Air velocity distributions inside tree canopies from a variable-rate air-assisted sprayer

USDA-ARS?s Scientific Manuscript database

A variable-rate, air assisted, five-port sprayer had been in development to achieve variable discharge rates of both liquid and air. To verify the variable air rate capability by changing the fan inlet diameter of the sprayer, air jet velocities impeded by plant canopies were measured at various loc...

Test results of a ten cell bipolar nickel-hydrogen battery

NASA Technical Reports Server (NTRS)

Cataldo, R. L.

1983-01-01

A ten cell bipolar nickel hydrogen 6.5 ampere-hour battery demonstrated over 2000 low Earth orbit cycles at an 80 percent depth-of-discharge. Charge/discharge cyclic ampere-hour and watt-hour efficiencies of 88 and 76 percent, respectively, observed. Peak power capability was determined at 1.1 kW. A 10C discharge rate yields 83 percent of the nominal stark capacity to the 1.0 volt cut off in just under 6 minutes.

Quantitative characterization of arc discharge as vacuum interface

DOE PAGES

Huang, S.; Zhu, K.; Lu, Y. R.; ...

2014-12-19

An arc discharge with channel diameters of 3 mm and 6 mm and lengths between 30mm and 60mm was experimentally investigated for its potential to function as plasma window, i.e., interface vacuum regions of different pressures. In this study, electron temperature of the plasma channel measured spectroscopically varied in the range of 7000K to 15000K, increasing with discharge current while decreasing with gas flow rate. The plasma window had a slightly positive I-V characteristics over the whole range of investigated current 30A–70 A. Measurements of pressure separation capability, which were determined by input current, gas flow rate, discharge channel diameter,more » and length, were well explained by viscosity effect and “thermal-block” effect. The experimental results of global parameters including temperature, gas flow rate, and voltage had a good agreement with the simulation results calculated by an axis-symmetry Fluent-based magneto-hydrodynamic model.« less

Test results of a ten cell bipolar nickel-hydrogen battery

NASA Technical Reports Server (NTRS)

Cataldo, R. L.

1983-01-01

A ten cell bipolar nickel hydrogen 6.5 ampere-hour battery demonstrated over 2000 low earth orbit cycles at an 80 percent depth-of-discharge. Charge/discharge cyclic ampere-hour and watt-hour efficiencies of 88 and 76 percent, respectively, observed. Peak power capability was determined at 1.1 kW. A 10C discharge rate yields 83 percent of the nominal stark capacity to the 1.0 volt cut off in just under 6 minutes. Previously announced in STAR as N83-26253

High voltage pulse ignition of mercury discharge hollow cathodes

NASA Technical Reports Server (NTRS)

Wintucky, E. G.

1973-01-01

A high voltage pulse generated by a capacitor discharge into a step-up transformer has been demonstrated capable of consistently igniting hollow cathode mercury discharges at propellant flows and heater power levels much below those required by conventional cathode starting. Results are presented for 3.2-mm diameter enclosed and open keeper cathodes. Starting characteristics are shown to depend on keeper voltage, mercury flow rate, heater power, keeper orifice size, emissive materials, and electrode to which the pulse is applied. This starting technique has been used to start a cathode over 10,000 times without any degradation of starting capability. The starting reliability, propellant and power savings offered by the high voltage pulse start should favorably impact performance of electron bombardment thrusters in missions requiring many on-off duty cycles.

Impact of different environmental conditions on lithium-ion batteries performance through the thermal monitoring with fiber sensors

NASA Astrophysics Data System (ADS)

Nascimento, Micael; Ferreira, Marta S.; Pinto, João. L.

2017-08-01

In this work, an optical fiber sensing network has been developed to assess the impact of different environmental conditions on lithium batteries performance through the real time thermal monitoring. The battery is submitted to constant current charge and different discharge C-rates, under normal and abusive operating conditions. The results show that for the discharge C-rate of 5.77C, the LiB under cold and dry climates had 32.5% and 27.2% lower temperature variations, when compared with temperate climates, respectively. The higher temperature shift detected in the temperate climate was related to the battery better performance regarding discharge capacity and power capabilities.

Development of ambient temperature secondary lithium cells

NASA Technical Reports Server (NTRS)

Subbarao, S.; Shen, D. H.; Dawson, S.; Deligiannis, F.; Taraszkiewicz, J.; Halpert, G.

1988-01-01

JPL is developing ambient temperature secondary lithium cells for future spacecraft applications. Prior studies on experimental laboratory type Li-TiS2 cells yielded promising results in terms of cycle life and rate capability. To further assess the performance of this cell, 5 Ah engineering model cells were developed. Initially baseline cells were designed and fabricated. Each cell had 15 cathodes and 16 anodes and the ratio of anode to cathode capacity is 6:1. A solution of 1.5 molar LiAsF6 in 2Me-THF was used as the electrolyte. Cells were evaluated for their cycle life at C/1 and C/5 discharge rates and 100 percent depth of discharge. The cells were cycled between voltage limits 1.7 and 2.8 volts. The rate of charge in all cases is C/10. The results obtained indicate that cells can operate at C/10 to C/2 discharge rates and have an initial energy density of 70 Wh/kg. Cells delivered more than 100 cycles at C/2 discharge rate. The details of cell design, the test program, and the results obtained are described.

Development of ambient temperature secondary lithium cells

NASA Technical Reports Server (NTRS)

Subbarao, S.; Shen, D. H.; Dawson, S.; Deligiannis, F.; Taraszkiewicz, J.; Halpert, Gerald

1987-01-01

JPL is developing ambient temperature secondary lithium cells for future spacecraft applications. Prior studies on experimental laboratory type Li-TiS2 cells yielded promising results in terms of cycle life and rate capability. To further assess the performance of this cell, 5 Ah engineering model cells were developed. Initially baseline cells were designed and fabricated. Each cell had 15 cathodes and 16 anodes and the ratio of anode to cathode capacity is 6:1. A solution of 1.5 molar LiAsF6 in 2Me-THF was used as the electrolyte. Cells were evaluated for their cycle life at C/1 and C/5 discharge rates and 100 percent depth of discharge. The cells were cycled between voltage limits 1.7 and 2.8 volts. The rate of charge in all cases is C/10. The results obtained indicate that cells can operate at C/10 to C/2 discharge rates and have an initial energy density of 70 Wh/kg. Cells delivered more than 100 cycles at C/2 discharge rate. The details of cell design, the test program, and the results obtained are described.

Measurements of heat generation in prismatic Li-ion batteries

NASA Astrophysics Data System (ADS)

Chen, Kaiwei; Unsworth, Grant; Li, Xianguo

2014-09-01

An accurate understanding of the characteristics of battery heat generation is essential to the development and success of thermal management systems for electric vehicles. In this study, a calorimeter capable of measuring the heat generation rates of a prismatic battery is developed and verified by using a controllable electric heater. The heat generation rates of a prismatic A123 LiFePO4 battery is measured for discharge rates ranging from 0.25C to 3C and operating temperature ranging from -10 °C to 40 °C. At low rates of discharge the heat generation is not significant, even becoming endothermic at the battery operating temperatures of 30 °C and 40 °C. Heat of mixing is observed to be a non-negligible component of total heat generation at discharge rates as low as 0.25C for all tested battery operating temperatures. A double plateau in battery discharge curve is observed for operating temperatures of 30 °C and 40 °C. The developed experimental facility can be used for the characterization of heat generation for any prismatic battery, regardless of chemistries.

Studies on niobium triselenide cathode material for lithium rechargeable cells

NASA Technical Reports Server (NTRS)

Ratnakumar, B. V.; Ni, C. L.; Distefano, S.; Somoano, R. B.; Bankston, C. P.

1988-01-01

NbSe3 exhibits superior characteristics such as high capacity, high volumetric and gravimetric energy densities, and high discharge rate capability, as compared to other intercalating cathodes. This paper reports the preparation, characterization, and performance of NbSe3. Several electrochemical techniques, such as cyclic voltammetry, constant-current/constant-potential discharges, dc potentiodynamic scans, ac impedance, and ac voltammetry, have been used to give insight to the mechanisms of intercalation of three lithiums with NbSe3 and also into the rate determining process in the reduction of NbSe3.

A facile and scalable method to prepare carbon nanotube-grafted-graphene for high performance Li-S battery

NASA Astrophysics Data System (ADS)

Wang, Q. Q.; Huang, J. B.; Li, G. R.; Lin, Z.; Liu, B. H.; Li, Z. P.

2017-01-01

A carbon nanotube-grafted-graphene (CNT-g-Gr) is developed for enhancements of electrical conduction and polysulfide (PS) absorption to improve rate performance and cycleability of lithium-sulfur battery. The CNT-g-Gr is prepared through CNT growth on Ni-deposited graphene sheet which is fabricated via pyrolysis of glucose in a molten salt. The obtained CNT-g-Gr shows much higher specific surface area and PS adsorption capability than graphene. The in-situ formed Ni nanoparticles on graphene sheet not only serve as the catalytic sites for CNT growth, but also function as the anchor-sites for polar PS absorption. The CNT-g-Gr contributes a superb PS adsorption capability arising from graphene and CNT absorbing weakly-polar PS species, and Ni nanoparticles absorbing the species with stronger polarity. The resultant Li-S battery with the CNT-g-Gr shows excellent cycleability and rate performance. A stable discharge capacity of 900 mAh g-1 (with low capacity degradation rate) and a rate capacity of 260 mAh g-1 at 30 C discharge rate have been achieved.

Evaluating the combined effects of source zone mass release rates and aquifer heterogeneity on solute discharge uncertainty

NASA Astrophysics Data System (ADS)

de Barros, Felipe P. J.

2018-07-01

Quantifying the uncertainty in solute mass discharge at an environmentally sensitive location is key to assess the risks due to groundwater contamination. Solute mass fluxes are strongly affected by the spatial variability of hydrogeological properties as well as release conditions at the source zone. This paper provides a methodological framework to investigate the interaction between the ubiquitous heterogeneity of the hydraulic conductivity and the mass release rate at the source zone on the uncertainty of mass discharge. Through the use of perturbation theory, we derive analytical and semi-analytical expressions for the statistics of the solute mass discharge at a control plane in a three-dimensional aquifer while accounting for the solute mass release rates at the source. The derived solutions are limited to aquifers displaying low-to-mild heterogeneity. Results illustrate the significance of the source zone mass release rate in controlling the mass discharge uncertainty. The relative importance of the mass release rate on the mean solute discharge depends on the distance between the source and the control plane. On the other hand, we find that the solute release rate at the source zone has a strong impact on the variance of the mass discharge. Within a risk context, we also compute the peak mean discharge as a function of the parameters governing the spatial heterogeneity of the hydraulic conductivity field and mass release rates at the source zone. The proposed physically-based framework is application-oriented, computationally efficient and capable of propagating uncertainty from different parameters onto risk metrics. Furthermore, it can be used for preliminary screening purposes to guide site managers to perform system-level sensitivity analysis and better allocate resources.

Test Results of a Ten Cell Bipolar Nickel-hydrogen Battery

NASA Technical Reports Server (NTRS)

Cataldo, R. L.

1984-01-01

A study was initiated to design and evaluate a new design concept for nickel-hydrogen cells. This concept involved constructing a battery in a bipolar stack with cells consisting of a one plate for each nickel and hydrogen electrode. Preliminary designs at the system level of this concept promised improvements in both volumetric and gravimetric energy densities, thermal management, life extension, costs, and peak power capability over more conventional designs. Test results were most encouraging. This preprototype battery, built with less than ideal components and hardware, exceeded expectations. A total of 2000 LEO cycles at 80 percent depth of discharge were accrued. A cycle life goal of 30,000 cycles appears achievable with minor design changes. These improvements include advanced technology nickel electrodes, insulated bipolar plates and specifically designed frames to minimize shunt currents. The discharge rate capability of this design exceeds 25C. At the 10C discharge rate, 80% of the battery capacity can be withdrawn in six minutes. This data shows that the bipolar design is well suited for those applications requiring high peak power pulses.

Combined corona discharge and UV photoionization source for ion mobility spectrometry.

PubMed

Bahrami, Hamed; Tabrizchi, Mahmoud

2012-08-15

An ion mobility spectrometer is described which is equipped with two non-radioactive ion sources, namely an atmospheric pressure photoionization and a corona discharge ionization source. The two sources cannot only run individually but are additionally capable of operating simultaneously. For photoionization, a UV lamp was mounted parallel to the axis of the ion mobility cell. The corona discharge electrode was mounted perpendicular to the UV radiation. The total ion current from the photoionization source was verified as a function of lamp current, sample flow rate, and drift field. Simultaneous operation of the two ionization sources was investigated by recording ion mobility spectra of selected samples. The design allows one to observe peaks from either the corona discharge or photoionization individually or simultaneously. This makes it possible to accurately compare peaks in the ion mobility spectra from each individual source. Finally, the instrument's capability for discriminating two peaks appearing in approximately identical drift times using each individual ionization source is demonstrated. Copyright © 2012 Elsevier B.V. All rights reserved.

In situ engineering of the electrode-electrolyte interface for stabilized overlithiated cathodes

DOE PAGES

Evans, Tyler; Piper, Daniela Molina; Sun, Huaxing; ...

2017-01-05

Here, the first-ever demonstration of stabilized Si/lithium-manganese-rich full cells, capable of retaining >90% energy over early cycling and >90% capacity over more than 750 cycles at the 1C rate (100% depth-of-discharge), is made through the utilization of a modified ionic liquid electrolyte capable of forming a favorable cathode-electrolyte interface.

Surface Modified Pinecone Shaped Hierarchical Structure Fluorinated Mesocarbon Microbeads for Ultrafast Discharge and Improved Electrochemical Performances

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

Dai, Yang; Fang, Yuan; Cai, Sendan

2016-12-01

Among all primary lithium batteries, Li/CF x primary battery possesses the highest energy density of 2180 Wh kg -1. However, a key limitation is its poor rate capability because the cathode material CF x is intrinsically a poor electronic conductor. Here, we developed a so-called “doing subtraction” method to modify the pinecone shaped fluorinated mesocarbon microbead (F-MCMB). The modified fluorinated mesocarbon microbead (MF-MCMB), manifests the advantage of open-framed structure, possesses good electronic conductivity and removes transport barrier for lithium ions. Thus, high capacity performance and excellent rate capability without compromising capacity can be obtained. A capacity of 343 mAhg -1more » and a maximum power density of 54600 W kg -1 are realized at an ultrafast rate of 40 C (28A g -1). Additionally, the MF-MCMB cathode does not show any voltage delay even at 5C during the discharge, which is a remarkable improvement over the state-of-the-art CF xmaterials.« less

Arc Discharges of a Pure Carbon Strip Affected by Dynamic Contact Force during Current-Carrying Sliding

PubMed Central

Zhang, Yanyan; Zhang, Yongzhen

2018-01-01

Arc discharges of a pure carbon strip induced by dynamic contact force were studied on a pin-on-disk tribometer. It was found that arc discharges were produced periodically in accordance with the period of the dynamic contact force. The arcing rate of the pure carbon strip increased with an increase of frequency f and amplitude B, which led to a decrease of current-carrying quality. These influences at high velocities became much more significant. A critical point of the arcing rate at around 2% was detected. Lower than 2%, the pure carbon strip was able to maintain its excellent current-carrying capability; higher than this point, the current-carrying quality deteriorated abruptly. SEM and XPS analysis show that the element Cu detected on the worn surface at lower arcing rates was metal Cu. CuO was found at higher arcing rates. This indicated that the wear mechanism transferred from mechanical wear to arc erosion with the increase of the arcing rate. PMID:29762496

Direct view on the phase evolution in individual LiFePO4 nanoparticles during Li-ion battery cycling.

PubMed

Zhang, Xiaoyu; van Hulzen, Martijn; Singh, Deepak P; Brownrigg, Alex; Wright, Jonathan P; van Dijk, Niels H; Wagemaker, Marnix

2015-09-23

Phase transitions in Li-ion electrode materials during (dis)charge are decisive for battery performance, limiting high-rate capabilities and playing a crucial role in the cycle life of Li-ion batteries. However, the difficulty to probe the phase nucleation and growth in individual grains is hindering fundamental understanding and progress. Here we use synchrotron microbeam diffraction to disclose the cycling rate-dependent phase transition mechanism within individual particles of LiFePO4, a key Li-ion electrode material. At low (dis)charge rates well-defined nanometer thin plate-shaped domains co-exist and transform much slower and concurrent as compared with the commonly assumed mosaic transformation mechanism. As the (dis)charge rate increases phase boundaries become diffuse speeding up the transformation rates of individual grains. Direct observation of the transformation of individual grains reveals that local current densities significantly differ from what has previously been assumed, giving new insights in the working of Li-ion battery electrodes and their potential improvements.

Direct view on the phase evolution in individual LiFePO4 nanoparticles during Li-ion battery cycling

PubMed Central

Zhang, Xiaoyu; van Hulzen, Martijn; Singh, Deepak P.; Brownrigg, Alex; Wright, Jonathan P.; van Dijk, Niels H.; Wagemaker, Marnix

2015-01-01

Phase transitions in Li-ion electrode materials during (dis)charge are decisive for battery performance, limiting high-rate capabilities and playing a crucial role in the cycle life of Li-ion batteries. However, the difficulty to probe the phase nucleation and growth in individual grains is hindering fundamental understanding and progress. Here we use synchrotron microbeam diffraction to disclose the cycling rate-dependent phase transition mechanism within individual particles of LiFePO4, a key Li-ion electrode material. At low (dis)charge rates well-defined nanometer thin plate-shaped domains co-exist and transform much slower and concurrent as compared with the commonly assumed mosaic transformation mechanism. As the (dis)charge rate increases phase boundaries become diffuse speeding up the transformation rates of individual grains. Direct observation of the transformation of individual grains reveals that local current densities significantly differ from what has previously been assumed, giving new insights in the working of Li-ion battery electrodes and their potential improvements. PMID:26395323

Arc Discharges of a Pure Carbon Strip Affected by Dynamic Contact Force during Current-Carrying Sliding.

PubMed

Zhang, Yanyan; Zhang, Yongzhen; Song, Chenfei

2018-05-15

Arc discharges of a pure carbon strip induced by dynamic contact force were studied on a pin-on-disk tribometer. It was found that arc discharges were produced periodically in accordance with the period of the dynamic contact force. The arcing rate of the pure carbon strip increased with an increase of frequency f and amplitude B , which led to a decrease of current-carrying quality. These influences at high velocities became much more significant. A critical point of the arcing rate at around 2% was detected. Lower than 2%, the pure carbon strip was able to maintain its excellent current-carrying capability; higher than this point, the current-carrying quality deteriorated abruptly. SEM and XPS analysis show that the element Cu detected on the worn surface at lower arcing rates was metal Cu. CuO was found at higher arcing rates. This indicated that the wear mechanism transferred from mechanical wear to arc erosion with the increase of the arcing rate.

Apparatus and method for tuned unsteady flow purging of high pulse rate spark gaps

DOEpatents

Thayer, III, William J.

1990-01-01

A spark gap switch apparatus is disclosed which is capable of operating at a high pulse rate which comprises an insulated housing; a pair of spaced apart electrodes each having one end thereof within a first bore formed in the housing and defining a spark gap therebetween; a pressure wave reflector in the first bore in the housing and spaced from the spark gap and capable of admitting purge flow; and a second enlarged bore contiguous with the first bore and spaced from the opposite side of the spark gap; whereby pressure waves generated during discharge of a spark across the spark gap will reflect off the wave reflector and back from the enlarged bore to the spark gap to clear from the spark gap hot gases residues generated during the discharge and simultaneously restore the gas density and pressure in the spark gap to its initial value.

High specific energy, high capacity nickel-hydrogen cell design

NASA Technical Reports Server (NTRS)

Wheeler, James R.

1993-01-01

A 3.5 inch rabbit-ear-terminal nickel-hydrogen cell has been designed and tested to deliver high capacity at a C/1.5 discharge rate. Its specific energy yield of 60.6 wh/kg is believed to be the highest yet achieved in a slurry-process nickel-hydrogen cell, and its 10 C capacity of 113.9 AH the highest capacity yet made at a discharge rate this high in the 3.5 inch diameter size. The cell also demonstrated a pulse capability of 180 amps for 20 seconds. Specific cell parameters, performance, and future test plans are described.

Non-contact flow gauging for the extension and development of rating curves

NASA Astrophysics Data System (ADS)

Perks, Matthew; Large, Andy; Russell, Andy

2015-04-01

Accurate measurement of river discharge is fundamental to understanding hydrological processes, associated hazards and ecological responses within fluvial systems. Established protocols for determining river discharge are partial, predominantly invasive and logistically difficult during high flows. There is demand for new methods for accurate quantification of flow velocity under high-flow/flood conditions to in turn enable better post-event reconstruction of peak discharge. As a consequence considerable effort has been devoted to the development of innovative technologies for the representation of flow in open channels. Remotely operated fixed and mobile systems capable of providing quantitative estimates of instantaneous and time-averaged flow characteristics using non-contact methods has been a major development. Amongst the new approaches for stand-alone continuous monitoring of surface flows is Large Scale Particle Image Velocimetry (LSPIV). Here we adapt the LSPIV concept, to provide continuous discharge measurements in non-uniform channels with complex flow conditions. High Definition videos (1080p; 30fps) of the water surface are acquired at 5 minute intervals. The image is rectified to correct for perspective distortion using a new, open source tool which minimises errors resulting from oblique image capture. Naturally occurring artefacts on the water surface (e.g. bubbles, debris, etc.) are tracked with the Kanade-Lucas-Tomasi (KLT) algorithm. The data generated is in the form of a complex surface water velocity field which can be interrogated to extract a range of hydrological information such as the streamwise velocity at a cross-section of interest, or even allow the interrogation of hydrodynamic flow structures. Here we demonstrate that this approach is capable of generating river discharge data comparable to concurrent measurements made using existing, accepted technologies (e.g. ADCP). The outcome is better constraint and extension of rating curves. The approach is suited to water management authorities throughout Europe who seek ever-increasingly cost-effective and non-invasive techniques for maximising the monitoring capabilities of their operational network.

Advanced nickel-metal hydride cell development. Final report, September 1993--March 1996

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

Lim, Hong S.

1996-03-01

Inert gas atomization using metal hydride alloys for a Ni/MH{sub x}cell was studied. Atomization of the alloys was demonstrated on a small production scale up to batch size of several kg. Relative performance of the atomized and nonatomized alloys was investigated for the electrode material in a Ni/MH{sub x} cell. The study included effects of charge-discharge rates, temperature, and particle size on cell voltage (polarization) and specific capacity. Results show that the specific capacity of the present atomized alloys was apprecialy smaller than that of the nonatomized powder, especially for initial cycles. Full activation of the atomized alloys oftentook severalmore » hundreds of cycles. However, no appreciable difference in discharge rate capability was observed with R10 and R12 alloys. Chemical compositions were indistinguishable, although the oxygen contents of the atomized alloys were always higher. Effects of Ni and Cu coating on alloy performance were studied after electroless coating; the coatings noticeably improved the electrode rate capability for all the alloys. The electrode polarization was esecially improved, but not the cycle life. Further studies are needed.« less

Preparation of Layered-Spinel Microsphere/Reduced Graphene Oxide Cathode Materials for Ultrafast Charge-Discharge Lithium-Ion Batteries.

PubMed

Luo, Dong; Fang, Shaohua; Yang, Li; Hirano, Shin-Ichi

2017-12-22

Although Li-rich layered oxides (LLOs) have the highest capacity of any cathodes used, the rate capability of LLOs falls short of meeting the requirements of electric vehicles and smart grids. Herein, a layered-spinel microsphere/reduced graphene oxide heterostructured cathode (LS@rGO) is prepared in situ. This cathode is composed of a spinel phase, two layered structures, and a small amount of reduced graphene oxide (1.08 wt % of carbon). The assembly delivers a considerable charge capacity (145 mA h g -1 ) at an ultrahigh charge- discharge rate of 60 C (12 A g -1 ). The rate capability of LS@rGO is influenced by the introduced spinel phase and rGO. X-ray absorption and X-ray photoelectron spectroscopy data indicate that Cr ions move from octahedral lattice sites to tetrahedral lattice sites, and that Mn ions do not participate in the oxidation reaction during the initial charge process. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Culvert analysis program for indirect measurement of discharge

USGS Publications Warehouse

Fulford, Janice M.; ,

1993-01-01

A program based on the U.S. Geological Survey (USGS) methods for indirectly computing peak discharges through culverts allows users to employ input data formats used by the water surface profile program (WSPRO). The program can be used to compute discharge rating surfaces or curves that describe the behavior of flow through a particular culvert or to compute discharges from measurements of upstream of the gradually varied flow equations and has been adapted slightly to provide solutions that minimize the need for the user to determine between different flow regimes. The program source is written in Fortran 77 and has been run on mini-computers and personal computers. The program does not use or require graphics capability, a color monitor, or a mouse.

Cycle life performance of rechargeable lithium ion batteries and mathematical modeling

NASA Astrophysics Data System (ADS)

Ning, Gang

Capacity fade of commercial Sony US 18650 Li-ion batteries cycled at high discharge rates was studied at ambient temperature. Battery cycled at the highest discharge rate (3 C) shows the largest internal resistance increase of 27.7% relative to the resistance of fresh battery. It's been observed anode carbon loses 10.6% of its capability to intercalate or deintercalate Li+ after it was subjected to 300 cycles at discharge rate of 3 C. This loss dominates capacity fade of full battery. A mechanism considering continuous parasitic reaction at anode/electrolyte interface and film thickening has been proposed. First principles based charge-discharge models to simulate cycle life behavior of rechargeable Li-ion batteries have been developed. In the generalized model, transport in both electrolyte phase and solid phase were simultaneously taken into account. Under mild charge-discharge condition, transport of lithium in the electrolyte phase has been neglected in the simplified model. Both models are based on loss of the active lithium ions due to the electrochemical parasitic reaction at anode/electrolyte interface and on rise of the anode film resistance. The effect of parameters such as depth of discharge (DOD), end of charge voltage (EOCV) and overvoltage of the parasitic reaction on the cycle life behavior of a battery has been analyzed. The experimental results obtained at a charge rate of 1 C, discharge rate of 0.5 C, EOCV of 4.0 V and DOD of 0.4 have been used to validate cycle life models. Good agreement between the simulations and the experiments has been achieved up to 1968 cycles with both models. Simulation of cycle life of battery under multiple cycling regimes has also been demonstrated.

Mn-Based Cathode with Synergetic Layered-Tunnel Hybrid Structures and Their Enhanced Electrochemical Performance in Sodium Ion Batteries.

PubMed

Wu, Zhen-Guo; Li, Jun-Tao; Zhong, Yan-Jun; Guo, Xiao-Dong; Huang, Ling; Zhong, Ben-He; Agyeman, Daniel-Adjei; Lim, Jin-Myoung; Kim, Du-Ho; Cho, Maeng-Hyo; Kang, Yong-Mook

2017-06-28

A synergistic approach for advanced cathode materials is proposed. Sodium manganese oxide with a layered-tunnel hybrid structure was designed, synthesized, and subsequently investigated. The layered-tunnel hybrid structure provides fast Na ion diffusivity and high structural stability thanks to the tunnel phase, enabling high rate capability and greatly improved cycling stability compared to that of the pure P2 layered phase while retaining the high specific capacity of the P2 layered phase. The hybrid structure provided a decent discharge capacity of 133.4 mAh g -1 even at 8 C, which exceeds the reported best rate capability for Mn-based cathodes. It also displayed an impressive cycling stability, maintaining 83.3 mAh g -1 after 700 cycles at 10 C. Theoretical calculation and the potentiostatic intermittent titration technique (PITT) demonstrated that this hybrid structure helps enhance Na ion diffusivity during charge and discharge, attaining, as a result, an unprecendented electrochemical performance.

In-Situ Measurement of Hall Thruster Erosion Using a Fiber Optic Regression Probe

NASA Technical Reports Server (NTRS)

Polzink, Kurt A.; Korman, Valentin

2008-01-01

One potential life-limiting mechanism in a Hall thruster is the erosion of the ceramic material comprising the discharge channel. This is especially true for missions that require long thrusting periods and can be problematic for lifetime qualification, especially when attempting to qualify a thruster by analysis rather than a test lasting the full duration of the mission. In addition to lifetime, several analytical and numerical models include electrode erosion as a mechanism contributing to enhanced transport properties. However, there is still a great deal of dispute over the importance of erosion to transport in Hall thrusters. The capability to perform an in-situ measurement of discharge channel erosion is useful in addressing both the lifetime and transport concerns. An in-situ measurement would allow for real-time data regarding the erosion rates at different operating points, providing a quick method for empirically anchoring any analysis geared towards lifetime qualification. Erosion rate data over a thruster's operating envelope would also be useful in the modeling of the detailed physics inside the discharge chamber. A recent fundamental sensor development effort has led to a novel regression, erosion, and ablation sensor technology (REAST). The REAST sensor allows for measurement of real-time surface erosion rates at a discrete surface location. The sensor was tested using a linear Hall thruster geometry, which served as a means of producing plasma erosion of a ceramic discharge chamber. The mass flow rate, discharge voltage, and applied magnetic field strength could be varied, allowing for erosion measurements over a broad thruster operating envelope. Results are presented demonstrating the ability of the REAST sensor to capture not only the insulator erosion rates but also changes in these rates as a function of the discharge parameters.

MoO2-ordered mesoporous carbon hybrids as anode materials with highly improved rate capability and reversible capacity for lithium-ion battery.

PubMed

Chen, Ailian; Li, Caixia; Tang, Rui; Yin, Longwei; Qi, Yongxin

2013-08-28

A novel hybrid of MoO2-ordered mesoporous carbon (MoO2-OMC) was prepared through a two-step solvothermal chemical reaction route. The electrochemical performances of the mesoporous MoO2-OMC hybrids were examined using galvanostatical charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) techniques. The MoO2-OMC hybrid exhibits significantly improved electrochemical performance of high reversible capacity, high-rate capability, and excellent cycling performance as an anode electrode material for Li ion batteries. It is revealed that the MoO2-OMC hybrid could deliver the first discharge capacity of 1641.8 mA h g(-1) with an initial Coulombic efficiency of 63.6%, and a reversible capacity as high as 1049.1 mA h g(-1) even after 50 cycles at a current density of 100 mA g(-1), much higher than the theoretical capacity of MoO2 (838 mA h g(-1)) and OMC materials. The MoO2-OMC hybrid demonstrates an excellent high rate capability with capacity of ∼600 mA h g(-1) even at a charge current density of 1600 mA g(-1) after 50 cycles, which is approximately 11.1 times higher than that of the OMC (54 mA h g(-1)) materials. The improved rate capability and reversible capacity of the MoO2-OMC hybrid are attributed to a synergistic reaction between the MoO2 nanoparticles and mesoporous OMC matrices. It is noted that the electrochemical performance of the MoO2-OMC hybrid is evidently much better than the previous MoO2-based hybrids.

Nanowire Heterostructures Comprising Germanium Stems and Silicon Branches as High-Capacity Li-Ion Anodes with Tunable Rate Capability.

PubMed

Kennedy, Tadhg; Bezuidenhout, Michael; Palaniappan, Kumaranand; Stokes, Killian; Brandon, Michael; Ryan, Kevin M

2015-07-28

Here we report the rational design of a high-capacity Li-ion anode material comprising Ge nanowires with Si branches. The unique structure provides an electrode material with tunable properties, allowing the performance to be tailored for either high capacity or high rate capability by controlling the mass ratio of Si to Ge. The binder free Si-Ge branched nanowire heterostructures are grown directly from the current collector and exhibit high capacities of up to ∼1800 mAh/g. Rate capability testing revealed that increasing the Ge content within the material boosted the performance of the anode at fast cycling rates, whereas a higher Si content was optimal at slower rates of charge and discharge. Using ex-situ electron microscopy, Raman spectroscopy and energy dispersive X-ray spectroscopy mapping, the composition of the material is shown to be transient in nature, transforming from a heterostructure to a Si-Ge alloy as a consequence of repeated lithiation and delithiation.

Performance and Safety Characteristics of Lithium-molybdenum Disulfide Cells

NASA Technical Reports Server (NTRS)

Stiles, J. A.

1984-01-01

The lithium-molybdenum disulfide system offers attractive characteristics including high rate capability, successful operation up to 75 C, a very low self-discharge rate, a good cycle life and safety characteristics which compare favorably to those of other lithium cells. Moreover, the materials and manufacturing costs for the system is effectively controlled, so the cells should ultimately be competitive with currently marketed rechargeable cells.

Li2.97Mg0.03VO4: High rate capability and cyclability performances anode material for rechargeable Li-ion batteries

NASA Astrophysics Data System (ADS)

Dong, Youzhong; Zhao, Yanming; Duan, He; Singh, Preetam; Kuang, Quan; Peng, Hongjian

2016-07-01

Mg-doped composite, Li2.97Mg0.03VO4, with an orthorhombic structure was prepared by a sol-gel method. The effects of the Mg doping on the structure and electrochemical performance of Li3VO4 were investigated. The X-ray diffraction pattern shows that the Mg doping does not change the crystal structure of Li3VO4. The EDS mappings indicated the fairly uniform distribution of Mg throughout the grains of Li2.97Mg0.03VO4. Electronic conductivity of Mg-doped Li3VO4 increased by two orders of magnitude compared to that of pure Li3VO4. CV and EIS measurement confirms that the Li2.97Mg0.03VO4 sample exhibits a smaller polarization and transfer resistance and a higher lithium diffusion coefficient compared with the pure Li3VO4. Due to the better electrochemical kinetics properties, Mg-doped Li3VO4 showed a significant improved performance compared to the pure Li3VO4, especially for the high rate capability. At the higher discharge/charge rate (2C), the discharge and charge capacities of 415.5 and 406.1 mAh/g have been obtained for the Li2.97Mg0.03VO4 which is more than three times higher the discharge/charge capacities of Li3VO4. The discharge and charge capacities of pure Li3VO4 are only 126.4 and 125.8 mAh/g respectively. The excellent electrochemical performance of Li2.97Mg0.03VO4 enables it as a promising anode material for rechargeable lithium-ion batteries.

Advanced space propulsion thruster research

NASA Technical Reports Server (NTRS)

Wilbur, P. J.

1981-01-01

Experiments showed that stray magnetic fields can adversely affect the capacity of a hollow cathode neutralizer to couple to an ion beam. Magnetic field strength at the neutralizer cathode orifice is a crucial factor influencing the coupling voltage. The effects of electrostatic accelerator grid aperture diameters on the ion current extraction capabilities were examined experimentally to describe the divergence, deflection, and current extraction capabilities of grids with the screen and accelerator apertures displaced relative to one another. Experiments performed in orificed, mercury hollow cathodes support the model of field enhanced thermionic electron mission from cathode inserts. Tests supported the validity of a thermal model of the cathode insert. A theoretical justification of a Saha equation model relating cathode plasma properties is presented. Experiments suggest that ion loss rates to discharge chamber walls can be controlled. A series of new discharge chamber magnetic field configurations were generated in the flexible magnetic field thruster and their effect on performance was examined. A technique used in the thruster to measure ion currents to discharge chamber walls is described. Using these ion currents the fraction of ions produced that are extracted from the discharge chamber and the energy cost of plasma ions are computed.

X-ray computed tomography comparison of individual and parallel assembled commercial lithium iron phosphate batteries at end of life after high rate cycling

NASA Astrophysics Data System (ADS)

Carter, Rachel; Huhman, Brett; Love, Corey T.; Zenyuk, Iryna V.

2018-03-01

X-ray computed tomography (X-ray CT) across multiple length scales is utilized for the first time to investigate the physical abuse of high C-rate pulsed discharge on cells wired individually and in parallel.. Manufactured lithium iron phosphate cells boasting high rate capability were pulse power tested in both wiring conditions with high discharge currents of 10C for a high number of cycles (up to 1200) until end of life (<80% of initial discharge capacity retained). The parallel assembly reached end of life more rapidly for reasons unknown prior to CT investigations. The investigation revealed evidence of overdischarge in the most degraded cell from the parallel assembly, compared to more traditional failure in the individual cell. The parallel-wired cell exhibited dissolution of copper from the anode current collector and subsequent deposition throughout the separator near the cathode of the cell. This overdischarge-induced copper deposition, notably impossible to confirm with other state of health (SOH) monitoring methods, is diagnosed using CT by rendering the interior current collector without harm or alteration to the active materials. Correlation of CT observations to the electrochemical pulse data from the parallel-wired cells reveals the risk of parallel wiring during high C-rate pulse discharge.

The electrochemical performance of aqueous rechargeable battery of Zn/Na0.44MnO2 based on hybrid electrolyte

NASA Astrophysics Data System (ADS)

Wu, Xianwen; Li, Yehua; Xiang, Yanhong; Liu, Zhixiong; He, Zeqiang; Wu, Xianming; Li, Youji; Xiong, Lizhi; Li, Chuanchang; Chen, Jian

2016-12-01

There is a broad application prospect for smart grid about aqueous rechargeable sodium-ion battery. In order to improve its electrochemical performance, a hybrid cationic aqueous-based rechargeable battery system based on the nanostructural Na0.44MnO2 and metallic zinc foil as the positive and negative electrodes respectively is built up. Nano rod-like Na0.44MnO2 is synthesized by sol-gel method followed by calcination at 850 °C for 9 h, and various characterization techniques including the X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to investigate the structure and morphology of the as-prepared material. The cyclic voltammetry, galvanostatic charge-discharge and self-discharge measurements are performed at the same time. The results show that the battery delivers a very high initial discharge capacity of 186.2 mAh g-1 at 0.2 C-rate in the range of 0.5-2.0 V, and it exhibits a discharge capacity of 113.3 mAh g-1 at high current density of 4 C-rate, indicative of excellent rate capability.

Performance and Safety Characteristics of Sanyo NiCd Cells

NASA Technical Reports Server (NTRS)

Deng, Yi; Jeevarajan, Judith; Bragg, Bobby; Zhang, Wenlin

2002-01-01

NiCd batteries are widely used for high drain applications like power tools and also in other portable equipment like cameras, PCs, etc. NASA and Dreamtime Holdings, Inc. worked together to have the capability of a High Definition TV (HDTV) on the ISS and Space Shuttle. The Sanyo HD camcorder was used on the STS 105 fight in July, 2001 . The camcorder used two versions of a NiCd battery. One was a cOlnmercial off-the-shelf Sony BP90 battery pack that had Sanyo NiCd D cells. The other was a modified battery (FBP-90) made by Frezzi Energy, which also had the same Sanyo NiCd D cells. The battery has 10 NiCd D cells in series to form a 12 V pack with 5.0 Ah capacity. Our current study involved the perforn1ance and abuse tests on the Sanyo NiCd 5.0 Ah D cells. The best combination of charge/discharge current rate is 0.3C for charge and 1/2e for discharge within 200 cycles. No significant changes in capacity were observed in 200 cycles. The cell also showed capability of 5C (25.0A) high rate discharge. In overcharge and overdischarge tests, all tested cells passed the tests without venting. In imbalance tests, the battery pack could be charged and discharged only at relatively low current. At charge current of 1.0A or less, the imbalanced cells in the battery pack displayed relatively high temperatures during charge or discharge. The cells functioned normally during internal short and no mishap occurred during external short. Cells passed exposure tests at 80 C and no leakage till 150 C during heat-tovent tests.

Brine reuse in ion-exchange softening: salt discharge, hardness leakage, and capacity tradeoffs.

PubMed

Flodman, Hunter R; Dvorak, Bruce I

2012-06-01

Ion-exchange water softening results in the discharge of excess sodium chloride to the aquatic environment during the regeneration cycle. In order to reduce sodium chloride use and subsequent discharge from ion-exchange processes, either brine reclaim operations can be implemented or salt application during regeneration can be reduced. Both result in tradeoffs related to loss of bed volumes treated per cycle and increased hardness leakage. An experimentally validated model was used to compare concurrent water softening operations at various salt application quantities with and without the direct reuse of waste brine for treated tap water of typical midwestern water quality. Both approaches were able to reduce salt use and subsequent discharge. Reducing salt use and discharge by lowering the salt application rate during regeneration consequently increased hardness leakage and decreased treatment capacity. Single or two tank brine recycling systems are capable of reducing salt use and discharge without increasing hardness leakage, although treatment capacity is reduced.

The fabrication of foam-like 3D mesoporous NiO-Ni as anode for high performance Li-ion batteries

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

Huang, Peng, E-mail: huangp07@lzu.edu.cn; Department of Physics, Lanzhou University, Lanzhou 730000; Zhang, Xin

2015-03-15

Graphical abstract: Foam-like 3 dimensional (3D) mesoporous NiO on 3D micro-porous Ni was fabricated. - Highlights: • We prepare NiO-Ni foam composite via hydrothermal etching and subsequent annealing. • The NiO exhibits novel foam-like 3D mesoporous architecture. • The NiO-Ni anode shows good cycle stability. - Abstract: Foam-like three dimensional mesoporous NiO on Ni foam was fabricated via facile hydrothermal etching and subsequent annealing treatment. The porous NiO consists of a large number of nanosheets with mean thickness about 50 nm, among which a large number of mesoscopic pores with size ranges from 100 nm to 1 μm distribute. Themore » electrochemical performance of the as-prepared NiO-Ni as anode for lithium ion battery was studied by conventional charge/discharge test, which shows excellent cycle stability and rate capability. It exhibits initial discharge and charge capacities of 979 and 707 mA h g{sup −1} at a charge/discharge rate of 0.7 C, which maintain of 747 and 738 mA h g{sup −1} after 100 cycles. Even after 60 cycles at various rates from 0.06 to 14 C, the 10th discharge and charge capacities of the NiO-Ni electrode can revert to 699 and 683 mA h g{sup −1} when lowering the charge/discharge rate to 0.06 C.« less

Surface charge dynamics and OH and H number density distributions in near-surface nanosecond pulse discharges at a liquid / vapor interface

NASA Astrophysics Data System (ADS)

Winters, Caroline; Petrishchev, Vitaly; Yin, Zhiyao; Lempert, Walter R.; Adamovich, Igor V.

2015-10-01

The present work provides insight into surface charge dynamics and kinetics of radical species reactions in nanosecond pulse discharges sustained at a liquid-vapor interface, above a distilled water surface. The near-surface plasma is sustained using two different discharge configurations, a surface ionization wave discharge between two exposed metal electrodes and a double dielectric barrier discharge. At low discharge pulse repetition rates (~100 Hz), residual surface charge deposition after the discharge pulse is a minor effect. At high pulse repetition rates (~10 kHz), significant negative surface charge accumulation over multiple discharge pulses is detected, both during alternating polarity and negative polarity pulse trains. Laser induced fluorescence (LIF) and two-photon absorption LIF (TALIF) line imaging are used for in situ measurements of spatial distributions of absolute OH and H atom number densities in near-surface, repetitive nanosecond pulse discharge plasmas. Both in a surface ionization wave discharge and in a double dielectric barrier discharge, peak measured H atom number density, [H] is much higher compared to peak OH number density, due to more rapid OH decay in the afterglow between the discharge pulses. Higher OH number density was measured near the regions with higher plasma emission intensity. Both OH and especially H atoms diffuse out of the surface ionization wave plasma volume, up to several mm from the liquid surface. Kinetic modeling calculations using a quasi-zero-dimensional H2O vapor / Ar plasma model are in qualitative agreement with the experimental data. The results demonstrate the experimental capability of in situ radical species number density distribution measurements in liquid-vapor interface plasmas, in a simple canonical geometry that lends itself to the validation of kinetic models.

High-rate lithium/manganese dioxide batteries; the double cell concept

NASA Astrophysics Data System (ADS)

Drews, Jürgen; Wolf, Rüdiger; Fehrmann, Gerd; Staub, Roland

An implantable defibrillator battery has to provide pulse-power capabilities as well as high energy density. Low self-discharge rates are mandatory and an ability to check the state of charge is required. To accomplish these requirements, a lithium/manganese dioxide battery with a modified active cathode mass has been developed. Usage of a double cell design increases significantly the battery performance within an implantable defibrillator. The design features of a high-rate, pulse-power, manganese dioxide double cell are described.

Structural Evolution of Li xNi yMn zCo 1-y-zO 2 Cathode Materials during High-Rate Charge and Discharge

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

Hwang, Sooyeon; Jo, Eunmi; Chung, Kyung Yoon

Ni-rich lithium transition metal oxides have received significant attention due to their high capacities and rate capabilities determined via theoretical calculations. Although the structural properties of these materials are strongly correlated with the electrochemical performance, their structural stability during the high-rate electrochemical reactions has not been fully evaluated yet. In this work, transmission electron microscopy is used to investigate the crystallographic and electronic structural modifications of Ni-based cathode materials at a high charge/discharge rate of 10 C. It is found that the high-rate electrochemical reactions induce structural inhomogeneity near the surface of Ni-rich cathode materials, which limits Li transport andmore » reduces their capacities. Furthermore, this study establishes a correlation between the high-rate electrochemical performance of the Ni-based materials and their structural evolution, which can provide profound insights for designing novel cathode materials having both high energy and power densities.« less

Structural Evolution of Li xNi yMn zCo 1-y-zO 2 Cathode Materials during High-Rate Charge and Discharge

DOE PAGES

Hwang, Sooyeon; Jo, Eunmi; Chung, Kyung Yoon; ...

2017-11-08

Ni-rich lithium transition metal oxides have received significant attention due to their high capacities and rate capabilities determined via theoretical calculations. Although the structural properties of these materials are strongly correlated with the electrochemical performance, their structural stability during the high-rate electrochemical reactions has not been fully evaluated yet. In this work, transmission electron microscopy is used to investigate the crystallographic and electronic structural modifications of Ni-based cathode materials at a high charge/discharge rate of 10 C. It is found that the high-rate electrochemical reactions induce structural inhomogeneity near the surface of Ni-rich cathode materials, which limits Li transport andmore » reduces their capacities. Furthermore, this study establishes a correlation between the high-rate electrochemical performance of the Ni-based materials and their structural evolution, which can provide profound insights for designing novel cathode materials having both high energy and power densities.« less

Three-Dimensional Porous Iron Vanadate Nanowire Arrays as a High-Performance Lithium-Ion Battery.

PubMed

Cao, Yunhe; Fang, Dong; Liu, Ruina; Jiang, Ming; Zhang, Hang; Li, Guangzhong; Luo, Zhiping; Liu, Xiaoqing; Xu, Jie; Xu, Weilin; Xiong, Chuanxi

2015-12-23

Development of three-dimensional nanoarchitectures on current collectors has emerged as an effective strategy for enhancing rate capability and cycling stability of the electrodes. Herein, a new type of three-dimensional porous iron vanadate (Fe0.12V2O5) nanowire arrays on a Ti foil has been synthesized by a hydrothermal method. The as-prepared Fe0.12V2O5 nanowires are about 30 nm in diameter and several micrometers in length. The effect of reaction time on the resulting morphology is investigated and the mechanism for the nanowire formation is proposed. As an electrode material used in lithium-ion batteries, the unique configuration of the Fe0.12V2O5 nanowire arrays presents enhanced capacitance, satisfying rate capability and good cycling stability, as evaluated by cyclic voltammetry and galvanostatic discharge-charge cycling. It delivers a high discharge capacity of 293 mAh·g(-1) at 2.0-3.6 V or 382.2 mAh·g(-1) at 1.0-4.0 V after 50 cycles at 30 mA·g(-1).

Multi-timescale power and energy assessment of lithium-ion battery and supercapacitor hybrid system using extended Kalman filter

NASA Astrophysics Data System (ADS)

Wang, Yujie; Zhang, Xu; Liu, Chang; Pan, Rui; Chen, Zonghai

2018-06-01

The power capability and maximum charge and discharge energy are key indicators for energy management systems, which can help the energy storage devices work in a suitable area and prevent them from over-charging and over-discharging. In this work, a model based power and energy assessment approach is proposed for the lithium-ion battery and supercapacitor hybrid system. The model framework of the lithium-ion battery and supercapacitor hybrid system is developed based on the equivalent circuit model, and the model parameters are identified by regression method. Explicit analyses of the power capability and maximum charge and discharge energy prediction with multiple constraints are elaborated. Subsequently, the extended Kalman filter is employed for on-board power capability and maximum charge and discharge energy prediction to overcome estimation error caused by system disturbance and sensor noise. The charge and discharge power capability, and the maximum charge and discharge energy are quantitatively assessed under both the dynamic stress test and the urban dynamometer driving schedule. The maximum charge and discharge energy prediction of the lithium-ion battery and supercapacitor hybrid system with different time scales are explored and discussed.

Effect of Carbon Coating on Li4TiO12 of Anode Material for Hybrid Capacitor.

PubMed

Lee, Jong-Kyu; Lee, Byung-Gwan; Yoon, Jung-Rag

2015-11-01

The carbon-coated Li4Ti5O12 of anode material for hybrid capacitor was prepared by controlling carbonization time at 700 degrees C in nitrogen. With increasing of carbonization time, the discharge capacity and capacitance were decreased, while the equivalent series resistance was not changed remarkably. The rate capability and cycle performance of carbon-coated Li4Ti5O12 were larger than that of Li4Ti5O12. Carbon coating improved conductivity as well as Li-ion diffusion, and thus also resulted in good rate capabilities and cycle stability. The effects of carbon coating on the gas generation of hybrid capacitor were also discussed.

Aerosol-assisted chemical vapor deposition of V2O5 cathodes with high rate capabilities for magnesium-ion batteries

NASA Astrophysics Data System (ADS)

Drosos, Charalampos; Jia, Chenglin; Mathew, Shiny; Palgrave, Robert G.; Moss, Benjamin; Kafizas, Andreas; Vernardou, Dimitra

2018-04-01

The growth of orthorhombic vanadium pentoxide nanostructures was accomplished using an aerosol-assisted chemical vapor deposition process. These materials showed excellent electrochemical performance for magnesium-ion storage in an aqueous electrolyte; showing specific discharge capacities of up to 427 mAh g-1 with a capacity retention of 82% after 2000 scans under a high specific current of 5.9 A g-1. The high rate capability suggested good structural stability and high reversibility. We believe the development of low-cost and large-area coating methods, such as the technique used herein, will be essential for the upscalable fabrication of next-generation rechargeable battery technologies.

Ti n O2n-1-Coated Li4Ti5O12 Composite Anode Material for Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Zhang, Xiaoyan; Xu, Wen; Liu, Wanying; Li, Xing; Zhong, Xiaoxi; Lin, Yuanhua

2018-01-01

In an effort to enhance the rate capability of Li4Ti5O12, the Ti n O2n-1-coated Li4Ti5O12 (Li4Ti5O12-Ti n O2n-1, 3 < n < 10) composite has been synthesized through a sol-gel process followed by heat treatment in H2 atmosphere. Compared with pure Li4Ti5O12, Li4Ti5O12-Ti n O2n-1 composite shows higher specific capacity, better rate capability and cycle stability. The initial discharge capacity of the Li4Ti5O12-Ti n O2n-1 composite electrode is 171.2 mAh g-1 at 0.2°C, and 103.8 mAh g-1 at 20°C. Moreover, the discharge capacity remains 79.5 mAh g-1 after 100 cycles at 20°C with a capacity loss of 23.4%. The improved rate capacity and cycling stability clarify the positive effects of Ti n O2n-1 coating layer in Li4Ti5O12-Ti n O2n-1 composite as an anode material for lithium ion batteries.

Studies of oxygen-helium discharges for use in electric oxygen-iodine lasers

NASA Astrophysics Data System (ADS)

Zimmerman, Joseph William

In recent work, the performance of the Electric Oxygen-Iodine Laser (ElectricOIL), developed in partnership by researchers at the University of Illinois and CU Aerospace, has been greatly improved through systematic study of various components of this new laser technology. One major contribution to the advancement of ElectricOIL technology has been the development of electric discharges capable of producing significant flow rates of the precursor electronically-excited molecular oxygen, O2(a1Delta). O2(a 1Delta) serves as an energy reservoir in the laser system, pumping atomic iodine by near-resonant energy transfer producing gain and laser on the I(2P1/2) → I(2P3/2 ) transition at 1315 nm. Initial experimental work with radio-frequency discharges showed the importance of controlling O-atom flow rates to reduce quenching losses of energy stored in O2(a1Delta), and determined proper selection of the helium diluent ratio and specific power deposition (power per O2 flow rate). Further experimental investigations with transverse capacitive radio-frequency discharges in O2/He/NO mixtures in the pressure range of 1-100 Torr and power range of 0.1-1.2 kW have indicated that O2(a1Delta) production is a strong function of geometry (transverse gap), excitation frequency, and pressure. These parameters along with gas flow mixture dictate the current density at which the discharge operates, and its modal characteristics (normal vs. abnormal, homogeneous vs. inhomogeneous). A key result is that to encourage efficient O2(a1Delta) production these parameters should be selected in order to promote a homogeneous (low current density) discharge. The discharge behavior is characterized using terminal current-voltage-characteristics, microwave interferometer measurements, and plasma emission intensity measurements. Numerous spectroscopic measurements of O2(a1Delta), oxygen atoms, and discharge excited states are made in order to describe the discharge performance dependent on various parameters. The influence of NO on O-atom flow rates and O2(a1Delta) production is investigated. Progress of laser power extraction since initial reports in 2005 is overviewed.

High Rate Oxygen Reduction in Non-aqueous Electrolytes with the Addition of Perfluorinated Additives

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

Wang, Y.; Yang, X.; Zheng, D.

2011-08-04

The discharge rate capability of Li-air batteries is substantially increased by using perfluorinated compounds as oxygen carriers. The solubility of oxygen in a non-aqueous electrolyte can be significantly increased by the introduction of such compounds, which leads to the increase in the diffusion-limited current of oxygen reduction on the gas diffusion electrode in a Li-air battery. The perfluorinated compound is found to be stable within the electrochemical window of the electrolyte. A powder microelectrode and a rotating disk electrode were used to study the gas diffusion-limited current together with a rotating disk electrode. A 5 mA cm{sup -2} discharge ratemore » is demonstrated in a lab Li-O{sub 2} cell.« less

Characteristics of 2-heptanone decomposition using nanosecond pulsed discharge plasma

NASA Astrophysics Data System (ADS)

Nakase, Yuki; Fukuchi, Yuichi; Wang, Douyan; Namihira, Takao; Akiyama, Hidenori; Kumamoto University Collaboration

2015-09-01

Volatile organic compounds (VOC) evaporate at room temperature. VOCs typically consist of toluene, benzene and ethyl acetate, which are used in cosmetics, dry cleaning products and paints. Exposure to elevated levels of VOCs may cause headaches, dizziness and irritation to the eyes, nose, and throat; they may also cause environmental problems such as air pollution, acid rain and photochemical smog. As such, they require prompt removal. Nanosecond pulsed discharge is a kind of non-thermal plasma consisting of a streamer discharge. Several advantages of nanosecond pulsed discharge plasma have been demonstrated by studies of our research group, including low heat loss, highly energetic electron generation, and the production of highly active radicals. These advantages have shown ns pulsed discharge plasma capable of higher energy efficiency for processes, such as air purification, wastewater treatment and ozone generation. In this research, nanosecond pulsed discharge plasma was employed to treat 2-heptanone, which is a volatile organic compound type and presents several harmful effects. Characteristics of treatment dependent on applied voltage, gas flow rate and input energy density were investigated. Furthermore, byproducts generated by treatment were also investigated.

Fabrication of Na0.7MnO2/C composite cathode material by simple heat treatment for high-power na-ion batteries

NASA Astrophysics Data System (ADS)

Sohn, DongRak; Lim, Sung-Jin; Nam, Do-Hwan; Hong, Kyung-Sik; Kim, Tae-Hee; Oh, SeKwon; Eom, Ji-Yong; Cho, EunAe; Kwon, HyukSang

2018-01-01

A Na0.7MnO2/C composite cathode material is synthesized by simple and costeffective two-step heat treatment for an improvement in the rate capability of Na0.7MnO2. The first heat treatment is to synthesize Na0.7MnO2, and the second one is a low temperature annealing at 350 °C for 1 h in air, which is necessary to suppress an interfacial reaction between the Na0.7MnO2 and C in the synthesis process of Na0.7MnO2/C composite. Structural analyses by XRD and XPS reveal that the Na0.7MnO2/C shows the same structural properties as that of the pristine Na0.7MnO2, and hence they exhibit the same initial discharge capacity of 175 mAh g-1 at 20 mA g-1. At a current density of 400 mA g-1, the discharge capacity of Na0.7MnO2 reduces to 50 mAh g-1 (28% of the initial discharge capacity), whereas that of Na0.7MnO2/C reduces to 108 mAh g-1 (61% of the initial discharge capacity). The enhanced rate capability of the Na0.7MnO2/C is attributed to the conductive carbon layer formed on the surface of Na0.7MnO2 particles, enabling the facile transport of electrons from the current collector to the surface of the Na0.7MnO2 particles. [Figure not available: see fulltext.

Synthesis, characterization and rate capability performance of the micro-porous MnO{sub 2} nanowires as cathode material in lithium batteries

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

R, Ranjusha; S, Sonia T.; S, Roshny

Graphical abstract: Translating MnO{sub 2} nanowires as cathode materials in coin cell and studying their discharge behavior and cycling stability at different C-rates. - Highlights: • MnO{sub 2} nanowires have been synthesized via hydrothermal route. • The nanowires were employed as cathode materials in Li-batteries. • Discharge and cycling stability were studied at different C-rates. • Specific capacity and power density of 251 mAh g{sup −1} and 200 W kg{sup −1} were attained. - Abstract: A peculiar architecture of one-dimensional MnO{sub 2} nanowires was synthesized by an optimized hydrothermal route and has been lucratively exploited to fabricate highly efficient microporousmore » electrode overlays for lithium batteries. These fabricated electrodes comprised of interconnected nanoscale units with wire-shaped profile which exhibits high aspect ratio in the order of 10{sup 2}. Their outstanding intercalation/de-intercalation prerogatives have also been studied to fabricate lithium coin cells which revealed a significant specific capacity and power density of 251 mAh g{sup −1} and 200 W kg{sup −1}, respectively. A detailed electrochemical study was performed to elucidate how surface morphology and redox reaction behaviors underlying these electrodes influence the cyclic behavior of the electrode. Rate capability tests at different C-rates were performed to evaluate the capacity and cycling performance of these coin cells.« less

Manufacture and evaluation of Li/BCX DD cells

NASA Technical Reports Server (NTRS)

Meyer, S.; Takeuchi, E.

1990-01-01

This project is divided into four main tasks: cell manufacture, acceptance, and lot certification of cells, performance testing of cells, and abuse testing of cells. Lithium/bromine chloride in thionyl chloride (Li/BCX) 149 DD cells (PN 3B2085-XA) were built according to the provisions of Electrochem Industries Quality Plan 17096. Acceptance and lot certification testing was performed according to NASA JSC Document EP5-83-025, Revision B. Acceptance testing included open circuit and load voltage check, visual examination, size and weight measurements, and high temperature exposure. Lot certification tests were performed for capacity performance and for performance under conditions of thermal and electrical abuse. These tests included 149 C exposure, capacity discharge, fuse check, high temperature exposure, high rate discharge, short circuit, vibration, and overdischarge testing. A quantity of 200 cells was delivered to Johnson Space Center for life test evaluation. A parametric evaluation of the capacity discharge of Li/BCX DD cells was performed over a variety of temperatures and discharge rates. This testing served to map the performance capability of the cell. Tests were also performed over a variety of electrical and thermal abuse conditions. Abuse tests included short circuit, charging, overdischarge, high temperature exposure, shock, and vibration.

Development of Resistive Micromegas for Sampling Calorimetry

NASA Astrophysics Data System (ADS)

Geralis, T.; Fanourakis, G.; Kalamaris, A.; Nikas, D.; Psallidas, A.; Chefdeville, M.; Karyotakis, I.; Koletsou, I.; Titov, M.

2018-02-01

Resistive micromegas is proposed as an active element for sampling calorimetry. Future linear collider experiments or the HL-LHC experiments can profit from those developments for Particle Flow Calorimetry. Micromegas possesses remarkable properties concerning gain stability, reduced ion feedback, response linearity, adaptable sensitive element granularity, fast response and high rate capability. Recent developments on Micromegas with a protective resistive layer present excellent results, resolving the problem of discharges caused by local high charge deposition, thanks to its RC-slowed charge evacuation. Higher resistivity though, may cause loss of the response linearity at high rates. We have scanned a wide range of resistivities and performed laboratory tests with X-rays that demonstrate excellent response linearity up to rates of (a few) times 10MHz/cm2, with simultaneous mitigation of discharges. Beam test studies at SPS/CERN with hadrons have also shown a remarkable stability of the resistive Micromegas and low currents for rates up to 15MHz/cm2. We present results from the aforementioned studies confronted with MC simulation

High-performance tin oxide-nitrogen doped graphene aerogel hybrids as anode materials for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Tan, Chunhui; Cao, Jing; Khattak, Abdul Muqsit; Cai, Feipeng; Jiang, Bo; Yang, Gai; Hu, Suqin

2014-12-01

Tin dioxide nanoparticles on nitrogen doped graphene aerogel (SnO2-NGA) hybrid are synthesized by one-step hydrothermal method and successfully applied in lithium-ion batteries as a free-standing anode. The electrochemical performance of SnO2-NGA hybrid is investigated by galvanostatic charge-discharge cycling, rate capability test, cyclic voltammetry and electrochemical impedance spectroscopy. It is found that the SnO2-NGA hybrid with freestanding spongy-like structure exhibit remarkable lithium storage capacity (1100 mAh g-1 after 100 cycles), good cycling stability and high rate capability. The outstanding performance is attributed to the uniform SnO2 nanoparticles, unique spongy-like structure and N doping defect for Li+ diffusion.

Enhancing the electrochemical performance of Li-rich layered oxide Li1.13Ni0.3Mn0.57O2 via WO3 doping and accompanying spontaneous surface phase formation

NASA Astrophysics Data System (ADS)

Huang, Jiajia; Liu, Haodong; Hu, Tao; Meng, Ying Shirley; Luo, Jian

2018-01-01

WO3 doping and accompanying spontaneous formation of a surface phase can substantially improve the discharge capacity, rate capability, and cycling stability of Co-free Li-rich layered oxide Li1.13Ni0.3Mn0.57O2 cathode material. X-ray photoelectron spectroscopy, in conjunction with ion sputtering, shows that W segregates to the particle surfaces, decreases the surface Ni/Mn ratio, and changes the surface valence state. High-resolution transmission electron microscopy further suggests that W segregation increases surface structural disorder. The spontaneous and simultaneous changes in the surface structure, composition, and valence state represent the formation of a surface phase (complexion) as the preferred surface thermodynamic state. Consequently, the averaged discharge capacity is increased by ∼13% from 251 to 284 mAh g-1 at a low rate of C/20 and by ∼200% from 30 to 90 mAh g-1 at a high rate of 40C, in comparison with an undoped specimen processed under identical conditions. Moreover, after 100 cycles at a charge/discharge rate of 1C, the WO3 doped specimen retained a discharge capacity of 188 mAh g-1, being 27% higher than that of the undoped specimen. In a broader context, this work exemplifies an opportunity of utilizing spontaneously-formed surface phases as a scalable and cost-effective method to improve materials properties.

Enabling high rate charge and discharge capability, low internal resistance, and excellent cycleability for Li-ion batteries utilizing graphene additives

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

Tsai, Hsiu-Ling; Hsieh, Chien-Te; Li, Jianlin

A liquid-phase mixing method is adopted to uniformly disperse the graphene nanosheets onto LiNi 1/3Co 1/3Mn 1/3O 2 cathode for high-performance Li-ion batteries (LIBs). The electrochemical performance was characterized using a full pouch cells with state-of-the-art electrode areal loading (compared to half coin cells). The addition of graphene sheets (i.e., only 1 wt%) significantly improves the high rate capability for charging and discharging operation. For example, 6 times improvement in 5 C charging was achieved providing further insights in enabling extreme fast charging for LIBs. Other benefits include longer cycleability, lower internal resistance, and higher lithium ion diffusion coefficient, demonstratedmore » by charge-discharge cycling tests and electrochemical impedance spectroscopy. Higher capacity retention of 88.2% and decreased internal resistance of ~0.9 Ω are observed after 400 cycles. The diffusion coefficient of Li ions is 6.49 × 10 -8 cm 2 s -1 when charged to 4.2 V, which is approximately 1.37 times higher compared to the configuration with no graphene sheet (4.74 × 10 -8 cm 2 s -1). To conclude, the improved performance is ascribed to a robust network among the active materials formed by graphene sheets, which serves as an extended current conductor and facilitates charge transfer, ionic reversibility, and ionic transportation.« less

Enabling high rate charge and discharge capability, low internal resistance, and excellent cycleability for Li-ion batteries utilizing graphene additives

DOE PAGES

Tsai, Hsiu-Ling; Hsieh, Chien-Te; Li, Jianlin; ...

2018-03-27

A liquid-phase mixing method is adopted to uniformly disperse the graphene nanosheets onto LiNi 1/3Co 1/3Mn 1/3O 2 cathode for high-performance Li-ion batteries (LIBs). The electrochemical performance was characterized using a full pouch cells with state-of-the-art electrode areal loading (compared to half coin cells). The addition of graphene sheets (i.e., only 1 wt%) significantly improves the high rate capability for charging and discharging operation. For example, 6 times improvement in 5 C charging was achieved providing further insights in enabling extreme fast charging for LIBs. Other benefits include longer cycleability, lower internal resistance, and higher lithium ion diffusion coefficient, demonstratedmore » by charge-discharge cycling tests and electrochemical impedance spectroscopy. Higher capacity retention of 88.2% and decreased internal resistance of ~0.9 Ω are observed after 400 cycles. The diffusion coefficient of Li ions is 6.49 × 10 -8 cm 2 s -1 when charged to 4.2 V, which is approximately 1.37 times higher compared to the configuration with no graphene sheet (4.74 × 10 -8 cm 2 s -1). To conclude, the improved performance is ascribed to a robust network among the active materials formed by graphene sheets, which serves as an extended current conductor and facilitates charge transfer, ionic reversibility, and ionic transportation.« less

Potential effects of timber harvest and water management on streamflow dynamics and sediment transport

Treesearch

C. A. Troendle; W. K. Olsen

1994-01-01

The sustainability of aquatic and riparian ecological systems is strongly tied to the dynamics of the streamflow regime. Timber harvest can influence the flow regime by increasing total flow, altering peak discharge rate, and changing the duration of flows of differing frequency of occurrence. These changes in the energy and sediment transporting capability of the...

Facile Synthesis of SiO2@C Nanoparticles Anchored on MWNT as High-Performance Anode Materials for Li-ion Batteries.

PubMed

Zhao, Yan; Liu, Zhengjun; Zhang, Yongguang; Mentbayeva, Almagul; Wang, Xin; Maximov, M Yu; Liu, Baoxi; Bakenov, Zhumabay; Yin, Fuxing

2017-12-01

Carbon-coated silica nanoparticles anchored on multi-walled carbon nanotubes (SiO 2 @C/MWNT composite) were synthesized via a simple and facile sol-gel method followed by heat treatment. Scanning and transmission electron microscopy (SEM and TEM) studies confirmed densely anchoring the carbon-coated SiO 2 nanoparticles onto a flexible MWNT conductive network, which facilitated fast electron and lithium-ion transport and improved structural stability of the composite. As prepared, ternary composite anode showed superior cyclability and rate capability compared to a carbon-coated silica counterpart without MWNT (SiO 2 @C). The SiO 2 @C/MWNT composite exhibited a high reversible discharge capacity of 744 mAh g -1 at the second discharge cycle conducted at a current density of 100 mA g -1 as well as an excellent rate capability, delivering a capacity of 475 mAh g -1 even at 1000 mA g -1 . This enhanced electrochemical performance of SiO 2 @C/MWNT ternary composite anode was associated with its unique core-shell and networking structure and a strong mutual synergistic effect among the individual components.

1-Dimensional AgVO3 nanowires hybrid with 2-dimensional graphene nanosheets to create 3-dimensional composite aerogels and their improved electrochemical properties

NASA Astrophysics Data System (ADS)

Liang, Liying; Xu, Yimeng; Lei, Yong; Liu, Haimei

2014-03-01

Three-dimensional (3D) porous composite aerogels have been synthesized via an innovative in situ hydrothermal method assisted by a freeze-drying process. In this hybrid structure, one-dimensional (1D) AgVO3 nanowires are uniformly dispersed on two-dimensional (2D) graphene nanosheet surfaces and/or are penetrated through the graphene sheets, forming 3D porous composite aerogels. As cathode materials for lithium-ion batteries, the composite aerogels exhibit high discharge capacity, excellent rate capability, and good cycling stability.Three-dimensional (3D) porous composite aerogels have been synthesized via an innovative in situ hydrothermal method assisted by a freeze-drying process. In this hybrid structure, one-dimensional (1D) AgVO3 nanowires are uniformly dispersed on two-dimensional (2D) graphene nanosheet surfaces and/or are penetrated through the graphene sheets, forming 3D porous composite aerogels. As cathode materials for lithium-ion batteries, the composite aerogels exhibit high discharge capacity, excellent rate capability, and good cycling stability. Electronic supplementary information (ESI) available: Preparation, characterization, SEM images, XRD patterns, and XPS of AgVO3/GAs. See DOI: 10.1039/c3nr06899d

Binder-free flexible LiMn2O4/carbon nanotube network as high power cathode for rechargeable hybrid aqueous battery

NASA Astrophysics Data System (ADS)

Zhu, Xiao; Wu, Xianwen; Doan, The Nam Long; Tian, Ye; Zhao, Hongbin; Chen, P.

2016-09-01

Highly flexible LiMn2O4/carbon nanotube (CNT) electrodes are developed and used as a high power cathode for the Rechargeable Hybrid Aqueous Battery (ReHAB). LiMn2O4 particles are entangled into CNT networks, forming a self-supported free-standing hybrid films. Such hybrid films can be used as electrodes of ARLB without using any additional binders. The binder-free LiMn2O4/CNT electrode exhibits good mechanical properties, high conductivity, and effective charge transport. High-rate capability and high cycling stability are obtained. Typically, the LiMn2O4/CNT electrode achieves a discharge capacity of 72 mAh g-1 at the large-current of 20 C (1 C = 120 mAh g-1), and exhibits good cycling performance and high reversibility: Coulombic efficiency of almost 100% over 300 charge-discharge cycles at 4 C. By reducing the weight, and improving the large-current rate capability simultaneously, the LiMn2O4/CNT electrode can highly enhance the energy/power density of ARLB and hold potential to be used in ultrathin, lightweight electronic devices.

Facile Synthesis of SiO2@C Nanoparticles Anchored on MWNT as High-Performance Anode Materials for Li-ion Batteries

NASA Astrophysics Data System (ADS)

Zhao, Yan; Liu, Zhengjun; Zhang, Yongguang; Mentbayeva, Almagul; Wang, Xin; Maximov, M. Yu.; Liu, Baoxi; Bakenov, Zhumabay; Yin, Fuxing

2017-07-01

Carbon-coated silica nanoparticles anchored on multi-walled carbon nanotubes (SiO2@C/MWNT composite) were synthesized via a simple and facile sol-gel method followed by heat treatment. Scanning and transmission electron microscopy (SEM and TEM) studies confirmed densely anchoring the carbon-coated SiO2 nanoparticles onto a flexible MWNT conductive network, which facilitated fast electron and lithium-ion transport and improved structural stability of the composite. As prepared, ternary composite anode showed superior cyclability and rate capability compared to a carbon-coated silica counterpart without MWNT (SiO2@C). The SiO2@C/MWNT composite exhibited a high reversible discharge capacity of 744 mAh g-1 at the second discharge cycle conducted at a current density of 100 mA g-1 as well as an excellent rate capability, delivering a capacity of 475 mAh g-1 even at 1000 mA g-1. This enhanced electrochemical performance of SiO2@C/MWNT ternary composite anode was associated with its unique core-shell and networking structure and a strong mutual synergistic effect among the individual components.

Large springs of east Tennessee

USGS Publications Warehouse

Sun, Pao-chang P.; Criner, J.H.; Poole, J.L.

1963-01-01

Springs constitute an important source of water in east Tennessee, and many individual springs are capable of supplying the large quantities needed for municipal and industrial supplies. Most of the springs in east Tennessee issue from solution openings and fractured and faulted zones in limestone and dolomite of the Knox Group, Chickamauga Limestone, and Conasauga Group. The ability of these rocks to yield a sustained flow of water to springs is dependent on a system of interconnected openings through which water can infiltrate from the land surface and move to points of natural discharge. Ninety springs were selected for detailed study, and 84 of these are analyzed in terms of magnitude and variability of discharge. Of the 84 springs analyzed, 4 flow at an average rate of 10 to 100 cfs (cubic feet per second), 62 at an average rate of 1 to 10 cfs, and 18 at an average rate of 1 cfs or less. Of the 90 springs, 75 are variable in their discharge; that is, the ratio of their fluctuations to their average discharges exceeds 100 percent. Mathematical analysis of the flow recession curve of Mill Spring near Jefferson City shows that the hydrologic system contributing to the flow of the spring has an effective capacity of about 70 million cubic feet of water. The rate of depletion of this volume of water, in the absence of significant precipitation, averages 0.0056 cfs per day between the time when the hydrologic system is full and the time when the spring ceases to flow. From such a curve it is possible to determine at any time the residual volume of water remaining in the system and the expected rate of decrease in discharge from that time to cessation of flow. Correlation of discharge measurements of 22 springs with those of Mill Spring shows that rough approximations of discharge can be projected for springs for which few measurements are available. Seventeen of the springs analyzed in this manner show good correlation with Mill Spring: that is, their coefficients of correlation were 0.70 or better as compared with a perfect correlation factor of 1.00.

High-Energy-Density, Low-Temperature Li/CFx Primary Cells

NASA Technical Reports Server (NTRS)

Whitacre, Jay; Bugga, Ratnakumar; Smart, Marshall; Prakash, G.; Yazami, Rachid

2007-01-01

High-energy-density primary (nonrechargeable) electrochemical cells capable of relatively high discharge currents at temperatures as low as -40 C have been developed through modification of the chemistry of commercial Li/CFx cells and batteries. The commercial Li/CFx units are not suitable for high-current and low-temperature applications because they are current limited and their maximum discharge rates decrease with decreasing temperature. The term "Li/CFx" refers to an anode made of lithium and a cathode made of a fluorinated carbonaceous material (typically graphite). In commercial cells, x typically ranges from 1.05 to 1.1. This cell composition makes it possible to attain specific energies up to 800 Wh/kg, but in order to prevent cell polarization and the consequent large loss of cell capacity, it is typically necessary to keep discharge currents below C/50 (where C is numerically equal to the current that, flowing during a charge or discharge time of one hour, would integrate to the nominal charge or discharge capacity of a cell). This limitation has been attributed to the low electronic conductivity of CFx for x approx. 1. To some extent, the limitation might be overcome by making cathodes thinner, and some battery manufacturers have obtained promising results using thin cathode structures in spiral configurations. The present approach includes not only making cathodes relatively thin [.2 mils (.0.051 mm)] but also using sub-fluorinated CFx cathode materials (x < 1) in conjunction with electrolytes formulated for use at low temperatures. The reason for choosing sub-fluorinated CFx cathode materials is that their electronic conductivities are high, relative to those for which x > 1. It was known from recent prior research that cells containing sub-fluorinated CFx cathodes (x between 0.33 and 0.66) are capable of retaining substantial portions of their nominal low-current specific energies when discharged at rates as high as 5C at room temperature. However, until experimental cells were fabricated following the present approach and tested, it was not known whether or to what extent low-temperature performance would be improved.

Probing the Complexities of Structural Changes in Layered Oxide Cathode Materials for Li-Ion Batteries during Fast Charge-Discharge Cycling and Heating.

PubMed

Hu, Enyuan; Wang, Xuelong; Yu, Xiqian; Yang, Xiao-Qing

2018-02-20

The rechargeable lithium-ion battery (LIB) is the most promising energy storage system to power electric vehicles with high energy density and long cycling life. However, in order to meet customers' demands for fast charging, the power performances of current LIBs need to be improved. From the cathode aspect, layer-structured cathode materials are widely used in today's market and will continue to play important roles in the near future. The high rate capability of layered cathode materials during charging and discharging is critical to the power performance of the whole cell and the thermal stability is closely related to the safety issues. Therefore, the in-depth understanding of structural changes of layered cathode materials during high rate charging/discharging and the thermal stability during heating are essential in developing new materials and improving current materials. Since structural changes take place from the atomic level to the whole electrode level, combination of characterization techniques covering multilength scales is quite important. In many cases, this means using comprehensive tools involving diffraction, spectroscopy, and imaging to differentiate the surface from the bulk and to obtain structural/chemical information with different levels of spatial resolution. For example, hard X-ray spectroscopy can yield the bulk information and soft X-ray spectroscopy can give the surface information; X-ray based imaging techniques can obtain spatial resolution of tens of nanometers, and electron-based microcopy can go to angstroms. In addition to challenges associated with different spatial resolution, the dynamic nature of structural changes during high rate cycling and heating requires characterization tools to have the capability of collecting high quality data in a time-resolved fashion. Thanks to the advancement in synchrotron based techniques and high-resolution electron microscopy, high temporal and spatial resolutions can now be achieved. In this Account, we focus on the recent works studying kinetic and thermal properties of layer-structured cathode materials, especially the structural changes during high rate cycling and the thermal stability during heating. Advanced characterization techniques relating to the rate capability and thermal stability will be introduced. The different structure evolution behavior of cathode materials cycled at high rate will be compared with that cycled at low rate. Different response of individual transition metals and the inhomogeneity in chemical distribution will be discussed. For the thermal stability, the relationship between structural changes and oxygen release will be emphatically pointed out. In all these studies being reviewed, advanced characterization techniques are critically applied to reveal complexities at multiscale in layer-structured cathode materials.

Moderate temperature rechargeable sodium batteries

NASA Technical Reports Server (NTRS)

Abraham, K. M.; Rupich, M. W.; Pitts, L.; Elliott, J. E.

1983-01-01

Cells utilizing the organic electrolyte, NaI in triglyme, operated at approx. 130 C with Na(+) - intercalating cathodes. However, their rate and stability were inadequate. NaAlCl4 was found to be a highly useful electrolyte for cell operation at 165-190 C. Na(+) intercalating chalcogenides reacted with NaAlCl4 during cycling to form stable phases. Thus, VS2 became essentially VS2Cl, with reversible capacity of approx 2.8 e(-)/V, and a mid-discharge voltage of approx 2.5V and 100 deep discharge cycles were readily achieved. A positive electrode consisting of VCl3 and S plus NaAlCl4 was subjected to deep-discharge cycles 300 times and it demonstrated identity with the in-situ-formed BSxCly cathode. NiS2 and NiS which are not Na(+)-intercalating structures formed highly reversible electrodes in NaAlCl4. The indicated discharge mechanism implies a theoretical capacity 4e(-)/Ni for NiS2 and 2e(-)/Ni for NiS. The mid-discharge potentials are, respectively, 2.4V and 2.1V. A Na/NiS2 cell cycling at a C/5 rate has exceeded 500 deep discharge cycles with 2.5e(-)/Ni average utilization. A 4 A-hr nominal capacity prototype Na/NiS2 cell was tested at 190 C. It was voluntarily terminated after 80 cycles. Further development, particularly of cathode structure and hardware should produce a battery capable of at least 50-W-hr/lb and more than 1000 cycles.

Enhanced Performance of "Flower-like" Li4Ti5O12 Motifs as Anode Materials for High-Rate Lithium-Ion Batteries.

PubMed

Wang, Lei; Zhang, Yiman; Scofield, Megan E; Yue, Shiyu; McBean, Coray; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S; Wong, Stanislaus S

2015-10-12

"Flower-like" motifs of Li4Ti5O12 were synthesized by using a facile and large-scale hydrothermal process involving unique Ti foil precursors followed by a short, relatively low-temperature calcination in air. Moreover, a detailed time-dependent growth mechanism and a reasonable reaction scheme were proposed to clearly illustrate and highlight the structural evolution and subsequent formation of this material. Specifically, the resulting "flower-like" Li4Ti5O12 microspheres consisting of thin nanosheets provide for an enhanced surface area and a reduced lithium-ion diffusion distance. The high surface areas of the exposed roughened, thin petal-like component nanosheets are beneficial for the interaction of the electrolyte with Li4Ti5O12 , which thereby ultimately provides for improved high-rate performance and favorable charge/discharge dynamics. Electrochemical studies of the as-prepared nanostructured Li4Ti5O12 clearly revealed their promising potential as an enhanced anode material for lithium-ion batteries, as they present both excellent rate capabilities (delivering 148, 141, 137, 123, and 60 mAh g(-1) under discharge rates of 0.2, 10, 20, 50, and 100 C, at cycles of 50, 55, 60, 65, and 70, respectively) and stable cycling performance (exhibiting a capacity retention of ≈97 % from cycles 10-100, under a discharge rate of 0.2 C, and an impressive capacity retention of ≈87 % by using a more rigorous discharge rate of 20 C from cycles 101-300). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deep Discharge Reconditioning and Shorted Storage of Batteries. [nickel cadmium batteries

NASA Technical Reports Server (NTRS)

Ritterman, P. F.

1982-01-01

The identification and measurement of hydrogen recombination in sealed nickel-cadium cells makes deep reconditioning on a battery basis safe and feasible. Deep reconditioning improves performance and increases life of nickel-cadium batteries in geosynchronous orbit applications. The hydrogen mechanism and supporting data are presented. Parameter cell design experiments are described which led to the definition of nickel-cadium cells capable of high rate overdischarge without detriment to specific energy. Nickel-cadium calls of identical optimum design were successfully cycled for 7 seasons in simulation of geosynchronous orbit at 75 percent depth-of-discharge with extensive midseason and end-of-season overdischarge at rates varying from C/20 to C/4. Destructive physical analysis and cyclin data indicated no deterioration or the development of dangerous pressures as a result of the cycling with overdischarge.

Predicting Time to Hospital Discharge for Extremely Preterm Infants

PubMed Central

Hintz, Susan R.; Bann, Carla M.; Ambalavanan, Namasivayam; Cotten, C. Michael; Das, Abhik; Higgins, Rosemary D.

2010-01-01

As extremely preterm infant mortality rates have decreased, concerns regarding resource utilization have intensified. Accurate models to predict time to hospital discharge could aid in resource planning, family counseling, and perhaps stimulate quality improvement initiatives. Objectives For infants <27 weeks estimated gestational age (EGA), to develop, validate and compare several models to predict time to hospital discharge based on time-dependent covariates, and based on the presence of 5 key risk factors as predictors. Patients and Methods This was a retrospective analysis of infants <27 weeks EGA, born 7/2002-12/2005 and surviving to discharge from a NICHD Neonatal Research Network site. Time to discharge was modeled as continuous (postmenstrual age at discharge, PMAD), and categorical variables (“Early” and “Late” discharge). Three linear and logistic regression models with time-dependent covariate inclusion were developed (perinatal factors only, perinatal+early neonatal factors, perinatal+early+later factors). Models for Early and Late discharge using the cumulative presence of 5 key risk factors as predictors were also evaluated. Predictive capabilities were compared using coefficient of determination (R2) for linear models, and AUC of ROC curve for logistic models. Results Data from 2254 infants were included. Prediction of PMAD was poor, with only 38% of variation explained by linear models. However, models incorporating later clinical characteristics were more accurate in predicting “Early” or “Late” discharge (full models: AUC 0.76-0.83 vs. perinatal factor models: AUC 0.56-0.69). In simplified key risk factors models, predicted probabilities for Early and Late discharge compared favorably with observed rates. Furthermore, the AUC (0.75-0.77) were similar to those of models including the full factor set. Conclusions Prediction of Early or Late discharge is poor if only perinatal factors are considered, but improves substantially with knowledge of later-occurring morbidities. Prediction using a few key risk factors is comparable to full models, and may offer a clinically applicable strategy. PMID:20008430

Crystal structure and electrochemical properties of rare earth non-stoichiometric AB5-type alloy as negative electrode material in Ni-MH battery

NASA Astrophysics Data System (ADS)

Zhang, Xinbo; Chai, Yujun; Yin, Wenya; Zhao, Minshou

2004-07-01

The La 0.85Mg xNi 4.5Co 0.35Al 0.15 (0.05⩽ x⩽0.35) system compounds have been prepared by arc melting method under Ar atmosphere. X-ray diffraction (XRD) analysis reveals that the as-prepared alloys have different lattice parameters and cell volumes. The electrochemical properties of these alloys have been studied through the charge-discharge recycle testing at different temperatures and discharge currents. It is found that the La 0.85Mg 0.25Ni 4.5Co 0.35Al 0.15 alloy electrode is capable of performing high-rate discharge. Moreover, it has very excellent electrochemical properties as negative electrode materials in Ni-MH battery at low temperature, even at -40°C.

Discharge rating equation and hydraulic characteristics of standard Denil fishways

USGS Publications Warehouse

Odeh, M.

2003-01-01

This paper introduces a new equation to predict discharge capacity in the commonly used Denil fishway using water surface elevation in the upstream reservoir and fishway width and slope as the independent variables. A dimensionless discharge coefficient based only on the physical slope of the fishway is introduced. The discharge equation is based on flow physics, dimensional analysis, and experiments with three full-scale fishways of different sizes. Hydraulic characteristics of flow inside these fishways are discussed. Water velocities decreased by more than 50% and remained relatively unchanged in the fully developed flow downstream of the vena contracta region, near the upstream baffle where fish exit the fishway. Engineers and biologists need to be aware of this fact and ensure that fish can negotiate the vena contracta velocities rather than velocities within the developed flow region only. Discharge capacity was directly proportional to the fishway width and slope. The new equation is a design tool for engineers and field biologists, especially when designing a fishway based on flow availability in conjunction with the swimming capabilities of target fish species.

The influence of negative ions in helium-oxygen barrier discharges: III. Simulation of laser photodetachment and comparison with experiment

NASA Astrophysics Data System (ADS)

Nemschokmichal, Sebastian; Tschiersch, Robert; Meichsner, Jürgen

2017-11-01

The laser photodetachment experiment in a diffuse helium-oxygen barrier discharge is evaluated by a 1D fluid simulation. As in the experiment, the simulated discharge operates in helium with 400 {ppm} oxygen admixture at 500 {mbar} inside a discharge gap of 3 {mm}. The laser photodetachment is included by the interaction of negative ions with a temporally and spatially dependent photon flux. The simulation with the usually applied set of reactions and rate coefficients provides a much lower negative ion density than needed to explain the impact on the discharge characteristics in the experiment. Further processes for an enhanced negative ion formation and their capabilities of reproducing the experimental results are discussed. These further processes are additional attachment processes in the volume and the negative ion formation at the negatively charged dielectric. Both approaches are able to reproduce the measured laser photodetachment effect partially, but the best agreement with the experimental results is achieved with the formation of negative ions at the negatively charged dielectric.

Hyper-dendritic nanoporous zinc foam anodes

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

Chamoun, Mylad; Hertzberg, Benjamin J.; Gupta, Tanya

The low cost, significant reducing potential, and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1 - 96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrastmore » to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~ 88% at full depth-of-discharge at various rates indicating a superb rate-capability. The rechargeability of Zn⁰/Zn²⁺ showed significant capacity retention over 100 cycles at a 40% depth-of-discharge to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge-discharge cycling and presented superior performance compared to bulk zinc electrodes.« less

Hyper-dendritic nanoporous zinc foam anodes

DOE PAGES

Chamoun, Mylad; Hertzberg, Benjamin J.; Gupta, Tanya; ...

2015-04-24

The low cost, significant reducing potential, and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1 - 96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrastmore » to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~ 88% at full depth-of-discharge at various rates indicating a superb rate-capability. The rechargeability of Zn⁰/Zn²⁺ showed significant capacity retention over 100 cycles at a 40% depth-of-discharge to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge-discharge cycling and presented superior performance compared to bulk zinc electrodes.« less

Fabrication and testing of negative limited sealed nickel-cadmium cells

NASA Technical Reports Server (NTRS)

Gordy, D. J.

1975-01-01

A number of 20 Ah and 3 Ah negative limited nickel-cadmium cells were fabricated and assembled in hermetically sealed stainless steel containers. The cells exhibit a large voltage rise signal, in excess of 250 mA, at the end of each charge period. They also exhibit lower self discharge rates than conventional sealed nickel-cadmium cells and do not require overcharge. The cells are capable of operating at charge and discharge rates up to 5C and can deliver at least 1000 cycles on a 30 minute regime at 25% DOD. A small amount of gassing occurs, but is not deemed critical or detrimental in view of the facts that, (1) operating pressures are in the range of 7 to 20 psig and (2) the cells are operated in the flooded condition so therefore contain little internal void volume. The cells were found to exhibit somewhat higher capacity loss rates during cycling than conventional sealed nickel-cadmium batteries.

Consistency assessment of rating curve data in various locations using Bidirectional Reach (BReach)

NASA Astrophysics Data System (ADS)

Van Eerdenbrugh, Katrien; Van Hoey, Stijn; Coxon, Gemma; Freer, Jim; Verhoest, Niko E. C.

2017-10-01

When estimating discharges through rating curves, temporal data consistency is a critical issue. In this research, consistency in stage-discharge data is investigated using a methodology called Bidirectional Reach (BReach), which departs from a (in operational hydrology) commonly used definition of consistency. A period is considered to be consistent if no consecutive and systematic deviations from a current situation occur that exceed observational uncertainty. Therefore, the capability of a rating curve model to describe a subset of the (chronologically sorted) data is assessed in each observation by indicating the outermost data points for which the rating curve model behaves satisfactorily. These points are called the maximum left or right reach, depending on the direction of the investigation. This temporal reach should not be confused with a spatial reach (indicating a part of a river). Changes in these reaches throughout the data series indicate possible changes in data consistency and if not resolved could introduce additional errors and biases. In this research, various measurement stations in the UK, New Zealand and Belgium are selected based on their significant historical ratings information and their specific characteristics related to data consistency. For each country, regional information is maximally used to estimate observational uncertainty. Based on this uncertainty, a BReach analysis is performed and, subsequently, results are validated against available knowledge about the history and behavior of the site. For all investigated cases, the methodology provides results that appear to be consistent with this knowledge of historical changes and thus facilitates a reliable assessment of (in)consistent periods in stage-discharge measurements. This assessment is not only useful for the analysis and determination of discharge time series, but also to enhance applications based on these data (e.g., by informing hydrological and hydraulic model evaluation design about consistent time periods to analyze).

High-rate in-plane micro-supercapacitors scribed onto photo paper using in situ femtolaser-reduced graphene oxide/Au nanoparticle microelectrodes

DOE PAGES

Li, Ruozhou; Peng, Rui; Tumuluri, Uma; ...

2016-02-11

Direct laser-reduction of graphene oxide (GO), as a lithography-free approach, has been proven effective in manufacturing in-plane micro-supercapacitors (MSCs) with fast ion diffusion. However, the power density and the charge/discharge rate are still limited by the relatively low conductivity of electrodes. Here, we report a facile approach by exploiting femtolaser in situ reduction of the hydrated GO and chloroauric acid (HAuCl 4) nanocomposite simultaneously, which incorporates both the patterning of rGO electrodes and the fabrication of Au current collectors in a single step. These flexible MSCs boast achievements of one-hundred fold increase in electrode conductivities of up to 1.1 ×more » 10 6 S m –1, which provide superior rate capability (50% for the charging rate increase from 0.1 V s –1 to 100 V s –1), sufficiently high frequency responses (362 Hz, 2.76 ms time constant), and large specific capacitances of 0.77 mF cm –2 (17.2 F cm –3 for volumetric capacitance) at 1 V s –1, and 0.46 mF cm –2 (10.2 F cm –3) at 100 V s –1. The use of photo paper substrates enables the flexibility of this fabrication protocol. Moreover, proof-of-concept 3D MSCs are demonstrated with enhanced areal capacitance (up to 3.84 mF cm –2 at 1 V s –1) while keeping high rate capabilities. As a result, this prototype of all solid-state MSCs demonstrates the broad range of potentials of thin-film based energy storage device applications for flexible, portable, and wearable electronic devices that require a fast charge/discharge rate and high power density.« less

High-rate in-plane micro-supercapacitors scribed onto photo paper using in situ femtolaser-reduced graphene oxide/Au nanoparticle microelectrodes

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

Li, Ruozhou; Peng, Rui; Tumuluri, Uma

Direct laser-reduction of graphene oxide (GO), as a lithography-free approach, has been proven effective in manufacturing in-plane micro-supercapacitors (MSCs) with fast ion diffusion. However, the power density and the charge/discharge rate are still limited by the relatively low conductivity of electrodes. Here, we report a facile approach by exploiting femtolaser in situ reduction of the hydrated GO and chloroauric acid (HAuCl 4) nanocomposite simultaneously, which incorporates both the patterning of rGO electrodes and the fabrication of Au current collectors in a single step. These flexible MSCs boast achievements of one-hundred fold increase in electrode conductivities of up to 1.1 ×more » 10 6 S m –1, which provide superior rate capability (50% for the charging rate increase from 0.1 V s –1 to 100 V s –1), sufficiently high frequency responses (362 Hz, 2.76 ms time constant), and large specific capacitances of 0.77 mF cm –2 (17.2 F cm –3 for volumetric capacitance) at 1 V s –1, and 0.46 mF cm –2 (10.2 F cm –3) at 100 V s –1. The use of photo paper substrates enables the flexibility of this fabrication protocol. Moreover, proof-of-concept 3D MSCs are demonstrated with enhanced areal capacitance (up to 3.84 mF cm –2 at 1 V s –1) while keeping high rate capabilities. As a result, this prototype of all solid-state MSCs demonstrates the broad range of potentials of thin-film based energy storage device applications for flexible, portable, and wearable electronic devices that require a fast charge/discharge rate and high power density.« less

Reducing falls after hospital discharge: a protocol for a randomised controlled trial evaluating an individualised multimodal falls education programme for older adults.

PubMed

Hill, Anne-Marie; Etherton-Beer, Christopher; McPhail, Steven M; Morris, Meg E; Flicker, Leon; Shorr, Ronald; Bulsara, Max; Lee, Den-Ching; Francis-Coad, Jacqueline; Waldron, Nicholas; Boudville, Amanda; Haines, Terry

2017-02-02

Older adults frequently fall after discharge from hospital. Older people may have low self-perceived risk of falls and poor knowledge about falls prevention. The primary aim of the study is to evaluate the effect of providing tailored falls prevention education in addition to usual care on falls rates in older people after discharge from hospital compared to providing a social intervention in addition to usual care. The 'Back to My Best' study is a multisite, single blind, parallel-group randomised controlled trial with blinded outcome assessment and intention-to-treat analysis, adhering to CONSORT guidelines. Patients (n=390) (aged 60 years or older; score more than 7/10 on the Abbreviated Mental Test Score; discharged to community settings) from aged care rehabilitation wards in three hospitals will be recruited and randomly assigned to one of two groups. Participants allocated to the control group shall receive usual care plus a social visit. Participants allocated to the experimental group shall receive usual care and a falls prevention programme incorporating a video, workbook and individualised follow-up from an expert health professional to foster capability and motivation to engage in falls prevention strategies. The primary outcome is falls rates in the first 6 months after discharge, analysed using negative binomial regression with adjustment for participant's length of observation in the study. Secondary outcomes are injurious falls rates, the proportion of people who become fallers, functional status and health-related quality of life. Healthcare resource use will be captured from four sources for 6 months after discharge. The study is powered to detect a 30% relative reduction in the rate of falls (negative binomial incidence ratio 0.70) for a control rate of 0.80 falls per person over 6 months. Results will be presented in peer-reviewed journals and at conferences worldwide. This study is approved by hospital and university Human Research Ethics Committees. ACTRN12615000784516. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Reducing falls after hospital discharge: a protocol for a randomised controlled trial evaluating an individualised multimodal falls education programme for older adults

PubMed Central

Hill, Anne-Marie; Etherton-Beer, Christopher; McPhail, Steven M; Morris, Meg E; Flicker, Leon; Bulsara, Max; Lee, Den-Ching; Francis-Coad, Jacqueline; Waldron, Nicholas; Boudville, Amanda; Haines, Terry

2017-01-01

Introduction Older adults frequently fall after discharge from hospital. Older people may have low self-perceived risk of falls and poor knowledge about falls prevention. The primary aim of the study is to evaluate the effect of providing tailored falls prevention education in addition to usual care on falls rates in older people after discharge from hospital compared to providing a social intervention in addition to usual care. Methods and analyses The ‘Back to My Best’ study is a multisite, single blind, parallel-group randomised controlled trial with blinded outcome assessment and intention-to-treat analysis, adhering to CONSORT guidelines. Patients (n=390) (aged 60 years or older; score more than 7/10 on the Abbreviated Mental Test Score; discharged to community settings) from aged care rehabilitation wards in three hospitals will be recruited and randomly assigned to one of two groups. Participants allocated to the control group shall receive usual care plus a social visit. Participants allocated to the experimental group shall receive usual care and a falls prevention programme incorporating a video, workbook and individualised follow-up from an expert health professional to foster capability and motivation to engage in falls prevention strategies. The primary outcome is falls rates in the first 6 months after discharge, analysed using negative binomial regression with adjustment for participant's length of observation in the study. Secondary outcomes are injurious falls rates, the proportion of people who become fallers, functional status and health-related quality of life. Healthcare resource use will be captured from four sources for 6 months after discharge. The study is powered to detect a 30% relative reduction in the rate of falls (negative binomial incidence ratio 0.70) for a control rate of 0.80 falls per person over 6 months. Ethics and dissemination Results will be presented in peer-reviewed journals and at conferences worldwide. This study is approved by hospital and university Human Research Ethics Committees. Trial registration number ACTRN12615000784516. PMID:28153933

High-performance lithium-ion battery and symmetric supercapacitors based on FeCo₂O₄ nanoflakes electrodes.

PubMed

Mohamed, Saad Gomaa; Chen, Chih-Jung; Chen, Chih Kai; Hu, Shu-Fen; Liu, Ru-Shi

2014-12-24

A successive preparation of FeCo2O4 nanoflakes arrays on nickel foam substrates is achieved by a simple hydrothermal synthesis method. After 170 cycles, a high capacity of 905 mAh g(-1) at 200 mA g(-1) current density and very good rate capabilities are obtained for lithium-ion battery because of the 2D porous structures of the nanoflakes arrays. The distinctive structural features provide the battery with excellent electrochemical performance. The symmetric supercapacitor on nonaqueous electrolyte demonstrates high specific capacitance of 433 F g(-1) at 0.1 A g(-1) and 16.7 F g(-1) at high scan rate of 5 V s(-1) and excellent cyclic performance of 2500 cycles of charge-discharge cycling at 2 A g(-1) current density, revealing excellent long-term cyclability of the electrode even under rapid charge-discharge conditions.

O3-type layered transition metal oxide Na(NiCoFeTi) 1/4O 2 as a high rate and long cycle life cathode material for sodium ion batteries

DOE PAGES

Yue, Ji -Li; Yang, Xiao -Qing; Zhou, Yong -Ning; ...

2015-10-09

High rate capability and long cycle life are challenging goals for the development of room temperature sodium-ion batteries. Here we report a new single phase quaternary O3-type layer-structured transition metal oxide Na(NiCoFeTi) 1/4O 2 synthesized by a simple solid-state reaction as a new cathode material for sodium-ion batteries. It can deliver a reversible capacity of 90.6 mA h g –1 at a rate as high as 20C. At 5C, 75.0% of the initial specific capacity can be retained after 400 cycles with a capacity-decay rate of 0.07% per cycle, demonstrating a superior long-term cyclability at high current density. X-ray diffractionmore » and absorption characterization revealed reversible phase transformations and electronic structural changes during the Na + deintercalation/intercalation process. Ni, Co and Fe ions contribute to charge compensation during charge and discharge. Although Ti ions do not contribute to the charge transfer, they play a very important role in stabilizing the structure during charge and discharge by suppressing the Fe migration. Additionally, Ti substitution can also smooth the charge–discharge plateaus effectively, which provides a potential advantage for the commercialization of this material for room temperature sodium-ion batteries.« less

Hierarchical LiMn2O4 Hollow Cubes with Exposed {111} Planes as High-Power Cathodes for Lithium-Ion Batteries.

PubMed

Wu, Yu; Cao, Chuanbao; Zhang, Junting; Wang, Lin; Ma, Xilan; Xu, Xingyan

2016-08-03

Hierarchical LiMn2O4 hollow cubes with exposed {111} planes have been synthesized using cube-shaped MnCO3 precursors, which are fabricated through a facile co-precipitation reaction. Without surface modification, the as-prepared LiMn2O4 exhibits excellent cyclability and superior rate capability. Surprisingly, even over 70% of primal discharge capacity can be maintained for up to 1000 cycles at 50 C, and with only about 72 s of discharge time the as-prepared materials can deliver initial discharge capacity of 96.5 mA h g(-1). What is more, the materials have 98.4% and 90.7% capacity retentions for up to 100 cycles at 5 C under the temperatures of 25 and 60 °C, respectively. The superior electrochemical performance can be attributed to the unique hierarchical and interior hollow structure, exposed {111} planes, and high-quality crystallinity.

Porous, Hyper-cross-linked, Three-Dimensional Polymer as Stable, High Rate Capability Electrode for Lithium-Ion Battery.

PubMed

Mukherjee, Debdyuti; Gowda Y K, Guruprasada; Makri Nimbegondi Kotresh, Harish; Sampath, S

2017-06-14

Organic materials containing active carbonyl groups have attracted considerable attention as electrodes in Li-ion batteries due to their reversible redox activity, ability to retain capacity, and, in addition, their ecofriendly nature. Introduction of porosity will help accommodate as well as store small ions and molecules reversibly. In the present work, we introduce a mesoporous triptycene-related, rigid network polymer with high specific surface area as an electrode material for rechargeable Li-ion battery. The designed polymer with a three-dimensional (3D), rigid porous network allows free movement of ions/electrolyte as well as helps in interacting with the active anhydride moieties (containing two carbonyl groups). Considerable intake of Li + ions giving rise to very high specific capacity of 1100 mA h g -1 at a discharge current of 50 mA g -1 and ∼120 mA h g -1 at a high discharge current of 3 A g -1 are observed with excellent cyclability up to 1000 cycles. This remarkable rate capability, which is one of the highest among the reported organic porous polymers to date, makes the triptycene-related rigid 3D network a very good choice for Li-ion batteries and opens up a new method to design polymer-based electrode materials for metal-ion battery technology.

Porous lithium nickel cobalt manganese oxide hierarchical nanosheets as high rate capability cathodes for lithium ion batteries

NASA Astrophysics Data System (ADS)

Li, Jili; Wang, Xiaofeng; Zhao, Junwei; Chen, Jian; Jia, Tiekun; Cao, Chuanbao

2016-03-01

Novel 2D LiNi1/3Co1/3Mn1/3O2 hierarchical nanosheets are successfully synthesized through a simple sol-gel strategy with ethanol dispersion of carbon nanotubes as addictive. The nanosheets with thickness of ∼100 nm appear porous and are formed by 100 nm nanoparticles. As cathode for lithium ion battery, the 2D porous hierarchical nanosheets demonstrate high specific capacity of 137.7 mAh g-1 at 20C (1C = 200 mA g-1), which is much higher than those of its counterparts. The high capacity can be still maintained during 100 charge/discharge cycles and the capacity retention is up to 90.1%. The excellent rate capability and cyclability may be attributed to the distinct 2D porous hierarchical structure.

New approach to calibrating bed load samplers

USGS Publications Warehouse

Hubbell, D.W.; Stevens, H.H.; Skinner, J.V.; Beverage, J.P.

1985-01-01

Cyclic variations in bed load discharge at a point, which are an inherent part of the process of bed load movement, complicate calibration of bed load samplers and preclude the use of average rates to define sampling efficiencies. Calibration curves, rather than efficiencies, are derived by two independent methods using data collected with prototype versions of the Helley‐Smith sampler in a large calibration facility capable of continuously measuring transport rates across a 9 ft (2.7 m) width. Results from both methods agree. Composite calibration curves, based on matching probability distribution functions of samples and measured rates from different hydraulic conditions (runs), are obtained for six different versions of the sampler. Sampled rates corrected by the calibration curves agree with measured rates for individual runs.

Improved Cycling Stability and Fast Charge-Discharge Performance of Cobalt-Free Lithium-Rich Oxides by Magnesium-Doping.

PubMed

Yi, Ting-Feng; Li, Yan-Mei; Yang, Shuang-Yuan; Zhu, Yan-Rong; Xie, Ying

2016-11-30

Layered Li-rich, Co-free, and Mn-based cathode material, Li 1.17 Ni 0.25-x Mn 0.58 Mg x O 2 (0 ≤ x ≤ 0.05), was successfully synthesized by a coprecipitation method. All prepared samples have typical Li-rich layered structure, and Mg has been doped in the Li 1.17 Ni 0.25 Mn 0.58 O 2 material successfully and homogeneously. The morphology and the grain size of all material are not changed by Mg doping. All materials have a estimated size of about 200 nm with a narrow particle size distribution. The electrochemical property results show that Li 1.17 Ni 0.25-x Mn 0.58 Mg x O 2 (x = 0.01 and 0.02) electrodes exhibit higher rate capability than that of the pristine one. Li 1.17 Ni 0.25-x Mn 0.58 Mg x O 2 (x = 0.02) indicates the largest reversible capacity of 148.3 mAh g -1 and best cycling stability (capacity retention of 95.1%) after 100 cycles at 2C charge-discharge rate. Li 1.17 Ni 0.25-x Mn 0.58 Mg x O 2 (x = 0.02) also shows the largest discharge capacity of 149.2 mAh g -1 discharged at 1C rate at elevated temperature (55 °C) after 50 cycles. The improved electrochemical performances may be attributed to the decreased polarization, reduced charge transfer resistance, enhanced the reversibility of Li + ion insertion/extraction, and increased lithium ion diffusion coefficient. This promising result gives a new understanding for designing the structure and improving the electrochemical performance of Li-rich cathode materials for the next-generation lithium-ion battery with high rate cycling performance.

Post-Test Inspection of NASA's Evolutionary Xenon Thruster Long-Duration Test Hardware: Discharge Chamber

NASA Technical Reports Server (NTRS)

Shastry, Rohit; Soulas, George C.

2016-01-01

The NEXT Long-Duration Test is part of a comprehensive thruster service life assessment intended to demonstrate overall throughput capability, validate service life models, quantify wear rates as a function of time and operating condition, and identify any unknown life-limiting mechanisms. The test was voluntarily terminated in February 2014 after demonstrating 51,184 hours of high-voltage operation, 918 kg of propellant throughput, and 35.5 MN-s of total impulse. The post-test inspection of the thruster hardware began shortly afterwards with a combination of non-destructive and destructive analysis techniques, and is presently nearing completion. This paper presents relevant results of the post-test inspection for the discharge chamber as well as other miscellaneous components such as the high-voltage propellant isolators and electrical cabling. Comparison of magnetic field measurements taken during pretest and post-test inspections indicate that the field strength did not degrade, consistent with performance data obtained during the test. Inspection of discharge chamber mesh samples show a deposition coating primarily composed of grid material that is approximately 15 micrometers in thickness. This thickness is well within the retention capability of the mesh and is therefore not expected to present any issues. Approximately 3.1 grams of deposition flakes were found at the bottom of the discharge chamber, composed primarily of grid material and carbon. Calculated size histograms of these flakes indicate that 99% have a maximum dimension of 200 micrometers or smaller, which is significantly less than the ion optics grid gap. Larger flakes that are capable of causing a grid-to-grid short will be analyzed to determine if their formation will occur in flight or is a facility effect. The high-voltage propellant isolators as well as numerous other electrical insulators were inspected and no evidence of arcing or any other issues were found.

Reduced Graphene Oxide-Wrapped FeS2 Composite as Anode for High-Performance Sodium-Ion Batteries

NASA Astrophysics Data System (ADS)

Wang, Qinghong; Guo, Can; Zhu, Yuxuan; He, Jiapeng; Wang, Hongqiang

2018-06-01

Iron disulfide is considered to be a potential anode material for sodium-ion batteries due to its high theoretical capacity. However, its applications are seriously limited by the weak conductivity and large volume change, which results in low reversible capacity and poor cycling stability. Herein, reduced graphene oxide-wrapped FeS2 (FeS2/rGO) composite was fabricated to achieve excellent electrochemical performance via a facile two-step method. The introduction of rGO effectively improved the conductivity, BET surface area, and structural stability of the FeS2 active material, thus endowing it with high specific capacity, good rate capability, as well as excellent cycling stability. Electrochemical measurements show that the FeS2/rGO composite had a high initial discharge capacity of 1263.2 mAh g-1 at 100 mA g-1 and a high discharge capacity of 344 mAh g-1 at 10 A g-1, demonstrating superior rate performance. After 100 cycles at 100 mA g-1, the discharge capacity remained at 609.5 mAh g-1, indicating the excellent cycling stability of the FeS2/rGO electrode.

Pulsed dielectric barrier discharge for Bacillus subtilis inactivation in water

NASA Astrophysics Data System (ADS)

Hernández-Arias, A. N.; Rodríguez-Méndez, B. G.; López-Callejas, R.; Valencia-Alvarado, R.; Mercado-Cabrera, A.; Peña-Eguiluz, R.; Barocio, S. R.; Muñoz-Castro, A. E.; de la Piedad Beneitez, A.

2012-06-01

The inactivation of Bacillus subtilis bacteria in water has been experimentally studied by means of a pulsed dielectric barrier discharge (PDBD) in a coaxial reactor endowed with an alumina dielectric. The plasma source is capable of operating at atmospheric pressure with gas, water or hybrid gas-liquid media at adjustable 25 kV pulses, 30 μs long and at a 500 Hz frequency. In order to evaluate the inactivation efficiency of the system, a set of experiments were designed on the basis of oxygen flow control. The initial data have showed a significant bacterial rate reduction of 103-107 CFU/mL. Additional results proved that applying an oxygen flow for a few seconds during the PDBD treatment inactivates the Bacillus subtilis population with 99.99% effectiveness. As a reference, without gas flow but with the same exposure times, this percentage is reduced to ~90%. The analysis of the relationship between inactivation rate and chemical species in the discharge has been carried out using optical emission spectroscopy as to identifying the main reactive species. Reactive oxygen species such as atomic oxygen and ozone tuned out to be the dominant germicidal species. Some proposed inactivation mechanisms of this technique are discussed.

Design of a fast computer-based partial discharge diagnostic system

NASA Technical Reports Server (NTRS)

Oliva, Jose R.; Karady, G. G.; Domitz, Stan

1991-01-01

Partial discharges cause progressive deterioration of insulating materials working in high voltage conditions and may lead ultimately to insulator failure. Experimental findings indicate that deterioration increases with the number of discharges and is consequently proportional to the magnitude and frequency of the applied voltage. In order to obtain a better understanding of the mechanisms of deterioration produced by partial discharges, instrumentation capable of individual pulse resolution is required. A new computer-based partial discharge detection system was designed and constructed to conduct long duration tests on sample capacitors. This system is capable of recording large number of pulses without dead time and producing valuable information related to amplitude, polarity, and charge content of the discharges. The operation of the system is automatic and no human supervision is required during the testing stage. Ceramic capacitors were tested at high voltage in long duration tests. The obtained results indicated that the charge content of partial discharges shift towards high levels of charge as the level of deterioration in the capacitor increases.

Post-Test Inspection of NASA's Evolutionary Xenon Thruster Long-Duration Test Hardware: Discharge and Neutralizer Cathodes

NASA Technical Reports Server (NTRS)

Shastry, Rohit; Soulas, George C.

2016-01-01

The NEXT Long-Duration Test is part of a comprehensive thruster service life assessment intended to demonstrate overall throughput capability, validate service life models, quantify wear rates as a function of time and operating condition, and identify any unknown life-limiting mechanisms. The test was voluntarily terminated in April 2014 after demonstrating 51,184 hours of high-voltage operation, 918 kg of propellant throughput, and 35.5 MN-s of total impulse. The post-test inspection of the thruster hardware began shortly afterwards with a combination of non-destructive and destructive analysis techniques, and is presently nearing completion. This presentation presents relevant results of the post-test inspection for both discharge and neutralizer cathodes.

Nanodisperse transition metal electrodes (NTME) for electrochemical cells

DOEpatents

Striebel, Kathryn A.; Wen, Shi-Jie

2000-01-01

Disclosed are transition metal electrodes for electrochemical cells using gel-state and solid-state polymers. The electrodes are suitable for use in primary and secondary cells. The electrodes (either negative electrode or positive electrode) are characterized by uniform dispersion of the transition metal at the nanoscale in the polymer. The transition metal moiety is structurally amorphous, so no capacity fade should occur due to lattice expansion/contraction mechanisms. The small grain size, amorphous structure and homogeneous distribution provide improved charge/discharge cycling performance, and a higher initial discharge rate capability. The cells can be cycled at high current densities, limited only by the electrolyte conductivity. A method of making the electrodes (positive and negative), and their usage in electrochemical cells are disclosed.

Three-Dimensional Honeycomb-Structural LiAlO2-Modified LiMnPO4 Composite with Superior High Rate Capability as Li-Ion Battery Cathodes.

PubMed

Li, Junzhe; Luo, Shaohua; Ding, Xueyong; Wang, Qing; He, Ping

2018-04-04

In the efforts toward the rapidly increasing demands for high-power application, cathode materials with three-dimensional (3D) architectures have been proposed. Here, we report the construction of the 3D LiAlO 2 -LiMnPO 4 /C cathode materials for lithium-ion batteries in an innovation way. The as-prepared 3D active materials LiMnPO 4 /C and the honeycomb-like Li-ion conductor LiAlO 2 framework are used as working electrode directly without additional usage of polymeric binder. The electrochemical performance has been improved significantly due to the special designed core-shell architectures of LiMnPO 4 /C@LiAlO 2 . The 3D binder-free electrode exhibits high rate capability as well as superior cycling stability with a capability of ∼105 mAh g -1 and 98.4% capacity retention after 100 cycles at a high discharge rate of 10 C. Such synthesis method adopted in our work can be further extended to other promising candidates and would also inspire new avenues of development of 3D materials for lithium-ion batteries.

Payments for acute myocardial infarction episodes-of-care initiated at hospitals with and without interventional capabilities.

PubMed

Ben-Josef, Gal; Ott, Lesli S; Spivack, Steven B; Wang, Changqin; Ross, Joseph S; Shah, Sachin J; Curtis, Jeptha P; Kim, Nancy; Krumholz, Harlan M; Bernheim, Susannah M

2014-11-01

It is unknown whether hospitals with percutaneous coronary intervention (PCI) capability provide costlier care than hospitals without PCI capability for patients with acute myocardial infarction. The growing number of PCI hospitals and higher rate of PCI use may result in higher costs for episodes-of-care initiated at PCI hospitals. However, higher rates of transfers and postacute care procedures may result in higher costs for episodes-of-care initiated at non-PCI hospitals. We identified all 2008 acute myocardial infarction admissions among Medicare fee-for-service beneficiaries by principal discharge diagnosis and classified hospitals as PCI- or non-PCI-capable on the basis of hospitals' 2007 PCI performance. We added all payments from admission through 30 days postadmission, including payments to hospitals other than the admitting hospital. We calculated and compared risk-standardized payment for PCI and non-PCI hospitals using 2-level hierarchical generalized linear models, adjusting for patient demographics and clinical characteristics. PCI hospitals had a higher mean 30-day risk-standardized payment than non-PCI hospitals (PCI, $20 340; non-PCI, $19 713; P<0.001). Patients presenting to PCI hospitals had higher PCI rates (39.2% versus 13.2%; P<0.001) and higher coronary artery bypass graft rates (9.5% versus 4.4%; P<0.001) during index admissions, lower transfer rates (2.2% versus 25.4%; P<0.001), and lower revascularization rates within 30 days (0.15% versus 0.27%; P<0.0001) than those presenting to non-PCI hospitals. Despite higher PCI and coronary artery bypass graft rates for Medicare patients initially presenting to PCI hospitals, PCI hospitals were only $627 costlier than non-PCI hospitals for the treatment of patients with acute myocardial infarction in 2008. © 2014 American Heart Association, Inc.

Microstructure and pseudocapacitive properties of electrodes constructed of oriented NiO-TiO2 nanotube arrays.

PubMed

Kim, Jae-Hun; Zhu, Kai; Yan, Yanfa; Perkins, Craig L; Frank, Arthur J

2010-10-13

We report on the synthesis and electrochemical properties of oriented NiO-TiO(2) nanotube (NT) arrays as electrodes for supercapacitors. The morphology of the films prepared by electrochemically anodizing Ni-Ti alloy foils was characterized by scanning and transmission electron microscopies, X-ray diffraction, and photoelectron spectroscopies. The morphology, crystal structure, and composition of the NT films were found to depend on the preparation conditions (anodization voltage and postgrowth annealing temperature). Annealing the as-grown NT arrays to a temperature of 600 °C transformed them from an amorphous phase to a mixture of crystalline rock salt NiO and rutile TiO(2). Changes in the morphology and crystal structure strongly influenced the electrochemical properties of the NT electrodes. Electrodes composed of NT films annealed at 600 °C displayed pseudocapacitor (redox-capacitor) behavior, including rapid charge/discharge kinetics and stable long-term cycling performance. At similar film thicknesses and surface areas, the NT-based electrodes showed a higher rate capability than the randomly packed nanoparticle-based electrodes. Even at the highest scan rate (500 mV/s), the capacitance of the NT electrodes was not much smaller (within 12%) than the capacitance measured at the slowest scan rate (5 mV/s). The faster charge/discharge kinetics of NT electrodes at high scan rates is attributed to the more ordered NT film architecture, which is expected to facilitate electron and ion transport during the charge-discharge reactions.

A high power lithium thionyl chloride battery for space applications

NASA Technical Reports Server (NTRS)

Shah, Pinakin M.

1993-01-01

A high power, 28 V, 330 A h, active lithium thionyl chloride battery has been developed for use as main and payload power sources on an expendable launch vehicle. Nine prismatic cells, along with the required electrical components and a built-in heater system, are efficiently packaged resulting in significant weight savings over presently used silver-zinc batteries. The high rate capability is achieved by designing the cells with a large electrochemical surface area and impregnating an electrocatalyst, polymeric phthalocyanine, into the carbon cathodes. Passivation effects are reduced with the addition of sulfur dioxide into the thionyl chloride electrolyte solution. The results of conducting a detailed thermal analysis are utilized to establish the heater design parameters and the thermal insulation requirements of the battery. An analysis of cell internal pressure and vent characteristics clearly illustrates the margins of safety under different operating conditions. Performance of fresh cells is discussed using polarization scan and discharge data at different rates and temperatures. Self-discharge rate is estimated based upon test results on cells after storage. Results of testing a complete prototype battery are described.

Pulsed high voltage electric discharge disinfection of microbially contaminated liquids.

PubMed

Anpilov, A M; Barkhudarov, E M; Christofi, N; Kop'ev, V A; Kossyi, I A; Taktakishvili, M I; Zadiraka, Y

2002-01-01

To examine the use of a novel multielectrode slipping surface discharge (SSD) treatment system, capable of pulsed plasma discharge directly in water, in killing micro-organisms. Potable water containing Escherichia coli and somatic coliphages was treated with pulsed electric discharges generated by the SSD. The SSD system was highly efficient in the microbial disinfection of water with a low energy utilization (eta approximately 10-4 kW h l-1). The SSD treatment was effective in the destruction of E. coli and its coliphages through the generation of u.v. radiation, ozone and free radicals. The non-thermal treatment method can be used for the eradication of micro-organisms in a range of contaminated liquids, including milk, negating the use of pasteurization. The method utilizes multipoint electric discharges capable of treating large volumes of liquid under static and flowing regimes.

Ultra-high power capabilities in amorphous FePO4 thin films

NASA Astrophysics Data System (ADS)

Gandrud, Knut B.; Nilsen, Ola; Fjellvåg, Helmer

2016-02-01

Record breaking electrochemical properties of FePO4 have been found through investigation of the thickness dependent electrochemical properties of amorphous thin film electrodes. Atomic layer deposition was used for production of thin films of amorphous FePO4 with highly accurate thickness and topography. Electrochemical characterization of these thin film electrodes revealed that the thinner electrodes behave in a pseudocapacitive manner even at high rates of Li+ de/intercalation, which enabled specific powers above 1 MW kg-1 FePO4 to be obtained with minimal capacity loss. In addition, a self-enhancing kinetic effect was observed during cycling enabling more than 10,000 cycles at current rates approaching that of a supercapacitor (11s charge/discharge). The current findings may open for construction of ultra-high power battery electrodes that combines the energy density of batteries with the power capabilities of supercapacitors.

An improved high-performance lithium-air battery.

PubMed

Jung, Hun-Gi; Hassoun, Jusef; Park, Jin-Bum; Sun, Yang-Kook; Scrosati, Bruno

2012-06-10

Although dominating the consumer electronics markets as the power source of choice for popular portable devices, the common lithium battery is not yet suited for use in sustainable electrified road transport. The development of advanced, higher-energy lithium batteries is essential in the rapid establishment of the electric car market. Owing to its exceptionally high energy potentiality, the lithium-air battery is a very appealing candidate for fulfilling this role. However, the performance of such batteries has been limited to only a few charge-discharge cycles with low rate capability. Here, by choosing a suitable stable electrolyte and appropriate cell design, we demonstrate a lithium-air battery capable of operating over many cycles with capacity and rate values as high as 5,000 mAh g(carbon)(-1) and 3 A g(carbon)(-1), respectively. For this battery we estimate an energy density value that is much higher than those offered by the currently available lithium-ion battery technology.

Uncovering a facile large-scale synthesis of LiNi1/3Co1/3Mn1/3O2 nanoflowers for high power lithium-ion batteries

NASA Astrophysics Data System (ADS)

Hua, Wei-Bo; Guo, Xiao-Dong; Zheng, Zhuo; Wang, Yan-Jie; Zhong, Ben-He; Fang, Baizeng; Wang, Jia-Zhao; Chou, Shu-Lei; Liu, Heng

2015-02-01

Developing advanced electrode materials that deliver high energy at ultra-fast charge and discharge rates are very crucial to meet an increasing large-scale market demand for high power lithium ion batteries (LIBs). A three-dimensional (3D) nanoflower structure is successfully developed in the large-scale synthesis of LiNi1/3Co1/3Mn1/3O2 material for the first time. The fast co-precipitation is the key technique to prepare the nanoflower structure in our method. After heat treatment, the obtained LiNi1/3Co1/3Mn1/3O2 nanoflowers (NL333) pronouncedly present a pristine flower-like nano-architecture and provide fast pathways for the transport of Li-ions and electrons. As a cathode material in a LIB, the prepared NL333 electrode demonstrates an outstanding high-rate capability. Particularly, in a narrow voltage range of 2.7-4.3 V, the discharge capacity at an ultra-fast charge-discharge rate (20C) is up to 126 mAh g-1, which reaches 78% of that at 0.2C, and is much higher than that (i.e., 44.17%) of the traditional bulk LiNi1/3Co1/3Mn1/3O2.

Structural and electrochemical properties of Gd-doped Li4Ti5O12 as anode material with improved rate capability for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Qianyu; Verde, Michael G.; Seo, Joon Kyo; Li, Xi; Meng, Y. Shirley

2015-04-01

Pristine and Gd-doped Li4Ti5O12 (LTO) in the form of Li4-x/3Ti5-2x/3GdxO12 (x = 0.05, 0.10 and 0.15) were prepared by a simple solid-state reaction in air. The structural and electrochemical properties of the as-prepared powders were characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). XRD revealed that only a small amount of the dopant can enter the lattice structure of LTO; excessive addition beyond x = 0.10 resulted in a discrete Gd2O3 impurity phase. The Gd doping did not change the spinel structure and electrochemical reaction process of LTO. The average particle size of as-prepared samples ranged between 0.5 and 1.5 μm. The Gd-doped materials showed much improved rate capability and specific capacity compared with undoped LTO. In particular, Li4-x/3Ti5-2x/3GdxO12 (x = 0.5) exhibited the best rate capability and cycling stability among all samples. Beyond this doping level, however, Gd2O3 impurity phase in the LTO led to adverse electrochemical performance. The rate capability of the anode material made from the modified powder is significantly improved when discharged at high current rates due to the reduced charge transfer resistance and fast lithium insertion/extraction kinetics.

FAST TRACK COMMUNICATION: Deposition of amino-rich thin films by RF magnetron sputtering of nylon

NASA Astrophysics Data System (ADS)

Kylián, O.; Hanuš, J.; Choukourov, A.; Kousal, J.; Slavínská, D.; Biederman, H.

2009-07-01

RF magnetron sputtering of a nylon target in different gas mixtures was studied in order to evaluate the capability of this process to deposit amino-rich coatings needed in a wide range of biomedical applications. It has been demonstrated that both the deposition rate of the coatings and the surface density of primary amino groups are strongly linked with working gas mixture composition. From this point of view, a sufficiently high deposition rate as well as the highest amine efficiency reaching a NH2/C value of 18% was observed in the N2/H2 discharge, which leads to the surface exhibiting a high rate of protein adsorption.

Dual functions of zirconium modification on improving the electrochemical performance of Ni-rich LiNi0.8Co0.1Mn0.1O2

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

Li, Xing; Zhang, Kangjia; Wang, Mingshan

2018-02-28

Trace amount of Zirconium (Zr) has been adopted to modify the crystal structure and surface of the Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material. During cycling at 1.0C, the Zr-modified NCM811 shows an improved capacity retention of 92% after 100 cycles, higher than 75% for pristine NMC811. In addition, the Zr-modified NCM811 is capable of delivering a discharge capacity of 107 mAh g-1 at 10.0C rate, much higher than 28 mAh g-1 delivered by pristine material. These improved electrochemical performances are ascribed to the dual functions of Zr modification. On one hand, part of the Zr enters the crystal lattice, which ismore » beneficial for reducing the Li/Ni cation mixing and enhancing the crystal stability of the cathode. On the other hand, the rest of the Zr forms a 1~2 nm thick coating layer on the surface of the NCM811 cathode, which effectively prevents the direct contact between NCM and the electrolyte, thus suppressing the detrimental interfacial reactions. Therefore, the Zr-modified LiNi0.8Co0.1Mn0.1O2 exhibited significantly enhanced cycling stability and charging/discharging rate capability in comparison with the untreated counterpart.« less

Facile preparation of a zinc-based alloy composite as a novel anode material for rechargeable lithium-ion batteries

NASA Astrophysics Data System (ADS)

Hung, Nguyen Thanh; Bae, Joonwon; Kim, Ji Hyeon; Son, Hyung Bin; Kim, Il Tae; Hur, Jaehyun

2018-01-01

We report a new Zn-based nanocomposite anode material (Zn-Ti-C) for lithium-ion batteries synthesized by thermal treatment and a high energy mechanical milling process. X-ray diffraction and high-resolution transmission electron microscopy revealed the formation of active Zn nanoparticles finely dispersed in the hybrid titanium carbide (TiC) and carbon matrix. Electrochemical analyses show that the formation of the TiC and carbon buffer matrix significantly contributed to the improved performance of the Zn-based electrode by mitigating the volume changes of the Zn nanoparticles during the charge/discharge processes. Furthermore, we optimized the stoichiometric ratio of Zn and Ti in terms of specific capacity, cycling performance, and rate capability in the presence of carbon. The material with a 2:1 atomic ratio (ZnTi(2:1)-C) exhibited the best cycle life, with a gravimetric capacity of 363.6 mAh g-1 and a volumetric capacity of 472.7 mAh cm-3 after 300 charge/discharge cycles (78.1% retention). At this ratio, Zn-Ti-C consistently showed the best rate capability measurements up to 3000 mA g-1 (85% of its capacity at 100 mA g-1). Therefore, our Zn-Ti-C composite is a promising alternative negative electrode material for lithium-ion batteries.

Excellent rate capability and cycling stability in Li+-conductive Li2SnO3-coated LiNi0.5Mn1.5O4 cathode materials for lithium-ion batteries.

PubMed

Mou, Jirong; Deng, Yunlong; Song, Zhicui; Zheng, Qiaoji; Lam, Kwok Ho; Lin, Dunmin

2018-05-22

High-voltage LiNi0.5Mn1.5O4 is a promising cathode candidate for lithium-ion batteries (LIBs) due to its considerable energy density and power density, but the material generally undergoes serious capacity fading caused by side reactions between the active material and organic electrolyte. In this work, Li+-conductive Li2SnO3 was coated on the surface of LiNi0.5Mn1.5O4 to protect the cathode against the attack of HF, mitigate the dissolution of Mn ions during cycling and improve the Li+ diffusion coefficient of the materials. Remarkable improvement in cycling stability and rate performance has been achieved in Li2SnO3-coated LiNi0.5Mn1.5O4. The 1.0 wt% Li2SnO3-coated LiNi0.5Mn1.5O4 cathode exhibits excellent cycling stability with a capacity retention of 88.2% after 150 cycles at 0.1 C and rate capability at high discharge rates of 5 C and 10 C, presenting discharge capacities of 119.5 and 112.2 mAh g-1, respectively. In particular, a significant improvement in cycling stability at 55 °C is obtained after the coating of 1.0 wt% Li2SnO3, giving a capacity retention of 86.8% after 150 cycles at 1 C and 55 °C. The present study provides a significant insight into the effective protection of Li-conductive coating materials for a high-voltage LiNi0.5Mn1.5O4 cathode material.

Effects of F-treatment on degradation of Mg 2Ni electrode fabricated by mechanical alloying

NASA Astrophysics Data System (ADS)

Kim, Jun Sung; Lee, Chang Rae; Choi, Jae Woong; Kang, Sung Goon

The effects of surface fluorination on the electrochemical charge-discharge properties of a Mg 2Ni electrode, prepared by mechanical alloying in Ni-MH batteries are investigated. After 20 h milling, Mg and Ni powder form nanocrystalline Mg 2Ni. The discharge capacity of this alloy increases greatly on the initial cycle but, due to the formation of a Mg(OH) 2 passive layer, displays rapid degradation in alkaline solution within 10 cycles. In a 6 M KOH+ x M KF electrolyte ( x=0.5, 1, and 2), a continuous and stable fluorinated layer is formed and the durability of the Mg 2Ni electrode increases marketly and a high rate discharge capability is obtained (90-100 mAh/g). Addition of 2 M KF leads to the highest durability of all the electrodes tested. The improvement is due to a thin MgF 2—flourinated layer, which reduces the charge-transfer resistance and protects the Mg 2Ni electrode from forming a Mg(OH) 2 layer.

Detection of incipient defects in cables by partial discharge signal analysis

NASA Astrophysics Data System (ADS)

Martzloff, F. D.; Simmon, E.; Steiner, J. P.; Vanbrunt, R. J.

1992-07-01

As one of the objectives of a program aimed at assessing test methods for in-situ detection of incipient defects in cables due to aging, a laboratory test system was implemented to demonstrate that the partial discharge analysis method can be successfully applied to low-voltage cables. Previous investigations generally involved cables rated 5 kV or higher, while the objective of the program focused on the lower voltages associated with the safety systems of nuclear power plants. The defect detection system implemented for the project was based on commercially available signal analysis hardware and software packages, customized for the specific purposes of the project. The test specimens included several cables of the type found in nuclear power plants, including artificial defects introduced at various points of the cable. The results indicate that indeed, partial discharge analysis is capable of detecting incipient defects in low-voltage cables. There are, however, some limitations of technical and non-technical nature that need further exploration before this method can be accepted in the industry.

Inferring Discharge at River Mouths from Water Surface Height Measurements

NASA Astrophysics Data System (ADS)

Branch, R.; Horner-Devine, A.; Chickadel, C. C.

2016-02-01

Numerical model results suggest that a relationship exists between river discharge and surface height anomalies near the mouth of rivers, which presents an opportunity to use satellite elevation data to measure discharge remotely. Here we investigate whether such a relationship can be observed in the field using airborne lidar data at the mouth of the Columbia River. Airborne Lidar data were used because current NASA altimeter data does not have high enough spatial resolution to image surface elevation along a river. NASA's Surface Water and Ocean Topography, SWOT, sensor is planned to have a spatial resolution of less than 100 m and maximum height precision of 1 cm. The magnitude and temporal duration of the elevation signal found in the lidar data will be used to determine if SWOT will have the resolution and precision capabilities to measure discharge from space. Lidar data were acquired during a range of tidal conditions and discharge rates from May through September of 2013. Our results suggest that there is a measurable surface height anomaly at the river mouth during part of the tidal cycle. A 0.7 m surface depression was found during ebb tide and a uniform surface tilt was found at slack tide. The variation of the anomaly over the tidal period presents a challenge for decoupling the tidal component from that due to the discharge.

The efficacy of an oxidation pond in mineralizing some industrial waste products with special reference to fluorene degradation: A case study

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

Ahmed, M.T.; Dewedar, A.; Mekki, L.

1999-07-01

The efficacy of the oxidation pond on the outskirts of the 10th of Ramadan, the main industrial city in Egypt, was examined. Samples of wastewater collected from the inlet and the outlet were screened for some priority pollutants. Acenaphethene and fluorene were the most frequently detected polycyclic aromatic hydrocarbons, while dimethyl phthalate was the most frequently detected phthalate ester. The spectrum of pollutants, their concentrations and frequencies were similar in the inlet and the outlet, indicating an inferior mineralization capability of the pond. Several degradative bacterial strains were isolated from the pond and grown on M56 minimal media supplemented withmore » different pollutants as the carbon source. The efficacy of pure and mixed cultures to break down fluorene, the most frequently detected pollutant was examined. Fluorene degradation was fast in the first 10 days, the followed by a slow phase. Mixed culture had a higher rate of fluorene degradation in comparison to pure cultures. High performance liquid chromatography analysis of fluorene degradation showed three degradative metabolites. But GC/MS analysis detected one compound, identified as acetamide. The present work has indicated the poor efficacy of the pond. Lack of primary treatment of industrial effluent at factory level, coupled with shock loads of toxicants that may damage the microorganisms and their degradative capabilities are presumably main factors behind such inferior performance. Moreover, the type of pollutants discharged into the pond tend to fluctuate and change depending on the rate from the factories discharge and work shifts. Such irregular feeding of persistent pollutants may have led to a wash out of specialized strains of bacteria capable to degrade such persistent pollutants.« less

ε-MnO2 nanostructures directly grown on Ni foam: a cathode catalyst for rechargeable Li-O2 batteries.

PubMed

Hu, Xiaofei; Han, Xiaopeng; Hu, Yuxiang; Cheng, Fangyi; Chen, Jun

2014-04-07

A sponge-like ε-MnO2 nanostructure was synthesized by direct growth of ε-MnO2 on Ni foam through a facile electrodeposition route. When applied as a self-supporting, binder-free cathode material for rechargeable nonaqueous lithium-oxygen batteries, the ε-MnO2/Ni electrode exhibits considerable high-rate capability (discharge capacity of ∼6300 mA h g(-1) at a current density of 500 mA g(-1)) and enhanced cyclability (exceeding 120 cycles) without controlling the discharge depth. The superior performance is proposed to be associated with the 3D nanoporous structures and abundant oxygen defects as well as the absence of side reactions related to carbon-based conductive additives and binders.

Synthesis of lithium nickel cobalt manganese oxide cathode materials by infrared induction heating

NASA Astrophysics Data System (ADS)

Hsieh, Chien-Te; Chen, Yu-Fu; Pai, Chun-Ting; Mo, Chung-Yu

2014-12-01

This study adopts an in-situ infrared (IR) sintering incorporated with carbonization technique to synthesize carbon-coated LiNi1/3Co1/3Mn1/3O2 (LNCM) cathode materials for Li-ion batteries. Compared with electric resistance heating, the in-situ IR sintering is capable of rapidly producing highly-crystalline LNCM powders at 900 °C within a short period, i.e., 3 h in this case. Glucose additive is employed to serve a carbon precursor, which is carbonized and coated over the surface of LNCM crystals during the IR sintering process. The electrochemical performance of LNCM cathodes is well examined by charge-discharge cycling at 0.1-5C. An appropriate carbon coating is capable of raising discharge capacity (i.e., 181.5 mAh g-1 at 0.1C), rate capability (i.e., 75.0 mAh g-1 at 5C), and cycling stability (i.e., capacity retention: 94.2% at 1C after 50 cycles) of LNCM cathodes. This enhanced performance can be ascribed to the carbon coating onto the external surface of LNCM powders, creating an outer circuit of charge-transfer pathway and preventing cathode corrosion from direct contact to the electrolyte. Accordingly, the in-situ IR sintering technique offers a potential feasibility for synthesizing cathode materials commercially in large scale.

In-Situ Measurement of Hall Thruster Erosion Using a Fiber Optic Regression Probe

NASA Technical Reports Server (NTRS)

Polzin, Kurt; Korman, Valentin

2009-01-01

One potential life-limiting mechanism in a Hall thruster is the erosion of the ceramic material comprising the discharge channel. This is especially true for missions that require long thrusting periods and can be problematic for lifetime qualification, especially when attempting to qualify a thruster by analysis rather than a test lasting the full duration of the mission. In addition to lifetime, several analytical and numerical models include electrode erosion as a mechanism contributing to enhanced transport properties. However, there is still a great deal of dispute over the importance of erosion to transport in Hall thrusters. The capability to perform an in-situ measurement of discharge channel erosion is useful in addressing both the lifetime and transport concerns. An in-situ measurement would allow for real-time data regarding the erosion rates at different operating points, providing a quick method for empirically anchoring any analysis geared towards lifetime qualification. Erosion rate data over a thruster s operating envelope would also be useful in the modeling of the detailed physics inside the discharge chamber. There are many different sensors and techniques that have been employed to quantify discharge channel erosion in Hall thrusters. Snapshots of the wear pattern can be obtained at regular shutdown intervals using laser profilometry. Many non-intrusive techniques of varying complexity and sensitivity have been employed to detect the time-varying presence of erosion products in the thruster plume. These include the use quartz crystal microbalances, emission spectroscopy, laser induced flourescence, and cavity ring-down spectroscopy. While these techniques can provide a very accurate picture of the level of eroded material in the thruster plume, it is more difficult to use them to determine the location from which the material was eroded. Furthermore, none of the methods cited provide a true in-situ measure of erosion at the channel surface while the thruster is in operation (i.e. none yield a continuous channel erosion measurement). A recent fundamental sensor development effort has led to a novel regression, erosion, and ablation sensor technology (REAST). The REAST sensor allows for measurement of real-time surface erosion rates at a discrete surface location. The sensor was tested using a linear Hall thruster geometry (see Fig. 1), which served as a means of producing plasma erosion of a ceramic discharge chamber. The mass flow rate, discharge voltage, and applied magnetic field strength could be varied, allowing for erosion measurements over a broad thruster operating envelope. Results are presented demonstrating the ability of the REAST sensor to capture not only the insulator erosion rates but also changes in these rates as a function of the discharge parameters.

High rate lithium/thionyl chloride bipolar battery development

NASA Technical Reports Server (NTRS)

Russell, Philip G.; Goebel, F.

1994-01-01

Presented in viewgraph format are results and accomplishments on the development of lithium/thionyl chloride bipolar batteries. Results include the development of manufacturing capability for producing large quantities of uniform cathodes and bipolar plates; the development of assembly, sealing, and activation procedures for fabrication of battery modules containing up to 150 cells in bipolar configuration; and the successful demonstration of a 10.7 kW 150-cell module with constant power pulse discharge, 20 second pulse, and 10 percent duty cycle.

Development of a hybrid battery system for an implantable biomedical device, especially a defibrillator/cardioverter (ICD)

NASA Astrophysics Data System (ADS)

Drews, Jürgen; Wolf, R.; Fehrmann, G.; Staub, R.

An implantable defibrillator battery has to provide pulse power capabilities as well as high energy density. Low self-discharge rates are mandatory and a way to check the remaining available capacity is necessary. These requirements are accomplished by a system consisting of a lithium/manganese dioxide 6 V battery, plus a lithium/iodine-cell. The use of a high rate 6 V double-cell design in combination with a high energy density cell reduces the total volume required by the power source within an implantable defibrillator. The design features and performance data of the hybrid system are described.

The effect of surface-bulk potential difference on the kinetics of intercalation in core-shell active cathode particles

NASA Astrophysics Data System (ADS)

Kazemiabnavi, Saeed; Malik, Rahul; Orvananos, Bernardo; Abdellahi, Aziz; Ceder, Gerbrand; Thornton, Katsuyo

2018-04-01

Surface modification of active cathode particles is commonly observed in battery research as either a surface phase evolving during the cycling process, or intentionally engineered to improve capacity retention, rate capability, and/or thermal stability of the cathode material. Here, a continuum-scale model is developed to simulate the galvanostatic charge/discharge of a cathode particle with core-shell heterostructure. The particle is assumed to be comprised of a core material encapsulated by a thin layer of a second phase that has a different open-circuit voltage. The effect of the potential difference between the surface and bulk phases (Ω) on the kinetics of lithium intercalation and the galvanostatic charge/discharge profiles is studied at different values of Ω, C-rates, and exchange current densities. The difference between the Li chemical potential in the surface and bulk phases of the cathode particle results in a concentration difference between these two phases. This leads to a charge/discharge asymmetry in the galvanostatic voltage profiles, causing a decrease in the accessible capacity of the particle. These effects are more significant at higher magnitudes of surface-bulk potential difference. The proposed model provides detailed insight into the kinetics and voltage behavior of the intercalation/de-intercalation processes in core-shell heterostructure cathode particles.

Probing the Complexities of Structural Changes in Layered Oxide Cathode Materials for Li-Ion Batteries during Fast Charge–Discharge Cycling and Heating

DOE PAGES

Hu, Enyuan; Wang, Xuelong; Yu, Xiqian; ...

2018-01-19

The rechargeable lithium-ion battery (LIB) is the most promising energy storage system to power electric vehicles with high energy density and long cycling life. However, in order to meet customers’ demands for fast charging, the power performances of current LIBs need to be improved. From the cathode aspect, layer-structured cathode materials are widely used in today’s market and will continue to play important roles in the near future. The high rate capability of layered cathode materials during charging and discharging is critical to the power performance of the whole cell and the thermal stability is closely related to the safetymore » issues. Therefore, the in-depth understanding of structural changes of layered cathode materials during high rate charging/discharging and the thermal stability during heating are essential in developing new materials and improving current materials. Since structural changes take place from the atomic level to the whole electrode level, combination of characterization techniques covering multilength scales is quite important. Finally, in many cases, this means using comprehensive tools involving diffraction, spectroscopy, and imaging to differentiate the surface from the bulk and to obtain structural/chemical information with different levels of spatial resolution.« less

Synthesis of hierarchical mesoporous lithium nickel cobalt manganese oxide spheres with high rate capability for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Tong, Wei; Huang, Yudai; Cai, Yanjun; Guo, Yong; Wang, Xingchao; Jia, Dianzeng; Sun, Zhipeng; Pang, Weikong; Guo, Zaiping; Zong, Jun

2018-01-01

Hierarchical mesoporous LiNi1/3Co1/3Mn1/3O2 spheres have been synthesized by urea-assisted solvothermal method with adding Triton X-100. The structure and morphology of the as-prepared materials were analyzed by X-ray diffraction and electron microscope. The results show that the as-prepared samples can be indexed as hexagonal layered structure with hierarchical architecture, and the possible formation mechanism is speculated. When evaluated as cathode material, the hierarchical mesoporous LiNi1/3Co1/3Mn1/3O2 spheres show good electrochemical properties with high initial discharge capacity of 129.9 mAh g-1, and remain the discharge capacity of 95.5 mAh g-1 after 160 cycles at 10C. The excellent electrochemical performance of the as-prepared sample can be attributed to its stable hierarchical mesoporous framework in conjunction with large specific surface, low cation mixing and small particle size. They not only provide a large number of reaction sites for surface or interface reaction, but also shorten the diffusion length of Li+ ions. Meanwhile, the mesoporous spheres composed of nanoparticles can contribute to high rate ability and buffer volume changes during charge/discharge process.

A dual coaxial nanocable sulfur composite for high-rate lithium-sulfur batteries.

PubMed

Li, Zhen; Yuan, Lixia; Yi, Ziqi; Liu, Yang; Xin, Ying; Zhang, Zhaoliang; Huang, Yunhui

2014-01-01

Lithium-sulfur batteries have great potential for some high energy applications such as in electric vehicles and smart grids due to their high capacity, natural abundance, low cost and environmental friendliness. But they suffer from rapid capacity decay and poor rate capability. The problems are mainly related to the dissolution of the intermediate polysulfides in the electrolyte, and to the poor conductivity of sulfur and the discharge products. In this work, we propose a novel dual coaxial nanocable sulfur composite fabricated with multi-walled nanotubes (MWCNT), nitrogen-doped porous carbon (NPC) and polyethylene glycol (PEG), i.e. MWCNTs@S/NPC@PEG nanocable, as a cathode material for Li-S batteries. In such a coaxial structure, the middle N-doped carbon with hierarchical porous structure provides a nanosized capsule to contain and hold the sulfur particles; the inner MWCNTs and the outer PEG layer can further ensure the fast electronic transport and prevent the dissolution of the polysulfides into the electrolyte, respectively. The as-designed MWCNT@S/NPC@PEG composite shows good cycling stability and excellent rate capability. The capacity is retained at 527 mA h g(-1) at 1 C after 100 cycles, and 791 mA h g(-1) at 0.5 C and 551 mA h g(-1) at 2 C after 50 cycles. Especially, the high-rate capability is outstanding with 400 mA h g(-1) at 5 C.

Interconnected silicon hollow nanospheres for lithium-ion battery anodes with long cycle life.

PubMed

Yao, Yan; McDowell, Matthew T; Ryu, Ill; Wu, Hui; Liu, Nian; Hu, Liangbing; Nix, William D; Cui, Yi

2011-07-13

Silicon is a promising candidate for the anode material in lithium-ion batteries due to its high theoretical specific capacity. However, volume changes during cycling cause pulverization and capacity fade, and improving cycle life is a major research challenge. Here, we report a novel interconnected Si hollow nanosphere electrode that is capable of accommodating large volume changes without pulverization during cycling. We achieved the high initial discharge capacity of 2725 mAh g(-1) with less than 8% capacity degradation every hundred cycles for 700 total cycles. Si hollow sphere electrodes also show a Coulombic efficiency of 99.5% in later cycles. Superior rate capability is demonstrated and attributed to fast lithium diffusion in the interconnected Si hollow structure.

Fast-pulverization enabled simultaneous enhancement on cycling stability and rate capability of C@NiFe2O4 hierarchical fibrous bundle

NASA Astrophysics Data System (ADS)

Chen, Zerui; Zhang, Yu; Wang, Xiaoling; Sun, Wenping; Dou, Shixue; Huang, Xin; Shi, Bi

2017-09-01

Electrochemical-grinding induced pulverization is the origin of capacity fading in NiFe2O4. Increasing current density normally accelerates the pulverization that deteriorates lithium storage properties of NiFe2O4. Here we show that the high current induced fast-pulverization can serve as an efficient activation strategy for quick and simultaneous enhancement on cycling stability and rate capability of NiFe2O4 nanoparticles (NPs) that are densely packed on the hierarchically structured carbon nanofiber strand. At a high current density, the pulverization of NiFe2O4 NPs can be accomplished in a few cycles exposing more active surface. During the fast-pulverization, the hierarchically structured carbon nanofiber strand maintains conductive contact for the densely packed NiFe2O4 NPs regardless of charge or discharge, which also effectively suppresses the repetitive breaks and growths of solid-electrolyte-interphase (SEI) via multiple-level structural adaption that favourites the quick formation of a thin and dense SEI, thus providing strong interparticle connectivity with enhancement on cycling stability and rate capability (e.g. doubled capacity). Our findings demonstrate the potential importance of high current induced fast-pulverization as an efficient activation strategy for achieving durable electrode materials suffering from electrochemical-grinding effects.

Plasma oscillation effects on nested Hall thruster operation and stability

NASA Astrophysics Data System (ADS)

McDonald, M. S.; Sekerak, M. J.; Gallimore, A. D.; Hofer, R. R.

High-power Hall thrusters capable of throughput on the order of 100 kW are currently under development, driven by more demanding mission profiles and rapid growth in on-orbit solar power generation capability. At these power levels the nested Hall thruster (NHT), a new design that concentrically packs multiple thrusters into a single body with a shared magnetic circuit, offers performance and logistical advantages over conventional single-channel Hall thrusters. An important area for risk reduction in NHT development is quantifying inter-channel coupling between discharge channels. This work presents time- and frequency-domain discharge current and voltage measurements paired with high-speed video of the X2, a 10-kW class dual channel NHT. Two “ triads” of operating conditions at 150 V, 3.6 kW and 250 V, 8.6 kW were examined, including each channel in individual operation and both channels in joint operation. For both triads tested, dual-channel operation did not noticeably destabilize the discharge. Partial coupling of outer channel oscillations into the inner channel occurred at 150 V, though oscillation amplitudes did not change greatly. As a percentage of mean discharge current, RMS oscillations at 150 V increased from 8% to 13% on the inner channel and decreased from 10% to 8% on the outer channel from single- to dual-channel operation. At 250 V the RMS/mean level stayed steady at 13% on the inner channel and decreased from 7% to 6% on the outer channel. The only mean discharge parameter noticeably affected was the cathode floating potential, which decreased in magnitude below ground with increased absolute cathode flow rate in dual-channel mode. Rotating spokes were detected on high-speed video across all X2 operating cases with wavelength 12-18 cm, and spoke velocity generally increased from single- to dual-channel operation.

Photogrammetric discharge monitoring of small tropical mountain rivers - A case study at Rivière des Pluies, Réunion island

NASA Astrophysics Data System (ADS)

Stumpf, André; Augereau, Emmanuel; Delacourt, Christophe; Bonnier, Julien

2016-04-01

Reliable discharge measurements are indispensable for an effective management of natural water resources and floods. Limitations of classical current meter profiling and stage-discharge ratings have stimulated the development of more accurate and efficient gauging techniques. While new discharge measurements technologies such as acoustic doppler current profilers and large-scale image particle velocimetry (LSPIV) have been developed and tested in numerous studies, the continuous monitoring of small mountain rivers and discharge dynamics during strong meteorological events remains challenging. More specifically LSPIV studies are often focused on short-term measurements during flood events and there are still very few studies that address its use for long-term monitoring of small mountain rivers. To fill this gap this study targets the development and testing of largely autonomous photogrammetric discharge measurement system with a special focus on the application to small mountain river with high discharge variability and a mobile riverbed in the tropics. It proposes several enhancements among previous LSPIV methods regarding camera calibration, more efficient processing in image geometry, the automatic detection of the water level as well as the statistical calibration and estimation of the discharge from multiple profiles. To account for changes in the bed topography the riverbed is surveyed repeatedly during the dry seasons using multi-view photogrammetry or terrestrial laser scanners. The presented case study comprises the analysis of several thousand videos spanning over two and a half year (2013-2015) to test the robustness and accuracy of different processing steps. An analysis of the obtained results suggests that the quality of the camera calibration reaches a sub-pixel accuracy. The median accuracy of the watermask detections is F1=0.82, whereas the precision is systematically higher than the recall. The resulting underestimation of the water surface area and level leads to a systematic underestimation of the discharge and error rates of up to 25 %. However, the bias can be effectively removed using a least-square cross-calibration which reduces the error to a MAE of 6.39% and a maximum error of 16.18%. Those error rates are significantly lower than the uncertainties among multiple profiles (30%) and illustrate the importance of the spatial averaging from multiple measurements. The study suggests that LSPIV can already be considered as a valuable tool for the monitoring of torrential flows, whereas further research is still needed to fully integrate night-time observation and stereo-photogrammetric capabilities.

Spacecraft utensil/hand cleansing fixture. [for space shuttles

NASA Technical Reports Server (NTRS)

Rosener, A. A.; Jonkoniec, T. G.; Wilson, D. A.; Schulz, J. R.

1975-01-01

A system concept for an inflight utensil/hand cleansing fixture is described which includes the following features: (1) capability for efficient cleansing and rinsing of utensils or hands, and (2) provision for general waste fluid disposal. The design concept provides for the capability of functioning for a 30 day shuttle mission containing seven occupants/users. The long range goal is to provide a functioning system capable of operating for missions of at least 120 days. The fixture is a self-contained unit that can be installed in the standard water interface requirements. Service to the unit is a single source of unheated potable water and water is discharged from the unit into a single return waste connection. In addition, the design includes provisions for the intake and discharge of purge air and the discharge of evolved gases. Both the air and the gases are filtered or processed in the assembly before releasing them into the habitability area.

Hierarchical network architectures of carbon fiber paper supported cobalt oxide nanonet for high-capacity pseudocapacitors.

PubMed

Yang, Lei; Cheng, Shuang; Ding, Yong; Zhu, Xingbao; Wang, Zhong Lin; Liu, Meilin

2012-01-11

We present a high-capacity pseudocapacitor based on a hierarchical network architecture consisting of Co(3)O(4) nanowire network (nanonet) coated on a carbon fiber paper. With this tailored architecture, the electrode shows ideal capacitive behavior (rectangular shape of cyclic voltammograms) and large specific capacitance (1124 F/g) at high charge/discharge rate (25.34 A/g), still retaining ~94% of the capacitance at a much lower rate of 0.25 A/g. The much-improved capacity, rate capability, and cycling stability may be attributed to the unique hierarchical network structures, which improves electron/ion transport, enhances the kinetics of redox reactions, and facilitates facile stress relaxation during cycling. © 2011 American Chemical Society

Antarctic ice discharge due to warm water intrusion into shelf cavities

NASA Astrophysics Data System (ADS)

Winkelmann, R.; Reese, R.; Albrecht, T.; Mengel, M.; Asay-Davis, X.

2017-12-01

Ocean-induced melting below ice shelves is the dominant driver for mass loss from the Antarctic Ice Sheet at present. Observations show that many Antarctic ice shelves are thinning which reduces their buttressing potential and can lead to increased ice discharge from the glaciers upstream. Melt rates from Antarctic ice shelves are determined by the temperature and salinity of the ambient ocean. In many parts, ice shelves are shielded by clearly defined density fronts which keep relatively warm Northern water from entering the cavity underneath the ice shelves. Projections show that a redirection of coastal currents might allow these warmer waters to intrude into ice shelf cavities, for instance in the Weddell Sea, and thereby cause a strong increase in sub-shelf melt rates. Using the Potsdam Ice-shelf Cavity mOdel (PICO), we assess how such a change would influence the dynamic ice loss from Antarctica. PICO is implemented as part of the Parallel Ice Sheet Model (PISM) and mimics the vertical overturning circulation in ice-shelf cavities. The model is capable of capturing the wide range of melt rates currently observed for Antarctic ice shelves and reproduces the typical pattern of comparably high melting near the grounding line and lower melting or refreezing towards the calving front. Based on regional observations of ocean temperatures, we use PISM-PICO to estimate an upper limit for ice discharge resulting from the potential erosion of ocean fronts around Antarctica.

Secondary cell with orthorhombic alkali metal/manganese oxide phase active cathode material

DOEpatents

Doeff, Marca M.; Peng, Marcus Y.; Ma, Yanping; Visco, Steven J.; DeJonghe, Lutgard C.

1996-01-01

An alkali metal manganese oxide secondary cell is disclosed which can provide a high rate of discharge, good cycling capabilities, good stability of the cathode material, high specific energy (energy per unit of weight) and high energy density (energy per unit volume). The active material in the anode is an alkali metal and the active material in the cathode comprises an orthorhombic alkali metal manganese oxide which undergoes intercalation and deintercalation without a change in phase, resulting in a substantially linear change in voltage with change in the state of charge of the cell. The active material in the cathode is an orthorhombic structure having the formula M.sub.x Z.sub.y Mn.sub.(1-y) O.sub.2, where M is an alkali metal; Z is a metal capable of substituting for manganese in the orthorhombic structure such as iron, cobalt or titanium; x ranges from about 0.2 in the fully charged state to about 0.75 in the fully discharged state, and y ranges from 0 to 60 atomic %. Preferably, the cell is constructed with a solid electrolyte, but a liquid or gelatinous electrolyte may also be used in the cell.

Secondary cell with orthorhombic alkali metal/manganese oxide phase active cathode material

DOEpatents

Doeff, M.M.; Peng, M.Y.; Ma, Y.; Visco, S.J.; DeJonghe, L.C.

1996-09-24

An alkali metal manganese oxide secondary cell is disclosed which can provide a high rate of discharge, good cycling capabilities, good stability of the cathode material, high specific energy (energy per unit of weight) and high energy density (energy per unit volume). The active material in the anode is an alkali metal and the active material in the cathode comprises an orthorhombic alkali metal manganese oxide which undergoes intercalation and deintercalation without a change in phase, resulting in a substantially linear change in voltage with change in the state of charge of the cell. The active material in the cathode is an orthorhombic structure having the formula M{sub x}Z{sub y}Mn{sub (1{minus}y)}O{sub 2}, where M is an alkali metal; Z is a metal capable of substituting for manganese in the orthorhombic structure such as iron, cobalt or titanium; x ranges from about 0.2 in the fully charged state to about 0.75 in the fully discharged state, and y ranges from 0 to 60 atomic %. Preferably, the cell is constructed with a solid electrolyte, but a liquid or gelatinous electrolyte may also be used in the cell. 11 figs.

The importance of “going nano” for high power battery materials

NASA Astrophysics Data System (ADS)

Bresser, Dominic; Paillard, Elie; Copley, Mark; Bishop, Peter; Winter, Martin; Passerini, Stefano

2012-12-01

The electrochemical performance of spinel Li4Ti5O12 (LTO) nanoparticles synthesized by flame spray pyrolysis with an average diameter of approximately 20-30 nm is reported in this manuscript and compared with that of micro-sized LTO particles (1-2 μm) formed by a thermal post-treatment of the nanoparticles. The significantly advanced high rate capability of nano-sized LTO is evidenced by the results from the galvanostatic tests with applied current densities of up to 17.5 A g-1, corresponding to a full (dis-)charge of the cell within less than 40 s. For nano-sized LTO, specific capacities of 115 and 70 mAh g-1 were obtained for applied rates of 10 C and 100 C, respectively, thus confirming the essential influence of particle size of lithium titanate on its high rate capability and practical power density. Moreover, a capacity retention of around 94.8% was observed after 1000 cycles at 10 C, presenting LTO nanoparticles synthesized by FSP as highly promising anode material for high power lithium-ion battery applications.

A Porphyrin Complex as a Self-Conditioned Electrode Material for High-Performance Energy Storage.

PubMed

Gao, Ping; Chen, Zhi; Zhao-Karger, Zhirong; Mueller, Jonathan E; Jung, Christoph; Klyatskaya, Svetlana; Diemant, Thomas; Fuhr, Olaf; Jacob, Timo; Behm, R Jürgen; Ruben, Mario; Fichtner, Maximilian

2017-08-21

The novel functionalized porphyrin [5,15-bis(ethynyl)-10,20-diphenylporphinato]copper(II) (CuDEPP) was used as electrodes for rechargeable energy-storage systems with an extraordinary combination of storage capacity, rate capability, and cycling stability. The ability of CuDEPP to serve as an electron donor or acceptor supports various energy-storage applications. Combined with a lithium negative electrode, the CuDEPP electrode exhibited a long cycle life of several thousand cycles and fast charge-discharge rates up to 53 C and a specific energy density of 345 Wh kg -1 at a specific power density of 29 kW kg -1 . Coupled with a graphite cathode, the CuDEPP anode delivered a specific power density of 14 kW kg -1 . Whereas the capacity is in the range of that of ordinary lithium-ion batteries, the CuDEPP electrode has a power density in the range of that of supercapacitors, thus opening a pathway toward new organic electrodes with excellent rate capability and cyclic stability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface modified CF x cathode material for ultrafast discharge and high energy density

DOE PAGES

Dai, Yang; Zhu, Yimei; Cai, Sendan; ...

2014-11-10

Li/CF x primary possesses the highest energy density of 2180 W h kg⁻¹ among all primary lithium batteries. However, a key limitation for the utility of this type of battery is in its poor rate capability because the cathode material, CF x, is an intrinsically poor electronic conductor. Here, we report on our development of a controlled process of surface de-fluorination under mild hydrothermal conditions to modify the highly fluorinated CF x. The modified CF x, consisting of an in situ generated shell component of F-graphene layers, possesses good electronic conductivity and removes the transporting barrier for lithium ions, yieldingmore » a high-capacity performance and an excellent rate-capability. Indeed, a capacity of 500 mA h g⁻¹ and a maximum power density of 44 800 W kg⁻¹ can be realized at the ultrafast rate of 30 C (24 A g⁻¹), which is over one order of magnitude higher than that of the state-of-the-art primary lithium-ion batteries.« less

Acetylene Black Induced Heterogeneous Growth of Macroporous CoV2O6 Nanosheet for High-Rate Pseudocapacitive Lithium-Ion Battery Anode.

PubMed

Zhang, Lei; Zhao, Kangning; Luo, Yanzhu; Dong, Yifan; Xu, Wangwang; Yan, Mengyu; Ren, Wenhao; Zhou, Liang; Qu, Longbing; Mai, Liqiang

2016-03-23

Metal vanadates suffer from fast capacity fading in lithium-ion batteries especially at a high rate. Pseudocapacitance, which is associated with surface or near-surface redox reactions, can provide fast charge/discharge capacity free from diffusion-controlled intercalation processes and is able to address the above issue. In this work, we report the synthesis of macroporous CoV2O6 nanosheets through a facile one-pot method via acetylene black induced heterogeneous growth. When applied as lithium-ion battery anode, the macroporous CoV2O6 nanosheets show typical features of pseudocapacitive behavior: (1) currents that are mostly linearly dependent on sweep rate and (2) redox peaks whose potentials do not shift significantly with sweep rate. The macroporous CoV2O6 nanosheets display a high reversible capacity of 702 mAh g(-1) at 200 mA g(-1), excellent cyclability with a capacity retention of 89% (against the second cycle) after 500 cycles at 500 mA g(-1), and high rate capability of 453 mAh g(-1) at 5000 mA g(-1). We believe that the introduction of pseudocapacitive properties in lithium battery is a promising direction for developing electrode materials with high-rate capability.

Enhancement of the electrochemical performance of hydrothermally prepared anatase nanoparticles for optimal use as high capacity anode materials in lithium ion batteries (LIBs)

NASA Astrophysics Data System (ADS)

Sanad, M. M. S.; Rashad, M. M.; Powers, K.

2015-02-01

Mesoporous TiO2 nanoparticles have been synthesized via facile hydrolytic hydrothermal technique without incorporation any template. The precious metallic nanoparticles; Ag, Pt and Pd have been embedded between the anatase particles using in situ reduction step. The structural properties of the as-synthesized samples were investigated by X-ray diffraction, transmission electron microscopic and N2 adsorption-desorption isotherm ( S BET). The electrochemical studies for the as-prepared anode materials including, cyclic voltammetry and electrochemical impedance spectroscopy indicated a significant improvement in the electronic conductivity of the lithium-TiO2 cells. Therefore, the charge-discharge rates were noticeably promoted as a result of the enhancement of Li-ion diffusion and charge transfer. The cycling results of Pd-TiO2 revealed a marvelous improvement in both charge and discharge capacities by 89.4 and 88 % after 10 cycles at C/5 rate. Generally, all the as-prepared TiO2 nanocomposites showed enhanced specific capacity, cycling stability and rate capability compared to the pure TiO2, providing a promising behavior for use as anodes in lithium ion batteries (LIBs).

Novel layered polyaniline-poly(hydroquinone)/graphene film as supercapacitor electrode with enhanced rate performance and cycling stability.

PubMed

Ren, Lijun; Zhang, Gaini; Lei, Ji; Wang, Yan; Hu, Dengwei

2018-02-15

It is a challenge to fabricate polyaniline (PANI) materials with high rate performance and excellent stability. Herein a new special supercapacitor electrode material of polyaniline-poly(hydroquinone)/graphene (PANI-PHQ/RGO) film with layered structure was prepared by chemical oxidative polymerization of aniline and hydroquinone (H 2 Q) in the presence of RGO hydrogel film. The synergistic effect and loose layered structure of the composite film facilitate fast diffusion and transportation of electrolyte ions through unimpeded channels during rapid charge-discharge process, resulting in high rate capability and stable cycling performance. As a result, the PANI-PHQ/RGO-61 film electrode exhibited 356 F g -1 at a current density of 0.5 A g -1 and high capacitance retention of 83% from 0.5 to 30 A g -1 . Moreover, it presented an excellent cycling stability with 94% of capacitance retention in comparison with 60% of pure PANI electrode and an outstanding Coulombic efficiency of 99% after 1000 cycles of galvanostatic charge-discharge. These superior electrocapacitive properties make it one of promising candidates for electrochemical energy storage. Copyright © 2017 Elsevier Inc. All rights reserved.

The inter-ELM tungsten erosion profile in DIII-D H-mode discharges and benchmarking with ERO+OEDGE modeling [The inter-ELM W erosion profile in DIII-D H-mode discharges and benchmarking with OEDGE+ERO modeling

DOE PAGES

Abrams, Tyler; Ding, Rui; Guo, Houyang Y.; ...

2017-04-03

It is important to develop a predictive capability for the tungsten source rate near the strike points during H-mode operation in ITER and beyond. H-mode deuterium plasma exposures were performed on W-coated graphite and TZM molybdenum substrates in the DIII-D divertor using DiMES. The W-I 400.9 nm spectral line was monitored by fast filtered diagnostics cross calibrated via a high-resolution spectrometer to resolve inter-ELM W erosion. The effective ionization/photon (S/XB) was calibrated using a unique method developed on DIII-D based on surface analysis. Inferred S/XB values agree with an existing empirical scaling at low electron density (n e) but divergemore » at higher densities, consistent with recent ADAS atomic physics modeling results. Edge modeling of the inter-ELM phase is conducted via OEDGE utilizing the new capability for charge-state resolved carbon impurity fluxes. ERO modeling is performed with the calculated main ion and impurity plasma background from OEDGE. ERO results demonstrate the importance a mixed-material surface model in the interpretation of W sourcing measurements. As a result, it is demonstrated that measured inter-ELM W erosion rates can be well explained by C→W sputtering only if a realistic mixed material model is incorporated.« less

The inter-ELM tungsten erosion profile in DIII-D H-mode discharges and benchmarking with ERO+OEDGE modeling [The inter-ELM W erosion profile in DIII-D H-mode discharges and benchmarking with OEDGE+ERO modeling

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

Abrams, Tyler; Ding, Rui; Guo, Houyang Y.

It is important to develop a predictive capability for the tungsten source rate near the strike points during H-mode operation in ITER and beyond. H-mode deuterium plasma exposures were performed on W-coated graphite and TZM molybdenum substrates in the DIII-D divertor using DiMES. The W-I 400.9 nm spectral line was monitored by fast filtered diagnostics cross calibrated via a high-resolution spectrometer to resolve inter-ELM W erosion. The effective ionization/photon (S/XB) was calibrated using a unique method developed on DIII-D based on surface analysis. Inferred S/XB values agree with an existing empirical scaling at low electron density (n e) but divergemore » at higher densities, consistent with recent ADAS atomic physics modeling results. Edge modeling of the inter-ELM phase is conducted via OEDGE utilizing the new capability for charge-state resolved carbon impurity fluxes. ERO modeling is performed with the calculated main ion and impurity plasma background from OEDGE. ERO results demonstrate the importance a mixed-material surface model in the interpretation of W sourcing measurements. As a result, it is demonstrated that measured inter-ELM W erosion rates can be well explained by C→W sputtering only if a realistic mixed material model is incorporated.« less

Nanosheet-assembled NiO microstructures for high-performance supercapacitors.

PubMed

Purushothaman, Kamatchi Kamaraj; Babu, Inbamani Manohara; Sethuraman, Balasubramanian; Muralidharan, Gopalan

2013-11-13

Nanosheet-assembled NiO microstructures have been synthesized via a hydrothermal method. The presence of anionic surfactant in the fabrication process initiates the formation of lamellar micelles and a self-assembling process. This leads to the formation of NiO nanosheets and organizes it into microstructures. The effect of preparation temperature on the morphological, structural, and electrochemical properties and stability upon continuous charge/discharge cycles has been examined for supercapacitor applications. Electrochemical analysis demonstrated that NiO nanosheets prepared at 160 °C are capable of delivering a specific capacitance of 989 F g(-1) at a scan rate of 3 mV s(-1) for the potential window of 0-0.6 V. The nanosheets exhibit excellent capacity retention, 97% retention after 1000 continuous charge/discharge cycles, and an energy density of 49.45 W h kg(-1).

Nickel-metal hydride (Ni-MH) batteries for aircraft power

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

Erbacher, J.K.; Kruchek, C.L.; Vukson, S.P.

1995-12-31

Commercial nickel metal hydride (Ni-MH) batteries are under evaluation for potential application as a replacement for existing Ni-Cd and Pb-Acid batteries currently used by the USAF. Replacement of these batteries is desirable due to the high cost of maintenance and acquisition, the environmental hazards associated with worker exposure to hazardous materials, and the high cost of reclamation programs for these existing batteries. Both cylindrical and prismatic AB5 cells show promise for this application, but will require alloy and single cell development to reduce self-discharge, increase discharge and charge rates, and expand the temperature range to meet austere military environments. Testedmore » AB{sub 2} cylindrical cell technology appear inadequate to meet military requirements although these cells show better charge capability at 71 C than AB{sub 5} cylindrical or prismatic cells.« less

Li+ /Mg2+ Hybrid-Ion Batteries with Long Cycle Life and High Rate Capability Employing MoS2 Nano Flowers as the Cathode Material.

PubMed

Ju, Yanming; Meng, Yuan; Wei, Yingjin; Bian, Xiaofei; Pang, Qiang; Gao, Yu; Du, Fei; Liu, Bingbing; Chen, Gang

2016-12-12

The demand for large-scale and safe energy storage is increasing rapidly due to the strong push for smartphones and electric vehicles. As a result, Li + /Mg 2+ hybrid-ion batteries (LMIBs) combining a dendrite-free deposition of Mg anode and Li + intercalation cathode have attracted considerable attention. Here, a LMIB with hydrothermal-prepared MoS 2 nano flowers as cathode material was prepared. The battery showed remarkable electrochemical properties with a large discharge capacity (243 mAh g -1 at the 0.1 C rate), excellent rate capability (108 mAh g -1 at the 5 C rate), and long cycle life (87.2 % capacity retention after 2300 cycles). Electrochemical analysis showed that the reactions occurring in the battery cell involved Mg stripping/plating at the anode side and Li + intercalation at the cathode side with a small contribution from Mg 2+ adsorption. The excellent electrochemical performance and extremely safe cell system show promise for its use in practical applications. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoarchitectured Nb2O5 hollow, Nb2O5@carbon and NbO2@carbon Core-Shell Microspheres for Ultrahigh-Rate Intercalation Pseudocapacitors

NASA Astrophysics Data System (ADS)

Kong, Lingping; Zhang, Chuanfang; Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

2016-02-01

Li-ion intercalation materials with extremely high rate capability will blur the distinction between batteries and supercapacitors. We construct a series of nanoarchitectured intercalation materials including orthorhombic (o-) Nb2O5 hollow microspheres, o-Nb2O5@carbon core-shell microspheres and tetragonal (t-) NbO2@carbon core-shell microspheres, through a one-pot hydrothermal method with different post-treatments. These nanoarchitectured materials consist of small nanocrystals with highly exposed active surface, and all of them demonstrate good Li+ intercalation pseudocapacitive properties. In particular, o-Nb2O5 hollow microspheres can deliver the specific capacitance of 488.3 F g-1, and good rate performance of 126.7 F g-1 at 50 A g-1. The o-Nb2O5@carbon core-shell microspheres show enhanced specific capacitance of 502.2 F g-1 and much improved rate performance (213.4 F g-1 at 50 A g-1). Furthermore, we demonstrate for the first time, t-NbO2 exhibits much higher rate capability than o-Nb2O5. For discharging time as fast as 5.9 s (50 A g-1), it still exhibits a very high specific capacitance of 245.8 F g-1, which is 65.2% retention of the initial capacitance (377.0 F g-1 at 1 A g-1). The unprecedented rate capability is an intrinsic feature of t-NbO2, which may be due to the conductive lithiated compounds.

Nanoarchitectured Nb2O5 hollow, Nb2O5@carbon and NbO2@carbon Core-Shell Microspheres for Ultrahigh-Rate Intercalation Pseudocapacitors

PubMed Central

Kong, Lingping; Zhang, Chuanfang; Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

2016-01-01

Li-ion intercalation materials with extremely high rate capability will blur the distinction between batteries and supercapacitors. We construct a series of nanoarchitectured intercalation materials including orthorhombic (o-) Nb2O5 hollow microspheres, o-Nb2O5@carbon core-shell microspheres and tetragonal (t-) NbO2@carbon core-shell microspheres, through a one-pot hydrothermal method with different post-treatments. These nanoarchitectured materials consist of small nanocrystals with highly exposed active surface, and all of them demonstrate good Li+ intercalation pseudocapacitive properties. In particular, o-Nb2O5 hollow microspheres can deliver the specific capacitance of 488.3 F g−1, and good rate performance of 126.7 F g−1 at 50 A g−1. The o-Nb2O5@carbon core-shell microspheres show enhanced specific capacitance of 502.2 F g−1 and much improved rate performance (213.4 F g−1 at 50 A g−1). Furthermore, we demonstrate for the first time, t-NbO2 exhibits much higher rate capability than o-Nb2O5. For discharging time as fast as 5.9 s (50 A g−1), it still exhibits a very high specific capacitance of 245.8 F g−1, which is 65.2% retention of the initial capacitance (377.0 F g−1 at 1 A g−1). The unprecedented rate capability is an intrinsic feature of t-NbO2, which may be due to the conductive lithiated compounds. PMID:26880276

Fast repetition rate (FRR) flasher

DOEpatents

Kolber, Zbigniew; Falkowski, Paul

1997-02-11

A fast repetition rate (FRR) flasher suitable for high flash photolysis including kinetic chemical and biological analysis. The flasher includes a power supply, a discharge capacitor operably connected to be charged by the power supply, and a flash lamp for producing a series of flashes in response to discharge of the discharge capacitor. A triggering circuit operably connected to the flash lamp initially ionizes the flash lamp. A current switch is operably connected between the flash lamp and the discharge capacitor. The current switch has at least one insulated gate bipolar transistor for switching current that is operable to initiate a controllable discharge of the discharge capacitor through the flash lamp. Control means connected to the current switch for controlling the rate of discharge of the discharge capacitor thereby to effectively keep the flash lamp in an ionized state between Successive discharges of the discharge capacitor. Advantageously, the control means is operable to discharge the discharge capacitor at a rate greater than 10,000 Hz and even up to a rate greater than about 250,000 Hz.

Superior supercapacitors based on nitrogen and sulfur co-doped hierarchical porous carbon: Excellent rate capability and cycle stability

NASA Astrophysics Data System (ADS)

Zhang, Deyi; Han, Mei; Wang, Bing; Li, Yubing; Lei, Longyan; Wang, Kunjie; Wang, Yi; Zhang, Liang; Feng, Huixia

2017-08-01

Vastly improving the charge storage capability of supercapacitors without sacrificing their high power density and cycle performance would bring bright application prospect. Herein, we report a nitrogen and sulfur co-doped hierarchical porous carbon (NSHPC) with very superior capacitance performance fabricated by KOH activation of nitrogen and sulfur co-doped ordered mesoporous carbon (NSOMC). A high electrochemical double-layer (EDL) capacitance of 351 F g-1 was observed for the reported NSHPC electrodes, and the capacitance remains at 288 F g-1 even under a large current density of 20 A g-1. Besides the high specific capacitance and outstanding rate capability, symmetrical supercapacitor cell based on the NSHPC electrodes also exhibits an excellent cycling performance with 95.61% capacitance retention after 5000 times charge/discharge cycles. The large surface area caused by KOH activation (2056 m2 g-1) and high utilized surface area owing to the ideal micro/mesopores ratio (2.88), large micropores diameter (1.38 nm) and short opened micropores structure as well as the enhanced surface wettability induced by N and S heteroatoms doping and improved conductivity induced by KOH activation was found to be responsible for the very superior capacitance performance.

Top-Down Strategy to Synthesize Mesoporous Dual Carbon Armored MnO Nanoparticles for Lithium-Ion Battery Anodes.

PubMed

Zhang, Wei; Li, Jiannian; Zhang, Jie; Sheng, Jinzhi; He, Ting; Tian, Meiyue; Zhao, Yufeng; Xie, Changjun; Mai, Liqiang; Mu, Shichun

2017-04-12

To overcome inferior rate capability and cycle stability of MnO-based materials as a lithium-ion battery anode associated with the pulverization and gradual aggregation during the conversion process, we constructed robust mesoporous N-doped carbon (N-C) protected MnO nanoparticles on reduced graphene oxide (rGO) (MnO@N-C/rGO) by a simple top-down incorporation strategy. Such dual carbon protection endows MnO@N-C/rGO with excellent structural stability and enhanced charge transfer kinetics. At 100 mA g -1 , it exhibits superior rate capability as high as 864.7 mAh g -1 , undergoing the deep charge/discharge for 70 cycles and outstanding cyclic stability (after 1300 cyclic tests at 2000 mA g -1 ; 425.0 mAh g -1 remains, accompanying merely 0.004% capacity decay per cycle). This facile method provides a novel strategy for synthesis of porous electrodes by making use of highly insulating materials.

Discharge rate measurements in a canal using radiotracer methods.

PubMed

Pant, H J; Goswami, Sunil; Biswal, Jayashree; Samantray, J S; Sharma, V K

2016-06-01

Discharge rates of water were measured in a canal using radiotracer methods with an objective to validate the efficacy of Concrete Volute Pumps (CVPs) installed at various pumping stations along the canal. Pulse velocity and dilution methods were applied to measure the discharge rates using Iodine-131 as a radiotracer. The discharge rate measured in one of the sections of the canal using the pulse velocity method was found to be 22.5m(3)/s, whereas the discharge rates measured using the dilution method in four different sections of the canal varied from 20.27 to 20.62m(3)/s with single CVP in operation. The standard error in discharge rate measurements using dilution method ranged from ±1.1 to ±1.8%. The experimentally measured values of the discharge rate were in good agreement with the design value of the discharge rate (20m(3)/s) thus validating the performance of the CVPs used in the canal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structurally tailored graphene nanosheets as lithium ion battery anodes: an insight to yield exceptionally high lithium storage performance

NASA Astrophysics Data System (ADS)

Li, Xifei; Hu, Yuhai; Liu, Jian; Lushington, Andrew; Li, Ruying; Sun, Xueliang

2013-11-01

How to tune graphene nanosheets (GNSs) with various morphologies has been a significant challenge for lithium ion batteries (LIBs). In this study, three types of GNSs with varying size, edge sites, defects and layer numbers have been successfully achieved. It was demonstrated that controlling GNS morphology and microstructure has important effects on its cyclic performance and rate capability in LIBs. Diminished GNS layer number, decreased size, increased edge sites and increased defects in the GNS anode can be highly beneficial to lithium storage and result in increased electrochemical performance. Interestingly, GNSs treated with a hydrothermal approach delivered a high reversible discharge capacity of 1348 mA h g-1. This study demonstrates that the controlled design of high performance GNS anodes is an important concept in LIB applications.How to tune graphene nanosheets (GNSs) with various morphologies has been a significant challenge for lithium ion batteries (LIBs). In this study, three types of GNSs with varying size, edge sites, defects and layer numbers have been successfully achieved. It was demonstrated that controlling GNS morphology and microstructure has important effects on its cyclic performance and rate capability in LIBs. Diminished GNS layer number, decreased size, increased edge sites and increased defects in the GNS anode can be highly beneficial to lithium storage and result in increased electrochemical performance. Interestingly, GNSs treated with a hydrothermal approach delivered a high reversible discharge capacity of 1348 mA h g-1. This study demonstrates that the controlled design of high performance GNS anodes is an important concept in LIB applications. Electronic supplementary information (ESI) available: SEM morphologies of GNS-I-III at low magnification, the TEM image of GNSs hydrothermally treated with urea in a ratio of 1 : 0, XPS survey, and SEM morphology changes of the three GNS anodes at low magnification after 100 charge-discharge cycles. See DOI: 10.1039/c3nr04823c

Electrochemical performance and structure evolution of core-shell nano-ring α-Fe2O3@Carbon anodes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Sun, Yan-Hui; Liu, Shan; Zhou, Feng-Chen; Nan, Jun-Min

2016-12-01

Core-shell nano-ring α-Fe2O3@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe2O3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe2O3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe2O3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g-1 and retains 920/897 mAh g-1 after 200 cycles at 500 mA g-1 (0.5C). Even at 2000 mA g-1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g-1, and still maintains 630/610 mAh g-1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe2O3@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe2O3 and facilitate the transportation of electrons and Li+ ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe2O3@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

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

Hu, Enyuan; Wang, Xuelong; Yu, Xiqian

The rechargeable lithium-ion battery (LIB) is the most promising energy storage system to power electric vehicles with high energy density and long cycling life. However, in order to meet customers’ demands for fast charging, the power performances of current LIBs need to be improved. From the cathode aspect, layer-structured cathode materials are widely used in today’s market and will continue to play important roles in the near future. The high rate capability of layered cathode materials during charging and discharging is critical to the power performance of the whole cell and the thermal stability is closely related to the safetymore » issues. Therefore, the in-depth understanding of structural changes of layered cathode materials during high rate charging/discharging and the thermal stability during heating are essential in developing new materials and improving current materials. Since structural changes take place from the atomic level to the whole electrode level, combination of characterization techniques covering multilength scales is quite important. Finally, in many cases, this means using comprehensive tools involving diffraction, spectroscopy, and imaging to differentiate the surface from the bulk and to obtain structural/chemical information with different levels of spatial resolution.« less

The influence of the carbonate species on LiNi0.8Co0.15Al0.05O2 surfaces for all-solid-state lithium ion battery performance

NASA Astrophysics Data System (ADS)

Visbal, Heidy; Fujiki, Satoshi; Aihara, Yuichi; Watanabe, Taku; Park, Youngsin; Doo, Seokgwang

2014-12-01

The influence of selected carbonate species on LiNi0.8Co0.15Al0.05O2 (NCA) surface for all-solid-state lithium-ion battery (ASSB) with a sulfide based solid electrolyte was studied for its electrochemical properties, structural stabilities, and surface characteristics. The rated discharge performance improved with the reduction of the carbonate concentration on the NCA surface due to the decrease of the interface resistance. The species and coordination of the adsorbed carbonates on the NCA surface were analyzed by diffuse reflectance Fourier transformed infrared (DRIFT) spectroscopy. The coordination of the adsorbed carbonate anion was determined based on the degree of splitting of the ν3(CO) stretching vibrations. It is found that the surface carbonate species exists in an unidentate coordination on the surface. They react with the sulfide electrolyte to form an irreversible passivation layer. This layer obstructs the charge transfer process at the cathode/electrolyte interface, and results in the rise of the interface resistance and drop of the rated discharge capability.

Characterization of a High Current, Long Life Hollow Cathode

NASA Technical Reports Server (NTRS)

VanNoord, Jonathan L.; Kamhawi, Hani; McEwen, Heather K.

2006-01-01

The advent of higher power spacecraft makes it desirable to use higher power electric propulsion thrusters such as ion thrusters or Hall thrusters. Higher power thrusters require cathodes that are capable of producing higher currents. One application of these higher power spacecraft is deep-space missions that require tens of thousands of hours of operation. This paper presents the approach used to design a high current, long life hollow cathode assembly for that application, along with test results from the corresponding hollow cathode. The design approach used for the candidate hollow cathode was to reduce the temperature gradient in the insert, yielding a lower peak temperature and allowing current to be produced more uniformly along the insert. The lower temperatures result in a hollow cathode with increased life. The hollow cathode designed was successfully operated at currents from 10 to 60 A with flow rates of 5 to 19 sccm with a maximum orifice temperature measured of 1100 C. Data including discharge voltage, keeper voltage, discharge current, flow rates, and orifice plate temperatures are presented.

Apparatus for atmospheric pressure pin-to-hole spark discharge and uses thereof

DOEpatents

Dobrynin, Danil V.; Fridman, Alexander; Cho, Young I.; Fridman, Gregory; Friedman, Gennady

2016-12-06

Disclosed herein are atmospheric pressure pin-to-hole pulsed spark discharge devices and methods for creating plasma. The devices include a conduit for fluidically communicating a gas, a plasma, or both, therethrough, portion of the conduit capable of being connected to a gas supply, and a second portion of the conduit capable of emitting a plasma; a positive electrode comprising a sharp tip; and a ground plate electrode. Disclosed are methods for treating a skin ulcer using non-thermal plasma include flowing a gas through a cold spark discharge zone simultaneously with the creation of a pulsed spark discharge to give rise to a non-thermal plasma emitted from a conduit, the non-thermal plasma comprising NO; and contacting a skin ulcer with said non-thermal plasma for sufficient time and intensity to give rise to treatment of the skin ulcer.

High specific energy, high capacity nickel-hydrogen cell design

NASA Technical Reports Server (NTRS)

Wheeler, James R.

1993-01-01

A 3.5 inch rabbit-ear-terminal nickel-hydrogen cell was designed and tested to deliver high capacity at steady discharge rates up to and including a C rate. Its specific energy yield of 60.6 wh/kg is believed to be the highest yet achieved in a slurry-process nickel-hydrogen cell, and its 10 C capacity of 113.9 AH the highest capacity yet of any type in a 3.5 inch diameter size. The cell also demonstrated a pulse capability of 180 amps for 20 seconds. Specific cell parameters and performance are described. Also covered is an episode of capacity fading due to electrode swelling and its successful recovery by means of additional activation procedures.

High-Energy-Density Electrolytic Capacitors

NASA Technical Reports Server (NTRS)

Yen, Shiao-Ping S.; Lewis, Carol R.

1993-01-01

Reductions in weight and volume make new application possible. Supercapacitors and improved ultracapacitors advanced electrolytic capacitors developed for use as electric-load-leveling devices in such applications as electric vehicle propulsion systems, portable power tools, and low-voltage pulsed power supplies. One primary advantage: offer power densities much higher than storage batteries. Capacitors used in pulse mode, with short charge and discharge times. Derived from commercially available ultracapacitors. Made of lightweight materials; incorporate electrode/electrolyte material systems capable of operation at voltages higher than previous electrode/electrolyte systems. By use of innovative designs and manufacturing processes, made in wide range of rated capacitances and in rated operating potentials ranging from few to several hundred volts.

Optimal Design and Operation of Permanent Irrigation Systems

NASA Astrophysics Data System (ADS)

Oron, Gideon; Walker, Wynn R.

1981-01-01

Solid-set pressurized irrigation system design and operation are studied with optimization techniques to determine the minimum cost distribution system. The principle of the analysis is to divide the irrigation system into subunits in such a manner that the trade-offs among energy, piping, and equipment costs are selected at the minimum cost point. The optimization procedure involves a nonlinear, mixed integer approach capable of achieving a variety of optimal solutions leading to significant conclusions with regard to the design and operation of the system. Factors investigated include field geometry, the effect of the pressure head, consumptive use rates, a smaller flow rate in the pipe system, and outlet (sprinkler or emitter) discharge.

Resistive Wall Modes Identification and Control in RFX-mod low qedge tokamak discharges

NASA Astrophysics Data System (ADS)

Baruzzo, Matteo; Bolzonella, Tommaso; Cavazzana, Roberto; Marchiori, Giuseppe; Marrelli, Lionello; Martin, Piero; Paccagnella, Roberto; Piovesan, Paolo; Piron, Lidia; Soppelsa, Anton; Zanca, Paolo; in, Yongkyoon; Liu, Yueqiang; Okabayashi, Michio; Takechi, Manabu; Villone, Fabio

2011-10-01

In this work the MHD stability of RFX mode tokamak discharges with qedge < 3 will be studied. The target plasma scenario is characterized by a plasma current 100kA

Enhanced electrochemical performance of a ZnO-MnO composite as an anode material for lithium ion batteries.

PubMed

Song, Min Seob; Nahm, Sahn; Cho, Won Il; Lee, Chongmok

2015-09-28

A ZnO-MnO composite was synthesized using a simple solvothermal method combined with a high-temperature treatment. To observe the phase change during the heating process, in situ high-temperature XRD analysis was performed under vacuum conditions. The results indicated that ZnMn2O4 transformed into the ZnO-MnO composite phase starting from 500 °C and that this composite structure was retained until 700 °C. The electrochemical performances of the ZnO-MnO composite electrode were evaluated through galvanostatic discharge-charge tests and cyclic voltammetry analysis. Its initial coulombic efficiency was significantly improved to 68.3% compared to that of ZnMn2O4 at 54.7%. Furthermore, the ZnO-MnO composite exhibited improved cycling performance and enhanced rate capability compared with untreated ZnMn2O4. To clarify the discharge-charge mechanism of the ZnO-MnO composite electrode, the structural changes during the charge and discharge processes were also investigated using ex situ XRD and TEM.

Transitions from near-surface to interior redox upon lithiation in conversion electrode materials.

PubMed

He, Kai; Xin, Huolin L; Zhao, Kejie; Yu, Xiqian; Nordlund, Dennis; Weng, Tsu-Chien; Li, Jing; Jiang, Yi; Cadigan, Christopher A; Richards, Ryan M; Doeff, Marca M; Yang, Xiao-Qing; Stach, Eric A; Li, Ju; Lin, Feng; Su, Dong

2015-02-11

Nanoparticle electrodes in lithium-ion batteries have both near-surface and interior contributions to their redox capacity, each with distinct rate capabilities. Using combined electron microscopy, synchrotron X-ray methods and ab initio calculations, we have investigated the lithiation pathways that occur in NiO electrodes. We find that the near-surface electroactive (Ni(2+) → Ni(0)) sites saturated very quickly, and then encounter unexpected difficulty in propagating the phase transition into the electrode (referred to as a "shrinking-core" mode). However, the interior capacity for Ni(2+) → Ni(0) can be accessed efficiently following the nucleation of lithiation "fingers" that propagate into the sample bulk, but only after a certain incubation time. Our microstructural observations of the transition from a slow shrinking-core mode to a faster lithiation finger mode corroborate with synchrotron characterization of large-format batteries and can be rationalized by stress effects on transport at high-rate discharge. The finite incubation time of the lithiation fingers sets the intrinsic limitation for the rate capability (and thus the power) of NiO for electrochemical energy storage devices. The present work unravels the link between the nanoscale reaction pathways and the C-rate-dependent capacity loss and provides guidance for the further design of battery materials that favors high C-rate charging.

Fast repetition rate (FRR) flasher

DOEpatents

Kolber, Z.; Falkowski, P.

1997-02-11

A fast repetition rate (FRR) flasher is described suitable for high flash photolysis including kinetic chemical and biological analysis. The flasher includes a power supply, a discharge capacitor operably connected to be charged by the power supply, and a flash lamp for producing a series of flashes in response to discharge of the discharge capacitor. A triggering circuit operably connected to the flash lamp initially ionizes the flash lamp. A current switch is operably connected between the flash lamp and the discharge capacitor. The current switch has at least one insulated gate bipolar transistor for switching current that is operable to initiate a controllable discharge of the discharge capacitor through the flash lamp. Control means connected to the current switch for controlling the rate of discharge of the discharge capacitor thereby to effectively keep the flash lamp in an ionized state between successive discharges of the discharge capacitor. Advantageously, the control means is operable to discharge the discharge capacitor at a rate greater than 10,000 Hz and even up to a rate greater than about 250,000 Hz. 14 figs.

Device for generation of pulsed corona discharge

DOEpatents

Gutsol, Alexander F [San Ramon, CA; Fridman, Alexander [Marlton, NJ; Blank, Kenneth [Philadelphia, PA; Korobtsev, Sergey [Moscow, RU; Shiryaevsky, Valery [Moscow, RU; Medvedev, Dmitry [Moscow, RU

2012-05-08

The invention is a method and system for the generation of high voltage, pulsed, periodic corona discharges capable of being used in the presence of conductive liquid droplets. The method and system can be used, for example, in different devices for cleaning of gaseous or liquid media using pulsed corona discharge. Specially designed electrodes and an inductor increase the efficiency of the system, permit the plasma chemical oxidation of detrimental impurities, and increase the range of stable discharge operations in the presence of droplets of water or other conductive liquids in the discharge chamber.

A stage-normalized function for the synthesis of stage-discharge relations for the Colorado River in Grand Canyon, Arizona

USGS Publications Warehouse

Wiele, Stephen M.; Torizzo, Margaret

2003-01-01

A method was developed to construct stage-discharge rating curves for the Colorado River in Grand Canyon, Arizona, using two stage-discharge pairs and a stage-normalized rating curve. Stage-discharge rating curves formulated with the stage-normalized curve method are compared to (1) stage-discharge rating curves for six temporary stage gages and two streamflow-gaging stations developed by combining stage records with modeled unsteady flow; (2) stage-discharge rating curves developed from stage records and discharge measurements at three streamflow-gaging stations; and (3) stages surveyed at known discharges at the Northern Arizona Sand Bar Studies sites. The stage-normalized curve method shows good agreement with field data when the discharges used in the construction of the rating curves are at least 200 cubic meters per second apart. Predictions of stage using the stage-normalized curve method are also compared to predictions of stage from a steady-flow model.

Micro-sized organometallic compound of ferrocene as high-performance anode material for advanced lithium-ion batteries

NASA Astrophysics Data System (ADS)

Liu, Zhen; Feng, Li; Su, Xiaoru; Qin, Chenyang; Zhao, Kun; Hu, Fang; Zhou, Mingjiong; Xia, Yongyao

2018-01-01

An organometallic compound of ferrocene is first investigated as a promising anode for lithium-ion batteries. The electrochemical properties of ferrocene are conducted by galvanostatic charge and discharge. The ferrocene anode exhibits a high reversible capacity and great cycling stability, as well as superior rate capability. The electrochemical reaction of ferrocene is semi-reversible and some metallic Fe remains in the electrode even after delithiation. The metallic Fe formed in electrode and the stable solid electrolyte interphase should be responsible for its excellent electrochemical performance.

High-rate aluminium yolk-shell nanoparticle anode for Li-ion battery with long cycle life and ultrahigh capacity

PubMed Central

Li, Sa; Niu, Junjie; Zhao, Yu Cheng; So, Kang Pyo; Wang, Chao; Wang, Chang An; Li, Ju

2015-01-01

Alloy-type anodes such as silicon and tin are gaining popularity in rechargeable Li-ion batteries, but their rate/cycling capabilities should be improved. Here by making yolk-shell nanocomposite of aluminium core (30 nm in diameter) and TiO2 shell (∼3 nm in thickness), with a tunable interspace, we achieve 10 C charge/discharge rate with reversible capacity exceeding 650 mAh g−1 after 500 cycles, with a 3 mg cm−2 loading. At 1 C, the capacity is approximately 1,200 mAh g−1 after 500 cycles. Our one-pot synthesis route is simple and industrially scalable. This result may reverse the lagging status of aluminium among high-theoretical-capacity anodes. PMID:26243004

Homogeneous growth of TiO2-based nanotubes on nitrogen-doped reduced graphene oxide and its enhanced performance as a Li-ion battery anode.

PubMed

Mehraeen, Shayan; Taşdemir, Adnan; Gürsel, Selmiye Alkan; Yürüm, Alp

2018-06-22

The pursuit of a promising replacement candidate for graphite as a Li-ion battery anode, which can satisfy both engineering criteria and market needs has been the target of researchers for more than two decades. In this work, we have investigated the synergistic effect of nitrogen-doped reduced graphene oxide (NrGO) and nanotubular TiO 2 to achieve high rate capabilities with high discharge capacities through a simple, one-step and scalable method. First, nanotubes of hydrogen titanate were hydrothermally grown on the surface of NrGO sheets, and then converted to a mixed phase of TiO 2 -B and anatase (TB) by thermal annealing. Specific surface area, thermal gravimetric, structural and morphological characterizations were performed on the synthesized product. Electrochemical properties were investigated by cyclic voltammetry and cyclic charge/discharge tests. The prepared anode showed high discharge capacity of 150 mAh g -1 at 1 C current rate after 50 cycles. The promising capacity of synthesized NrGO-TB was attributed to the unique and novel microstructure of NrGO-TB in which long nanotubes of TiO 2 have been grown on the surface of NrGO sheets. Such architecture synergistically reduces the solid-state diffusion distance of Li + and increases the electronic conductivity of the anode.

Status of Pulsed Inductive Thruster Research

NASA Technical Reports Server (NTRS)

Hrbud, Ivana; LaPointe, Michael; Vondra, Robert; Lovberg, Ralph; Dailey, C. Lee; Schafer, Charles (Technical Monitor)

2002-01-01

The TRW Pulsed Inductive Thruster (PIT) is an electromagnetic propulsion system that can provide high thrust efficiency over a wide range of specific impulse values. In its basic form, the PIT consists of a flat spiral coil covered by a thin dielectric plate. A pulsed gas injection nozzle distributes a thin layer of gas propellant across the plate surface at the same time that a pulsed high current discharge is sent through the coil. The rising current creates a time varying magnetic field, which in turn induces a strong azimuthal electric field above the coil. The electric field ionizes the gas propellant and generates an azimuthal current flow in the resulting plasma. The current in the plasma and the current in the coil flow in opposite directions, providing a mutual repulsion that rapidly blows the ionized propellant away from the plate to provide thrust. The thrust and specific impulse can be tailored by adjusting the discharge power, pulse repetition rate, and propellant mass flow, and there is minimal if any erosion due to the electrodeless nature of the discharge. Prior single-shot experiment,; performed with a Diameter diameter version of the PIT at TRW demonstrated specific impulse values between 2,000 seconds and 8,000 seconds, with thruster efficiencies of about 52% for ammonia. This paper outlines current and planned activities to transition the single shot device into a multiple repetition rate thruster capable of supporting NASA strategic enterprise missions.

Homogeneous growth of TiO2-based nanotubes on nitrogen-doped reduced graphene oxide and its enhanced performance as a Li-ion battery anode

NASA Astrophysics Data System (ADS)

Mehraeen, Shayan; Taşdemir, Adnan; Alkan Gürsel, Selmiye; Yürüm, Alp

2018-06-01

The pursuit of a promising replacement candidate for graphite as a Li-ion battery anode, which can satisfy both engineering criteria and market needs has been the target of researchers for more than two decades. In this work, we have investigated the synergistic effect of nitrogen-doped reduced graphene oxide (NrGO) and nanotubular TiO2 to achieve high rate capabilities with high discharge capacities through a simple, one-step and scalable method. First, nanotubes of hydrogen titanate were hydrothermally grown on the surface of NrGO sheets, and then converted to a mixed phase of TiO2-B and anatase (TB) by thermal annealing. Specific surface area, thermal gravimetric, structural and morphological characterizations were performed on the synthesized product. Electrochemical properties were investigated by cyclic voltammetry and cyclic charge/discharge tests. The prepared anode showed high discharge capacity of 150 mAh g‑1 at 1 C current rate after 50 cycles. The promising capacity of synthesized NrGO-TB was attributed to the unique and novel microstructure of NrGO-TB in which long nanotubes of TiO2 have been grown on the surface of NrGO sheets. Such architecture synergistically reduces the solid-state diffusion distance of Li+ and increases the electronic conductivity of the anode.

Rate capability improvement of Co-Ni double hydroxides integrated in cathodically partially exfoliated graphite

NASA Astrophysics Data System (ADS)

Cai, Xiang; Song, Yu; Sun, Zhen; Guo, Di; Liu, Xiao-Xia

2017-10-01

In-situ growing of energy storage materials on graphene-based substrates/current collectors with low defect is a good way to boost electron transport and so enhance rate capability for the obtained electrode. Herein, high-quality graphene-like nanopetals are partially exfoliated from graphite foil (GF) through a facile and fast cathodic process. Three-dimensional porous structure is established for the afforded cathodically-exfoliated graphite foil (CEG), with many graphene-like nanopetals vertically anchoring on the graphite substrate. A hierarchical structure is constructed by the following electrochemical growth of Co-Ni double hydroxide nanopetals on the graphene atop CEG. The double hydroxide in the obtained electrode with the optimized Co2+/Ni2+ molar ratio, Co0.75Ni0.25(OH)2-CEG, displays much improved rate capability and so can deliver a high specific capacitance of 1460 F g-1 at an ultra-high current density of 100 A g-1. An asymmetric device is assembled by using Co0.75Ni0.25(OH)2-CEG as cathode, which demonstrates a high energy density of 31.6 Wh kg-1 at an ultra-high power density of 21.5 kW kg-1, showing the potential of the hierarchical composite electrode for high power application. The device also displays good stability, it can retain more than 90% of its capacitance after 10000 galvanostatic charge-discharge cycles.

On the Stability of NaO2 in Na-O2 Batteries.

PubMed

Liu, Chenjuan; Carboni, Marco; Brant, William R; Pan, Ruijun; Hedman, Jonas; Zhu, Jiefang; Gustafsson, Torbjörn; Younesi, Reza

2018-04-25

Na-O 2 batteries are regarded as promising candidates for energy storage. They have higher energy efficiency, rate capability, and chemical reversibility than Li-O 2 batteries; in addition, sodium is cheaper and more abundant compared to lithium. However, inconsistent observations and instability of discharge products have inhibited the understanding of the working mechanism of this technology. In this work, we have investigated a number of factors that influence the stability of the discharge products. By means of in operando powder X-ray diffraction study, the influence of oxygen, sodium anode, salt, solvent, and carbon cathode were investigated. The Na metal anode and an ether-based solvent are the main factors that lead to the instability and decomposition of NaO 2 in the cell environment. This fundamental insight brings new information on the working mechanism of Na-O 2 batteries.

Experimental test of 200 W Hall thruster with titanium wall

NASA Astrophysics Data System (ADS)

Ding, Yongjie; Sun, Hezhi; Peng, Wuji; Xu, Yu; Wei, Liqiu; Li, Hong; Li, Peng; Su, Hongbo; Yu, Daren

2017-05-01

We designed a 200 W Hall thruster based on the technology of pushing down a magnetic field with two permanent magnetic rings. Boron nitride (BN) is an important insulating wall material for Hall thrusters. The discharge characteristics of the designed Hall thruster were studied by replacing BN with titanium (Ti). Experimental results show that the designed Hall thruster can discharge stably for a long time under a Ti channel. Experiments were performed to determine whether the channel and cathode are electrically connected. When the channel wall and cathode are insulated, the divergence angle of the plume increases, but the performance of the Hall thruster is improved in terms of thrust, specific impulse, anode efficiency, and thrust-to-power ratio. Ti exhibits a powerful antisputtering capability, a low emanation rate of gas, and a large structural strength, making it a potential candidate wall material in the design of low-power Hall thrusters.

Assembly of LiMnPO4 Nanoplates into Microclusters as a High-Performance Cathode in Lithium-Ion Batteries.

PubMed

Wang, Chao; Li, Shiheng; Han, Yuyao; Lu, Zhenda

2017-08-23

A novel structure of a carbon-coated LiMnPO 4 microcluster through emulsion-based self-assembly has been fabricated to yield a high-performance battery cathode. In this rational design, nanosized LiMnPO 4 plates are assembled into microclusters to achieve a dense packing and robust interparticle contact. In addition, the conductive carbon framework wrapping around these clusters functions as a fast electron highway, ensuring the high utilization of the active materials. The designed structure demonstrates enhanced specific capacity and cycling stability in lithium-ion batteries, delivering a discharge capacity of 120 mAh g -1 after 200 cycles at 0.2 C. It also shows a superior rate capability with discharge capacities of 139.7 mAh g -1 at 0.05 C, 131.7 mAh g -1 at 0.1 C, and 99.2 mAh g -1 at 1 C at room temperature.

Gravimetric system using high-speed double switching valves for low liquid flow rates

NASA Astrophysics Data System (ADS)

Cheong, Kar-Hooi; Doihara, Ryouji; Shimada, Takashi; Terao, Yoshiya

2018-07-01

This paper presents a gravimetric system developed to perform the static weighing with flying-start-and-stop (SW-FSS) calibration method at low liquid flow rates using a pair of identical high-speed switching valves as a flow diverter. Features of the gravimetric system comprise three main components: a pair of switching valves that divert the working liquid between two symmetrical flow paths; a weighing vessel equipped with an overflow inner vessel and enclosed in a weighing chamber; and a liquid discharge mechanism comprising a discharge tube and a discharge pump, used with a multi-purpose bin. These are described with an explanation of the design considerations behind each feature. The overflow inner vessel is designed with a notch in its wall and is positioned so that it does not come into contact with the liquid surface of the accumulated liquid in the weighing vessel or the side wall of the weighing vessel to obtain a good repeatability of the interactive effects between the feeding tube and the submerging working liquid, thus ensuring a correct mass reading of the liquid collection. A performance test showed that, in terms of contribution to the overall uncertainty of the standard flow rate, the pair of switching valves is capable of performing SW-FSS satisfactorily with small relative timing errors within %. However, the mass loss due to evaporation is considered a major source of error of the gravimetric system, showing a maximum error of 0.011% under the most evaporative condition tested for the longest liquid collection time of the gravimetric system.

Quantifying the Uncertainty in Discharge Data Using Hydraulic Knowledge and Uncertain Gaugings

NASA Astrophysics Data System (ADS)

Renard, B.; Le Coz, J.; Bonnifait, L.; Branger, F.; Le Boursicaud, R.; Horner, I.; Mansanarez, V.; Lang, M.

2014-12-01

River discharge is a crucial variable for Hydrology: as the output variable of most hydrologic models, it is used for sensitivity analyses, model structure identification, parameter estimation, data assimilation, prediction, etc. A major difficulty stems from the fact that river discharge is not measured continuously. Instead, discharge time series used by hydrologists are usually based on simple stage-discharge relations (rating curves) calibrated using a set of direct stage-discharge measurements (gaugings). In this presentation, we present a Bayesian approach to build such hydrometric rating curves, to estimate the associated uncertainty and to propagate this uncertainty to discharge time series. The three main steps of this approach are described: (1) Hydraulic analysis: identification of the hydraulic controls that govern the stage-discharge relation, identification of the rating curve equation and specification of prior distributions for the rating curve parameters; (2) Rating curve estimation: Bayesian inference of the rating curve parameters, accounting for the individual uncertainties of available gaugings, which often differ according to the discharge measurement procedure and the flow conditions; (3) Uncertainty propagation: quantification of the uncertainty in discharge time series, accounting for both the rating curve uncertainties and the uncertainty of recorded stage values. In addition, we also discuss current research activities, including the treatment of non-univocal stage-discharge relationships (e.g. due to hydraulic hysteresis, vegetation growth, sudden change of the geometry of the section, etc.).

Timeliness in discharge summary dissemination is associated with patients' clinical outcomes.

PubMed

Li, Jordan Y Z; Yong, Tuck Y; Hakendorf, Paul; Ben-Tovim, David; Thompson, Campbell H

2013-02-01

To determine the relation of the readmission rate of general medical patients to either the existence of a discharge summary or the timeliness of its dispatch. This was a retrospective study on discharge summaries of all discharges from the general medical service at a tertiary referral teaching hospital from January 2005 to December 2009. The main outcome measures were readmission rate to hospital within 7 or 28 days of discharge A total of 16 496 patient admissions were included in the analysis. Of these discharges, 3397 (20.6%) patients did not have a summary completed within a week of discharge. There were significant linear trends between patients' readmission rates within 7 (P < 0.001) or 28 days (P < 0.001) and categories reflecting the delay in dispatch of their discharge summaries. The absence of a discharge summary was associated with a 79% increase in the rate of readmission within 7 days [95% confidence interval (CI) 42 to 124% increase; P < 0.001] and a 37% increased rate of readmission within 28 days (95% CI 17 to 61% increase; P < 0.001). If aged less than 80 years, the absence of a discharge summary was associated with a 127% increase in readmission rate within 7 days (95% CI 72 to 202% increase; P < 0.001) and a 55% increase within 28 days (95% CI 25 to 91% increase; P < 0.001) after discharge. Delayed transmission or absence of a discharge summary is associated with readmission of the patient; more so in patients less than 80 years old. If no summary is generated by 7 days after discharge, the rate of readmission within 7 or 28 days after discharge is indistinguishable from no summary being written at all. © 2011 Blackwell Publishing Ltd.

Hierarchical MoO3/SnS2 core-shell nanowires with enhanced electrochemical performance for lithium-ion batteries.

PubMed

Hu, Chenli; Shu, Haibo; Shen, Zihong; Zhao, Tianfeng; Liang, Pei; Chen, Xiaoshuang

2018-06-27

Two-dimensional (2D) tin disulfide (SnS2) is a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity. The main challenges associated with the SnS2 electrodes are the poor cycling stability and low rate capability due to structural degradation in the discharge/charge process. Here, a facile two-step synthesis method is developed to fabricate hierarchical MoO3/SnS2 core-shell nanowires, where ultrathin SnS2 nanosheets are vertically anchored on MoO3 nanobelts to induce a heterointerface. Benefiting from the unique structural and compositional characteristics, the hierarchical MoO3/SnS2 core-shell nanowires exhibit excellent electrochemical performance and deliver a high reversible capacity of 504 mA h g-1 after 100 stable cycles at a current density of 100 mA g-1, which is far superior to the MoO3 and SnS2 electrodes. An analysis of lithiation dynamics based on ab initio molecular dynamics simulations demonstrates that the formation of a hierarchical MoO3/SnS2 core-shell heterostructure can effectively suppress the rapid dissociation of shell-layer SnS2 nanosheets via the interfacial coupling effect and the central MoO3 backbone can trap and support the polysulfide in the discharge/charge process. The results are responsible for the high storage capacity and rate capability of MoO3/SnS2 electrode materials. This work provides a novel design strategy for constructing high-performance electrodes for LIBs.

Carbon-Stabilized Interlayer-Expanded Few-Layer MoSe2 Nanosheets for Sodium Ion Batteries with Enhanced Rate Capability and Cycling Performance.

PubMed

Tang, Yongchao; Zhao, Zongbin; Wang, Yuwei; Dong, Yanfeng; Liu, Yang; Wang, Xuzhen; Qiu, Jieshan

2016-11-30

Sodium ion batteries (SIBs) have been considered as a promising alternative to lithium ion batteries, owing to the abundant reserve and low-cost accessibility of the sodium source. To date, the pursuit of high-performance anode materials remains a great challenge for the SIBs. In this work, carbon-stabilized interlayer-expanded few-layer MoSe 2 nanosheets (MoSe 2 @C) have been fabricated by an oleic acid (OA) functionalized synthesis-polydopamine (PDA) stabilization-carbonization strategy, and their structural, morphological, and electrochemical properties have been carefully characterized and compared with the carbon-free MoSe 2 . When evaluated as anode for sodium ion half batteries, the MoSe 2 @C exhibits a remarkably enhanced rate capability of 367 mA h g -1 at 5 A g -1 , a high reversible discharge capacity of 445 mA h g -1 at 1 A g -1 , and a long-term cycling stability over 100 cycles. To further explore the potential applications, the MoSe 2 @C is assembled into sodium ion full batteries with Na 3 V 2 (PO 4 ) 3 (NVP) as cathode materials, showing an impressively high reversible capacity of 421 mA h g -1 at 0.2 A g -1 after 100 cycles. Such results are primarily attributed to the unique carbon-stabilized interlayer-expanded few-layer MoSe 2 nanosheets structure, which facilitates the permeation of electrolyte into the inner of MoSe 2 nanosheets, promoting charge transfer efficiency among MoSe 2 nanosheets, and accommodating the volume change from discharge-charge cycling.

Novel iron oxide nanotube arrays as high-performance anodes for lithium ion batteries

NASA Astrophysics Data System (ADS)

Zhong, Yuan; Fan, Huiqing; Chang, Ling; Shao, Haibo; Wang, Jianming; Zhang, Jianqing; Cao, Chu-nan

2015-11-01

Nanostructured iron oxides can be promising anode materials for lithium ion batteries (LIBs). However, improvement on the rate capability and/or electrochemical cycling stability of iron oxide anode materials remains a key challenge because of their poor electrical conductivities and large volume expansion during cycling. Herein, the vertically aligned arrays of one-dimensional (1D) iron oxide nanotubes with 5.8 wt% carbon have been fabricated by a novel surfactant-free self-corrosion process and subsequent thermal treatment. The as-fabricated nanotube array electrode delivers a reversible capacity of 932 mAh g-1 after 50 charge-discharge cycles at a current of 0.6 A g-1. The electrode still shows a reversible capacity of 610 mAh g-1 even at a very high rate (8.0 A g-1), demonstrating its prominent rate capability. Furthermore, the nanotube array electrode also exhibits the excellent electrochemical cycling stability with a reversible capacity of 880 mAh g-1 after 500 cycles at a current of 4 A g-1. The nanotube array electrode with superior lithium storage performance reveals the promising potential as a high-performance anode for LIBs.

Vertically aligned carbon nanotube electrodes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Welna, Daniel T.; Qu, Liangti; Taylor, Barney E.; Dai, Liming; Durstock, Michael F.

As portable electronics become more advanced and alternative energy demands become more prevalent, the development of advanced energy storage technologies is becoming ever more critical in today's society. In order to develop higher power and energy density batteries, innovative electrode materials that provide increased storage capacity, greater rate capabilities, and good cyclability must be developed. Nanostructured materials are gaining increased attention because of their potential to mitigate current electrode limitations. Here we report on the use of vertically aligned multi-walled carbon nanotubes (VA-MWNTs) as the active electrode material in lithium-ion batteries. At low specific currents, these VA-MWNTs have shown high reversible specific capacities (up to 782 mAh g -1 at 57 mA g -1). This value is twice that of the theoretical maximum for graphite and ten times more than their non-aligned equivalent. Interestingly, at very high discharge rates, the VA-MWNT electrodes retain a moderate specific capacity due to their aligned nature (166 mAh g -1 at 26 A g -1). These results suggest that VA-MWNTs are good candidates for lithium-ion battery electrodes which require high rate capability and capacity.

Polypyrrole shell@3D-Ni metal core structured electrodes for high-performance supercapacitors.

PubMed

Chen, Gao-Feng; Su, Yu-Zhi; Kuang, Pan-Yong; Liu, Zhao-Qing; Chen, Dao-Yi; Wu, Xu; Li, Nan; Qiao, Shi-Zhang

2015-03-16

Three-dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high-performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D-Ni-core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as-prepared material exhibits a high specific capacitance (726 F g(-1) at a charge/discharge rate of 1 A g(-1)), good rate capability (a decay of 33% in Csp with charge/discharge rates increasing from 1 to 20 A g(-1)), and high cycle stability (only a small decrease of 4.2% in Csp after 1000 cycles at a scan rate of 100 mV s(-1)). Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as-prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg(-1)) and superior long-term cycle ability (only 4.4% and 18.6% loss in Csp after 2000 and 5000 cycles, respectively). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A three-dimensional graphene aerogel containing solvent-free polyaniline fluid for high performance supercapacitors.

PubMed

Gao, Zhaodongfang; Yang, Junwei; Huang, Jing; Xiong, Chuanxi; Yang, Quanling

2017-11-23

Conducting polymer based supercapacitors usually suffer from the difficulty of achieving high specific capacitance and good long-term stability simultaneously. In this communication, a long-chain protonic acid doped solvent-free self-suspended polyaniline (S-PANI) fluid and reduced graphene oxide (RGO) were used to fabricate a three-dimensional RGO/S-PANI aerogel via a simple self-assembled hydrothermal method, which was then applied as a supercapacitor electrode. This 3D RGO/S-PANI composite exhibited a high specific capacitance of up to 480 F g -1 at a current density of 1 A g -1 and 334 F g -1 even at a high discharge rate of 40 A g -1 . An outstanding cycling performance, with 96.14% of the initial capacitance remaining after 10 000 charging/discharging cycles at a rate of 10 A g -1 , was also achieved. Compared with the conventional conducting polymer materials, the 3D RGO/S-PANI composite presented more reliable rate capability and cycling stability. Moreover, S-PANI possesses excellent processability, thereby revealing its enormous potential in large scale production. We anticipate that the solvent-free fluid technique is also applicable to the preparation of other 3D graphene/polymer materials for energy storage.

γ-Fe₂O₃ Nanocrystalline Microspheres with Hybrid Behavior of Battery-Supercapacitor for Superior Lithium Storage.

PubMed

Tian, Lei-Lei; Zhang, Ming-Jian; Wu, Chao; Wei, Yi; Zheng, Jia-Xin; Lin, Ling-Piao; Lu, Jun; Amine, Khalil; Zhuang, Quan-Chao; Pan, Feng

2015-12-02

Maghemite (γ-Fe2O3) nanocrystalline microspheres (MNMs) self-assembled with 52 nm nanocrystals bridged with FeOOH around grain boundaries were formed by solvothermal reaction and thermal oxidation. The unique architecture endows the MNMs with the lithium storage behavior of a hybrid battery-supercapacitor electrode: initial charge capacity of 1060 mAh g(-1) at the 100 mA g(-1) rate, stable cyclic capacity of 1077.9 mAh g(-1) at the same rate after 140 cycles, and rate capability of 538.8 mAh g(-1) at 2400 mA g(-1). This outstanding performance was attributed to the nanocrystal superiority, which shortens the Li(+) diffusion paths. The mechanism of this hybrid anode material was investigated with experimental measurements and structural analysis. The results indicate that at the first discharge, the MNM nanocrystal microsphere, whose structure can buffer the volume change that occurs during lithiation/delithiation, goes through four stages: Li(+) insertion in cation vacancies, spinel-to-rocksalt transformation, Li(+) intercalation of Li(1.75+x)Fe2O3 nanocrystals, and interfacial Li storage around nanocrystal boundaries. Only the latter two stages were reversible at and after the second charging/discharging cycle, exhibiting the hybrid behavior of a battery-supercapacitor with superior lithium storage.

Investigating mixing and emptying for aqueous liquid content from the stomach using a coupled biomechanical-SPH model.

PubMed

Harrison, Simon M; Cleary, Paul W; Sinnott, Matthew D

2018-05-18

The stomach is a critical organ for food digestion but it is not well understood how it operates, either when healthy or when dysfunction occurs. Stomach function depends on the timing and amplitude of wall contractions, the fill level and the type of gastric content. Using a coupled biomechanical-Smoothed Particle Hydrodynamics (B-SPH) model, we investigate how gastric discharge is affected by the contraction behaviour of the stomach wall and the viscosity of the content. The results of the model provide new insights into how the content viscosity and the number of compression waves down the length of the stomach affect the mixing within and the discharge rate of the content exiting from the stomach to the duodenum. This investigation shows that the B-SPH model is capable of simulating complicated stomach behaviour. The rate of gastric emptying is found to increase with a smaller period in between contractile waves and to have a nonlinear relationship with content viscosity. Increased resistance to flow into the duodenum is also shown to reduce the rate of emptying. The degree of gastric mixing is found to be insensitive to changes in the period between contractile waves for fluid with a viscosity of water but to be substantially affected by the viscosity of the gastric content.

Laser processing of thick Li(NiMnCo)O2 electrodes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Rakebrandt, J.-H.; Smyrek, P.; Zheng, Y.; Seifert, H. J.; Pfleging, W.

2017-02-01

Lithium-ion batteries became the most promising types of mobile energy storage devices due to their high gravimetric and volumetric capacity, high cycle life-time, and low self-discharge. Nowadays, the cathode material lithium nickel manganese cobalt oxide (NMC) is one of the most widely used cathode material in commercial lithium-ion batteries due to many advantages such as high energy density (>150 Wh kg-1) on cell level, high power density (650 W kg-1 @ 25 °C and 50 % Depth of Discharge) [1], high specific capacity (163 mAh g-1) [2], high rate capability and good thermal stability in the fully charged state. However, in order to meet the requirements for the increasing demand for rechargeable high energy batteries, nickel-rich NMC electrodes with specific capacities up to 210 mAh g-1 seem to be the next generation cathodes which can reach on cell level desired energy densities higher than 250 Wh kg-1 [3]. Laser-structuring now enables to combine both concepts, high power and high energy lithium-ion batteries. For this purpose, lithium nickel manganese cobalt oxide cathodes were produced via tape casting containing 85-90 wt% of active material with a film thickness of 50-260 μm. The specific capacities were measured using galvanostatic measurements for different types of NMC with varying nickel, manganese and cobalt content at different charging/discharging currents ("C-rates"). An improved lithium-ion diffusion kinetics due to an increased active surface area could be achieved by laser-assisted generating of three dimensional architectures. Cells with unstructured and structured cathodes were compared. Ultrafast laser ablation was used in order to avoid a thermal impact to the material. It was shown that laser structuring of electrode materials leads to a significant improvement in electrochemical performance, especially at high charging and discharging C-rates.

Demonstration of a Fiber Optic Regression Probe in a High-Temperature Flow

NASA Technical Reports Server (NTRS)

Korman, Valentin; Polzin, Kurt

2011-01-01

The capability to provide localized, real-time monitoring of material regression rates in various applications has the potential to provide a new stream of data for development testing of various components and systems, as well as serving as a monitoring tool in flight applications. These applications include, but are not limited to, the regression of a combusting solid fuel surface, the ablation of the throat in a chemical rocket or the heat shield of an aeroshell, and the monitoring of erosion in long-life plasma thrusters. The rate of regression in the first application is very fast, while the second and third are increasingly slower. A recent fundamental sensor development effort has led to a novel regression, erosion, and ablation sensor technology (REAST). The REAST sensor allows for measurement of real-time surface erosion rates at a discrete surface location. The sensor is optical, using two different, co-located fiber-optics to perform the regression measurement. The disparate optical transmission properties of the two fiber-optics makes it possible to measure the regression rate by monitoring the relative light attenuation through the fibers. As the fibers regress along with the parent material in which they are embedded, the relative light intensities through the two fibers changes, providing a measure of the regression rate. The optical nature of the system makes it relatively easy to use in a variety of harsh, high temperature environments, and it is also unaffected by the presence of electric and magnetic fields. In addition, the sensor could be used to perform optical spectroscopy on the light emitted by a process and collected by fibers, giving localized measurements of various properties. The capability to perform an in-situ measurement of material regression rates is useful in addressing a variety of physical issues in various applications. An in-situ measurement allows for real-time data regarding the erosion rates, providing a quick method for empirically anchoring any analysis geared towards lifetime qualification. Erosion rate data over an operating envelope could also be useful in the modeling detailed physical processes. The sensor has been embedded in many regressing media to demonstrate the capabilities in a number of regressing environments. In the present work, sensors were installed in the eroding/regressing throat region of a converging-diverging flow, with the working gas heated to high temperatures by means of a high-pressure arc discharge at steady-state discharge power levels up to 500 kW. The amount of regression observed in each material sample was quantified using a later profilometer, which was compared to the in-situ erosion measurements to demonstrate the efficacy of the measurement technique in very harsh, high-temperature environments.

Computing discharge using the index velocity method

USGS Publications Warehouse

Levesque, Victor A.; Oberg, Kevin A.

2012-01-01

Application of the index velocity method for computing continuous records of discharge has become increasingly common, especially since the introduction of low-cost acoustic Doppler velocity meters (ADVMs) in 1997. Presently (2011), the index velocity method is being used to compute discharge records for approximately 470 gaging stations operated and maintained by the U.S. Geological Survey. The purpose of this report is to document and describe techniques for computing discharge records using the index velocity method. Computing discharge using the index velocity method differs from the traditional stage-discharge method by separating velocity and area into two ratings—the index velocity rating and the stage-area rating. The outputs from each of these ratings, mean channel velocity (V) and cross-sectional area (A), are then multiplied together to compute a discharge. For the index velocity method, V is a function of such parameters as streamwise velocity, stage, cross-stream velocity, and velocity head, and A is a function of stage and cross-section shape. The index velocity method can be used at locations where stage-discharge methods are used, but it is especially appropriate when more than one specific discharge can be measured for a specific stage. After the ADVM is selected, installed, and configured, the stage-area rating and the index velocity rating must be developed. A standard cross section is identified and surveyed in order to develop the stage-area rating. The standard cross section should be surveyed every year for the first 3 years of operation and thereafter at a lesser frequency, depending on the susceptibility of the cross section to change. Periodic measurements of discharge are used to calibrate and validate the index rating for the range of conditions experienced at the gaging station. Data from discharge measurements, ADVMs, and stage sensors are compiled for index-rating analysis. Index ratings are developed by means of regression techniques in which the mean cross-sectional velocity for the standard section is related to the measured index velocity. Most ratings are simple-linear regressions, but more complex ratings may be necessary in some cases. Once the rating is established, validation measurements should be made periodically. Over time, validation measurements may provide additional definition to the rating or result in the creation of a new rating. The computation of discharge is the last step in the index velocity method, and in some ways it is the most straight-forward step. This step differs little from the steps used to compute discharge records for stage-discharge gaging stations. The ratings are entered into database software used for records computation, and continuous records of discharge are computed.

Feasibility of potable water generators to meet vessel numeric ballast water discharge limits.

PubMed

Albert, Ryan J; Viveiros, Edward; Falatko, Debra S; Tamburri, Mario N

2017-07-15

Ballast water is taken on-board vessels into ballast water tanks to maintain vessel draft, buoyancy, and stability. Unmanaged ballast water contains aquatic organisms that, when transported and discharged to non-native waters, may establish as invasive species. Technologies capable of achieving regulatory limits designed to decrease the likelihood of invasion include onboard ballast water management systems. However, to date, the treatment development and manufacturing marketplace is limited to large vessels with substantial ballast requirements. For smaller vessels or vessels with reduced ballast requirements, we evaluated the feasibility of meeting the discharge limits by generating ballast water using onboard potable water generators. Case studies and parametric analyses demonstrated the architectural feasibility of installing potable water generators onboard actual vessels with minimal impacts for most vessel types evaluated. Furthermore, land-based testing of a potable water generator demonstrated capability to meet current numeric discharge limits for living organisms in all size classes. Published by Elsevier Ltd.

Effect of Discharge Rate on Positive Active Material of Lead Carbon Battery for Energy Storage

NASA Astrophysics Data System (ADS)

Chen, Kailun; Liu, Hao; Hu, Chen; Gao, Fei; Yang, Kai; Wang, Hao

2017-10-01

Lead carbon battery has been widespread concern with its excellent performance of charge and discharge under High Rate Part State of Charge (HRPSoC) as well as its cycle performance. In this paper, the cycling performance of lead carbon battery for energy storage was tested by different discharge rate. The effects of different discharge rate on the composition and morphology of positive active materials in the cycle was studied by XRD and SEM. The effect of different discharge rate on the ohmic impedance of lead carbon battery was studied by testing Electrochemical Impedance Spectroscopy with different capacity retention rates. The results show that with the increase of the discharge rate, the content of PbO2 in the positive active material increases, the active substance utilization and the particle size of PbO2 crystal declines, and the ohmic impedance of the battery decreases.

Performance Characterization of a Novel Plasma Thruster to Provide a Revolutionary Operationally Responsive Space Capability with Micro- and Nano-Satellites

DTIC Science & Technology

2011-03-24

and radiation resistance of rare earth permanent magnets for applications such as ion thrusters and high efficiency Stirling Radioisotope Generators...from Electron Transitioning Discharge Current Discharge Power Discharge Voltage Θ Divergence Angle Earths Gravity at Sea Level...Hall effect thruster HIVAC High Voltage Hall Accelerator LEO Low Earth Orbit LDS Laser Displacement System LVDT Linear variable differential

State Firearm Legislation and Nonfatal Firearm Injuries.

PubMed

Simonetti, Joseph A; Rowhani-Rahbar, Ali; Mills, Brianna; Young, Bessie; Rivara, Frederick P

2015-08-01

We investigated whether stricter state-level firearm legislation was associated with lower hospital discharge rates for nonfatal firearm injuries. We estimated discharge rates for hospitalized and emergency department-treated nonfatal firearm injuries in 18 states in 2010 and used negative binomial regression to determine whether strength of state firearm legislation was independently associated with total nonfatal firearm injury discharge rates. We identified 26 744 discharges for nonfatal firearm injuries. The overall age-adjusted discharge rate was 19.0 per 100 000 person-years (state range = 3.3-36.6), including 7.9 and 11.1 discharges per 100 000 for hospitalized and emergency department-treated injuries, respectively. In models adjusting for differences in state sociodemographic characteristics and economic conditions, states in the strictest tertile of legislative strength had lower discharge rates for total (incidence rate ratio [IRR] = 0.60; 95% confidence interval [CI] = 0.44, 0.82), assault-related (IRR = 0.58; 95% CI = 0.34, 0.99), self-inflicted (IRR = 0.18; 95% CI = 0.14, 0.24), and unintentional (IRR = 0.53; 95% CI = 0.34, 0.84) nonfatal firearm injuries. There is significant variation in state-level hospital discharge rates for nonfatal firearm injuries, and stricter state firearm legislation is associated with lower discharge rates for such injuries.

State Firearm Legislation and Nonfatal Firearm Injuries

PubMed Central

Rowhani-Rahbar, Ali; Mills, Brianna; Young, Bessie; Rivara, Frederick P.

2015-01-01

Objectives. We investigated whether stricter state-level firearm legislation was associated with lower hospital discharge rates for nonfatal firearm injuries. Methods. We estimated discharge rates for hospitalized and emergency department–treated nonfatal firearm injuries in 18 states in 2010 and used negative binomial regression to determine whether strength of state firearm legislation was independently associated with total nonfatal firearm injury discharge rates. Results. We identified 26 744 discharges for nonfatal firearm injuries. The overall age-adjusted discharge rate was 19.0 per 100 000 person-years (state range = 3.3–36.6), including 7.9 and 11.1 discharges per 100 000 for hospitalized and emergency department–treated injuries, respectively. In models adjusting for differences in state sociodemographic characteristics and economic conditions, states in the strictest tertile of legislative strength had lower discharge rates for total (incidence rate ratio [IRR] = 0.60; 95% confidence interval [CI] = 0.44, 0.82), assault-related (IRR = 0.58; 95% CI = 0.34, 0.99), self-inflicted (IRR = 0.18; 95% CI = 0.14, 0.24), and unintentional (IRR = 0.53; 95% CI = 0.34, 0.84) nonfatal firearm injuries. Conclusions. There is significant variation in state-level hospital discharge rates for nonfatal firearm injuries, and stricter state firearm legislation is associated with lower discharge rates for such injuries. PMID:26066935

High rate performance of LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} cathode material synthesized by a carbon gel–combustion process for lithium ion batteries

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

Chen, Jian, E-mail: chemcj@126.com; Zhao, Na; Li, Guo-Dong, E-mail: lgd@jlu.edu.cn

2016-01-15

Graphical abstract: The cycling stability of the LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} electrode was investigated at different discharge rates from 5 C to 50 C. - Highlights: • The LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} was prepared via a carbon gel–combustion process. • The sample showed high purity and nanosized particles. • The LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} electrode shows excellent rate capability and cyclic performance. - Abstract: The LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} electrode material was prepared via a carbon gel–combustion process using resorcinol–formaldehyde gel as fuel and nitrate as an oxidizer. The carbon gel process ensures the molecular-level homogeneitymore » of the chemical product. The gas derived from carbon gel separates the raw material particles and restrains the growth of the grains to some extent, and well-crystallized nanosized powders are obtained with calcination at 700 °C for 6 h. As the cathode material for lithium-ion batteries, the discharge capacity of LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} was as high as 175.6 mA h g{sup −1} in the first cycle at 0.5 C, and it could remain 163.0 mA h g{sup −1} within the voltage range of 2.5–4.4 V after 50 cycles. The electrode also showed outstanding rate capacities at high discharge rates such as 30 C and 50 C, suggesting the applications of the material in high power lithium-ion batteries.« less

Trends in hospitalized discharge rates for head injury in Maryland, 1979-86.

PubMed Central

MacKenzie, E J; Edelstein, S L; Flynn, J P

1990-01-01

Hospital discharge data from all acute care hospitals in Maryland were used to examine trends in hospitalized head injury incidence and outcome by severity. From 1979 to 1986, discharge rates increased by 3.4/100,000 per year; the largest percent increase was for more severe injuries. Discharge rates increased the most for adults ages 15-24 and ages 75+ but declined for children ages 0-4. Coinciding with the increase in head injury discharges was a decrease in the hospital case-fatality rate across all severity groups. PMID:2297074

Quantifying the uncertainty in discharge data using hydraulic knowledge and uncertain gaugings: a Bayesian method named BaRatin

NASA Astrophysics Data System (ADS)

Le Coz, Jérôme; Renard, Benjamin; Bonnifait, Laurent; Branger, Flora; Le Boursicaud, Raphaël; Horner, Ivan; Mansanarez, Valentin; Lang, Michel; Vigneau, Sylvain

2015-04-01

River discharge is a crucial variable for Hydrology: as the output variable of most hydrologic models, it is used for sensitivity analyses, model structure identification, parameter estimation, data assimilation, prediction, etc. A major difficulty stems from the fact that river discharge is not measured continuously. Instead, discharge time series used by hydrologists are usually based on simple stage-discharge relations (rating curves) calibrated using a set of direct stage-discharge measurements (gaugings). In this presentation, we present a Bayesian approach (cf. Le Coz et al., 2014) to build such hydrometric rating curves, to estimate the associated uncertainty and to propagate this uncertainty to discharge time series. The three main steps of this approach are described: (1) Hydraulic analysis: identification of the hydraulic controls that govern the stage-discharge relation, identification of the rating curve equation and specification of prior distributions for the rating curve parameters; (2) Rating curve estimation: Bayesian inference of the rating curve parameters, accounting for the individual uncertainties of available gaugings, which often differ according to the discharge measurement procedure and the flow conditions; (3) Uncertainty propagation: quantification of the uncertainty in discharge time series, accounting for both the rating curve uncertainties and the uncertainty of recorded stage values. The rating curve uncertainties combine the parametric uncertainties and the remnant uncertainties that reflect the limited accuracy of the mathematical model used to simulate the physical stage-discharge relation. In addition, we also discuss current research activities, including the treatment of non-univocal stage-discharge relationships (e.g. due to hydraulic hysteresis, vegetation growth, sudden change of the geometry of the section, etc.). An operational version of the BaRatin software and its graphical interface are made available free of charge on request to the authors. J. Le Coz, B. Renard, L. Bonnifait, F. Branger, R. Le Boursicaud (2014). Combining hydraulic knowledge and uncertain gaugings in the estimation of hydrometric rating curves: a Bayesian approach, Journal of Hydrology, 509, 573-587.

Transitions from near-surface to interior redox upon lithiation in conversion electrode materials

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

He, Kai; Xin, Huolin L.; Zhao, Kejie

Nanoparticle electrodes in lithium-ion batteries have both near-surface and interior contributions to their redox capacity, each with distinct rate capabilities. Using combined electron microscopy, synchrotron X-ray methods and ab initio calculations, we have investigated the lithiation pathways that occur in NiO electrodes. We find that the near-surface electroactive (Ni²⁺→Ni⁰) sites saturated very quickly, and then encounter unexpected difficulty in propagating the phase transition into the electrode (referred to as a “shrinking-core” mode). However, the interior capacity for Ni²⁺→Ni⁰ can be accessed efficiently following the nucleation of lithiation “fingers” which propagate into the sample bulk, but only after a certain incubationmore » time. Our microstructural observations of the transition from a slow shrinking-core mode to a faster lithiation finger mode corroborate with synchrotron characterization of large-format batteries, and can be rationalized by stress effects on transport at high-rate discharge. The finite incubation time of the lithiation fingers sets the intrinsic limitation for the rate capability (and thus the power) of NiO for electrochemical energy storage devices. The present work unravels the link between the nanoscale reaction pathways and the C-rate-dependent capacity loss, and provides guidance for the further design of battery materials that favors high C-rate charging.« less

Transitions from near-surface to interior redox upon lithiation in conversion electrode materials

DOE PAGES

He, Kai; Xin, Huolin L.; Zhao, Kejie; ...

2015-01-29

Nanoparticle electrodes in lithium-ion batteries have both near-surface and interior contributions to their redox capacity, each with distinct rate capabilities. Using combined electron microscopy, synchrotron X-ray methods and ab initio calculations, we have investigated the lithiation pathways that occur in NiO electrodes. We find that the near-surface electroactive (Ni²⁺→Ni⁰) sites saturated very quickly, and then encounter unexpected difficulty in propagating the phase transition into the electrode (referred to as a “shrinking-core” mode). However, the interior capacity for Ni²⁺→Ni⁰ can be accessed efficiently following the nucleation of lithiation “fingers” which propagate into the sample bulk, but only after a certain incubationmore » time. Our microstructural observations of the transition from a slow shrinking-core mode to a faster lithiation finger mode corroborate with synchrotron characterization of large-format batteries, and can be rationalized by stress effects on transport at high-rate discharge. The finite incubation time of the lithiation fingers sets the intrinsic limitation for the rate capability (and thus the power) of NiO for electrochemical energy storage devices. The present work unravels the link between the nanoscale reaction pathways and the C-rate-dependent capacity loss, and provides guidance for the further design of battery materials that favors high C-rate charging.« less

Template-free synthesis of vanadium oxides nanobelt arrays as high-rate cathode materials for lithium ion batteries

NASA Astrophysics Data System (ADS)

Qin, Mulan; Liang, Qiang; Pan, Anqiang; Liang, Shuquan; Zhang, Qing; Tang, Yan; Tan, Xiaoping

2014-12-01

A facile hydrothermal route has been developed to fabricate the metastable VO2 (B) ultra-thin nanobelt arrays, which can be converted into V2O5 porous nanobelt arrays after calcinating VO2 (B) in air at 400 °C for 1 h. The influence of hydrothermal time to the crystallinity and morphology of the VO2 phase has been studied. A possible mechanism for the formation of VO2 nanobelt arrays has been proposed in this paper. As a cathode material for lithium ion batteries, the V2O5 nanobelt arrays show excellent rate capability and cycling stability. An initial discharge capacity of 142 mA h g-1 can be delivered at a current density of 50 mA g-1 with almost no capacity fading after 100 cycles. Even at a current density of 1000 mA g-1, they still exhibit the capacity of 130 mA h g-1 and superior capacity retention capability. The excellent electrochemical properties are attributed to the ultra-thin thickness and the porous structures of the nanobelts.

Discharge ratings for control gates at Mississippi River lock and dam 12, Bellevue, Iowa

USGS Publications Warehouse

Heinitz, Albert J.

1986-01-01

The water level of the navigation pools on the Mississippi River are maintained by the operation of tainter and roller gates at the locks and dams. Discharge ratings for the gates on Lock and Dam 12, at Bellevue, Iowa, were developed from current-meter discharge measurements made in the forebays of the gate structures. Methodology is given to accurately compute the gate openings of the tainter gates. Discharge coefficients, in equations that express discharge as a function of tailwater head , forebay head, and height of gate opening, were determined for conditions of submerged-orifice and fee-weir flow. A comparison of the rating discharges to the hydraulic-model rating discharges is given for submerged orifice flow for the tainter and roller gates.

Highly-Stable Li₄Ti₅O12 Anodes Obtained by Atomic-Layer-Deposited Al₂O₃.

PubMed

Yoon, Jae Kook; Nam, Seunghoon; Shim, Hyung Cheoul; Park, Kunwoo; Yoon, Taeho; Park, Hyung Sang; Hyun, Seungmin

2018-05-16

LTO (Li₄Ti₅O 12 ) has been highlighted as anode material for next-generation lithium ion secondary batteries due to advantages such as a high rate capability, excellent cyclic performance, and safety. However, the generation of gases from undesired reactions between the electrode surface and the electrolyte has restricted the application of LTO as a negative electrode in Li-ion batteries in electric vehicles (EVs) and energy storage systems (ESS). As the generation of gases from LTO tends to be accelerated at high temperatures (40⁻60 °C), the thermal stability of LTO should be maintained during battery discharge, especially in EVs. To overcome these technical limitations, a thin layer of Al₂O₃ (~2 nm thickness) was deposited on the LTO electrode surface by atomic layer deposition (ALD), and an electrochemical charge-discharge cycle test was performed at 60 °C. The capacity retention after 500 cycles clearly shows that Al₂O₃-coated LTO outperforms the uncoated one, with a discharge capacity retention of ~98%. TEM and XPS analyses indicate that the surface reactions of Al₂O₃-coated LTO are suppressed, while uncoated LTO undergoes the (111) to (222) phase transformation, as previously reported in the literature.

A performance improvement-based resuscitation programme reduces arrest incidence and increases survival from in-hospital cardiac arrest.

PubMed

Davis, Daniel P; Graham, Patricia G; Husa, Ruchika D; Lawrence, Brenna; Minokadeh, Anushirvan; Altieri, Katherine; Sell, Rebecca E

2015-07-01

Traditional resuscitation training models are inadequate to achieving and maintaining resuscitation competency. This analysis evaluates the effectiveness of a novel, performance improvement-based inpatient resuscitation programme. This was a prospective, before-and-after study conducted in an urban, university-affiliated hospital system. All inpatient adult cardiac arrest victims without an active Do Not Attempt Resuscitation order from July 2005 to June 2012 were included. The advanced resuscitation training (ART) programme was implemented in Spring 2007 and included a unique treatment algorithm constructed around the capabilities of our providers and resuscitation equipment, a training programme with flexible format and content including early recognition concepts, and a comprehensive approach to performance improvement feeding directly back into training. Our inpatient resuscitation registry and electronic patient care record were used to quantify arrest rates and survival-to-hospital discharge before and after ART programme implementation. Multiple logistic regression analysis was used to adjust for age, gender, location of arrest, initial rhythm, and time of day. A total of 556 cardiac arrest victims were included (182 pre- and 374 post-ART). Arrest incidence decreased from 2.7 to 1.2 per 1000 patient discharges in non-ICU inpatient units, with no change in ICU arrest rate. An increase in survival-to-hospital discharge from 21 to 45% (p < 0.01) was observed following ART programme implementation. Adjusted odds ratios for survival-to-discharge (OR 2.2, 95% CI 1.4-3.4) and good neurological outcomes (OR 3.0, 95% CI 1.7-5.3) reflected similar improvements. Arrest-related deaths decreased from 2.1 to 0.5 deaths per 1000 patient discharges in non-ICU areas and from 1.5 to 1.3 deaths per 1000 patient discharges in ICU areas, and overall hospital mortality decreased from 2.2% to 1.8%. Implementation of a novel, performance improvement-based inpatient resuscitation programme was associated with a decrease in the incidence of cardiac arrest and improved clinical outcomes. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Scalable synthesis of Na3V2(PO4)(3)/C porous hollow spheres as a cathode for Na-ion batteries

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

Mao, JF; Luo, C; Gao, T

2015-01-01

Na3V2(PO4)(3) (NVP) has been considered as a very promising cathode material for sodium-ion batteries (SIBs) due to its typical NASICON structure, which provides an open and three dimensional (3D) framework for Na+ migration. However, the low electronic conductivity of NVP limits its rate capability and cycling ability. In this study, carbon coated hollow structured NVP/C composites are synthesized via a template-free and scalable ultrasonic spray pyrolysis process, where the carbon coated NVP particles are uniformly decorated on the inner and outer surfaces of the porous hollow carbon spheres. When evaluated as a cathode material for SIBs, the unique NVP/C porousmore » hollow sphere cathode delivers an initial discharge capacity of 99.2 mA h g(-1) and retains 89.3 mA h g(-1) after 300 charge/discharge cycles with a very low degradation rate of 0.035% per cycle. For comparison, the NVP/C composite, prepared by the traditional sol-gel method, delivers a lower initial discharge capacity of 97.4 mA h g(-1) and decreases significantly to 71.5 mA h g(-1) after 300 cycles. The superior electrochemical performance of NVP/C porous hollow spheres is attributed to their unique porous, hollow and spherical structures, as well as the carbon-coating layer, which provides a high contact area between electrode/electrolyte, high electronic conductivity, and high mechanical strength.« less

PEDOT-PSS coated ZnO/C hierarchical porous nanorods as ultralong-life anode material for lithium ion batteries

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

Xu, Gui-Liang; Li, Yan; Ma, Tianyuan

2015-11-01

ZnO/C hierarchical porous nanorods were synthesized through one-pot wet-chemical reaction followed by thermal calcination. It was found that ZnO/C porous nanorods are composed of numerous nanograins, exhibiting a hierarchical micro/nanostructure. In-situ synchrotron high energy X-ray diffraction study revealed that ZnO/C hierarchical porous nanorods involve a two-step reversible lithiation mechanism during charge/discharge; and part of ZnO and Zn remains at the end of the first discharge and charge process, respectively, leading to a low coulombic efficiency in the initial few cycles. The electrochemical test demonstrated that the reversible capacity and the rate performance of ZnO/C hierarchical porous nanorods anode have beenmore » greatly improved by PEDOT-PSS coating, which could maintain a reversible capacity of 623.94 mA h g(-1) after 1500 cycles at 1 C. Its excellent high rate capability and long cycle stability were attributed to the high electronic conductivity of PEDOT-PSS coating layer and the hierarchical structures of ZnO/C porous nanorods. (C) 2015 Elsevier Ltd. All rights reserved.« less

Recycling bacteria for the synthesis of LiMPO4 (M = Fe, Mn) nanostructures for high-power lithium batteries.

PubMed

Zhou, Yanping; Yang, Dan; Zeng, Yi; Zhou, Yan; Ng, Wun Jern; Yan, Qingyu; Fong, Eileen

2014-10-15

In this work, a novel waste-to-resource strategy to convert waste bacteria into a useful class of cathode materials, lithium metal phosphate (LiMPO4; M = Fe, Mn), is presented. Escherichia coli (E. coli) bacteria used for removing phosphorus contamination from wastewater are harvested and used as precursors for the synthesis of LiMPO4. After annealing, LiFePO4 and LiMnPO4 nanoparticles with dimensions around 20 nm are obtained. These particles are found to be enveloped in a carbon layer with a thickness around 3-5 nm, generated through the decomposition of the organic matter from the bacterial cell cytoplasm. The battery performance for the LiFePO4 is evaluated. A high discharge capacity of 140 mAh g(-1) at 0.1 C with a flat plateau located at around 3.5 V is obtained. In addition, the synthesized particles display excellent stability and rate capabilities. Even under a high C rate of 10 C, a stable discharge capacity of 75.4 mAh g(-1) can still be achieved. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Selection of Wire Electrical Discharge Machining Process Parameters on Stainless Steel AISI Grade-304 using Design of Experiments Approach

NASA Astrophysics Data System (ADS)

Lingadurai, K.; Nagasivamuni, B.; Muthu Kamatchi, M.; Palavesam, J.

2012-06-01

Wire electrical discharge machining (WEDM) is a specialized thermal machining process capable of accurately machining parts of hard materials with complex shapes. Parts having sharp edges that pose difficulties to be machined by the main stream machining processes can be easily machined by WEDM process. Design of Experiments approach (DOE) has been reported in this work for stainless steel AISI grade-304 which is used in cryogenic vessels, evaporators, hospital surgical equipment, marine equipment, fasteners, nuclear vessels, feed water tubing, valves, refrigeration equipment, etc., is machined by WEDM with brass wire electrode. The DOE method is used to formulate the experimental layout, to analyze the effect of each parameter on the machining characteristics, and to predict the optimal choice for each WEDM parameter such as voltage, pulse ON, pulse OFF and wire feed. It is found that these parameters have a significant influence on machining characteristic such as metal removal rate (MRR), kerf width and surface roughness (SR). The analysis of the DOE reveals that, in general the pulse ON time significantly affects the kerf width and the wire feed rate affects SR, while, the input voltage mainly affects the MRR.

Association of heart rate at hospital discharge with mortality and hospitalizations in patients with heart failure.

PubMed

Habal, Marlena V; Liu, Peter P; Austin, Peter C; Ross, Heather J; Newton, Gary E; Wang, Xuesong; Tu, Jack V; Lee, Douglas S

2014-01-01

Heart failure (HF) is associated with a high burden of morbidity and mortality. Hospital discharge is an opportunity for identification of modifiable prognostic factors in the transition to chronic HF. We examined the association of discharge heart rate with 30-day and 1-year mortality and hospitalization outcomes in a cohort of 9097 patients with HF discharged from hospital. Discharge heart rate was categorized into predefined groups: 40 to 60 (n=1333), 61 to 70 (n=2170), 71 to 80 (n=2631), 81 to 90 (n=1700), and >90 bpm (n=1263). There was a significant increase in all-cause 30-day mortality with adjusted odds ratios of 1.59 (95% confidence interval [CI], 1.18-2.14; P=0.003) for discharge heart rates 81 to 90 bpm and 1.56 (95% CI, 1.13-2.16; P=0.007) for heart rates>90 bpm when compared with the reference group (heart rates, 61-70 bpm). Cardiovascular death risk at 30 days was also higher with adjusted odds ratio 1.59 (discharge heart rates, 81-90 bpm; 95% CI, 1.09-2.33; P=0.017) and 1.65 (discharge heart rates, >90 bpm; 95% CI, 1.09-2.48; P=0.017). One-year all-cause mortality (adjusted odds ratio, 1.41; 95% CI, 1.16-1.72; P<0.001) and cardiovascular death (adjusted odds ratio, 1.47; 95% CI, 1.12-1.92; P=0.005) were higher with discharge heart rates>90 bpm when compared with the reference group (heart rates, 40-60 bpm). Readmissions for HF (adjusted hazard ratio, 1.26; 95% CI, 1.04-1.54; P=0.021) and cardiovascular disease (adjusted hazard ratio, 1.29; 95% CI, 1.08-1.54; P=0.004) within 30 days were also higher with discharge heart rates>90 bpm. Higher discharge heart rates were associated with greater risk of all-cause and cardiovascular mortality≤1-year follow-up and an elevated risk of 30-day readmission for HF and cardiovascular disease.

The application of Co-Al-hydrotalcite as a novel additive of positive material for nickel-metal hydride secondary cells

NASA Astrophysics Data System (ADS)

Feng, Zhaobin; Yang, Zhanhong; Yang, Bin; Zhang, Zheng; Xie, Xiaoe

2014-11-01

Co-Al-CO3 layered double hydroxide (LDH) with the different Co/Al molar ration is synthesized by hydrothermal method and investigated as an additive for positive material of the Ni-MH cells. The Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) show the Co-Al-LDH with Co/Al = 4:1 (molar ration) is well-crystallized and hexagon structure. The electrochemical performances of the nickel electrode added with different Co/Al molar ration Co-Al-LDH, the pure nickel electrode and the nickel electrode added with CoO are investigated by the cyclic voltammograms (CV), galvanostatic charge-discharge measurements, and AC electrochemical impedance spectroscopy (EIS). Compared with the pure nickel electrode and the nickel electrode added with CoO, the nickel electrode added with Co/Al = 4:1 (molar ration) Co-Al-LDH has higher discharge capacity and more stable cycling performances. This cell can undergo at least 400 charge-discharge cycles at constant current of 1 C. The discharge capacity of this cell remains about 287 mAh g-1 after the 400th cycle. Meanwhile, compared with the pure electrode, the nickel electrode added with Co/Al = 4:1 (molar ration) Co-Al-LDH possess a higher rate capability to meet the needs of high-storage applications.

Nanosecond plasma-mediated electrosurgery with elongated electrodes

NASA Astrophysics Data System (ADS)

Vankov, Alexander; Palanker, Daniel

2007-06-01

Progress in interventional medicine is associated with the development of more delicate and less invasive surgical procedures, which requires more precise and less traumatic, yet affordable, surgical instruments. Previously we reported on the development of the pulsed electron avalanche knife for dissection of soft tissue in liquid media using the 100 ns plasma-mediated electric discharges applied via a 25 μm disk microelectrode. Cavitation bubbles accompanying explosive vaporization of the liquid medium in front of such a pointed electrode produced a series of craters that did not always merge into a continuous cut. In addition, this approach of surface ablation provided a limited depth of cutting. Application of an elongated electrode capable of cutting with its edge rather than just with its pointed apex faces a problem of nonuniformity of the electric field on a nonspherical electrode. In this article we explore dynamics of the plasma-mediated nanosecond discharges in liquid medium in positive and negative polarities and describe the geometry of an electrode that provides a sufficiently uniform electric field along an extended edge of a surgical probe. A highly enhanced and uniform electric field was obtained on very sharp (2.5 μm) exposed edges of a planar electrode insulated on its flat sides. Uniform ionization and simultaneous vaporization was obtained along the whole edge of such a blade with 100 ns pulses at 4-6 kV. A continuous cutting rate of 1 mm/s in the retina and in soft membranes was achieved at a pulse repetition rate of 100 Hz. The collateral damage zone at the edges of incision did not exceed 80 μm. Negative polarity was found advantageous due to the lower rate of electrode erosion and due to better spatial confinement of the plasma-mediated discharge in liquid.

Comparison of in-hospital versus 30-day mortality assessments for selected medical conditions.

PubMed

Borzecki, Ann M; Christiansen, Cindy L; Chew, Priscilla; Loveland, Susan; Rosen, Amy K

2010-12-01

In-hospital mortality measures such as the Agency for Healthcare Research and Quality (AHRQ) Inpatient Quality Indicators (IQIs) are easily derived using hospital discharge abstracts and publicly available software. However, hospital assessments based on a 30-day postadmission interval might be more accurate given potential differences in facility discharge practices. To compare in-hospital and 30-day mortality rates for 6 medical conditions using the AHRQ IQI software. We used IQI software (v3.1) and 2004-2007 Veterans Health Administration (VA) discharge and Vital Status files to derive 4-year facility-level in-hospital and 30-day observed mortality rates and observed/expected ratios (O/Es) for admissions with a principal diagnosis of acute myocardial infarction, congestive heart failure, stroke, gastrointestinal hemorrhage, hip fracture, and pneumonia. We standardized software-calculated O/Es to the VA population and compared O/Es and outlier status across sites using correlation, observed agreement, and kappas. Of 119 facilities, in-hospital versus 30-day mortality O/E correlations were generally high (median: r = 0.78; range: 0.31-0.86). Examining outlier status, observed agreement was high (median: 84.7%, 80.7%-89.1%). Kappas showed at least moderate agreement (k > 0.40) for all indicators except stroke and hip fracture (k ≤ 0.22). Across indicators, few sites changed from a high to nonoutlier or low outlier, or vice versa (median: 10, range: 7-13). The AHRQ IQI software can be easily adapted to generate 30-day mortality rates. Although 30-day mortality has better face validity as a hospital performance measure than in-hospital mortality, site assessments were similar despite the definition used. Thus, the measure selected for internal benchmarking should primarily depend on the healthcare system's data linkage capabilities.

Probability-based classifications for spatially characterizing the water temperatures and discharge rates of hot springs in the Tatun Volcanic Region, Taiwan.

PubMed

Jang, Cheng-Shin

2015-05-01

Accurately classifying the spatial features of the water temperatures and discharge rates of hot springs is crucial for environmental resources use and management. This study spatially characterized classifications of the water temperatures and discharge rates of hot springs in the Tatun Volcanic Region of Northern Taiwan by using indicator kriging (IK). The water temperatures and discharge rates of the springs were first assigned to high, moderate, and low categories according to the two thresholds of the proposed spring classification criteria. IK was then used to model the occurrence probabilities of the water temperatures and discharge rates of the springs and probabilistically determine their categories. Finally, nine combinations were acquired from the probability-based classifications for the spatial features of the water temperatures and discharge rates of the springs. Moreover, various combinations of spring water features were examined according to seven subzones of spring use in the study region. The research results reveal that probability-based classifications using IK provide practicable insights related to propagating the uncertainty of classifications according to the spatial features of the water temperatures and discharge rates of the springs. The springs in the Beitou (BT), Xingyi Road (XYR), Zhongshanlou (ZSL), and Lengshuikeng (LSK) subzones are suitable for supplying tourism hotels with a sufficient quantity of spring water because they have high or moderate discharge rates. Furthermore, natural hot springs in riverbeds and valleys should be developed in the Dingbeitou (DBT), ZSL, Xiayoukeng (XYK), and Macao (MC) subzones because of low discharge rates and low or moderate water temperatures.

Hospital-based, acute care after ambulatory surgery center discharge.

PubMed

Fox, Justin P; Vashi, Anita A; Ross, Joseph S; Gross, Cary P

2014-05-01

As a measure of quality, ambulatory surgery centers have begun reporting rates of hospital transfer at discharge. This process, however, may underestimate the acute care needs of patients after care. We conducted this study to determine rates and evaluate variation in hospital transfer and hospital-based, acute care within 7 days among patients discharged from ambulatory surgery centers. Using data from the Healthcare Cost and Utilization Project, we identified adult patients who underwent a medical or operative procedure between July 2008 and September 2009 at ambulatory surgery centers in California, Florida, and Nebraska. The primary outcomes were hospital transfer at the time of discharge and hospital-based, acute care (emergency department visits or hospital admissions) within 7-days expressed as the rate per 1,000 discharges. At the ambulatory surgery center level, rates were adjusted for age, sex, and procedure-mix. We studied 3,821,670 patients treated at 1,295 ambulatory surgery centers. At discharge, the hospital transfer rate was 1.1 per 1,000 discharges (95% confidence interval 1.1-1.1). Among patients discharged home, the hospital-based, acute care rate was 31.8 per 1,000 discharges (95% confidence interval 31.6-32.0). Across ambulatory surgery centers, there was little variation in adjusted hospital transfer rates (median = 1.0/1,000 discharges [25th-75th percentile = 1.0-2.0]), whereas substantial variation existed in adjusted, hospital-based, acute care rates (28.0/1,000 [21.0-39.0]). Among adult patients undergoing ambulatory care at surgery centers, hospital transfer at time of discharge from the ambulatory care center is a rare event. In contrast, the rate of need for hospital-based, acute care in the first week afterwards is nearly 30-fold greater, varies across centers, and may be a more meaningful measure for discriminating quality. Published by Mosby, Inc.

An Apparatus for Measuring Rates of Discharge of a Fuel-Injection System

NASA Technical Reports Server (NTRS)

Dutee, Francis J

1941-01-01

A portable apparatus for rapidly determining rates of discharge of a fuel-injection system is described. Satisfactory operation of this apparatus with injection-pump speeds up to 2400 r.p.m was obtained. Rate-of-discharge tests were made with several cam-plunger-valve injection systems with long injection tubes. A check valve designed to reduce secondary discharges was tested. This check valve was operated with injection-pump speeds up to 2400 r.p.m without the occurrence of large secondary discharges.

Test methods and results of the 10-cell bipolar Ni-H2 battery

NASA Technical Reports Server (NTRS)

Cataldo, R.

1983-01-01

Characterization tests were carried out at three charge levels and four discharge levels. The "c' or capacity of the battery is designated at 6.5 ampere-hours. The recharge ampere-hours was the same for all test conditions, 6.5 A-H, regardless of the discharge capacity removed for any particular discharge rate. Less capacity can be removed at higher discharge rates to the same termination voltage, which was 0.50 volts for the weakest (lowest voltage) cell. The general trend of efficiencies increases as the charge rate increases as noted in results of the table included in the handout package. The data also indicate the efficiency increases as the discharge rate decreases. This is true; however, efficiencies at the discharge rates of c and 2c are penalized because these cycles received more overcharge than necessary.

Discharge ratings at gaging stations

USGS Publications Warehouse

Kennedy, E.J.

1984-01-01

A discharge rating is the relation of the discharge at a gaging station to stage and sometimes also to other variables. This chapter of 'Techniques of Water-Resources Investigations' describes the procedures commonly used to develop simple ratings where discharge is related only to stage and the most frequently encountered types of complex ratings where additional factors such as rate of change in stage, water-surface slope, or index velocity are used. Fundamental techniques of logarithmic plotting and the applications of simple storage routing to rating development are demonstrated. Computer applications, especially for handheld programmable calculators, and data handling are stressed.

Dual-protection of a graphene-sulfur composite by a compact graphene skin and an atomic layer deposited oxide coating for a lithium-sulfur battery

NASA Astrophysics Data System (ADS)

Yu, Mingpeng; Wang, Aiji; Tian, Fuyang; Song, Hongquan; Wang, Yinshu; Li, Chun; Hong, Jong-Dal; Shi, Gaoquan

2015-03-01

A reduced graphene oxide (rGO)-sulfur composite aerogel with a compact self-assembled rGO skin was further modified by an atomic layer deposition (ALD) of ZnO or MgO layer, and used as a free-standing electrode material of a lithium-sulfur (Li-S) battery. The rGO skin and ALD-oxide coating worked as natural and artificial barriers to constrain the polysulfides within the cathode region. As a result, the Li-S battery based on this electrode material exhibited superior cycling stability, good rate capability and high coulombic efficiency. Furthermore, ALD-ZnO coating was tested for performance improvement and found to be more effective than ALD-MgO coating. The ZnO modified G-S electrode with 55 wt% sulfur loading delivered a maximum discharge capacity of 998 mA h g-1 at a current density of 0.2 C. A high capacity of 846 mA h g-1 was achieved after charging/discharging for 100 cycles with a coulombic efficiency of over 92%. In the case of using LiNO3 as a shuttle inhibitor, this electrode showed an initial discharge capacity of 796 mA h g-1 and a capacity retention of 81% after 250 cycles at a current density of 1 C with an average coulombic efficiency higher than 99.7%.A reduced graphene oxide (rGO)-sulfur composite aerogel with a compact self-assembled rGO skin was further modified by an atomic layer deposition (ALD) of ZnO or MgO layer, and used as a free-standing electrode material of a lithium-sulfur (Li-S) battery. The rGO skin and ALD-oxide coating worked as natural and artificial barriers to constrain the polysulfides within the cathode region. As a result, the Li-S battery based on this electrode material exhibited superior cycling stability, good rate capability and high coulombic efficiency. Furthermore, ALD-ZnO coating was tested for performance improvement and found to be more effective than ALD-MgO coating. The ZnO modified G-S electrode with 55 wt% sulfur loading delivered a maximum discharge capacity of 998 mA h g-1 at a current density of 0.2 C. A high capacity of 846 mA h g-1 was achieved after charging/discharging for 100 cycles with a coulombic efficiency of over 92%. In the case of using LiNO3 as a shuttle inhibitor, this electrode showed an initial discharge capacity of 796 mA h g-1 and a capacity retention of 81% after 250 cycles at a current density of 1 C with an average coulombic efficiency higher than 99.7%. Electronic supplementary information (ESI) available: Procedures of ALD operation, supplementary figures and details of theoretical simulations. See DOI: 10.1039/c5nr00166h

Measurement of vertical stability metrics in KSTAR

NASA Astrophysics Data System (ADS)

Hahn, Sang-Hee; Humphreys, D. A.; Mueller, D.; Bak, J. G.; Eidietis, N. W.; Kim, H.-S.; Ko, J. S.; Walker, M. L.; Kstar Team

2017-10-01

The paper summarizes results of multi-year ITPA experiments regarding measurement of the vertical stabilization capability of KSTAR discharges, including most recent measurements at the highest achievable elongation (κ 2.0 - 2.1). The measurements of the open-loop growth rate of VDE (γz) and the maximum controllable vertical displacement (ΔZmax) are done by the release-and-catch method. The dynamics of the vertical movement of the plasma is verified by both relevant magnetic reconstructions and non-magnetic diagnostics. The measurements of γz and ΔZmax were done for different plasma currents, βp, internal inductances, elongations and different configurations of the vessel conductors that surround the plasma as the first wall. Effects of control design choice and diagnostics noise are discussed, and comparison with the axisymmetric plasma response model is given for partial accounting for the measured control capability. This work supported by Ministry of Science, ICT, and Future Planning under KSTAR project.

An Evaluation of Selected Extraordinary Floods in the United States Reported by the U.S. Geological Survey and Implications for Future Advancement of Flood Science

USGS Publications Warehouse

Costa, John E.; Jarrett, Robert D.

2008-01-01

Thirty flood peak discharges determine the envelope curve of maximum floods documented in the United States by the U.S. Geological Survey. These floods occurred from 1927 to 1978 and are extraordinary not just in their magnitude, but in their hydraulic and geomorphic characteristics. The reliability of the computed discharge of these extraordinary floods was reviewed and evaluated using current (2007) best practices. Of the 30 flood peak discharges investigated, only 7 were measured at daily streamflow-gaging stations that existed when the flood occurred, and 23 were measured at miscellaneous (ungaged) sites. Methods used to measure these 30 extraordinary flood peak discharges consisted of 21 slope-area measurements, 2 direct current-meter measurements, 1 culvert measurement, 1 rating-curve extension, and 1 interpolation and rating-curve extension. The remaining four peak discharges were measured using combinations of culvert, slope-area, flow-over-road, and contracted-opening measurements. The method of peak discharge determination for one flood is unknown. Changes to peak discharge or rating are recommended for 20 of the 30 flood peak discharges that were evaluated. Nine floods retained published peak discharges, but their ratings were downgraded. For two floods, both peak discharge and rating were corrected and revised. Peak discharges for five floods that are subject to significant uncertainty due to complex field and hydraulic conditions, were re-rated as estimates. This study resulted in 5 of the 30 peak discharges having revised values greater than about 10 percent different from the original published values. Peak discharges were smaller for three floods (North Fork Hubbard Creek, Texas; El Rancho Arroyo, New Mexico; South Fork Wailua River, Hawaii), and two peak discharges were revised upward (Lahontan Reservoir tributary, Nevada; Bronco Creek, Arizona). Two peak discharges were indeterminate because they were concluded to have been debris flows with peak discharges that were estimated by an inappropriate method (slope-area) (Big Creek near Waynesville, North Carolina; Day Creek near Etiwanda, California). Original field notes and records could not be found for three of the floods, however, some data (copies of original materials, records of reviews) were available for two of these floods. A rating was assigned to each of seven peak discharges that had no rating. Errors identified in the reviews include misidentified flow processes, incorrect drainage areas for very small basins, incorrect latitude and longitude, improper field methods, arithmetic mistakes in hand calculations, omission of measured high flows when developing rating curves, and typographical errors. Common problems include use of two-section slope-area measurements, poor site selection, uncertainties in Manning's n-values, inadequate review, lost data files, and insufficient and inadequately described high-water marks. These floods also highlight the extreme difficulty in making indirect discharge measurements following extraordinary floods. Significantly, none of the indirect measurements are rated better than fair, which indicates the need to improve methodology to estimate peak discharge. Highly unsteady flow and resulting transient hydraulic phenomena, two-dimensional flow patterns, debris flows at streamflow-gaging stations, and the possibility of disconnected flow surfaces are examples of unresolved problems not well handled by current indirect discharge methodology. On the basis of a comprehensive review of 50,000 annual peak discharges and miscellaneous floods in California, problems with individual flood peak discharges would be expected to require a revision of discharge or rating curves at a rate no greater than about 0.10 percent of all floods. Many extraordinary floods create complex flow patterns and processes that cannot be adequately documented with quasi-steady, uniform one-dimensional analyses. These floods are most accura

A Multidisciplinary Initiative to Increase Inpatient Discharges Before Noon.

PubMed

Kane, Marlena; Weinacker, Ann; Arthofer, Rudolph; Seay-Morrison, Timothy; Elfman, Wesley; Ramirez, Mark; Ahuja, Neera; Pickham, David; Hereford, James; Welton, Mark

2016-12-01

The aim of this study is to evaluate the effect of 2 hospital-wide interventions on achieving a discharge-before-noon rate of 40%. A multidisciplinary team led by administrative and physician leadership developed a plan to diminish capacity constraints by minimizing late afternoon hospital discharges using 2 patient flow management techniques. The study was a preintervention/postintervention retrospective analysis observing all inpatients discharged across 19 inpatient units in a 484-bed, academic teaching hospital measuring calendar month discharge-before-noon percentage, patient satisfaction, and readmission rates. Patient satisfaction and readmission rates were used as baseline metrics. The discharge-before-noon percentage increased from 14% in the 11-month preintervention period to an average of 24% over the 11-month postintervention period, whereas patient satisfaction scores and readmission rates remained stable. Implementation of the 2 interventions successfully increased the percentage of discharges before noon yet did not achieve the goal of 40%. Patient satisfaction and readmission rates were not negatively impacted by the program.

Relationship of sediment discharge to streamflow

USGS Publications Warehouse

Colby, B.R.

1956-01-01

The relationship between rate of sediment discharge and rate of water discharge at a cross section of a stream is frequently expressed by an average curve. This curve is the sediment rating curve. It has been widely used in the computation of average sediment discharge from water discharge for periods when sediment samples were not collected. This report discusses primarily the applications of sediment rating curves for periods during which at least occasional sediment samples were collected. Because sediment rating curves are of many kinds, the selection of the correct kind for each use is important. Each curve should be carefully prepared. In particular, the correct dependent variable must be used or the slope of the sediment rating curve may be incorrect for computing sediment discharges. Sediment rating curves and their applications were studied for the following gaging stations: 1. Niobrara River near Cody, Nebr. 2. Colorado River near Grand Canyon, Ariz. 3. Rio Grande at San Martial, N. Mex. 4. Rio Puerto near Bernardo, N. Mex. 5. White River near Kadoka, S. Dak. 6. Sandusky River near Fremont, Ohio Except for the Sandusky River and the Rio Puerco, which transport mostly fine sediment, one instantaneous sediment rating curve was prepared for the discharge of suspended sands, at each station, and another for the discharge of sediment finer than 0.082 millimeter. Each curve was studied separately, and by trial-end-error multiple correlation some of the factors that cause scatter from the sediment rating curves were determined. Average velocity at the cross section, Water temperature, and erratic fluctuations in concentration seemed to be the three major factors that caused departures from the sediment rating curves for suspended sands. The concentration of suspended sands varied with about the 2.8 power of the mean velocity for the four sediment, rating curves for suspended sands. The effect of water temperature was not so consistent as that of velocity and theoretically should vary considerably with differences in the size composition of the suspended sands. Scatter from the sediment rating curves for sediments finer than 0.082 millimeter seemed to be caused by changes in supply of these sediments. Some of the scatter could be explained by seasonal variations, by a pattern of change in concentration of fine sediment following a rise, or by source of the runoff as indicated by the measured relative flows of certain tributaries. Daily or instantaneous sediment rating curves adjusted for factors that account for some of the scatter from an average curve often can be used to compute approximate daily, monthly, and annual sediment discharges. Accuracy of the computed sediment discharges should be better than average for streams that transport mostly sands rather than fine sediments and for some ephemeral or intermittent streams, such as Rio Puerco, in semiarid regions. Accuracy of computed sediment discharges can be much improved for many streams by shifting the sediment rating curve on the basis of 2 or 4 measurements of sediment discharge per month. Of 26 annual sediment discharges that were computed by shifting sediment rating curves to either 2 or 4 measured sediment discharges per month, 18 were within I0 percent of the annual-sediment discharges that were computed on the basis of a daily sampling program. Monthly and daily sediment discharges computed from daily or instantaneous sediment rating curves, either shifted or unshifted, were less accurate than similarly computed annual sediment discharges. Even so, the difference in cost between occasional sediment samples and daily samples is so great that the added accuracy from daily sampling may not Justify the added cost. Monthly and annual sediment-rating curves can be applied simply, with adjustments if required, to compute monthly and annual sediment discharges with reasonably good accuracy for gaging stations like the Rio Puerco near Bernardo,

Structural and Electrochemical Study of Hierarchical LiNi(1/3)Co(1/3)Mn(1/3)O2 Cathode Material for Lithium-Ion Batteries.

PubMed

Li, Li; Wang, Lecai; Zhang, Xiaoxiao; Xie, Man; Wu, Feng; Chen, Renjie

2015-10-07

In this study, a facile nanoetching-template route is developed to synthesize porous nanomicrohierarchical LiNi1/3Co1/3Mn1/3O2 microspheres with diameters below 1.5 μm, using porous CoMnO3 binary oxide microspheres as the template. The unique morphology of CoMnO3 template originates from the contraction effect during the oxidative decomposition of Ca0.2Mn0.4Co0.4CO3 precursors and is further improved by selectively removing calcium carbonate with a nanoetching process after calcination. The as-synthesized LiNi1/3Co1/3Mn1/3O2 microsphere, composed of numerous primary particles and pores with size of dozens of nanometers, illustrates a well-assembled porous nanomicrohierarchical structure. When used as the cathode material for lithium-ion batteries, the as-synthesized microspheres exhibit remarkably enhanced electrochemical performances with higher capacity, excellent cycling stability, and better rate capability, compared with the bulk counterpart. Specifically, hierarchical LiNi1/3Co1/3Mn1/3O2 achieves a high discharge capacity of 159.6 mA h g(-1) at 0.2 C with 98.7% capacity retention after 75 cycles and 133.2 mA h g(-1) at 1 C with 90% capacity retention after 100 cycles. A high discharge capacity of 135.5 mA h g(-1) even at a high current of 750 mA g(-1) (5 C) is also achieved. The nanoetching-template method can provide a general approach to improve cycling stability and rate capability of high capacity cathode materials for lithium-ion batteries.

A Novel Uncertainty Framework for Improving Discharge Data Quality Using Hydraulic Modelling.

NASA Astrophysics Data System (ADS)

Mansanarez, V.; Westerberg, I.; Lyon, S. W.; Lam, N.

2017-12-01

Flood risk assessments rely on accurate discharge data records. Establishing a reliable stage-discharge (SD) rating curve for calculating discharge from stage at a gauging station normally takes years of data collection efforts. Estimation of high flows is particularly difficult as high flows occur rarely and are often practically difficult to gauge. Hydraulically-modelled rating curves can be derived based on as few as two concurrent stage-discharge and water-surface slope measurements at different flow conditions. This means that a reliable rating curve can, potentially, be derived much faster than a traditional rating curve based on numerous stage-discharge gaugings. We introduce an uncertainty framework using hydraulic modelling for developing SD rating curves and estimating their uncertainties. The proposed framework incorporates information from both the hydraulic configuration (bed slope, roughness, vegetation) and the information available in the stage-discharge observation data (gaugings). This method provides a direct estimation of the hydraulic configuration (slope, bed roughness and vegetation roughness). Discharge time series are estimated propagating stage records through posterior rating curve results.We applied this novel method to two Swedish hydrometric stations, accounting for uncertainties in the gaugings for the hydraulic model. Results from these applications were compared to discharge measurements and official discharge estimations.Sensitivity analysis was performed. We focused analyses on high-flow uncertainty and the factors that could reduce this uncertainty. In particular, we investigated which data uncertainties were most important, and at what flow conditions the gaugings should preferably be taken.

Effective Discharge and Annual Sediment Yield on Brazos River

NASA Astrophysics Data System (ADS)

Rouhnia, M.; Salehi, M.; Keyvani, A.; Ma, F.; Strom, K. B.; Raphelt, N.

2012-12-01

Geometry of an alluvial river alters dynamically over the time due to the sediment mobilization on the banks and bottom of the river channel in various flow rates. Many researchers tried to define a single representative discharge for these morphological processes such as "bank-full discharge", "effective discharge" and "channel forming discharge". Effective discharge is the flow rate in which, the most sediment load is being carried by water, in a long term period. This project is aimed to develop effective discharge estimates for six gaging stations along the Brazos River from Waco, TX to Rosharon, TX. The project was performed with cooperation of the In-stream Flow Team of the Texas Water Development Board (TWDB). Project objectives are listed as: 1) developing "Flow Duration Curves" for six stations based on mean-daily discharge by downloading the required, additional data from U.S Geological Survey website, 2) developing "Rating Curves" for six gaging stations after sampling and field measurements in three different flow conditions, 3) developing a smooth shaped "Sediment Yield Histogram" with a well distinguished peak as effective discharge. The effective discharge was calculated using two methods of manually and automatic bin selection. The automatic method is based on kernel density approximation. Cross-sectional geometry measurements, particle size distributions and water field samples were processed in the laboratory to obtain the suspended sediment concentration associated with flow rate. Rating curves showed acceptable trends, as the greater flow rate we experienced, the more sediment were carried by water.

Rate Dependent Multi-Mechanism Discharge of Ag 0.50VOP 4·1.8H 2O: Insights from In Situ Energy Dispersive X-ray Diffraction

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

Huie, Matthew M.; Bock, David C.; Zhong, Zhong

Ag 0.50VOPO 4·1.8H 2O (silver vanadium phosphate, SVOP) demonstrates a counterintuitive higher initial loaded voltage under higher discharge current. Energy dispersive X-ray diffraction (EDXRD) from synchrotron radiation was used to create tomographic profiles of cathodes at various depths of discharge for two discharge rates. SVOP displays two reduction mechanisms, reduction of a vanadium center accompanied by lithiation of the structure, or reduction-displacement of a silver cation to form silver metal. In-situ EDXRD provides the opportunity to observe spatially resolved changes to the parent SVOP crystal and formation of Ag 0 during reduction. At a C/170 discharge rate V 5+ reductionmore » is the preferred initial reaction resulting in higher initial loaded voltage. At a discharge rate of C/400 reduction of Ag + with formation of conductive Ag 0 occurs earlier during discharge. Discharge rate also affects the spatial location of reduction products. The faster discharge rate initiates reduction close to the current collector with non-uniform distribution of silver metal resulting in isolated cathode areas. The slower rate develops a more homogenous distribution of reduced SVOP and silver metal. This study illuminates the roles of electronic and ionic conductivity limitations within a cathode at the mesoscale and how they impact the course of reduction processes and loaded voltage.« less

Rate Dependent Multi-Mechanism Discharge of Ag 0.50VOP 4·1.8H 2O: Insights from In Situ Energy Dispersive X-ray Diffraction

DOE PAGES

Huie, Matthew M.; Bock, David C.; Zhong, Zhong; ...

2016-09-01

Ag 0.50VOPO 4·1.8H 2O (silver vanadium phosphate, SVOP) demonstrates a counterintuitive higher initial loaded voltage under higher discharge current. Energy dispersive X-ray diffraction (EDXRD) from synchrotron radiation was used to create tomographic profiles of cathodes at various depths of discharge for two discharge rates. SVOP displays two reduction mechanisms, reduction of a vanadium center accompanied by lithiation of the structure, or reduction-displacement of a silver cation to form silver metal. In-situ EDXRD provides the opportunity to observe spatially resolved changes to the parent SVOP crystal and formation of Ag 0 during reduction. At a C/170 discharge rate V 5+ reductionmore » is the preferred initial reaction resulting in higher initial loaded voltage. At a discharge rate of C/400 reduction of Ag + with formation of conductive Ag 0 occurs earlier during discharge. Discharge rate also affects the spatial location of reduction products. The faster discharge rate initiates reduction close to the current collector with non-uniform distribution of silver metal resulting in isolated cathode areas. The slower rate develops a more homogenous distribution of reduced SVOP and silver metal. This study illuminates the roles of electronic and ionic conductivity limitations within a cathode at the mesoscale and how they impact the course of reduction processes and loaded voltage.« less

Electrochemical synthesis of three-dimensional porous networks of nickel with different micro-nano structures for the fabrication of Ni/MnOx nanocomposites with enhanced supercapacitive performance

NASA Astrophysics Data System (ADS)

Ashassi-Sorkhabi, H.; La'le Badakhshan, P.

2017-10-01

We have electrochemically synthesized 3D-porous Ni/MnOx nanocomposites for supercapacitor applications. 3D porous micro-nanostructured networks of nickel were prepared using hydrogen bubbles as a dynamic template at different deposition potentials and times. The prepared nickel films were used then as 3D-porous substrates for anodic deposition of manganese oxide nanostructures. The effects of deposition potential and time on the structure of the prepared nickel scaffolds and especially on the capacitive behavior of the subsequently fabricated 3D-porous Ni/MnOx nanocomposites were investigated. The results show that the areal capacitance and especially the rate capability of prepared Ni/MnOx nanocomposites have improved with increasing the deposition potential or optimizing the deposition time of nickel films in the nanocomposites. The prepared 3D-porous Ni/MnOx nanocomposite, in which the nickel scaffold has been deposited at the potential of -6 V and duration of 90s, show almost the highest capacitive performance among all other prepared nanocomposites. This prepared nanocomposite, with the loading mass of 1.65 mg cm-2, showed the high areal capacitance of 654 mF cm-2 (396.4 F g-1) at the current density of 0.5 mA cm-2 (0.3 A g-1) in 0.5 M Na2SO4 solution. This nanocomposite also revealed the highest rate capability; the capacitance retention is about 63% (412 mF cm-2) with increasing the discharge rate from 0.5 to 20 mA cm-2, which is almost twice the observed amount of retention when the deposition potential of Ni films was -2 V (31%) or their deposition time was 45 s (34%). In addition, the prepared nanocomposite exhibited an outstanding cycling stability. The capacitance retention was about 98.91% after performing 2000 charge-discharge cycles.

Research, development, and demonstration of lead-acid batteries for electric-vehicle propulsion. Annual report, 1980

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

Not Available

1981-03-01

The first development effort in improving lead-acid batteries fore electric vehicles was the improvement of electric vehicle batteries using flat pasted positive plates and the second was for a tubular long life positive plate. The investigation of 32 component variables based on a flat pasted positive plate configuration is described. The experiment tested 96 - six volt batteries for characterization at 0, 25, and 40/sup 0/C and for cycle life capability at the 3 hour discharge rate with a one cycle, to 80% DOD, per day regime. Four positive paste formulations were selected. Two commercially available microporous separators were usedmore » in conjunction with a layer of 0.076 mm thick glass mat. Two concentrations of battery grade sulfuric acid were included in the test to determine if an increase in concentration would improve the battery capacity sufficient to offset the added weight of the more concentrated solution. Two construction variations, 23 plate elements with outside negative plates and 23 plate elements with outside positive plates, were included. The second development effort was an experiment designed to study the relationship of 32 component variables based on a tubular positive plate configuration. 96-six volt batteries were tested at various discharge rates at 0, 25, and 40/sup 0/C along with cycle life testing at 80% DOD of the 3 hour rate. 75 batteries remain on cycle life testing with 17 batteries having in excess of 365 life cycles. Preliminary conclusions indicate: the tubular positive plate is far more capable of withstanding deep cycles than is the flat pasted plate; as presently designed 40 Whr/kg can not be achieved, since 37.7 Whr/kg was the best tubular data obtained; electrolyte circulation is impaired due to the tight element fit in the container; and a redesign is required to reduce the battery weight which will improve the Whr/kg value. This redesign is complete and new molds have been ordered.« less

Investigation of nanosecond pulsed dielectric barrier discharge using plate-to-plate electrode with asymmetric dielectric arrangement in airflow

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

Qi, Haicheng; School of Physics Science and Technology, Anshan Normal University, Anshan 114005; Fan, Zhihui

Atmospheric pressure dielectric barrier discharge plasma is produced in airflow by applying nanosecond high voltage pulses with peak voltage about 35 kV and rising time about 40 ns on a plate-to-plate electrode arrangement. The effects of airflow rate (0–50 m/s) on the discharge characteristics are investigated under different barrier conditions (the bare anode case and the bare cathode case). For both cases, the breakdown voltage and the time lag increase distinctly and the discharge intensity decreases sharply when the airflow rate increases from 0 to 30 m/s, and then keep almost constant until the airflow rate is further increased to 50 m/s. For the baremore » anode case (the cathode is covered by dielectric plate), the discharge mode transforms gradually from filamentary to diffuse discharge with the increasing airflow rate. While for the bare cathode case, some micro-discharge channels are still excited, though the discharge becomes more diffuse when the airflow rate is higher than 30 m/s. By acquiring the time-resolved images of the discharge, it is proved that it is the primary discharge which becomes diffuse when airflow is introduced and the following two discharges of the same voltage pulse occur principally at the positions where the primary discharge is more intense. And in both cases, the plasma temperatures are reduced, but the degree is different. All the phenomena can be explained mainly by the variation of the space charge distribution when the airflow is introduced into the discharge gap. And it is indicated that the bare anode case has an advantage in obtaining diffuse discharge.« less

Recovery and concordance in a secure forensic psychiatry hospital - the self rated DUNDRUM-3 programme completion and DUNDRUM-4 recovery scales.

PubMed

Davoren, Mary; Hennessy, Sarah; Conway, Catherine; Marrinan, Seamus; Gill, Pauline; Kennedy, Harry G

2015-03-28

Detention in a secure forensic psychiatric hospital may inhibit engagement and recovery. Having validated the clinician rated DUNDRUM-3 (programme completion) and DUNDRUM-4 (recovery) in a forensic hospital, we set out to draft and validate scales measuring the same programme completion and recovery items that patients could use to self-rate. Based on previous work, we hypothesised that self-rating scores might be predictors of objective progress including conditional discharge. We hypothesised also that the difference between patients' and clinicians' ratings of progress in treatment and other factors relevant to readiness for discharge (concordance) would diminish as patients neared discharge. We hypothesised also that this difference in matched scores would predict objective progress including conditional discharge. In a prospective naturalistic observational cohort study in a forensic hospital, we examined whether scores on the self-rated DUNDRUM-3 programme completion and DUNDRUM-4 recovery scales or differences between clinician and patient ratings on the same scales (concordance) would predict moves between levels of therapeutic security and conditional discharge over the next twelve months. Both scales stratified along the recovery pathway of the hospital, but clinician ratings matched the level of therapeutic security more accurately than self ratings. The clinician rated scales predicted moves to less secure units and to more secure units and predicted conditional discharge but the self-rated scores did not. The difference between clinician and self-rated scores (concordance) predicted positive and negative moves and conditional discharge, but this was not always an independent predictor as shown by regression analysis. In regression analysis the DUNDRUM-3 predicted moves to less secure places though the HCR-20 C & R score dominated the model. Moves back to more secure places were predicted by lack of concordance on the DUNDRUM-4. Conditional discharge was predicted predominantly by the DUNDRUM-3. Patients accurately self-rate relative to other patients however their absolute ratings were consistently lower (better) than clinicians' ratings and were less accurate predictors of outcomes including conditional discharge. Quantifying concordance is a useful part of the recovery process and predicts outcomes but self-ratings are not accurate predictors.

Investigation of operating parameters on CO2 splitting by dielectric barrier discharge plasma

NASA Astrophysics Data System (ADS)

Pan, CHEN; Jun, SHEN; Tangchun, RAN; Tao, YANG; Yongxiang, YIN

2017-12-01

Experiments of CO2 splitting by dielectric barrier discharge (DBD) plasma were carried out, and the influence of CO2 flow rate, plasma power, discharge voltage, discharge frequency on CO2 conversion and process energy efficiency were investigated. It was shown that the absolute quantity of CO2 decomposed was only proportional to the amount of conductive electrons across the discharge gap, and the electron amount was proportional to the discharge power; the energy efficiency of CO2 conversion was almost a constant at a lower level, which was limited by CO2 inherent discharge character that determined a constant gap electric field strength. This was the main reason why CO2 conversion rate decreased as the CO2 flow rate increase and process energy efficiency was decreased a little as applied frequency increased. Therefore, one can improve the CO2 conversion by less feed flow rate or larger discharge power in DBD plasma, but the energy efficiency is difficult to improve.

36 CFR 13.1 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-loading weapons do not contain a powder charge; and any other implement capable of discharging a missile into the air or under the water does not contain a missile or similar device within the loading or... designed to discharge missiles into the air or under the water. [71 FR 69333, Nov. 30, 2006, as amended at...

36 CFR 13.1 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-loading weapons do not contain a powder charge; and any other implement capable of discharging a missile into the air or under the water does not contain a missile or similar device within the loading or... designed to discharge missiles into the air or under the water. [71 FR 69333, Nov. 30, 2006, as amended at...

36 CFR 13.1 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-loading weapons do not contain a powder charge; and any other implement capable of discharging a missile into the air or under the water does not contain a missile or similar device within the loading or... designed to discharge missiles into the air or under the water. [71 FR 69333, Nov. 30, 2006, as amended at...

Controlling corrosion rate of Magnesium alloy using powder mixed electrical discharge machining

NASA Astrophysics Data System (ADS)

Razak, M. A.; Rani, A. M. A.; Saad, N. M.; Littlefair, G.; Aliyu, A. A.

2018-04-01

Biomedical implant can be divided into permanent and temporary employment. The duration of a temporary implant applied to children and adult is different due to different bone healing rate among the children and adult. Magnesium and its alloys are compatible for the biodegradable implanting application. Nevertheless, it is difficult to control the degradation rate of magnesium alloy to suit the application on both the children and adult. Powder mixed electrical discharge machining (PM-EDM) method, a modified EDM process, has high capability to improve the EDM process efficiency and machined surface quality. The objective of this paper is to establish a formula to control the degradation rate of magnesium alloy using the PM-EDM method. The different corrosion rate of machined surface is hypothesized to be obtained by having different combinations of PM-EDM operation inputs. PM-EDM experiments are conducted using an opened-loop PM-EDM system and the in-vitro corrosion tests are carried out on the machined surface of each specimen. There are four operation inputs investigated in this study which are zinc powder concentration, peak current, pulse on-time and pulse off-time. The results indicate that zinc powder concentration is significantly affecting the response with 2 g/l of zinc powder concentration obtaining the lowest corrosion rate. The high localized temperature at the cutting zone in spark erosion process causes some of the zinc particles get deposited on the machined surface, hence improving the surface characteristics. The suspended zinc particles in the dielectric fluid have also improve the sparking efficiency and the uniformity of sparks distribution. From the statistical analysis, a formula was developed to control the corrosion rate of magnesium alloy within the range from 0.000183 mm/year to 0.001528 mm/year.

Temporal variability in stage-discharge relationships

NASA Astrophysics Data System (ADS)

Guerrero, José-Luis; Westerberg, Ida K.; Halldin, Sven; Xu, Chong-Yu; Lundin, Lars-Christer

2012-06-01

SummaryAlthough discharge estimations are central for water management and hydropower, there are few studies on the variability and uncertainty of their basis; deriving discharge from stage heights through the use of a rating curve that depends on riverbed geometry. A large fraction of the world's river-discharge stations are presumably located in alluvial channels where riverbed characteristics may change over time because of erosion and sedimentation. This study was conducted to analyse and quantify the dynamic relationship between stage and discharge and to determine to what degree currently used methods are able to account for such variability. The study was carried out for six hydrometric stations in the upper Choluteca River basin, Honduras, where a set of unusually frequent stage-discharge data are available. The temporal variability and the uncertainty of the rating curve and its parameters were analysed through a Monte Carlo (MC) analysis on a moving window of data using the Generalised Likelihood Uncertainty Estimation (GLUE) methodology. Acceptable ranges for the values of the rating-curve parameters were determined from riverbed surveys at the six stations, and the sampling space was constrained according to those ranges, using three-dimensional alpha shapes. Temporal variability was analysed in three ways: (i) with annually updated rating curves (simulating Honduran practices), (ii) a rating curve for each time window, and (iii) a smoothed, continuous dynamic rating curve derived from the MC analysis. The temporal variability of the rating parameters translated into a high rating-curve variability. The variability could turn out as increasing or decreasing trends and/or cyclic behaviour. There was a tendency at all stations to a seasonal variability. The discharge at a given stage could vary by a factor of two or more. The quotient in discharge volumes estimated from dynamic and static rating curves varied between 0.5 and 1.5. The difference between discharge volumes derived from static and dynamic curves was largest for sub-daily ratings but stayed large also for monthly and yearly totals. The relative uncertainty was largest for low flows but it was considerable also for intermediate and large flows. The standard procedure of adjusting rating curves when calculated and observed discharge differ by more than 5% would have required continuously updated rating curves at the studied locations. We believe that these findings can be applicable to many other discharge stations around the globe.

γ-Fe 2 O 3 Nanocrystalline Microspheres with Hybrid Behavior of Battery-Supercapacitor for Superior Lithium Storage

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

Tian, Lei-Lei; Zhang, Ming-Jian; Wu, Chao

Maghemite (γ-Fe2O3) nanocrystalline microspheres (MNMs) self-assembled with 52 nm nanocrystals bridged with FeOOH around grain boundaries were formed by solvothermal reaction and thermal oxidation. The unique architecture endows the MNMs with the lithium storage behavior of a hybrid battery-supercapacitor electrode: initial charge capacity of 1060 mAh g–1 at the 100 mA g–1 rate, stable cyclic capacity of 1077.9 mAh g–1 at the same rate after 140 cycles, and rate capability of 538.8 mAh g–1 at 2400 mA g–1. This outstanding performance was attributed to the nanocrystal superiority, which shortens the Li+ diffusion paths. The mechanism of this hybrid anode materialmore » was investigated with experimental measurements and structural analysis. The results indicate that at the first discharge, the MNM nanocrystal microsphere, whose structure can buffer the volume change that occurs during lithiation/delithiation, goes through four stages: Li+ insertion in cation vacancies, spinel-to-rocksalt transformation, Li+ intercalation of Li1.75+xFe2O3 nanocrystals, and interfacial Li storage around nanocrystal boundaries. Only the latter two stages were reversible at and after the second charging/discharging cycle, exhibiting the hybrid behavior of a battery-supercapacitor with superior lithium storage.« less

High-repetition-rate short-pulse gas discharge.

PubMed

Tulip, J; Seguin, H; Mace, P N

1979-09-01

A high-average-power short-pulse gas discharge is described. This consists of a volume-preionized transverse discharge of the type used in gas lasers driven by a Blumlein energy storage circuit. The Blumlein circuit is fabricated from coaxial cable, is pulse-charged from a high-repetition-rate Marx-bank generator, and is switched by a high-repetition-rate segmented rail gap. The operation of this discharge under conditions typical of rare-gas halide lasers is described. A maximum of 900 pps was obtained, giving a power flow into the discharge of 30 kW.

Novel secondary assembled micro/nano porous spheres ZnCo2O4 with superior electrochemical performances as lithium ion anode material.

PubMed

Liu, Haowen; Hu, Qihong

2018-08-10

In this work, novel secondary assembled micro/nano porous spheres ZnCo 2 O 4 were firstly prepared by combining the hydrothermal method with post-synthesis calcinations. The structure and morphology of the obtained powder were characterized by x-ray powder diffraction and field emission-scanning electron microscopy. As the anode material of lithium-ion half-cells, the as-prepared ZnCo 2 O 4 delivered a very high capacity, extra cycling stability and excellent rate capability. A discharge capacity of 950 mAh g -1 with up to 99.7% retention corresponding to the second cycle at 0.1 C was achieved after 90 cycles, which was an improved cyclability over previous reports. The higher current charge-discharge and electrochemical impedance spectroscopy data indicate that the material's integrity was maintained. Therefore constructing the secondary assembled 3D micro/nano structure is an effective strategy to obtain the superior electrochemical performances.

Ultrafast charge and discharge biscrolled yarn supercapacitors for textiles and microdevices

NASA Astrophysics Data System (ADS)

Lee, Jae Ah; Shin, Min Kyoon; Kim, Shi Hyeong; Cho, Hyun U.; Spinks, Geoffrey M.; Wallace, Gordon G.; Lima, Márcio D.; Lepró, Xavier; Kozlov, Mikhail E.; Baughman, Ray H.; Kim, Seon Jeong

2013-06-01

Flexible, wearable, implantable and easily reconfigurable supercapacitors delivering high energy and power densities are needed for electronic devices. Here we demonstrate weavable, sewable, knottable and braidable yarns that function as high performance electrodes of redox supercapacitors. A novel technology, gradient biscrolling, provides fast-ion-transport yarn in which hundreds of layers of conducting-polymer-infiltrated carbon nanotube sheet are scrolled into ~20 μm diameter yarn. Plying the biscrolled yarn with a metal wire current collector increases power generation capabilities. The volumetric capacitance is high (up to ~179 F cm-3) and the discharge current of the plied yarn supercapacitor linearly increases with voltage scan rate up to ~80 V s-1 and ~20 V s-1 for liquid and solid electrolytes, respectively. The exceptionally high energy and power densities for the complete supercapacitor, and high cycle life that little depends on winding or sewing (92%, 99% after 10,000 cycles, respectively) are important for the applications in electronic textiles.

Nitrate-Melt Synthesized HT-LiCoO2 as a Superior Cathode-Material for Lithium-Ion Batteries

PubMed Central

Sathiya, Mariyappan; Prakash, Annigere S.; Ramesha, Kannadka; Shukla, Ashok K.

2009-01-01

An electrochemically-active high-temperature form of LiCoO2 (HT-LiCoO2) is prepared by thermally decomposing its constituent metal-nitrates at 700 ºC. The synthetic conditions have been optimized to achieve improved performance with the HT-LiCoO2 cathode in Li-ion batteries. For this purpose, the synthesized materials have been characterized by powder X-ray diffraction, scanning electron microscopy, and galvanostatic charge-discharge cycling. Cathodes comprising HT-LiCoO2 exhibit a specific capacity of 140 mAhg-1 with good capacity-retention over several charge-discharge cycles in the voltage range between 3.5 V and 4.2 V, and can sustain improved rate capability in contrast to a cathode constituting LiCoO2 prepared by conventional ceramic method. The nitrate-melt-decomposition method is also found effective for synthesizing Mg-/Al- doped HT-LiCoO2; these also are investigated as cathode materials for Li-ion batteries.

Life test of a xenon hollow cathode for a space plasma contractor

NASA Technical Reports Server (NTRS)

Sarver-Verhey, Timothy R.

1994-01-01

A plasma contacting device using a hollow cathode for plasma production has been baselined for use on the Space Station. This application will require reliable, continuous operation of the cathode at electron emission currents of between 0.75 and 10 A for two years (17,500 hours). In order to validate life-time capability, a hollow cathode, operated in a diode configuration, has been tested for more than 8600 hours of stable discharge operation as of March 30, 1994. This cathode is operated at a steady-state emission current of 12.0 and a fixed xenon flow rate of 4.5 sccm. Discharge voltage and cathode temperature have remained relatively stable at approximately 12.9 V and 1260 C during the test. The test has experienced 7 shutdowns to date. In all instances, the cathode was reignited at about 42 V and resumed stable operation. This test represents the longest demonstration of stable operation of high current (greater than 1A) xenon hollow cathodes reported to date.

High rate capability of a BaTiO3-decorated LiCoO2 cathode prepared via metal organic decomposition

NASA Astrophysics Data System (ADS)

Teranishi, Takashi; Katsuji, Naoto; Yoshikawa, Yumi; Yoneda, Mika; Hayashi, Hidetaka; Kishimoto, Akira; Yoda, Koji; Motobayashi, Hidefumi; Tasaki, Yuzo

2016-10-01

Metal organic decomposition (MOD) using octylic acid salts was applied to synthesize a BaTiO3-LiCoO2 (BT-LC) composite powder. The Ba and Ti octylates were utilized as metal precursors, in an attempt to synthesize homogeneous BT nanoparticles on the LC matrix. The BT-LC composite, having a phase-separated composite structure without any impurity phase, was successfully obtained by optimizing the MOD procedure. The composite prepared using octylate precursors exhibited a sharper distribution and better dispersibility of decorated BT particles. Additionally, the average particle size of the decorated BTs using metal octylate was reduced to 23.3 nm, compared to 44.4 nm from conventional processes using Ba acetate as well as Ti alkoxide as precursors. The composite cathode displayed better cell performance than its conventional counterpart; the discharge capacity of the metal octylate-derived specimen was 55.6 mAh/g at a 50C rate, corresponding to 173% of the capacity of the conventional specimen (32.2 mAh/g). The notable improvement in high rate capability obtained in this study, compared with the conventional route, was attributed to the higher density of the triple junction formed by the BT-LC-electrolyte interface.

Hollow porous bowl-shaped lithium-rich cathode material for lithium-ion batteries with exceptional rate capability and stability

NASA Astrophysics Data System (ADS)

Zhang, Yao; Zhang, Wansen; Shen, Shuiyun; Yan, Xiaohui; Wu, Aiming; Yin, Jiewei; Zhang, Junliang

2018-03-01

Although lithium-rich layered composite cathode materials can meet the requirements of high discharge capacities and energy densities of lithium-ion batteries (LIBs), the drawbacks of encountering structural reconstruction, sharp voltage decay during cycling as well as low packing density still exist, which retard their further commercial development. This paper presents a novel approach to construct hollow porous bowl-shaped Li1.2Mn0.54Ni0.13Co0.13O2 (denoted as HPB-LMNCO) particles, which involves bowl-shaped carbonaceous particles as the predominant template and polyvinylpyrrolidone as an assistant soft template. One crucial step during the synthetic process is the controlled growth of metal ions with specific molar ratios in the bowl-shaped carbonaceous particles, and the key control parameter is the heating rate to ensure the prepared particles own the desired hollow porous bowl-shaped morphology. Of particular note is the desirable architecture which not only inherits the merits of hollow structures but also facilitates the tight particles packing. Owing to these advantages, utilizing this HPB-LMNCO as a cathode material manifests impressive rate capability and exceptional cycling stability at high rates with capacity retention of above 82% over 100 cycles. These results reveal that structural design of cathode materials play a pivotal role in developing high-performance LIBs.

How to increase the efficiency of the electrical discharge method for destruction of nonconductive solid materials

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

Voitenko, N. V., E-mail: tevn@hvd.tpu.ru; Yudin, A. S.; Kuznetsova, N. S.

The paper deals with the relevance of using electrical discharge technology for construction works in the city. The technical capabilities of the installation for the multi-borehole electro-discharge splitting off and destruction of rocks and concrete are described. The ways to increase the efficiency of the electrical discharge method for the destruction of solids are proposed. In order to augment the discharge circuit energy, the energy storage is separated into two individual capacitor batteries. The throttle with the inductance of 28.6 μH is installed in one of the batteries, which increases the duration of the channel energy release to 400 μsmore » and the efficiency of electrical discharge splitting off of concrete.« less

Apparatus for producing voltage and current pulses

DOEpatents

Kirbie, Hugh; Dale, Gregory E.

2010-12-21

An apparatus having one or more modular stages for producing voltage and current pulses. Each module includes a diode charging means to charge a capacitive means that stores energy. One or more charging impedance means are connected to the diode charging means to provide a return current pathway. A solid-state switch discharge means, with current interruption capability, is connected to the capacitive means to discharge stored energy. Finally, a control means is provided to command the switching action of the solid-state switch discharge means.

Visualization of structural evolution and phase distribution of a lithium vanadium oxide (Li 1.1V 3O 8) electrode via an operando and in situ energy dispersive X-ray diffraction technique

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

Zhang, Qing; Bruck, Andrea M.; Bock, David C.

We present Li 1+nV 3O 8 (n = 0–0.2) has been extensively investigated as a cathode material for Li ion batteries because of its superior electrochemical properties including high specific energy and good rate capability. In this paper, a synchrotron based energy dispersive X-ray diffraction (EDXRD) technique was employed to profile the phase transitions and the spatial phase distribution of a Li 1.1V 3O 8 electrode during electrochemical (de)lithiation in situ and operando. As annealing temperature during the preparation of the Li 1.1V 3O 8 material has a strong influence on the morphology and crystallinity, and consequently influences the electrochemicalmore » outcomes of the material, Li 1.1V 3O 8 materials prepared at two different temperatures, 500 and 300°C (LVO500 and LVO300), were employed in this study. The EDXRD spectra of LVO500 and LVO300 cells pre-discharged at C/18, C/40 and C/150 were recorded in situ, and phase localization and relative intensity of the peaks were compared. For cells discharged at the C/18 rate, although α and β phases were distributed uniformly within the LVO500 electrode, they were localized on two sides of the LVO300 electrode. Discharging rates of C/40 and C/150 led to homogeneous β phase formation in both LVO500 and LVO300 electrodes. Furthermore, the phase distribution as a function of position and (de)lithiation extent was mapped operando as the LVO500 cell was (de)lithiated. In conclusion, the operando data indicate that (1) the lithiation reaction initiated from the side of the electrode facing the Li anode and proceeded towards the side facing the steel can, (2) during discharge the phase transformation from a Li-poor to a Li-rich α phase and the formation of a β phase can proceed simultaneously in the electrode after the first formation of a β phase, and (3) the structural evolution occurring during charging is not the reverse of that during discharge and takes place homogenously throughout the electrode.« less

Visualization of structural evolution and phase distribution of a lithium vanadium oxide (Li 1.1V 3O 8) electrode via an operando and in situ energy dispersive X-ray diffraction technique

DOE PAGES

Zhang, Qing; Bruck, Andrea M.; Bock, David C.; ...

2017-05-03

We present Li 1+nV 3O 8 (n = 0–0.2) has been extensively investigated as a cathode material for Li ion batteries because of its superior electrochemical properties including high specific energy and good rate capability. In this paper, a synchrotron based energy dispersive X-ray diffraction (EDXRD) technique was employed to profile the phase transitions and the spatial phase distribution of a Li 1.1V 3O 8 electrode during electrochemical (de)lithiation in situ and operando. As annealing temperature during the preparation of the Li 1.1V 3O 8 material has a strong influence on the morphology and crystallinity, and consequently influences the electrochemicalmore » outcomes of the material, Li 1.1V 3O 8 materials prepared at two different temperatures, 500 and 300°C (LVO500 and LVO300), were employed in this study. The EDXRD spectra of LVO500 and LVO300 cells pre-discharged at C/18, C/40 and C/150 were recorded in situ, and phase localization and relative intensity of the peaks were compared. For cells discharged at the C/18 rate, although α and β phases were distributed uniformly within the LVO500 electrode, they were localized on two sides of the LVO300 electrode. Discharging rates of C/40 and C/150 led to homogeneous β phase formation in both LVO500 and LVO300 electrodes. Furthermore, the phase distribution as a function of position and (de)lithiation extent was mapped operando as the LVO500 cell was (de)lithiated. In conclusion, the operando data indicate that (1) the lithiation reaction initiated from the side of the electrode facing the Li anode and proceeded towards the side facing the steel can, (2) during discharge the phase transformation from a Li-poor to a Li-rich α phase and the formation of a β phase can proceed simultaneously in the electrode after the first formation of a β phase, and (3) the structural evolution occurring during charging is not the reverse of that during discharge and takes place homogenously throughout the electrode.« less

Rehabilitation as "destination triage": a critical examination of discharge planning.

PubMed

Durocher, Evelyne; Gibson, Barbara E; Rappolt, Susan

2017-06-01

In this paper we examine how the intersection of various social and political influences shapes discharge planning and rehabilitation practices in ways that may not meet the espoused aims of rehabilitation programs or the preferences of older adults and their families. Taking a critical bioethics perspective, we used microethnographic case study methods to examine discharge-planning processes in a well-established older adult inpatient rehabilitation setting in Canada. The data included observations of discharge-planning family conferences and semi-structured interviews conducted with older adults facing discharge, their family members and rehabilitation professionals involved in discharge planning. From the time of admission, a contextual push to focus on discharge superseded program aims of providing interventions to increase older adults' functional capabilities. Professionals' primary commitment to safety limited consideration of discharge options and resulted in costly and potentially unnecessary recommendations for 24-hour care. The resulting "rehabilitation" stay was more akin to an extended process of "destination triage" biased towards the promotion of physical safety than optimizing functioning. The resulting reduction of rehabilitation into "destination triage" has significant social, financial and occupational implications for older adults and their families, and broader implications for healthcare services and overarching healthcare systems. Implications for Rehabilitation Current trends promoting consideration of discharge planning from the point of admission and prioritizing physical safety are shifting the focus of rehabilitation away from interventions to maximize recovery of function, which are the stated aims of rehabilitation. Such practices furthermore promote assessments to determine prognosis early in the rehabilitation stay when accurate prognosis is difficult, which can lead to overly conservative recommendations for discharge from rehabilitation services, thus further negating the impact of rehabilitation. Further work is required to examine the social, occupational and functional implications of superseding rehabilitation interventions to maximize capabilities with practices that prioritize safety over quality of life for older adults and their family members.

Improving Posthospital Discharge Telephone Reach Rates Through Prehospital Discharge Face-to-Face Meetings.

PubMed

Vergara, Franz H; Sheridan, Daniel J; Sullivan, Nancy J; Budhathoki, Chakra

The purpose of this study was to determine whether a face-to-face meeting with patients by a telephonic case manager prehospital discharge would result in increased telephone follow-up (TFU) reach rates posthospital discharge. Acute care adult medicine inpatient units. A quasiexperimental design was utilized. Two adult inpatient medicine units were selected as the intervention and comparison groups. The framework of the study is the transitions theory. A convenience sampling technique was used, whereby 88 eligible patients on the intervention unit received face-to-face meetings prehospital discharge whereas 123 patients on the comparison unit received standard care (no face-to-face meetings). Cross-tabulation and chi-square tests were employed to examine the association of face-to-face meeting intervention and TFU reach rates. Implementing brief (<10 min) face-to-face meetings by a telephonic case manager prehospital discharge resulted in a TFU reach rate of 87% on the intervention unit, whereas the comparison unit only had a 58% TFU reach rate (p < .001). Increasing reach rates by a telephonic case manager facilitates communication with more patients posthospital discharge. A brief prehospital discharge face-to-face meeting with patients assisted them to understand the reasons for a posthospital discharge telephone call, identified the best times to call using accurate telephone numbers, and taught patients how best to prepare for the call. In addition, by meeting patients face-to-face, the telephonic case manager was no longer an unknown person on the telephone asking them questions about their medical condition. These factors combined may have significantly helped to increase TFU reach rates.

Hospital discharge rates before and after implementation of a city-wide smoking ban in a Texas city, 2004-2008.

PubMed

Head, Phil; Jackson, Bradford E; Bae, Sejong; Cherry, Debra

2012-01-01

The objective of this study was to examine hospital discharge data on 5 tobacco-related diagnoses before and after implementation of a smoking ban in a small Texas city. We compared hospital discharge rates for 2 years before and 2 years after implementation of the ban in the intervention city with discharge rates during the same time in a similar city with no ban. The discharge rates for blacks and whites combined declined significantly after the ban in the intervention city for acute myocardial infarction (MI) (rate ratio [RR], 0.74; 95% confidence interval [CI], 0.65-0.85) and for stroke or cerebrovascular accident (RR, 0.71; 95% CI, 0.62-0.82); discharge rates in the intervention city also declined significantly for chronic obstructive pulmonary disease (RR, 0.64; 95% CI, 0.54-0.75) and asthma (RR, 0.69; 95% CI, 0.52-0.91) for whites only. Discharge rates for 4 of 5 diagnoses in the control city did not change. Although postban reduction in acute MI is well documented, this is one of the first studies to show a racial disparity in health benefits and a decline in tobacco-related diagnoses other than acute MI after implementation of a city-wide smoking ban.

FIM motor scores for classifying community discharge after inpatient rehabilitation for hip fracture.

PubMed

Wang, Ching-Yi; Graham, James E; Karmarkar, Amol M; Reistetter, Timothy A; Protas, Elizabeth J; Ottenbacher, Kenneth J

2014-06-01

To assess the utility of functional status in classifying patients by discharge setting after inpatient rehabilitation for hip fracture. Retrospective cohort study. A total of 1257 inpatient rehabilitation facilities in the United States. Medicare beneficiaries (N = 117,168) receiving inpatient rehabilitation for hip fracture from 2007 to 2009. Receiver operating characteristic curve analyses to assess the overall discriminatory ability of functional status scores (Functional Independence Measure [FIM] total, FIM cognition, and FIM motor) and to identify the functioning threshold that best differentiates patients by discharge setting. Discharge setting (community versus institutional). Approximately 68% of patients were discharged to the community after inpatient rehabilitation for hip fracture. Receiver operating characteristic curve analyses indicate that discharge FIM motor ratings (area under the curve: 0.84) alone are as effective as a multivariable model (area under the curve: 0.85), including sociodemographic and clinical factors, in discriminating patients discharged to the community from those discharged to an institution. A discharge FIM motor rating of 58 yielded the best balance in sensitivity and specificity for classifying patients by discharge setting. Discharge FIM motor ratings demonstrated good discriminatory ability for classifying discharge setting. An FIM motor rating of 58 may serve as a clinical tool to guide treatment plans and/or as additional information in complex discharge planning decisions for patients with hip fracture. Copyright © 2014 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Can hydraulic-modelled rating curves reduce uncertainty in high flow data?

NASA Astrophysics Data System (ADS)

Westerberg, Ida; Lam, Norris; Lyon, Steve W.

2017-04-01

Flood risk assessments rely on accurate discharge data records. Establishing a reliable rating curve for calculating discharge from stage at a gauging station normally takes years of data collection efforts. Estimation of high flows is particularly difficult as high flows occur rarely and are often practically difficult to gauge. Hydraulically-modelled rating curves can be derived based on as few as two concurrent stage-discharge and water-surface slope measurements at different flow conditions. This means that a reliable rating curve can, potentially, be derived much faster than a traditional rating curve based on numerous stage-discharge gaugings. In this study we compared the uncertainty in discharge data that resulted from these two rating curve modelling approaches. We applied both methods to a Swedish catchment, accounting for uncertainties in the stage-discharge gauging and water-surface slope data for the hydraulic model and in the stage-discharge gauging data and rating-curve parameters for the traditional method. We focused our analyses on high-flow uncertainty and the factors that could reduce this uncertainty. In particular, we investigated which data uncertainties were most important, and at what flow conditions the gaugings should preferably be taken. First results show that the hydraulically-modelled rating curves were more sensitive to uncertainties in the calibration measurements of discharge than water surface slope. The uncertainty of the hydraulically-modelled rating curves were lowest within the range of the three calibration stage-discharge gaugings (i.e. between median and two-times median flow) whereas uncertainties were higher outside of this range. For instance, at the highest observed stage of the 24-year stage record, the 90% uncertainty band was -15% to +40% of the official rating curve. Additional gaugings at high flows (i.e. four to five times median flow) would likely substantially reduce those uncertainties. These first results show the potential of the hydraulically-modelled curves, particularly where the calibration gaugings are of high quality and cover a wide range of flow conditions.

An improved scan laser with a VO2 programmable mirror

NASA Astrophysics Data System (ADS)

Chivian, J. S.; Scott, M. W.; Case, W. E.; Krasutsky, N. J.

1985-04-01

A 10.6-microns scan laser has been constructed and operated with an off-axis cathode ray tube, high reflectance multilayer thin-film structures, and a tapered plasma discharge tube. Equations are given for the switching time of a high-reflectance spot on the VO2 and for the relation of scan laser output power to cavity geometry, cavity losses, and the gain of the active CO2 medium. A scan capability of 2100 easily resolvable directions was demonstrated, and sequential and randomly addressed spot rates of 100,000/sec were achieved. The equations relating output power and cavity mode size were experimentally verified using a nonscanned beam.

A new concept for high-cycle-life LEO: Rechargeable MnO2-hydrogen

NASA Technical Reports Server (NTRS)

Appleby, A. J.; Dhar, H. P.; Kim, Y. J.; Murphy, O. J.

1989-01-01

The nickel-hydrogen secondary battery system, developed in the early 1970s, has become the system of choice for geostationary earth orbit (GEO) applications. However, for low earth orbit (LEO) satellites with long expected lifetimes the nickel positive limits performance. This requires derating of the cell to achieve very long cycle life. A new system, rechargeable MnO2-Hydrogen, which does not require derating, is described here. For LEO applications, it promises to have longer cycle life, high rate capability, a higher effective energy density, and much lower self-discharge behavior than those of the nickel-hydrogen system.

Intercalation Pseudocapacitance of Exfoliated Molybdenum Disulfide for Ultrafast Energy Storage

DOE PAGES

Yoo, Hyun Deog; Li, Yifei; Liang, Yanliang; ...

2016-05-23

In this study, we report intercalation pseudocapacitance of 250 F g -1 for exfoliated molybdenum disulfide (MoS 2) in non-aqueous electrolytes that contain lithium ions. The exfoliated MoS 2 shows surface-limited reaction kinetics with high rate capability up to 3 min of charge or discharge. The intercalation pseudocapacitance originates from the extremely fast kinetics due to the enhanced ionic and electronic transport enabled by the slightly expanded layer structure as well as the metallic 1T-phase. The exfoliated MoS 2 could be also used in a Li-Mg-ion hybrid capacitor, which shows full cell specific capacitance of 240 F g -1.

A Spinel-integrated P2-type Layered Composite: High-rate Cathode for Sodium-ion Batteries

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

Zheng, Jianming; Yan, Pengfei; Kan, Wang Hay

2016-01-14

Sodium-ion batteries (SIB) are being intensively investigated, owing to the natural abundance and low cost of Na resources. However, the SIBs still suffer from poor rate capability due to the large ionic radius of Na+ ion and the significant kinetic barrier to Na+-ion transport. Here, we present an Fd-3m spinel-integrated P2-type layered composite (P2 + Fd-3m) material as a high-rate cathode for SIBs. The P2 + Fd-3m composite material Na0.50Ni1/6Co1/6Mn2/3O2 shows significantly enhanced discharge capacity, energy density, and rate capability as compared to the pure P2-type counterpart. The composite delivers a high capacity of 85 mA h g-1 when dischargingmore » at a very high current density of 1500 mA g-1 (10C rate) between 2.0 and 4.5 V, validating it as a promising cathode candidate for high-power SIBs. The superior performance is ascribed to the improved kinetics in the presence of the integrated-spinel phase, which facilitates fast electron transport to coordinate with the timely Na+-ion insertion/extraction. The findings of this work also shed light on the importance of developing lattice doping, surface coating, and electrolyte additives to further improve the structural and interfacial stability of P2-type cathode materials and fully realize their practical applications in sodium-ion batteries.« less

Sphere-Shaped Hierarchical Cathode with Enhanced Growth of Nanocrystal Planes for High-Rate and Cycling-Stable Li-Ion Batteries

DOE PAGES

Zhang, Linjing; Li, Ning; Wu, Borong; ...

2015-01-14

High-energy and high-power Li-ion batteries have been intensively pursued as power sources in electronic vehicles and renewable energy storage systems in smart grids. With this purpose, developing high-performance cathode materials is urgently needed. Here we report an easy and versatile strategy to fabricate high-rate and cycling-stable hierarchical sphered cathode Li 1.2Ni 0.13Mn 0.54Co 0.13O 2, by using an ionic interfusion method. The sphere-shaped hierarchical cathode is assembled with primary nanoplates with enhanced growth of nanocrystal planes in favor of Li+ intercalation/deintercalation, such as (010), (100), and (110) planes. This material with such unique structural features exhibits outstanding rate capability, cyclability,more » and high discharge capacities, achieving around 70% (175 mAh g–1) of the capacity at 0.1 C rate within about 2.1 min of ultrafast charging. Such cathode is feasible to construct high-energy and high-power Li-ion batteries.« less

Sphere-shaped hierarchical cathode with enhanced growth of nanocrystal planes for high-rate and cycling-stable li-ion batteries.

PubMed

Zhang, Linjing; Li, Ning; Wu, Borong; Xu, Hongliang; Wang, Lei; Yang, Xiao-Qing; Wu, Feng

2015-01-14

High-energy and high-power Li-ion batteries have been intensively pursued as power sources in electronic vehicles and renewable energy storage systems in smart grids. With this purpose, developing high-performance cathode materials is urgently needed. Here we report an easy and versatile strategy to fabricate high-rate and cycling-stable hierarchical sphered cathode Li(1.2)Ni(0.13)Mn(0.54)Co(0.13)O2, by using an ionic interfusion method. The sphere-shaped hierarchical cathode is assembled with primary nanoplates with enhanced growth of nanocrystal planes in favor of Li(+) intercalation/deintercalation, such as (010), (100), and (110) planes. This material with such unique structural features exhibits outstanding rate capability, cyclability, and high discharge capacities, achieving around 70% (175 mAh g(-1)) of the capacity at 0.1 C rate within about 2.1 min of ultrafast charging. Such cathode is feasible to construct high-energy and high-power Li-ion batteries.

Over atmospheric pressure flowing afterglow

NASA Astrophysics Data System (ADS)

Ganciu, Mihai; Orphal, Johannes; Vervloet, Michel; Pointu, Anne-Marie; Touzeau, Michel

2002-10-01

A Tabletop discharge * created above atmospheric pressure in a N2 gas flow, uses some 10 kV very fast high voltage pulses applied between needle electrodes with some 10 kHz repetition rate. It is followed by a post-discharge, in a plastic tube with 6-mm internal diameter. Adjusting the flow and the repetition rate, the post-discharge exhibits a surprisingly long size, 9-10 m, as shown by the tube fluorescence. Preliminary spectroscopic measurements demonstrate that fluorescence is due to internal gas excited molecules (CN and NH) that are locally created by active species interaction with organic impurities. The discharge emission spectrum evidences a high nitrogen atom production rate, much higher than attainable rate with a Dielectric Barrier Discharge with same applied voltage pulses. For small air quantities added in the post-discharge, spectrum exhibits rich UV range corresponding to NO excited states. Further studies will be devoted to the post-discharge kinetics and to possible applications to medical sterilization. *M. Ganciu, private communication

Performance of Wide Operating Temperature Range Electrolytes in Quallion Prototype Li-Ion Cells

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Tomcsi, M. R.; Nagata, M.; Visco, V.; Tsukamoto, H.

2010-01-01

For a number of applications, there is a continued interest in the development of rechargeable lithium-based batteries that can effectively operate over a wide temperature range (i.e., -40 to +70 deg C). These applications include powering future planetary rovers for NASA, enabling the next generation of automotive batteries for DOE, and supporting many DOD applications. Li-ion technology has been demonstrated to have good performance over a reasonably wide temperature range with many systems; however, there is still a desire to improve the low temperature rate capacity as well as the high temperature resilience. In the current study, we would like to present recent results obtained with prototype Li-Ion cells (manufactured by Quallion, LLC) which include various wide operating temperature range electrolytes developed by both JPL and Quallion. To demonstrate the viability of the technology, a number of performance tests were carried out, including: (a) discharge rate characterization over a wide temperature range (down to -60 deg C) using various rates (up to 20C rates), (b) discharge rate characterization at low temperatures with low temperature charging, (c) variable temperature cycling over a wide temperature range (-40 to +70 deg C), and (d) cycling at high temperature (50 deg C). As will be discussed, impressive rate capability was observed at low temperatures with many systems, as well as good resilience to high temperature cycling. To augment the performance testing on the prototype cells, a number of experimental three electrodes cells were fabricated (including Li reference electrodes) to allow the determination of the lithium kinetics of the respective electrodes and interfacial properties as a function of temperatures.

Communication at the interface between hospitals and primary care - a general practice audit of hospital discharge summaries.

PubMed

Belleli, Esther; Naccarella, Lucio; Pirotta, Marie

2013-12-01

Timeliness and quality of hospital discharge summaries are crucial for patient safety and efficient health service provision after discharge. We audited receipt rates, timeliness and the quality of discharge summaries for 49 admissions among 38 patients in an urban general practice. For missing discharge summaries, a hospital medical record search was performed. Discharge summaries were received for 92% of identified admissions; 73% were received within three days and 55% before the first post-discharge visit to the general practitioner (GP). Administrative information and clinical content, including diagnosis, treatment and follow-up plans, were well reported. However, information regarding tests, referrals and discharge medication was often missing; 57% of summaries were entirely typed and 13% had legibility issues. Completion rates were good but utility was compromised by delays, content omissions and formatting. Digital searching enables extraction of information from rich existing datasets contained in GP records for accurate measurement of discharge summary receipt rate and timing.

[Removal of SO2 from flue gas by water vapor DC corona discharge].

PubMed

Sun, Ming; Wu, Yan

2006-07-01

The influence of several factors on removal rate of SO2 from flue gas in unsaturated water vapor DC corona discharge was researched. Furthermore, the experiments of the removal rate of SO2 in pulsed discharge increased by water vapor DC corona discharge plasma were conducted. The experiment system is supplied with multi-nozzle-plate electrodes and the flow of simulated flue gas is under 70 m3/h. The results show that removal rate of SO2 can be improved by increasing the concentration of water vapor, intensity of electric field or decreasing flow of simulated flue gas. In unsaturated water vapor DC corona discharge, removal rate of SO2 can be improved by 10%, when NH3 is added as NH3 and SO2 is in a mole ratio of two to one, it can reach 60%. The removal rate of SO2 can be increased by 5% in pulsed corona discharge and reach above 90%.

Some Factors Affecting the Reproducibility of Penetration and the Cut-Off of Oil Sprays for Fuel-injection Engines

NASA Technical Reports Server (NTRS)

Beardsley, E G

1928-01-01

This investigation was undertaken at the Langley Memorial Aeronautical Laboratory in connection with a general research on fuel-injection for aircraft. The purpose of the investigation was to determine the factors controlling the reproducibility of spray penetration and secondary discharges after cut-off. The development of single sprays from automatic injection valves was recorded by means of special high-speed photographic apparatus capable of taking 25 consecutive pictures of the moving spray at a rate of 4,000 per second. The effect of two types of injection valves, injection-valve tube length, initial pressure in the injection-valve tube, speed of the injection control mechanism, and time of spray cut-off, on the reproducibility of spray penetration, and on secondary discharges were investigated. It was found that neither type of injection valve materially affected spray reproducibility. The initial pressure in the injection-valve tube controlled the reproducibility of spray penetrations. An increase in the initial pressure or in the length of the injection-valve tube slightly increased the spray penetration within the limits of this investigation. The speed of the injection-control mechanism did not affect the penetration. Analysis of the results indicates that secondary discharges were caused in this apparatus by pressure waves initiated by the rapid opening of the cut-off valve. The secondary discharges were eliminated in this investigation by increasing the length of the injection-valve tube. (author)

Radio Emissions from Electrical Activity in Martian Dust Storms

NASA Astrophysics Data System (ADS)

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

2017-12-01

Dust storms on Mars are predicted to be capable of producing electrostatic fields and discharges, even larger than those in dust storms on Earth. There are three key elements in the characterization of Martian electrostatic discharges: dependence on Martian environmental conditions, event rate, and the strength of the generated electric fields. The detection and characterization of electric activity in Martian dust storms has important implications for habitability, and preparations for human exploration of the red planet. Furthermore, electrostatic discharges may be linked to local chemistry and plays an important role in the predicted global electrical circuit. Because of the continuous Mars telecommunication needs of NASA's Mars-based assets, the Deep Space Network (DSN) is the only facility in the world that combines long term, high cadence, observing opportunities with large sensitive telescopes, making it a unique asset worldwide in searching for and characterizing electrostatic activity from large scale convective dust storms at Mars. We will describe a newly inaugurated program at NASA's Madrid Deep Space Communication Complex to carry out a long-term monitoring campaign to search for and characterize the entire Mars hemisphere for powerful discharges during routine tracking of spacecraft at Mars on an entirely non-interfering basis. The ground-based detections will also have important implications for the design of a future instrument that could make similar in-situ measurements from orbit or from the surface of Mars, with far greater sensitivity and duty cycle, opening up a new window in our understanding of the Martian environment.

High grain boundary density Li{sub 4}Ti{sub 5}O{sub 12}/anatase-TiO{sub 2} nanocomposites as anode material for Li-ion batteries

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

Stenina, I.A.; Kulova, T.L.; Skundin, A.M.

2016-03-15

Highlights: • Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites with high grain boundary density were synthesized. • {sup 7}Li NMR and impedance spectroscopy shows high Li-ion mobility in nanocomposites. • The shape of charge/discharge curves changes for nanocomposites. • Influence of particle size on cycling performance of lithium titanates was shown. • Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposite exhibits good cycling performance and rate capability. - Abstract: Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites are synthesized by a sol-gel method. The size of Li{sub 4}Ti{sub 5}O{sub 12} and TiO{sub 2} particles is of 4–5 and 7–10 nm, respectively. The obtained materials aremore » characterized by XRD, SEM, HRTEM and BET. Ion mobility of the composites and their performance as anode materials for lithium-ion batteries are studied. According to the conductivity and {sup 7}Li NMR data, Li{sup +} mobility is much higher in the Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites as compared with that in pure Li{sub 4}Ti{sub 5}O{sub 12}. For Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} nanocomposites, marked changes in the charge–discharge curves are observed; charge–discharge rate and effective capacity at a high cycling rate are shown to increase. During the first cycle, charge capacity of these materials surpasses the theoretical capacity of Li{sub 4}Ti{sub 5}O{sub 12}. However, this parameter decreases sharply with cycling, whereas the discharge capacity remains almost unchanged. This phenomenon is attributed to the solid electrolyte interphase formation due to a partial electrolyte reduction on the Li{sub 4}Ti{sub 5}O{sub 12}/TiO{sub 2} composite surface.« less

Spatial Characteristics of Geothermal Spring Temperatures and Discharge Rates in the Tatun Volcanic Area, Taiwan

NASA Astrophysics Data System (ADS)

Jang, C. S.; Liu, C. W.

2014-12-01

The Tatun volcanic area is the only potential volcanic geothermal region in the Taiwan island, and abundant in hot spring resources owing to stream water mixing with fumarolic gases. According to the Meinzer's classification, spring temperatures and discharge rates are the most important properties for characterizing spring classifications. This study attempted to spatially characterize spring temperatures and discharge rates in the Tatun volcanic area, Taiwanusing indicator kriging (IK). First, data on spring temperatures and discharge rates, which were collected from surveyed data of the Taipei City Government, were divided into high, moderate and low categories according to spring classification criteria, and the various categories were regarded as estimation thresholds. Then, IK was adopted to model occurrence probabilities of specified temperatures and discharge rates in springs, and to determine their classifications based on estimated probabilities. Finally, nine combinations were obtained from the classifications of temperatures and discharge rates in springs. Moreover, the combinations and features of spring water were spatially quantified according to seven sub-zones of spring utilization. A suitable and sustainable development strategy of the spring area was proposed in each sub-zone based on probability-based combinations and features of spring water.The research results reveal that the probability-based classifications using IK provide an excellent insight in exploring the uncertainty of spatial features in springs, and can provide Taiwanese government administrators with detailed information on sustainable spring utilization and conservation in the overexploited spring tourism areas. The sub-zones BT (Beitou), RXY (Rd. Xingyi), ZSL (Zhongshanlou) and LSK (Lengshuikeng) with high or moderate discharge rates are suitable to supply spring water for tourism hotels.Local natural hot springs should be planned in the sub-zones DBT (Dingbeitou), ZSL, XYK (Xiayoukeng), and MC (Macao) with low discharge rates, and low or moderate temperatures, particularly in riverbeds or valleys.Keywords: Spring; Temperature; Discharge rate; Indicator kriging; Uncertainty

Behavior of motor units in human biceps brachii during a submaximal fatiguing contraction.

PubMed

Garland, S J; Enoka, R M; Serrano, L P; Robinson, G A

1994-06-01

The activity of 50 single motor units was recorded in the biceps brachii muscle of human subjects while they performed submaximal isometric elbow flexion contractions that were sustained to induce fatigue. The purposes of this study were to examine the influence of fatigue on motor unit threshold force and to determine the relationship between the threshold force of recruitment and the initial interimpulse interval on the discharge rates of single motor units during a fatiguing contraction. The discharge rate of most motor units that were active from the beginning of the contraction declined during the fatiguing contraction, whereas the discharge rates of most newly recruited units were either constant or increased slightly. The absolute threshold forces of recruitment and derecruitment decreased, and the variability of interimpulse intervals increased after the fatigue task. The change in motor unit discharge rate during the fatigue task was related to the initial rate, but the direction of the change in discharge rate could not be predicted from the threshold force of recruitment or the variability in the interimpulse intervals. The discharge rate of most motor units declined despite an increase in the excitatory drive to the motoneuron pool during the fatigue task.

Template-Free Synthesis of Sb2S3 Hollow Microspheres as Anode Materials for Lithium-Ion and Sodium-Ion Batteries

NASA Astrophysics Data System (ADS)

Xie, Jianjun; Liu, Li; Xia, Jing; Zhang, Yue; Li, Min; Ouyang, Yan; Nie, Su; Wang, Xianyou

2018-03-01

Hierarchical Sb2S3 hollow microspheres assembled by nanowires have been successfully synthesized by a simple and practical hydrothermal reaction. The possible formation process of this architecture was investigated by X-ray diffraction, focused-ion beam-scanning electron microscopy dual-beam system, and transmission electron microscopy. When used as the anode material for lithium-ion batteries, Sb2S3 hollow microspheres manifest excellent rate property and enhanced lithium-storage capability and can deliver a discharge capacity of 674 mAh g-1 at a current density of 200 mA g-1 after 50 cycles. Even at a high current density of 5000 mA g-1, a discharge capacity of 541 mAh g-1 is achieved. Sb2S3 hollow microspheres also display a prominent sodium-storage capacity and maintain a reversible discharge capacity of 384 mAh g-1 at a current density of 200 mA g-1 after 50 cycles. The remarkable lithium/sodium-storage property may be attributed to the synergetic effect of its nanometer size and three-dimensional hierarchical architecture, and the outstanding stability property is attributed to the sufficient interior void space, which can buffer the volume expansion. [Figure not available: see fulltext.

Local Structure Evolution and Modes of Charge Storage in Secondary Li–FeS 2 Cells

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

Butala, Megan M.; Mayo, Martin; Doan-Nguyen, Vicky V. T.

2017-03-27

In the pursuit of high-capacity electrochemical energy storage, a promising domain of research involves conversion reaction schemes, wherein electrode materials are fully transformed during charge and discharge. There are, however, numerous difficulties in realizing theoretical capacity and high rate capability in many conversion schemes. Here we employ operando studies to understand the conversion material FeS2, focusing on the local structure evolution of this relatively reversible material. X-ray absorption spectroscopy, pair distribution function analysis, and first-principles calculations of intermediate structures shed light on the mechanism of charge storage in the Li-FeS2 system, with some general principles emerging for charge storage inmore » chalcogenide materials. Focusing on second and later charge/discharge cycles, we find small, disordered domains that locally resemble Fe and Li2S at the end of the first discharge. Upon charge, this is converted to a Li-Fe-S composition whose local structure reveals tetrahedrally coordinated Fe. With continued charge, this ternary composition displays insertion extraction behavior at higher potentials and lower Li content. The finding of hybrid modes of charge storage, rather than simple conversion, points to the important role of intermediates that appear to store charge by mechanisms that more closely resemble intercalation.« less

Generation of warm dense matter using an argon based capillary discharge laser

NASA Astrophysics Data System (ADS)

Rossall, A. K.; Tallents, G. J.

2015-06-01

Argon based capillary discharge lasers operating in the extreme ultra violet (EUV) at 46.9 nm with output up to 0.5 mJ energy per pulse and repetition rates up to 10 Hz are capable of focused irradiances of 109-1012 W cm-2 and can be used to generate plasma in the warm dense matter regime by irradiating solid material. To model the interaction between such an EUV laser and solid material, the 2D radiative-hydrodynamic code POLLUX has been modified to include absorption via direct photo-ionisation, a super-configuration model to describe the ionization-dependent electronic configurations and a calculation of plasma refractive indices for ray tracing of the incident EUV laser radiation. A simulation study is presented, demonstrating how capillary discharge lasers of 1200 ps pulse duration can be used to generate warm dense matter at close to solid densities with temperatures of a few eV and energy densities up to 1 × 105 J cm-3. Plasmas produced by EUV laser irradiation are shown to be useful for examining the properties of warm dense matter as, for example, plasma emission is not masked by hotter, less dense plasma emission that occurs with visible/infra-red laser target irradiation.

The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

USGS Publications Warehouse

Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Mathew; Clark, Jordan F.

2018-01-01

Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

The suitability of using dissolved gases to determine groundwater discharge to high gradient streams

NASA Astrophysics Data System (ADS)

Gleeson, Tom; Manning, Andrew H.; Popp, Andrea; Zane, Matthew; Clark, Jordan F.

2018-02-01

Determining groundwater discharge to streams using dissolved gases is known to be useful over a wide range of streamflow rates but the suitability of dissolved gas methods to determine discharge rates in high gradient mountain streams has not been sufficiently tested, even though headwater streams are critical as ecological habitats and water resources. The aim of this study is to test the suitability of using dissolved gases to determine groundwater discharge rates to high gradient streams by field experiments in a well-characterized, high gradient mountain stream and a literature review. At a reach scale (550 m) we combined stream and groundwater radon activity measurements with an in-stream SF6 tracer test. By means of numerical modeling we determined gas exchange velocities and derived very low groundwater discharge rates (∼15% of streamflow). These groundwater discharge rates are below the uncertainty range of physical streamflow measurements and consistent with temperature, specific conductance and streamflow measured at multiple locations along the reach. At a watershed-scale (4 km), we measured CFC-12 and δ18O concentrations and determined gas exchange velocities and groundwater discharge rates with the same numerical model. The groundwater discharge rates along the 4 km stream reach were highly variable, but were consistent with the values derived in the detailed study reach. Additionally, we synthesized literature values of gas exchange velocities for different stream gradients which show an empirical relationship that will be valuable in planning future dissolved gas studies on streams with various gradients. In sum, we show that multiple dissolved gas tracers can be used to determine groundwater discharge to high gradient mountain streams from reach to watershed scales.

Integrated simulations for fusion research in the 2030's time frame (white paper outline)

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

Friedman, Alex; LoDestro, Lynda L.; Parker, Jeffrey B.

This white paper presents the rationale for developing a community-wide capability for whole-device modeling, and advocates for an effort with the expectation of persistence: a long-term programmatic commitment, and support for community efforts. Statement of 2030 goal (two suggestions): (a) Robust integrated simulation tools to aid real-time experimental discharges and reactor designs by employing a hierarchy in fidelity of physics models. (b) To produce by the early 2030s a capability for validated, predictive simulation via integration of a suite of physics models from moderate through high fidelity, to understand and plan full plasma discharges, aid in data interpretation, carry outmore » discovery science, and optimize future machine designs. We can achieve this goal via a focused effort to extend current scientific capabilities and rigorously integrate simulations of disparate physics into a comprehensive set of workflows.« less

Method and means for measuring acoustic emissions

DOEpatents

Renken, Jr., Claus J.

1976-01-06

The detection of acoustic emissions emanating from an object is achieved with a capacitive transducer coupled to the object. The capacitive transducer is charged and then allowed to discharge with the rate of discharge being monitored. Oscillations in the rate of discharge about the normally exponential discharge curve for the capacitive transducer indicate the presence of acoustic emissions.

Synthesis of Mesoporous Co2+-Doped TiO2 Nanodisks Derived from Metal Organic Frameworks with Improved Sodium Storage Performance.

PubMed

Hong, Zhensheng; Kang, Meiling; Chen, Xiaohui; Zhou, Kaiqiang; Huang, Zhigao; Wei, Mingdeng

2017-09-20

TiO 2 is a most promising anode candidate for rechargeable Na-ion batteries (NIBs) because of its appropriate working voltage, low cost, and superior structural stability during chage/discharge process. Nevertheless, it suffers from intrinsically low electrical conductivity. Herein, we report an in situ synthesis of Co 2+ -doped TiO 2 through the thermal treatment of metal organic frameworks precursors of MIL-125(Ti)-Co as a superior anode material for NIBs. The Co 2+ -doped TiO 2 possesses uniform nanodisk morphology, a large surface area and mesoporous structure with narrow pore distribution. The reversible capacity, Coulombic efficiency (CE) and rate capability can be improved by Co 2+ doping in mesoporous TiO 2 anode. Co 2+ -doped mesoporous TiO 2 nanodisks exhibited a high reversible capacity of 232 mAhg -1 at 0.1 Ag 1- , good rate capability and cycling stability with a stable capacity of about 140 mAhg -1 at 0.5 Ag 1- after 500 cycles. The enhanced Na-ion storage performance could be due to the increased electrical conductivity revealed by Kelvin probe force microscopy measurements.

Different proportions of C/KCu7S4 hybrid structure for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Dai, Shuge; Xi, Yi; Hu, Chenguo; Yue, Xule; Cheng, Lu; Wang, Guo

2014-10-01

KCu7S4 has the channel structure and minor resistance. Its double larger channels ensure that the ions can well exchange with other's, at the same time, can shorten the ionic diffusion path and improve the ionic and electronic transport. So KCu7S4 shows good electrochemical property. The paper reports a novel and high performance supercapacitor based on hybrid carbon particles and KCu7S4 (C/KCu7S4) electrode. For the hybrid structure with different proportions of C and KCu7S4, the C/KCu7S4 (1:10) hybrid supercapacitor shows preferable electrochemical performance and large specific capacitance (469 mF cm-2) at high charge-discharge rate (2 mA), still retaining ∼95% of the capacitance over 5000 cycles by charge-discharge process at a fixed current of 10 mA. Three supercapacitor units in series can light 50 light-emitting diodes (LEDs) for 2.5 min, 10 LEDs for 4 min, one LED for 5.5 min. The much-increased capacity, rate capability, and cycling stability may be attributed to the superionic conductive KCu7S4 nanowires and C/KCu7S4 hybrid structure, which improve ionic and electronic transport, enhance the kinetics of redox reactions through the electrode system.

Facile Synthesis of Three-Dimensional Heteroatom-Doped and Hierarchical Egg-Box-Like Carbons Derived from Moringa oleifera Branches for High-Performance Supercapacitors.

PubMed

Cai, Yijin; Luo, Ying; Xiao, Yong; Zhao, Xiao; Liang, Yeru; Hu, Hang; Dong, Hanwu; Sun, Luyi; Liu, Yingliang; Zheng, Mingtao

2016-12-07

In this paper, we demonstrate that Moringa oleifera branches, a renewable biomass waste with abundant protein content, can be employed as novel precursor to synthesize three-dimensional heteroatom-doped and hierarchical egg-box-like carbons (HEBLCs) by a facile room-temperature pretreatment and direct pyrolysis process. The as-prepared HEBLCs possess unique egg-box-like frameworks, high surface area, and interconnected porosity as well as the doping of heteroatoms (oxygen and nitrogen), endowing its excellent electrochemical performances (superior capacity, high rate capability, and outstanding cycling stability). Therefore, the resultant HEBLC manifests a maximum specific capacitance of 355 F g -1 at current density of 0.5 A g -1 and remarkable rate performance. Moreover, 95% of capacitance retention of HEBLCs can be also achieved after 20 000 charge-discharge cycles at an extremely high current density (20 A g -1 ), indicating a prominent cycling stability. Furthermore, the as-assembled HEBLC//HEBLC symmetric supercapacitor displays a superior energy density of 20 Wh kg -1 in aqueous electrolyte and remarkable capacitance retention (95.6%) after 10 000 charge-discharge cycles. This work provides an environmentally friendly and reliable method to produce higher-valued carbon nanomaterials from renewable biomass wastes for energy storage applications.

Functional and stability orientation synthesis of materials and structures in aprotic Li-O2 batteries.

PubMed

Zhang, Peng; Zhao, Yong; Zhang, Xinbo

2018-04-23

The lithium-O2 battery is one of most promising energy storage and conversion devices due to its ultrahigh theoretical energy density and hence has broad application potential in electrical vehicles and stationary power systems. However, the present Li-O2 battery suffers from a series of challenges for its practical application, such as its low capacity and rate capability, poor round-trip efficiency and short cycle life. These challenges mainly arise from the sluggish and unsustainable discharge and charge reactions at lithium and oxygen electrodes, which determine the performance and durability of a battery. In this review, we first provide insights on the present understanding of the discharge/charge mechanism of such a battery and follow up with establishing a correlation between the specific materials/structures of the battery modules and their functionality/stability within the recent progress in electrodes, electrolytes and redox mediators. Considerable emphasis is paid to the importance of functional orientation design and the synthesis of materials/structures towards accelerating and sustaining the electrode reactions of Li-O2 batteries. Moreover, the future directions and perspectives of rationally constructed material and surface/interface structures, as well as their optimal combinations are proposed for enhancement of the electrode reaction rate and sustainability, and consequently for a better performance and durability of such batteries.

Relationships between ecosystem metabolism, benthic macroinvertebrate densities, and environmental variables in a sub-arctic Alaskan river

USGS Publications Warehouse

Benson, Emily R.; Wipfli, Mark S.; Clapcott, Joanne E.; Hughes, Nicholas F.

2013-01-01

Relationships between environmental variables, ecosystem metabolism, and benthos are not well understood in sub-arctic ecosystems. The goal of this study was to investigate environmental drivers of river ecosystem metabolism and macroinvertebrate density in a sub-arctic river. We estimated primary production and respiration rates, sampled benthic macroinvertebrates, and monitored light intensity, discharge rate, and nutrient concentrations in the Chena River, interior Alaska, over two summers. We employed Random Forests models to identify predictor variables for metabolism rates and benthic macroinvertebrate density and biomass, and calculated Spearman correlations between in-stream nutrient levels and metabolism rates. Models indicated that discharge and length of time between high water events were the most important factors measured for predicting metabolism rates. Discharge was the most important variable for predicting benthic macroinvertebrate density and biomass. Primary production rate peaked at intermediate discharge, respiration rate was lowest at the greatest time since last high water event, and benthic macroinvertebrate density was lowest at high discharge rates. The ratio of dissolved inorganic nitrogen to soluble reactive phosphorus ranged from 27:1 to 172:1. We found that discharge plays a key role in regulating stream ecosystem metabolism, but that low phosphorous levels also likely limit primary production in this sub-arctic stream.

Method of inducing differential etch rates in glow discharge produced amorphous silicon

DOEpatents

Staebler, David L.; Zanzucchi, Peter J.

1980-01-01

A method of inducing differential etch rates in glow discharge produced amorphous silicon by heating a portion of the glow discharge produced amorphous silicon to a temperature of about 365.degree. C. higher than the deposition temperature prior to etching. The etch rate of the exposed amorphous silicon is less than the unheated amorphous silicon.

46 CFR 108.437 - Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Pipe sizes and discharge rates for enclosed ventilation... Systems Fixed Carbon Dioxide Fire Extinguishing Systems § 108.437 Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment. (a) The minimum pipe size for the initial...

46 CFR 108.437 - Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment. 108.437 Section 108.437 Shipping COAST GUARD, DEPARTMENT OF... Systems Fixed Carbon Dioxide Fire Extinguishing Systems § 108.437 Pipe sizes and discharge rates for...

Estimation of Uncertainties in Stage-Discharge Curve for an Experimental Himalayan Watershed

NASA Astrophysics Data System (ADS)

Kumar, V.; Sen, S.

2016-12-01

Various water resource projects developed on rivers originating from the Himalayan region, the "Water Tower of Asia", plays an important role on downstream development. Flow measurements at the desired river site are very critical for river engineers and hydrologists for water resources planning and management, flood forecasting, reservoir operation and flood inundation studies. However, an accurate discharge assessment of these mountainous rivers is costly, tedious and frequently dangerous to operators during flood events. Currently, in India, discharge estimation is linked to stage-discharge relationship known as rating curve. This relationship would be affected by a high degree of uncertainty. Estimating the uncertainty of rating curve remains a relevant challenge because it is not easy to parameterize. Main source of rating curve uncertainty are errors because of incorrect discharge measurement, variation in hydraulic conditions and depth measurement. In this study our objective is to obtain best parameters of rating curve that fit the limited record of observations and to estimate uncertainties at different depth obtained from rating curve. The rating curve parameters of standard power law are estimated for three different streams of Aglar watershed located in lesser Himalayas by maximum-likelihood estimator. Quantification of uncertainties in the developed rating curves is obtained from the estimate of variances and covariances of the rating curve parameters. Results showed that the uncertainties varied with catchment behavior with error varies between 0.006-1.831 m3/s. Discharge uncertainty in the Aglar watershed streams significantly depend on the extent of extrapolation outside the range of observed water levels. Extrapolation analysis confirmed that more than 15% for maximum discharges and 5% for minimum discharges are not strongly recommended for these mountainous gauging sites.

Oscillations in motor unit discharge are reflected in the low-frequency component of rectified surface EMG and the rate of change in force.

PubMed

Yoshitake, Yasuhide; Shinohara, Minoru

2013-11-01

Common drive to a motor unit (MU) pool manifests as low-frequency oscillations in MU discharge rate, producing fluctuations in muscle force. The aim of the study was to examine the temporal correlation between instantaneous MU discharge rate and rectified EMG in low frequencies. Additionally, we attempted to examine whether there is a temporal correlation between the low-frequency oscillations in MU discharge rate and the first derivative of force (dF/dt). Healthy young subjects produced steady submaximal force with their right finger as a single task or while maintaining a pinch-grip force with the left hand as a dual task. Surface EMG and fine-wire MU potentials were recorded from the first dorsal interosseous muscle in the right hand. Surface EMG was band-pass filtered (5-1,000 Hz) and full-wave rectified. Rectified surface EMG and the instantaneous discharge rate of MUs were smoothed by a Hann-window of 400 ms duration (equivalent to 2 Hz low-pass filtering). In each of the identified MUs, the smoothed MU discharge rate was positively correlated with the rectified-and-smoothed EMG as confirmed by the distinct peak in cross-correlation function with greater values in the dual task compared with the single task. Additionally, the smoothed MU discharge rate was temporally correlated with dF/dt more than with force and with rectified-and-smoothed EMG. The results indicated that the low-frequency component of rectified surface EMG and the first derivative of force provide temporal information on the low-frequency oscillations in the MU discharge rate.

Patients discharged against medical advice from a psychiatric hospital in Iran: a prospective study.

PubMed

Sheikhmoonesi, Fatemeh; Khademloo, Mohammad; Pazhuheshgar, Samaneh

2014-03-30

Self- discharged patients are at high risk for readmission and ultimately higher cost for care.We intended to find the proportion of patients who leave hospital against medical advice and explore some of their characteristics. This prospective study of discharge against medical advice was conducted in psychiatric wards of Zare hospital in Iran, 2011. A psychologist recorded some information on a checklist based on the documented information about the patient who wanted to leave against medical advice. The psychologist interviewed these patients and recorded the reasons for discharge against medical advice. Descriptive statistics were calculated for the variables. The rate of premature discharge was 34.4%. Compared to patients with regular discharges, patients with premature discharge were significantly more likely to be male, self-employed, to have co morbid substance abuse and first admission and positive family history of psychiatric disorder. Disappearance of symptoms was the most frequent reason for premature discharge. The 34.4% rate of premature discharge observed in our study is higher than rate reported in other studies. One possible explanation is our teaching hospital serves a low-income urban area and most patients had low socioeconomic status. Further studies are needed to compare teaching and non-teaching hospital about the rate of premature discharge and the reasons of patients who want to leave against medical advice.

Evolution of a plasma vortex in air

NASA Astrophysics Data System (ADS)

Tsai, Cheng-Mu; Chu, Hong-Yu

2016-01-01

We report the generation of a vortex-shaped plasma in air by using a capacitively coupled dielectric barrier discharge system. We show that a vortex-shaped plasma can be produced inside a helium gas vortex and is capable of propagating for 3 cm. The fluctuation of the plasma ring shows a scaling relation with the Reynolds number of the vortex. The transient discharge reveals the property of corona discharge, where the conducting channel within the gas vortex and the blur plasma emission are observed at each half voltage cycle.

Evolution of a plasma vortex in air.

PubMed

Tsai, Cheng-Mu; Chu, Hong-Yu

2016-01-01

We report the generation of a vortex-shaped plasma in air by using a capacitively coupled dielectric barrier discharge system. We show that a vortex-shaped plasma can be produced inside a helium gas vortex and is capable of propagating for 3 cm. The fluctuation of the plasma ring shows a scaling relation with the Reynolds number of the vortex. The transient discharge reveals the property of corona discharge, where the conducting channel within the gas vortex and the blur plasma emission are observed at each half voltage cycle.

Numerical simulation of compact intracloud discharge and generated electromagnetic pulse

NASA Astrophysics Data System (ADS)

Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.

2015-06-01

Using the concept of the relativistic runaway electron avalanche, numerical simulation of compact intracloud discharge as a generator of powerful natural electromagnetic pulses (EMPs) in the HF-UHF range was conducted. We evaluated the numbers of electrons initiating the avalanche, with which the calculated EMP characteristics are consistent with measured ones. The discharge capable of generating EMPs produces runaway electrons in numbers close to those in the source of terrestrial γ-flashes (TGF) registered in the nearest space, which may be an argument for a joint EMP and TGF source.

38 CFR 4.30 - Convalescent ratings.

Code of Federal Regulations, 2010 CFR

2010-07-01

... RATING DISABILITIES General Policy in Rating § 4.30 Convalescent ratings. A total disability rating (100... by report at hospital discharge (regular discharge or release to non-bed care) or outpatient release... total ratings will not be subject to § 3.105(e) of this chapter. Such total rating will be followed by...

Predictors and variation of routine home discharge in critically ill adults with cystic fibrosis.

PubMed

Oud, Lavi; Chan, Yiu Ming

2018-06-01

The short-term outcomes of patients with cystic fibrosis (CF) surviving critical illness were not examined systematically. To determine the factors associated with and variation in rates of routine home discharge among ICU-managed adult CF patients. Predictors of routine home discharge and its hospital-level variation were examined in ICU-managed adults with cystic fibrosis in Texas during 2004-2013. Older age, rural residence, and severity of illness decreased odds of routine home discharge, while hospitalization in facilities accredited as part of the Cystic Fibrosis Foundation Care Center Network nearly doubled the odds of routine home discharge. The median (interquartile) adjusted rate of routine home discharge was 62.0% (31.5-82.5). The identified determinants of routine home discharge can inform clinical decision-making, while the demonstrated wide variation in adjusted across-hospital rates of routine home discharge of ICU-managed adults with CF can provide benchmark data for future quality improvement efforts. Published by Elsevier Inc.

Investigation and control of the {{\\rm{O}}}_{3}- to {NO}-transition in a novel sub-atmospheric pressure dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Bansemer, Robert; Schmidt-Bleker, Ansgar; van Rienen, Ursula; Weltmann, Klaus-Dieter

2017-06-01

A novel flow-driven dielectric barrier discharge concept is presented, which uses a Venturi pump to transfer plasma-generated reactive oxygen and nitrogen species from a sub-atmospheric pressure (200{--}600 {mbar}) discharge region to ambient pressure and can be operated with air. By adjusting the working pressure of the device, the plasma chemistry can be tuned continuously from an ozone ({{{O}}}3)-dominated mode to a nitrogen oxides ({{NO}}x)-only mode. The plasma source is characterized focusing on the mechanisms effecting this mode change. The composition of the device’s output gas was determined using Fourier-transform infrared spectroscopy. The results are correlated to measurements of discharge chamber pressure and temperature as well as of input power. It is found that the mode-change temperature can be controlled by the discharge chamber pressure. The source concept is capable of generating an {{NO}}x-dominated plasma chemistry at gas temperatures distinctly below 400 {{K}}. Through mixing of the processed gas stream with a second flow of pressurized air required for the operation of the Venturi pump, the resulting product gas stream remains close to room temperature. A reduced zero-dimensional reaction kinetics model with only seven reactions is capable of describing the observed pressure- and temperature-dependence of the {{{O}}}3 to {{NO}}x mode-change.

A Geochemical and Geophysical Assessment of Coastal Groundwater Discharge at Select Sites in Maui and O’ahu, Hawai’i

USGS Publications Warehouse

Swarzenski, Peter W.; Storlazzi, Curt; M.L. Dalier,; C.R. Glenn,; C.G. Smith,

2015-01-01

Based on the submarine groundwater discharge tracer 222Rn, coastal groundwater discharge rates ranged from about 22–50 cm per day at Kahekili, a site in the Ka’anapali region north of Lahaina in west Maui, while at Black Point in Maunalua Bay along southern O’ahu, coastal groundwater discharge rates ranged up to 700 cm per day, although the mean discharge rate at this site was 60 cm per day. The water chemistry of the discharging groundwater can be dramatically different than ambient seawater at both coastal sites. For example, at Kahekili the average concentrations of dissolved inorganic nitrogen (DIN), dissolved silicate (DSi) and total dissolved phosphorus (TDP) were roughly 188-, 36-, and 106-times higher in the discharging groundwater relative to ambient seawater, respectively. Such data extend our basic understanding of the physical controls on coastal groundwater discharge and provide an estimate of the magnitude and physical forcings of submarine groundwater discharge and associated trace metal and nutrient loads conveyed by this submarine route.

Hospital Ownership of a Postacute Care Facility Influences Discharge Destinations After Emergent Surgery.

PubMed

Abdelsattar, Zaid M; Gonzalez, Andrew A; Hendren, Samantha; Regenbogen, Scott E; Wong, Sandra L

2016-08-01

The aim of the study was to identify hospital characteristics associated with variation in patient disposition after emergent surgery. Colon resections in elderly patients are often done in emergent settings. Although these operations are known to be riskier, there are limited data regarding postoperative discharge destination. We evaluated Medicare beneficiaries who underwent emergent colectomy between 2008 and 2010. Using hierarchical logistic regression, we estimated patient and hospital-level risk-adjusted rates of nonhome discharges. Hospitals were stratified into quintiles based on their nonhome discharge rates. Generalized linear models were used to identify hospital structural characteristics associated with nonhome discharges (comparing discharge to skilled nursing facilities vs home with/without home health services). Of the 122,604 patients surviving to discharge after emergent colectomy at 3012 hospitals, 46.7% were discharged to a nonhome destination. There was a wide variation in risk and reliability-adjusted nonhome discharge rates across hospitals (15% to 80%). Patients at hospitals in the highest quintile of nonhome discharge rates were more likely to have longer hospitalizations (15.1 vs 13.2; P < 0.001) and more complications (43.2% vs 34%; P < 0.001). On multivariable analysis, only hospital ownership of a skilled nursing facility (P < 0.001), teaching status (P = 0.025), and low nurse-to-patient ratios (P = 0.002) were associated with nonhome discharges. Nearly half of Medicare beneficiaries are discharged to a nonhome destination after emergent colectomy. Hospital ownership of a skilled nursing facility and low nurse-to-patient ratios are highly associated with nonhome discharges. This may signify the underlying financial incentives to preferentially utilize postacute care facilities under the traditional fee-for-service payment model.

Is There an Association Between Markers of Cardiovascular Autonomic Dysfunction at Discharge From Rehabilitation and Participation 1 and 5 Years Later in Individuals With Spinal Cord Injury?

PubMed

Rianne Ravensbergen, H J; de Groot, Sonja; Post, Marcel W; Bongers-Janssen, Helma M; van der Woude, Lucas H; Claydon, Victoria E

2016-09-01

To determine whether physical activity and participation 1 and 5 years after discharge are associated with measures of cardiovascular autonomic function: prevalence of hypotension and reduced peak heart rate at discharge from initial inpatient spinal cord injury (SCI) rehabilitation. Prospective cohort study. Rehabilitation centers. Individuals with SCI (N=146). Not applicable. We recorded markers of cardiovascular autonomic dysfunction (resting blood pressure and peak heart rate) and personal and lesion characteristics at the time of discharge from rehabilitation. Parameters for participation (social health status dimension of the Sickness Impact Profile) and physical activity (Physical Activity Scale for Individuals with Physical Disabilities [PASIPD]) were measured 1 and 5 years after discharge. Effects of prevalence of cardiovascular autonomic dysfunction were analyzed using linear regression analysis while correcting for possible confounders. We found no significant association between hypotension and social health status dimension of the Sickness Impact Profile or PASIPD, either at 1 or at 5 years after discharge. A significant association between peak heart rate and social health status dimension of the Sickness Impact Profile was found at 1 year after discharge, showing poorer participation in individuals with low peak heart rate (ie, cardiovascular autonomic dysfunction). The unadjusted relation between peak heart rate and the social health status dimension of the Sickness Impact Profile was significant at 5 years, but not when adjusted for confounders. We found associations between peak heart rate and PASIPD for both 1 and 5 years after discharge; however, these were not significant after correction for potential confounding factors. Autonomic dysfunction after SCI is a crucial factor influencing quality of life. We found that cardiovascular autonomic impairment, assessed from low peak heart rate, was associated with reduced participation after 1 year. The results suggest that peak heart rate at discharge from rehabilitation after SCI should be used to identify those needing additional support to facilitate physical activity and participation after discharge. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

An investigation of manganese based electrode materials for use in lithium ion batteries

NASA Astrophysics Data System (ADS)

Sengupta, Surajit

Lithium-based batteries are potential candidates to provide maximum volumetric and gravimetric energy density. One of the most attractive candidates as a cathode material for secondary lithium ion battery systems is the spinel LiMn 2O4 because it is environmentally friendly, less expensive and is capable of providing high energy density as compared to other cathode materials that are currently available. One problem associated with the spinel structure is capacity fading during multiple cycles of charge and discharge operations. This behaviour is due in part to the structural distortion during deep charge and discharge where nearly 100% of the lithium is extracted and inserted inside the spinel structure. Capacity fading can also be caused by dissolution of manganese ions in the electrolyte phase. A solution based method has been adapted for the synthesis of lithium manganese oxide, and chromium and cobalt doped mixed oxide materials using polyvinyl alcohol (PVA) as a chelating agent. It has been found from TGA/DSC analysis that at around 220°C the synthesis reaction is completed. The precursor powders obtained were annealed at different temperatures and times in the range of 250°C to 600°C and from 2 to 8 hours respectively to obtain pure spinel oxides. From X-ray analysis it has been observed that the crystallite size can be controlled in the range of approximately 6 nm to 32 nm depending on the annealing time and the temperature. The morphology of the synthesized materials consisted of submicron sized particles agglomerated with micropores inside the network structure. To observe the effect of physical properties on battery performance cyclic chronopotentiometric evaluation was conducted. It has been found with these synthesized materials that there is an increase in the 1st discharge capacity with an increase in the annealing time and the temperature at both 1C and C/5 rates. This increase is more significant when the annealing temperature is 600°C as compared to that at 250°C. This implies that an increase in particle size may improve the initial discharge capacity. It was observed that at the discharge rate of 1C, the material annealed at 600°C for 8 hours showed the best performance with respect to an average initial discharge capacity, energy density and capacity retention. However, it was found that the initial discharge capacity, the energy density and the capacity retention are poor for highly crystalline, micron sized lithium manganese oxide cathode material. (Abstract shortened by UMI.)

Electric-discharge-pumped nitrogen ion laser

NASA Technical Reports Server (NTRS)

Laudenslager, J. B.; Pacala, T. J.; Wittig, C.

1976-01-01

The routine operation is described of an N2(+) laser oscillating on the first negative band system of N2(+) which is produced in a preionized transverse discharge device. The discharge design incorporates features which favor the efficient production of the excitation transfer reaction of He2(+) with N2. A capacitive discharge switched by means of a high-current grounded grid thyratron is used to meet the design requirement of a volumetric discharge in high-pressure gas mixtures where the electric discharge need not have an ultrafast rise time (greater than 10 nsec) but should be capable of transferring large quantities of stored electric energy to the gas. A peak power of 180 kW in an 8-nsec laser pulse was obtained with a 0.1% mixture of N2 in helium at a total pressure of 3 atm. The most intense laser oscillations were observed on the (0,1) vibrational transition at 427.8 microns.

Ion optics for high power 50-cm-diam ion thrusters

NASA Technical Reports Server (NTRS)

Rawlin, Vincent K.; Millis, Marc G.

1989-01-01

The process used at the NASA-Lewis to fabricate 30 and 50-cm-diameter ion optics is described. The ion extraction capabilities of the 30 and 50-cm diameter ion optics were evaluated on divergent field and ring-cusp discharge chambers and compared. Perveance was found to be sensitive to the effects of the type and power of the discharge chamber and to the accelerator electrode hole diameter. Levels of up to 0.64 N and 20 kW for thrust and input power, respectively, were demonstrated with the divergent-field discharge chamber. Thruster efficiencies and specific impulse values up to 79 percent and 5000 sec., respectively, were achieved with the ring-cusp discharge chamber.

Laser-assisted guiding of electric discharges around objects

PubMed Central

Clerici, Matteo; Hu, Yi; Lassonde, Philippe; Milián, Carles; Couairon, Arnaud; Christodoulides, Demetrios N.; Chen, Zhigang; Razzari, Luca; Vidal, François; Légaré, François; Faccio, Daniele; Morandotti, Roberto

2015-01-01

Electric breakdown in air occurs for electric fields exceeding 34 kV/cm and results in a large current surge that propagates along unpredictable trajectories. Guiding such currents across specific paths in a controllable manner could allow protection against lightning strikes and high-voltage capacitor discharges. Such capabilities can be used for delivering charge to specific targets, for electronic jamming, or for applications associated with electric welding and machining. We show that judiciously shaped laser radiation can be effectively used to manipulate the discharge along a complex path and to produce electric discharges that unfold along a predefined trajectory. Remarkably, such laser-induced arcing can even circumvent an object that completely occludes the line of sight. PMID:26601188

High Voltage SPT Performance

NASA Technical Reports Server (NTRS)

Manzella, David; Jacobson, David; Jankovsky, Robert

2001-01-01

A 2.3 kW stationary plasma thruster designed to operate at high voltage was tested at discharge voltages between 300 and 1250 V. Discharge specific impulses between 1600 and 3700 sec were demonstrated with thrust between 40 and 145 mN. Test data indicated that discharge voltage can be optimized for maximum discharge efficiency. The optimum discharge voltage was between 500 and 700 V for the various anode mass flow rates considered. The effect of operating voltage on optimal magnet field strength was investigated. The effect of cathode flow rate on thruster efficiency was considered for an 800 V discharge.

[Exercise stress test and dobutamine stress echocardiography for the prognostic stratification after uncomplicated acute myocardial infarction].

PubMed

Vitiello, Nicola; Cirillo, Raffaele; Granato, Luigi; Coppola, Vincenzo; di Palma, Francesco

2007-05-01

Exercise stress test and dobutamine stress echocardiography are usually performed early after an uncomplicated acute myocardial infarction in the prognostic stratification of patients to define the optimal diagnostic and therapeutic procedure. The aim of this study was to evaluate if the association of an imaging test could increase exercise test capability to identify patients with residual ischemia and patients at high risk of events in the follow-up. Four hundred and forty-two consecutive patients underwent exercise stress testing and dobutamine stress echocardiography before discharge and subsequently coronary angiography within 30 days. In case of submaximal negative result at the exercise test, this was repeated 20 days after discharge. The follow-up lasted 26.8 +/- 9 months. The endpoints were death, reinfarction, and unstable angina requiring hospitalization or revascularization intervention. Both tests and their association showed a higher sensitivity in males; in females dobutamine stress echocardiography had a higher specificity. In females, the addition of dobutamine stress echocardiography increased either the negative or the positive prognostic values of exercise stress test by 31% and 5.6%, respectively. In males, the negative prognostic value increased by 15.5%, whereas the positive prognostic value decreased by 12%. A low exercise capability (<6 METs) showed an event predictive value independent of test results and any other variables. The event-free survival curves correlated with exercise capability differed shortly after the first months both in males and females. These results suggest different stratification procedures with regard to gender: in males, the exercise stress test might be sufficient at discharge, to be repeated 20 days later, if submaximal negative. In females, it seems to be useful to associate an imaging test at discharge. In any case, the exercise stress test remains the main step in the stratification procedure also for its capability to identify patients who are at high risk of events in the follow-up.

Construction of Hierarchical α-MnO2 Nanowires@Ultrathin δ-MnO2 Nanosheets Core-Shell Nanostructure with Excellent Cycling Stability for High-Power Asymmetric Supercapacitor Electrodes.

PubMed

Ma, Zhipeng; Shao, Guangjie; Fan, Yuqian; Wang, Guiling; Song, Jianjun; Shen, Dejiu

2016-04-13

Poor electrical conductivity and mechanical instability are two major obstacles to realizing high performance of MnO2 as pseudocapacitor material. The construction of unique hierarchical core-shell nanostructures, therefore, plays an important role in the efficient enhancement of the rate capacity and the stability of this material. We herein report the fabrication of a hierarchical α-MnO2 nanowires@ultrathin δ-MnO2 nanosheets core-shell nanostructure by adopting a facile and practical solution-phase technique. The novel hierarchical nanostructures are composed of ultrathin δ-MnO2 nanosheets with a few atomic layers growing well on the surface of the ultralong α-MnO2 nanowires. The first specific capacitance of hierarchical core-shell nanostructure reached 153.8 F g(-1) at the discharge current density of as high as 20 A g(-1), and the cycling stability is retained at 98.1% after 10,000 charge-discharge cycles, higher than those in the literature. The excellent rate capacity and stability of the hierarchical core-shell nanostructures can be attributed to the structural features of the two MnO2 crystals, in which a 1D α-MnO2 nanowire core provides a stable structural backbone and the ultrathin 2D δ-MnO2 nanosheet shell creates more reactive active sites. The synergistic effects of different dimensions also contribute to the superior rate capability.

Surface modification of cathode material 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2 by alumina for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Li, Yonghu; Chang, Xingping; Xu, Qunjie; Lai, Chunyan; Liu, Xinnuan; Yuan, Xiaolei; Liu, Haimei; Min, Yulin

2018-02-01

In an attempt to overcome the irreversible capacity loss occurred during the first cycle and stabilize the surface structure, an alumina coating layer has been triumphantly prepared on the surface of 0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2 cathode material with different amounts (1, 2, and 3 wt%) through a simple hydrolysis reaction, followed by an annealing process. The results reveal that the coated materials have a higher crystallinity and the particles are evenly distributed. As a cathode material for lithium-ion batteries, the 2-wt% coated sample delivers initial discharge specific capacity of 211.7 mAh g-1 at a rate of 1 C between 2.0 and 4.8 V with an initial columbic efficiency of 73.2%. Meanwhile, it exhibits the highest discharge specific capacity of 206.2 mAh g-1 with 97.4% capacity retention after 100 cycles at and much elevated rate capability compared to uncoated material. The excellent cycling stability and more superior rate property can be ascribed to alumina coating layer, which has a surface stabilization effect on these cathode materials, lessening the dissolution of metal ions. The electrochemical impedance and cyclic voltammetry studies indicate that coated by alumina improved the kinetic performance for lithium-rich layered materials, showing a prospect for practical lithium battery application.

Carbon-Coated, Diatomite-Derived Nanosilicon as a High Rate Capable Li-ion Battery Anode.

PubMed

Campbell, Brennan; Ionescu, Robert; Tolchin, Maxwell; Ahmed, Kazi; Favors, Zachary; Bozhilov, Krassimir N; Ozkan, Cengiz S; Ozkan, Mihrimah

2016-10-07

Silicon is produced in a variety of ways as an ultra-high capacity lithium-ion battery (LIB) anode material. The traditional carbothermic reduction process required is expensive and energy-intensive; in this work, we use an efficient magnesiothermic reduction to convert the silica-based frustules within diatomaceous earth (diatomite, DE) to nanosilicon (nanoSi) for use as LIB anodes. Polyacrylic acid (PAA) was used as a binder for the DE-based nanoSi anodes for the first time, being attributed for the high silicon utilization under high current densities (up to 4C). The resulting nanoSi exhibited a high BET specific surface area of 162.6 cm 2 g -1 , compared to a value of 7.3 cm 2 g -1 for the original DE. DE contains SiO 2 architectures that make ideal bio-derived templates for nanoscaled silicon. The DE-based nanoSi anodes exhibit good cyclability, with a specific discharge capacity of 1102.1 mAh g -1 after 50 cycles at a C-rate of C/5 (0.7 A g Si -1 ) and high areal loading (2 mg cm -2 ). This work also demonstrates the fist rate capability testing for a DE-based Si anode; C-rates of C/30 - 4C were tested. At 4C (14.3 A g Si -1 ), the anode maintained a specific capacity of 654.3 mAh g -1 - nearly 2x higher than graphite's theoretical value (372 mAh g -1 ).

Mortality in infants discharged from neonatal intensive care units in Georgia.

PubMed

Allen, D M; Buehler, J W; Samuels, B N; Brann, A W

Although neonatal intensive care units (NICUs) have contributed to advances in neonatal survival, little is known about the epidemiology of deaths that occur after NICU discharge. To determine mortality rates following NICU discharge, we used linked birth, death, and NICU records for infants born to Georgia residents from 1980 through 1982 and who were admitted to NICUs participating in the state's perinatal care network. Infants who died after discharge (n = 120) had a median duration of NICU hospitalization of 20 days (range, 1 to 148 days) and a median birth weight of 1983 g (range, 793 to 5159 g). The postdischarge mortality rate was 22.7 per 1000 NICU discharges. This rate is more than five times the overall postneonatal mortality rate for Georgia from 1980 to 1982. The most common causes of death were congenital heart disease (23%), sudden infant death syndrome (21%), and infection (13%). Demographic characteristics commonly associated with infant mortality were not strongly associated with the mortality following NICU discharge.

Laboratory Experiments Investigating Glacier Submarine Melt Rates and Circulation in an East Greenland Fjord

NASA Astrophysics Data System (ADS)

Cenedese, C.

2014-12-01

Idealized laboratory experiments investigate the glacier-ocean boundary dynamics near a vertical 'glacier' (i.e. no floating ice tongue) in a two-layer stratified fluid, similar to Sermilik Fjord where Helheim Glacier terminates. In summer, the discharge of surface runoff at the base of the glacier (subglacial discharge) intensifies the circulation near the glacier and increases the melt rate with respect to that in winter. In the laboratory, the effect of subglacial discharge is simulated by introducing fresh water at melting temperatures from either point or line sources at the base of an ice block representing the glacier. The circulation pattern observed both with and without subglacial discharge resembles those observed in previous studies. The buoyant plume of cold meltwater and subglacial discharge water entrains ambient water and rises vertically until it finds either the interface between the two layers or the free surface. The results suggest that the meltwater deposits within the interior of the water column and not entirely at the free surface, as confirmed by field observations. The submarine melt rate increases with the subglacial discharge rate. Furthermore, the same subglacial discharge causes greater submarine melting if it exits from a point source rather than from a line source. When the subglacial discharge exits from two point sources, two buoyant plumes are formed which rise vertically and interact. The results suggest that the distance between the two subglacial discharges influences the entrainment in the plumes and consequently the amount of submarine melting and the final location of the meltwater within the water column. Hence, the distribution and number of sources of subglacial discharge may play an important role in glacial melt rates and fjord stratification and circulation. Support was given by NSF project OCE-113008.

Experiences of nurse case managers within a central discharge planning role of collaboration between physicians, patients and other healthcare professionals: A sociocultural qualitative study.

PubMed

Thoma, Jorun E; Waite, Marion A

2018-03-01

To gain knowledge of nurse case managers' experiences within the German acute care context of collaboration with patients and physicians in a discharge planning role; further to learn about patients' assignment to the management of the nurse case managers; and explicitly to explore critical incidences of interactions between nurse case managers, patients and healthcare practitioner in discharge planning to understand the factor that contributes to effective collaboration. The defined role of nurse case managers in many contexts is a patient-centred responsibility for a central task of discharge management of patients with complex physical and social needs. Some studies have indicated that the general impact of the role reduces readmission rates. Given the necessity to work interprofessionally to achieve a safe discharge, little is known about how nurse case managers achieve this collaboratively. A qualitative case study within a German teaching hospital of nurse case managers (N = 8). Data were collected through semi-structured interviews prompted by a critical incident technique and rigorously analysed through the lenses of sociocultural theory. Consistent object being worked upon was a safe and effective discharge from hospital with a focus on patient advocacy. Significant themes were a self-value or recognition by others of professional expertise, reciprocal value on the capabilities of others thorough relational expertise and negotiation with patients and an identification of case trajectories. More continuity of nurse case managers' care and management, clarity of role and transparency to peers, physicians and other professionals would be beneficial in ensuring appropriate referral of complex patients to nurse case managers responsibility. Clearer role description and benefit realisation of the nurse case managers could be achieved by interventions that are interprofessional and focus on the tasks that matter from a collaborative perspective. This could lead to refinement of available indicators and policy developments. © 2018 John Wiley & Sons Ltd.

Transcardiac conducted electrical weapon (TASER) probe deployments: incidence and outcomes.

PubMed

Bozeman, William P; Teacher, Eric; Winslow, James E

2012-12-01

TASER (TASER International, Scottsdale, AZ) conducted electrical weapons (CEWs) are commonly used by law enforcement officers. Although animal studies have suggested that transcardiac CEW discharges may produce direct cardiac effects, this has not been demonstrated in human studies. This study sought to determine the incidence and outcomes of transcardiac CEW probe impact locations in a large series of actual CEW deployments. A multi-center database of consecutive CEW uses by law enforcement officers was retrospectively reviewed. Case report forms were independently reviewed by three investigators to identify cases with paired probe configurations potentially producing a transcardiac discharge vector. Descriptive analysis was performed and inter-rater reliability was assessed. Among 1201 total CEW uses, 813 included probe deployments and 178 cases had paired anterior probe impacts potentially capable of producing a transcardiac discharge vector. This represents 14.8% of all CEW uses (95% confidence interval [CI] 12.9-16.9%) and 21.9% of CEW uses in probe mode (95% CI 19.1-24.9%). Inter-rater agreement was very good, with kappa = 0.82. There were no immediate deaths in any cases (97.5% CI 0.0-0.3%) to suggest a cardiac dysrhythmia, including those with transcardiac discharge vector. CEW deployments with probe impact configurations capable of producing a transcardiac discharge occur in a minority of cases in field use conditions. None of these cases, transcardiac or otherwise, produced immediately fatal dysrhythmias. These data support the overall safety of CEWs and provide a benchmark estimate of the likelihood of transcardiac discharge vectors occurring in field use of CEWs. Copyright © 2012 Elsevier Inc. All rights reserved.

Recruitment and rate coding organisation for soleus motor units across entire range of voluntary isometric plantar flexions.

PubMed

Oya, Tomomichi; Riek, Stephan; Cresswell, Andrew G

2009-10-01

Unlike upper limb muscles, it remains undocumented as to how motor units in the soleus muscle are organised in terms of recruitment range and discharge rates with respect to their recruitment and de-recruitment thresholds. The possible influence of neuromodulation, such as persistent inward currents (PICs) on lower limb motor unit recruitment and discharge rates has also yet to be reported. To address these issues, electromyographic (EMG) activities from the soleus muscle were recorded using selective branched-wire intramuscular electrodes during ramp-and-hold contractions with intensities up to maximal voluntary contraction (MVC). The multiple single motor unit activities were then derived using a decomposition technique. The onset-offset hysteresis of motor unit discharge, i.e. a difference between recruitment and de-recruitment thresholds, as well as PIC magnitude calculated by a paired motor unit analysis were used to examine the neuromodulatory effects on discharge behaviours, such as minimum firing rate, peak firing rate and degree of increase in firing rate. Forty-two clearly identified motor units from five subjects revealed that soleus motor units are recruited progressively from rest to contraction strengths close to 95% of MVC, with low-threshold motor units discharging action potentials slower at their recruitment and with a lower peak rate than later recruited high-threshold units. This observation is in contrast to the 'onion skin phenomenon' often reported for the upper limb muscles. Based on positive correlations of the peak discharge rates, initial rates and recruitment order of the units with the magnitude of the onset-offset hysteresis and not PIC contribution, we conclude that discharge behaviours among motor units appear to be related to a variation in an intrinsic property other than PICs.

A novel carbon electrode material for highly improved EDLC performance.

PubMed

Fang, Baizeng; Binder, Leo

2006-04-20

Porous materials, developed by grafting functional groups through chemical surface modification with a surfactant, represent an innovative concept in energy storage. This work reports, in detail, the first practical realization of a novel carbon electrode based on grafting of vinyltrimethoxysilane (vtmos) functional group for energy storage in electric double layer capacitor (EDLC). Surface modification with surfactant vtmos enhances the hydrophobisation of activated carbon and the affinity toward propylene carbonate (PC) solvent, which improves the wettability of activated carbon in the electrolyte solution based on PC solvent, resulting in not only a lower resistance to the transport of electrolyte ions within micropores of activated carbon but also more usable surface area for the formation of electric double layer, and accordingly, higher specific capacitance, energy density, and power capability available from the capacitor based on modified carbon. Especially, the effects from surface modification become superior at higher discharge rate, at which much better EDLC performance (i.e., much higher energy density and power capability) has been achieved by the modified carbon, suggesting that the modified carbon is a novel and very promising electrode material of EDLC for large current applications where both high energy density and power capability are required.

One-step hydrothermal synthesis of 3D petal-like Co9S8/RGO/Ni3S2 composite on nickel foam for high-performance supercapacitors.

PubMed

Zhang, Zhuomin; Wang, Qian; Zhao, Chongjun; Min, Shudi; Qian, Xiuzhen

2015-03-04

Co9S8, Ni3S2, and reduced graphene oxide (RGO) were combined to construct a graphene composite with two mixed metal sulfide components. Co9S8/RGO/Ni3S2 composite films were hydrothermal-assisted synthesized on nickel foam (NF) by using a modified "active metal substrate" route in which nickel foam acted as both a substrate and Ni source for composite films. It is found that the Co9S8/RGO/Ni3S2/NF electrode exhibits superior capacitive performance with high capability (13.53 F cm(-2) at 20 mA cm(-2), i.e., 2611.9 F g(-1) at 3.9 A g(-1)), excellent rate capability, and enhanced electrochemical stability, with 91.7% retention after 1000 continuous charge-discharge cycles even at a high current density of 80 mA cm(-2).

NEXT Ion Thruster Performance Dispersion Analyses

NASA Technical Reports Server (NTRS)

Soulas, George C.; Patterson, Michael J.

2008-01-01

The NEXT ion thruster is a low specific mass, high performance thruster with a nominal throttling range of 0.5 to 7 kW. Numerous engineering model and one prototype model thrusters have been manufactured and tested. Of significant importance to propulsion system performance is thruster-to-thruster performance dispersions. This type of information can provide a bandwidth of expected performance variations both on a thruster and a component level. Knowledge of these dispersions can be used to more conservatively predict thruster service life capability and thruster performance for mission planning, facilitate future thruster performance comparisons, and verify power processor capabilities are compatible with the thruster design. This study compiles the test results of five engineering model thrusters and one flight-like thruster to determine unit-to-unit dispersions in thruster performance. Component level performance dispersion analyses will include discharge chamber voltages, currents, and losses; accelerator currents, electron backstreaming limits, and perveance limits; and neutralizer keeper and coupling voltages and the spot-to-plume mode transition flow rates. Thruster level performance dispersion analyses will include thrust efficiency.

Low temperature plasma synthesis of mesoporous Fe3O4 nanorods grafted on reduced graphene oxide for high performance lithium storage.

PubMed

Zhou, Quan; Zhao, Zongbin; Wang, Zhiyu; Dong, Yanfeng; Wang, Xuzhen; Gogotsi, Yury; Qiu, Jieshan

2014-02-21

Transition metal oxide coupling with carbon is an effective method for improving electrical conductivity of battery electrodes and avoiding the degradation of their lithium storage capability due to large volume expansion/contraction and severe particle aggregation during the lithium insertion and desertion process. In our present work, we develop an effective approach to fabricate the nanocomposites of porous rod-shaped Fe3O4 anchored on reduced graphene oxide (Fe3O4/rGO) by controlling the in situ nucleation and growth of β-FeOOH onto the graphene oxide (β-FeOOH/GO) and followed by dielectric barrier discharge (DBD) hydrogen plasma treatment. Such well-designed hierarchical nanostructures are beneficial for maximum utilization of electrochemically active matter in lithium ion batteries and display superior Li uptake with high reversible capacity, good rate capability, and excellent stability, maintaining 890 mA h g(-1) capacity over 100 cycles at a current density of 500 mA g(-1).

Electrochemical investigation of functionalized graphene aerogel with different amount of p-phenylenediamine as an advanced electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Gholipour-Ranjbar, Habib; Ganjali, Mohammad Reza; Norouzi, Parviz; Naderi, Hamid Reza

2016-07-01

Graphene aerogel has attracted great attention as a new and efficient electrode material for supercapacitors. It can be expected that functionalization of graphene aerogels can further improve their capability. In this study, graphene aerogel functionalized with different amount of p-phenylenediamine (PPD) and the effect of PPD amount on the supercapacitive performance of functionalized graphene aerogel (FGA) was investigated. Structural characterizations showed that PPD molecules initiated graphene aerogel sheets assembly into three-dimensional structures and also increasing PPD amount led to increase in surface area. Electrochemical investigations proved that the FGA with larger pore size showed enhanced supercapacitive performance compared with the FGA with smaller pore size. The optimized FGA-based electrode exhibited outstanding specific capacitance (SC) of 385 F g-1 at a discharge current density of 1 A g-1, good rate capability (215 F g-1 at 20 A g-1), and exceptionally high cyclic stability by displaying 25% increase in SC after 5000 cycle.

Investigation of lithium ion battery electrolytes containing flame retardants in combination with the film forming electrolyte additives vinylene carbonate, vinyl ethylene carbonate and fluoroethylene carbonate

NASA Astrophysics Data System (ADS)

Dagger, Tim; Grützke, Martin; Reichert, Matthias; Haetge, Jan; Nowak, Sascha; Winter, Martin; Schappacher, Falko M.

2017-12-01

In order to address the trade-off between the safety lithium ion battery (LIB) electrolytes and their electrochemical performance, synergetic effects of flame retardant additives (FRs) in combination with film forming additives (FFAs) are investigated. Triphenyl phosphate (TPP) and a silicon-containing additive (WA) are applied as FRs to improve the onset temperature of the thermal runaway of a LIB standard electrolyte (LP57: 1 M LiPF6 in EC:EMC 3:7) about 15 K and 28 K, respectively. The application of the FRs in MCMB graphite/lithium metal and NMC111/lithium metal three-electrode cells induces insufficiencies in terms of charge/discharge cycling stability and rate capability. It is investigated if the addition of FFAs can degrade the insufficiencies that are induced by the FRs. Vinylene carbonate, vinyl ethylene carbonate and fluoroethylene carbonate are added to a mixture of LP57 with 10% FR to enhance the cycling performance via improved interphase formation. Results reveal, that the rate capability of cells containing TPP or WA is especially improved by addition of 2% or 5% FEC, respectively. Postmortem analyses of the electrodes by SEM and of the electrolyte by GC-MS are performed. Direct correlations between the cycling behavior during the C-rate study and the electrolyte decomposition products are drawn.

Characteristics and time evolution of a hollow cathode produced glow discharge plasma in air

NASA Astrophysics Data System (ADS)

Gregor, Joseph Atilla

Current radar systems use mechanical directors and phased array technology for beam steering. Use of a sheet plasma as a microwave reflector promises several advantages over these methods. Operation is inherently broad-band, since all frequencies below the plasma frequency are reflected. The orientation and shape of the reflector may be changed directly through electronic control without resort to moving parts or expensive RF switches. The relatively fast plasma formation and extinction times ([/approx]10/ /mus) allow for rapid redirection of the microwave beam. An experimental system, dubbed the Agile Mirror, has been constructed using a cylindrical LexanTM vacuum chamber suspended within a water cooled Helmholtz coil pair capable of producing a uniform 500 Gauss field. Using this system we have created plasmas capable of reflecting 10 GHz microwaves with characteristics comparable to that of a plane metallic reflector. Most previous glow discharge work has concentrated either on the DC characteristics, or on the very early evolution (<1-2 μs), of the discharge. To create a practical agile mirror direction, we must be able to produce a stable, flat, homogeneous plasma sheet with predictable characteristics timescales from 5 μs to 1 ms-a regime where little pertinent quantitative data exists. This work concentrates on diagnosing the time resolved behavior of the agile mirror plasma during the mid-time, from t = 5-300 μs, in a regime which accentuates observed changes in the discharge circuit characteristics. Measurements on an air discharge produced using VD/approx2.2 kV, p ≈ 208 mTorr, and B ≈ 250 G reveal an ne=1011/ cm-3,/ Te=1[-]3 eV plasma with distinct negative glow, Faraday dark space, and positive column regions. Analysis of time resolved potential, temperature, and spectroscopic data reveal that this discharge transitions-on time scales of [/approx]100/ /mus-into a pure negative glow discharge. The characteristics and evolution of the discharge are highly reproducible. A computer model of the discharge reveals that heating of the background gas is responsible for the transition. Implications for operation of the agile mirror discharge as a plasma mirror are discussed.

Modeling of ESD events from polymeric surfaces

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

Pfeifer, Kent Bryant

2014-03-01

Transient electrostatic discharge (ESD) events are studied to assemble a predictive model of discharge from polymer surfaces. An analog circuit simulation is produced and its response is compared to various literature sources to explore its capabilities and limitations. Results suggest that polymer ESD events can be predicted to within an order of magnitude. These results compare well to empirical findings from other sources having similar reproducibility.

Field evaluation of boat-mounted acoustic Doppler instruments used to measure streamflow

USGS Publications Warehouse

Mueller, D.S.; ,

2003-01-01

The use of instruments based on the Doppler principle for measuring water velocity and computing discharge is common within the U.S. Geological Survey (USGS). The instruments and software have changed appreciably during the last 5 years; therefore, the USGS has begun field validation of the instruments used to make discharge measurements from a moving boat. Instruments manufactured by SonTek/YSI and RD Instruments, Inc. were used to collect discharge data at five different sites. One or more traditional discharge measurements were made using a Price AA current meter and standard USGS procedures concurrent with the acoustic instruments at each site. Discharges measured with the acoustic instruments were compared with discharges measured with Price AA current meters and the USGS stage-discharge rating for each site. The mean discharges measured by each acoustic instrument were within 5 percent of the Price AA-based measurement and (or) discharge from the stage-discharge rating.

Venous Thromboembolism-Related Readmission in Emergency General Surgery Patients: A Role for Prophylaxis on Discharge?

PubMed

DeWane, Michael P; Davis, Kimberly A; Schuster, Kevin M; Maung, Adrian A; Becher, Robert D

2018-06-01

Patients undergoing emergency general surgery (EGS) operations experience high rates of venous thromboembolism (VTE). The rates at which thrombus formation occurs after discharge, and whether VTE prophylaxis at discharge might be warranted to prevent readmission, are unknown. This analysis aimed to determine risk factors associated with VTE formation after discharge for EGS operations. An analysis of the American College of Surgeons NSQIP database from 2013 and 2014 of patients undergoing 10 common EGS operations in an emergent fashion. Multivariable logistic regression modeling was used to determine factors that predicted VTE after discharge. A total of 130,036 patients were included. The 30-day VTE rate was 1.30%, with 35% of all VTEs occurring after discharge. Of those who had VTE develop after discharge, 69.4% required readmission. Predictive factors for post-discharge VTE included prolonged length of stay (odds ratio [OR] 5.25; p < 0.001), presence of metastatic cancer (OR 2.23; p < 0.001), urinary tract infection (OR 1.91; p < 0.001), and postoperative sepsis (OR 1.55; p < 0.001). Identified high-risk groups had a rate of readmission with thrombus 6 times greater than that of average-risk EGS patients. More than 30% of VTEs in the EGS population occur after discharge; of these, a vast majority require readmission. Select high-risk EGS subgroups might benefit from prophylactic anticoagulation at discharge. Copyright © 2018 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Improvement of growth rate of plants by bubble discharge in water

NASA Astrophysics Data System (ADS)

Takahata, Junichiro; Takaki, Koichi; Satta, Naoya; Takahashi, Katsuyuki; Fujio, Takuya; Sasaki, Yuji

2015-01-01

The effect of bubble discharge in water on the growth rate of plants was investigated experimentally for application to plant cultivation systems. Spinach (Spinacia oleracea), radish (Raphanus sativus var. sativus), and strawberry (Fragaria × ananassa) were used as specimens to clarify the effect of the discharge treatment on edible parts of the plants. The specimens were cultivated in pots filled with artificial soil, which included chicken manure charcoal. Distilled water was sprayed on the artificial soil and drained through a hole in the pots to a water storage tank. The water was circulated from the water storage tank to the cultivation pots after 15 or 30 min discharge treatment on alternate days. A magnetic compression-type pulsed power generator was used to produce the bubble discharge with a repetition rate of 250 pps. The plant height in the growth phase and the dry weight of the harvested plants were improved markedly by the discharge treatment in water. The soil and plant analyzer development (SPAD) value of the plants also improved in the growth phase of the plants. The concentration of nitrate nitrogen, which mainly contributed to the improvement of the growth rate, in the water increased with the discharge treatment. The Brix value of edible parts of Fragaria × ananassa increased with the discharge treatment. The inactivation of bacteria in the water was also confirmed with the discharge treatment.

All dressed up but nowhere to go? Delayed hospital discharges and older people.

PubMed

Glasby, Jon; Littlechild, Rosemary; Pryce, Kathryn

2006-01-01

Delayed hospital discharges are a key concern in a number of industrialized nations and are the subject of a range of government initiatives in the English National Health Service. The aim of this paper was to review the UK literature on delayed hospital discharges and older people in order to identify and explore the rate and causes of delayed hospital discharges, together with policies and practices that may reduce delayed discharges and improve the experiences of older people. Literature review based on searches of major health/social-care databases. Sources which explore the rate and cause of delayed discharges in the UK were included. Relevant documents were categorized using the research hierarchy set out in the National Service Framework for Older People and analysed according to criteria for appraising the quality of qualitative research proposed by Mays et al. The review identified 21 studies, which suggest very different rates and causes of delayed discharge in different settings. The studies reveal the importance of rehabilitation services to reduce the rate of delayed discharge, the prevalence of delayed discharges caused by internal hospital factors, and the complex and multi-faceted nature of the factors contributing to delayed discharge. Despite this, the studies have a number of methodological flaws and often fail to include a patient perspective or to consider detailed policies and approaches to reduce the number of delayed discharges. There is also a failure to consider the needs of older people with mental health problems or people from minority ethnic communities. The evidence, as it currently stands, raises a number of issues about current hospital discharge policy, supporting some aspects of the current government agenda in England, but questioning other aspects.

Quality improvement through implementation of discharge order reconciliation.

PubMed

Lu, Yun; Clifford, Pamela; Bjorneby, Andreas; Thompson, Bruce; VanNorman, Samuel; Won, Katie; Larsen, Kevin

2013-05-01

A coordinated multidisciplinary process to reduce medication errors related to patient discharges to skilled-nursing facilities (SNFs) is described. After determining that medication errors were a frequent cause of readmission among patients discharged to SNFs, a medical center launched a two-phase quality-improvement project focused on cardiac and medical patients. Phase one of the project entailed a three-month failure modes and effects analysis of existing procedures discharge, followed by the development and pilot testing of a multidisciplinary, closed-loop workflow process involving staff and resident physicians, clinical nurse coordinators, and clinical pharmacists. During pilot testing of the new workflow process, the rate of discharge medication errors involving SNF patients was tracked, and data on medication-related readmissions in a designated intervention group (n = 87) and a control group of patients (n = 1893) discharged to SNFs via standard procedures during a nine-month period were collected, with the data stratified using severity of illness (SOI) classification. Analysis of the collected data indicated a cumulative 30-day medication-related readmission rate for study group patients in the minor, moderate, and major SOI categories of 5.4% (4 of 74 patients), compared with a rate of 9.5% (169 of 1780 patients) in the control group. In phase 2 of the project, the revised SNF discharge medication reconciliation procedure was implemented throughout the hospital; since hospitalwide implementation of the new workflow, the readmission rate for SNF patients has been maintained at about 6.7%. Implementing a standardized discharge order reconciliation process that includes pharmacists led to decreased readmission rates and improved care for patients discharged to SNFs.

High-energy lithium-ion hybrid supercapacitors composed of hierarchical urchin-like WO3/C anodes and MOF-derived polyhedral hollow carbon cathodes.

PubMed

Xu, Juan; Li, Yuanyuan; Wang, Lei; Cai, Qifa; Li, Qingwei; Gao, Biao; Zhang, Xuming; Huo, Kaifu; Chu, Paul K

2016-09-22

A lithium-ion hybrid supercapacitor (Li-HSC) comprising a Li-ion battery type anode and an electrochemical double layer capacitance (EDLC) type cathode has attracted much interest because it accomplishes a large energy density without compromising the power density. In this work, hierarchical carbon coated WO 3 (WO 3 /C) with a unique mesoporous structure and metal-organic framework derived nitrogen-doped carbon hollow polyhedra (MOF-NC) are prepared and adopted as the anode and the cathode for Li-HSCs. The hierarchical mesoporous WO 3 /C microspheres assembled by radially oriented WO 3 /C nanorods along the (001) plane enable effective Li + insertion, thus exhibit high capacity, excellent rate performance and a long cycling life due to their high Li + conductivity, electronic conductivity and structural robustness. The WO 3 /C structure shows a reversible specific capacity of 508 mA h g -1 at a 0.1 C rate (1 C = 696 mA h g -1 ) after 160 discharging-charging cycles with excellent rate capability. The MOF-NC achieved the specific capacity of 269.9 F g -1 at a current density of 0.2 A g -1 . At a high current density of 6 A g -1 , 92.4% of the initial capacity could be retained after 2000 discharging-charging cycles, suggesting excellent cycle stability. The Li-HSC comprising a WO 3 /C anode and a MOF-NC cathode boasts a large energy density of 159.97 W h kg -1 at a power density of 173.6 W kg -1 and 88.3% of the capacity is retained at a current density of 5 A g -1 after 3000 charging-discharging cycles, which are better than those previously reported for Li-HSCs. The high energy and power densities of the Li-HSCs of WO 3 /C//MOF-NC render large potential in energy storage.

Nanoporous TiNb2O7/C Composite Microspheres with Three-Dimensional Conductive Network for Long-Cycle-Life and High-Rate-Capability Anode Materials for Lithium-Ion Batteries.

PubMed

Zhu, Guozhen; Li, Qing; Zhao, Yunhao; Che, Renchao

2017-11-29

On the basis of the advantages of ideal cycling stability, high discharge voltage (1.65 V), and excellent reversibility, more and more attention has been focused on TiNb 2 O 7 (marked as TNO) as an anode material candidate for lithium-ion batteries. However, the poor electronic conductivity and low ionic diffusion rate intrinsically restrict its practical use. Herein, we first synthesize the TNO/C composite microspheres with three-dimensionally (marked as 3D) electro-conductive carbon network and abundant nanoporous structure by a simple spray-drying method. The microspheres are constructed by irregularly primary cubic nanoparticle units with size of 100-200 nm. The nanopores throughout the microspheres range from 1 to 50 nm. As an anode material, the prepared TNO/C composite microspheres demonstrate a prominent charge/discharge capacity of 323.2/326 mA h g -1 after 300 cycles at 0.25 C (1 C = 388 mA g -1 ) and 259.9/262.5 mA h g -1 after 1000 long cycles at a high current density of 5 C, revealing the ideal reversible capacity and long cycling life. Meanwhile, the TNO/C composite microspheres present ideal rate performance, showing the discharge capacity of 120 mA h g -1 at 30 C after 10 cycles. The super electrochemical performance could be attributed to the 3D electro-conductive carbon network and nanoporous structure. The nanopores facilitate the permeation of electrolyte into the intercontacting regions of the anode materials. Carbon layers disperse uniformly throughout the 3D microspheres, effectively improving the electrical conductivity of the electrode. Hence, the prepared TNO/C composite microspheres have great potential to be used as an anode material for lithium-ion batteries.

The flow structure of jets from transient sources and implications for modeling short-duration explosive volcanic eruptions

NASA Astrophysics Data System (ADS)

Chojnicki, K. N.; Clarke, A. B.; Adrian, R. J.; Phillips, J. C.

2014-12-01

We used laboratory experiments to examine the rise process in neutrally buoyant jets that resulted from an unsteady supply of momentum, a condition that defines plumes from discrete Vulcanian and Strombolian-style eruptions. We simultaneously measured the analog-jet discharge rate (the supply rate of momentum) and the analog-jet internal velocity distribution (a consequence of momentum transport and dilution). Then, we examined the changes in the analog-jet velocity distribution over time to assess the impact of the supply-rate variations on the momentum-driven rise dynamics. We found that the analog-jet velocity distribution changes significantly and quickly as the supply rate varied, such that the whole-field distribution at any instant differed considerably from the time average. We also found that entrainment varied in space and over time with instantaneous entrainment coefficient values ranging from 0 to 0.93 in an individual unsteady jet. Consequently, we conclude that supply-rate variations exert first-order control over jet dynamics, and therefore cannot be neglected in models without compromising their capability to predict large-scale eruption behavior. These findings emphasize the fundamental differences between unsteady and steady jet dynamics, and show clearly that: (i) variations in source momentum flux directly control the dynamics of the resulting flow; (ii) impulsive flows driven by sources of varying flux cannot reasonably be approximated by quasi-steady flow models. New modeling approaches capable of describing the time-dependent properties of transient volcanic eruption plumes are needed before their trajectory, dilution, and stability can be reliably computed for hazards management.

Phosphoric acid as an electrolyte additive for lead/acid batteries in electric-vehicle applications

NASA Astrophysics Data System (ADS)

Meissner, E.

The influence of the addition of phosphoric acid to the electrolyte on the performance of gelled lead/acid electric-vehiicle batteries is investigated. This additive reduces the reversible capacity decay of the positive electrode significantly which is observed upon extended cycling when recharge of the battery is performed at low initial rate. This is important when low-rate on-board chargers are used. Pulsed discharge, typical for electric-vehicle application, induces reversible capacity decay more than constant-current discharge at a same depth-of-discharge, as well with as without the addition of phosphoric acid. By contrast, hindrance in presence of H 3PO 4 for both the recharge and the discharge reaction helps to homogenize the state of many individual cells during cycling in long battery strings. Reversible capacity loss, which occurs after extended cycling and when pulsed discharge is applied, can be recovered by a single discharge at very low rate with batteries with and without the addition of phosphoric acid. The discharge-rate dependency of the capacity is significantly reduced when phosphoric acid is added. The pulse discharge behaviour may be better, even if the nominal capacity is reduced. The experimental findings of the influence of phosphoric acid addition is discussed in terms of the aggregate-of-spheres model of reversible capacity decay.

Modeling daily discharge responses of a large karstic aquifer using soft computing methods: Artificial neural network and neuro-fuzzy

NASA Astrophysics Data System (ADS)

Kurtulus, Bedri; Razack, Moumtaz

2010-02-01

SummaryThis paper compares two methods for modeling karst aquifers, which are heterogeneous, highly non-linear, and hierarchical systems. There is a clear need to model these systems given the crucial role they play in water supply in many countries. In recent years, the main components of soft computing (fuzzy logic (FL), and Artificial Neural Networks, (ANNs)) have come to prevail in the modeling of complex non-linear systems in different scientific and technologic disciplines. In this study, Artificial Neural Networks and Adaptive Neuro-Fuzzy Interface System (ANFIS) methods were used for the prediction of daily discharge of karstic aquifers and their capability was compared. The approach was applied to 7 years of daily data of La Rochefoucauld karst system in south-western France. In order to predict the karst daily discharges, single-input (rainfall, piezometric level) vs. multiple-input (rainfall and piezometric level) series were used. In addition to these inputs, all models used measured or simulated discharges from the previous days with a specified delay. The models were designed in a Matlab™ environment. An automatic procedure was used to select the best calibrated models. Daily discharge predictions were then performed using the calibrated models. Comparing predicted and observed hydrographs indicates that both models (ANN and ANFIS) provide close predictions of the karst daily discharges. The summary statistics of both series (observed and predicted daily discharges) are comparable. The performance of both models is improved when the number of inputs is increased from one to two. The root mean square error between the observed and predicted series reaches a minimum for two-input models. However, the ANFIS model demonstrates a better performance than the ANN model to predict peak flow. The ANFIS approach demonstrates a better generalization capability and slightly higher performance than the ANN, especially for peak discharges.

Performance and Thermal Characterization of the NASA-300MS 20 kW Hall Effect Thruster

NASA Technical Reports Server (NTRS)

Kamhawi, Hani; Huang, Wensheng; Haag, Thomas; Shastry, Rohit; Soulas, George; Smith, Timothy; Mikellides, Ioannis; Hofer, Richard

2013-01-01

NASA's Space Technology Mission Directorate is sponsoring the development of a high fidelity 15 kW-class long-life high performance Hall thruster for candidate NASA technology demonstration missions. An essential element of the development process is demonstration that incorporation of magnetic shielding on a 20 kW-class Hall thruster will yield significant improvements in the throughput capability of the thruster without any significant reduction in thruster performance. As such, NASA Glenn Research Center and the Jet Propulsion Laboratory collaborated on modifying the NASA-300M 20 kW Hall thruster to improve its propellant throughput capability. JPL and NASA Glenn researchers performed plasma numerical simulations with JPL's Hall2De and a commercially available magnetic modeling code that indicated significant enhancement in the throughput capability of the NASA-300M can be attained by modifying the thruster's magnetic circuit. This led to modifying the NASA-300M magnetic topology to a magnetically shielded topology. This paper presents performance evaluation results of the two NASA-300M magnetically shielded thruster configurations, designated 300MS and 300MS-2. The 300MS and 300MS-2 were operated at power levels between 2.5 and 20 kW at discharge voltages between 200 and 700 V. Discharge channel deposition from back-sputtered facility wall flux, and plasma potential and electron temperature measurements made on the inner and outer discharge channel surfaces confirmed that magnetic shielding was achieved. Peak total thrust efficiency of 64% and total specific impulse of 3,050 sec were demonstrated with the 300MS-2 at 20 kW. Thermal characterization results indicate that the boron nitride discharge chamber walls temperatures are approximately 100 C lower for the 300MS when compared to the NASA- 300M at the same thruster operating discharge power.

Rate-dependent, Li-ion insertion/deinsertion behavior of LiFePO4 cathodes in commercial 18650 LiFePO4 cells.

PubMed

Liu, Qi; He, Hao; Li, Zhe-Fei; Liu, Yadong; Ren, Yang; Lu, Wenquan; Lu, Jun; Stach, Eric A; Xie, Jian

2014-03-12

We have performed operando synchrotron high-energy X-ray diffraction (XRD) to obtain nonintrusive, real-time monitoring of the dynamic chemical and structural changes in commercial 18650 LiFePO4/C cells under realistic cycling conditions. The results indicate a nonequilibrium lithium insertion and extraction in the LiFePO4 cathode, with neither the LiFePO4 phase nor the FePO4 phase maintaining a static composition during lithium insertion/extraction. On the basis of our observations, we propose that the LiFePO4 cathode simultaneously experiences both a two-phase reaction mechanism and a dual-phase solid-solution reaction mechanism over the entire range of the flat voltage plateau, with this dual-phase solid-solution behavior being strongly dependent on charge/discharge rates. The proposed dual-phase solid-solution mechanism may explain the remarkable rate capability of LiFePO4 in commercial cells.

Bulk antimony sulfide with excellent cycle stability as next-generation anode for lithium-ion batteries

PubMed Central

Yu, Denis Y. W.; Hoster, Harry E.; Batabyal, Sudip K.

2014-01-01

Nanomaterials as anode for lithium-ion batteries (LIB) have gained widespread interest in the research community. However, scaling up and processibility are bottlenecks to further commercialization of these materials. Here, we report that bulk antimony sulfide with a size of 10–20 μm exhibits a high capacity and stable cycling of 800 mAh g−1. Mechanical and chemical stabilities of the electrodes are ensured by an optimal electrode-electrolyte system design, with a polyimide-based binder together with fluoroethylene carbonate in the electrolyte. The polyimide binder accommodates the volume expansion during alloying process and fluoroethylene carbonate suppresses the increase in charge transfer resistance of the electrodes. We observed that particle size is not a major factor affecting the charge-discharge capacities, rate capability and stability of the material. Despite the large particle size, bulk antimony sulfide shows excellent rate performance with a capacity of 580 mAh g−1 at a rate of 2000 mA g−1. PMID:24691396

A Sugar-Derived Room-Temperature Sodium Sulfur Battery with Long Term Cycling Stability.

PubMed

Carter, Rachel; Oakes, Landon; Douglas, Anna; Muralidharan, Nitin; Cohn, Adam P; Pint, Cary L

2017-03-08

We demonstrate a room-temperature sodium sulfur battery based on a confining microporous carbon template derived from sucrose that delivers a reversible capacity over 700 mAh/g S at 0.1C rates, maintaining 370 mAh/g S at 10 times higher rates of 1C. Cycling at 1C rates reveals retention of over 300 mAh/g S capacity across 1500 cycles with Coulombic efficiency >98% due to microporous sulfur confinement and stability of the sodium metal anode in a glyme-based electrolyte. We show sucrose to be an ideal platform to develop microporous carbon capable of mitigating electrode-electrolyte reactivity and loss of soluble intermediate discharge products. In a manner parallel to the low-cost materials of the traditional sodium beta battery, our work demonstrates the combination of table sugar, sulfur, and sodium, all of which are cheap and earth abundant, for a high-performance stable room-temperature sodium sulfur battery.

Noncovalently-functionalized reduced graphene oxide sheets by water-soluble methyl green for supercapacitor application

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

Ren, Xiaoying; Hu, Zhongai, E-mail: zhongai@nwnu.edu.cn; Hu, Haixiong

2015-10-15

Graphical abstract: Electroactive methyl green (MG) is selected to functionalize reduced graphene oxide (RGO) through non-covalent modification and the composite achieves high specific capacitance, good rate capability and excellent long life cycle. - Highlights: • MG–RGO composites were firstly prepared through non-covalent modification. • The mass ratio in composites is a key for achieving high specific capacitance. • MG–RGO 5:4 exhibits the highest specific capacitance of 341 F g{sup −1}. • MG–RGO 5:4 shows excellent rate capability and long life cycle. - Abstract: In the present work, water-soluble electroactive methyl green (MG) has been used to non-covalently functionalize reduced graphenemore » oxide (RGO) for enhancing supercapacitive performance. The microstructure, composition and morphology of MG–RGO composites are systematically characterized by UV–vis absorption, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical performances are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). The fast redox reactions from MG could generate additional pseudocapacitance, which endows RGO higher capacitances. As a result, the MG–RGO composite (with the 5:4 mass ratio of MG:RGO) achieve a maximum value of 341 F g{sup −1} at 1 A g{sup −1} within the potential range from −0.25 to 0.75 V and provide a 180% enhancement in specific capacitance in comparison with pure RGO. Furthermore, excellent rate capability (72% capacitance retention from 1 A g{sup −1} to 20 A g{sup −1}) and long life cycle (12% capacitance decay after 5000 cycles) are achieved for the MG–RGO composite electrode.« less

Cobalt Disulfide Nanoparticles Embedded in Porous Carbonaceous Micro-Polyhedrons Interlinked by Carbon Nanotubes for Superior Lithium and Sodium Storage.

PubMed

Ma, Yuan; Ma, Yanjiao; Bresser, Dominic; Ji, Yuanchun; Geiger, Dorin; Kaiser, Ute; Streb, Carsten; Varzi, Alberto; Passerini, Stefano

2018-06-27

Transition metal sulfides are appealing electrode materials for lithium and sodium batteries owing to their high theoretical capacity. However, they are commonly characterized by rather poor cycling stability and low rate capability. Herein, we investigate CoS 2 , serving as a model compound. We synthesized a porous CoS 2 /C micro-polyhedron composite entangled in a carbon-nanotube-based network (CoS 2 -C/CNT), starting from zeolitic imidazolate frameworks-67 as a single precursor. Following an efficient two-step synthesis strategy, the obtained CoS 2 nanoparticles are uniformly embedded in porous carbonaceous micro-polyhedrons, interwoven with CNTs to ensure high electronic conductivity. The CoS 2 -C/CNT nanocomposite provides excellent bifunctional energy storage performance, delivering 1030 mAh g -1 after 120 cycles and 403 mAh g -1 after 200 cycles (at 100 mA g -1 ) as electrode for lithium-ion (LIBs) and sodium-ion batteries (SIBs), respectively. In addition to these high capacities, the electrodes show outstanding rate capability and excellent long-term cycling stability with a capacity retention of 80% after 500 cycles for LIBs and 90% after 200 cycles for SIBs. In situ X-ray diffraction reveals a significant contribution of the partially graphitized carbon to the lithium and at least in part also for the sodium storage and the report of a two-step conversion reaction mechanism of CoS 2 , eventually forming metallic Co and Li 2 S/Na 2 S. Particularly the lithium storage capability at elevated (dis-)charge rates, however, appears to be substantially pseudocapacitive, thus benefiting from the highly porous nature of the nanocomposite.

Lunabotics Mining: Evolution of ARTEMIS PRIME

NASA Technical Reports Server (NTRS)

Bertke, Sarah; Gries, Christine; Huff, Amanda; Logan, Brittany; Oliver, Kaitlin; Rigney, Erica; Tyree, Whitney; Young, Maegan

2010-01-01

This slide presentation reviews the development of Amassing Regolith with Topper Engineers eMploying Innovative Solutions (ARTEMIS) in a competition to develop robotic lunar mining capabilities. The goal of the competition was to design, build and operate a remotely controlled device that is capable of excavating, transporting and discharging lunar regolith simulant in a lunar environment over a 13 minute period.

Performance and Abuse Testing of 5 Year Old Low Rate and Medium Rate Lithium Thionyl Chloride Cells

NASA Technical Reports Server (NTRS)

Frerker, Rick; Zhang, Wenlin; Jeevarajan, Judith; Bragg, Bobby J.

2001-01-01

Most cells survived the 3 amp (A) over-discharge at room temperature for 2 hours. The cell that failed was the LTC-114 after high rate discharge of 500 mA similar to the results of the 1 A over-discharge test. Most cells opened during 0.05 Ohm short circuit test without incident but three LTC-111 cells exploded apparently due to a lack of a thermal cutoff switch. The LTC-114 cells exposed to a hard short of 0.05 Ohms recovered but the LTC-114 cells exposed to a soft short of 1 Ohm did not. This is probably due to the activation of a resetable fuse during a hard short. Fresh cells tend to survive exposure to higher temperatures than cells previously discharged at high rate (1 Amp). LTC-111 cells tend to vent at lower temperatures than the all LTC-114 cells and the LTC-115 cells that were previously discharged at rates exceeding 1 Amp.

Discharge variability and bedrock river incision on the Hawaiian island of Kaua'i

NASA Astrophysics Data System (ADS)

Huppert, K.; Deal, E.; Perron, J. T.; Ferrier, K.; Braun, J.

2017-12-01

Bedrock river incision occurs during floods that generate sufficient shear stress to strip riverbeds of sediment cover and erode underlying bedrock. Thresholds for incision can prevent erosion at low flows and slow down erosion at higher flows that do generate excess shear stress. Because discharge distributions typically display power-law tails, with non-negligible frequencies of floods much greater than the mean, models incorporating stochastic discharge and incision thresholds predict that discharge variability can sometimes have greater effects on long-term incision rates than mean discharge. This occurs when the commonly observed inverse scalings between mean discharge and discharge variability are weak or when incision thresholds are high. Because the effects of thresholds and discharge variability have only been documented in a few locations, their influence on long-term river incision rates remains uncertain. The Hawaiian island of Kaua'i provides an ideal natural laboratory to evaluate the effects of discharge variability and thresholds on bedrock river incision because it has one of Earth's steepest spatial gradients in mean annual rainfall and it also experiences dramatic spatial variations in rainfall and discharge variability, spanning a wide range of the conditions reported on Earth. Kaua'i otherwise has minimal variations in lithology, vertical motion, and other factors that can influence erosion. River incision rates averaged over 1.5 - 4.5 Myr timescales can be estimated along the lengths of Kauaian channels from the depths of river canyons and lava flow ages. We characterize rainfall and discharge variability on Kaua'i using records from an extensive network of rain and stream gauges spanning the past century. We use these characterizations to model long-term bedrock river incision along Kauaian channels with a threshold-dependent incision law, modulated by site-specific discharge-channel width scalings. Our comparisons between modeled and observed erosion rates suggest that variations in river incision rates on Kaua'i are dominated by variations in mean rainfall and discharge, rather than by differences in storminess across the island. We explore the implications of this result for the threshold dependence of river incision across Earth's varied climates.

Supercapacitors based on self-assembled graphene organogel.

PubMed

Sun, Yiqing; Wu, Qiong; Shi, Gaoquan

2011-10-14

Self-assembled graphene organogel (SGO) with 3-dimensional (3D) macrostructure was prepared by solvothermal reduction of a graphene oxide (GO) dispersion in propylene carbonate (PC). This SGO was used as an electrode material for fabricating supercapacitors with a PC electrolyte. The supercapacitor can be operated in a wide voltage range of 0-3 V and exhibits a high specific capacitance of 140 F g(-1) at a discharge current density of 1 A g(-1). Furthermore, it can still keep a specific capacitance of 90 F g(-1) at a high current density of 30 A g(-1). The maximum energy density of the SGO based supercapacitor was tested to be 43.5 Wh kg(-1), and this value is higher than those of the graphene based supercapacitors with aqueous or PC electrolytes reported previously. Furthermore, at a high discharge current density of 30 A g(-1), the energy and power densities of the supercapacitor were measured to be 15.4 Wh kg(-1) and 16,300 W kg(-1), respectively. These results indicate that the supercapacitor has a high specific capacitance and power density, and excellent rate capability.

Heterogeneous NiCo2O4@polypyrrole core/sheath nanowire arrays on Ni foam for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Hu, Jing; Li, Minchan; Lv, Fucong; Yang, Mingyang; Tao, Pengpeng; Tang, Yougen; Liu, Hongtao; Lu, Zhouguang

2015-10-01

A novel heterogeneous NiCo2O4@PPy core/sheath nanowire arrays are directly grown on Ni foam involving three facile steps, hydrothermal synthesis and calcination of NiCo2O4 nanowire arrays and subsequent in-situ oxidative polymerization of polypyrrole (PPy). When investigated as binder- and conductive additive-free electrodes for supercapacitors (SCs) in 6 M KOH, the NiCo2O4@PPy core/sheath nanowire arrays exhibit high areal capacitance of 3.49 F cm-2 at a discharge current density of 5 mA cm-2, which is almost 1.5 times as much as the pristine NiCo2O4 (2.30 F cm-2). More importantly, it can remain 3.31 F cm-2 (94.8% retention) after 5000 cycles. The as-obtained electrode also displays excellent rate capability, whose areal capacitance can still remain 2.79 F cm-2 while the discharge current density is increased to 50 mA cm-2. The remarkable electrochemical performance is mainly attributed to the unique heterogeneous core/sheath nanowire-array architectures.

Bioinspired Carbon/SnO2 Composite Anodes Prepared from a Photonic Hierarchical Structure for Lithium Batteries.

PubMed

Li, Yao; Meng, Qing; Ma, Jun; Zhu, Chengling; Cui, Jingru; Chen, Zhixin; Guo, Zaiping; Zhang, Tao; Zhu, Shenmin; Zhang, Di

2015-06-03

A carbon/SnO2 composite (C-SnO2) with hierarchical photonic structure was fabricated from the templates of butterfly wings. We have investigated for the first time its application as the anode material for lithium-ion batteries. It was demonstrated to have high reversible capacities, good cycling stability, and excellent high-rate discharge performance, as shown by a capacitance of ∼572 mAh g(-1) after 100 cycles, 4.18 times that of commercial SnO2 powder (137 mAh g(-1)); a far better recovery capability of 94.3% was observed after a step-increase and sudden-recovery current. An obvious synergistic effect was found between the porous, hierarchically photonic microstructure and the presence of carbon; the synergy guarantees an effective flow of electrolyte and a short diffusion length of lithium ions, provides considerable buffering room, and prevents aggregation of SnO2 particles in the discharge/charge processes. This nature-inspired strategy points out a new direction for the fabrication of alternative anode materials.

Calcium-bismuth electrodes for large-scale energy storage (liquid metal batteries)

NASA Astrophysics Data System (ADS)

Kim, Hojong; Boysen, Dane A.; Ouchi, Takanari; Sadoway, Donald R.

2013-11-01

Calcium is an attractive electrode material for use in grid-scale electrochemical energy storage due to its low electronegativity, earth abundance, and low cost. The feasibility of combining a liquid Ca-Bi positive electrode with a molten salt electrolyte for use in liquid metal batteries at 500-700 °C was investigated. Exhibiting excellent reversibility up to current densities of 200 mA cm-2, the calcium-bismuth liquid alloy system is a promising positive electrode candidate for liquid metal batteries. The measurement of low self-discharge current suggests that the solubility of calcium metal in molten salt electrolytes can be sufficiently suppressed to yield high coulombic efficiencies >98%. The mechanisms giving rise to Ca-Bi electrode overpotentials were investigated in terms of associated charge transfer and mass transport resistances. The formation of low density Ca11Bi10 intermetallics at the electrode-electrolyte interface limited the calcium deposition rate capability of the electrodes; however, the co-deposition of barium into bismuth from barium-containing molten salts suppressed Ca-Bi intermetallic formation thereby improving the discharge capacity.

MnO2/carbon nanowalls composite electrode for supercapacitor application

NASA Astrophysics Data System (ADS)

Hassan, Sameh; Suzuki, Masaaki; Mori, Shinsuke; El-Moneim, Ahmed Abd

2014-03-01

Amorphous MnO2/carbon nanowalls composite films are developed for the supercapacitor applications. Synthesis of carbon nanowalls template is performed by plasma-enhanced chemical vapor deposition in a CO/H2 microwave discharge system. A well dispersion of amorphous MnO2 domains throughout carbon nanowalls template is obtained by potentiostatic anodic deposition technique. Carbon nanowalls enable to improve the capacitive behavior and rate capability of MnO2, a specific capacitance of 851 F g-1 at a current density of 1 mA cm-2 and charge transfer resistance of 1.02 Ω are obtained. MnO2/carbon nanowalls composite film exhibits energy density of 118 wh kg-1, power density of 783 wh kg-1, and capacitance retention of 92% after long cycle life of 2000 cycles by charging and discharging at 3 mA cm-2. The high density of atomic scale graphitic edges and large surface area of carbon nanowalls in conjunction with the presence of amorphous MnO2 domains facilitate rapid electron and ion transport and hence offering the potential of the improved capacitive behavior.

An in situ generated carbon as integrated conductive additive for hierarchical negative plate of lead-acid battery

NASA Astrophysics Data System (ADS)

Saravanan, M.; Ganesan, M.; Ambalavanan, S.

2014-04-01

In this work, we report an in situ generated carbon from sugar as additive in the Negative Active Mass (NAM) which enhances the charge-discharge characteristics of the lead-acid cells. In situ formed sugar derived carbon (SDC) with leady oxide (LO) provides a conductive network and excellent protection against NAM irreversible lead sulfation. The effect of SDC and carbon black (CB) added negative plates are characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), galvanostatic charge-discharge, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. The results show that subtle changes in the addition of carbon to NAM led to subsequent changes on the performance during partial-state-of-charge (PSoC) operations in lead-acid cells. Furthermore, SDC added cells exhibit remarkable improvement in the rate capability, active material utilization, cycle performance and charge acceptance compared to that of the conventional CB added cells. The impact of SDC with LO at various synthesis conditions on the electrochemical performance of the negative plate is studied systematically.

Automatic dilution gaging of rapidly varying flow

USGS Publications Warehouse

Duerk, M.D.

1983-01-01

The analysis showed that the discharges measured by dye-dilution techniques were generally within ± 10 percent of the discharges determined from ratings established by current-meter measurements. Larger differences were noted at the start of and on the rising limb of four hydrographs. Of the 20 storms monitored, dilution measurements on 17 were of acceptable accuracy. Peak discharges from the open-channel site ranged from 0 to 12 percent departures from the existing rating whereas the comparison of peak discharge at the storm sewer site ranged from 0 to 5 percent departures from the existing rating.

Preparation and Rate Capability of Carbon Coated LiNi1/3Co1/3Mn1/3O2 as Cathode Material in Lithium Ion Batteries.

PubMed

Yang, Chaofan; Zhang, Xiaosong; Huang, Mengyi; Huang, Junjie; Fang, Zebo

2017-04-12

LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM) is regarded as a promising material for next-generation lithium ion batteries due to the high capacity, but its practical applications are limited by the poor electronic conductivity. Here, a one-step method is used to prepare carbon coated LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM/C) by applying active carbon as reaction matrix. TEM shows LiNi 1/3 Co 1/3 Mn 1/3 O 2 particles are homogeneously coated by carbon with a thickness about 10 nm. NCM/C delivers the discharge capacity of 191.2 mAh g -1 at 0.5 C (85 mA g -1 ) with a columbic efficiency of 91.1%. At 40 C (6800 mA g -1 ), the discharge capacity of NCM/C is 54.6 mAh g -1 , whereas NCM prepared through sol-gel route only delivers 13.2 mAh g -1 . After 100 charge and discharge cycles at 1 C (170 mA g -1 ) the capacity retention is 90.3% for NCM/C, whereas it is only 72.4% for NCM. The superior charge/discharge performance of NCM/C owes much to the carbon coating layer, which is not only helpful to increase the electronic conductivity but also contributive to inhibit the side reactions between LiNi 1/3 Co 1/3 Mn 1/3 O 2 and the liquid electrolyte.

Commercial expanded graphite as a low-cost, long-cycling life anode for potassium-ion batteries with conventional carbonate electrolyte

NASA Astrophysics Data System (ADS)

An, Yongling; Fei, Huifang; Zeng, Guifang; Ci, Lijie; Xi, Baojuan; Xiong, Shenglin; Feng, Jinkui

2018-02-01

Design and synthesis of capable anode materials that can store the large size K+ is the key of development for potassium-ion batteries. The low-cost and commercial expanded graphite with large particles is a graphite-derived material with good conductivity and enlarged interlayer spaces to boost the potassium ion diffusion coefficient during charge/discharge process. Thus, we achieve excellent anode performance for potassium-ion batteries based on an expanded graphite. It can deliver a capacity of 263 mAh g-1 at the rate of 10 mA g-1 and the reversible capacity remains almost unchanged after 500 cycles at a high rate of 200 mA g-1 with a coulombic efficiency of around 100%. The potassium storage mechanism is investigated by the ex situ XRD technique. This excellent potassium storage performance will make the expanded graphite promising anode candidate for potassium ion batteries.

Hierarchical LiFePO4 with a controllable growth of the (010) facet for lithium-ion batteries.

PubMed

Guo, Binbin; Ruan, Hongcheng; Zheng, Cheng; Fei, Hailong; Wei, Mingdeng

2013-09-27

Hierarchically structured LiFePO4 was successfully synthesized by ionic liquid solvothermal method. These hierarchically structured LiFePO4 samples were constructed from nanostructured platelets with their (010) facets mainly exposed. To the best of our knowledge, facet control of a hierarchical LiFePO4 crystal has not been reported yet. Based on a series of experimental results, a tentative mechanism for the formation of these hierarchical structures was proposed. After these hierarchically structured LiFePO4 samples were coated with a thin carbon layer and used as cathode materials for lithium-ion batteries, they exhibited excellent high-rate discharge capability and cycling stability. For instance, a capacity of 95% can be maintained for the LiFePO4 sample at a rate as high as 20 C, even after 1000 cycles.

Controllable synthesis, morphology evolution and electrochemical properties of LiFePO4 cathode materials for Li-ion batteries.

PubMed

Song, Jianjun; Wang, Lin; Shao, Guangjie; Shi, Meiwu; Ma, Zhipeng; Wang, Guiling; Song, Wei; Liu, Shuang; Wang, Caixia

2014-05-07

Monodispersed LiFePO4 nanocrystals with diverse morphologies were successfully synthesized via a mild and controllable solvothermal approach with a mixture of ethylene glycol and oleic acid as the solvent. Morphology evolution of LiFePO4 nanoparticles from nanoplates to nanorods can be simply realized by varying the volume ratio of oleic acid to ethylene glycol. Moreover, the mechanism of competitive adsorption between ethylene glycol and oleic acid was proposed for the formation of different morphologies. Electrochemical measurements show that the LiFePO4/C nanorods have an initial discharge capacity of 155 mA h g(-1) at 0.5 C with a capacity retention of 80% at a high rate of 5 C, which confirms that LiFePO4/C nanorods exhibit excellent rate capability and cycling stability.

Flagellar filament bio-templated inorganic oxide materials - towards an efficient lithium battery anode.

PubMed

Beznosov, Sergei N; Veluri, Pavan S; Pyatibratov, Mikhail G; Chatterjee, Abhijit; MacFarlane, Douglas R; Fedorov, Oleg V; Mitra, Sagar

2015-01-13

Designing a new generation of energy-intensive and sustainable electrode materials for batteries to power a variety of applications is an imperative task. The use of biomaterials as a nanosized structural template for these materials has the potential to produce hitherto unachievable structures. In this report, we have used genetically modified flagellar filaments of the extremely halophilic archaea species Halobacterium salinarum to synthesize nanostructured iron oxide composites for use as a lithium-ion battery anode. The electrode demonstrated a superior electrochemical performance compared to existing literature results, with good capacity retention of 1032 mAh g(-1) after 50 cycles and with high rate capability, delivering 770 mAh g(-1) at 5 A g(-1) (~5 C) discharge rate. This unique flagellar filament based template has the potential to provide access to other highly structured advanced energy materials in the future.

High-capacity FeTiO3/C negative electrode for sodium-ion batteries with ultralong cycle life

NASA Astrophysics Data System (ADS)

Ding, Changsheng; Nohira, Toshiyuki; Hagiwara, Rika

2018-06-01

The development of electrode materials which improve both the energy density and cycle life is one of the most challenging issues facing the practical application of sodium-ion batteries today. In this work, FeTiO3/C nanoparticles are synthesized as negative electrode materials for sodium-ion batteries. The electrochemical performance and charge-discharge mechanism of the FeTiO3/C negative electrode are investigated in an ionic liquid electrolyte at 90 °C. The FeTiO3/C negative electrode delivers a high reversible capacity of 403 mAh g-1 at a current rate of 10 mA g-1, and exhibits high rate capability and excellent cycling stability for up to 2000 cycles. The results indicate that FeTiO3/C is a promising negative electrode material for sodium-ion batteries.

Flagellar filament bio-templated inorganic oxide materials – towards an efficient lithium battery anode

PubMed Central

Beznosov, Sergei N.; Veluri, Pavan S.; Pyatibratov, Mikhail G.; Chatterjee, Abhijit; MacFarlane, Douglas R.; Fedorov, Oleg V.; Mitra, Sagar

2015-01-01

Designing a new generation of energy-intensive and sustainable electrode materials for batteries to power a variety of applications is an imperative task. The use of biomaterials as a nanosized structural template for these materials has the potential to produce hitherto unachievable structures. In this report, we have used genetically modified flagellar filaments of the extremely halophilic archaea species Halobacterium salinarum to synthesize nanostructured iron oxide composites for use as a lithium-ion battery anode. The electrode demonstrated a superior electrochemical performance compared to existing literature results, with good capacity retention of 1032 mAh g−1 after 50 cycles and with high rate capability, delivering 770 mAh g−1 at 5 A g−1 (~5 C) discharge rate. This unique flagellar filament based template has the potential to provide access to other highly structured advanced energy materials in the future. PMID:25583370

A nanoporous metal recuperated MnO2 anode for lithium ion batteries.

PubMed

Guo, Xianwei; Han, Jiuhui; Zhang, Ling; Liu, Pan; Hirata, Akihiko; Chen, Luyang; Fujita, Takeshi; Chen, Mingwei

2015-10-07

Lithium-ion batteries (LIBs) have been intensively studied to meet the increased demands for the high energy density of portable electronics and electric vehicles. The low specific capacity of the conventional graphite based anodes is one of the key factors that limit the capacity of LIBs. Transition metal oxides, such as NiO, MnO2 and Fe3O4, are known to be promising anode materials that are expected to improve the specific capacities of LIBs for several times. However, the poor electrical conductivity of these oxides significantly restricts the lithium ion storage and charge/discharge rate. Here we report that dealloyed nanoporous metals can realize the intrinsic lithium storage performance of the oxides by forming oxide/metal composites. Without any organic binder, conductive additive and additional current collector, the hybrid electrodes can be directly used as anodes and show highly reversible specific capacity with high-rate capability and long cyclic stability.

Flagellar filament bio-templated inorganic oxide materials - towards an efficient lithium battery anode

NASA Astrophysics Data System (ADS)

Beznosov, Sergei N.; Veluri, Pavan S.; Pyatibratov, Mikhail G.; Chatterjee, Abhijit; Macfarlane, Douglas R.; Fedorov, Oleg V.; Mitra, Sagar

2015-01-01

Designing a new generation of energy-intensive and sustainable electrode materials for batteries to power a variety of applications is an imperative task. The use of biomaterials as a nanosized structural template for these materials has the potential to produce hitherto unachievable structures. In this report, we have used genetically modified flagellar filaments of the extremely halophilic archaea species Halobacterium salinarum to synthesize nanostructured iron oxide composites for use as a lithium-ion battery anode. The electrode demonstrated a superior electrochemical performance compared to existing literature results, with good capacity retention of 1032 mAh g-1 after 50 cycles and with high rate capability, delivering 770 mAh g-1 at 5 A g-1 (~5 C) discharge rate. This unique flagellar filament based template has the potential to provide access to other highly structured advanced energy materials in the future.

Long Pulse Operation on Tore-Supra: Towards Steady State

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

Moreau, P.; Bucalossi, J.; Brosset, C.

The experimental programme of Tore Supra is devoted to the study of technology and physics issues associated to long-duration high performance discharges. This new domain of operation requires simultaneously and in steady state: heat removal capability, particle exhaust, fully non-inductive current drive, advanced technology integration and real time plasma control. The long discharge allows for addressing new time scale physic such as the wall particle retention and erosion. Moreover, the physics of fully non-inductive discharges is full of novelty, namely: the MHD stability, the slow spontaneous oscillation of the central electron temperature or the outstanding inward particle pinch.

Nationwide Increase in Cryptorchidism After the Fukushima Nuclear Accident.

PubMed

Murase, Kaori; Murase, Joe; Machidori, Koji; Mizuno, Kentaro; Hayashi, Yutaro; Kohri, Kenjiro

2018-05-08

To estimate the change of discharge rate after cryptorchidism surgery between pre- and postdisaster in Japan. Cryptorchidism cannot be diagnosed before birth and is not a factor that would influence a woman's decision to seek an abortion. Therefore, this disease is considered suitable for assessing how the Great East Japan Earthquake and the subsequent Fukushima Daiichi nuclear accident (2011) influenced congenital diseases. We obtained cryptorchidism discharge data collected over 6 years from hospitals that were included in an impact assessment survey of the Diagnosis Procedure Combination survey database in Japan and used these data to estimate the discharge rate after cryptorchidism surgery before and after the disaster. The 94 hospitals in Japan that participated in Diagnosis Procedure Combination system and had 10 or more discharges after cryptorchidism surgery within successive 6 years covering pre- and postdisaster period (FY2010-FY2015) were involved. The change in discharge rate between pre- and postdisaster was analyzed using a Bayesian generalized linear mixed model. Nationwide, a 13.4% (95% credible interval 4.7%-23.0%) increase in discharge rates was estimated. The results of all sensitivity analyses were similar to the reported main results. The discharge rate of cryptorchidism was increased nationwide. The rates of low-weight babies or preterm births, risk factors of cryptorchidism, were almost constant during the study period, and age distribution of the surgery was also not changed, which suggested that the other factors that associated with the disaster increased the incidence of cryptorchidism. Copyright © 2018 Elsevier Inc. All rights reserved.

Predictors and outcome of discharge against medical advice from the psychiatric units of a general hospital.

PubMed

Pages, K P; Russo, J E; Wingerson, D K; Ries, R K; Roy-Byrne, P P; Cowley, D S

1998-09-01

The study examined predictors of discharge against medical advice (AMA) and outcomes of psychiatric patients with AMA discharges, as measured by poorer symptom ratings at discharge and higher rates of rehospitalization. A total of 195 patients discharged AMA from general hospital psychiatric units were compared retrospectively with 2,230 regularly discharged patients. AMA status was defined as signing out against medical advice, being absent without leave, or being administratively discharged. All patients received standardized assessments within 24 hours of admission and at discharge. Demographic characteristics, psychiatric history, DSA-IV psychiatric and substance use diagnoses, and scores on an expanded 32-item version of the Psychiatric Symptom Assessment Scale were compared. The groups did not differ in primary psychiatric diagnoses. Patients discharged AMA were significantly less likely to be Caucasian or to be functionally impaired due to physical illness. They were more likely to live alone, have a substance use diagnosis, use more psychoactive substances, and have more previous hospitalizations. Patients discharged AMA had significantly shorter lengths of stay, higher rehospitalization rates, and more severe symptoms at discharge, even when length of stay was taken into account. The differences between the groups in male gender and young age were better accounted for by a greater likelihood of substance abuse in these groups. The results suggest a profile of patients who may be discharged AMA. Such patients have worse outcomes and are more likely to be high utilizers of inpatient resources. Aggressive identification of patients likely to be discharged AMA and early discharge planning for appropriate outpatient treatment are recommended.

Costs and outcomes associated with alternative discharge strategies following joint replacement surgery: analysis of an observational study using a propensity score.

PubMed

Coyte, P C; Young, W; Croxford, R

2000-11-01

We estimated the impact of alternative discharge strategies, following joint replacement (JR) surgery, on acute care readmission rates and the total cost of a continuum of care. Following surgery, patients were discharged to one of four destinations. Propensity scores were used to adjust costs and outcomes for potential bias in the assignment of discharge destinations. We demonstrated that the use of rehabilitation hospitals may lower readmission rates, but at a prohibitive incremental cost of each saved readmission, that patients discharged with home care had longer acute care stays than other patients, that the provision of home care services increased health system costs, and that acute care readmission rates were greatest among patients discharged with home care. Our study should be seen as one important stepping stone towards a full economic evaluation of the continuum of care for patients.

N2O and CO production by electric discharge - Atmospheric implications. [Venus atmosphere simulation

NASA Technical Reports Server (NTRS)

Levine, J. S.; Howell, W. E.; Hughes, R. E.; Chameides, W. L.

1979-01-01

Enhanced levels of N2O and CO were measured in tropospheric air samples exposed to a 17,500-J laboratory discharge. These enhanced levels correspond to an N2O production rate of about 4 trillion molecules/J and a CO production rate of about 10 to the 14th molecules/J. The CO measurements suggest that the primary region of chemical production in the discharge is the shocked air surrounding the lightning channel, as opposed to the slower-cooling inner core. Additional experiments in a simulated Venus atmosphere (CO2 - 95%, N2 - 5%, at one atmosphere) indicate an enhancement of CO from less than 0.1 ppm prior to the laboratory discharge to more than 2000 ppm after the discharge. Comparison with theoretical calculations appears to confirm the ability of a shock-wave/thermochemical model to predict the rate of production of trace species by an electrical discharge.

Techniques for computing discharge at four Navigation Dams on the Illinois and Des Plaines Rivers in Illinois

USGS Publications Warehouse

Mades, Dean M.; Weiss, Linda S.; Gray, John R.

1991-01-01

Techniques for computing discharge are developed for Brandon Road Dam on the Des Plaines River and for Dresden Island, Marseilles, and Starved Rock Dams on the Illinois River. At Brandon Road Dam, streamflow is regulated by the operation of Tainter gates and headgates. At Dresden Island, Marseilles, and Starved Rock Dams, only Tainter gates are operated to regulate streamflow. The locks at all dams are equipped with culvert valves that are used to fill and empty the lock. The techniques facilitate determination of discharge at locations along the upper Illinois Waterway where no streamflow-gaging stations exist. The techniques are also useful for computing low flows when the water-surface slope between control structures on the river approaches zero and traditional methods of determining discharge based on slope are unsatisfactory. Two techniques can be used to compute discharge at the dams--gate ratings and tailwater ratings . A gate ratingdescribes the relation between discharge, gate opening, tailwater stage, and headwater stage. A tailwater rating describes the relation between tailwater stage and discharge. Gate ratings for Tainter gates at Dresden Island, Marseilles, and Starved Rock Dams are based on a total of 78 measurements of discharge that range from 569 to 86,400 cubic feet per second. Flood hydrographs developed from the gate ratings and Lockmaster records of gate opening and stage compare closely with streamflow records published for nearby streamflow-gaging stations. Additional measurements are needed to verify gate ratings for Tainter gates and headgates at Brandon Road Dam after the dam rehabilitation is completed. Extensive leakage past deteriorated headgates and sluice gates contributed to uncertainty in the ratings developed for this dam. A useful tailwater rating is developed for Marseilles Dam. Tailwater ratings for Dresden Island Dam and Starved Rock Dam are of limited use because of varying downstream channel-storage conditions. A tailwater rating could not be developed for Brandon Road Dam because its tailwater pool is substantially affected by the headwater pool of Dresden Island Dam.

Coupling fine particle and bedload transport in gravel-bedded streams

NASA Astrophysics Data System (ADS)

Park, Jungsu; Hunt, James R.

2017-09-01

Fine particles in the silt- and clay-size range are important determinants of surface water quality. Since fine particle loading rates are not unique functions of stream discharge this limits the utility of the available models for water quality assessment. Data from 38 minimally developed watersheds within the United States Geological Survey stream gauging network in California, USA reveal three lines of evidence that fine particle release is coupled with bedload transport. First, there is a transition in fine particle loading rate as a function of discharge for gravel-bedded sediments that does not appear when the sediment bed is composed of sand, cobbles, boulders, or bedrock. Second, the discharge at the transition in the loading rate is correlated with the initiation of gravel mobilization. Third, high frequency particle concentration and discharge data are dominated by clockwise hysteresis where rising limb discharges generally have higher concentrations than falling limb discharges. These three observations across multiple watersheds lead to a conceptual model that fine particles accumulate within the sediment bed at discharges less than the transition and then the gravel bed fluidizes with fine particle release at discharges above the transition discharge. While these observations were individually recognized in the literature, this analysis provides a consistent conceptual model based on the coupling of fine particle dynamics with filtration at low discharges and gravel bed fluidization at higher discharges.

Heterogeneous neuronal firing patterns during interictal epileptiform discharges in the human cortex

PubMed Central

Keller, Corey J.; Truccolo, Wilson; Gale, John T.; Eskandar, Emad; Thesen, Thomas; Carlson, Chad; Devinsky, Orrin; Kuzniecky, Ruben; Doyle, Werner K.; Madsen, Joseph R.; Schomer, Donald L.; Mehta, Ashesh D.; Brown, Emery N.; Hochberg, Leigh R.; Ulbert, István; Halgren, Eric

2010-01-01

Epileptic cortex is characterized by paroxysmal electrical discharges. Analysis of these interictal discharges typically manifests as spike–wave complexes on electroencephalography, and plays a critical role in diagnosing and treating epilepsy. Despite their fundamental importance, little is known about the neurophysiological mechanisms generating these events in human focal epilepsy. Using three different systems of microelectrodes, we recorded local field potentials and single-unit action potentials during interictal discharges in patients with medically intractable focal epilepsy undergoing diagnostic workup for localization of seizure foci. We studied 336 single units in 20 patients. Ten different cortical areas and the hippocampus, including regions both inside and outside the seizure focus, were sampled. In three of these patients, high density microelectrode arrays simultaneously recorded between 43 and 166 single units from a small (4 mm × 4 mm) patch of cortex. We examined how the firing rates of individual neurons changed during interictal discharges by determining whether the firing rate during the event was the same, above or below a median baseline firing rate estimated from interictal discharge-free periods (Kruskal–Wallis one-way analysis, P<0.05). Only 48% of the recorded units showed such a modulation in firing rate within 500 ms of the discharge. Units modulated during the discharge exhibited significantly higher baseline firing and bursting rates than unmodulated units. As expected, many units (27% of the modulated population) showed an increase in firing rate during the fast segment of the discharge (±35 ms from the peak of the discharge), while 50% showed a decrease during the slow wave. Notably, in direct contrast to predictions based on models of a pure paroxysmal depolarizing shift, 7.7% of modulated units recorded in or near the seizure focus showed a decrease in activity well ahead (0–300 ms) of the discharge onset, while 12.2% of units increased in activity in this period. No such pre-discharge changes were seen in regions well outside the seizure focus. In many recordings there was also a decrease in broadband field potential activity during this same pre-discharge period. The different patterns of interictal discharge-modulated firing were classified into more than 15 different categories. This heterogeneity in single unit activity was present within small cortical regions as well as inside and outside the seizure onset zone, suggesting that interictal epileptiform activity in patients with epilepsy is not a simple paroxysm of hypersynchronous excitatory activity, but rather represents an interplay of multiple distinct neuronal types within complex neuronal networks. PMID:20511283

Multi-dimensional optical and laser-based diagnostics of low-temperature ionized plasma discharges

DOE PAGES

Barnat, Edward V.

2011-09-15

In this paper, a review of work centered on the utilization of multi-dimensional optical diagnostics to study phenomena arising in radiofrequency plasma discharges is given. The diagnostics range from passive techniques such as optical emission to more active techniques utilizing nanosecond lasers capable of both high temporal and spatial resolution. In this review, emphasis is placed on observations that would have been more difficult, if not impossible, to make without the use of such diagnostic techniques. Examples include the sheath structure around an electrode consisting of two different metals, double layers that arise in magnetized hydrogen discharges, or a largemore » region of depleted argon 1s 4 levels around a biased probe in an rf discharge.« less

Nanosecond Plasma Enhanced H2/O2/N2 Premixed Flat Flames

DTIC Science & Technology

2014-01-01

Simulations are conducted with a one-dimensional, multi-scale, pulsed -discharge model with detailed plasma-combustion kinetics to develop additional insight... model framework. The reduced electric field, E/N, during each pulse varies inversely with number density. A significant portion of the input energy is...dimensional numerical model [4, 12] capable of resolving electric field transients over nanosecond timescales (during each discharge pulse ) and radical

Probing RFP Density Limits and the Interaction of Pellet Fueling and NBI Heating on MST

NASA Astrophysics Data System (ADS)

Caspary, K. J.; Chapman, B. E.; Anderson, J. K.; Limbach, S. T.; Oliva, S. P.; Sarff, J. S.; Waksman, J.; Combs, S. K.; Foust, C. R.

2013-10-01

Pellet fueling on MST has previously achieved Greenwald fractions of up to 1.5 in 200 kA improved confinement discharges. Additionally, pellet fueling to densities above the Greenwald limit in 200 kA standard discharges resulted in early termination of the plasma, but pellet size was insufficient to exceed the limit for higher current discharges. To this end, the pellet injector on MST has been upgraded to increase the maximum fueling capability by increasing the size of the pellet guide tubes, which constrain the lateral motion of the pellet in flight, to accommodate pellets of up to 4.0 mm in diameter. These 4.0 mm pellets are capable of triggering density limit terminations for MST's peak current of 600 kA. An unexpected improvement in the pellet speed and mass control was also observed compared to the smaller diameter pellets. Exploring the effect of increased density on NBI particle and heat deposition shows that for MST's 1 MW tangential NBI, core deposition of 25 keV neutrals is optimized for densities of 2-3 × 1019 m-3. This is key for beta limit studies in pellet fueled discharges with improved confinement where maximum NBI heating is desired. An observed toroidal deflection of pellets injected into NBI heated discharges is consistent with asymmetric ablation due to the fast ion population. In 200 kA improved confinement plasmas with NBI heating, pellet fueling has achieved a Greenwald fraction of 2.0. Work supported by US DoE.

Effects of pulse frequency of input power on the physical and chemical properties of pulsed streamer discharge plasmas in water

NASA Astrophysics Data System (ADS)

Ruma; Lukes, P.; Aoki, N.; Spetlikova, E.; Hosseini, S. H. R.; Sakugawa, T.; Akiyama, H.

2013-03-01

A repetitive pulsed-power modulator, which employs a magnetic pulse compression circuit with a high-speed thyristor switch, was used to study the effects of the pulse repetition rate of input power on the physical and chemical properties of pulsed discharges in water. Positive high-voltage pulses of 20 kV with repetition rates of up to 1 kHz were used to generate a discharge in water using the point-to-plane electrode geometry. By varying the pulse repetition rate, two distinct modes of the discharge plasma were formed in water. The first mode was characterized by the formation of a corona-like discharge propagating through water in the form of streamer channels. The second mode was formed typically above 500 Hz, when the formation of streamer channels in water was suppressed and all plasmas occurred inside a spheroidal aggregate of very fine gas bubbles surrounding the tip of the high-voltage electrode. The production of hydrogen peroxide, degradation of organic dye Acid Orange 7 (AO7) and inactivation of bacteria Escherichia coli by the discharge in water were studied under different discharge plasma modes in dependence on the pulse repetition rate of input power. The efficiency of both chemical and biocidal processes induced by the plasma in water decreased significantly with pulse repetition rates above 500 Hz.

Discharge properties of abductor hallucis before, during, and after an isometric fatigue task.

PubMed

Kelly, Luke A; Racinais, Sebastien; Cresswell, Andrew G

2013-08-01

Abductor hallucis is the largest muscle in the arch of the human foot and comprises few motor units relative to its physiological cross-sectional area. It has been described as a postural muscle, aiding in the stabilization of the longitudinal arch during stance and gait. The purpose of this study was to describe the discharge properties of abductor hallucis motor units during ramp and hold isometric contractions, as well as its discharge characteristics during fatigue. Intramuscular electromyographic recordings from abductor hallucis were made in 5 subjects; from those recordings, 42 single motor units were decomposed. Data were recorded during isometric ramp contractions at 60% maximum voluntary contraction (MVC), performed before and after a submaximal isometric contraction to failure (mean force 41.3 ± 15.3% MVC, mean duration 233 ± 116 s). Motor unit recruitment thresholds ranged from 10.3 to 54.2% MVC. No significant difference was observed between recruitment and derecruitment thresholds or their respective discharge rates for both the initial and postfatigue ramp contractions (all P > 0.25). Recruitment threshold was positively correlated with recruitment discharge rate (r = 0.47, P < 0.03). All motor units attained similar peak discharge rates (14.0 ± 0.25 pulses/s) and were not correlated with recruitment threshold. Thirteen motor units could be followed during the isometric fatigue task, with a decline in discharge rate and increase in discharge rate variability occurring in the final 25% of the task (both P < 0.05). We have shown that abductor hallucis motor units discharge relatively slowly and are considerably resistant to fatigue. These characteristics may be effective for generating and sustaining the substantial level of force that is required to stabilize the longitudinal arch during weight bearing.

Tracking the Chemical and Structural Evolution of the TiS2 Electrode in the Lithium-Ion Cell Using Operando X-ray Absorption Spectroscopy.

PubMed

Zhang, Liang; Sun, Dan; Kang, Jun; Wang, Hsiao-Tsu; Hsieh, Shang-Hsien; Pong, Way-Faung; Bechtel, Hans A; Feng, Jun; Wang, Lin-Wang; Cairns, Elton J; Guo, Jinghua

2018-06-06

As the lightest and cheapest transition metal dichalcogenide, TiS 2 possesses great potential as an electrode material for lithium batteries due to the advantages of high energy density storage capability, fast ion diffusion rate, and low volume expansion. Despite the extensive investigation of its electrochemical properties, the fundamental discharge-charge reaction mechanism of the TiS 2 electrode is still elusive. Here, by a combination of ex situ and operando X-ray absorption spectroscopy with density functional theory calculations, we have clearly elucidated the evolution of the structural and chemical properties of TiS 2 during the discharge-charge processes. The lithium intercalation reaction is highly reversible and both Ti and sulfur are involved in the redox reaction during the discharge and charge processes. In contrast, the conversion reaction of TiS 2 is partially reversible in the first cycle. However, Ti-O related compounds are developed during electrochemical cycling over extended cycles, which results in the decrease of the conversion reaction reversibility and the rapid capacity fading. In addition, the solid electrolyte interphase formed on the electrode surface is found to be highly dynamic in the initial cycles and then gradually becomes more stable upon further cycling. Such understanding is important for the future design and optimization of TiS 2 based electrodes for lithium batteries.

Effects of compatibility of polymer binders with solvate ionic liquid electrolytes on discharge and charge reactions of lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Nakazawa, Toshitada; Ikoma, Ai; Kido, Ryosuke; Ueno, Kazuhide; Dokko, Kaoru; Watanabe, Masayoshi

2016-03-01

Electrochemical reactions in Li-S cells with a solvate ionic liquid (SIL) electrolyte composed of tetraglyme (G4) and Li[TFSA] (TFSA: bis(trifluoromethanesulfonyl)amide) are studied. The sulfur cathode (S cathode) comprises sulfur, carbon powder, and a polymer binder. Poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA-x) with different degrees of saponification (x%) are used as binders to prepare the composite cathodes. For the Li-S cell containing PEO binder, lithium polysulfides (Li2Sm, 2 ≤ m ≤ 8), reaction intermediates of the S cathode, dissolve into the electrolyte, and Li2Sm acts as a redox shuttle in the Li-S cell. In contrast, in the Li-S cell with PVA-x binder, the dissolution of Li2Sm is suppressed, leading to high columbic efficiencies during charge-discharge cycles. The compatibility of the PVA-x binder with the SIL electrolyte changes depending on the degree of saponification. Decreasing the degree of saponification leads to increased electrolyte uptake by the PVA-x binder, increasing the charge and discharge capacities of Li-S cell. The rate capability of Li-S cell is also enhanced by the partial swelling of the PVA-x binder. The enhanced performance of Li-S cell containing PVA-x is attributed to the lowering of resistance of Li+ ion transport in the composite cathode.

Dynamic study of sub-micro sized LiFePO4 cathodes by in-situ tender X-ray absorption near edge structure

NASA Astrophysics Data System (ADS)

Wang, Dongniu; Wang, Huixin; Yang, Jinli; Zhou, Jigang; Hu, Yongfeng; Xiao, Qunfeng; Fang, Haitao; Sham, Tsun-Kong

2016-01-01

Olivine-type phosphates (LiMPO4, M = Fe, Mn, Co) are promising cathode materials for lithium-ion batteries that are generally accepted to follow first order equilibrium phase transformations. Herein, the phase transformation dynamics of sub-micro sized LiFePO4 particles with limited rate capability at a low current density of 0.14 C was investigated. An in-situ X-ray Absorption Near Edge Structure (XANES) measurement was conducted at the Fe and P K-edge for the dynamic studies upon lithiation and delithiation. Fe K-edge XANES spectra demonstrate that not only lithium-rich intermediate phase LixFePO4 (x = 0.6-0.75), but also lithium-poor intermediate phase LiyFePO4 (y = 0.1-0.25) exist during the charge and discharge, respectively. Furthermore, during charge and discharge, a fluctuation of the FePO4 and LiFePO4 fractions obtained by liner combination fitting around the imaginary phase fractions followed Faraday's law and the equilibrium first-order two-phase transformation versus reaction time is present, respectively. The charging and discharging process has a reversible phase transformation dynamics with symmetric structural evolution routes. P K-edge XANES spectra reveal an enrichment of PF6-1 anions at the surface of the electrode during charging.

Lithium rich cathode/graphite anode combination for lithium ion cells with high tolerance to near zero volt storage

NASA Astrophysics Data System (ADS)

Crompton, K. R.; Staub, J. W.; Hladky, M. P.; Landi, B. J.

2017-03-01

Management of reversible lithium is an advantageous approach to design lithium ion cells that are tolerant to near zero volt (NZV) storage under fixed resistive load towards highly controllable, enhanced user-inactive safety. Presently, the first cycle loss from a high energy density Li-rich HE5050 cathode is used to provide excess reversible lithium when paired with an appropriately capacity matched mesocarbon microbead (MCMB) anode. Cells utilizing 1.2 M LiPF6 3:7 v/v ethylene carbonate:ethyl methyl carbonate electrolyte and a lithium reference were used for 3-electrode testing. After conditioning, a fixed resistive load was applied to 3-electrode cells for 72 or 168-h during which the anode potential and electrode asymptotic potential (EAP) remained less than the copper dissolution potential. After multiple storage cycles (room temperature or 40 °C), the NZV coulombic efficiency (cell reversibility) exceeded 97% and the discharge capacity retention was >98%. Conventional 2-electrode HE5050/MCMB pouch cells stored at NZV or open circuit for 3 days had nearly identical rate capability (up to 5C) and discharge performance stability (for 500 cycles under a 30% depth of discharge low-earth-orbit regime). Thus, lithium ion cells with appropriately capacity matched HE5050/MCMB electrodes have excellent tolerance to prolonged NZV storage, which can lead to enhanced user-inactive safety.

Dual-protection of a graphene-sulfur composite by a compact graphene skin and an atomic layer deposited oxide coating for a lithium-sulfur battery.

PubMed

Yu, Mingpeng; Wang, Aiji; Tian, Fuyang; Song, Hongquan; Wang, Yinshu; Li, Chun; Hong, Jong-Dal; Shi, Gaoquan

2015-03-12

A reduced graphene oxide (rGO)-sulfur composite aerogel with a compact self-assembled rGO skin was further modified by an atomic layer deposition (ALD) of ZnO or MgO layer, and used as a free-standing electrode material of a lithium-sulfur (Li-S) battery. The rGO skin and ALD-oxide coating worked as natural and artificial barriers to constrain the polysulfides within the cathode region. As a result, the Li-S battery based on this electrode material exhibited superior cycling stability, good rate capability and high coulombic efficiency. Furthermore, ALD-ZnO coating was tested for performance improvement and found to be more effective than ALD-MgO coating. The ZnO modified G-S electrode with 55 wt% sulfur loading delivered a maximum discharge capacity of 998 mA h g(-1) at a current density of 0.2 C. A high capacity of 846 mA h g(-1) was achieved after charging/discharging for 100 cycles with a coulombic efficiency of over 92%. In the case of using LiNO3 as a shuttle inhibitor, this electrode showed an initial discharge capacity of 796 mA h g(-1) and a capacity retention of 81% after 250 cycles at a current density of 1 C with an average coulombic efficiency higher than 99.7%.

ALD of Al2O3 for Highly Improved Performance in Li-Ion Batteries

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

Dillon, A.; Jung, Y. S.; Ban, C.

2012-01-01

Significant advances in energy density, rate capability and safety will be required for the implementation of Li-ion batteries in next generation electric vehicles. We have demonstrated atomic layer deposition (ALD) as a promising method to enable superior cycling performance for a vast variety of battery electrodes. The electrodes range from already demonstrated commercial technologies (cycled under extreme conditions) to new materials that could eventually lead to batteries with higher energy densities. For example, an Al2O3 ALD coating with a thickness of ~ 8 A was able to stabilize the cycling of unexplored MoO3 nanoparticle anodes with a high volume expansion.more » The ALD coating enabled stable cycling at C/2 with a capacity of ~ 900 mAh/g. Furthermore, rate capability studies showed the ALD-coated electrode maintained a capacity of 600 mAh/g at 5C. For uncoated electrodes it was only possible to observe stable cycling at C/10. Also, we recently reported that a thin ALD Al2O3 coating with a thickness of ~5 A can enable natural graphite (NG) electrodes to exhibit remarkably durable cycling at 50 degrees C. The ALD-coated NG electrodes displayed a 98% capacity retention after 200 charge-discharge cycles. In contrast, bare NG showed a rapid decay. Additionally, Al2O3 ALD films with a thickness of 2 to 4 A have been shown to allow LiCoO2 to exhibit 89% capacity retention after 120 charge-discharge cycles performed up to 4.5 V vs Li/Li+. Bare LiCoO2 rapidly deteriorated in the first few cycles. The capacity fade is likely caused by oxidative decomposition of the electrolyte at higher potentials or perhaps cobalt dissolution. Interestingly, we have recently fabricated full cells of NG and LiCoO2 where we coated both electrodes, one or the other electrode as well as neither electrode. In creating these full cells, we observed some surprising results that lead us to obtain a greater understanding of the ALD coatings. We have also recently coated a binder free LiNi0.04Mn0.04Co02O2 electrode containing 5 wt% single-walled carbon nanotubes as the conductive additive and demonstrated both high rate capability as well as the ability to cycle the cathode to 5 V vrs. Li/Li+. Finally, we coated a Celgard (TM) separator and enabled stable cycling in a high dielectric electrolyte. These results will be presented in detail.« less

Structural and Electrochemical Characteristics of Ca-Doped “Flower-like” Li 4Ti 5O 12 Motifs as High-Rate Anode Materials for Lithium-Ion Batteries

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

Wang, Lei; Zhang, Yiman; Guo, Haoyue

Doped motifs offer an intriguing structural pathway toward improving conductivity for battery applications. Specifically, Ca-doped, three-dimensional “flower-like” Li 4–xCa xTi 5O 12 (“x” = 0, 0.1, 0.15, and 0.2) micrometer-scale spheres have been successfully prepared for the first time using a simple and reproducible hydrothermal reaction followed by a short calcination process. The products were experimentally characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge testing. Calcium dopantmore » ions were shown to be uniformly distributed within the LTO structure without altering the underlying “flower-like” morphology. The largest lattice expansion and the highest Ti 3+ ratios were noted with XRD and XPS, respectively, whereas increased charge transfer conductivity and decreased Li +-ion diffusion coefficients were displayed in EIS for the Li 4–xCa xTi 5O 12 (“x” = 0.2) sample. The “x” = 0.2 sample yielded a higher rate capability, an excellent reversibility, and a superior cycling stability, delivering 151 and 143 mAh/g under discharge rates of 20C and 40C at cycles 60 and 70, respectively. In addition, a high cycling stability was demonstrated with a capacity retention of 92% after 300 cycles at a very high discharge rate of 20C. In addition, first-principles calculations based on density functional theory (DFT) were conducted with the goal of further elucidating and understanding the nature of the doping mechanism in this study. The DFT calculations not only determined the structure of the Ca-doped Li 4Ti 5O 12, which was found to be in accordance with the experimentally measured XPD pattern, but also yielded valuable insights into the doping-induced effect on both the atomic and electronic structures of Li 4Ti 5O 12.« less

Structural and Electrochemical Characteristics of Ca-Doped “Flower-like” Li 4Ti 5O 12 Motifs as High-Rate Anode Materials for Lithium-Ion Batteries

DOE PAGES

Wang, Lei; Zhang, Yiman; Guo, Haoyue; ...

2018-01-22

Doped motifs offer an intriguing structural pathway toward improving conductivity for battery applications. Specifically, Ca-doped, three-dimensional “flower-like” Li 4–xCa xTi 5O 12 (“x” = 0, 0.1, 0.15, and 0.2) micrometer-scale spheres have been successfully prepared for the first time using a simple and reproducible hydrothermal reaction followed by a short calcination process. The products were experimentally characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge testing. Calcium dopantmore » ions were shown to be uniformly distributed within the LTO structure without altering the underlying “flower-like” morphology. The largest lattice expansion and the highest Ti 3+ ratios were noted with XRD and XPS, respectively, whereas increased charge transfer conductivity and decreased Li +-ion diffusion coefficients were displayed in EIS for the Li 4–xCa xTi 5O 12 (“x” = 0.2) sample. The “x” = 0.2 sample yielded a higher rate capability, an excellent reversibility, and a superior cycling stability, delivering 151 and 143 mAh/g under discharge rates of 20C and 40C at cycles 60 and 70, respectively. In addition, a high cycling stability was demonstrated with a capacity retention of 92% after 300 cycles at a very high discharge rate of 20C. In addition, first-principles calculations based on density functional theory (DFT) were conducted with the goal of further elucidating and understanding the nature of the doping mechanism in this study. The DFT calculations not only determined the structure of the Ca-doped Li 4Ti 5O 12, which was found to be in accordance with the experimentally measured XPD pattern, but also yielded valuable insights into the doping-induced effect on both the atomic and electronic structures of Li 4Ti 5O 12.« less

Synthesis of three-dimensionally interconnected sulfur-rich polymers for cathode materials of high-rate lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Kim, Hoon; Lee, Joungphil; Ahn, Hyungmin; Kim, Onnuri; Park, Moon Jeong

2015-06-01

Elemental sulfur is one of the most attractive cathode active materials in lithium batteries because of its high theoretical specific capacity. Despite the positive aspect, lithium-sulfur batteries have suffered from severe capacity fading and limited rate capability. Here we report facile large-scale synthesis of a class of organosulfur compounds that could open a new chapter in designing cathode materials to advance lithium-sulfur battery technologies. Porous trithiocyanuric acid crystals are synthesized for use as a soft template, where the ring-opening polymerization of elemental sulfur takes place along the thiol surfaces to create three-dimensionally interconnected sulfur-rich phases. Our lithium-sulfur cells display discharge capacity of 945 mAh g-1 after 100 cycles at 0.2 C with high-capacity retention of 92%, as well as lifetimes of 450 cycles. Particularly, the organized amine groups in the crystals increase Li+-ion transfer rate, affording a rate performance of 1210, mAh g-1 at 0.1 C and 730 mAh g-1 at 5 C.

Synthesis of three-dimensionally interconnected sulfur-rich polymers for cathode materials of high-rate lithium–sulfur batteries

PubMed Central

Kim, Hoon; Lee, Joungphil; Ahn, Hyungmin; Kim, Onnuri; Park, Moon Jeong

2015-01-01

Elemental sulfur is one of the most attractive cathode active materials in lithium batteries because of its high theoretical specific capacity. Despite the positive aspect, lithium–sulfur batteries have suffered from severe capacity fading and limited rate capability. Here we report facile large-scale synthesis of a class of organosulfur compounds that could open a new chapter in designing cathode materials to advance lithium–sulfur battery technologies. Porous trithiocyanuric acid crystals are synthesized for use as a soft template, where the ring-opening polymerization of elemental sulfur takes place along the thiol surfaces to create three-dimensionally interconnected sulfur-rich phases. Our lithium–sulfur cells display discharge capacity of 945 mAh g−1 after 100 cycles at 0.2 C with high-capacity retention of 92%, as well as lifetimes of 450 cycles. Particularly, the organized amine groups in the crystals increase Li+-ion transfer rate, affording a rate performance of 1210, mAh g−1 at 0.1 C and 730 mAh g−1 at 5 C. PMID:26065407

The simultaneous discharge of liquid and grains from a silo

NASA Astrophysics Data System (ADS)

Cervantes-Álvarez, A. M.; Hidalgo-Caballero, S.; Pacheco-Vázquez, F.

2018-04-01

The flow rate of water through an orifice at the bottom of a container depends on the hydrostatic pressure whereas for a dry granular material it is nearly constant. But what happens during the simultaneous discharge of grains and liquid from a silo? By measuring the flow rate as a function of time, we found that (i) different regimes appear, going from the constant flow rate to a hydrostatic-like discharge depending on the aperture size and grain diameter, (ii) the mixed material is always discharged faster than dry grains but slower than liquid, (iii) for the mixture, the liquid level drops faster than the grain level, but they are always linearly proportional to one another, and (iv) a sudden growth in the flow rate happens during the transition from a biphasic discharge to a single phase discharge. These results are associated to the competition between the decrease in hydrostatic pressure above the granular bed and the hydrodynamic resistance. A model combining Darcy's law with Bernoulli and mass conservation equations is proposed, and the numerical results are in good agreement with experiments.

Remotely Characterizing the Topographic and Thermal Evolution of Kīlauea's Lava Flow Field

NASA Astrophysics Data System (ADS)

Rumpf, M. E.; Vaughan, R. G.; Poland, M. P.

2017-12-01

New technologies in satellite data acquisition and the continuous development of analysis software capabilities are greatly improving the ability of scientists to monitor volcanoes in near-real-time. Satellite-based thermal infrared (TIR) data are used to monitor and analyze new and ongoing volcanic activity by identifying and quantifying surface thermal characteristics and lava flow discharge rates. Improved detector sensitivities provide unprecedented spatial detail in visible to shortwave infrared (VSWIR) satellite imagery. The acquisition of stereo and tri-stereo visible imagery, as well as SAR, by an increasing number of satellite systems enables the creation of digital elevation models (DEMs) at higher temporal frequencies and resolutions than in the past. Free, user-friendly software programs, such as NASA's Ames Stereo Pipeline and Google Earth Engine, ease the accessibility and usability of satellite data to users unfamiliar with traditional analysis techniques. An effective and efficient integration of these technologies can be utilized towards volcano monitoring.Here, we use the active lava flows from the East Rift Zone vents of Kīlauea Volcano, Hawai`i as a testing ground for developing new techniques in multi-sensor volcano remote sensing. We use DEMs generated from stereo and tri-stereo images captured by the WorldView3 and Pleiades satellite systems to assess topographic changes over time at the active flow fields. Time-series data of lava flow area, thickness, and discharge rate developed from thermal emission measurements collected by ASTER, Landsat 8, and WorldView3 are compared to satellite-detected topographic changes and to ground observations of flow development to identify behavioral patterns and to monitor flow field evolution. We explore methods of combining these visual and TIR data sets collected by multiple satellite systems with a variety of resolutions and repeat times. Our ultimate goal is to develop integrative tools for near-real-time volcano monitoring. In addition, we recommend improvements to future satellite mission capabilities (e.g., repeat times, resolutions) to improve lava flow monitoring techniques.

River rating complexity

USGS Publications Warehouse

Holmes, Robert R.

2016-01-01

Accuracy of streamflow data depends on the veracity of the rating model used to derive a continuous time series of discharge from the surrogate variables that can readily be collected autonomously at a streamgage. Ratings are typically represented as a simple monotonic increasing function (simple rating), meaning the discharge is a function of stage alone, however this is never truly the case unless the flow is completely uniform at all stages and in transitions from one stage to the next. For example, at some streamflow-monitoring sites the discharge on the rising limb of the hydrograph is discernably larger than the discharge at the same stage on the falling limb of the hydrograph. This is the so-called “loop rating curve” (loop rating). In many cases, these loops are quite small and variation between rising- and falling-limb discharge measurements made at the same stage are well within the accuracy of the measurements. However, certain hydraulic conditions can produce a loop that is large enough to preclude use of a monotonic rating. A detailed data campaign for the Mississippi River at St. Louis, Missouri during a multi-peaked flood over a 56-day period in 2015 demonstrates the rating complexity at this location. The shifting-control method used to deal with complexity at this site matched all measurements within 8%.

Cost-effectiveness of 'Program We Care' for patients with chronic obstructive pulmonary disease: A case-control study.

PubMed

Wong, Eliza Mi Ling; Lo, Shuk Man; Ng, Ying Chu; Lee, Larry Lap Yip; Yuen, T M Y; Chan, Jimmy Tak Shing; Chair, Sek Ying

2016-07-01

To evaluate the effectiveness of a discharge program for patients with chronic obstructive pulmonary disease (COPD) patients on discharge from an emergency medical ward on discharge home rate, hospital length of stay (LOS), inpatient admission rate and cost. Frequent visits to the emergency department (ED) and subsequent hospital admission are common among patients with COPD, which adds a burden to ED and hospital care. A discharge program was implemented in an ED emergency medical ward. The program consisted of multidisciplinary care, discharge planning, discharge health education on disease management, and continued support from the community nursing services. A retrospective case-control study was used. Data were retrieved and compared between 478 COPD program cases and 478 COPD non-program cases. No significant difference was found in age, gender, and triage category, LOS in ED, and readmission rate between the program and non-program groups. The program group demonstrated a significantly higher discharge home rate from the ED (33.89% vs. 20.08%) and fewer medical admissions (40.59% vs. 55.02%) compared with the non-program group, resulting in lower total medical costs after the program was implemented. The program provides insight on the strategic planning for discharge care in a short stay unit of emergency department. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Implementation of a post-discharge surgical site infection system in herniorrhaphy and mastectomy procedures].

PubMed

San Juan Sanz, Isabel; Díaz-Agero-Pérez, Cristina; Robustillo-Rodela, Ana; Pita López, María José; Oliva Iñiguez, Lourdes; Monge-Jodrá, Vicente

2014-10-01

Monitoring surgical site infection (SSI) performed during hospitalization can underestimate its rates due to the shortening in hospital stay. The aim of this study was to determine the actual rates of SSI using a post-discharge monitoring system. All patients who underwent herniorraphy or mastectomy in the Hospital Universitario Ramón y Cajal from 1 January 2011 to 31 December 2011 were included. SSI data were collected prospectively according to the continuous quality improvement indicators (Indicadores Clinicos de Mejora Continua de la Calidad [INCLIMECC]) monitoring system. Post-discharge follow-up was conducted by telephone survey. A total of 409patients were included in the study, of whom 299 underwent a herniorraphy procedure, and 110 underwent a mastectomy procedure. For herniorrhaphy, the SSI rate increased from 6.02% to 7.6% (the post-discharge survey detected 21.7% of SSI). For mastectomy, the SSI rate increased from 1.8% to 3.6% (the post-discharge survey detected 50% of SSI). Post-discharge monitoring showed an increased detection of SSI incidence. Post-discharge monitoring is useful to analyze the real trend of SSI, and evaluate improvement actions. Post-discharge follow-up methods need to standardised. Copyright © 2013 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Flexible in-plane microsupercapacitors with electrospun NiFe2O4 nanofibers for portable sensing applications.

PubMed

Li, La; Lou, Zheng; Han, Wei; Shen, Guozhen

2016-08-11

The development of wearable electronic devices in recent decades has brought new opportunities in the exploration of micro-supercapacitors as energy storage units. In this work, we report the fabrication of flexible NiFe2O4 nanofiber based in-plane micro-supercapacitors (MSCs), which can serve as energy storage receptors to drive a portable graphene pressure sensor. The obtained NiFe2O4 nanofiber electrodes exhibited a specific capacitance of 2.23 F cm(-3) at the scan rate of 100 mV s(-1), and excellent rate capability and robust cycling stability with a capacitance retention of 93.6% after 10 000 charge/discharge cycles. Moreover, the in-plane MSCs have superior flexibility and outstanding stability even after repetition of charge/discharge cycles during the convex and concave bending states. The MSCs offered a high energy density of 0.197 mWh cm(-3) and power density up to 2.07 W cm(-3). We also coupled the MSCs with a graphene pressure sensor as a micro-integrated system to implement it's pressure response function and used MATLAB to simulate this system behavior as well. The performance of the designed systems exhibited a stable pressure response, and the simulated results coincide well with the experimental data, demonstrating its feasibility in wearable electronic devices.

SnO2/Reduced Graphene Oxide Interlayer Mitigating the Shuttle Effect of Li-S Batteries.

PubMed

Hu, Nana; Lv, Xingshuai; Dai, Ying; Fan, Linlin; Xiong, Dongbin; Li, Xifei

2018-06-06

The short cycle life of lithium-sulfur batteries (LSBs) plagues its practical application. In this study, a uniform SnO 2 /reduced graphene oxide (denoted as SnO 2 /rGO) composite is successfully designed onto the commercial polypropylene separator for use of interlayer of LSBs to decrease the charge-transfer resistance and trap the soluble lithium polysulfides (LPSs). As a result, the assembled devices using the separator modified with the functional interlayer (SnO 2 /rGO) exhibit improved cycle performance; for instance, over 200 cycles at 1C, the discharge capacity of the cells reaches 734 mAh g -1 . The cells also display high rate capability, with the average discharge capacity of 541.9 mAh g -1 at 5C. Additionally, the mechanism of anchoring behavior of the SnO 2 /rGO interlayer was systematically investigated using density functional theory calculations. The results demonstrate that the improved performance is related to the ability of SnO 2 /rGO to effectively absorb S 8 cluster and LPS. The strong Li-O/Sn-S/O-S bonds and tight chemical adsorption between LPS and SnO 2 mitigate the shuttle effect of LSBs. This study demonstrates that engineering the functional interlayer of metal oxide and carbon materials in LSBs may be an easy way to improve their rate capacity and cycling life.

Mg doped Li2FeSiO4/C nanocomposites synthesized by the solvothermal method for lithium ion batteries.

PubMed

Kumar, Ajay; Jayakumar, O D; Jagannath; Bashiri, Parisa; Nazri, G A; Naik, Vaman M; Naik, Ratna

2017-10-14

A series of porous Li 2 Fe 1-x Mg x SiO 4 /C (x = 0, 0.01, 0.02, 0.04) nanocomposites (LFS/C, 1Mg-LFS/C, 2Mg-LFS and 4Mg-LFS/C) have been synthesized via a solvo-thermal method using the Pluronic P123 polymer as an in situ carbon source. Rietveld refinement of the X-ray diffraction data of Li 2 Fe 1-x Mg x SiO 4 /C composites confirms the formation of the monoclinic P2 1 structure of Li 2 FeSiO 4 . The addition of Mg facilitates the growth of impurity-free Li 2 FeSiO 4 with increased crystallinity and particle size. Despite having the same percentage of carbon content (∼15 wt%) in all the samples, the 1Mg-LFS/C nanocomposite delivered the highest initial discharge capacity of 278 mA h g -1 (∼84% of the theoretical capacity) at the C/30 rate and also exhibited the best rate capability and cycle stability (94% retention after 100 charge-discharge cycles at 1C). This is attributed to its large surface area with a narrow pore size distribution and a lower charge transfer resistance with enhanced Li-ion diffusion coefficient compared to other nanocomposites.

Self-discharge mechanism of sealed-type nickel/metal-hydride battery

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

Ikoma, Munehisa; Hoshina, Yasuko; Matsumoto, Isao

1996-06-01

Factors affecting the self-discharge rate of a nickel/metal-hydride (Ni-MH) battery, generally much higher than that of nickel/cadmium (Ni-Cd) battery, are investigated, and the self-discharge mechanism is discussed. Ammonia and amine participate in the shuttle reaction like nitrate ion in the Ni-Cd battery, resulting in acceleration of the self-discharge. When nonwoven fabric made of sulfonated-polypropylene is used as a separator instead of conventional polyamide separator, the self-discharge rate of the Ni-MH battery is strongly depressed, to the same level as that of Ni-Cd battery.

33 CFR 51.8 - Relevant considerations.

Code of Federal Regulations, 2010 CFR

2010-07-01

...; qualification for reenlistment; capability to adjust to military service; and family or personal problems. (c... received; promotions and demotions; prior military service and type of discharge; records of unauthorized...

Facility and market factors affecting transitions from nursing home to community.

PubMed

Arling, Greg; Abrahamson, Kathleen A; Cooke, Valerie; Kane, Robert L; Lewis, Teresa

2011-09-01

Research into nursing home transitions has given limited attention to the facility or community contexts. To identify facility and market factors affecting transitions of nursing home residents back to the community. Multilevel models were used to estimate effects of facility and market factors on facility-level community discharge rates after controlling for resident demographic, health, and functional conditions. Facility discharge rates were adjusted using Empirical Bayes estimation. Annual cohort of first-time admissions (N=24,648) to 378 Minnesota nursing facilities in 75 nursing home markets from July 2005 to June 2006. Community discharge within 90 days of admission; facility occupancy, payer mix, ownership, case-mix acuity, size, admissions from hospitals, nurse staffing level, and proportion of admissions preferring or having support to return to the community; and nursing market population size, average occupancy, market concentration, and availability of home and community-based services. Rates of community discharge (Empirical Bayes residual) were highest in facilities with more residents preferring community discharge, more Medicare days, higher nurse staffing levels, and higher occupancy. In addition, facilities had higher community discharge rates if they were located in markets with a greater ratio of home and community-based services recipients to nursing home residents and with larger populations. State Medicaid programs should undertake system-level interventions that encourage nursing facilities to reduce unused bed capacity, balance the mix of payers, invest in nurse staffing, and take other steps to promote community discharges. In addition, states should increase home and community-based services, particularly in markets with low community discharge rates.

The inter-ELM tungsten erosion profile in DIII-D H-mode discharges and benchmarking with ERO+OEDGE modeling

NASA Astrophysics Data System (ADS)

Abrams, T.; Ding, R.; Guo, H. Y.; Thomas, D. M.; Chrobak, C. P.; Rudakov, D. L.; McLean, A. G.; Unterberg, E. A.; Briesemeister, A. R.; Stangeby, P. C.; Elder, J. D.; Wampler, W. R.; Watkins, J. G.

2017-05-01

It is important to develop a predictive capability for the tungsten source rate near the strike points during H-mode operation in ITER and beyond. H-mode deuterium plasma exposures were performed on W-coated graphite and molybdenum substrates in the DIII-D divertor using DiMES. The W-I 400.9 nm spectral line was monitored by fast filtered diagnostics cross calibrated via a high-resolution spectrometer to resolve inter-ELM W erosion. The effective ionization/photon (S/XB) was calibrated using a unique method developed on DIII-D based on surface analysis. Inferred S/XB values agree with an existing empirical scaling at low electron density (n e) but diverge at higher densities, consistent with recent ADAS atomic physics modeling results. Edge modeling of the inter-ELM phase is conducted via OEDGE utilizing the new capability for charge-state resolved carbon impurity fluxes. ERO modeling is performed with the calculated main ion and impurity plasma background from OEDGE. ERO results demonstrate the importance a mixed-material surface model in the interpretation of W sourcing measurements. It is demonstrated that measured inter-ELM W erosion rates can be well explained by C→W sputtering only if a realistic mixed material model is incorporated.

Multi-channel and porous SiO@N-doped C rods as anodes for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Huang, Xiao; Li, Mingqi

2018-05-01

To improve the cycling stability and rate capability of SiO electrodes, multi-channel and porous SiO@N-doped C (mp-SiO@N-doped C) rods are fabricated by the combination of electrospinning and heat treatment with the assistance of poly(methyl methacrylate) (PMMA). During annealing, in-situ PMMA degradation and gasification lead to the formation of multi-channel structure and more pores. As anodes for lithium ion batteries, the mp-SiO@N-doped C rods exhibit excellent cycling stability. At a current density of 400 mA g-1, a discharge capacity of 806 mAh g-1 can be kept after 250 cycles, the retention of which is over than 100% versus the initial reversible capacity. Compared with the SiO@N-doped C rods synthesized without the help of PMMA, the mp-SiO@N-doped C rods exhibit more excellent rate capability. The excellent electrochemical performance is attributed to the special structure of the mp-SiO@N-doped C rods. In addition to the conductivity improved by carbon fibers, the multi-channel and porous structures not only make ions/electrons transfer and electrolyte diffusion easier, but also contribute to the structural stability of the electrodes.

The compact neutron spectrometer at ASDEX Upgrade.

PubMed

Giacomelli, L; Zimbal, A; Tittelmeier, K; Schuhmacher, H; Tardini, G; Neu, R

2011-12-01

The first neutron spectrometer of ASDEX Upgrade (AUG) was installed in November 2008. It is a compact neutron spectrometer (CNS) based on a BC501A liquid scintillating detector, which can simultaneously measure 2.45-MeV and 14-MeV neutrons emitted from deuterium (D) plasmas and γ radiation. The scintillating detector is coupled to a digital pulse shape discrimination data acquisition (DPSD) system capable of count rates up to 10(6) s(-1). The DPSD system can operate in acquisition and processing mode. With the latter n-γ discrimination is performed off-line based on the two-gate method. The paper describes the tests of the CNS and its installation at AUG. The neutron emission from the D plasma measured during a discharge with high auxiliary heating power was used to validate the CNS performance. The study of the optimal settings for the DPSD data processing to maximize the n-γ discrimination capability of the CNS is reported. The CNS measured both 2.45-MeV and 14-MeV neutrons emitted in AUG D plasmas with a maximum count rate of 5.4 × 10(5) s(-1) (>10 times higher than similar spectrometers previously achieved) with an efficiency of 9.3 × 10(-10) events per AUG neutron.

Effect of Misalignment between Hospital and Provincial Formularies on Medication Discrepancies at Discharge: PPITS (Proton Pump Inhibitor Therapeutic Substitution) Study

PubMed Central

Chua, Doson; Chu, Eric; Lo, Angela; Lo, Melissa; Pataky, Fruzina; Tang, Linda; Bains, Ajay

2012-01-01

Background Medication discrepancies may occur on admission, transfer, or discharge from hospital. Therapeutic interchange within a drug class is a common practice in hospitals, and orders for specific proton pump inhibitors (PPIs) are often substituted with the hospital’s formulary PPI through therapeutic interchange protocols. Rabeprazole is the PPI on the formulary of the British Columbia PharmaCare program. However, different PPIs may appear on the formularies of the province’s hospitals. This misalignment and use of therapeutic interchange may lead to increased rates of medication discrepancies at the time of discharge. Objective To evaluate the effect of formulary misalignment for PPIs between St Paul’s Hospital in Vancouver and the British Columbia PharmaCare program and use of therapeutic interchange on the occurrence of medication discrepancies at discharge. Methods A cohort chart review was performed to compare discharge discrepancy rates for PPI orders between 2 periods: June 2006 to June 2008, when the same PPI appeared on the hospital and provincial formularies, and July 2008 to July 2010, when the designated PPIs differed between the hospital and provincial formularies. Data for the first study period were used to establish the baseline discharge discrepancy rate, and data for the later period represented the discharge discrepancy rate in the presence of misalignment between the hospital and PharmaCare formularies. Results The discharge discrepancy rate for PPIs was 27.3% (24/88) when the 2 formularies were aligned and 49.1% (81/165) when the formularies were misaligned. This represents an absolute increase of 21.8 percentage points in the risk of discharge discrepancies (95% confidence interval 9.8–33.9 percentage points; p < 0.001) when the hospital and provincial formularies were misaligned and the hospital’s therapeutic interchange protocol was used. Conclusions Misalignment between the PPIs specified in the hospital and provincial formularies, combined with use of therapeutic interchange, was associated with a significant increase in medication discrepancies at discharge. PMID:22529401

Utility of functional status for classifying community versus institutional discharges after inpatient rehabilitation for stroke.

PubMed

Reistetter, Timothy A; Graham, James E; Deutsch, Anne; Granger, Carl V; Markello, Samuel; Ottenbacher, Kenneth J

2010-03-01

To evaluate the ability of patient functional status to differentiate between community and institutional discharges after rehabilitation for stroke. Retrospective cross-sectional design. Inpatient rehabilitation facilities contributing to the Uniform Data System for Medical Rehabilitation. Patients (N=157,066) receiving inpatient rehabilitation for stroke from 2006 and 2007. Not applicable. Discharge FIM rating and discharge setting (community vs institutional). Approximately 71% of the sample was discharged to the community. Receiver operating characteristic curve analyses revealed that FIM total performed as well as or better than FIM motor and FIM cognition subscales in differentiating discharge settings. Area under the curve for FIM total was .85, indicating very good ability to identify persons discharged to the community. A FIM total rating of 78 was identified as the optimal cut point for distinguishing between positive (community) and negative (institution) tests. This cut point yielded balanced sensitivity and specificity (both=.77). Discharge planning is complex, involving many factors. Identifying a functional threshold for classifying discharge settings can provide important information to assist in this process. Additional research is needed to determine if the risks and benefits of classification errors justify shifting the cut point to weight either sensitivity or specificity of FIM ratings. Copyright 2010 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Singlet delta oxygen production in a 2D micro-discharge array in air: effect of gas residence time and discharge power

NASA Astrophysics Data System (ADS)

Nayak, Gaurav; Santos Sousa, João; Bruggeman, Peter J.

2017-03-01

The production of singlet delta oxygen (O2(a 1Δg)) is of growing interest for many applications. We report on the measurement of O2(a 1Δg) and ozone (O3) in a room temperature atmospheric pressure discharge in dry air. The plasma source is a 2D array of micro-discharges generated by an alternating current voltage at 20 kHz. The study focuses on the effect of gas flow through the discharge. The maximum investigated flow rate allows reducing the gas residence time in the discharge zone to half the discharge period. Results indicate that the residence time and discharge power have a major effect on the O2(a 1Δg) production. Different O2(a 1Δg) density dependencies on power are observed for different flow rates. Effects of collisional quenching on the as-produced and measured O2(a 1Δg) densities are discussed. The flow rate also allows for control of the O2(a 1Δg) to O3 density ratio in the effluent from 0.7 to conditions of pure O3.

Discharge measurements using a broad-band acoustic Doppler current profiler

USGS Publications Warehouse

Simpson, Michael R.

2002-01-01

The measurement of unsteady or tidally affected flow has been a problem faced by hydrologists for many years. Dynamic discharge conditions impose an unreasonably short time constraint on conventional current-meter discharge-measurement methods, which typically last a minimum of 1 hour. Tidally affected discharge can change more than 100 percent during a 10-minute period. Over the years, the U.S. Geological Survey (USGS) has developed moving-boat discharge-measurement techniques that are much faster but less accurate than conventional methods. For a bibliography of conventional moving-boat publications, see Simpson and Oltmann (1993, page 17). The advent of the acoustic Doppler current profiler (ADCP) made possible the development of a discharge-measurement system capable of more accurately measuring unsteady or tidally affected flow. In most cases, an ADCP discharge-measurement system is dramatically faster than conventional discharge-measurement systems, and has comparable or better accuracy. In many cases, an ADCP discharge-measurement system is the only choice for use at a particular measurement site. ADCP systems are not yet ?turnkey;? they are still under development, and for proper operation, require a significant amount of operator training. Not only must the operator have a rudimentary knowledge of acoustic physics, but also a working knowledge of ADCP operation, the manufacturer's discharge-measurement software, and boating techniques and safety.

Discharge Oscillations in a Permanent Magnet Cylindrical Hall-Effect Thruster

NASA Technical Reports Server (NTRS)

Polzin, K. A.; Sooby, E. S.; Raitses, Y.; Merino, E.; Fisch, N. J.

2009-01-01

Measurements of the discharge current in a cylindrical Hall thruster are presented to quantify plasma oscillations and instabilities without introducing an intrusive probe into the plasma. The time-varying component of the discharge current is measured using a current monitor that possesses a wide frequency bandwidth and the signal is Fourier transformed to yield the frequency spectra present, allowing for the identification of plasma oscillations. The data show that the discharge current oscillations become generally greater in amplitude and complexity as the voltage is increased, and are reduced in severity with increasing flow rate. The breathing mode ionization instability is identified, with frequency as a function of discharge voltage not increasing with discharge voltage as has been observed in some traditional Hall thruster geometries, but instead following a scaling similar to a large-amplitude, nonlinear oscillation mode recently predicted in for annular Hall thrusters. A transition from lower amplitude oscillations to large relative fluctuations in the oscillating discharge current is observed at low flow rates and is suppressed as the mass flow rate is increased. A second set of peaks in the frequency spectra are observed at the highest propellant flow rate tested. Possible mechanisms that might give rise to these peaks include ionization instabilities and interactions between various oscillatory modes.

Hydrogeologic controls on groundwater discharge and nitrogen loads in a coastal watershed

USGS Publications Warehouse

Russoniello, Chrtopher J.; Konikow, Leonard F.; Kroeger, Kevin D.; Fernandez, Cristina; Andres, A. Scott; Michael, Holly A.

2016-01-01

Submarine groundwater discharge (SGD) is a small portion of the global water budget, but a potentially large contributor to coastal nutrient budgets due to high concentrations relative to stream discharge. A numerical groundwater flow model of the Inland Bays Watershed, Delaware, USA, was developed to identify the primary hydrogeologic factors that affect groundwater discharge rates and transit times to streams and bays. The distribution of groundwater discharge between streams and bays is sensitive to the depth of the water table below land surface. Higher recharge and reduced hydraulic conductivity raised the water table and increased discharge to streams relative to bays compared to the Reference case (in which 66% of recharge is discharged to streams). Increases to either factor decreased transit times for discharge to both streams and bays compared to the Reference case (in which mean transit times are 56.5 and 94.3 years, respectively), though sensitivity to recharge is greater. Groundwater-borne nitrogen loads were calculated from nitrogen concentrations measured in discharging fresh groundwater and modeled SGD rates. These loads combined with long SGD transit times suggest groundwater-borne nitrogen reductions and estuarine water quality improvements will lag decades behind implementation of efforts to manage nutrient sources. This work enhances understanding of the hydrogeologic controls on and uncertainties in absolute and relative rates and transit times of groundwater discharge to streams and bays in coastal watersheds.

Conceptual Design of the Nuclear Electronic Xenon Ion System (NEXIS)

NASA Technical Reports Server (NTRS)

Monheiser, Jeff; Polk, Jay; Randolph, Tom

2004-01-01

In support of the NEXIS program, Aerojet-Redmond Operations, with review and input from the JPL and Boeing, has completed the design for a development model (DM) discharge chamber assembly and main discharge cathode assembly. These efforts along with the work by JPL to develop the carbon-carbon-composite ion optics assembly have resulted in a complete ion engine design. The goal of the NEXIS program is to significantly advance the current state of the art by developing an ion engine capable of operating at an input power of 20kW, an Isp of 7500 sec and have a total xenon through put capability of 2000 kg. In this paper we will describe the methodology used to design the discharge chamber and cathode assemblies and describe the resulting final design. Specifics will include the concepts used for the mounting of the ion optics along with the concepts used for the gimbal mounts. In addition, we will present results of a vibrational analysis showing how the engine will respond to a typical Delta IV heavy vibration spectrum.

Quality of care after acute coronary syndromes in a prospective cohort with reasons for non-prescription of recommended medications.

PubMed

Auer, Reto; Gencer, Baris; Räber, Lorenz; Klingenberg, Roland; Carballo, Sebastian; Carballo, David; Nanchen, David; Cornuz, Jacques; Vader, John-Paul; Vogt, Pierre; Jüni, Peter; Matter, Christian M; Windecker, Stephan; Lüscher, Thomas Felix; Mach, François; Rodondi, Nicolas

2014-01-01

Adherence to guidelines is associated with improved outcomes of patients with acute coronary syndrome (ACS). Clinical registries developed to assess quality of care at discharge often do not collect the reasons for non-prescription for proven efficacious preventive medication in Continental Europe. In a prospective cohort of patients hospitalized for an ACS, we aimed at measuring the rate of recommended treatment at discharge, using pre-specified quality indicators recommended in cardiologic guidelines and including systematic collection of reasons for non-prescription for preventive medications. In a prospective cohort with 1260 patients hospitalized for ACS, we measured the rate of recommended treatment at discharge in 4 academic centers in Switzerland. Performance measures for medication at discharge were pre-specified according to guidelines, systematically collected for all patients and included in a centralized database. Six hundred and eighty eight patients(54.6%) were discharged with a main diagnosis of STEMI, 491(39%) of NSTEMI and 81(6.4%) of unstable angina. Mean age was 64 years and 21.3% were women. 94.6% were prescribed angiotensin converting enzyme inhibitors/angiotensin II receptor blockers at discharge when only considering raw prescription rates, but increased to 99.5% when including reasons non-prescription. For statins, rates increased from 98% to 98.6% when including reasons for non-prescription and for beta-blockers, from 82% to 93%. For aspirin, rates further increased from 99.4% to 100% and from to 99.8% to 100% for P2Y12 inhibitors. We found a very high adherence to ACS guidelines for drug prescriptions at discharge when including reasons for non-prescription to drug therapy. For beta-blockers, prescription rates were suboptimal, even after taking into account reason for non-prescription. In an era of improving quality of care to achieve 100% prescription rates at discharge unless contra-indicated, pre-specification of reasons for non-prescription for cardiovascular preventive medication permits to identify remaining gaps in quality of care at discharge. ClinicalTrials.gov NCT01000701.

49 CFR 180.403 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... or serviceability of the cargo tank. The term does not include cosmetic or minor surface degradation... capability including changes to equipment certified as part of an emergency discharge control system required...

49 CFR 180.403 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... or serviceability of the cargo tank. The term does not include cosmetic or minor surface degradation... capability including changes to equipment certified as part of an emergency discharge control system required...

49 CFR 180.403 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... or serviceability of the cargo tank. The term does not include cosmetic or minor surface degradation... capability including changes to equipment certified as part of an emergency discharge control system required...

49 CFR 180.403 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... or serviceability of the cargo tank. The term does not include cosmetic or minor surface degradation... capability including changes to equipment certified as part of an emergency discharge control system required...

Effect of La-doping on the structural, morphological and electrochemical properties of LiCoO2 nanoparticles using Sol-Gel technique

NASA Astrophysics Data System (ADS)

Farid, Ghulam; Murtaza, Ghulam; Umair, Muhammad; Shahab Arif, Hafiz; Saad Ali, Hafiz; Muhammad, Nawaz; Ahmad, Mukhtar

2018-05-01

Sol-Gel auto combustion technique was used to synthesis La3+substituted LiCoO2 lithium-rich cathode materials to improve the cycling performance and rate capability. Samples with different concentration of La containing LiCo1‑xLaxO2 (with 0 ≤ x ≤ 0.20) were chemically prepared and calcined the obtained powders at 850 °C for 6 h. Various techniques for the investigation of lanthanum behaviour in LiCoO2 have been utilised, such as x-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Near Edge x-ray absorption spectroscopy (NEXAS), Galvanostatic charge-discharge tests and cyclic voltammetry (CV). The formation of a hexagonal lattice of the α-NaFeO2 structure of LiCoO2, having space group R-3m is confirmed by x-ray diffraction analysis. FESEM results reveal that by increasing La contents the grain growth becomes distinct, well defined and smaller grains obtained. ATR-FTIR confirms the functional bonding in the prepared samples, as well XANES spectra reveals the electronic configuration valence state, chemical bonding character and local coordination of a specific atom. Maximum discharging capacities were observed in the La-doped material which is 182.38 mAhg‑1 and 56.2 mAhg‑1 at 0.1C and 5 C respectively and on average, this is more than 5% higher as compared to the pure LiCoO2. After 5C, the discharge capacity of the doped material at 0.1C can again reach 163.83 mAhg‑1, about 89% of the discharge capacity obtained in the first cycle. When 2032 type coin cells were cycled at a constant rate, an excellent cycling performance with capacity retention by a factor of ∼2 in comparison to the pristine LiCoO2 was observed for the composite cathode containing 4.0 mol% La. This reveals the structural stability induced by La doping. Remarkable improvement in reversibility and stability of the La-doped electrodes shown by cyclic voltammetry (CV). These composite cathodes might be very useful for high rate power applications.

Efficiency of lithium pacemaker batteries as a function of discharge rate and iodine:P2VP cathode composition

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

Helgeson, W.D.; Fester, K.E.

1980-01-01

Electrochemical discharge data for Li/I/sub 2/-P2VP pacemaker batteries at various discharge currents show the efficiency of the battery to be a function of discharge current. Depending on the iodine:P2VP cathode composition, the optimum current drain occurs between discharge currents of 100 to 200 /mu/a. As current drain is reduced to pacemaker application drains, 15-25 /mu/a, the efficiency of the Li/I/sub 2/-P2VP battery decreases. The loss in efficiency at pacemaker rates is attributed primarily to self-discharge. The efficiency of Li/I/sub 2/-P2VP batteries is improved by increasing the percent of iodine in the cathode. I/sub 2/:P2VP weight ratios of 10:1, 15:1 andmore » 20:1 have been discharged at various currents and the data indicate that there is significant improvement in efficiency at pacemaker rate in going from 10:1 to 20:1 cathode weight ratio. 2 refs.« less

Effect of Off-Body Laser Discharge on Drag Reduction of Hemisphere Cylinder in Supersonic Flow

NASA Technical Reports Server (NTRS)

Kianvashrad, Nadia; Knight, Doyle; Wilkinson, Stephen P.; Chou, Amanda; Horne, Robert A.; Herring, Gregory C.; Beeler, George B.; Jangda, Moazzam

2017-01-01

The interaction of an off-body laser discharge with a hemisphere cylinder in supersonic flow is investigated. The objectives are 1) experimental determination of the drag reduction and energetic efficiency of the laser discharge, and 2) assessment of the capability for accurate simulation of the interaction. The combined computational and experimental study comprises two phases. In the first phase, laser discharge in quiescent air was examined. The temporal behavior of the shock wave formed by the laser discharge was compared between experiment and simulation and good agreement is observed. In the second phase, the interaction of the laser discharge with a hemisphere cylinder was investigated numerically. Details of the pressure drag reduction and the physics of the interaction of the heated region with the bow shock are included. The drag reduction due to this interaction persisted for about five characteristic times where one characteristic time represents the time for the flow to move a distance equal to the hemisphere radius. The energetic efficiency of laser discharge for the case with 50 mJ energy absorbed by the gas is calculated as 3.22.

Patient outcomes following discharge from secure psychiatric hospitals: systematic review and meta-analysis

PubMed Central

Fazel, Seena; Fimińska, Zuzanna; Cocks, Christopher; Coid, Jeremy

2016-01-01

Background Secure hospitals are a high-cost, low-volume service consuming around a fifth of the overall mental health budget in England and Wales. Aims A systematic review and meta-analysis of adverse outcomes after discharge along with a comparison with rates in other clinical and forensic groups in order to inform public health and policy. Method We searched for primary studies that followed patients discharged from a secure hospital, and reported mortality, readmissions or reconvictions. We determined crude rates for all adverse outcomes. Results In total, 35 studies from 10 countries were included, involving 12 056 patients out of which 53% were violent offenders. The crude death rate for all-cause mortality was 1538 per 100 000 person-years (95% CI 1175–1901). For suicide, the crude death rate was 325 per 100 000 person-years (95% CI 235–415). The readmission rate was 7208 per 100 000 person-years (95% CI 5916–8500). Crude reoffending rates were 4484 per 100 000 person-years (95% CI 3679–5287), with lower rates in more recent studies. Conclusions There is some evidence that patients discharged from forensic psychiatric services have lower offending outcomes than many comparative groups. Services could consider improving interventions aimed at reducing premature mortality, particularly suicide, in discharged patients. PMID:26729842

The incidence and severity of errors in pharmacist-written discharge medication orders.

PubMed

Onatade, Raliat; Sawieres, Sara; Veck, Alexandra; Smith, Lindsay; Gore, Shivani; Al-Azeib, Sumiah

2017-08-01

Background Errors in discharge prescriptions are problematic. When hospital pharmacists write discharge prescriptions improvements are seen in the quality and efficiency of discharge. There is limited information on the incidence of errors in pharmacists' medication orders. Objective To investigate the extent and clinical significance of errors in pharmacist-written discharge medication orders. Setting 1000-bed teaching hospital in London, UK. Method Pharmacists in this London hospital routinely write discharge medication orders as part of the clinical pharmacy service. Convenient days, based on researcher availability, between October 2013 and January 2014 were selected. Pre-registration pharmacists reviewed all discharge medication orders written by pharmacists on these days and identified discrepancies between the medication history, inpatient chart, patient records and discharge summary. A senior clinical pharmacist confirmed the presence of an error. Each error was assigned a potential clinical significance rating (based on the NCCMERP scale) by a physician and an independent senior clinical pharmacist, working separately. Main outcome measure Incidence of errors in pharmacist-written discharge medication orders. Results 509 prescriptions, written by 51 pharmacists, containing 4258 discharge medication orders were assessed (8.4 orders per prescription). Ten prescriptions (2%), contained a total of ten erroneous orders (order error rate-0.2%). The pharmacist considered that one error had the potential to cause temporary harm (0.02% of all orders). The physician did not rate any of the errors with the potential to cause harm. Conclusion The incidence of errors in pharmacists' discharge medication orders was low. The quality, safety and policy implications of pharmacists routinely writing discharge medication orders should be further explored.

Inhospital and Post-discharge Changes in Renal Function After Transcatheter Aortic Valve Replacement.

PubMed

Blair, John E A; Brummel, Kent; Friedman, Julie L; Atri, Prashant; Sweis, Ranya N; Russell, Hyde; Ricciardi, Mark J; Malaisrie, S Chris; Davidson, Charles J; Flaherty, James D

2016-02-15

The aim of this study was to determine the influence of inhospital and post-discharge worsening renal function (WRF) on prognosis after transcatheter aortic valve replacement (TAVR). Severe chronic kidney disease and inhospital WRF are both associated with poor outcomes after TAVR. There are no data available on post-discharge WRF and outcomes. This was a single-center study evaluating all TAVR from June 1, 2008, to June 31, 2014. WRF was defined as an increase in serum creatinine of ≥0.3 mg/dl. Inhospital WRF was measured from day 0 until discharge or day 7 if the hospitalization was >7 days. Post-discharge WRF was measured at 30 days after discharge. Descriptive statistics, Kaplan-Meier time-to-event analysis, and multivariate logistic regression were used. In a series of 208 patients who underwent TAVR, 204 with complete renal function data were used in the inhospital analysis and 168 who returned for the 30-day follow-up were used in the post-discharge analysis. Inhospital WRF was seen in 28%, whereas post-discharge WRF in 12%. Inhospital and post-discharge WRF were associated with lower rates of survival; however, after multivariate analysis, only post-discharge WRF remained a predictor of 1-year mortality (hazard ratio 1.18, p = 0.030 for every 1 mg/dl increase in serum creatinine). In conclusion, the rate of inhospital WRF is higher than the rate of post-discharge WRF after TAVR, and post-discharge WRF is more predictive of mortality than inhospital WRF. Copyright © 2016 Elsevier Inc. All rights reserved.

Nanosized LiM YMn 2- YO 4 (M = Cr, Co and Ni) spinels synthesized by a sucrose-aided combustion method . Structural characterization and electrochemical properties

NASA Astrophysics Data System (ADS)

Amarilla, J. M.; Rojas, R. M.; Pico, F.; Pascual, L.; Petrov, K.; Kovacheva, D.; Lazarraga, M. G.; Lejona, I.; Rojo, J. M.

Spinels of composition LiM YMn 2- YO 4, M = Cr 3+, Co 3+, or Ni 2+, Y = 0.1 and 1 for the Cr and Co dopants, Y = 0.05 and 0.5 for the Ni sample, have been synthesized by a sucrose-aided combustion method. The samples as prepared require of an additional thermal treatment at 700 °C, 1 h to get stoichiometric single-phase spinels. The samples consist of aggregated particles of small size (45-50 nm) as deduced from transmission electron microscopy and X-ray powder diffraction. The electrochemical behaviour of the six spinels as cathodes in lithium cells has been analysed at 5 and 4 V under high current, 1 C rate. At 5 V the discharge capacity of LiNi 0.5Mn 1.5O 4 is higher than the one shown by LiCrMnO 4 and LiCoMnO 4, and it shows an elevated cyclability, i.e. capacity retention of 85.3% after 100 cycles. At 4 V the discharge capacity is similar for LiNi 0.05Mn 1.95O 4, LiCr 0.1Mn 1.9O 4 and LiCo 0.1Mn 1.9O 4, and all the three spinels show similar and very high cyclability, i.e. capacity retention >90% after 100 cycles. The spinels preserve their starting capacity up to currents as high as 2 C rate. The nanometric size of the samples explains the high rate capability of the synthesized spinels.

Carbon-Coated, Diatomite-Derived Nanosilicon as a High Rate Capable Li-ion Battery Anode

PubMed Central

Campbell, Brennan; Ionescu, Robert; Tolchin, Maxwell; Ahmed, Kazi; Favors, Zachary; Bozhilov, Krassimir N.; Ozkan, Cengiz S.; Ozkan, Mihrimah

2016-01-01

Silicon is produced in a variety of ways as an ultra-high capacity lithium-ion battery (LIB) anode material. The traditional carbothermic reduction process required is expensive and energy-intensive; in this work, we use an efficient magnesiothermic reduction to convert the silica-based frustules within diatomaceous earth (diatomite, DE) to nanosilicon (nanoSi) for use as LIB anodes. Polyacrylic acid (PAA) was used as a binder for the DE-based nanoSi anodes for the first time, being attributed for the high silicon utilization under high current densities (up to 4C). The resulting nanoSi exhibited a high BET specific surface area of 162.6 cm2 g−1, compared to a value of 7.3 cm2 g−1 for the original DE. DE contains SiO2 architectures that make ideal bio-derived templates for nanoscaled silicon. The DE-based nanoSi anodes exhibit good cyclability, with a specific discharge capacity of 1102.1 mAh g−1 after 50 cycles at a C-rate of C/5 (0.7 A gSi−1) and high areal loading (2 mg cm−2). This work also demonstrates the fist rate capability testing for a DE-based Si anode; C-rates of C/30 - 4C were tested. At 4C (14.3 A gSi−1), the anode maintained a specific capacity of 654.3 mAh g−1 – nearly 2x higher than graphite’s theoretical value (372 mAh g−1). PMID:27713474

Carbon-Coated, Diatomite-Derived Nanosilicon as a High Rate Capable Li-ion Battery Anode

NASA Astrophysics Data System (ADS)

Campbell, Brennan; Ionescu, Robert; Tolchin, Maxwell; Ahmed, Kazi; Favors, Zachary; Bozhilov, Krassimir N.; Ozkan, Cengiz S.; Ozkan, Mihrimah

2016-10-01

Silicon is produced in a variety of ways as an ultra-high capacity lithium-ion battery (LIB) anode material. The traditional carbothermic reduction process required is expensive and energy-intensive; in this work, we use an efficient magnesiothermic reduction to convert the silica-based frustules within diatomaceous earth (diatomite, DE) to nanosilicon (nanoSi) for use as LIB anodes. Polyacrylic acid (PAA) was used as a binder for the DE-based nanoSi anodes for the first time, being attributed for the high silicon utilization under high current densities (up to 4C). The resulting nanoSi exhibited a high BET specific surface area of 162.6 cm2 g-1, compared to a value of 7.3 cm2 g-1 for the original DE. DE contains SiO2 architectures that make ideal bio-derived templates for nanoscaled silicon. The DE-based nanoSi anodes exhibit good cyclability, with a specific discharge capacity of 1102.1 mAh g-1 after 50 cycles at a C-rate of C/5 (0.7 A gSi-1) and high areal loading (2 mg cm-2). This work also demonstrates the fist rate capability testing for a DE-based Si anode; C-rates of C/30 - 4C were tested. At 4C (14.3 A gSi-1), the anode maintained a specific capacity of 654.3 mAh g-1 - nearly 2x higher than graphite’s theoretical value (372 mAh g-1).

Demonstration of a high repetition rate capillary discharge waveguide

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

Gonsalves, A. J., E-mail: ajgonsalves@lbl.gov; Pieronek, C.; Daniels, J.

2016-01-21

A hydrogen-filled capillary discharge waveguide operating at kHz repetition rates is presented for parameters relevant to laser plasma acceleration (LPA). The discharge current pulse was optimized for erosion mitigation with laser guiding experiments and MHD simulation. Heat flow simulations and measurements showed modest temperature rise at the capillary wall due to the average heat load at kHz repetition rates with water-cooled capillaries, which is promising for applications of LPAs such as high average power radiation sources.

Stream-Groundwater Interaction Buffers Seasonal Changes in Urban Stream Water Quality

NASA Astrophysics Data System (ADS)

Ledford, S. H.; Lautz, L. K.

2013-12-01

Urban streams in the northeastern United States have large road salt inputs during winter, increased nonpoint sources of inorganic nitrogen, and decreased short-term and permanent storage of nutrients. Meadowbrook Creek, a first order stream in Syracuse, New York, flows along a negative urbanization gradient, from a channelized and armored stream running through the middle of a roadway to a pool-riffle stream meandering through a broad, vegetated floodplain with a riparian aquifer. In this study we investigated how reconnection to groundwater and introduction of riparian vegetation impacted surface water chemistry by making bi-weekly longitudinal surveys of stream water chemistry in the creek from May 2012 until June 2013. Chloride concentrations in the upstream, urban reach of Meadowbrook Creek were strongly influenced by discharge of road salt to the creek during snow melt events in winter and by the chemistry of water draining an upstream retention basin in summer. Chloride concentrations ranged from 161.2 mg/L in August to 2172 mg/L in February. Chloride concentrations in the downstream, 'connected' reach had less temporal variation, ranging from 252.0 mg/L in August to 1049 mg/L in January, and were buffered by groundwater discharge, as the groundwater chloride concentrations during the sampling period ranged from 84.0 to 655.4 mg/L. Groundwater discharge resulted in higher chloride concentrations in summer and lower concentrations in winter in the connected reach relative to the urban reach, minimizing annual variation. In summer, there was little-to-no nitrate in the urban reach due to a combination of limited sources and high primary productivity. In contrast, during the summer, nitrate concentrations reached over 1 mg N/L in the connected reach due to the presence of riparian vegetation and lower nitrate uptake due to cooler temperatures and shading. During the winter, when temperatures fell below freezing, nitrate concentrations in the urban reach increased to around 0.58 mg N/L, but were still lower than the connected reach, which averaged 0.88 mg N/L. Groundwater discharge rates were measured longitudinally along the creek during a constant rate Rhodamine WT injection and also confirmed qualitatively by longitudinal changes in stream sulfate and δ18O. The buffering capability of groundwater discharge in urban systems has implications for managers trying to mitigate the effects of urbanization on surface water.

Sensitivity of 30-cm mercury bombardment ion thruster characteristics to accelerator grid design

NASA Technical Reports Server (NTRS)

Rawlin, V. K.

1978-01-01

The design of ion optics for bombardment thrusters strongly influences overall performance and lifetime. The operation of a 30 cm thruster with accelerator grid open area fractions ranging from 43 to 24 percent, was evaluated and compared with experimental and theoretical results. Ion optics properties measured included the beam current extraction capability, the minimum accelerator grid voltage to prevent backstreaming, ion beamlet diameter as a function of radial position on the grid and accelerator grid hole diameter, and the high energy, high angle ion beam edge location. Discharge chamber properties evaluated were propellant utilization efficiency, minimum discharge power per beam amp, and minimum discharge voltage.

Numerical simulation of narrow bipolar electromagnetic pulses generated by thunderstorm discharges

NASA Astrophysics Data System (ADS)

Bochkov, E. I.; Babich, L. P.; Kutsyk, I. M.

2013-07-01

Using the concept of avalanche relativistic runaway electrons (REs), we perform numerical simulations of compact intracloud discharge (CID) as a generator of powerful natural electromagnetic pulses (EMPs) in the HF-VHF range, called narrow bipolar pulses (NBPs). For several values of the field overvoltage and altitude at which the discharge develops, the numbers of seed electrons initiating the avalanche are evaluated, with which the calculated EMP characteristics are consistent with the measured NBP parameters. We note shortcomings in the hypothesis assuming participation of cosmic ray air showers in avalanche initiation. The discharge capable of generating NBPs produces REs in numbers close to those in the source of terrestrial γ-ray flashes (TGFs), which can be an argument in favor of a unified NBP and TGF source.

Motor unit recruitment in human biceps brachii during sustained voluntary contractions.

PubMed

Riley, Zachary A; Maerz, Adam H; Litsey, Jane C; Enoka, Roger M

2008-04-15

The purpose of the study was to examine the influence of the difference between the recruitment threshold of a motor unit and the target force of the sustained contraction on the discharge of the motor unit at recruitment. The discharge characteristics of 53 motor units in biceps brachii were recorded after being recruited during a sustained contraction. Some motor units (n = 22) discharged action potentials tonically after being recruited, whereas others (n = 31) discharged intermittent trains of action potentials. The two groups of motor units were distinguished by the difference between the recruitment threshold of the motor unit and the target force for the sustained contraction: tonic, 5.9 +/- 2.5%; intermittent, 10.7 +/- 2.9%. Discharge rate for the tonic units decreased progressively (13.9 +/- 2.7 to 11.7 +/- 2.6 pulses s(-1); P = 0.04) during the 99 +/- 111 s contraction. Train rate, train duration and average discharge rate for the intermittent motor units did not change across 211 +/- 153 s of intermittent discharge. The initial discharge rate at recruitment during the sustained contraction was lower for the intermittent motor units (11.0 +/- 3.3 pulses s(-1)) than the tonic motor units (13.7 +/- 3.3 pulses s(-1); P = 0.005), and the coefficient of variation for interspike interval was higher for the intermittent motor units (34.6 +/- 12.3%) than the tonic motor units (21.2 +/- 9.4%) at recruitment (P = 0.001) and remained elevated for discharge duration (34.6 +/- 9.2% versus 19.1 +/- 11.7%, P < 0.001). In an additional experiment, 12 motor units were recorded at two different target forces below recruitment threshold (5.7 +/- 1.9% and 10.5 +/- 2.4%). Each motor unit exhibited the two discharge patterns (tonic and intermittent) as observed for the 53 motor units. The results suggest that newly recruited motor units with recruitment thresholds closer to the target force experienced less synaptic noise at the time of recruitment that resulted in them discharging action potentials at more regular and greater rates than motor units with recruitment thresholds further from the target force.

Current Trends in Discharge Disposition and Post-discharge Care After Total Joint Arthroplasty.

PubMed

Tarity, T David; Swall, Marion M

2017-09-01

The purpose of this manuscript is to review published literature over the last 5 years to assess recent trends and influencing factors regarding discharge disposition and post-discharge care following total joint arthroplasty. We evaluated instruments proposed to predict a patient's discharge disposition and summarize reports investigating the safety in sending more patients home by reviewing complications and readmission rates. Current literature supports decreased length of hospital stay and increased discharge to home with cost savings and stable readmission rates. Surgeons with defined clinical pathways and those who shape patient expectations may more effectively control costs than those without defined pathways. Further research is needed analyzing best practices in care coordination, managing patient expectations, and cost-effective analysis of home discharge while at the same time ensuring patient outcomes are optimized following total joint arthroplasty.

Highly crumpled solar reduced graphene oxide electrode for supercapacitor application

NASA Astrophysics Data System (ADS)

Mohanapriya, K.; Ahirrao, Dinesh J.; Jha, Neetu

2018-04-01

Highly crumpled solar reduced graphene oxide (CSRGO) was synthesized by simple and rapid method through freezing the solar reduced graphene oxide aqueous suspension using liquid nitrogen and used as electrode material for supercapacitor application. This electrode material was characterized by transmission electron microscope (TEM), X-Ray diffractometer (XRD) and Raman Spectroscopy techniques to understand the morphology and structure. The electrochemical performance was studied by cyclic voltammetry (CV), galvanostatic charge/discharge (CD) and electrochemical impedance spectroscopy (EIS) using 6M KOH electrolyte. The CSRGO exhibit high specifc capacitance of 210.1 F g-1 at the current density of 0.5 A g-1 and shows excellent rate capability. These features make the CSRGO material as promising electrode for high-performance supercapacitors.

A heat-pulse flowmeter for measuring minimal discharge rates in boreholes

USGS Publications Warehouse

Hess, A.E.

1982-01-01

The U.S. Geological Survey has tested a borehole-configured heat-pulse flowmeter which has good low-velocity flow-measuring sensitivity. The flowmeter was tested in the laboratory in 51-, 102-, and 152-millimeter-diameter columns using water velocities ranging from 0.35 to 250 millimeters per second. The heat-pulse flowmeter also was tested in a 15-meter-deep granite test pit with controlled water flow, and in a 58-meter-deep borehole in sedimentary materials. The flowmeter's capability to detect and measure naturally occurring, low-velocity, thermally induced convection currents in boreholes was demonstrated. Further improvements to the heat-pulse-flowmeter system are needed to increase its reliability and improve its response through four-conductor logging cable.

Controlled synthesis of hollow octahedral ZnCo2O4 nanocages assembled from ultrathin 2D nanosheets for enhanced lithium storage.

PubMed

Liu, Beihong; Liu, Hui; Liang, Mengfang; Liu, Lixiang; Lv, Zhaolin; Zhou, Hang; Guo, Hong

2017-11-16

Hollow octahedral ZnCo 2 O 4 nanocages assembled from ultrathin 2D nanosheets are prepared through facile fast simultaneous coordinating etching and thermal processes. Electrochemical results show that the hollow octahedral ZnCo 2 O 4 nanocage is an outstanding anode material for LIBs with a high reversible discharge capacity of 1025 mA h g -1 at 500 mA g -1 after 200 cycles, and an outstanding rate capability of 525 mA h g -1 at 4 A g -1 . Moreover, this simple, low cost and fast process could be useful for the construction of many other hollow advanced materials for supercapacitors, sensors and other novel energy and environmental applications.

Free-standing porous manganese dioxide/graphene composite films for high performance supercapacitors.

PubMed

Guo, Wang-Huan; Liu, Teng-Jiao; Jiang, Peng; Zhang, Zhan-Jun

2015-01-01

A simple hard template method and hydrothermal process have been employed to fabricate a self-standing hierarchical porous MnO2/graphene film. Thus-constructed electrode materials for binder-free supercapacitors exhibit a high specific capacitance of 266.3 F g(-1) at the density of 0.2 A g(-1). Moreover, the two-electrode device demonstrates an excellent rate capability and cycling stability with capacitance retention of 85.1% after 2000 charge-discharge cycles at a current density of 1 A g(-1). The porous nanostructured design can effectively improve the specific surface areas and account for the shorter relaxation time for the electrodes, resulting in a high electrochemical performance. Copyright © 2014 Elsevier Inc. All rights reserved.

An agent-based model for queue formation of powered two-wheelers in heterogeneous traffic

NASA Astrophysics Data System (ADS)

Lee, Tzu-Chang; Wong, K. I.

2016-11-01

This paper presents an agent-based model (ABM) for simulating the queue formation of powered two-wheelers (PTWs) in heterogeneous traffic at a signalized intersection. The main novelty is that the proposed interaction rule describing the position choice behavior of PTWs when queuing in heterogeneous traffic can capture the stochastic nature of the decision making process. The interaction rule is formulated as a multinomial logit model, which is calibrated by using a microscopic traffic trajectory dataset obtained from video footage. The ABM is validated against the survey data for the vehicular trajectory patterns, queuing patterns, queue lengths, and discharge rates. The results demonstrate that the proposed model is capable of replicating the observed queue formation process for heterogeneous traffic.

Design concepts of high power bipolar rechargeable lithium battery

NASA Technical Reports Server (NTRS)

Shen, David H.; Halpert, Gerald

1993-01-01

The present study shows that current bipolar Li/TiS2 batteries using a 0.38 mm thick TiS2 bipolar plate can yield moderate specific power and also high specific energy battery. The computer design studies project that a 100 V, 10 A h bipolar Li/TiS2 battery can achieve 150 W h/kg, 210 W h/l, and 150 W/kg. The unoptimized experimental bipolar Li/TiS2 batteries (3 cells, 90 mA h) exhibited 47 W h/kg, 90 W h/l, and 140 W/kg. Preliminary results on the cycleability of the bipolar batteries are demonstrated. The results also show that enhanced rate capability can be achieved by using pulse discharge and longer rest period between pulses.

Liquid-metal-fed Pulsed Plasma Thrusters for In-space Propulsion

NASA Technical Reports Server (NTRS)

Markusic, Thomas E.

2004-01-01

Liquid metal propellants may provide a path toward more reliable and efficient pulsed plasma thrusters (PPTs). Conceptual thruster designs which eliminate the need for high current switches and propellant metering valves are described. Propellant loading techniques are suggested that show promise to increase thruster propellant utilization, dynamic, and electrical efficiency. Calibration results from a compact, electromagnetically-pumped propellant feed system are presented. Results for lithium and gallium propellants show capability to meter propellant at flow rates up to 10 +/- 0.1 mg/s. Experiments investigating the initiation of arc discharges using liquid metal droplets are presented. High speed photography and laser interferometry provide spatially and temporally resolved information on the decomposition of liquid metal droplets , and the evolution of the accelerating current channel.

A low-energy metal-ion source for primary ion deposition and accelerated ion doping during molecular-beam epitaxy

NASA Astrophysics Data System (ADS)

Hasan, M.-A.; Knall, J.; Barnett, S. A.; Rockett, A.; Sundgren, J.-E.

1987-10-01

A single-grid electron-impact ultrahigh vacuum (UHV) compatible low-energy ion gun capable of operating with a low vapor pressure solid source material such as In is presented. The gun consists of a single chamber which integrates the functions of an effusion cell, a vapor transport tube, and a glow discharge ionizer. The initial results of experiments designed to study the role of ion/surface interactions during nucleation and the early stages of crystal growth in UHV revealed that, for deposition on amorphous substrates, the use of a partially ionized In(+) beam resulted in a progressive shift towards larger island sizes, a decreased rate of secondary nucleation, and a more uniform island size distribution.

Fluctuations in isometric muscle force can be described by one linear projection of low-frequency components of motor unit discharge rates

PubMed Central

Negro, Francesco; Holobar, Aleš; Farina, Dario

2009-01-01

The aim of the study was to investigate the relation between linear transformations of motor unit discharge rates and muscle force. Intramuscular (wire electrodes) and high-density surface EMG (13 × 5 electrode grid) were recorded from the abductor digiti minimi muscle of eight healthy men during 60 s contractions at 5%, 7.5% and 10% of the maximal force. Spike trains of a total of 222 motor units were identified from the EMG recordings with decomposition algorithms. Principal component analysis of the smoothed motor unit discharge rates indicated that one component (first common component, FCC) described 44.2 ± 7.5% of the total variability of the smoothed discharge rates when computed over the entire contraction interval and 64.3 ± 10.2% of the variability when computed over 5 s intervals. When the FCC was computed from four or more motor units per contraction, it correlated with the force produced by the muscle (62.7 ± 10.1%) by a greater degree (P < 0.001) than the smoothed discharge rates of individual motor units (41.4 ± 7.8%). The correlation between FCC and the force signal increased up to 71.8 ± 13.1% when the duration and the shape of the smoothing window for discharge rates were similar to the average motor unit twitch force. Moreover, the coefficients of variation (CoV) for the force and for the FCC signal were correlated in all subjects (R2 range = 0.14–0.56; P < 0.05) whereas the CoV for force was correlated to the interspike interval variability in only one subject (R2= 0.12; P < 0.05). Similar results were further obtained from measures on the tibialis anterior muscle of an additional eight subjects during contractions at forces up to 20% of the maximal force (e.g. FCC explained 59.8 ± 11.0% of variability of the smoothed discharge rates). In conclusion, one signal captures most of the underlying variability of the low-frequency components of motor unit discharge rates and explains large part of the fluctuations in the motor output during isometric contractions. PMID:19840996

Fluctuations in isometric muscle force can be described by one linear projection of low-frequency components of motor unit discharge rates.

PubMed

Negro, Francesco; Holobar, Ales; Farina, Dario

2009-12-15

The aim of the study was to investigate the relation between linear transformations of motor unit discharge rates and muscle force. Intramuscular (wire electrodes) and high-density surface EMG (13 x 5 electrode grid) were recorded from the abductor digiti minimi muscle of eight healthy men during 60 s contractions at 5%, 7.5% and 10% of the maximal force. Spike trains of a total of 222 motor units were identified from the EMG recordings with decomposition algorithms. Principal component analysis of the smoothed motor unit discharge rates indicated that one component (first common component, FCC) described 44.2 +/- 7.5% of the total variability of the smoothed discharge rates when computed over the entire contraction interval and 64.3 +/- 10.2% of the variability when computed over 5 s intervals. When the FCC was computed from four or more motor units per contraction, it correlated with the force produced by the muscle (62.7 +/- 10.1%) by a greater degree (P < 0.001) than the smoothed discharge rates of individual motor units (41.4 +/- 7.8%). The correlation between FCC and the force signal increased up to 71.8 +/- 13.1% when the duration and the shape of the smoothing window for discharge rates were similar to the average motor unit twitch force. Moreover, the coefficients of variation (CoV) for the force and for the FCC signal were correlated in all subjects (R(2) range = 0.14-0.56; P < 0.05) whereas the CoV for force was correlated to the interspike interval variability in only one subject (R(2) = 0.12; P < 0.05). Similar results were further obtained from measures on the tibialis anterior muscle of an additional eight subjects during contractions at forces up to 20% of the maximal force (e.g. FCC explained 59.8 +/- 11.0% of variability of the smoothed discharge rates). In conclusion, one signal captures most of the underlying variability of the low-frequency components of motor unit discharge rates and explains large part of the fluctuations in the motor output during isometric contractions.

Nanostructured Si(₁-x)Gex for tunable thin film lithium-ion battery anodes.

PubMed

Abel, Paul R; Chockla, Aaron M; Lin, Yong-Mao; Holmberg, Vincent C; Harris, Justin T; Korgel, Brian A; Heller, Adam; Mullins, C Buddie

2013-03-26

Both silicon and germanium are leading candidates to replace the carbon anode of lithium ions batteries. Silicon is attractive because of its high lithium storage capacity while germanium, a superior electronic and ionic conductor, can support much higher charge/discharge rates. Here we investigate the electronic, electrochemical and optical properties of Si(1-x)Gex thin films with x = 0, 0.25, 0.5, 0.75, and 1. Glancing angle deposition provided amorphous films of reproducible nanostructure and porosity. The film's composition and physical properties were investigated by X-ray photoelectron spectroscopy, four-point probe conductivity, Raman, and UV-vis absorption spectroscopy. The films were assembled into coin cells to test their electrochemical properties as a lithium-ion battery anode material. The cells were cycled at various C-rates to determine the upper limits for high rate performance. Adjusting the composition in the Si(1-x)Gex system demonstrates a trade-off between rate capability and specific capacity. We show that high-capacity silicon anodes and high-rate germanium anodes are merely the two extremes; the composition of Si(1-x)Gex alloys provides a new parameter to use in electrode optimization.

Discharge Processes and 30-Day Readmission Rates of Patients Hospitalized for Heart Failure on General Medicine and Cardiology Services.

PubMed

Salata, Brian M; Sterling, Madeline R; Beecy, Ashley N; Ullal, Ajayram V; Jones, Erica C; Horn, Evelyn M; Goyal, Parag

2018-05-01

Given high rates of heart failure (HF) hospitalizations and widespread adoption of the hospitalist model, patients with HF are often cared for on General Medicine (GM) services. Differences in discharge processes and 30-day readmission rates between patients on GM and those on Cardiology during the contemporary hospitalist era are unknown. The present study compared discharge processes and 30-day readmission rates of patients with HF admitted on GM services and those on Cardiology services. We retrospectively studied 926 patients discharged home after HF hospitalization. The primary outcome was 30-day all-cause readmission after discharge from index hospitalization. Although 60% of patients with HF were admitted to Cardiology services, 40% were admitted to GM services. Prevalence of cardiovascular and noncardiovascular co-morbidities were similar between patients admitted to GM services and Cardiology services. Discharge summaries for patients on GM services were less likely to have reassessments of ejection fraction, new study results, weights, discharge vital signs, discharge physical examinations, and scheduled follow-up cardiologist appointments. In a multivariable regression analysis, patients on GM services were more likely to experience 30-day readmissions compared with those on Cardiology services (odds ratio 1.43 95% confidence interval [1.05 to 1.96], p = 0.02). In conclusion, outcomes are better among those admitted to Cardiology services, signaling the need for studies and interventions focusing on noncardiology hospital providers that care for patients with HF. Copyright © 2018 Elsevier Inc. All rights reserved.

Plasma Diagnostics For The Investigation of Silane Based Glow Discharge Deposition Processes

NASA Astrophysics Data System (ADS)

Mataras, Dimitrios

2001-10-01

In this work is presented the study of microcrystalline silicon PECVD process through highly diluted silane in hydrogen discharges. The investigation is performed by applying different non intrusive plasma diagnostics (electrical, optical, mass spectrometric and laser interferometric measurements). Each of these measurements is related to different plasma sub-processes (gas physics, plasma chemistry and plasma surface interaction) and compose a complete set, proper for the investigation of the effect of external discharge parameters on the deposition processes. In the specific case these plasma diagnostics are applied for prospecting the optimal experimental conditions from the ic-Si:H deposition rate point of view. Namely, the main characteristics of the effect of frequency, discharge geometry, power consumption and total gas pressure on the deposition process are presented successively. Special attention is given to the study of the frequency effect (13.56 MHz 50 MHz) indicating that the correct way to compare results of different driving frequency discharges is by maintaining constant the total power dissipation in the discharge. The important role of frequency in the achievement of high deposition rates and on the optimization of all other parameters is underlined. Finally, the proper combination of experimental conditions that result from the optimal choice of each of the above-mentioned discharge parameters and lead to high microcrystalline silicon deposition rates (7.5 Å/sec) is presented. The increase of silane dissociation rate towards neutral radicals (frequency effect), the contribution of highly sticking to the surface radicals (discharge geometry optimum) and the controlled production of higher radicals through secondary gas phase reactions (total gas pressure), are presented as prerequisites for the achievement of high deposition rates.

Mo-doped SnO2 mesoporous hollow structured spheres as anode materials for high-performance lithium ion batteries

NASA Astrophysics Data System (ADS)

Wang, Xuekun; Li, Zhaoqiang; Zhang, Zhiwei; Li, Qun; Guo, Enyan; Wang, Chengxiang; Yin, Longwei

2015-02-01

We designed a facile infiltration route to synthesize mesoporous hollow structured Mo doped SnO2 using silica spheres as templates. It is observed that Mo is uniformly incorporated into SnO2 lattice in the form of Mo6+. The as-prepared mesoporous Mo-doped SnO2 LIBs anodes exhibit a significantly improved electrochemical performance with good cycling stability, high specific capacity and high rate capability. The mesoporous hollow Mo-doped SnO2 sample with 14 at% Mo doping content displays a specific capacity of 801 mA h g-1 after 60 cycles at a current density of 100 mA g-1, about 1.66 times higher than that of the pure SnO2 hollow sample. In addition, even if the current density is as high as 1600 mA g-1 after 60 cycles, it could still retain a stable specific capacity of 530 mA h g-1, exhibiting an extraordinary rate capability. The greatly improved electrochemical performance of the Mo-doped mesoporous hollow SnO2 sample could be attributed to the following factors. The large surface area and hollow structure can significantly enhance structural integrity by acting as mechanical buffer, effectively alleviating the volume changes generated during the lithiation/delithiation process. The incorporation of Mo into the lattice of SnO2 improves charge transfer kinetics and results in a faster Li+ diffusion rate during the charge-discharge process.

Age and admission times as predictive factors for failure of admissions to discharge-stream short-stay units.

PubMed

Shetty, Amith L; Shankar Raju, Savitha Banagar; Hermiz, Arsalan; Vaghasiya, Milan; Vukasovic, Matthew

2015-02-01

Discharge-stream emergency short-stay units (ESSU) improve ED and hospital efficiency. Age of patients and time of hospital presentations have been shown to correlate with increasing complexity of care. We aim to determine whether an age and time cut-off could be derived to subsequently improve short-stay unit success rates. We conducted a retrospective audit on 6703 (5522 inclusions) patients admitted to our discharge-stream short-stay unit. Patients were classified as appropriate or inappropriate admissions, and deemed successful if discharged out of the unit within 24 h; and failures if they needed inpatient admission into the hospital. We calculated short-stay unit length of stay for patients in each of these groups. A 15% failure rate was deemed as acceptable key performance indicator (KPI) for our unit. There were 197 out of 4621 (4.3%, 95% CI 3.7-4.9%) patients up to the age of 70 who failed admission to ESSU compared with 67 out of 901 (7.4%, 95% CI 5.9-9.3%, P < 0.01) of patients over the age of 70, reflecting an increased failure rate in geriatric population. When grouped according to times of admission to the ESSU (in-office 06.00-22.00 hours vs out-of-office 22.00-06.00 hours) no significant difference rates in discharge failure (4.7% vs 5.2%, P = 0.46) were noted. Patients >70 years of age have higher rates of failure after admission to discharge-stream ESSU. Although in appropriately selected discharge-stream patients, no age group or time-band of presentation was associated with increased failure rate beyond the stipulated KPI. © 2014 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

Final Report: Levitated Dipole Experiment

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

Kesner, Jay; Mauel, Michael

2013-03-10

Since the very first experiments with the LDX, research progress was rapid and significant. Initial experiments were conducted with the high-field superconducting coil suspended by three thin rods. These experiments produced long-pulse, quasi-steady-state microwave discharges, lasting more than 10 s, having peak beta values of 20% [Garnier et al., Physics of Plasmas, 13 (2006) 056111]. High- beta, near steady-state discharges have been maintained in LDX for more than 20 seconds, and this capability made LDX the longest pulse fusion confinement experiment operating in the U.S. fusion program. A significant measure of progress in the LDX research program was the routinemore » investigation of plasma confinement with a magnetically-levitated dipole and the resulting observations of confinement improvement. In both supported and levitated configurations, detailed measurements were made of discharge evolution, plasma dynamics and instability, and the roles of gas fueling, microwave power deposition profiles, and plasma boundary shape. High-temperature plasma was created by multi frequency electron cyclotron resonance heating at 2.45 GHz, 6.4 GHz, 10.5 GHz and 28 GHz allowing control of heating profiles. Depending upon neutral fueling rates, the LDX discharges contain a fraction of energetic electrons, with mean energies above 50 keV. Depending on whether or not the superconducting dipole was levitated or supported, the peak thermal electron temperature was estimated to exceed 500 eV and peak densities to approach 1e18 m -3. We have found that levitation causes a strong inwards density pinch [Boxer et al., Nature Physics, 6 (2010) 207] and we have observed the central plasma density increase dramatically indicating a significant improvement in the confinement of a thermal plasma species.« less

Lithium-sulfur dioxide batteries on Mars rovers

NASA Technical Reports Server (NTRS)

Ratnakumar, Bugga V.; Smart, M. C.; Ewell, R. C.; Whitcanack, L. D.; Kindler, A.; Narayanan, S. R.; Surampudi, S.

2004-01-01

NASA's 2003 Mars Exploration Rover (MER) missions, Spirit and Opportunity, have been performing exciting surface exploration studies for the past six months. These two robotic missions were aimed at examining the presence of water and, thus, any evidence of life, and at understanding the geological conditions of Mars, These rovers have been successfully assisted by primary lithium-sulfur dioxide batteries during the critical entry, descent, and landing (EDL) maneuvers. These batteries were located on the petals of the lander, which, unlike in the Mars Pathfinder mission, was designed only to carry the rover. The selection of the lithium-sulfur dioxide battery system for this application was based on its high specific energy and high rate discharge capability, combined with low heat evolution, as dictated by this application. Lithium-sulfur dioxide batteries exhibit voltage delay, which tends to increase at low discharge temperatures, especially after extended storage at warm temperatures, In the absence of a depassivation circuit, as provided on earlier missions, e.g., Galileo, we were required to depassivate the lander primary batteries in a unique manner. The batteries were brought onto a shunt-regulated bus set at pre-selected discharge voltages, thus affecting depassivation during constant discharge voltages. Several ground tests were preformed, on cells, cell strings and battery assembly with five parallel strings, to identify optimum shunt voltages and durations of depassivation. We also examined the repassivation of lithium anodes, subsequent to depassivation. In this paper, we will describe these studies, in detail, as well as the depassivation of the lander flight batteries on both Spirit and Opportunity rover prior to the EDL sequence and their performance during landing on Mars.

Simulating Streamflow and Dissolved Organic Matter Export from small Forested Watersheds

NASA Astrophysics Data System (ADS)

Xu, N.; Wilson, H.; Saiers, J. E.

2010-12-01

Coupling the rainfall-runoff process and solute transport in catchment models is important for understanding the dynamics of water-quality-relevant constituents in a watershed. To simulate the hydrologic and biogeochemical processes in a parametrically parsimonious way remains challenging. The purpose of this study is to quantify the export of water and dissolved organic matter (DOM) from a forested catchment by developing and testing a coupled model for rainfall-runoff and soil-water flushing of DOM. Natural DOM plays an important role in terrestrial and aquatic systems by affecting nutrient cycling, contaminant mobility and toxicity, and drinking water quality. Stream-water discharge and DOM concentrations were measured in a first-order stream in Harvard Forest, Massachusetts. These measurements show that stream water DOM concentrations are greatest during hydrologic events induced by rainfall or snowmelt and decline to low, steady levels during periods of baseflow. Comparison of the stream-discharge data to calculations of a simple rainfall-runoff model reveals a hysteretic relationship between stream-flow rates and the storage of water within the catchment. A modified version of the rainfall-runoff model that accounts for hysteresis in the storage-discharge relationship in a parametrically simple way is capable of describing much, but not all, of the variation in the time-series data on stream discharge. Our ongoing research is aimed at linking the new rainfall-runoff formulation with coupled equations that predict soil-flushing and stream-water concentrations of DOM as functions of the temporal change in catchment water storage. This model will provide a predictive tool for examining how changes in climatic variables would affect the runoff generation and DOM fluxes from terrestrial landscape.

Team-based versus traditional primary care models and short-term outcomes after hospital discharge.

PubMed

Riverin, Bruno D; Li, Patricia; Naimi, Ashley I; Strumpf, Erin

2017-04-24

Strategies to reduce hospital readmission have been studied mainly at the local level. We assessed associations between population-wide policies supporting team-based primary care delivery models and short-term outcomes after hospital discharge. We extracted claims data on hospital admissions for any cause from 2002 to 2009 in the province of Quebec. We included older or chronically ill patients enrolled in team-based or traditional primary care practices. Outcomes were rates of readmission, emergency department visits and mortality in the 90 days following hospital discharge. We used inverse probability weighting to balance exposure groups on covariates and used marginal structural survival models to estimate rate differences and hazard ratios. We included 620 656 index admissions involving 312 377 patients. Readmission rates at any point in the 90-day post-discharge period were similar between primary care models. Patients enrolled in team-based primary care practices had lower 30-day rates of emergency department visits not associated with readmission (adjusted difference 7.5 per 1000 discharges, 95% confidence interval [CI] 4.2 to 10.8) and lower 30-day mortality (adjusted difference 3.8 deaths per 1000 discharges, 95% CI 1.7 to 5.9). The 30-day difference for mortality differed according to morbidity level (moderate morbidity: 1.0 fewer deaths per 1000 discharges in team-based practices, 95% CI 0.3 more to 2.3 fewer deaths; very high morbidity: 4.2 fewer deaths per 1000 discharges, 95% CI 3.0 to 5.3; p < 0.001). Our study showed that enrolment in the newer team-based primary care practices was associated with lower rates of postdischarge emergency department visits and death. We did not observe differences in readmission rates, which suggests that more targeted or intensive efforts may be needed to affect this outcome. © 2017 Canadian Medical Association or its licensors.

Discharge documentation of patients discharged to subacute facilities: a three-year quality improvement process across an integrated health care system.

PubMed

Gandara, Esteban; Ungar, Jonathan; Lee, Jason; Chan-Macrae, Myrna; O'Malley, Terrence; Schnipper, Jeffrey L

2010-06-01

Effective communication among physicians during hospital discharge is critical to patient care. Partners Healthcare (Boston) has been engaged in a multi-year process to measure and improve the quality of documentation of all patients discharged from its five acute care hospitals to subacute facilities. Partners first engaged stakeholders to develop a consensus set of 12 required data elements for all discharges to subacute facilities. A measurement process was established and later refined. Quality improvement interventions were then initiated to address measured deficiencies and included education of physicians and nurses, improvements in information technology, creation of or improvements in discharge documentation templates, training of hospitalists to serve as role models, feedback to physicians and their service chiefs regarding reviewed cases, and case manager review of documentation before discharge. To measure improvement in quality as a result of these efforts, rates of simultaneous inclusion of all 12 applicable data elements ("defect-free rate") were analyzed over time. Some 3,101 discharge documentation packets of patients discharged to subacute facilities from January 1, 2006, through September 2008 were retrospectively studied. During the 11 monitored quarters, the defect-free rate increased from 65% to 96% (p < .001 for trend). The largest improvements were seen in documentation of preadmission medication lists, allergies, follow-up, and warfarin information. Institution of rigorous measurement, feedback, and multidisciplinary, multimodal quality improvement processes improved the inclusion of data elements in discharge documentation required for safe hospital discharge across a large integrated health care system.

[Analysis of hydrodynamics parameters of runoff erosion and sediment-yielding on unpaved road].

PubMed

Huang, Peng-Fei; Wang, Wen-Long; Luo, Ting; Wang, Zhen; Wang, Zheng-Li; Li, Ren

2013-02-01

By the method of field runoff washout experiment, a simulation study was conducted on the relationships between the soil detachment rate and the hydrodynamic parameters on unpaved road, and the related quantitative formulas were established. Under the conditions of different flow discharges and road gradients, the averaged soil detachment rate increased with increasing flow discharge and road gradient, and the relationships between them could be described by a power function. As compared with road gradient, flow discharge had greater effects on the soil detachment rate. The soil detachment rate had a power relation with water flow velocity and runoff kinetic energy, and the runoff kinetic energy was of importance to the soil detachment rate. The soil detachment rate was linearly correlated with the unit runoff kinetic energy. The averaged soil erodibility was 0.120 g m-1.J-F-1, and the averaged critical unit runoff kinetic energy was 2.875 g.m-1.J-1. Flow discharge, road gradient, and unit runoff kinetic energy could be used to accurately describe the soil erosion process and calculate the soil erosion rate on unpaved road.

Accelerator system and method of accelerating particles

NASA Technical Reports Server (NTRS)

Wirz, Richard E. (Inventor)

2010-01-01

An accelerator system and method that utilize dust as the primary mass flux for generating thrust are provided. The accelerator system can include an accelerator capable of operating in a self-neutralizing mode and having a discharge chamber and at least one ionizer capable of charging dust particles. The system can also include a dust particle feeder that is capable of introducing the dust particles into the accelerator. By applying a pulsed positive and negative charge voltage to the accelerator, the charged dust particles can be accelerated thereby generating thrust and neutralizing the accelerator system.

Self-teaching digital-computer program for fail-operational control of a turbojet engine in a sea-level test stand

NASA Technical Reports Server (NTRS)

Wallhagen, R. E.; Arpasi, D. J.

1974-01-01

The design and evaluation are described of a digital turbojet engine control which is capable of sensing catastrophic failures in either the engine rotor speed or the compressor discharge static-pressure signal and is capable of switching control modes to maintain near normal operation. The control program was developed for and tested on a turbojet engine located in a sea-level test stand. The control program is also capable of acquiring all the data that are necessary for the fail-operational control to function.

Readmission Patterns Over 90-Day Episodes of Care Among Medicare Fee-for-Service Beneficiaries Discharged to Post-acute Care.

PubMed

Middleton, Addie; Kuo, Yong-Fang; Graham, James E; Karmarkar, Amol; Lin, Yu-Li; Goodwin, James S; Haas, Allen; Ottenbacher, Kenneth J

2018-04-21

Examine readmission patterns over 90-day episodes of care in persons discharged from hospitals to post-acute settings. Retrospective cohort study. Acute care hospitals. Medicare fee-for-service enrollees (N = 686,877) discharged from hospitals to post-acute care in 2013-2014. The cohort included beneficiaries >65 years of age hospitalized for stroke, joint replacement, or hip fracture and who survived for 90 days following discharge. 90-day unplanned readmissions. The cohort included 127,680 individuals with stroke, 442,195 undergoing joint replacement, and 117,002 with hip fracture. Thirty-day readmission rates ranged from 3.1% for knee replacement patients discharged to home health agencies (HHAs) to 14.4% for hemorrhagic stroke patients discharged to skilled nursing facilities (SNFs). Ninety-day readmission rates ranged from 5.0% for knee replacement patients discharged to HHAs to 26.1% for hemorrhagic stroke patients discharged to SNFs. Differences in readmission rates decreased between stroke subconditions (hemorrhagic and ischemic) and increased between joint replacement subconditions (knee, elective hip, and nonelective hip) from 30 to 90 days across all initial post-acute discharge settings. We observed clear patterns in readmissions over 90-day episodes of care across post-acute discharge settings and subconditions. Our findings suggest that patients with hemorrhagic stroke may be more vulnerable than those with ischemic over the first 30 days after hospital discharge. For patients receiving nonelective joint replacements, readmission prevention efforts should start immediately after discharge and continue, or even increase, over the 90-day episode of care. Copyright © 2018 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.

Outcomes of Fort Jackson's Physical Training and Rehabilitation Program in army basic combat training: return to training, graduation, and 2-year retention.

PubMed

Hauret, Keith G; Knapik, Joseph J; Lange, Jeffrey L; Heckel, Heidi A; Coval, Dana L; Duplessis, David H

2004-07-01

Basic trainees at Fort Jackson, South Carolina, who were unable to continue basic combat training (BCT) because of a serious injury were assigned to the Physical Training and Rehabilitation Program (PTRP). Between January 3, 1998 and July 24, 2001, 4258 trainees were assigned to the PTRP. Using a retrospective cohort study design, return to training and BCT graduation rates were evaluated. PTRP graduates were compared with matched non-PTRP graduates for 2-year retention in the Army. More PTRP women than men were discharged from the PTRP (60% and 48%, respectively, p < 0.01). Of PTRP trainees returning to BCT, 10% and 12% of men and women, respectively, were discharged from the Army compared with overall Fort Jackson discharge rates of 9% and 15% for men and women, respectively. Comparing PTRP graduates to matched non-PTRP graduates, there were no differences in 2-year retention for men (14.9% and 14.7%, respectively; p = 0.93) or women (26.6% and 30.1%, respectively; p = 0.19). Despite the high discharge rate in the PTRP, the BCT discharge rate for trainees who successfully rehabilitated was similar to the overall discharge rate at Fort Jackson. The 2-year retention in service for PTRP trainees who graduated from BCT was similar to that of non-PTRP trainees.

Effect of turbulent flow on an atmospheric-pressure AC powered gliding arc discharge

NASA Astrophysics Data System (ADS)

Kong, Chengdong; Gao, Jinlong; Zhu, Jiajian; Ehn, Andreas; Aldén, Marcus; Li, Zhongshan

2018-06-01

A high-power gliding arc (GA) discharge was generated in a turbulent air flow driven by a 35 kHz alternating current electric power supply. The effects of the flow rate on the characteristics of the GA discharge were investigated using combined optical and electrical diagnostics. Phenomenologically, the GA discharge exhibits two types of discharge, i.e., glow type and spark type, depending on the flow rates and input powers. The glow-type discharge, which has peak currents of hundreds of milliamperes, is sustained at low flow rates. The spark-type discharge, which is characterized by a sharp current spike of several amperes with duration of less than 1 μs, occurs more frequently as the flow rate increases. Higher input power can suppress spark-type discharges in moderate turbulence, but this effect becomes weak under high turbulent conditions. Physically, the transition between glow- and spark-type is initiated by the short cutting events and the local re-ignition events. Short cutting events occur owing to the twisting, wrinkling, and stretching of the plasma columns that are governed by the relatively large vortexes in the flow. Local re-ignition events, which are defined as re-ignition along plasma columns, are detected in strong turbulence due to increment of the impedance of the plasma column and consequently the internal electric field strength. It is suggested that the vortexes with length scales smaller than the size of the plasma can penetrate into the plasma column and promote mixing with surroundings to accelerate the energy dissipation. Therefore, the turbulent flow influences the GA discharges by ruling the short cutting events with relatively large vortexes and the local re-ignition events with small vortexes.

River mouth morphodynamics - Examples from small, mountainous rivers (Invited)

NASA Astrophysics Data System (ADS)

Warrick, J. A.

2013-12-01

Small, high-sediment yield rivers are known to discharge massive amounts of sediment to the world's oceans. Because of these high rates of sediment discharge, many of these small rivers provide important sources of sediment to littoral cells, such as those along the west coasts of North and South America. Sediment discharge from these small watersheds is commonly ephemeral and dominated by infrequent high flow. Thus, the morphodynamic states of these river mouths will vary with time, often being 'wave dominated' for the majority of the year and then changing to 'river dominated' during river sediment discharge events. Here I will provide a summary of recent observations of the morphodynamics of river mouths along California that reveal that sediment dispersal and deposition patterns vary owing to the sediment transport processes at the river mouths, which are influenced by the buoyancy of the river discharge. During low rates of sediment discharge and low river sediment concentrations, sediment dispersal will occur in hypopycnal (positively buoyant) plumes and sand deposition will be close to the river mouth. These conditions commonly result in transfer of sand from the river delta to the littoral cell during the first 1-2 years following the river discharge event. During high rates of sediment discharge and high river sediment concentrations, river discharge may form hyperpycnal (negatively buoyant) plumes and disperse sand to deeper portions of the continental shelf, where transfer back to the littoral cell may take decades or may not occur. High-resolution bathymetry from southern California provides several examples of sand dispersal by hyperpycnal plumes to regions of the inner and middle continental shelf. Thus, sediment dispersal from river mouths influences coastal morphodynamics, morphology, and the rates and timing of sediment supply to littoral cells.

Calculating mercury loading to the tidal Hudson River, New York, using rating curve and surrogate methodologies

USGS Publications Warehouse

Wall, G.R.; Ingleston, H.H.; Litten, S.

2005-01-01

Total mercury (THg) load in rivers is often calculated from a site-specific "rating-curve" based on the relation between THg concentration and river discharge along with a continuous record of river discharge. However, there is no physical explanation as to why river discharge should consistently predict THg or any other suspended analyte. THg loads calculated by the rating-curve method were compared with those calculated by a "continuous surrogate concentration" (CSC) method in which a relation between THg concentration and suspended-sediment concentration (SSC) is constructed; THg loads then can be calculated from the continuous record of SSC and river discharge. The rating-curve and CSC methods, respectively, indicated annual THg loads of 46.4 and 75.1 kg for the Mohawk River, and 52.9 and 33.1 kg for the upper Hudson River. Differences between the results of the two methods are attributed to the inability of the rating-curve method to adequately characterize atypical high flows such as an ice-dam release, or to account for hysteresis, which typically degrades the strength of the relation between stream discharge and concentration of material in suspension. ?? Springer 2005.

Impact of tailored falls prevention education for older adults at hospital discharge on engagement in falls prevention strategies postdischarge: protocol for a process evaluation.

PubMed

Naseri, Chiara; McPhail, Steven M; Netto, Julie; Haines, Terrence P; Morris, Meg E; Etherton-Beer, Christopher; Flicker, Leon; Lee, Den-Ching A; Francis-Coad, Jacqueline; Hill, Anne-Marie

2018-04-20

Older adults recently discharged from hospital have greater incidence of adverse events, functional decline, falls and subsequent readmission. Providing education to hospitalised patients on how to prevent falls at home could reduce postdischarge falls. There has been limited research investigating how older adults respond to tailored falls prevention education provided at hospital discharge. The aim of this study is to evaluate how providing tailored falls prevention education to older patients at the point of, and immediately after hospital discharge in addition to usual care, affects engagement in falls prevention strategies in the 6-months postdischarge period, including their capability and motivation to engage in falls prevention strategies. This prospective observational cohort study is a process evaluation of a randomised controlled trial, using an embedded mixed-method design. Participants (n=390) who have been enrolled in the trial are over the age of 60 years, scoring greater than 7/10 on the Abbreviated Mental Test Score. Participants are being discharged from hospital rehabilitation wards in Perth, Western Australia, and followed up for 6 months postdischarge. Primary outcome measures for the process evaluation are engagement in falls prevention strategies, including exercise, home modifications and receiving assistance with activities of daily living. Secondary outcomes will measure capability, motivation and opportunity to engage in falls prevention strategies, based on the constructs of the Capability Opportunity Motivation Behaviour system. Quantitative data are collected at baseline, then at 6 months postdischarge using structured phone interviews. Qualitative data are collected from a purposive sample of the cohort, using semistructured in-depth phone interviews. Quantitative data will be analysed using regression modelling and qualitative data will be analysed using interpretive phenomenological analysis. Results will be presented in peer-reviewed journals and at conferences worldwide. This study is approved by hospital and university Human Research Ethics Committees. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

A method for extending stage-discharge relationships using a hydrodynamic model and quantifying the associated uncertainty

NASA Astrophysics Data System (ADS)

Shao, Quanxi; Dutta, Dushmanta; Karim, Fazlul; Petheram, Cuan

2018-01-01

Streamflow discharge is a fundamental dataset required to effectively manage water and land resources. However, developing robust stage - discharge relationships called rating curves, from which streamflow discharge is derived, is time consuming and costly, particularly in remote areas and especially at high stage levels. As a result stage - discharge relationships are often heavily extrapolated. Hydrodynamic (HD) models are physically based models used to simulate the flow of water along river channels and over adjacent floodplains. In this paper we demonstrate a method by which a HD model can be used to generate a 'synthetic' stage - discharge relationship at high stages. The method uses a both-side Box-Cox transformation to calibrate the synthetic rating curve such that the regression residuals are as close to the normal distribution as possible. By doing this both-side transformation, the statistical uncertainty in the synthetically derived stage - discharge relationship can be calculated. This enables people trying to make decisions to determine whether the uncertainty in the synthetically generated rating curve at high stage levels is acceptable for their decision. The proposed method is demonstrated in two streamflow gauging stations in north Queensland, Australia.

Study of a plate-electrode XeCl laser with a pulse repetition rate up to 5 kHz

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

Voevodin, Denis D; Vysotskii, Andrei V; Lazhintsev, Boris V

2012-11-30

The results of the study of a repetitively pulsed XeCl laser with a high rate of pulse repetition and the electrode assembly based on a multi-section discharge gap with inductance-capacitance stabilisation of the discharge are presented. The multi-section discharge gap is formed by 25 pairs of anode - cathode plates. The discharge formed in the interelectrode gap had the dimensions 250 Multiplication-Sign 12 Multiplication-Sign 2 mm. The studies were performed using the HCl - Xe - Ne laser mixture at the total pressure up to 3.5 atm. The limit value of the radiation pulse repetition rate was equal to 5more » kHz. The meansquare deviation of the pulse energy increased from 0.8 % to 1.6 % in the range of repetition rates from 1 to 4.5 kHz and did not exceed 2.4 % at the frequency 5 kHz. The maximal energy of the laser pulse and the efficiency coefficient were equal to 7.9 mJ and 1.6 %, respectively. The maximal power of laser radiation (31 W) was obtained at the repetition rate 5 kHz. A new technique of measuring the gas flow velocity in the interelectrode gap is proposed. The velocity of gas circulation at the maximal pressure of the mixture did not exceed 18 m s{sup -1}. Optical inhomogeneities were observed, caused by a high concentration of electrons in the discharge plasma, by the acoustic wave, arising in the discharge gap, and by the heating of the gas in the discharge. (lasers)« less

PFAM 2.0 - Documentations

EPA Pesticide Factsheets

The advanced capabilities of PFAM include accounting for water and pest management practices and for degradation in soil and aquatic environments, as well as for post processing of discharged paddy waters to a user-defined receiving water.

Association of Discharge Home with Home Health Care and 30-day Readmission after Pancreatectomy

PubMed Central

Sanford, Dominic E; Olsen, Margaret A; Bommarito, Kerry M; Shah, Manish; Fields, Ryan C; Hawkins, William G; Jaques, David P; Linehan, David C

2014-01-01

Background We sought to determine if discharge home with home health care (HHC) is an independent predictor of increased readmission following pancreatectomy. Study Design We examined 30-day readmissions in patients undergoing pancreatectomy using the Healthcare Cost and Utilization Project State Inpatient Database for California from 2009 to 2011. Readmissions were categorized as severe or non-severe using the Modified Accordion Severity Grading System. Multivariable logistic regression models were used to examine the association of discharge home with HHC and 30-day readmission using discharge home without HHC as the reference group. Propensity score matching was used as an additional analysis to compare the rate of 30-day readmission between patients discharged home with HHC to patients discharged home without HHC. Results 3,573 patients underwent pancreatectomy and 752 (21.0%) were readmitted within 30 days of discharge. In a multivariable logistic regression model, discharge home with HHC was an independent predictor of increased 30-day readmission (OR=1.37; 95%CI=1.11-1.69, p=0.004). Using propensity score matching, patients who received HHC had a significantly increased rate of 30-day readmission compared to patients discharged home without HHC (24.3% vs 19.8%, p<0.001). Patients discharged home with HHC had a significantly increased rate of non-severe readmission compared to those discharged home without HHC by univariate comparison (19.2% vs 13.9%, p<0.001), but not severe readmission (6.4% vs 4.7%, p= 0.08). In multivariable logistic regression models, excluding patients discharged to facilities, discharge home with HHC was an independent predictor of increased non-severe readmissions (OR=1.41; 95%CI=1.11-1.79, p=0.005), but not severe readmissions (OR=1.31; 95%CI=0.88-1.93, p=0.18). Conclusions Discharge home with HHC following pancreatectomy is an independent predictor of increased 30-day readmission; specifically, these services are associated with increased non-severe readmissions, but not severe readmissions. PMID:25440026

Stage-discharge rating curves based on satellite altimetry and modeled discharge in the Amazon basin

NASA Astrophysics Data System (ADS)

Paris, Adrien; Dias de Paiva, Rodrigo; Santos da Silva, Joecila; Medeiros Moreira, Daniel; Calmant, Stephane; Garambois, Pierre-André; Collischonn, Walter; Bonnet, Marie-Paule; Seyler, Frederique

2016-05-01

In this study, rating curves (RCs) were determined by applying satellite altimetry to a poorly gauged basin. This study demonstrates the synergistic application of remote sensing and watershed modeling to capture the dynamics and quantity of flow in the Amazon River Basin, respectively. Three major advancements for estimating basin-scale patterns in river discharge are described. The first advancement is the preservation of the hydrological meanings of the parameters expressed by Manning's equation to obtain a data set containing the elevations of the river beds throughout the basin. The second advancement is the provision of parameter uncertainties and, therefore, the uncertainties in the rated discharge. The third advancement concerns estimating the discharge while considering backwater effects. We analyzed the Amazon Basin using nearly one thousand series that were obtained from ENVISAT and Jason-2 altimetry for more than 100 tributaries. Discharge values and related uncertainties were obtained from the rain-discharge MGB-IPH model. We used a global optimization algorithm based on the Monte Carlo Markov Chain and Bayesian framework to determine the rating curves. The data were randomly allocated into 80% calibration and 20% validation subsets. A comparison with the validation samples produced a Nash-Sutcliffe efficiency (Ens) of 0.68. When the MGB discharge uncertainties were less than 5%, the Ens value increased to 0.81 (mean). A comparison with the in situ discharge resulted in an Ens value of 0.71 for the validation samples (and 0.77 for calibration). The Ens values at the mouths of the rivers that experienced backwater effects significantly improved when the mean monthly slope was included in the RC. Our RCs were not mission-dependent, and the Ens value was preserved when applying ENVISAT rating curves to Jason-2 altimetry at crossovers. The cease-to-flow parameter of our RCs provided a good proxy for determining river bed elevation. This proxy was validated against Acoustic Doppler current profiler (ADCP) cross sections with an accuracy of more than 90%. Altimetry measurements are routinely delivered within a few days, and this RC data set provides a simple and cost-effective tool for predicting discharge throughout the basin in nearly real time.

Suicide Rates After Discharge From Psychiatric Facilities: A Systematic Review and Meta-analysis.

PubMed

Chung, Daniel Thomas; Ryan, Christopher James; Hadzi-Pavlovic, Dusan; Singh, Swaran Preet; Stanton, Clive; Large, Matthew Michael

2017-07-01

High rates of suicide after psychiatric hospitalization are reported in many studies, yet the magnitude of the increases and the factors underlying them remain unclear. To quantify the rates of suicide after discharge from psychiatric facilities and examine what moderates those rates. English-language, peer-reviewed publications published from January 1, 1946, to May 1, 2016, were located using MEDLINE, PsychINFO, and EMBASE with the search terms ((suicid*).ti AND (hospital or discharg* OR inpatient or in-patient OR admit*).ab and ((mortality OR outcome* OR death*) AND (psych* OR mental*)).ti AND (admit* OR admis* or hospital* OR inpatient* OR in-patient* OR discharg*).ab. Hand searching was also done. Studies reporting the number of suicides among patients discharged from psychiatric facilities and the number of exposed person-years and studies from which these data could be calculated. The meta-analysis adhered to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines. A random-effects model was used to calculate a pooled estimate of postdischarge suicides per 100 000 person-years. The suicide rate after discharge from psychiatric facilities was the main outcome, and the association between the duration of follow-up and the year of the sampling were the main a priori moderators. A total of 100 studies reported 183 patient samples (50 samples of females, 49 of males, and 84 of mixed sex; 129 of adults or unspecified patients, 20 of adolescents, 19 of older patients, and 15 from long-term or forensic discharge facilities), including a total of 17 857 suicides during 4 725 445 person-years. The pooled estimate postdischarge suicide rate was 484 suicides per 100 000 person-years (95% CI, 422-555 suicides per 100 000 person-years; prediction interval, 89-2641), with high between-sample heterogeneity (I2 = 98%). The suicide rate was highest within 3 months after discharge (1132; 95% CI, 874-1467) and among patients admitted with suicidal ideas or behaviors (2078; 95% CI, 1512-2856). Pooled suicide rates per 100 000 patients-years were 654 for studies with follow-up periods of 3 months to 1 year, 494 for studies with follow-up periods of 1 to 5 years, 366 for studies with follow-up periods of 5 to 10 years, and 277 for studies with follow-up periods longer than 10 years. Suicide rates were higher among samples collected in the periods 1995-2004 (656; 95% CI, 518-831) and 2005-2016 (672; 95% CI, 428-1055) than in earlier samples. The immediate postdischarge period is a time of marked risk, but rates of suicide remain high for many years after discharge. Patients admitted because of suicidal ideas or behaviors and those in the first months after discharge should be a particular focus of concern. Previously admitted patients should be able to access long-term care and assistance.

Impact of comprehensive insurance parity on follow-up care after psychiatric inpatient treatment in Oregon.

PubMed

Wallace, Neal T; McConnell, K John

2013-10-01

This study assessed the impact of Oregon's 2007 parity law, which required behavioral health insurance parity, on rates of follow-up care provided within 30 days of psychiatric inpatient care. Data sources were claims (2005-2008) for 737 individuals with inpatient stays for a mental disorder who were continuously enrolled in insurance plans affected by the parity law (intervention group) or in commercial, self-insured plans that were not affected by the law (control group). A difference-in-difference analysis was used to compare rates of follow-up care before and after the parity law between discharges of individuals in the intervention group and the control group and between discharges of individuals in the intervention group who had or had not met preparity quantitative coverage limits during a coverage year. Estimates of the marginal effects of the parity law were adjusted for gender, discharge diagnosis, relationship to policy holder, and calendar quarter of discharge. The study included 353 discharges in the intervention group and 535 discharges in the control group. After the parity law, follow-up rates increased by 11% (p=.042) overall and by 20% for discharges of individuals who had met coverage limits (p=.028). The Oregon parity law was associated with a large increase in the rate of follow-up care, predominantly for discharges of individuals who had met preparity quantitative coverage limits. Given similarities between the law and the 2008 Mental Health Parity and Addiction Equity Act, the results may portend a national effect of more comprehensive parity laws.

Feasibility of a Clinical Pathway with Early Oral Intake and Discharge for Laparoscopic Gastrectomy.

PubMed

Nakagawa, M; Tomii, C; Inokuchi, M; Otsuki, S; Kojima, K

2017-12-01

Although some studies have reported the safety of early oral intake after gastrectomy, it still remains controversial. This study focused on the feasibility of a clinical pathway with early oral intake and discharge setting for exclusively laparoscopic distal gastrectomy. A clinical pathway was applied to 403 patients until December 2014. In the protocol, patients are allowed to take a sip of water and a soft diet on the first and second days after the operation, respectively, and the discharge day is set as the fifth to seventh day after the operation. Clinicopathological variables were prospectively collected, and risk factors for discharge variances were analyzed. The completion rate of the clinical pathway was 76.9%. There were five re-admissions (1.2%). The overall morbidity rate was 18% ( n = 72), and major complications (Clavien-Dindo IIIa or greater) occurred in 13 patients (3%). Complications were the causes for discharge variances in 68 cases (73%), while the attending surgeons' judgment was the cause in 25 cases (27%). On multivariate analysis, age (odds ratio = 2.23, 95% confidence interval = 1.38-3.60, p = 0.001) and operative time (odds ratio = 2.38, 95% confidence interval = 1.45-3.98, p = 0.001) were independent risk factors for discharge variances. A high completion rate of a clinical pathway with early oral intake and discharge setting for laparoscopic distal gastrectomy was achievable with an acceptably low re-admission rate. Laparoscopic distal gastrectomy is recommended as a first step for a clinical pathway with an early oral intake and discharge protocol.

Uncertainty estimation with bias-correction for flow series based on rating curve

NASA Astrophysics Data System (ADS)

Shao, Quanxi; Lerat, Julien; Podger, Geoff; Dutta, Dushmanta

2014-03-01

Streamflow discharge constitutes one of the fundamental data required to perform water balance studies and develop hydrological models. A rating curve, designed based on a series of concurrent stage and discharge measurements at a gauging location, provides a way to generate complete discharge time series with a reasonable quality if sufficient measurement points are available. However, the associated uncertainty is frequently not available even though it has a significant impact on hydrological modelling. In this paper, we identify the discrepancy of the hydrographers' rating curves used to derive the historical discharge data series and proposed a modification by bias correction which is also in the form of power function as the traditional rating curve. In order to obtain the uncertainty estimation, we propose a further both-side Box-Cox transformation to stabilize the regression residuals as close to the normal distribution as possible, so that a proper uncertainty can be attached for the whole discharge series in the ensemble generation. We demonstrate the proposed method by applying it to the gauging stations in the Flinders and Gilbert rivers in north-west Queensland, Australia.

Breakdown characteristics of atmospheric dielectric barrier discharge in gas flow condition

NASA Astrophysics Data System (ADS)

Fan, Zhihui; Yan, Huijie; Wang, Yuying; Liu, Yidi; Guo, Hongfei; Ren, Chunsheng

2018-05-01

Experimental investigations of the breakdown characteristics of plate-to-plate dielectric barrier discharge excited by an AC source at different gas flow conditions are carried out. The ignition voltage for the appearance of the very first discharge filament and the breakdown voltage in each discharge half cycle in continuous operation are examined. As revealed by the results of the indoor air experiment, the ignition voltage manifests a monotonous increase with the increase in the gas flow rate, while the breakdown voltage has a marked decline at the low gas flow rate and increases slightly as the gas flow rate is higher than 10 m/s. As regards the obvious decreases in the ignition voltage and breakdown voltage, the decrease in the humidity with the increase in the gas flow rate plays a dominant role. As regards the increase in breakdown voltage, the memory effect from the preceding discharge is considered. The losses of metastable particles, together with particles having high translational energy in the gas flow, are considered to be the most critical factors.

Effect of transition metal composition on electrochemical performance of nickel-manganese-based lithium-rich layer-structured cathode materials in lithium-ion batteries

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

Konishi, Hiroaki, E-mail: hiroaki.konishi.yj@hitachi.com; Gunji, Akira; Feng, Xiaoliang

2017-05-15

To evaluate the effect of transition metal composition on the electrochemical properties of Li-rich layer-structured cathode materials, Li{sub 1.2}Ni{sub x}Mn{sub 0.8−x}O{sub 2} (x=0.2, 0.25, 0.3, and 0.4) were synthesized, and their electrochemical properties were investigated. As nickel content x increased in Li{sub 1.2}Ni{sub x}Mn{sub 0.8−x}O{sub 2} (x=0.2, 0.25, 0.3, and 0.4), charge-discharge capacities at a low C-rate (0.05 C) decreased. The results obtained by dQ/dV curves indicate that, as the nickel content increased, the discharge capacity below 3.6 V greatly decreased, but that above 3.6 V increased. As the C-rate of the discharge process increased, the discharge reaction of Li{submore » 1.2}Ni{sub x}Mn{sub 0.8−x}O{sub 2} (x=0.2) below 3.6 V greatly decreased. In contrast, that above 3.6 V slightly decreased. This indicates that the discharge reaction above 3.6 V exhibits higher rate performance than that below 3.6 V. For the high-nickel-content cathodes, the ratio of the discharge capacity above 3.6 V to the total discharge capacity was high. Therefore, they exhibited high rate performance. - Graphical abstract: Figure shows the discharge curves of Li{sub 1.2}Ni{sub x}Mn{sub 0.8−x}O{sub 2} (x=0.2 and 0.3) within potential range of 2.5−4.6 V (vs. Li/Li{sup +}) at 0.05 and 3 C. At low C-rate (0.05 C), the discharge capacity of high-nickel-content cathode (Li{sub 1.2}Ni{sub 0.3}Mn{sub 0.5}O{sub 2}) was less than that of low-nickel-content cathode (Li{sub 1.2}Ni{sub 0.2}Mn{sub 0.6}O{sub 2}); however, the discharge potential and capacity of Li{sub 1.2}Ni{sub 0.3}Mn{sub 0.5}O{sub 2} was higher than those of Li{sub 1.2}Ni{sub 0.2}Mn{sub 0.6}O{sub 2} at high C-rate (3 C). This means that the increase in Ni/Mn ratio was effective in improving rate-performance.« less

Home health agency work environments and hospitalizations.

PubMed

Jarrín, Olga; Flynn, Linda; Lake, Eileen T; Aiken, Linda H

2014-10-01

An important goal of home health care is to assist patients to remain in community living arrangements. Yet home care often fails to prevent hospitalizations and to facilitate discharges to community living, thus putting patients at risk of additional health challenges and increasing care costs. To determine the relationship between home health agency work environments and agency-level rates of acute hospitalization and discharges to community living. Analysis of linked Center for Medicare and Medicaid Services Home Health Compare data and nurse survey data from 118 home health agencies. Robust regression models were used to estimate the effect of work environment ratings on between-agency variation in rates of acute hospitalization and community discharge. Home health agencies with good work environments had lower rates of acute hospitalizations and higher rates of patient discharges to community living arrangements compared with home health agencies with poor work environments. Improved work environments in home health agencies hold promise for optimizing patient outcomes and reducing use of expensive hospital and institutional care.

Lithium thionyl chloride high rate discharge

NASA Technical Reports Server (NTRS)

Klinedinst, K. A.

1980-01-01

Improvements in high rate lithium thionyl chloride power technology achieved by varying the electrolyte composition, operating temperature, cathode design, and cathode composition are discussed. Discharge capacities are plotted as a function of current density, cell voltage, and temperature.

Sediment and water discharge rates of Turkish Black Sea rivers before and after hydropower dam construction

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

Hay, B.J.

1994-06-01

Presently, the water discharge rate to the Black Sea by Turkish rivers is approximately 41 km[sup 3]/yr. The sediment discharge rate of Turkish rivers to the Black Sea is 28 x 10[sup 6] t/yr. Before construction of the hydroelectric dams, the sediment discharge rate was approximately 70 x 10[sup 6] t/yr. The sharp reduction in sediment load is largely a result of the dams near the mouths of the Yesil Irmak and Kizil Irmak rivers. Before the construction of dams, Turkish rivers contributed approximately one third of the total amount of sediment received by the Black Sea from all surroundingmore » rivers. The life-span of the major reservoirs varies from approximately only one century (Yesil Irmak river reservoirs) to several thousand years (Sakarya river reservoirs). Life-span for the large Altinkaya Dam reservoir is estimated with approximately 500 yr.« less

Volcano seismicity and ground deformation unveil the gravity-driven magma discharge dynamics of a volcanic eruption.

PubMed

Ripepe, Maurizio; Donne, Dario Delle; Genco, Riccardo; Maggio, Giuseppe; Pistolesi, Marco; Marchetti, Emanuele; Lacanna, Giorgio; Ulivieri, Giacomo; Poggi, Pasquale

2015-05-18

Effusive eruptions are explained as the mechanism by which volcanoes restore the equilibrium perturbed by magma rising in a chamber deep in the crust. Seismic, ground deformation and topographic measurements are compared with effusion rate during the 2007 Stromboli eruption, drawing an eruptive scenario that shifts our attention from the interior of the crust to the surface. The eruption is modelled as a gravity-driven drainage of magma stored in the volcanic edifice with a minor contribution of magma supplied at a steady rate from a deep reservoir. Here we show that the discharge rate can be predicted by the contraction of the volcano edifice and that the very-long-period seismicity migrates downwards, tracking the residual volume of magma in the shallow reservoir. Gravity-driven magma discharge dynamics explain the initially high discharge rates observed during eruptive crises and greatly influence our ability to predict the evolution of effusive eruptions.

In Situ Chelating Synthesis of Hierarchical LiNi1/3 Co1/3 Mn1/3 O2 Polyhedron Assemblies with Ultralong Cycle Life for Li-Ion Batteries.

PubMed

Zhang, Yue; Jia, Dianzeng; Tang, Yakun; Huang, Yudai; Pang, Weikong; Guo, Zaiping; Zhou, Zhen

2018-06-03

Layered lithium transition-metal oxides, with large capacity and high discharge platform, are promising cathode materials for Li-ion batteries. However, their high-rate cycling stability still remains a large challenge. Herein, hierarchical LiNi 1/3 Co 1/3 Mn 1/3 O 2 polyhedron assemblies are obtained through in situ chelation of transition metal ions (Ni 2+ , Co 2+ , and Mn 2+ ) with amide groups uniformly distributed along the backbone of modified polyacrylonitrile chains to achieve intimate mixing at the atomic level. The assemblies exhibit outstanding electrochemical performances: superior rate capability, high volumetric energy density, and especially ultralong high-rate cyclability, due to the superiority of unique hierarchical structures. The polyhedrons with exposed active crystal facets provide more channels for Li + diffusion, and meso/macropores serve as access shortcuts for fast migration of electrolytes, Li + and electrons. The strategy proposed in this work can be extended to fabricate other mixed transition metal-based materials for advanced batteries. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An ultrafast rechargeable aluminium-ion battery.

PubMed

Lin, Meng-Chang; Gong, Ming; Lu, Bingan; Wu, Yingpeng; Wang, Di-Yan; Guan, Mingyun; Angell, Michael; Chen, Changxin; Yang, Jiang; Hwang, Bing-Joe; Dai, Hongjie

2015-04-16

The development of new rechargeable battery systems could fuel various energy applications, from personal electronics to grid storage. Rechargeable aluminium-based batteries offer the possibilities of low cost and low flammability, together with three-electron-redox properties leading to high capacity. However, research efforts over the past 30 years have encountered numerous problems, such as cathode material disintegration, low cell discharge voltage (about 0.55 volts; ref. 5), capacitive behaviour without discharge voltage plateaus (1.1-0.2 volts or 1.8-0.8 volts) and insufficient cycle life (less than 100 cycles) with rapid capacity decay (by 26-85 per cent over 100 cycles). Here we present a rechargeable aluminium battery with high-rate capability that uses an aluminium metal anode and a three-dimensional graphitic-foam cathode. The battery operates through the electrochemical deposition and dissolution of aluminium at the anode, and intercalation/de-intercalation of chloroaluminate anions in the graphite, using a non-flammable ionic liquid electrolyte. The cell exhibits well-defined discharge voltage plateaus near 2 volts, a specific capacity of about 70 mA h g(-1) and a Coulombic efficiency of approximately 98 per cent. The cathode was found to enable fast anion diffusion and intercalation, affording charging times of around one minute with a current density of ~4,000 mA g(-1) (equivalent to ~3,000 W kg(-1)), and to withstand more than 7,500 cycles without capacity decay.

A combined theoretical and experimental study on the oxygenated graphitic carbon nitride as a promising sulfur host for lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

He, Feng; Li, Kai; Yin, Cong; Ding, Yingchun; Tang, Hao; Wang, Ying; Wu, Zhijian

2018-01-01

To effectively restrain the dissolution of soluble polysulfides and fully utilize the active sulfur materials in lithium-sulfur (Li-S) batteries, host materials with unique compositions and porous structures have been pursued. Herein, we have investigated the mechanism of the excellent activity of oxygenated g-C3N4 for Li-S batteries from theoretical perspective, and the further experiment confirms that our O-g-C3N4-S cathode exhibits much better electrochemical performance compared with those in previous reports. Our DFT calculations reveal that the oxygenated material has better electrical conductivity and stronger adsorption ability with the Li2Sx species compared with the pristine g-C3N4 and other two-dimensional (2D) materials. Furthermore, we have confirmed experimentally that the O-g-C3N4-S composite cathode exhibits excellent electrochemical performance in Li-S batteries with high reversible discharge capacity of 1030 mAh g-1 after 100 cycles at 0.2 C, great rate capability with the discharge capacity of 364 mAh g-1 even at 5.0 C, and outstanding long-term cyclic stability with the discharge capacity of 465 mAh g-1 after 1000 cycles at 1.0 C (capacity decay was only 0.046% per cycle). Our results also suggest that theoretical study will play a significant role in predicting and screening novel materials with better performance.

Merging Infrasound and Electromagnetic Signals as a Means for Nuclear Explosion Detection

NASA Astrophysics Data System (ADS)

Ashkenazy, Joseph; Lipshtat, Azi; Kesar, Amit S.; Pistinner, Shlomo; Ben Horin, Yochai

2016-04-01

The infrasound monitoring network of the CTBT consists of 60 stations. These stations are capable of detecting atmospheric events, and may provide approximate location within time scale of a few hours. However, the nature of these events cannot be deduced from the infrasound signal. More than two decades ago it was proposed to use the electromagnetic pulse (EMP) as a means of discriminating nuclear explosion from other atmospheric events. An EMP is a unique signature of nuclear explosion and is not detected from chemical ones. Nevertheless, it was decided to exclude the EMP technology from the official CTBT verification regime, mainly because of the risk of high false alarm rate, due to lightning electromagnetic pulses [1]. Here we present a method of integrating the information retrieved from the infrasound system with the EMP signal which enables us to discriminate between lightning discharges and nuclear explosions. Furthermore, we show how spectral and other characteristics of the electromagnetic signal emitted from a nuclear explosion are distinguished from those of lightning discharge. We estimate the false alarm probability of detecting a lightning discharge from a given area of the infrasound event, and identifying it as a signature of a nuclear explosion. We show that this probability is very low and conclude that the combination of infrasound monitoring and EMP spectral analysis may produce a reliable method for identifying nuclear explosions. [1] R. Johnson, Unfinished Business: The Negotiation of the CTBT and the End of Nuclear Testing, United Nations Institute for Disarmament Research, 2009.

Three-dimensional ordered macroporous MnO2/carbon nanocomposites as high-performance electrodes for asymmetric supercapacitors.

PubMed

Yang, Chunzhen; Zhou, Ming; Xu, Qian

2013-12-07

MnO2/carbon composites with ultrathin MnO2 nanofibers (diameter of 5-10 nm) uniformly deposited on three dimensional ordered macroporous (3DOM) carbon frameworks were fabricated via a self-limiting redox process. The MnO2 nanofibers provide a large surface area for charge storage, whereas the 3DOM carbon serves as a desirable supporting material providing rapid ion and electron transport through the composite electrodes. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) were used to characterize the capacitive performance of these composites. Optimization of the composition results in a composite with 57 wt% MnO2 content, which gives both a high specific capacitance (234 F g(-1) at a discharge current of 0.1 A g(-1)) and good rate capability (52% retention of the capacitance at 5 A g(-1)). An asymmetric supercapacitor was fabricated by assembling the optimized MnO2/carbon composite as the positive electrode and 3DOM carbon as the negative electrode. The asymmetric supercapacitor exhibits superior electrochemical performances, which can be reversibly charged and discharged at a maximum cell voltage of 2.0 V in 1.0 M Na2SO4 aqueous electrolyte, delivering both high energy density (30.2 W h kg(-1)) and power density (14.5 kW kg(-1)). Additionally, the asymmetric supercapacitor exhibits an excellent cycle life, with 95% capacitance retained after 1000 cycles.

Synthesis of a highly efficient 3D graphene-CNT-MnO2-PANI nanocomposite as a binder free electrode material for supercapacitors.

PubMed

Asif, Muhammad; Tan, Yi; Pan, Lujun; Rashad, Muhammad; Li, Jiayan; Fu, Xin; Cui, Ruixue

2016-09-29

Graphene based nanocomposites have been investigated intensively, as electrode materials for energy storage applications. In the current work, a graphene-CNT-MnO 2 -PANI (GCM@PANI) nanocomposite has been synthesized on 3D graphene grown on nickel foam, as a highly efficient binder free electrode material for supercapacitors. Interestingly, the specific capacitance of the synthesized electrode increases up to the first 1500 charge-discharge cycles, and is thus referred to as an electrode activation process. The activated GCM@PANI nanocomposite electrode exhibits an extraordinary galvanostatic specific capacitance of 3037 F g -1 at a current density of 8 A g -1 . The synthesized nanocomposite exhibits an excellent cyclic stability with a capacitance retention of 83% over 12 000 charge-discharge cycles, and a high rate capability by retaining a specific capacitance of 84.6% at a current density of 20 A g -1 . The structural and electrochemical analysis of the synthesized nanocomposite suggests that the astonishing electrochemical performance might be attributed to the growth of a novel PANI nanoparticle layer and the synergistic effect of CNT/MnO 2 nanostructures.

Facile synthesis of hybrid CNTs/NiCo2S4 composite for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Li, Delong; Gong, Youning; Pan, Chunxu

2016-07-01

In this work, a novel carbon nanotubes (CNTs)/NiCo2S4 composite for high performance supercapacitors was prepared via a simple chemical bath deposition combined with a post-anion exchange reaction. The morphologies and phase structures of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and low-temperature sorption of nitrogen (BET). The electro-chemical tests revealed that the CNT/NiCo2S4 composite exhibited high electrochemical performance, because the CNTs were used as a conductive network for the NiCo2S4 hexagonal nanoplates. Compared with pure NiCo2S4 and the mechanically mixed CNTs/NiCo2S4 composite, the CNTs/NiCo2S4 composite electrode material exhibited excellent supercapacitive performance, such as a high specific capacitance up to 1537 F/g (discharge current density of 1 A/g) and an outstanding rate capability of 78.1% retention as the discharge current density increased to 100 A/g. It is therefore expected to be a promising alternative material in the area of energy storage.

Facile synthesis of hybrid CNTs/NiCo2S4 composite for high performance supercapacitors

PubMed Central

Li, Delong; Gong, Youning; Pan, Chunxu

2016-01-01

In this work, a novel carbon nanotubes (CNTs)/NiCo2S4 composite for high performance supercapacitors was prepared via a simple chemical bath deposition combined with a post-anion exchange reaction. The morphologies and phase structures of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and low-temperature sorption of nitrogen (BET). The electro-chemical tests revealed that the CNT/NiCo2S4 composite exhibited high electrochemical performance, because the CNTs were used as a conductive network for the NiCo2S4 hexagonal nanoplates. Compared with pure NiCo2S4 and the mechanically mixed CNTs/NiCo2S4 composite, the CNTs/NiCo2S4 composite electrode material exhibited excellent supercapacitive performance, such as a high specific capacitance up to 1537 F/g (discharge current density of 1 A/g) and an outstanding rate capability of 78.1% retention as the discharge current density increased to 100 A/g. It is therefore expected to be a promising alternative material in the area of energy storage. PMID:27406239

Facile synthesis of hybrid CNTs/NiCo2S4 composite for high performance supercapacitors.

PubMed

Li, Delong; Gong, Youning; Pan, Chunxu

2016-07-11

In this work, a novel carbon nanotubes (CNTs)/NiCo2S4 composite for high performance supercapacitors was prepared via a simple chemical bath deposition combined with a post-anion exchange reaction. The morphologies and phase structures of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and low-temperature sorption of nitrogen (BET). The electro-chemical tests revealed that the CNT/NiCo2S4 composite exhibited high electrochemical performance, because the CNTs were used as a conductive network for the NiCo2S4 hexagonal nanoplates. Compared with pure NiCo2S4 and the mechanically mixed CNTs/NiCo2S4 composite, the CNTs/NiCo2S4 composite electrode material exhibited excellent supercapacitive performance, such as a high specific capacitance up to 1537 F/g (discharge current density of 1 A/g) and an outstanding rate capability of 78.1% retention as the discharge current density increased to 100 A/g. It is therefore expected to be a promising alternative material in the area of energy storage.

Study of flywheel energy storage for space stations

NASA Technical Reports Server (NTRS)

Gross, S.

1984-01-01

The potential of flywheel systems for space stations using the Space Operations Center (SOC) as a point of reference is discussed. Comparisons with batteries and regenerative fuel cells are made. In the flywheel energy storage concept, energy is stored in the form of rotational kinetic energy using a spinning wheel. Energy is extracted from the flywheel using an attached electrical generator; energy is provided to spin the flywheel by a motor, which operates during sunlight using solar array power. The motor and the generator may or may not be the same device. Flywheel energy storage systems have a very good potential for use in space stations. This system can be superior to alkaline secondary batteries and regenerable fuel cells in most of the areas that are important in spacecraft applications. Of special impotance relative to batteries, are high energy density (lighter weight), longer cycle and operating life, and high efficiency which minimizes the amount of orbital makeup fuel required. In addition, flywheel systems have a long shelf life, give a precise state of charge indication, have modest thermal control needs, are capable of multiple discharges per orbit, have simple ground handling needs, and have the potential for very high discharge rate. Major disadvantages are noted.

A manganese-hydrogen battery with potential for grid-scale energy storage

NASA Astrophysics Data System (ADS)

Chen, Wei; Li, Guodong; Pei, Allen; Li, Yuzhang; Liao, Lei; Wang, Hongxia; Wan, Jiayu; Liang, Zheng; Chen, Guangxu; Zhang, Hao; Wang, Jiangyan; Cui, Yi

2018-05-01

Batteries including lithium-ion, lead-acid, redox-flow and liquid-metal batteries show promise for grid-scale storage, but they are still far from meeting the grid's storage needs such as low cost, long cycle life, reliable safety and reasonable energy density for cost and footprint reduction. Here, we report a rechargeable manganese-hydrogen battery, where the cathode is cycled between soluble Mn2+ and solid MnO2 with a two-electron reaction, and the anode is cycled between H2 gas and H2O through well-known catalytic reactions of hydrogen evolution and oxidation. This battery chemistry exhibits a discharge voltage of 1.3 V, a rate capability of 100 mA cm-2 (36 s of discharge) and a lifetime of more than 10,000 cycles without decay. We achieve a gravimetric energy density of 139 Wh kg-1 (volumetric energy density of 210 Wh l-1), with the theoretical gravimetric energy density of 174 Wh kg-1 (volumetric energy density of 263 Wh l-1) in a 4 M MnSO4 electrolyte. The manganese-hydrogen battery involves low-cost abundant materials and has the potential to be scaled up for large-scale energy storage.

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

Park, Jin-Woo; Kim, Icpyo; Kim, Ki-Won

Highlights: • The sulfur/activated carbon composite is fabricated using commercial activated carbons. • The sulfur/activated carbon composite with coal shows the best performance. • The Li/S battery has capacities of 1240 mAh g{sup −1} at 1 C and 567 mAh g{sup −1} at 10 C. - Abstract: We prepared sulfur/active carbon composites via a simple solution-based process using the following commercial activated carbon-based materials: coal, coconut shells, and sawdust. Although elemental sulfur was not detected in any of the sulfur/activated carbon composites based on Thermogravimetric analysis, X-ray diffraction, and Raman spectroscopy, Energy-dispersive X-ray spectroscopy results confirmed its presence in themore » activated carbon. These results indicate that sulfur was successfully impregnated in the activated carbon and that all of the activated carbons acted as sulfur reservoirs. The sulfur/activated carbon composite cathode using coal exhibited the highest discharge capacity and best rate capability. The first discharge capacity at 1 C (1.672 A g{sup −1}) was 1240 mAh g{sup −1}, and a large reversible capacity of 567 mAh g{sup −1} was observed at 10 C (16.72 A g{sup −1}).« less

Dynamic characteristics of corona discharge generated under rainfall condition on AC charged conductors

NASA Astrophysics Data System (ADS)

Xu, Pengfei; Zhang, Bo; Wang, Zezhong; Chen, Shuiming; He, Jinliang

2017-12-01

By synchronous measurement of corona current and the water droplet deformation process on a conductor surface, different types of corona discharge are visualized when AC voltage is applied on a line-ground electrode system. The corona characteristics are closely related to the applied voltage and water supply rate. With the increase of AC voltage, the positive Taylor cone discharge firstly appears and then disappears, replaced by the dripping and crashing discharge. Furthermore, the number of pulses in each pulse train increases with the increase of applied voltage. The mechanism of the transfer from the positive Taylor cone discharge to the dripping and crashing discharge is found to be related to the oscillation process of the water droplet. The water supply rate also has a great influence on the characteristics of corona currents. The number of positive pulse trains increases linearly when the water supply rate gets larger, leading to a higher audible noise and radio interference level from the AC corona, which is quite different from that of the DC corona. The difference between the AC and DC coronas under rainfall conditions is analyzed finally.

Estimated post-Messinian sediment supply and sedimentation rates on the Ebro continental margin, Spain

USGS Publications Warehouse

Nelson, C.H.

1990-01-01

Because of the extensive data base of seismic profiles, radiometric ages, and stratigraphic time markers such as the subaerial Messinian surface, sedimentation rates and Ebro River sediment discharge can be estimated for different periods and environments of the Ebro continental margin. New values for sediment discharge (i.e., 6.2 versus previous estimates of 2-3.5 million t/yr) for the Holocene highstand are more reliable but remain minimum estimates because a small proportion of Ebro sediment advected to the Balearic Rise and Abyssal Plain cannot be accounted for, especially during lowstands. The general highstand conditions of the Pliocene, which were similar to those of the Holocene, resulted in a low discharge of Ebro River sediment (ca. 6.5 million t/yr) and an even thickness of sediment across the margin that deposited at rates of about 24-40 cm/ky. In contrast, sediment supply increased two-three times during the Pleistocene, the margin prograded rapidly and deposition occurred at rates of 101-165 cm/ky on the outer shelf and slope, but basin floor rates remained anomalously low (21-26 cm/ky) because sediment was drained and broadly dispersed eastward in Valencia Trough. During the late Pleistocene rise of sea level, the main depocenters progressively shifted shoreward and sedimentation rates greatly decreased from 175 cm/ky on the upper slope during the early transgression to 106 cm/ky on the outer shelf and then to 63 cm/ky on the mid-shelf during the late transgression as the river sediment discharge dropped to half by Holocene time. Maximal sedimentation rates occurred in active depocenters of sediment dispersal such as the Holocene delta (370 cm/ky) or the youngest Pleistocene Oropesa channel-levee complex (705 cm/ky) where deposition rates increased by an order of magnitude or more compared to average Ebro shelf (38 cm/ky) or base-of-slope rates in the Pleistocene (21 cm/ky). The sedimentation rates verify the importance of sea-level control on the progressive change in location of depocenters and amount of sediment supply, but Pleistocene climatic change and deforestation alone can be observed to double river sediment discharge. The latter observation helps explain the anomalously high deposition rates in Pleistocene turbidite systems compared with older systems that may be controlled more by tectonic and sea-level changes alone. During the past 2000 years, in contrast, man has controlled deposition in the Ebro margin system, first by deforestation that more than doubled river sediment discharge and shelf deposition rates to equal those of Pleistocene time; and second by dam contruction that reduced sediment discharge to less than 5% of the normal Holocene discharge. Similar recent discharge reductions from the Nile and Rhone Rivers suggest that loss of the majority of the river sediment supply in the Mediterranean Sea may result in significant erosion of biologically and agriculturally important lobate delta areas. ?? 1990.

GASEOUS DISCHARGE DEVICE

DOEpatents

Gow, J.D.

1961-01-10

An extremely compact two-terminal gaseous discharge device is described that is capable of producing neutrons in copious quantities, relatively high energy ions, intense x rays, and the like. Principal novelty resides in the provision of a crossed electric-magnetic field region in the discharge envelope that traps electrons and accelerates them to very high energies to provide an intense ionizing medium adjacent the anode of the device for ionizing gas therein with extremely high efficiency. In addition, the crossed-field trapping region holds the electrons close to the anode whereby the acceleration of ions to the cathode is not materially effected by the electron sheath and the ions assume substantially the full energy of the anodecathode potential drop. (auth)

Numerical modelling of ozone production in a wire-cylinder corona discharge and comparison with a wire-plate corona discharge

NASA Astrophysics Data System (ADS)

Wang, Pengxiang; Chen, Junhong

2009-02-01

The effect of electrode configuration on ozone production in the direct-current corona discharge of dry and humid air is studied by a numerical model that combines the electron distribution in the corona plasma, plasma chemistry and transport phenomena. Two electrode configurations are considered: wire-cylinder discharge with air flowing along the wire axis and wire-plate discharge with air flowing transverse to the wire. The ozone distributions in both types of discharges are compared. For both electrode configurations, the ozone production rate is higher in the negative corona than in the positive corona and it decreases with an increase in relative humidity. More importantly, the detailed ozone distribution in the neighbourhood of the discharge wire, together with the ozone kinetics, reveals the possible difference in the ozone production from the two discharges. With the same operating conditions and sufficiently short flow residence time, the ozone production rate is nearly the same for both electrode configurations. When the flow residence time is longer than the characteristic time for homogeneous ozone destruction, the net ozone production is higher in the wire-cylinder discharge than in the wire-plate discharge due to relatively less ozone destruction.

Vastus lateralis surface and single motor unit EMG following submaximal shortening and lengthening contractions.

PubMed

Altenburg, Teatske M; de Ruiter, Cornelis J; Verdijk, Peter W L; van Mechelen, Willem; de Haan, Arnold

2008-12-01

A single shortening contraction reduces the force capacity of muscle fibers, whereas force capacity is enhanced following lengthening. However, how motor unit recruitment and discharge rate (muscle activation) are adapted to such changes in force capacity during submaximal contractions remains unknown. Additionally, there is limited evidence for force enhancement in larger muscles. We therefore investigated lengthening- and shortening-induced changes in activation of the knee extensors. We hypothesized that when the same submaximal torque had to be generated following shortening, muscle activation had to be increased, whereas a lower activation would suffice to produce the same torque following lengthening. Muscle activation following shortening and lengthening (20 degrees at 10 degrees /s) was determined using rectified surface electromyography (rsEMG) in a 1st session (at 10% and 50% maximal voluntary contraction (MVC)) and additionally with EMG of 42 vastus lateralis motor units recorded in a 2nd session (at 4%-47%MVC). rsEMG and motor unit discharge rates following shortening and lengthening were normalized to isometric reference contractions. As expected, normalized rsEMG (1.15 +/- 0.19) and discharge rate (1.11 +/- 0.09) were higher following shortening (p < 0.05). Following lengthening, normalized rsEMG (0.91 +/- 0.10) was, as expected, lower than 1.0 (p < 0.05), but normalized discharge rate (0.99 +/- 0.08) was not (p > 0.05). Thus, muscle activation was increased to compensate for a reduced force capacity following shortening by increasing the discharge rate of the active motor units (rate coding). In contrast, following lengthening, rsEMG decreased while the discharge rates of active motor units remained similar, suggesting that derecruitment of units might have occurred.

Marine Ship Automatic Identification System (AIS) for Enhanced Coastal Security Capabilities: An Oil Spill Tracking Application

DTIC Science & Technology

2007-09-01

in port, harbor or waterway incidents; and, oil or oily wastes illegally dumped at sea, including illegal discharge of oily bilge or ballast waters ...quantities of oily waste and oily bilge water and sludge at sea using specially installed pipes, which they were careful to have removed and hidden...detailing specifics for oil and bilge water handling equipment, oil hold washing protocols, and a 15 part per million discharge limit of oil content in

Application of a Two-Dimensional Model of Hydrodynamics and Water Quality (CE-QUAL-W2) to Cordell Hull Reservoir, Tennessee

DTIC Science & Technology

1988-08-01

the four navigation projects on the Cumberland River. It houses a run-of- the-river hydropower facility with three hydroturbines capable of producing...a total of 100 MW. Releases from the structure are made primarily through the hydroturbines with a small amount of flow discharged through lockages...intake. The intakes for the hydroturbines are shown in Figure 3. These intakes spanned several layers vertically, and individual discharges for the

Reciprocal functional interactions between the brainstem and the lower spinal cord

PubMed Central

Yazawa, Itaru

2014-01-01

The interplay of the neuronal discharge patterns regarding respiration and locomotion was investigated using electrophysiological techniques in a decerebrate and arterially perfused in situ mouse preparation. The phrenic, tibial, and/or peroneal nerve discharge became clearly organized into discharge episodes of increasing frequency and duration, punctuated by periods of quiescence as the perfusion flow rate increased at room temperature. The modulated sympathetic tone induced by the hyperoxic/normocapnic state was found to activate the locomotor pattern generator (LPG) via descending pathways and generate a left and right alternating discharge during discharge episodes in the motor nerves. The rhythm coupling of respiration and locomotion occurred at a 1:1 frequency ratio. Although the phrenic discharge synchronized with the tibial discharge at all flow rates tested, the time lag between peaks of the two discharges during locomotion was ≈400 ms rather than ≈200 ms, suggesting spinal feedback via ascending pathways. The incidence of the phrenic and tibial discharge episodes decreased by ≈50% after spinalization at the twelfth thoracic cord and the respiratory rhythm was more regular. These results indicate that: (i) locomotion can be generated in a hyperoxic/normocapnic state induced by specific respiratory conditions, (ii) the central mechanism regarding entrainment of respiratory and locomotor rhythms relies on spinal feedback via ascending pathways, initiated by the activated LPG generating locomotion, and (iii) the increase in respiratory rate seen during locomotion is caused not only by afferent mechanical and nociceptive inputs but also by impulses from the activated spinal cord producing a locomotor-like discharge via ascending pathways. PMID:24910591

Discharge Against Medical Advice in the Pediatric Wards in Boo-ali Sina Hospital, Sari, Iran 2010.

PubMed

Mohseni Saravi, Benyamin; Reza Zadeh, Esmaeil; Siamian, Hasan; Yahghoobian, Mahboobeh

2013-12-01

Since children neither comprehended nor contribute to the decision, discharge against medical advice is a challenge of health care systems in the world. Therefore, the current study was designed to determine the rate and causes of discharge against medical advice. This descriptive cross-sectional study was done by reviewing the medical records by census method. Data was analyzed using SPSS software and x(2) statistics was used to determine the relationship between variables. The value of P<0.05 was considered significant. Rate of discharged against medical advice was 108 (2.2%). Mean of age and length of stay were 2.8±4 (SD).3 years old and 3.7±5.4 (SD) days, respectively. Totally, 95 patients (88.7%) had health insurance and 65 (60.2%) patients lived in urban areas. History of psychiatric disease and addiction in 22 (20.6%) of the parents were negative. In addition, 100 (92.3%) patients admitted for medical treatment and the others for surgery. The relationship of the signatory with patients (72.3%) was father. Of 108 patients discharged against medical advice, 20 (12%) were readmitted. The relationship between the day of discharge and discharge against medical advice was significant (ρ =0/03). Rate of discharge against medical advice in Boo-ali hospital is the same as the other studies in the same range. The form which is used for this purpose did not have suitable data elements about description of consequence of such discharge, and it has not shown the real causes of discharge against medical advice.

A Quality Improvement Collaborative to Improve the Discharge Process for Hospitalized Children.

PubMed

Wu, Susan; Tyler, Amy; Logsdon, Tina; Holmes, Nicholas M; Balkian, Ara; Brittan, Mark; Hoover, LaVonda; Martin, Sara; Paradis, Melisa; Sparr-Perkins, Rhonda; Stanley, Teresa; Weber, Rachel; Saysana, Michele

2016-08-01

To assess the impact of a quality improvement collaborative on quality and efficiency of pediatric discharges. This was a multicenter quality improvement collaborative including 11 tertiary-care freestanding children's hospitals in the United States, conducted between November 1, 2011 and October 31, 2012. Sites selected interventions from a change package developed by an expert panel. Multiple plan-do-study-act cycles were conducted on patient populations selected by each site. Data on discharge-related care failures, family readiness for discharge, and 72-hour and 30-day readmissions were reported monthly by each site. Surveys of each site were also conducted to evaluate the use of various change strategies. Most sites addressed discharge planning, quality of discharge instructions, and providing postdischarge support by phone. There was a significant decrease in discharge-related care failures, from 34% in the first project quarter to 21% at the end of the collaborative (P < .05). There was also a significant improvement in family perception of readiness for discharge, from 85% of families reporting the highest rating to 91% (P < .05). There was no improvement in unplanned 72-hour (0.7% vs 1.1%, P = .29) and slight worsening of the 30-day readmission rate (4.5% vs 6.3%, P = .05). Institutions that participated in the collaborative had lower rates of discharge-related care failures and improved family readiness for discharge. There was no significant improvement in unplanned readmissions. More studies are needed to evaluate which interventions are most effective and to assess feasibility in non-children's hospital settings. Copyright © 2016 by the American Academy of Pediatrics.

Patient nonadherence to filling discharge medication prescriptions from the emergency department: Barriers and clinical implications.

PubMed

Farris, Brian; Shakowski, Courtney; Mueller, Scott W; Phong, Suzanne; Kiser, Tyree H; Jacknin, Gabrielle

2018-03-01

Barriers to and clinical implications of patient nonadherence to filling discharge medication prescriptions from the emergency department (ED) were evaluated. This was a retrospective, observational analysis of patients discharged from the ED from April 2013 through May 2015 with medication prescriptions. Patients age 18-89 years who were seen in the ED and did not retrieve discharge medication prescriptions from the onsite, 24-hour ED discharge pharmacy were included in this study. Patients who did not pick up prescriptions were called and asked about barriers to prescription filling. These charts were then retrospectively reviewed and categorized. The primary study outcome was the frequency of nonadherence to filling discharge medications prescribed during the ED visit at the ED outpatient pharmacy. Secondary outcomes included identifying barriers to medication adherence, the rate of return ED visits within 30 days of ED discharge, and the rate of 30-day hospital admissions. Associations between patient and medication variables and the rates of return ED visits within 30 days of discharge and 30-day hospital admissions were analyzed. Of the 4,444 patients discharged from the ED with a prescription to be filled at the satellite pharmacy, 510 were nonadherent. Of these patients, 505 had complete chart information available for evaluation. A large proportion of nonadherent patients revisited the ED within 30 days of ED discharge. Multivariate logistic regression found payer class, ethnicity, and sex were independently associated with return ED visits. The majority of patients who received a prescription during an ED visit filled their discharge medications. Sex, ethnicity, and payer class were independently associated with nonadherence. Copyright © 2018 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

Comparison of FIM™ communication ratings for English versus non-English speakers in the traumatic brain injury model systems (TBIMS) national database.

PubMed

Lequerica, Anthony; Krch, Denise; Lengenfelder, Jean; Chiaravalloti, Nancy; Arango-Lasprilla, Juan Carlos; Hammond, Flora M; O'Neil-Pirozzi, Therese M; Perrin, Paul B; Sander, Angelle M

2015-01-01

To examine the effect of primary language on admission and discharge FIM™ communication ratings in a sample of individuals with moderate-to-severe traumatic brain injury (TBI). Secondary data analysis of rehabilitation admission and discharge FIM™ communication ratings of 2795 individuals hospitalized at a Traumatic Brain Injury Model Systems (TBIMS) centre between 2007-2012. Individuals who spoke no English were rated worse on functional communication outcomes at inpatient rehabilitation discharge relative to individuals whose primary language was English. These findings may reflect systematic bias in FIM™ communication ratings of non-English-speaking individuals with TBI and/or TBI-induced communication difficulties in non-English-speaking individuals. Clinical and research implications are discussed.