FWL) combined with near infrared (NIR) and deep UV light irradiation to produce highly conductive copper nano-ink film. Flash white light irradiation energy and the power of NIR/deep UV were optimized to obtain high conductivity Cu films. Several microscopic and spectroscopic characterization techniques such as scanning electron microscopy (SEM), a x-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy were employed to characterize the Cu nano-films. Optimally sintered Cu nano-ink films produced using a deep UV-assisted flash white light sintering technique had the lowest resistivity (7.62 μΩ·cm), which was only 4.5-fold higher than that of bulk Cu film (1.68 μΩ•cm). PMID:26806215

All-photonic drying and sintering process via flash white light combined with deep-UV and near-infrared irradiation for highly conductive copper nano-ink.

PubMed

Hwang, Hyun-Jun; Oh, Kyung-Hwan; Kim, Hak-Sung

2016-01-25

We developed an ultra-high speed photonic sintering method involving flash white light (FWL) combined with near infrared (NIR) and deep UV light irradiation to produce highly conductive copper nano-ink film. Flash white light irradiation energy and the power of NIR/deep UV were optimized to obtain high conductivity Cu films. Several microscopic and spectroscopic characterization techniques such as scanning electron microscopy (SEM), a x-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy were employed to characterize the Cu nano-films. Optimally sintered Cu nano-ink films produced using a deep UV-assisted flash white light sintering technique had the lowest resistivity (7.62 μΩ·cm), which was only 4.5-fold higher than that of bulk Cu film (1.68 μΩ•cm).

Simultaneous recording of fluorescence and electrical signals by photometric patch electrode in deep brain regions in vivo

PubMed Central

Hirai, Yasuharu; Nishino, Eri

2015-01-01

Despite its widespread use, high-resolution imaging with multiphoton microscopy to record neuronal signals in vivo is limited to the surface of brain tissue because of limited light penetration. Moreover, most imaging studies do not simultaneously record electrical neural activity, which is, however, crucial to understanding brain function. Accordingly, we developed a photometric patch electrode (PME) to overcome the depth limitation of optical measurements and also enable the simultaneous recording of neural electrical responses in deep brain regions. The PME recoding system uses a patch electrode to excite a fluorescent dye and to measure the fluorescence signal as a light guide, to record electrical signal, and to apply chemicals to the recorded cells locally. The optical signal was analyzed by either a spectrometer of high light sensitivity or a photomultiplier tube depending on the kinetics of the responses. We used the PME in Oregon Green BAPTA-1 AM-loaded avian auditory nuclei in vivo to monitor calcium signals and electrical responses. We demonstrated distinct response patterns in three different nuclei of the ascending auditory pathway. On acoustic stimulation, a robust calcium fluorescence response occurred in auditory cortex (field L) neurons that outlasted the electrical response. In the auditory midbrain (inferior colliculus), both responses were transient. In the brain-stem cochlear nucleus magnocellularis, calcium response seemed to be effectively suppressed by the activity of metabotropic glutamate receptors. In conclusion, the PME provides a powerful tool to study brain function in vivo at a tissue depth inaccessible to conventional imaging devices. PMID:25761950

Simultaneous recording of fluorescence and electrical signals by photometric patch electrode in deep brain regions in vivo.

PubMed

Hirai, Yasuharu; Nishino, Eri; Ohmori, Harunori

2015-06-01

Despite its widespread use, high-resolution imaging with multiphoton microscopy to record neuronal signals in vivo is limited to the surface of brain tissue because of limited light penetration. Moreover, most imaging studies do not simultaneously record electrical neural activity, which is, however, crucial to understanding brain function. Accordingly, we developed a photometric patch electrode (PME) to overcome the depth limitation of optical measurements and also enable the simultaneous recording of neural electrical responses in deep brain regions. The PME recoding system uses a patch electrode to excite a fluorescent dye and to measure the fluorescence signal as a light guide, to record electrical signal, and to apply chemicals to the recorded cells locally. The optical signal was analyzed by either a spectrometer of high light sensitivity or a photomultiplier tube depending on the kinetics of the responses. We used the PME in Oregon Green BAPTA-1 AM-loaded avian auditory nuclei in vivo to monitor calcium signals and electrical responses. We demonstrated distinct response patterns in three different nuclei of the ascending auditory pathway. On acoustic stimulation, a robust calcium fluorescence response occurred in auditory cortex (field L) neurons that outlasted the electrical response. In the auditory midbrain (inferior colliculus), both responses were transient. In the brain-stem cochlear nucleus magnocellularis, calcium response seemed to be effectively suppressed by the activity of metabotropic glutamate receptors. In conclusion, the PME provides a powerful tool to study brain function in vivo at a tissue depth inaccessible to conventional imaging devices. Copyright © 2015 the American Physiological Society.

Electrochemical Device Comprising an Electrically-Conductive, Selectively-Permeable Membrane

NASA Technical Reports Server (NTRS)

Laicer, Castro S. T. (Inventor); Mittelsteadt, Cortney K. (Inventor); Harrison, Katherine E. (Inventor); McPheeters, Bryn M. (Inventor)

2017-01-01

An electrochemical device, such as a fuel cell or an electrolyzer. In one embodiment, the electrochemical device includes a membrane electrode assembly (MEA), an anodic gas diffusion medium in contact with the anode of the MEA, a cathodic gas diffusion medium in contact with the cathode, a first bipolar plate in contact with the anodic gas diffusion medium, and a second bipolar plate in contact with the cathodic gas diffusion medium. Each of the bipolar plates includes an electrically-conductive, non-porous, liquid-permeable, substantially gas-impermeable membrane in contact with its respective gas diffusion medium, the membrane including a solid polymer electrolyte and a non-particulate, electrically-conductive material, such as carbon nanotubes, carbon nanofibers, and/or metal nanowires. In addition, each bipolar plate also includes an electrically-conductive fluid chamber in contact with the electrically-conductive, selectively-permeable membrane and further includes a non-porous and electrically-conductive plate in contact with the fluid chamber.

Impurity effects on electrical conductivity of doped bilayer graphene in the presence of a bias voltage

NASA Astrophysics Data System (ADS)

E, Lotfi; H, Rezania; B, Arghavaninia; M, Yarmohammadi

2016-07-01

We address the electrical conductivity of bilayer graphene as a function of temperature, impurity concentration, and scattering strength in the presence of a finite bias voltage at finite doping, beginning with a description of the tight-binding model using the linear response theory and Green’s function approach. Our results show a linear behavior at high doping for the case of high bias voltage. The effects of electron doping on the electrical conductivity have been studied via changing the electronic chemical potential. We also discuss and analyze how the bias voltage affects the temperature behavior of the electrical conductivity. Finally, we study the behavior of the electrical conductivity as a function of the impurity concentration and scattering strength for different bias voltages and chemical potentials respectively. The electrical conductivity is found to be monotonically decreasing with impurity scattering strength due to the increased scattering among electrons at higher impurity scattering strength.

Bimodal electric tissue ablation (BETA): a study on ablation size when the anode is placed on the peritoneum and the liver.

PubMed

Tiong, Leong U; Finnie, John W; Field, John B; Maddern, Guy J

2012-07-01

In bimodal electric tissue ablation (BETA), the cathode of the DC circuit is attached to the radiofrequency (RF) electrode to increase the surrounding tissue hydration. This will delay tissue desiccation and allowing the ablation process to continue for a longer period of time before "roll-off" occurs, resulting in larger ablations compared with standard radiofrequency ablation (RFA). Previous research showed that attaching the anode to the skin using electrosurgical grounding pads would reduce the efficacy of BETA because of the high electrical resistivity of the skin. This study investigated the ablation size produced when the anode was attached to the peritoneum (BETA-peritoneum) and the liver (BETA-liver) respectively. The anode of the DC circuit in BETA was attached to the peritoneum and the liver in a pig model using ECG dots. In BETA, 9 V of DC was provided for 10 min, after which the radiofrequency generator were switched on and both electrical circuits allowed to run concurrently until "roll-off." The size of ablations produced was compared to when the anode attached to the skin (BETA-skin) and standard RFA, respectively. The sites of anode placement were examined for local tissue injury. The transverse diameters in BETA-peritoneum and BETA-liver were significantly larger compared with BETA-skin and standard RFA, respectively (P < 0.001). The axial diameter in the BETA-peritoneum and BETA-liver groups were also larger compared with the BETA-skin and RFA groups, although the differences did not reach statistical significance (P = 0.09). Hematoxylin and eosin (H and E) examination of the peritoneum and the liver where the anode was attached showed coagulation necrosis involving the superficial epithelium and the liver capsule, respectively. BETA can be used to treat larger liver tumors more effectively and may reduce the tumor recurrence rates compared with standard RFA. The efficacy of BETA depends on ensuring good electrical conductivity between the cathode and the anode of the DC circuit. Research so far has shown that BETA works best when the anode is placed deep to the skin as the stratum corneum consisted of a layer of a-nucleated cells, which have high electrical resistivity. The liver could be the ideal location to place the anode as it has excellent electrical conductivity, therefore ensuring maximum tissue hydration around the cathode to produce the largest ablations possible. Copyright © 2012 Elsevier Inc. All rights reserved.

GEOPHYSICS AND SITE CHARACTERIZATION AT THE HANFORD SITE THE SUCCESSFUL USE OF ELECTRICAL RESISTIVITY TO POSITION BOREHOLES TO DEFINE DEEP VADOSE ZONE CONTAMINATION - 11509

DOE Office of Scientific and Technical Information (OSTI.GOV)

GANDER MJ; LEARY KD; LEVITT MT

2011-01-14

Historic boreholes confirmed the presence of nitrate and radionuclide contaminants at various intervals throughout a more than 60 m (200 ft) thick vadose zone, and a 2010 electrical resistivity survey mapped the known contamination and indicated areas of similar contaminants, both laterally and at depth; therefore, electrical resistivity mapping can be used to more accurately locate characterization boreholes. At the Hanford Nuclear Reservation in eastern Washington, production of uranium and plutonium resulted in the planned release of large quantities of contaminated wastewater to unlined excavations (cribs). From 1952 until 1960, the 216-U-8 Crib received approximately 379,000,000 L (100,000,000 gal) ofmore » wastewater containing 25,500 kg (56,218 lb) uranium; 1,029,000 kg (1,013 tons) of nitrate; 2.7 Ci of technetium-99; and other fission products including strontium-90 and cesium-137. The 216-U-8 Crib reportedly holds the largest inventory of waste uranium of any crib on the Hanford Site. Electrical resistivity is a geophysical technique capable of identifying contrasting physical properties; specifically, electrically conductive material, relative to resistive native soil, can be mapped in the subsurface. At the 216-U-8 Crib, high nitrate concentrations (from the release of nitric acid [HNO{sub 3}] and associated uranium and other fission products) were detected in 1994 and 2004 boreholes at various depths, such as at the base of the Crib at 9 m (30 ft) below ground surface (bgs) and sporadically to depths in excess of 60 m (200 ft) bgs. These contaminant concentrations were directly correlative with the presence of observed low electrical resistivity responses delineated during the summer 2010 geophysical survey. Based on this correlation and the recently completed mapping of the electrically conductive material, additional boreholes are planned for early 2011 to identify nitrate and radionuclide contamination: (a) throughout the entire vertical length of the vadose zone (i.e., 79 m [260 ft] bgs) within the footprint of the Crib, and (b) 15 to 30 m (50 to 100 ft) east of the Crib footprint, where contaminants are inferred to have migrated through relatively permeable soils. Confirmation of the presence of contamination in historic boreholes correlates well with mapping from the 2010 survey, and serves as a basis to site future characterization boreholes that will likely intersect contamination both laterally and at depth.« less

Downhole data transmission system

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S; Dahlgren, Scott; Fox, Joe

2006-06-20

A system for transmitting data through a string of downhole components. In one aspect, the system includes first and second magnetically conductive, electrically insulating elements at both ends of the component. Each element includes a first U-shaped trough with a bottom, first and second sides and an opening between the two sides. Electrically conducting coils are located in each trough. An electrical conductor connects the coils in each component. In operation, a varying current applied to a first coil in one component generates a varying magnetic field in the first magnetically conductive, electrically insulating element, which varying magnetic field is conducted to and thereby produces a varying magnetic field in the second magnetically conductive, electrically insulating element of a connected component, which magnetic field thereby generates a varying electrical current in the second coil in the connected component.

Downhole Data Transmission System

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David; Dahlgren, Scott; Fox, Joe

2003-12-30

A system for transmitting data through a string of downhole components. In one aspect, the system includes first and second magnetically conductive, electrically insulating elements at both ends of the component. Each element includes a first U-shaped trough with a bottom, first and second sides and an opening between the two sides. Electrically conducting coils are located in each trough. An electrical conductor connects the coils in each component. In operation, a varying current applied to a first coil in one component generates a varying magnetic field in the first magnetically conductive, electrically insulating element, which varying magnetic field is conducted to and thereby produces a varying magnetic field in the second magnetically conductive, electrically insulating element of a connected component, which magnetic field thereby generates a varying electrical current in the second coil in the connected component.

Ground geophysical study of the Buckeye mine tailings, Boulder watershed, Montana

USGS Publications Warehouse

McDougal, Robert R.; Smith, Bruce D.

2000-01-01

The Buckeye mine site is located in the Boulder River watershed along Basin Creek, in northern Jefferson County, Montana. This project is part of the Boulder River watershed Abandoned Mine Lands Initiative, and is a collaborative effort between the U.S. Geological Survey and Bureau of Land Management in the U.S. Department of the Interior, and the U.S. Forest Service in the U.S. Department of Agriculture. The site includes a large flotation milltailing deposit, which extends to the stream and meadows below the mine. These tailings contain elevated levels of metals, such as silver, cadmium, copper, lead, and zinc. Metal-rich fluvial tailings containing these metals, are possible sources of ground and surface water contamination. Geophysical methods were used to characterize the sediments at the Buckeye mine site. Ground geophysical surveys, including electromagnetics, DC resistivity, and total field magnetic methods, were used to delineate anomalies that probably correlate with subsurface metal contamination. Subsurface conductivity was mapped using EM-31 and EM-34 terrain conductivity measuring systems. The conductivity maps represent variation of concentration of dissolved solids in the subsurface from a few meters, to an approximate depth of 30 meters. Conductive sulfides several centimeters thick were encountered in a shallow trench, dug in an area of very high conductivity, at a depth of approximately 1 to1.5 meters. Laboratory measurements of samples of the sulfide layers show the conductivity is on the order of 1000 millisiemens. DC resistivity soundings were used to quantify subsurface conductivity variations and to estimate the depth to bedrock. Total field magnetic measurements were used to identify magnetic metals in the subsurface. The EM surveys identified several areas of relatively high conductivity and detected a conductive plume extending to the southwest, toward the stream. This plume correlates well with the potentiometric surface and direction of ground water flow, and with water quality data from monitoring wells in and around the tailings. The electrical geophysical data suggests there has been vertical migration of high dissolved solids. A DC sounding made on a nearby granite outcrop to the north of the mine showed that the shallow conductivity is on the order of 5 millisiemens/m. Granite underlying the mine tailings, with similar electrical properties as the outcropping area, may be more than 30 meters deep.

3D imaging of soil apparent electrical conductivity from VERIS data using a 1D spatially constrained inversion algorithm

NASA Astrophysics Data System (ADS)

Jesús Moral García, Francisco; Rebollo Castillo, Francisco Javier; Monteiro Santos, Fernando

2016-04-01

Maps of apparent electrical conductivity of the soil are commonly used in precision agriculture to indirectly characterize some important properties like salinity, water, and clay content. Traditionally, these studies are made through an empirical relationship between apparent electrical conductivity and properties measured in soil samples collected at a few locations in the experimental area and at a few selected depths. Recently, some authors have used not the apparent conductivity values but the soil bulk conductivity (in 2D or 3D) calculated from measured apparent electrical conductivity through the application of an inversion method. All the published works used data collected with electromagnetic (EM) instruments. We present a new software to invert the apparent electrical conductivity data collected with VERIS 3100 and 3150 (or the more recent version with three pairs of electrodes) using the 1D spatially constrained inversion method (1D SCI). The software allows the calculation of the distribution of the bulk electrical conductivity in the survey area till a depth of 1 m. The algorithm is applied to experimental data and correlations with clay and water content have been established using soil samples collected at some boreholes. Keywords: Digital soil mapping; inversion modelling; VERIS; soil apparent electrical conductivity.

Enhanced mechanical, thermal, and electric properties of graphene aerogels via supercritical ethanol drying and high-temperature thermal reduction.

PubMed

Cheng, Yehong; Zhou, Shanbao; Hu, Ping; Zhao, Guangdong; Li, Yongxia; Zhang, Xinghong; Han, Wenbo

2017-05-03

Graphene aerogels with high surface areas, ultra-low densities and thermal conductivities have been prepared to exploit their wide applications from pollution adsorption to energy storage, supercapacitor, and thermal insulation. However, the low mechanical properties, poor thermal stability and electric conductivity restrict these aerogels' applications. In this paper, we prepared mechanically strong graphene aerogels with large BET surface areas, low thermal conductivities, high thermal stability and electric conductivities via hydrothermal reduction and supercritical ethanol drying. Annealing at 1500 °C resulted in slightly increased thermal conductivity and further improvement in mechanical properties, oxidation temperature and electric conductivity of the graphene aerogel. The large BET surface areas, together with strong mechanical properties, low thermal conductivities, high thermal stability and electrical conductivities made these graphene aerogels feasible candidates for use in a number of fields covering from batteries to sensors, electrodes, lightweight conductor and insulation materials.

Differential and directional effects of perfusion on electrical and thermal conductivities in liver.

PubMed

Podhajsky, Ronald J; Yi, Ming; Mahajan, Roop L

2009-01-01

Two different measurement probes--an electrical probe and a thermal conductivity probe--were designed, fabricated, calibrated, and used in experimental studies on a pig liver model that was designed to control perfusion rates. These probes were fabricated by photolithography and mounted in 1.5-mm diameter catheters. We measured the local impedance and thermal conductivity, respectively, of the artificially perfused liver at different flow rates and, by rotating the probes, in different directions. The results show that both the local electrical conductivity and the thermal conductivity varied location to location, that thermal conductivity increased with decreased distance to large blood vessels, and that significant directional differences exist in both electrical and thermal conductivities. Measurements at different perfusion rates demonstrated that both the local electrical and local thermal conductivities increased linearly with the square root of perfusion rate. These correlations may be of great value to many energy-based biomedical applications.

Deep Borehole Field Test Research Activities at LBNL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dobson, Patrick; Tsang, Chin-Fu; Kneafsey, Timothy

The goal of the U.S. Department of Energy Used Fuel Disposition’s (UFD) Deep Borehole Field Test is to drill two 5 km large-diameter boreholes: a characterization borehole with a bottom-hole diameter of 8.5 inches and a field test borehole with a bottom-hole diameter of 17 inches. These boreholes will be used to demonstrate the ability to drill such holes in crystalline rocks, effectively characterize the bedrock repository system using geophysical, geochemical, and hydrological techniques, and emplace and retrieve test waste packages. These studies will be used to test the deep borehole disposal concept, which requires a hydrologically isolated environment characterizedmore » by low permeability, stable fluid density, reducing fluid chemistry conditions, and an effective borehole seal. During FY16, Lawrence Berkeley National Laboratory scientists conducted a number of research studies to support the UFD Deep Borehole Field Test effort. This work included providing supporting data for the Los Alamos National Laboratory geologic framework model for the proposed deep borehole site, conducting an analog study using an extensive suite of geoscience data and samples from a deep (2.5 km) research borehole in Sweden, conducting laboratory experiments and coupled process modeling related to borehole seals, and developing a suite of potential techniques that could be applied to the characterization and monitoring of the deep borehole environment. The results of these studies are presented in this report.« less

Recent Advances in Nuclear Powered Electric Propulsion for Space Exploration

NASA Technical Reports Server (NTRS)

Cassady, R. Joseph; Frisbee, Robert H.; Gilland, James H.; Houts, Michael G.; LaPointe, Michael R.; Maresse-Reading, Colleen M.; Oleson, Steven R.; Polk, James E.; Russell, Derrek; Sengupta, Anita

2007-01-01

Nuclear and radioisotope powered electric thrusters are being developed as primary in-space propulsion systems for potential future robotic and piloted space missions. Possible applications for high power nuclear electric propulsion include orbit raising and maneuvering of large space platforms, lunar and Mars cargo transport, asteroid rendezvous and sample return, and robotic and piloted planetary missions, while lower power radioisotope electric propulsion could significantly enhance or enable some future robotic deep space science missions. This paper provides an overview of recent U.S. high power electric thruster research programs, describing the operating principles, challenges, and status of each technology. Mission analysis is presented that compares the benefits and performance of each thruster type for high priority NASA missions. The status of space nuclear power systems for high power electric propulsion is presented. The paper concludes with a discussion of power and thruster development strategies for future radioisotope electric propulsion systems,

Capillary zone electrophoresis-mass spectrometer interface

DOEpatents

D`Silva, A.

1996-08-06

A device for providing equal electrical potential between two loci unconnected by solid or liquid electrical conductors is provided. The device comprises a first electrical conducting terminal, a second electrical conducting terminal connected to the first terminal by a rigid dielectric structure, and an electrically conducting gas contacting the first and second terminals. This device is particularly suitable for application in the electrospray ionization interface between a capillary zone electrophoresis apparatus and a mass spectrometer. 1 fig.

A percolation approach to study the high electric field effect on electrical conductivity of insulating polymer

NASA Astrophysics Data System (ADS)

Benallou, Amina; Hadri, Baghdad; Martinez-Vega, Juan; El Islam Boukortt, Nour

2018-04-01

The effect of percolation threshold on the behaviour of electrical conductivity at high electric field of insulating polymers has been briefly investigated in literature. Sometimes the dead ends links are not taken into account in the study of the electric field effect on the electrical properties. In this work, we present a theoretical framework and Monte Carlo simulation of the behaviour of the electric conductivity at high electric field based on the percolation theory using the traps energies levels which are distributed according to distribution law (uniform, Gaussian, and power-law). When a solid insulating material is subjected to a high electric field, and during trapping mechanism the dead ends of traps affect with decreasing the electric conductivity according to the traps energies levels, the correlation length of the clusters, the length of the dead ends, and the concentration of the accessible positions for the electrons. A reasonably good agreement is obtained between simulation results and the theoretical framework.

A percolation model for electrical conduction in wood with implications for wood-water relations

Treesearch

Samuel L. Zelinka; Samuel V. Glass; Donald S. Stone

2008-01-01

The first models used to describe electrical conduction in cellulosic materials involved conduction pathways through free water. These models were abandoned in the middle of the 20th century. This article re-evaluates the theory of conduction in wood by using a percolation model that describes electrical conduction in terms of overlapping paths of loosely bound or...

Seasonal performance for Heat pump with vertical ground heat exchanger in Riga

NASA Astrophysics Data System (ADS)

Jaundālders, S.; Stanka, P.; Rusovs, D.

2017-10-01

Experimental measurements of Seasonal Coefficient of Performance (SCOP) for heating of 160 m2 household in Riga were conducted for operation of brine-water heat pump with vertical ground heat exchangers (GHE). Data regarding heat and electrical power consumption were recorded during three-year period from 2013 to 2016. Vapor compression heat pump has heat energy output of 8 kW. GHE consists of three boreholes. Each borehole is 60 m deep. Data regarding brine temperature for borehole input and output were presented and discussed. As far as house had floor heating, there were presented data about COP for B0/W35 and its dependence from room and outdoor temperature during heating season. Empirical equation was created. Average heat energy consumption during one year for heating was 72 kWh/m2 measured by heat meter. Detected primary energy consumption (electrical energy from grid) was 21 kWh/m2 which resulted in SCOP=3.8. These data were compared with SCOP for air-to-water heat pump in Latvia and available configuration software for heat pumps operation. Good agreement between calculated performance and reported experimental data were founded.

Vertical Soil Profiling Using a Galvanic Contact Resistivity Scanning Approach

PubMed Central

Pan, Luan; Adamchuk, Viacheslav I.; Prasher, Shiv; Gebbers, Robin; Taylor, Richard S.; Dabas, Michel

2014-01-01

Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep) soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument. PMID:25057135

Charged Water Droplets can Melt Metallic Electrodes

NASA Astrophysics Data System (ADS)

Elton, Eric; Rosenberg, Ethan; Ristenpart, William

2016-11-01

A water drop, when immersed in an insulating fluid, acquires charge when it contacts an energized electrode. Provided the electric field is strong enough, the drop will move away to the opposite electrode, acquire the opposite charge, and repeat the process, effectively 'bouncing' back and forth between the electrodes. A key implicit assumption, dating back to Maxwell, has been that the electrode remains unaltered by the charging process. Here we demonstrate that the electrode is physically deformed during each charge transfer event with an individual water droplet or other conducting object. We used optical, electron, and atomic force microscopy to characterize a variety of different metallic electrodes before and after drops were electrically bounced on them. Although the electrodes appear unchanged to the naked eye, the microscopy reveals that each charge transfer event yielded a crater approximately 1 micron wide and 50 nm deep, with the exact dimensions proportional to the applied field strength. We present evidence that the craters are formed by localized melting of the electrodes via Joule heating in the metal and concurrent dielectric breakdown of the surrounding fluid, suggesting that the electrode locally achieves temperatures exceeding 3400°C. Present address: Dept. Materials Sci. Engineering, MIT.

A Novel Cu-10Zn-1.5Ni-0.34Si Alloy with Excellent Mechanical Property Through Precipitation Hardening

NASA Astrophysics Data System (ADS)

Chen, Wei; Wang, Mingpu; Li, Zhou; Dong, Qiyi; Jia, Yanlin; Xiao, Zhu; Zhang, Rui; Yu, Hongchun

2016-11-01

A novel Cu-10Zn-1.5Ni-0.34Si alloy was designed to replace the expensive tin-phosphor bronze in this paper. The alloy had better comprehensive mechanical properties than traditional C5191 alloy. The aged Cu-10Zn-1.5Ni-0.34Si alloy had a hardness of 220 HV, electrical conductivity of 28.5% IACS, tensile strength of 650 MPa, yield strength of 575 MPa and elongation of 13%. Ni2Si precipitates formed during aging, and the crystal orientation relationship between matrix and precipitates was: (001)α//(001)δ, and [110]α//[100]δ. Ductile fracture surface with deep cavities was found in the alloy. Solid solution strengthening, deformation strengthening and precipitation strengthening were found to be core strengthening mechanisms in the alloy.

A surface-potential-based drain current compact model for a-InGaZnO thin-film transistors in Non-Degenerate conduction regime

NASA Astrophysics Data System (ADS)

Yu, Fei; Ma, Xiaoyu; Deng, Wanling; Liou, Juin J.; Huang, Junkai

2017-11-01

A physics-based drain current compact model for amorphous InGaZnO (a-InGaZnO) thin-film transistors (TFTs) is proposed. As a key feature, the surface potential model accounts for both exponential tail and deep trap densities of states, which are essential to describe a-InGaZnO TFT electrical characteristics. The surface potential is solved explicitly without the process of amendment and suitable for circuit simulations. Furthermore, based on the surface potential, an explicit closed-form expression of the drain current is developed. For the cases of the different operational voltages, surface potential and drain current are verified by numerical results and experimental data, respectively. As a result, our model can predict DC characteristics of a-InGaZnO TFTs.

Imaging hydrothermal systems at Furnas caldera (Azores, Portugal): Insights from Audio-Magnetotelluric data

NASA Astrophysics Data System (ADS)

Hogg, Colin; Kiyan, Duygu; Rath, Volker; Byrdina, Svetlana; Vandemeulebrouck, Jean; Silva, Catarina; Viveiros, Maria FB; Ferreira, Teresa

2016-04-01

The Furnas volcano is the eastern-most of the three active central volcanoes of Sao Miguel Island. The main caldera formed about 30 ka BP, followed by a younger eruption at 10-12 ka BP, which forms the steep topography of more than 200 m in the measuring area. It contains several very young eruptive centers, and a shallow caldera lake. Tectonic features of varying directions have been identified in the Caldera and its vicinity. In the northern part of the caldera, containing the fumarole field of Caldeiras das Furnas, a detailed map of surface CO2 emissions was recently made available. In 2015, a pilot survey of 13 AudioMagnetoTelluric soundings (AMT) and Electrical Resistivity Tomography (ERT) data were collected along two profiles in the eastern part of Furnas caldera in order to image the electrical conductivity of the subsurface. The data quality achieved by both techniques is extraordinary and first results indicate a general correlation between regions of elevated conductivity and the mapped surface CO2 emissions, suggesting that they may both be caused by the presence hydrothermal fluids. Tensor decomposition analysis using the Groom-Bailey approach produce a generalised geo-electric strike direction, 72deg East of North, for the AMT data compared to the surface geological strike derived from the major mapped fault crossing the profiles of 105deg. An analysis of the real induction arrows at certain frequencies (at depths greater than 350 m) infer that an extended conductor at depth does not exactly correspond to the degassing structures at the surface and extends outside the area of investigation. The geometry of the most conductive regions with electrical conductivities less then1 Ώm found at various depths differ from what was expected from earlier geologic and tectonic studies and possibly may not be directly related to the mapped fault systems at the surface. On the eastern profile, which seemed to be more appropriate for 2-D modelling with 72deg strike angle, a deep structure starting north of the major mapped fault crossing this profile can be found. It extends far to the south, with a top of approximately 150 m below the surface at the northern limit. A deeper conductive structure (top at about 300 m) is emerging at the southern end of the profile, though not fully resolved by the existing data. This work will focus on the processing, analysis and preliminary modelling results of the AMT data. A joint interpretation of the AMT results together with the ERT data covering the shallow regime with much higher resolution will be presented.

Convection Electric Field Observations by THEMIS and the Van Allen Probes

NASA Astrophysics Data System (ADS)

Califf, S.; Li, X.; Bonnell, J. W.; Wygant, J. R.; Malaspina, D.; Hartinger, M.; Thaller, S. A.

2013-12-01

We present direct electric field measurements made by THEMIS and the Van Allen Probes in the inner magnetosphere, focusing on the large-scale, near-DC convection electric field. The convection electric field drives plasma Earthward from the tail into the inner magnetosphere, playing a critical role in forming the ring current. Although it is normally shielded deep inside the magnetosphere, during storm times this large-scale electric field can penetrate to low L values (L < 3), eroding the plasmasphere and also providing a mechanism for ~100 keV electron injection into the slot region and inner radiation belt. The relationship of the convection electric field with the plasmasphere is also important for understanding the dynamic outer radiation belt, as the plasmapause boundary has been strongly correlated with the dynamic variation of the outer radiation belt electrons.

Electrically conductive material

DOEpatents

Singh, J.P.; Bosak, A.L.; McPheeters, C.C.; Dees, D.W.

1993-09-07

An electrically conductive material is described for use in solid oxide fuel cells, electrochemical sensors for combustion exhaust, and various other applications possesses increased fracture toughness over available materials, while affording the same electrical conductivity. One embodiment of the sintered electrically conductive material consists essentially of cubic ZrO[sub 2] as a matrix and 6-19 wt. % monoclinic ZrO[sub 2] formed from particles having an average size equal to or greater than about 0.23 microns. Another embodiment of the electrically conductive material consists essentially at cubic ZrO[sub 2] as a matrix and 10-30 wt. % partially stabilized zirconia (PSZ) formed from particles having an average size of approximately 3 microns. 8 figures.

Contribution of electromagnetic and tomographic technique to the study of the impact of salinity in soils of the experimental station of Al Ain Atti (Errachidia, Morocco)

NASA Astrophysics Data System (ADS)

Benamara, A.; El Harnafi, M.; Ammar, A.

2017-03-01

Soil salinity is widespread particularly in arid areas. Much work has been done to remedy this natural contamination and make them more favorable to receive experimental soil of vegetation adapted to grow in these contrasting environments of scarce water resources. Over the 80 years, Morocco has experienced excessive dryness whose effects have been severely felt in the region of Errachidia. The depletion of the Quaternary alluvial aquifer has required the exploitation of deep reservoirs. In order to optimize the use of salt water in arid, the Institute of Agricultural Research tested soil experimenting three plant species; the Triplex, Acacia and Cypress. This experiment was not only economic objectives; increasing agricultural yields and production, but also reduce the impact of desertification in this region. So these are environmental reasons which have led researchers to realize this experiment whose purpose is to examine the ability of these plants to grow and adapt to irrigation by saline water from the deep aquifer in place. The experimental site is located on the left bank of the national road to Erfoud (Errachidia). In its entirety, the redesigned covering about 10 hectares. The studies that have been conducted mainly concerned pedogenetic analyzes and observations the development height of the plantation tested, regardless of the experimental ground heterogeneity. This is why we undertook a geophysical survey which aims to provide information on the quality of the tested soils and accumulation of salinity at different depths of the experimental ground. To achieve our goal, we used the technique of electrical and electromagnetic investigation in order to identify the main lines of a possible spatial heterogeneity. Recall that the work of OKAY (2010) on an experiment coring by examining the evolution of the newly formed fracturing have proved that the result of resistivity measurement is correlated with that of the chargeability. The electrical resistivity is closely related to the concentration of mineral particles. Characterization studies at the La Ronde tailings mine (Agnico-Eagle Ltd, in Abitibi), showed quite encouraging results (Campos, 2004; Anterrieu, 2006). Since it is a salt-bearing areas (highly conductive) and given that the induced polarization is very sensitive to the ground conductivity; by measurement of residual potential, so we took measures chargeability tomography, the result is compared to the resistivity measured at different soils (control and irrigated), which will better clarify the impact of salinity on the quality of the disturbed soil. Indeed, the chargeability response it possible to characterize the different irrigated soils and its variation is attributed not only to the effect of saline irrigation but also the existence of an heterogeneity of the original ground. Prospecting in electrical tomography has displayed vertically and horizontally anomalies existing within the experimental site of the station of Ain Al Atti, it showed that: - accumulation of salinity becomes wider going from the control ground to that of Acacias. - surveyed the ground at least appear more homogeneous in surface, but their conductivity varies in depth. - salinity origin and the concretion formed on the surface greatly influenced chargeability and resistivity measured on the different experimental soils.

All diamond self-aligned thin film transistor

DOEpatents

Gerbi, Jennifer [Champaign, IL

2008-07-01

A substantially all diamond transistor with an electrically insulating substrate, an electrically conductive diamond layer on the substrate, and a source and a drain contact on the electrically conductive diamond layer. An electrically insulating diamond layer is in contact with the electrically conductive diamond layer, and a gate contact is on the electrically insulating diamond layer. The diamond layers may be homoepitaxial, polycrystalline, nanocrystalline or ultrananocrystalline in various combinations.A method of making a substantially all diamond self-aligned gate transistor is disclosed in which seeding and patterning can be avoided or minimized, if desired.

The DESMEX Project - Deep Electromagnetic Sounding for Mineral EXploration

NASA Astrophysics Data System (ADS)

Meyer, U.; Becken, M.; Stolz, R.; Nittinger, C.; Cherevatova, M.; Siemon, B.; Martin, T.; Petersen, H.; Steuer, A.

2017-12-01

The DESMEX project (Deep Electromagnetic Sounding for Mineral Exploration) aims to develop independent semi-airborne frequency domain systems for mineral exploration down to depths of 1 km and deeper. Two different helicopter-towed systems are being designed and tested using source installations on ground. One system uses among other equipment conventional three axis induction coils, a 3D-fluxgate and a high precision inertial motion unit. The use of the two different magnetometers allows to record data in a broad frequency range from 1 Hz to 10 kHz. The second system uses a newly developed SQUID-based sensing system of a similar frequency range and a self made inertial motion unit. Horizontal electric dipole transmitters provided by the Leibniz Institute for Applied Geophysics in Hannover and the Institute of Geophysics and Meteorology of the University in Cologne are used as ground based sources. First system tests showed a good performance of both systems with general noise levels below 50 pT/root(Hz). Test flights above the common survey area proved that the desired depth of investigation can be achieved and that the data is consistent with the subsurface conductivity structures. In order to verify the data acquired from the newly developed system at shallow depths and to provide a better starting model for later inversion calculations helicopter borne frequency domain electromagnetics has been acquired and fully processed over the test site Schleiz - Greiz in Germany. To further relate the subsurface conductivity models to the subsurface geology and mineralogy, petrophysical investigations have been performed on rock samples from the site of investigation and analogue samples.

Implications of ground water chemistry and flow patterns for earthquake studies.

PubMed

Guangcai, Wang; Zuochen, Zhang; Min, Wang; Cravotta, Charles A; Chenglong, Liu

2005-01-01

Ground water can facilitate earthquake development and respond physically and chemically to tectonism. Thus, an understanding of ground water circulation in seismically active regions is important for earthquake prediction. To investigate the roles of ground water in the development and prediction of earthquakes, geological and hydrogeological monitoring was conducted in a seismogenic area in the Yanhuai Basin, China. This study used isotopic and hydrogeochemical methods to characterize ground water samples from six hot springs and two cold springs. The hydrochemical data and associated geological and geophysical data were used to identify possible relations between ground water circulation and seismically active structural features. The data for delta18O, deltaD, tritium, and 14C indicate ground water from hot springs is of meteoric origin with subsurface residence times of 50 to 30,320 years. The reservoir temperature and circulation depths of the hot ground water are 57 degrees C to 160 degrees C and 1600 to 5000 m, respectively, as estimated by quartz and chalcedony geothermometers and the geothermal gradient. Various possible origins of noble gases dissolved in the ground water also were evaluated, indicating mantle and deep crust sources consistent with tectonically active segments. A hard intercalated stratum, where small to moderate earthquakes frequently originate, is present between a deep (10 to 20 km), high-electrical conductivity layer and the zone of active ground water circulation. The ground water anomalies are closely related to the structural peculiarity of each monitoring point. These results could have implications for ground water and seismic studies in other seismogenic areas.

Implications of ground water chemistry and flow patterns for earthquake studies

USGS Publications Warehouse

Guangcai, W.; Zuochen, Z.; Min, W.; Cravotta, C.A.; Chenglong, L.

2005-01-01

Ground water can facilitate earthquake development and respond physically and chemically to tectonism. Thus, an understanding of ground water circulation in seismically active regions is important for earthquake prediction. To investigate the roles of ground water in the development and prediction of earthquakes, geological and hydrogeological monitoring was conducted in a seismogenic area in the Yanhuai Basin, China. This study used isotopic and hydrogeochemical methods to characterize ground water samples from six hot springs and two cold springs. The hydrochemical data and associated geological and geophysical data were used to identify possible relations between ground water circulation and seismically active structural features. The data for ??18O, ??D, tritium, and 14C indicate ground water from hot springs is of meteoric origin with subsurface residence times of 50 to 30,320 years. The reservoir temperature and circulation depths of the hot ground water are 57??C to 160??C and 1600 to 5000 m, respectively, as estimated by quartz and chalcedony geothermometers and the geothermal gradient. Various possible origins of noble gases dissolved in the ground water also were evaluated, indicating mantle and deep crust sources consistent with tectonically active segments. A hard intercalated stratum, where small to moderate earthquakes frequently originate, is present between a deep (10 to 20 km), high-electrical conductivity layer and the zone of active ground water circulation. The ground water anomalies are closely related to the structural peculiarity of each monitoring point. These results could have implications for ground water and seismic studies in other seismogenic areas. Copyright ?? 2005 National Ground Water Association.

Perforation patterned electrical interconnects

DOEpatents

Frey, Jonathan

2014-01-28

This disclosure describes systems and methods for increasing the usable surface area of electrical contacts within a device, such as a thin film solid state device, through the implementation of electrically conductive interconnects. Embodiments described herein include the use of a plurality of electrically conductive interconnects that penetrate through a top contact layer, through one or more multiple layers, and into a bottom contact layer. The plurality of conductive interconnects may form horizontal and vertical cross-sectional patterns. The use of lasers to form the plurality of electrically conductive interconnects from reflowed layer material further aids in the manufacturing process of a device.

Capacitor discharge process for welding braided cable

DOEpatents

Wilson, Rick D.

1995-01-01

A capacitor discharge process for welding a braided cable formed from a plurality of individual cable strands to a solid metallic electrically conductive member comprises the steps of: (a) preparing the electrically conductive member for welding by bevelling one of its end portions while leaving an ignition projection extending outwardly from the apex of the bevel; (b) clamping the electrically conductive member in a cathode fixture; (c) connecting the electrically conductive member clamped in the cathode fixture to a capacitor bank capable of being charged to a preselected voltage value; (d) preparing the braided cable for welding by wrapping one of its end portions with a metallic sheet to form a retaining ring operable to maintain the individual strands of the braided cable in fixed position within the retaining ring; (e) clamping the braided cable and the retaining ring as a unit in an anode fixture so that the wrapped end portion of the braided cable faces the ignition projection of the electrically conductive member; and (f) moving the cathode fixture towards the anode fixture until the ignition projection of the electrically conductive member contacts the end portion of the braided cable thereby allowing the capacitor bank to discharge through the electrically conductive member and through the braided cable and causing the electrically conductive member to be welded to the braided cable via capacitor discharge action.

Simplified Calculation of the Electrical Conductivity of Composites with Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Ivanov, S. G.; Aniskevich, A.; Kulakov, V.

2018-03-01

The electrical conductivity of two groups of polymer nanocomposites filled with the same NC7000 carbon nanotubes (CNTs) beyond the percolation threshold is described with the help of simple formulas. Different manufacturing process of the nanocomposites led to different CNT network structures, and, as a consequence, their electrical conductivity, at the same CNT volume, differed by two orders of magnitude. The relation between the electrical conductivity and the volume content of CNTs of the first group of composites (with a higher electrical conductivity) is described assuming that the CNT network structure is close to a statistically homogeneous one. The formula for this case, derived on the basis of a self-consistent model, includes only two parameters: the effective longitudinal electrical conductivity of CNT and the percolation threshold (the critical value of CNT volume content). These parameters were determined from two experimental points of electrical conductivity as a function of the volume fraction of CNTs. The second group of nanocomposites had a pronounced agglomerative structure, which was confirmed by microscopy data. To describe the low electrical conductivity of this group of nanocomposites, a formula based on known models of micromechanics is proposed. Two parameters of this formula were determined from experimental data of the first group, but the other two — of the second group of nanocomposites. A comparison of calculation and experimental relations confirmed the practical expediency of using the approach described.

Indicators: Conductivity

EPA Pesticide Factsheets

Conductivity is a measure of the ability of water to pass an electrical current. Because dissolved salts and other inorganic chemicals conduct electrical current, conductivity increases as salinity increases.

Electrical foot stimulation and implications for the prevention of venous thromboembolic disease.

PubMed

Kaplan, Robert E; Czyrny, James J; Fung, Tat S; Unsworth, John D; Hirsh, Jack

2002-08-01

Venous stasis caused by immobility is an important risk factor for deep vein thrombosis following surgery and lower limb trauma, in bed-ridden medical patients, and in high-risk long distance air travelers. A safe and convenient method for reducing venous stasis would be useful in patients while in hospital and after discharge during their rehabilitation. 49 healthy subjects aged 51-76 were seated for 4 hours during which they received mild electrical stimulation of the calf, or sole of the foot (plantar muscles). Popliteal and femoral venous blood flow velocities were measured via doppler ultrasound. The non-stimulated lower extremity served as the simultaneous control. Subjects completed a questionnaire regarding their acceptance and tolerance of the electrical stimulation. There was a significant increase in venous femoral and popliteal blood flow for both calf (p < 0.035, p < 0.003), and plantar muscles (p < 0.0001, p < 0.009) on the stimulated side compared to the unstimulated side. The magnitude of the effect was similar for calf and plantar muscle stimulation. Subjects did not find the experience uncomfortable, and would use an electrical stimulator if told by their physician that they were at risk for developing blood clots. Mild electrical stimulation of the feet, as well as the calf, is a safe effective and convenient method for counteracting venous stasis and therefore has the potential to reduce the risk of deep vein thrombosis and pulmonary embolism for subjects who are immobilized.

Method and Apparatus for Obtaining a Precision Thickness in Semiconductor and Other Wafers

NASA Technical Reports Server (NTRS)

Okojie, Robert S. (Inventor)

2002-01-01

A method and apparatus for processing a wafer comprising a material selected from an electrical semiconducting material and an electrical insulating material is presented. The wafer has opposed generally planar front and rear sides and a peripheral edge, wherein said wafer is pressed against a pad in the presence of a slurry to reduce its thickness. The thickness of the wafer is controlled by first forming a recess such as a dimple on the rear side of the wafer. A first electrical conducting strip extends from a first electrical connection means to the base surface of the recess to the second electrical connector. The first electrical conducting strip overlies the base surface of the recess. There is also a second electrical conductor with an electrical potential source between the first electrical connector and the second electrical connector to form. In combination with the first electrical conducting strip, the second electrical conductor forms a closed electrical circuit, and an electrical current flows through the closed electrical circuit. From the front side of the wafer the initial thickness of the wafer is reduced by lapping until the base surface of the recess is reached. The conductive strip is at least partially removed from the base surface to automatically stop the lapping procedure and thereby achieve the desired thickness.

Embedded Heaters for Joining or Separating Plastic Parts

NASA Technical Reports Server (NTRS)

Bryant, Melvin A., III

2004-01-01

A proposed thermal-bonding technique would make it possible to join or separate thermoplastic parts quickly and efficiently. The technique would eliminate the need for conventional welding or for such conventional fastening components as bolted flanges or interlocking hooks. The technique could be particularly useful in the sign industry (in which large quantities of thermoplastics are used) or could be used to join plastic pipes. A thin sheet of a suitable electrically conductive material would be formed to fit between two thermoplastic parts to be joined (see figure). The electrically conductive sheet and the two parts would be put together tightly, then an electrical current would be sent through the conductor to heat the thermoplastic locally. The magnitude of the current and the heating time would be chosen to generate just enough heat to cause the thermoplastic to adhere to both sides of the electrically conductive sheet. Optionally, the electrically conductive sheet could contain many small holes to provide purchase or to increase electrical resistance to facilitate the generation of heat. After thermal bonding, the electrically conductive sheet remains as an integral part of the structure. If necessary, the electrically conductive sheet can be reheated later to separate the joined thermoplastic parts.

Electrical Conductivity of Ferritin Proteins by Conductive AFM

NASA Technical Reports Server (NTRS)

Xu, Degao; Watt, Gerald D.; Harb, John N.; Davis, Robert C.

2005-01-01

Electrical conductivity measurements were performed on single apoferritin and holoferritin molecules by conductive atomic force microscopy. Conductivity of self-assembled monolayer films of ferritin molecules on gold surfaces was also measured. Holoferritin was 5-25 times more conductive than apoferritin, indicating that for holoferritin most electron-transfer goes through the ferrihydrite core. With 1 V applied, the average electrical currents through single holoferritin and apoferritin molecules were 2.6 PA and 0.19 PA, respectively.

Modeling of electric field distribution in tissues during electroporation

PubMed Central

2013-01-01

Background Electroporation based therapies and treatments (e.g. electrochemotherapy, gene electrotransfer for gene therapy and DNA vaccination, tissue ablation with irreversible electroporation and transdermal drug delivery) require a precise prediction of the therapy or treatment outcome by a personalized treatment planning procedure. Numerical modeling of local electric field distribution within electroporated tissues has become an important tool in treatment planning procedure in both clinical and experimental settings. Recent studies have reported that the uncertainties in electrical properties (i.e. electric conductivity of the treated tissues and the rate of increase in electric conductivity due to electroporation) predefined in numerical models have large effect on electroporation based therapy and treatment effectiveness. The aim of our study was to investigate whether the increase in electric conductivity of tissues needs to be taken into account when modeling tissue response to the electroporation pulses and how it affects the local electric distribution within electroporated tissues. Methods We built 3D numerical models for single tissue (one type of tissue, e.g. liver) and composite tissue (several types of tissues, e.g. subcutaneous tumor). Our computer simulations were performed by using three different modeling approaches that are based on finite element method: inverse analysis, nonlinear parametric and sequential analysis. We compared linear (i.e. tissue conductivity is constant) model and non-linear (i.e. tissue conductivity is electric field dependent) model. By calculating goodness of fit measure we compared the results of our numerical simulations to the results of in vivo measurements. Results The results of our study show that the nonlinear models (i.e. tissue conductivity is electric field dependent: σ(E)) fit experimental data better than linear models (i.e. tissue conductivity is constant). This was found for both single tissue and composite tissue. Our results of electric field distribution modeling in linear model of composite tissue (i.e. in the subcutaneous tumor model that do not take into account the relationship σ(E)) showed that a very high electric field (above irreversible threshold value) was concentrated only in the stratum corneum while the target tumor tissue was not successfully treated. Furthermore, the calculated volume of the target tumor tissue exposed to the electric field above reversible threshold in the subcutaneous model was zero assuming constant conductivities of each tissue. Our results also show that the inverse analysis allows for identification of both baseline tissue conductivity (i.e. conductivity of non-electroporated tissue) and tissue conductivity vs. electric field (σ(E)) of electroporated tissue. Conclusion Our results of modeling of electric field distribution in tissues during electroporation show that the changes in electrical conductivity due to electroporation need to be taken into account when an electroporation based treatment is planned or investigated. We concluded that the model of electric field distribution that takes into account the increase in electric conductivity due to electroporation yields more precise prediction of successfully electroporated target tissue volume. The findings of our study can significantly contribute to the current development of individualized patient-specific electroporation based treatment planning. PMID:23433433

Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges.

PubMed

Manthilake, Geeth; Bolfan-Casanova, Nathalie; Novella, Davide; Mookherjee, Mainak; Andrault, Denis

2016-05-01

Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (~1 S/m) that has often been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed anomalously high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite. In this present study, we have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting. In our experiment, we observe two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity to ~3 × 10(-3) S/m can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity of up to 7 × 10(-1) S/m. This is related to the growth of an interconnected network of a highly conductive and chemically impure magnetite mineral phase. Thus, the dehydration of chlorite and associated processes are likely to be crucial in explaining the anomalously high electrical conductivity observed in mantle wedges. Chlorite dehydration in the mantle wedge provides an additional source of aqueous fluid above the slab and could also be responsible for the fixed depth (120 ± 40 km) of melting at the top of the subducting slab beneath the subduction-related volcanic arc front.

Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges

PubMed Central

Manthilake, Geeth; Bolfan-Casanova, Nathalie; Novella, Davide; Mookherjee, Mainak; Andrault, Denis

2016-01-01

Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (~1 S/m) that has often been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed anomalously high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite. In this present study, we have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting. In our experiment, we observe two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity to ~3 × 10−3 S/m can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity of up to 7 × 10−1 S/m. This is related to the growth of an interconnected network of a highly conductive and chemically impure magnetite mineral phase. Thus, the dehydration of chlorite and associated processes are likely to be crucial in explaining the anomalously high electrical conductivity observed in mantle wedges. Chlorite dehydration in the mantle wedge provides an additional source of aqueous fluid above the slab and could also be responsible for the fixed depth (120 ± 40 km) of melting at the top of the subducting slab beneath the subduction-related volcanic arc front. PMID:27386526

Chemical Detection using Electrically Open Circuits having no Electrical Connections

NASA Technical Reports Server (NTRS)

Woodward, Stanley E.; Olgesby, Donald M.; Taylor, Bryant D.; Shams, Qamar A.

2008-01-01

This paper presents investigations to date on chemical detection using a recently developed method for designing, powering and interrogating sensors as electrically open circuits having no electrical connections. In lieu of having each sensor from a closed circuit with multiple electrically connected components, an electrically conductive geometric pattern that is powered using oscillating magnetic fields and capable of storing an electric field and a magnetic field without the need of a closed circuit or electrical connections is used. When electrically active, the patterns respond with their own magnetic field whose frequency, amplitude and bandwidth can be correlated with the magnitude of the physical quantities being measured. Preliminary experimental results of using two different detection approaches will be presented. In one method, a thin film of a reactant is deposited on the surface of the open-circuit sensor. Exposure to a specific targeted reactant shifts the resonant frequency of the sensor. In the second method, a coating of conductive material is placed on a thin non-conductive plastic sheet that is placed over the surface of the sensor. There is no physical contact between the sensor and the electrically conductive material. When the conductive material is exposed to a targeted reactant, a chemical reaction occurs that renders the material non-conductive. The change in the material s electrical resistance within the magnetic field of the sensor alters the sensor s response bandwidth and amplitude, allowing detection of the reaction without having the reactants in physical contact with the sensor.

External electric field driven modification of the anomalous and spin Hall conductivities in Fe thin films on MgO(001)

NASA Astrophysics Data System (ADS)

Pradipto, Abdul-Muizz; Akiyama, Toru; Ito, Tomonori; Nakamura, Kohji

2018-01-01

The effects of applying external electric fields to the anomalous and spin Hall conductivities in Fe thin-film models with different layer thicknesses on MgO(001) are investigated by using first-principles calculations. We observe that, for the considered systems, the application of positive electric field associated with the accumulation of negative charges on the Fe side generally decreases (increases) the anomalous (spin) Hall conductivities. The mapping of the Hall conductivities within the two-dimensional Brillouin zone shows that the electric-field-induced modifications are related to the modification of the band structures of the atoms at the interface with the MgO substrate. In particular, the external electric field affects the Hall conductivities via the modifications of the dx z,dy z orbitals, in which the application of positive electric field pushes the minority-spin states of the dx z,dy z bands closer to the Fermi level. Better agreement with the anomalous Hall conductivity for bulk Fe and a more realistic scenario for the electric field modification of Hall conductivities are obtained by using the thicker layers of Fe on MgO (Fe3/MgO and Fe5/MgO).

Non-permeable substrate carrier for electroplating

DOEpatents

Abas, Emmanuel Chua; Chen, Chen-An; Ma, Diana Xiaobing; Ganti, Kalyana Bhargava

2012-11-27

One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier comprises a non-conductive carrier body on which the substrates are to be held. Electrically-conductive lines are embedded within the carrier body, and a plurality of contact clips are coupled to the electrically-conductive lines embedded within the carrier body. The contact clips hold the substrates in place and electrically couple the substrates to the electrically-conductive lines. The non-conductive carrier body is continuous so as to be impermeable to flow of electroplating solution through the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

Non-permeable substrate carrier for electroplating

DOEpatents

Abas, Emmanuel Chua; Chen, Chen-an; Ma, Diana Xiaobing; Ganti, Kalyana; Divino, Edmundo Anida; Ermita, Jake Randal G.; Capulong, Jose Francisco S.; Castillo, Arnold Villamor

2015-12-29

One embodiment relates to a substrate carrier for use in electroplating a plurality of substrates. The substrate carrier comprises a non-conductive carrier body on which the substrates are to be held. Electrically-conductive lines are embedded within the carrier body, and a plurality of contact clips are coupled to the electrically-conductive lines embedded within the carrier body. The contact clips hold the substrates in place and electrically couple the substrates to the electrically-conductive lines. The non-conductive carrier body is continuous so as to be impermeable to flow of electroplating solution through the non-conductive carrier body. Other embodiments, aspects and features are also disclosed.

Development costs for a nuclear electric propulsion stage.

NASA Technical Reports Server (NTRS)

Mondt, J. F.; Prickett, W. Z.

1973-01-01

Development costs are presented for an unmanned nuclear electric propulsion (NEP) stage based upon a liquid metal cooled, in-core thermionic reactor. A total of 120 kWe are delivered to the thrust subsystem which employs mercury ion engines for electric propulsion. This study represents the most recent cost evaluation of the development of a reactor power system for a wide range of nuclear space power applications. These include geocentric, and outer planet and other deep space missions. The development program is described for the total NEP stage, based upon specific development programs for key NEP stage components and subsystems.

Strategic Technologies for Deep Space Transport

NASA Technical Reports Server (NTRS)

Litchford, Ronald J.

2016-01-01

Deep space transportation capability for science and exploration is fundamentally limited by available propulsion technologies. Traditional chemical systems are performance plateaued and require enormous Initial Mass in Low Earth Orbit (IMLEO) whereas solar electric propulsion systems are power limited and unable to execute rapid transits. Nuclear based propulsion and alternative energetic methods, on the other hand, represent potential avenues, perhaps the only viable avenues, to high specific power space transport evincing reduced trip time, reduced IMLEO, and expanded deep space reach. Here, key deep space transport mission capability objectives are reviewed in relation to STMD technology portfolio needs, and the advanced propulsion technology solution landscape is examined including open questions, technical challenges, and developmental prospects. Options for potential future investment across the full compliment of STMD programs are presented based on an informed awareness of complimentary activities in industry, academia, OGAs, and NASA mission directorates.

Design and application of electromechanical actuators for deep space missions

NASA Technical Reports Server (NTRS)

Haskew, Tim A.; Wander, John

1995-01-01

This third semi-annual progress report covers the reporting period from August 16, 1994 through February 15, 1995 on NASA Grant NAG8-240, 'Design and Application of Electromechanical Actuators for Deep Space Missions'. There are two major report sections: Motor Control Status/Electrical Experiment Planning and Experiment Planning and Initial Results. The primary emphasis of our efforts during the reporting period has been final construction and testing of the laboratory facilities. As a result, this report is dedicated to that topic.

An update on the Deep Space 1 power system: SCARLET integration and test results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, D.M.; Murphy, D.M.

1998-07-01

The Solar Concentrator Arrays with Refractive Linear Element Technology (SCARLET) system for the Deep Space 1 (DS1) spacecraft have been completed and delivered to JPL for integration with the spacecraft. This paper describes the array assembly, the qualification test program, and the results of the qualification tests. The array will provide power to the DS1 spacecraft and its NSTAR ion electric propulsion system. Launch is scheduled for October, 1998 from Kennedy Space Center, FL.

Finite difference time domain (FDTD) modeling of implanted deep brain stimulation electrodes and brain tissue.

PubMed

Gabran, S R I; Saad, J H; Salama, M M A; Mansour, R R

2009-01-01

This paper demonstrates the electromagnetic modeling and simulation of an implanted Medtronic deep brain stimulation (DBS) electrode using finite difference time domain (FDTD). The model is developed using Empire XCcel and represents the electrode surrounded with brain tissue assuming homogenous and isotropic medium. The model is created to study the parameters influencing the electric field distribution within the tissue in order to provide reference and benchmarking data for DBS and intra-cortical electrode development.

150 kW Class Solar Electric Propulsion Spacecraft Power Architecture Model

NASA Technical Reports Server (NTRS)

Csank, Jeffrey T.; Aulisio, Michael V.; Loop, Benjamin

2017-01-01

The National Aeronautics and Space Administration (NASA) Solar Electric Propulsion Technology Demonstration Mission (SEP TDM), in conjunction with PC Krause and Associates, has created a Simulink-based power architecture model for a 50 kilo-Watt (kW) solar electric propulsion system. NASA has extended this model to investigate 150 kW solar electric propulsion systems. Increasing the power capability to 150 kW is an intermediate step to the anticipated power requirements for Mars and other deep space applications. The high-power solar electric propulsion capability has been identified as a critical part of NASA’s future beyond-low-Earth-orbit for human-crewed exploration missions. This paper presents four versions of a 150 kW architecture, simulation results, and a discussion of their merits.

Conductive polymer layers to limit transfer of fuel reactants to catalysts of fuel cells to reduce reactant crossover

DOEpatents

Stanis, Ronald J.; Lambert, Timothy N.

2016-12-06

An apparatus of an aspect includes a fuel cell catalyst layer. The fuel cell catalyst layer is operable to catalyze a reaction involving a fuel reactant. A fuel cell gas diffusion layer is coupled with the fuel cell catalyst layer. The fuel cell gas diffusion layer includes a porous electrically conductive material. The porous electrically conductive material is operable to allow the fuel reactant to transfer through the fuel cell gas diffusion layer to reach the fuel cell catalyst layer. The porous electrically conductive material is also operable to conduct electrons associated with the reaction through the fuel cell gas diffusion layer. An electrically conductive polymer material is coupled with the fuel cell gas diffusion layer. The electrically conductive polymer material is operable to limit transfer of the fuel reactant to the fuel cell catalyst layer.

Method of forming electrical pathways in indium-tin-oxide coatings

DOEpatents

Haynes, T.E.

1996-12-03

An electrical device includes a substrate having an ITO coating thereon, a portion of which is conductive and defines at least one electrical pathway, and the balance of the ITO being insulative. The device is made by the following general steps: a. providing a substrate having a conductive ITO coating on at least one surface thereof; b. rendering a preselected portion of the coating of conductive ITO insulative, leaving the remaining portion of conductive ITO as at least one electrical pathway. 8 figs.