WorldWideScience

Sample records for atmospheric channel characteristics

  1. Propagation characteristics of atmospheric-pressure He+O2 plasmas inside a simulated endoscope channel

    International Nuclear Information System (INIS)

    Cold atmospheric-pressure plasmas have potential to be used for endoscope sterilization. In this study, a long quartz tube was used as the simulated endoscope channel, and an array of electrodes was warped one by one along the tube. Plasmas were generated in the inner channel of the tube, and their propagation characteristics in He+O2 feedstock gases were studied as a function of the oxygen concentration. It is found that each of the plasmas originates at the edge of an instantaneous cathode, and then it propagates bidirectionally. Interestingly, a plasma head with bright spots is formed in the hollow instantaneous cathode and moves towards its center part, and a plasma tail expands through the electrode gap and then forms a swallow tail in the instantaneous anode. The plasmas are in good axisymmetry when [O2] ≤ 0.3%, but not for [O2] ≥ 1%, and even behave in a stochastic manner when [O2] = 3%. The antibacterial agents are charged species and reactive oxygen species, so their wall fluxes represent the “plasma dosage” for the sterilization. Such fluxes mainly act on the inner wall in the hollow electrode rather than that in the electrode gap, and they get to the maximum efficiency when the oxygen concentration is around 0.3%. It is estimated that one can reduce the electrode gap and enlarge the electrode width to achieve more homogenous and efficient antibacterial effect, which have benefits for sterilization applications

  2. Propagation characteristics of atmospheric-pressure He+O{sub 2} plasmas inside a simulated endoscope channel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.; Chen, Z. Y.; Wang, X. H., E-mail: xhw@mail.xjtu.edu.cn; Li, D.; Yang, A. J.; Liu, D. X.; Rong, M. Z. [State Key Laboratory of Electrical Insulation and Power Equipment, Centre for Plasma Biomedicine, Xi' an Jiaotong University, Xi' an 710049 (China); Chen, H. L. [Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Kong, M. G. [State Key Laboratory of Electrical Insulation and Power Equipment, Centre for Plasma Biomedicine, Xi' an Jiaotong University, Xi' an 710049 (China); Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529 (United States)

    2015-11-28

    Cold atmospheric-pressure plasmas have potential to be used for endoscope sterilization. In this study, a long quartz tube was used as the simulated endoscope channel, and an array of electrodes was warped one by one along the tube. Plasmas were generated in the inner channel of the tube, and their propagation characteristics in He+O{sub 2} feedstock gases were studied as a function of the oxygen concentration. It is found that each of the plasmas originates at the edge of an instantaneous cathode, and then it propagates bidirectionally. Interestingly, a plasma head with bright spots is formed in the hollow instantaneous cathode and moves towards its center part, and a plasma tail expands through the electrode gap and then forms a swallow tail in the instantaneous anode. The plasmas are in good axisymmetry when [O{sub 2}] ≤ 0.3%, but not for [O{sub 2}] ≥ 1%, and even behave in a stochastic manner when [O{sub 2}] = 3%. The antibacterial agents are charged species and reactive oxygen species, so their wall fluxes represent the “plasma dosage” for the sterilization. Such fluxes mainly act on the inner wall in the hollow electrode rather than that in the electrode gap, and they get to the maximum efficiency when the oxygen concentration is around 0.3%. It is estimated that one can reduce the electrode gap and enlarge the electrode width to achieve more homogenous and efficient antibacterial effect, which have benefits for sterilization applications.

  3. Channel Measurements and Characteristics for Cooperative Positioning Applications

    DEFF Research Database (Denmark)

    Wang, Wei; Steinböck, Gerhard; Jost, Thomas; Pedersen, Troels; Raulefs, Ronald; Fleury, Bernard Henri

    We have conducted an indoor channel measurement campaign to characterize the propagation channel for the development of cooperative positioning algorithms. The campaign focused particularly on the characteristics of multi-link channels with applications to positioning. In this contribution we...

  4. Observed characteristics of Mozambique Channel eddies

    Science.gov (United States)

    Swart, N. C.; Lutjeharms, J. R. E.; Ridderinkhof, H.; de Ruijter, W. P. M.

    2010-09-01

    The flow in the Mozambique Channel is dominated by large, southward propagating, anti-cyclonic eddies, as opposed to a steady western boundary current. These Mozambique Channel eddies feed their waters into the Agulhas Current system, where they are thought to have a significant influence on the formation of the Natal Pulse and Agulhas Ring shedding. Here we use in situ hydrographic and nutrient data, together with satellite altimetry and surface velocity profilers to provide a detailed characterization of the Mozambique Channel eddies. Two warm eddies in the Channel at 20°S and 24°S had diameters of over 200 km. They rotated anti-cyclonically with a tangential velocity of over 0.5 m.s-1. Vertical sections show that the eddies reached to the bottom of the water column. Relative to the surrounding waters, the features were warm and saline. The total heat and salt anomalies for the southernmost eddy were computed relative to a reference station close by. At 24°S the total anomalies were 1.3 × 1020 J and 6.9 × 1012 kg, respectively, being on par with Agulhas rings. Mozambique Channel eddies thus have the potential to form a major contribution to the southward eddy heat flux in the Agulhas Current system. The feature also had positive nutrient and negative oxygen anomalies. The large magnitude of the water mass anomalies within the eddy suggests that interannual variability in Mozambique Channel eddy numbers would have a significant impact on downstream water mass characteristics.

  5. Research on the laser transmission characteristics simulation and comprehensive test in complex channel environment

    Science.gov (United States)

    Fu, Qiang; Liu, Jianhua; Wang, Xiaoman; Jiang, Huilin; Liu, Zhi

    2014-12-01

    The laser transmission characteristics affected in the complex channel environment, which limits the performance of laser equipment and engineering application severely. The article aim at the influence of laser transmission in atmospheric and seawater channels, summarizes the foreign researching work of the simulation and comprehensive test regarding to the laser transmission characteristics in complex environment. And researched the theory of atmospheric turbulence effect, water attenuation features, and put forward the corresponding theoretical model. And researched the simulate technology of atmospheric channel and sea water channel, put forward the analog device plan, adopt the similar theory of flowing to simulate the atmosphere turbulence .When the flowing has the same condition of geometric limits including the same Reynolds, they must be similar to each other in the motivation despite of the difference in the size, speed, and intrinsic quality. On this basis, set up a device for complex channel simulation and comprehensive testing, the overall design of the structure of the device, Hot and Cold Air Convection Simulation of Atmospheric Turbulence, mainly consists of cell body, heating systems, cooling systems, automatic control system. he simulator provides platform and method for the basic research of laser transmission characteristics in the domestic.

  6. Characteristics of discharge at parameters of lightning channel

    International Nuclear Information System (INIS)

    The type of discharges at the atmospheric pressure is studied due to interesting physical features - high conductivity, surface tension of the current channel and forming of a ball structure with lifetime of a few ms and due to security of the airplane components against the lightning. The parameters of different parts of the current channel are presented

  7. Improved Determination of Surface and Atmospheric Temperatures Using Only Shortwave AIRS Channels

    Science.gov (United States)

    Susskind,Joel

    2009-01-01

    AIRS was launched on EOS Aqua on May 4, 2002, together with AMSU-A and HSB, to form a next generation polar orbiting infrared and microwave atmospheric sounding system. AIRS is a grating spectrometer with a number of linear arrays of detectors with each detector sensitive to outgoing radiation in a characteristic frequency v(sub i) with a spectral band pass delta v(sub i) of roughly v(sub i) /1200. AIRS contains 2378 spectral channels covering portions of the spectral region 650 cm(exp -1) (15.38 gm) - 2665 cm(exp -1)' (3.752 micrometers). These spectral regions contain significant absorption features from two CO2 absorption bands, the 15 micrometer (longwave) CO2 band, and the 4.3 micrometer (shortwave) CO, absorption band. There are also two atmospheric window regions, the 12 micrometerm - 8 micrometer (longwave) window, and the 4.17 micrometer - 3.75 micrometer (shortwave) window. Historically, determination of surface and atmospheric temperatures from satellite observations was performed using primarily observations in the longwave window and CO2 absorption regions. One reason for this was concerns about the effects, during the day, of reflected sunlight and non-Local Thermodynamic Equilibrium (non-LTE) on the observed radiances in the shortwave portion of the spectrum. According to cloud clearing theory, more accurate soundings of both surface skin and atmospheric temperatures can be obtained under partial cloud cover conditions if one uses the longwave channels to determine cloud cleared radiances R(sub i) for all channels, and uses R(sub i) only from shortwave channels in the determination of surface and atmospheric temperatures. This procedure is now being used by the AIRS Science Team in preparation for the AIRS Version 6 Retrieval Algorithm. This paper describes how the effects on the radiances of solar radiation reflected by clouds and the Earth's surface, and also of non-LTE, are accounted for in the analysis of the data. Results are presented for both

  8. Influence of space between atmospheric channels and beams' number on scintillation

    Institute of Scientific and Technical Information of China (English)

    Weihui Liu (刘维慧); Jian Wu (吴健)

    2003-01-01

    On the basis of Kolmogorov's theorem, the physical meanings of beams' correlation function on received plane are extended. Approximate formula of channels' across correlation coefficient is deduced from multiple beams through atmosphere. And the scintillation variance of multiple beams is also induced. The result shows along with the channels close to one another, the correlation coefficient increases, and so does the scintillation variance. When the channels completely combine, the scintillation variance of multiple channels is with no difference from that of one channel.

  9. Channel Characteristics and Transmission Performance for Various Channel Configurations at 60 GHz

    Directory of Open Access Journals (Sweden)

    Haibing Yang

    2007-05-01

    Full Text Available Extensive measurements are conducted in room environments at 60 GHz to analyze the channel characteristics for various channel configurations. Channel parameters retrieved from measurements are presented and analyzed based on generic channel models. Particularly, a simple single-cluster model is applied for the parameter retrieval and performance evaluation. By this model, power delay profiles are simply described by a K-factor, a root-mean-squared delay spread, and a shape parameter. The considered channels are configured with the combination of omnidirectional, fan-beam, and pencil-beam antennas at transmitter and receiver sides. Both line-of-sight (LOS and non-LOS (NLOS channels are considered. Further, to evaluate the transmission performance, we analyze the link budget in the considered environments, then design and simulate an OFDM system with a data rate of 2 Gbps to compare the bit-error-rate (BER performance by using the measured and modeled channels. Both coded and uncoded OFDM systems are simulated. It is observed that the BER performance agrees well for the measured and modeled channels. In addition, directive configurations can provide sufficient link margins and BER performance for high data rate communications. To increase the coverage and performance in the NLOS area, it is preferable to apply directive antennas.

  10. Channel Characteristics and Transmission Performance for Various Channel Configurations at 60 GHz

    Directory of Open Access Journals (Sweden)

    Yang Haibing

    2007-01-01

    Full Text Available Extensive measurements are conducted in room environments at 60 GHz to analyze the channel characteristics for various channel configurations. Channel parameters retrieved from measurements are presented and analyzed based on generic channel models. Particularly, a simple single-cluster model is applied for the parameter retrieval and performance evaluation. By this model, power delay profiles are simply described by a -factor, a root-mean-squared delay spread, and a shape parameter. The considered channels are configured with the combination of omnidirectional, fan-beam, and pencil-beam antennas at transmitter and receiver sides. Both line-of-sight (LOS and non-LOS (NLOS channels are considered. Further, to evaluate the transmission performance, we analyze the link budget in the considered environments, then design and simulate an OFDM system with a data rate of 2 Gbps to compare the bit-error-rate (BER performance by using the measured and modeled channels. Both coded and uncoded OFDM systems are simulated. It is observed that the BER performance agrees well for the measured and modeled channels. In addition, directive configurations can provide sufficient link margins and BER performance for high data rate communications. To increase the coverage and performance in the NLOS area, it is preferable to apply directive antennas.

  11. Characteristics of the Martian atmosphere surface layer

    Science.gov (United States)

    Clow, G. D.; Haberle, R. M.

    1991-01-01

    Researchers extend elements of various terrestrial boundary layer models to Mars in order to estimate sensible heat, latent heat, and momentum fluxes within the Martian atmospheric surface layer. To estimate the molecular viscosity and thermal conductivity of a CO2-H2O gas mixture under Martian conditions, parameterizations were developed. Parameterizations for specific heat and and binary diffusivity were also determined. The Prandtl and Schmidt numbers derived from these thermophysical properties were found to range from 0.78 - 1.0 and 0.47 - 0.70, respectively, for Mars. Brutsaert's model for sensible and latent heat transport within the interfacial sublayer for both aerodynamically smooth and rough airflow was experimentally tested under similar conditions, validating its application to Martian conditions. For the surface sublayer, the researchers modified the definition of the Monin-Obukhov length to properly account for the buoyancy forces arising from water vapor gradients in the Martian atmospheric boundary layer. This length scale was then utilized with similarity theory turbulent flux profiles with the same form as those used by Businger et al. and others. It was found that under most Martian conditions, the interfacial and surface sublayers offer roughly comparable resistance to sensible heat and water vapor transport and are thus both important in determining the associated fluxes.

  12. Characteristics Analysis of HFM Signal over Underwater Acoustic Channels

    Directory of Open Access Journals (Sweden)

    YUAN Fei

    2013-01-01

    Full Text Available For pulse compression characteristics and not easily affected by noise, linear frequency modulation signal are widely used in underwater acoustic communication. This paper analyzes the characteristics of hyperbolic frequency modulation signal over underwater acoustic channels. Compared with linear frequency modulation signal, hyperbolic frequency modulation has the same performance of strong anti-noise and anti-multipath, what’s more, hyperbolic frequency modulation signal is better resist the influence of doppler. And discussed the influence of doppler on signal, simulation results show that the hyperbolic frequency modulation signal detection rate is better than linear frequency modulation signal in the doppler environment.

  13. Numerical analysis of flow characteristics of an atmospheric plasma torch

    CERN Document Server

    Kim, Y J; Han, J G; Kim, Youn J.; Kim, You-Jae

    2004-01-01

    The atmospheric plasma is regarded as an effective method for surface treatments because it can reduce the period of process and does not need expensive vacuum apparatus. The performance of non-transferred plasma torches is significantly depended on jet flow characteristics out of the nozzle. In order to produce the high performance of a torch, the maximum discharge velocity near an annular gap in the torch should be maintained. Also, the compulsory swirl is being produced to gain the shape that can concentrate the plasma at the center of gas flow. Numerical analysis of two different mathematical models used for simulating plasma characteristics inside an atmospheric plasma torch is carried out. A qualitative comparison is made in this study to test the accuracy of these two different model predictions of an atmospheric plasma torch. Numerical investigations are carried out to examine the influence of different model assumptions on the resulting plasma characteristics. Significant variations in the results in...

  14. Photoelectric characteristics of photocells with a surface channel

    Energy Technology Data Exchange (ETDEWEB)

    Gorban, A.P.; Litovchenko, V.G.; Popov, V.G.; Serba, A.A.

    1977-07-01

    Results are presented from a study of the photoelectrical characteristics of surface-channel dielectric-semiconductor photocells, illustrating, in particular, their elevated sensitivity in the near ultraviolet region of the spectrum. To prevent high recombination losses, the photocells were made by thermal oxidation of p-type silicon at relatively low temperatures, resulting in a very shallow depth of the induced p-n junction (about 0.1 ..mu..m) without increasing the concentration of recombination-active dopants in the surface zone. The device has a typical photocurrent relaxation time of not over 30 ..mu..s, determined by the impedance of the channel and the conductivity of the base material. 12 references.

  15. Analysis of Channel Luminosity Characteristics in Rocket-Triggered Lightning

    Institute of Scientific and Technical Information of China (English)

    LU Weitao; ZHANG Yijun; ZHOU Xiuji; MENG Qing; ZHENG Dong; MA Ming; WANG Fei; CHEN Shaodong; QIE Xiushu

    2008-01-01

    A comparison is made of the high-speed(2000 fps)photographic records in rocket-triggered negative lightning between two techniques.The analysis shows that:the initial speed of upward positive leader (UPL)in altitude-triggered negative lightning(ATNL)is about one order of magnitude less than that in classically triggered negative lightning(CTNL),while the triggering height of ATNL is higher than that of CTNL;the afterglow time of metal-vaporized part of the lightning channel Call endure for about 160-170 ms,thus the luminosity of the air-ionized part can reflect the characteristics of the current in the lightning channel better than that of the metal-vaporized part.According to the different characteristics of the luminosity change of the lightning channel,together with the observation of the electric field changes,three kinds of processes after return-stroke(RS)can be distinguished:the continuous decaying type without M component,the isolated type and the continuing type with M component,corresponding to different wave shapes of the continuous current.The geometric mean of the interval of RS with M component is 77 ms,longer than that(37 ms)of RS without M component.And the initial continuous current(ICC)with M component also has a longer duration compared to the ICC without M component.The distinction in the relative luminosity between the lightning channel before RS and that before M component is obvious:the former is very weak or even cannot be observed,while the latter is still considerably luminous.

  16. Empirical Formulation of Flow Characteristics in Trapezoidal Channels

    Science.gov (United States)

    Gandhi, S.; Singh, R. P.

    2016-05-01

    Empirical relations for hydraulic jump characteristics, viz. sequent depth ratio (Y2/Y1), efficiency of jump (E2/E1) and relative length of jump (Lj/Y1) in trapezoidal channel with/without appurtenances are developed by introducing dimensionless Reynolds number, and neglecting the frictional effect for approach Froude number (varied between 2 and 10 under different conditions). Developed empirical models were also validated and compared with acquired experimental data as well as with literature data. Close fitness of the empirical models with appurtenances under varying dimensions, positions of baffle blocks provides accurate prediction of same for higher value of Froude number.

  17. Emulating Spatial Characteristics of MIMO Channels for OTA Testing

    DEFF Research Database (Denmark)

    Fan, Wei; Carreño, Xavier; Sun, Fan; Nielsen, Jesper Ødum; Knudsen, Mikael B.; Pedersen, Gert Frølund

    2013-01-01

    This paper discusses over the air (OTA) testing for multiple input multiple output (MIMO) capable terminals with emphasis on channel spatial characteristics emulation. A novel technique to obtain optimum power weights for the OTA probes based on convex optimization is proposed. The proposed...... technique emulates spatial correlation as well as introduces constraints on the maximum deviation between the target power azimuth spectrum (PAS) and the emulated PAS in terms of mean angle of arrival (AoA) and azimuth spread (AS). Simulation results show that the proposed emulation technique present better...

  18. Atmospheric Quantum Channels with Weak and Strong Turbulence.

    Science.gov (United States)

    Vasylyev, D; Semenov, A A; Vogel, W

    2016-08-26

    The free-space transfer of high-fidelity optical signals between remote locations has many applications, including both classical and quantum communication, precision navigation, clock synchronization, etc. The physical processes that contribute to signal fading and loss need to be carefully analyzed in the theory of light propagation through the atmospheric turbulence. Here we derive the probability distribution for the atmospheric transmittance including beam wandering, beam shape deformation, and beam-broadening effects. Our model, referred to as the elliptic beam approximation, applies to weak, weak-to-moderate, and strong turbulence and hence to the most important regimes in atmospheric communication scenarios. PMID:27610835

  19. Atmospheric Quantum Channels with Weak and Strong Turbulence

    CERN Document Server

    Vasylyev, D; Vogel, W

    2016-01-01

    The free-space transfer of high-fidelity optical signals between remote locations has many applications, including both classical and quantum communication, precision navigation, clock synchronization, etc. The physical processes that contribute to signal fading and loss need to be carefully analyzed in the theory of light propagation through the atmospheric turbulence. Here we derive the probability distribution for the atmospheric transmittance including beam-wandering, beam shape deformation, and beam broadening effects. Our model, referred to as elliptic beam approximation, applies to both weak and strong turbulence and hence to the most important regimes in atmospheric communication scenarios.

  20. Characteristics of RF Cold Plasma at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    QIU Liang; MENG Yuedong; SHU Xingsheng

    2007-01-01

    The characteristics of a stable discharge at atmospheric pressure is investigated.The plasma source consisted of two closely spaced parallel-plated perforated electrodes,driven by a radio frequency power to generate a uniform cold plasma in Helium at atmospheric pressure.Both alpha and gamma modes were clearly observed.The hollow cathode effects were found in the discharge.The influence of the dielectric barrier on the discharge was also investigated by utilizing a surface-anodized aluminium electrode as the anode.

  1. Atmospheric Boundary Layer Characteristics during BOBMEX-Pilot Experiment

    Indian Academy of Sciences (India)

    G S Bhat; S Ameenulla; M Venkataramana; K Sengupta

    2000-06-01

    The atmospheric boundary layer characteristics observed during the BOBMEX-Pilot experiment are reported. Surface meteorological data were acquired continuously through an automatic weather monitoring system and manually every three hours. High resolution radiosondes were launched to obtain the vertical thermal structure of the atmosphere. The study area was convectively active, the SSTs were high, surface air was warm and moist, and the surface air moist static energy was among the highest observed over the tropical oceans. The mean sea air temperature difference was about 1.25°C and the sea skin temperature was cooler than bucket SST by 0.5°C. The atmospheric mixed layer was shallow, fluctuated in response to synoptic conditions from 100 m to 900 m with a mean around 500 m.

  2. Analysis of pressure drop characteristic in supercritical water channel

    International Nuclear Information System (INIS)

    Supercritical water-cooled reactor (SCWR) is one of the fourth generation nuclear energy systems with the supercritical water as the reactor coolant and moderator. The sharp variation of fluid property near the pseudo-critical point will have influence on the pressure drop characteristics of the flow channel. In this study, the pressure drops due to gravity, acceleration and friction were investigated under supercritical conditions and some suggestions were provided as reference. The flow path integration effect in gravity pressure drop needed to be accounted for. The explicit PKN formula was obtained based on the implicit PKN form which could be applied into isothermal flow. The comparison of different frictional pressure drop correlations with CFD numerical simulation results was made, and it is found that the Kirillov correlation is close to CFD calculation results. (authors)

  3. Quality characteristics of the radish grown under reduced atmospheric pressure

    Science.gov (United States)

    Levine, Lanfang H.; Bisbee, Patricia A.; Richards, Jeffrey T.; Birmele, Michele N.; Prior, Ronald L.; Perchonok, Michele; Dixon, Mike; Yorio, Neil C.; Stutte, Gary W.; Wheeler, Raymond M.

    This study addresses whether reduced atmospheric pressure (hypobaria) affects the quality traits of radish grown under such environments. Radish (Raphanus sativus L. cv. Cherry Bomb Hybrid II) plants were grown hydroponically in specially designed hypobaric plant growth chambers at three atmospheric pressures; 33, 66, and 96 kPa (control). Oxygen and carbon dioxide partial pressures were maintained constant at 21 and 0.12 kPa, respectively. Plants were harvested at 21 days after planting, with aerial shoots and swollen hypocotyls (edible portion of the radish referred to as the “root” hereafter) separated immediately upon removal from the chambers. Samples were subsequently evaluated for their sensory characteristics (color, taste, overall appearance, and texture), taste-determining factors (glucosinolate and soluble carbohydrate content and myrosinase activity), proximate nutrients (protein, dietary fiber, and carbohydrate) and potential health benefit attributes (antioxidant capacity). In roots of control plants, concentrations of glucosinolate, total soluble sugar, and nitrate, as well as myrosinase activity and total antioxidant capacity (measured as ORACFL), were 2.9, 20, 5.1, 9.4, and 1.9 times greater than the amount in leaves, respectively. There was no significant difference in total antioxidant capacity, sensory characteristics, carbohydrate composition, or proximate nutrient content among the three pressure treatments. However, glucosinolate content in the root and nitrate concentration in the leaf declined as the atmospheric pressure decreased, suggesting perturbation to some nitrogen-related metabolism.

  4. Experimental round for research thermohydraulic characteristics channels with complex geometry

    International Nuclear Information System (INIS)

    In the paper description of experimental loop for thermohydraulic investigations of fluid flow in channel with complex geometry is given. Loop is assignment for experimental research thermic and hydrodynamic phenomena for one and two-phase one and two-component fluid flow in channels. Loop is designed and performed for void range of thermohydraulic parameters and long evaporation channels with complex geometry. (author)

  5. Surface wave propagation characteristics in atmospheric pressure plasma column

    International Nuclear Information System (INIS)

    In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency (ν/ω) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption ν/ω = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary ν/ω. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance

  6. Surface wave propagation characteristics in atmospheric pressure plasma column

    Science.gov (United States)

    Pencheva, M.; Benova, E.; Zhelyazkov, I.

    2007-04-01

    In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency (ν/ω) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption ν/ω = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary ν/ω. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance.

  7. Surface wave propagation characteristics in atmospheric pressure plasma column

    Energy Technology Data Exchange (ETDEWEB)

    Pencheva, M [Faculty of Physics, Sofia University, 5 James Bourchier Blvd., BG-1164 Sofia (Bulgaria); Benova, E [Department for Language Teaching and International Students, Sofia University, 27 Kosta Loulchev Street, BG-1111 Sofia (Bulgaria); Zhelyazkov, I [Faculty of Physics, Sofia University, 5 James Bourchier Blvd., BG-1164 Sofia (Bulgaria)

    2007-04-15

    In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency ({nu}/{omega}) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption {nu}/{omega} = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary {nu}/{omega}. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance.

  8. CHARACTERISTICS OF FLOW RESISTANCE IN OPEN CHANNELS WITH NON-SUBMERGED RIGID VEGETATION

    Institute of Scientific and Technical Information of China (English)

    WU Fu-sheng

    2008-01-01

    The flow resistance factors of non-submerged rigid vegetation in open channels were analyzed. The formulas of drag coefficient CD and equivalent Manning's roughness coefficient nd were derived by analyzing the force of the flow of non-submerged rigid vegetation in open channel. The flow characteristics and mechanism of non-submerged rigid vegetation in open channel were studied through flume experiments.

  9. Channel characteristics and coordination in three-echelon dual-channel supply chain

    Science.gov (United States)

    Saha, Subrata

    2016-02-01

    We explore the impact of channel structure on the manufacturer, the distributer, the retailer and the entire supply chain by considering three different channel structures in radiance of with and without coordination. These structures include a traditional retail channel and two manufacturer direct channels with and without consistent pricing. By comparing the performance of the manufacturer, the distributer and the retailer, and the entire supply chain in three different supply chain structures, it is established analytically that, under some conditions, a dual channel can outperform a single retail channel; as a consequence, a coordination mechanism is developed that not only coordinates the dual channel but also outperforms the non-cooperative single retail channel. All the analytical results are further analysed through numerical examples.

  10. Performance Analysis of Free-Space Optical Communication Systems With Multiuser Diversity Over Atmospheric Turbulence Channels

    KAUST Repository

    Yang, Liang

    2014-04-01

    Free-space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short-range applications. To address this, we propose a multiuser diversity (MD) FSO scheme in which the Nth best user is selected and the channel fluctuations can be effectively exploited to produce a selection diversity gain. More specifically, we first present the statistics analysis for the considered system over both weak and strong atmospheric turbulence channels. Based on these statistics, the outage probability, bit-error rate performance, average capacity, diversity order, and coverage are analyzed. Results show that the diversity order for the gamma-gamma fading is N min{α, β}/2, where N is the number of users, and α and β are the channel fading parameters related to the effective atmospheric conditions of the link.

  11. Chaotic characteristics of corona discharges in atmospheric air

    International Nuclear Information System (INIS)

    A point-plane electrode system in atmospheric air is established to investigate the mechanism of the corona discharge. By using this system, the current pulses of the corona discharges under the 50 Hz ac voltage are measured using partial discharge (PD) measurement instrument and constitute the point-plane voltage-current (V-I) characteristic equation together with the voltage. Then, this paper constructs the nonlinear circuit model and differential equations of the system in an attempt to give the underlying dynamic mechanism based on the nonlinear V-I characteristics of the point-plane corona discharges. The results show that the chaotic phenomenon is found in the corona circuit by the experimental study and nonlinear dynamic analysis. The basic dynamic characteristics, including the Lyapunov exponent, the existence of the strange attractors, and the equilibrium points, are also found and analyzed in the development process of the corona circuit. Moreover, the time series of the corona current pulses obtained in the experiment is used to demonstrate the chaotic characteristics of the corona current based on the nonlinear dynamic circuit theory and the experimental basis. It is pointed out that the corona phenomenon is not a purely stochastic phenomenon but a short term deterministic chaotic activity

  12. Analytical determination of flow resistance characteristic for combination channel inside hydraulic manifold block

    Institute of Scientific and Technical Information of China (English)

    Wang Yongan; Tian Shujun; Jia Chunqiang; Cao Yuning

    2008-01-01

    Computational fluid dynamics (CFD) was used in conjunction with BP neural network to study the flow resistance characteristic of the combination-channel inside hydraulic manifold block (HMB).The in put parameters of the combination-channel model were confirmed to have effect on the pressure-drop by the numerical method, and a BP neural network model was accordingly constructed to predict the channel pressure-drops.The flow resistance characteristic curves of various channels were achieved, and a performance parameter was given to evaluate the through-flow characteristic of the channel according to the curves.The predictions are in agreement with the numerical computation, indicating that the method can be utilized to accurately determine the flow characteristic of the combination channel with high efficiency.

  13. Temperature distribution and evolution characteristic in lightning return stroke channel

    Science.gov (United States)

    Mu, Yali; Yuan, Ping; Wang, Xuejuan; Dong, Caixia

    2016-07-01

    According to the time-resolved spectra of four lightning return strokes, the temperatures of arc core channel and the peripheral optical channel surrounding the arc core are investigated by different methods; the temperature distribution along the radial direction of channel on the peak current stage is discussed. The results show that a temperature gradient is formed along the radial direction of channel during the discharge process. With the increasing of the radius, the temperature decreases gradually. The temperature of arc core channel is about 4000-5000 K higher than that of the peripheral optical channel. The time evolution of channel temperature shows that the falling of the temperature is very slow compared with the decreasing of the current after their peak values. After the peak current, the channel temperature is still maintained at around 20,000 K up to 200-400 μ s . The heat effect resulting from such a long-time high temperature is the main source of most direct lightning disasters.

  14. Two-dimensional simulation of discharge channels in atmospheric-pressure single dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiao; Wang, Yanhui, E-mail: wangyh@dlut.edu.cn; Wang, Dezhen, E-mail: wangdez@dlut.edu.cn [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2015-11-15

    A two-dimensional fluid model is developed to study the filaments (or discharge channels) in atmospheric-pressure discharge with one plate electrode covered by a dielectric layer. Under certain discharge parameters, one or more stable filaments with wide radii could be regularly arranged in the discharge space. Different from the short-lived randomly distributed microdischarges, this stable and thick filament can carry more current and have longer lifetime. Because only one electrode is covered by a dielectric layer in the simulation, the formed discharge channel extends outwards near the dielectric layer and shrinks inwards near the naked electrode, agreeing with the experimental results. In this paper, the evolution of channel is studied, and its behavior is like a streamer or an ionization wave, but the propagation distance is short. The discharge parameters such as voltage amplitude, electrode width, and N{sub 2} impurities content could significantly influence the number of discharge channel, which is discussed in the paper.

  15. Low SNR Capacity of FSO Links over Gamma-Gamma Atmospheric Turbulence Channels

    KAUST Repository

    Benkhelifa, Fatma

    2013-02-23

    In this paper, we study the ergodic capacity of free space optical communication systems over Gamma-Gamma atmospheric turbulence fading channels with perfect channel state information at both the transmitter and the receiver. In our framework, we mainly focus on the low signal-to-noise ratio range and show that the ergodic capacity scales proportionally to SNR log^4(1/SNR). We show also that one-bit CSI feedback at the transmitter is enough to achieve this capacity using an on-off power control scheme.

  16. Low SNR Capacity of FSO Links over Gamma-Gamma Atmospheric Turbulence Channels

    KAUST Repository

    Benkhelifa, Fatma

    2013-01-27

    In this paper, we study the ergodic capacity of free space optical communication systems over Gamma-Gamma atmospheric turbulence fading channels with perfect channel state information at both the transmitter and the receiver. In our framework, we mainly focus on the low signal-to-noise ratio range and show that the ergodic capacity scales proportionally to SNR log^4(1/SNR). We show also that one-bit CSI feedback at the transmitter is enough to achieve this capacity using an on-o ff power control scheme.

  17. Radiative characteristics for atmospheric models from lidar sounding and AERONET

    Science.gov (United States)

    Sapunov, Maxim; Kuznetsov, Anatoly; Efremenko, Dmitry; Bochalov, Valentin; Melnikova, Irina; Samulenkov, Dimity; Vasilyev, Alexander; Poberovsky, Anatoly; Frantsuzova, Inna

    2016-04-01

    Optical models of atmospheric aerosols above of St. Petersburg are constraint on the base of the results of lidar sounding. The lidar system of the Resource Center "Observatory of environmental safety" of the St. Petersburg University Research Park is situated the city center, Vasilievsky Island. The measurements of the vertical profile of velocity and wind direction in the center of St. Petersburg for 2014 -2015 are fulfilled in addition. Height of laser sounding of aerosols is up to 25 km and wind up to 12 km. Observations are accomplished in the daytime and at night and mapped to vertical profiles of temperature, humidity, wind speed and pressure obtained from radiosounding in Voeikovo (St. Petersburg suburb). Results of wind observations are compared with those of upper-air measurements of meteorological service in Voeikovo. The distance between the points of observation is 25 km. Statistics of wind directions at different heights are identified. The comparison is based on the assumption of homogeneity of the wind field on such a scale. In most cases, good agreement between the observed vertical profiles of wind, obtained by both methods is appeared. However, there were several cases, when the results differ sharply or at high altitudes, or, on the contrary, in the surface layer. The analysis of the impact of wind, temperature, and humidity profiles in the atmosphere on the properties and dynamics of solid impurities is implemented. Comparison with AOT results from AERONET observations in St. Petersburg suburb Peterhof is done. It is shown that diurnal and seasonal variations of optical and morphological parameters of atmospheric aerosols in the pollution cap over the city to a large extent determined by the variability of meteorological parameters. The results of the comparison are presented and possible explanation of the differences is proposed. Optical models of the atmosphere in day and night time in different seasons are constructed from lidar and AERONET

  18. Discharge characteristics and hydrodynamics behaviors of atmospheric plasma jets produced in various gas flow patterns

    Science.gov (United States)

    Setsuhara, Yuichi; Uchida, Giichiro; Nakajima, Atsushi; Takenaka, Kosuke; Koga, Kazunori; Shiratani, Masaharu

    2015-09-01

    Atmospheric nonequilibrium plasma jets have been widely employed in biomedical applications. For biomedical applications, it is an important issue to understand the complicated mechanism of interaction of the plasma jet with liquid. In this study, we present analysis of the discharge characteristics of a plasma jet impinging onto the liquid surface under various gas flow patterns such as laminar and turbulence flows. For this purpose, we analyzed gas flow patters by using a Schlieren gas-flow imaging system in detail The plasma jet impinging into the liquid surface expands along the liquid surface. The diameter of the expanded plasma increases with gas flow rate, which is well explained by an increase in the diameter of the laminar gas-flow channel. When the gas flow rate is further increased, the gas flow mode transits from laminar to turbulence in the gas flow channel, which leads to the shortening of the plasm-jet length. Our experiment demonstrated that the gas flow patterns strongly affect the discharge characteristics in the plasma-jet system. This study was partly supported by a Grant-in-Aid for Scientific Research on Innovative Areas ``Plasma Medical Innovation'' (24108003) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).

  19. Research on diversity receive technology for wireless optical communication using PPM in weak turbulence atmosphere channel

    Science.gov (United States)

    Liu, Yang; Zhang, Guo-an

    2014-09-01

    In order to mitigate atmospheric turbulence, the free space optical (FSO) system model with spatial diversity is analyzed based on intensity detection pulse position modulation (PPM) in the weak turbulence atmosphere. The slot error rate (SER) calculating formula of the system without diversity is derived under pulse position modulation firstly. Then as a benchmark, independent of identical distribution, the average slot error rates of the three linear combining technologies, which are the maximal ratio combining (MRC), equal gain combining (EGC) and selection combining (SelC), are compared. Simulation results show that the performance of system is the best improved by MRC, followed by EGC, and is poor by SelC, but SelC is simpler and more convenient. Spatial diversity is efficient to improve the performance and has strong ability on resistance to atmospheric channel decline. The above scheme is more suitable for optical wireless communication systems.

  20. Basic characteristics of an atmospheric pressure rf generated plasma jet

    Institute of Scientific and Technical Information of China (English)

    Wang Shou-Guo; Li Hai-Jiang; Ye Tian-Chun; Zhao Ling-Li

    2004-01-01

    A plasma jet has been developed which operates using radio frequency (rf) power and produces a stable homogeneous discharge at atmospheric pressure. Its discharge characteristics, especially the dependence of stable discharge operating range on the feed gas, were studied, and the electric parameters such as RMS current, RMS voltage and reflected power were obtained with different gas flows. These studies indicate that there is an optimum range of operation of the plasma jet for a filling with a gas mixture of He and O2. Two "failure" modes of the discharge are identified.One is a filamentary arc when the input power is raised above a critical level, another is that the discharge disappears gradually as the addition of O2 approaches 3.2%. Possible explanations for the two failure modes have been given. The current and voltage waveform measurements show that there is a clear phase shift between normal and failure modes.In addition, Ⅰ-Ⅴ curves as a function of pure helium and for 1% addition of oxygen have been studied.

  1. Gas flow dependence of atmospheric pressure plasma needle discharge characteristics

    Science.gov (United States)

    Qian, Muyang; Yang, Congying; Liu, Sanqiu; Chen, Xiaochang; Ni, Gengsong; Wang, Dezhen

    2016-04-01

    In this paper, a two-dimensional coupled model of neutral gas flow and plasma dynamics is presented to explain the gas flow dependence of discharge characteristics in helium plasma needle at atmospherics pressure. The diffusional mixing layer between the helium jet core and the ambient air has a moderate effect on the streamer propagation. The obtained simulation results present that the streamer shows the ring-shaped emission profile at a moderate gas flow rate. The key chemical reactions which drive the streamer propagation are electron-impact ionization of helium neutral, nitrogen and oxygen molecules. At a moderate gas flow rate of 0.5 slm, a significant increase in propagation velocity of the streamer is observed due to appropriate quantity of impurities air diffuse into the helium. Besides, when the gas flow rate is below 0.35 slm, the radial density of ground-state atomic oxygen peaks along the axis of symmetry. However, when the gas flow rate is above 0.5 slm, a ring-shaped density distribution appears. The peak density is on the order of 1020 m-3 at 10 ns in our work.

  2. Attribution of atmospheric sulfur dioxide over the English Channel to dimethyl sulfide and changing ship emissions

    Science.gov (United States)

    Yang, Mingxi; Bell, Thomas G.; Hopkins, Frances E.; Smyth, Timothy J.

    2016-04-01

    Atmospheric sulfur dioxide (SO2) was measured continuously from the Penlee Point Atmospheric Observatory (PPAO) near Plymouth, United Kingdom, between May 2014 and November 2015. This coastal site is exposed to marine air across a wide wind sector. The predominant southwesterly winds carry relatively clean background Atlantic air. In contrast, air from the southeast is heavily influenced by exhaust plumes from ships in the English Channel as well as near Plymouth Sound. A new International Maritime Organization (IMO) regulation came into force in January 2015 to reduce the maximum allowed sulfur content in ships' fuel 10-fold in sulfur emission control areas such as the English Channel. Our observations suggest a 3-fold reduction in ship-emitted SO2 from 2014 to 2015. Apparent fuel sulfur content calculated from coincidental SO2 and carbon dioxide (CO2) peaks from local ship plumes show a high level of compliance to the IMO regulation (> 95 %) in both years (˜ 70 % of ships in 2014 were already emitting at levels below the 2015 cap). Dimethyl sulfide (DMS) is an important source of atmospheric SO2 even in this semi-polluted region. The relative contribution of DMS oxidation to the SO2 burden over the English Channel increased from about one-third in 2014 to about one-half in 2015 due to the reduction in ship sulfur emissions. Our diel analysis suggests that SO2 is removed from the marine atmospheric boundary layer in about half a day, with dry deposition to the ocean accounting for a quarter of the total loss.

  3. Model evaluation of flow boiling heat characteristics calculation in narrow rectangular channels

    International Nuclear Information System (INIS)

    Both the flow boiling heat transfer characteristics and its influence factors in narrow rectangular channel were studied experimentally. The applicability of the empirical correlations for calculating boiling heat transfer was evaluated against the experimental data. The results show that the effect of the mass flux appears to be primary, the heat transfer coefficients increase with the mass flux under the same void fraction. The correlations based on conventional channels are not suitable for mini-channels very much. The LEELEE correlation based on narrow channels give better agreement than the other evaluated. (authors)

  4. Vertical profiles of atmospheric fluorescent aerosols observed by a mutil-channel lidar spectrometer system

    Science.gov (United States)

    Huang, Z.; Huang, J.; Zhou, T.; Sugimoto, N.; Bi, J.

    2015-12-01

    Zhongwei Huang1*, Jianping Huang1, Tian Zhou1, Nobuo Sugimoto2, Jianrong Bi1 and Jinsen Shi11Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China. 2Atmospheric Environment Division, National Institutes for Environmental Studies, Tsukuba, Japan Email: huangzhongwei@lzu.edu.cn Abstract Atmospheric aerosols have a significant impact on regional and globe climate. The challenge in quantifying aerosol direct radiative forcing and aerosol-cloud interactions arises from large spatial and temporal heterogeneity of aerosol concentrations, compositions, sizes, shape and optical properties (IPCC, 2007). Lidar offers some remarkable advantages for determining the vertical structure of atmospheric aerosols and their related optical properties. To investigate the characterization of atmospheric aerosols (especially bioaerosols) with high spatial and temporal resolution, we developed a Raman/fluorescence/polarization lidar system employed a multi-channel spectrometer, with capabilities of providing measurements of Raman scattering and laser-induced fluorescence excitation at 355 nm from atmospheric aerosols. Meanwhile, the lidar system operated polarization measurements both at 355nm and 532nm wavelengths, aiming to obtain more information of aerosols. It employs a high power pulsed laser and a received telescope with 350mm diameter. The receiver could simultaneously detect a wide fluorescent spectrum about 178 nm with spectral resolution 5.7 nm, mainly including an F/3.7 Crossed Czerny-Turner spectrograph, a grating (1200 gr/mm) and a PMT array with 32 photocathode elements. Vertical structure of fluorescent aerosols in the atmosphere was observed by the developed lidar system at four sites across northwest China, during 2014 spring field observation that conducted by Lanzhou University. It has been proved that the developed lidar could detect the fluorescent aerosols with high temporal and

  5. Combustion and emissions characteristics of dual-channel double-vortex combustion for gas turbine engines

    International Nuclear Information System (INIS)

    Highlights: • A novel double-vortex combustor with a dual channel was designed. • The preheating effect of the evaporation tube is conducive to improving the combustion and emissions performance. • The combustion organization method of the combustor is reasonable. • The staged method significantly affects the performance of the combustor. - Abstract: A vortex combustor is a novel gas turbine combustor that uses staged combustion technology. Research examining the combustion organization method of the pilot combustion zone and the mainstream combustion zone is an important component of the design of the structure of a vortex combustor. In this paper, a new type of single-cavity vortex combustor fueled with aviation kerosene is presented. A double-vortex flow field structure and an evaporation tube for the fuel supply are used in the pilot zone. The flow-field structure of a double recirculation zone and a pneumatic atomization injector for the fuel supply are used in the mainstream combustion zone. The combustion experiment was performed under atmospheric pressure. The influence of the air-flow parameters, fuel parameters and staged method on the combustion performance and the characteristics of the pollutant emissions were studied in detail. Research indicates that the inlet temperature and the staged method primarily influence the ignition limit, lean blowout, combustion efficiency, temperature distribution of the outlet and pollutant emissions. The equivalence ratio primarily influences the temperature distribution of the wall and pollutant emissions. The inlet velocity influences the total pressure loss of the combustor

  6. Studying the operation characteristics and structure of vertical channel copper-phthalocyanine organic semiconductor transistor

    Institute of Scientific and Technical Information of China (English)

    ZHU Min; SONG Ming-xin; GUI Tai-long; WANG Xuan; YIN Jing-hua; WANG Dong-xing; ZHAO Hong

    2005-01-01

    The creation of Au/CuPc/Al/CuPc/structure is a perpendicular type electricity found in the channel of organic static induction transistor. In the following we analyze transistor operation characteristics and machine structural relation. The results express that the transistor drives the voltage low and has no-saturation currentvoltage characteristics. Its operation characteristics are dependant on gate bias voltage and the construction of the aluminum electrode.The vertical channel of organic static induction transistor (OSIT) , with structure of Au/CuPc/Al/CuPc/Cu, has been determined. According to the test results, the relation of its operation characteristics and device structure was analyzed. The results show that this transistor has a low driving voltage and unsaturation Ⅰ-Ⅴ characteristics. Its operation characteristics are dependant on gate bias voltage and the structure of the aluminum electrode.

  7. Novel formulation of the ℳ model through the Generalized-K distribution for atmospheric optical channels.

    Science.gov (United States)

    Garrido-Balsells, José María; Jurado-Navas, Antonio; Paris, José Francisco; Castillo-Vazquez, Miguel; Puerta-Notario, Antonio

    2015-03-01

    In this paper, a novel and deeper physical interpretation on the recently published Málaga or ℳ statistical distribution is provided. This distribution, which is having a wide acceptance by the scientific community, models the optical irradiance scintillation induced by the atmospheric turbulence. Here, the analytical expressions previously published are modified in order to express them by a mixture of the known Generalized-K and discrete Binomial and Negative Binomial distributions. In particular, the probability density function (pdf) of the ℳ model is now obtained as a linear combination of these Generalized-K pdf, in which the coefficients depend directly on the parameters of the ℳ distribution. In this way, the Málaga model can be physically interpreted as a superposition of different optical sub-channels each of them described by the corresponding Generalized-K fading model and weighted by the ℳ dependent coefficients. The expressions here proposed are simpler than the equations of the original ℳ model and are validated by means of numerical simulations by generating ℳ -distributed random sequences and their associated histogram. This novel interpretation of the Málaga statistical distribution provides a valuable tool for analyzing the performance of atmospheric optical channels for every turbulence condition. PMID:25836855

  8. TRANSPORT CHARACTERISTICS OF REPRESENTATIVE DEBRIS IN A OPEN CHANNEL

    International Nuclear Information System (INIS)

    During LOCA(Loss of Coolant Accident), emergency core coolant supplements form a recirculation sump and cooled core and containment. When the double ended guillotine Break (DEGB) at the hot leg near steam generator, due to the jet impingement discharge flow, the debris could be potentially generated at pipe or wall nearby steam generator and be transported to the recirculation sump. Therefore, the debris could be accumulated and be clogged in the recirculation sump screen. If debris blocked the sump screen, the pressure drop increased at the screen so as to increase the pressure loss of ECCS (Emergency Core Cooling System) pump NPSH (Net positive suction head). It is potentially influenced to decrease the long-term cooling capability of the recirculation sump. The recirculation sump screen clogging accident has happened in BWR at 1990. Considering the important of safety, US NRC published Regulatory Guide 1.82 Rev.3 incorporating the R and D findings and experiences in 2003. NEI introduced the methodology procedure to solve this safety issue in the NEI 04-07 report. In the meanwhile, US NRC also published individually the regulatory guidelines as a SER (Safety Evaluation Report) report for PWR plant. However, the current available technical information including the reports is applicable to the generic PWR plants not the plant specific plant. Therefore, the additional research reflecting characteristics of plant specific plant is necessary to develop the methodology and technical guides on the recirculation sump clogging issue. The objective of this study explores the characteristics of debris tumbling velocity during LOCA

  9. Characteristics Analysis of Vertical Double Gate Strained Channel Heterostructure Metal-Oxide-Semiconductor-Field-Effect-Transistor

    Institute of Scientific and Technical Information of China (English)

    YANG Yuan; LI Gui-Ping; GAO Yong; LIU Jing

    2009-01-01

    Since device feature size shrinks continuously, there appears various short-channel effects on the fabrication and performance of devices and integrated circuits. We present a vertical double gate (VDG) strained channel heterostructure metal-oxide-semiconductor-field-effect-transistor (MOSFET). The electrical characteristics of the device with the effective gate length scaled down to 60nm are simulated. The results show that the drive current and transconductance are improved by 57.92% and 54.53% respectively, and grid swing is decreased by 36.83% over their unstrained counterparts. VDG MOSFETs exhibit a stronger capability to restrict short-channel-effects over traditional MOSFETs.

  10. Measurement of the dynamic characteristics of atmospheric diffusion

    International Nuclear Information System (INIS)

    A new method is proposed for studying the diffusion of atmospheric pollutants above real sites which considers the actual magnitudes encountered. The dynamic application of this method yields original information. In view of justifying the method, fundamental theories concerning diffusion are presented together with different models for the atmosphere. The atmosphere is then considered as a linear filter to which the process identification method is applied. The pulse response of the filter is examined in the pollutant - time plane. The limits of the method and its field of application are discussed. The concept of ergodism and stationariness are introduced. Various diffusion experiments carried out under different conditions are reviewed. Information on the effect of obstacles, and the roughness of the ground is given together with calculations of the longitudinal diffusion and the transport velocity. A brief description is then given of the apparatus used to measure the concentrations and the meteorological conditions. The correlation calculation is also briefly presented. (author)

  11. Characteristics of atmospheric gravity waves observed using the MU (Middle and Upper atmosphere) radar and GPS (Global Positioning System) radio occultation

    OpenAIRE

    Tsuda, Toshitaka

    2014-01-01

    The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10–100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In this paper, we summarize the characteristics of atmospheric gravity waves observed using the middle...

  12. The Thermal Inertia Characteristics of the System Ocean-Atmosphere

    OpenAIRE

    Habibullo I. Abdussamatov; Sergey I. Khankov; Yevgeniy V. Lapovok

    2012-01-01

    To estimate the time delay between the planetary temperature change and the change of the incoming solar radiation fraction absorbed by the ocean and the atmosphere, the analytical energy balance model is presented. The model generalization allows of using averaged data for model parameterization. Using the model, the time delay is investigated on four model cases of absorbed radiation change. The interconnections among the time delay, the planetary thermal inertia and the ocean active layer ...

  13. [Characteristics of atmospheric nitrogen wet deposition in Beijing urban area].

    Science.gov (United States)

    He, Cheng-Wu; Ren, Yu-Fen; Wang, Xiao-Ke; Mao, Yu-Xiang

    2014-02-01

    With the ion-exchange resin method, the atmospheric nitrogen wet deposition in Beijing urban area within the Fifth Ring Road was investigated from June to October, 2012. The relationship between atmospheric nitrogen wet deposition and rainfall precipitation was investigated, the differences of nitrogen wet deposition in different months, different ring roads (the Fifth Ring Road, the Fourth Ring Road, the Third Ring Road and the Second Ring Road) and different functional areas (institutes and colleges district, ring-road, residential areas, railway station and public garden) were also investigated. The results showed that the average value and standard deviation of ammonia-nitrogen, nitrate-nitrogen and nitrite-nitrogen were significantly different during different months in 2012. The atmospheric nitrite nitrogen deposition first decreased and then increased, the maximum value appeared in September. The positive relationships between ammonia nitrogen (nitrate nitrogen) and mean monthly precipitation and negative relationships between nitrite nitrogen and mean monthly precipitation were both significant (P depositions of ring-road and railway station were higher than other functional areas, but only the nitrite nitrogen deposition had obvious regional difference. The differences of the three nitrogen depositions among different ring roads were all not significant and it meant that the nitrogen wet deposition was equally distributed in Beijing urban area. PMID:24812938

  14. MIMO Free-Space Optical Communication Employing Subcarrier Intensity Modulation in Atmospheric Turbulence Channels

    Science.gov (United States)

    Ghassemlooy, Zabih; Popoola, Wasiu O.; Ahmadi, Vahid; Leitgeb, Erich

    In this paper, we analyse the error performance of transmitter/receiver array free-space optical (FSO) communication system employing binary phase shift keying (BPSK) subcarrier intensity modulation (SIM) in clear but turbulent atmospheric channel. Subcarrier modulation is employed to eliminate the need for adaptive threshold detector. Direct detection is employed at the receiver and each subcarrier is subsequently demodulated coherently. The effect of irradiance fading is mitigated with an array of lasers and photodetectors. The received signals are linearly combined using the optimal maximum ratio combining (MRC), the equal gain combining (EGC) and the selection combining (SelC). The bit error rate (BER) equations are derived considering additive white Gaussian noise and log normal intensity fluctuations. This work is part of the EU COST actions and EU projects.

  15. Development and characterization of the superconducting integrated receiver channel of the TELIS atmospheric sounder

    International Nuclear Information System (INIS)

    The balloon-borne instrument TELIS (TErahertz and submillimetre LImb Sounder) is a three-channel superconducting heterodyne spectrometer for atmospheric research use. It detects spectral emission lines of stratospheric trace gases that have their rotational transitions at THz frequencies. One of the channels is based on the superconducting integrated receiver (SIR) technology. We demonstrate for the first time the capabilities of the SIR technology for heterodyne spectroscopy in general, and atmospheric limb sounding in particular. We also show that the application of SIR technology is not limited to laboratory environments, but that it is well suited for remote operation under harsh environmental conditions. Within a SIR the main components needed for a superconducting heterodyne receiver such as a superconductor-insulator-superconductor (SIS) mixer with a quasi-optical antenna, a flux-flow oscillator (FFO) as the local oscillator, and a harmonic mixer to phase lock the FFO are integrated on a single chip. Light weight and low power consumption combined with broadband operation and nearly quantum limited sensitivity make the SIR a perfect candidate for use in future airborne and space-borne missions. The noise temperature of the SIR was measured to be as low as 120 K, with an intermediate frequency band of 4-8 GHz in double-sideband operation. The spectral resolution is well below 1 MHz, confirmed by our measurements. Remote control of the SIR under flight conditions has been demonstrated in a successful balloon flight in Kiruna, Sweden. The sensor and instrument design are presented, as well as the preliminary science results from the first flight.

  16. Development and characterization of the superconducting integrated receiver channel of the TELIS atmospheric sounder

    Science.gov (United States)

    de Lange, Gert; Birk, Manfred; Boersma, Dick; Dercksen, Johannes; Dmitriev, Pavel; Ermakov, Andrey B.; Filippenko, Lyudmila V.; Golstein, Hans; Hoogeveen, Ruud W. M.; de Jong, Leo; Khudchenko, Andrey V.; Kinev, Nickolay V.; Kiselev, Oleg S.; van Kuik, Bart; de Lange, Arno; van Rantwijk, Joris; Selig, Avri M.; Sobolev, Alexander S.; Torgashin, Mikhail Yu; de Vries, Ed; Wagner, Georg; Yagoubov, Pavel A.; Koshelets, Valery P.

    2010-04-01

    The balloon-borne instrument TELIS (TErahertz and submillimetre LImb Sounder) is a three-channel superconducting heterodyne spectrometer for atmospheric research use. It detects spectral emission lines of stratospheric trace gases that have their rotational transitions at THz frequencies. One of the channels is based on the superconducting integrated receiver (SIR) technology. We demonstrate for the first time the capabilities of the SIR technology for heterodyne spectroscopy in general, and atmospheric limb sounding in particular. We also show that the application of SIR technology is not limited to laboratory environments, but that it is well suited for remote operation under harsh environmental conditions. Within a SIR the main components needed for a superconducting heterodyne receiver such as a superconductor-insulator-superconductor (SIS) mixer with a quasi-optical antenna, a flux-flow oscillator (FFO) as the local oscillator, and a harmonic mixer to phase lock the FFO are integrated on a single chip. Light weight and low power consumption combined with broadband operation and nearly quantum limited sensitivity make the SIR a perfect candidate for use in future airborne and space-borne missions. The noise temperature of the SIR was measured to be as low as 120 K, with an intermediate frequency band of 4-8 GHz in double-sideband operation. The spectral resolution is well below 1 MHz, confirmed by our measurements. Remote control of the SIR under flight conditions has been demonstrated in a successful balloon flight in Kiruna, Sweden. The sensor and instrument design are presented, as well as the preliminary science results from the first flight.

  17. Pressure drop characteristic of flow boiling in narrow rectangular channel under rolling motion

    International Nuclear Information System (INIS)

    Experimental investigation and analysis of the pressure drop characteristic of flow boiling in narrow rectangular channel were conducted under rolling motion. Several correlations for the two-phase frictional pressure drop were evaluated against the experimental data. The results show that the correlations for conventional channel poorly predict the results. While the Zhang-Mishima and Sun-Mishima correlations developed for narrow channel are better than other correlations. On the other hand, the pressure drop characteristic of flow boiling was analyzed under rolling motion. The two-phase pressure drop changes cyclically due to the rolling motion, rolling angle and period almost have no effect on the fluctuation of pressure drop and the average two-phase frictional pressure drop. (authors)

  18. An investigation of 'sparse channel networks'. Characteristic behaviours and their causes

    International Nuclear Information System (INIS)

    This report represents a third study in a series concerned with groundwater flow in poorly permeable fractured crystalline rocks. The study has brought together three linked, but distinct, elements; a mathematical analysis of the intersection of ellipses, a review of field measurements associated with nuclear waste repository investigations and probabilistic simulations using a lattice network numerical model. We conclude that the model of channels that traverse fracture intersections without necessarily branching is a very likely representation of reality. More generally, assembling all the lines of evidence, it is suggested that groundwater flow systems in fractured crystalline rocks in the environs of underground laboratories have the following characteristics: Groundwater flows within a sparse network of channels just above the percolation limit. The frequency of intersections is low in that individual channels extend considerable distances between significant junctions. Individual channels often extend over many fracture surfaces and the resulting flow system is only weakly related to the density or size of mappable fractures. The sparseness of systems compared to the size of drifts and tunnels means that only a very few flow channels are intersected by drifts and tunnels. Highly convergent flow is required to connect to the rest of the network and this is misinterpreted as a skin of low hydraulic conductivity. Systems are so sparse that they are controlled by a few 'chokes' that give rise to compartments of head, and probably, of groundwater chemistry. Channels occur on all fracture planes, including those within fracture zones, and although the characteristics of the fracture zone channel networks may differ from those in surrounding rocks, they are nonetheless still channel networks. The actively flowing sparse channel network, occurring within any particular rock, is a naturally selected, small sub-set of the available channels. Hence, there are many

  19. An investigation of 'sparse channel networks'. Characteristic behaviours and their causes

    Energy Technology Data Exchange (ETDEWEB)

    Black, J.H. (In Situ Solutions, East Bridgford (GB)); Barker, J.A.; Woodman, N.D. (Univ. of Southampton (GB))

    2007-09-15

    This report represents a third study in a series concerned with groundwater flow in poorly permeable fractured crystalline rocks. The study has brought together three linked, but distinct, elements; a mathematical analysis of the intersection of ellipses, a review of field measurements associated with nuclear waste repository investigations and probabilistic simulations using a lattice network numerical model. We conclude that the model of channels that traverse fracture intersections without necessarily branching is a very likely representation of reality. More generally, assembling all the lines of evidence, it is suggested that groundwater flow systems in fractured crystalline rocks in the environs of underground laboratories have the following characteristics: Groundwater flows within a sparse network of channels just above the percolation limit. The frequency of intersections is low in that individual channels extend considerable distances between significant junctions. Individual channels often extend over many fracture surfaces and the resulting flow system is only weakly related to the density or size of mappable fractures. The sparseness of systems compared to the size of drifts and tunnels means that only a very few flow channels are intersected by drifts and tunnels. Highly convergent flow is required to connect to the rest of the network and this is misinterpreted as a skin of low hydraulic conductivity. Systems are so sparse that they are controlled by a few 'chokes' that give rise to compartments of head, and probably, of groundwater chemistry. Channels occur on all fracture planes, including those within fracture zones, and although the characteristics of the fracture zone channel networks may differ from those in surrounding rocks, they are nonetheless still channel networks. The actively flowing sparse channel network, occurring within any particular rock, is a naturally selected, small sub-set of the available channels. Hence, there are

  20. Thermalhydraulic characteristics for fuel channels using burnable poison in the CANDU reactor

    International Nuclear Information System (INIS)

    The power coefficient is one of the most important physics parameters governing nuclear reactor safety and operational stability, and its sign and magnitude have a significant effect on the safety and control characteristics of the power reactor. Recently, for an equilibrium CANDU core, the power coefficient was reported to be slightly positive when newly developed Industry Standard Tool set reactor physics codes were used. Therefore, it is required to find a new way to effectively decrease the positive power coefficient of CANDU reactor without seriously compromising the economy. In order to make the power coefficient of the CANDU reactor negative at the operating power, Roh et al. have evaluated the various burnable poison (BP) materials and its loading scheme in terms of the fuel performance and reactor safety characteristics. It was shown that reactor safety characteristics can be greatly improved by the use of the BP in the CANDU reactor. However, the previous study has mainly focused on the safety characteristics by evaluating the power coefficient for the fuel channel using BP in the CANDU reactor. Together with the safety characteristics, the economic performance is also important in order to apply the newly designed fuel channel to the power plant. In this study, the economic performance has been evaluated by analyzing the thermal hydraulic characteristics for the fuel channel using BP in the CANDU reactor

  1. Thermal-hydraulic characteristics of the RBMK control and protection system channels

    International Nuclear Information System (INIS)

    The thermal-hydraulic characteristics of the RBMK-1000 control and protection system channel with rod cluster control have been calculated under different operational disturbance regimes. It has been shown that the temperature of the rod cluster control structural materials increases considerably if loss of coolant occurs. The critical element is the sleeve made of CAB1 aluminum alloy

  2. Analysis of channel with special heat transfer characteristics for cooling nuclear reactor fuel elements

    International Nuclear Information System (INIS)

    Improvement of heat transfer characteristics of nuclear reactor cooling channels is analysed. A generalization of the Ambrok solution for the energy integral equation is proposed. A new improved passage shape is determined. Theoretical results are compared with experimental data. The agreement is excellent. (author)

  3. Changes in Atmospheric Sulfur Dioxide (SO2) over the English Channel - 1.5 Years of Measurements from the Penlee Point Atmospheric Observatory

    Science.gov (United States)

    Yang, Mingxi; Bell, Thomas; Hopkins, Frances; Smyth, Timothy

    2016-04-01

    Atmospheric sulfur dioxide (SO2) was measured continuously from the Penlee Point Atmospheric Observatory near Plymouth, United Kingdom between May 2014 and November 2015. This coastal site is exposed to marine air across a wide wind sector. The predominant southwesterly winds carry relatively clean background Atlantic air. In contrast, air from the southeast is heavily influenced by exhaust plumes from ships in the English Channel as well as near near the Plymouth Sound. International Maritime Organization regulation came into force in January 2015 to reduce sulfur emissions tenfold in Sulfur Emission Control Areas such as the English Channel. We observed a three-fold reduction from 2014 to 2015 in the estimated ship-emitted SO2 during southeasterly winds. Dimethylsulfide (DMS) is an important source of atmospheric SO2 even in this semi-polluted region. The relative contribution of DMS oxidation to the SO2 burden over the English Channel increased from ~1/3 in 2014 to ~1/2 in 2015 due to the reduction in ship sulfur emissions. Our diel analysis suggests that SO2 is removed from the marine atmospheric boundary layer in about half a day, with dry deposition to the ocean accounting for a quarter of the total loss.

  4. Communication systems, transceivers, and methods for generating data based on channel characteristics

    Science.gov (United States)

    Forman, Michael A; Young, Derek

    2012-09-18

    Examples of methods for generating data based on a communications channel are described. In one such example, a processing unit may generate a first vector representation based in part on at least two characteristics of a communications channel. A constellation having at least two dimensions may be addressed with the first vector representation to identify a first symbol associated with the first vector representation. The constellation represents a plurality of regions, each region associated with a respective symbol. The symbol may be used to generate data, which may stored in an electronic storage medium and used as a cryptographic key or a spreading code or hopping sequence in a modulation technique.

  5. Characteristics of crosstalk in the reproduced output of a newly developed multi-channel MR head

    International Nuclear Information System (INIS)

    We prepared the multi-channel magnetoresistive head with a simple structural design and it has the advantages of high-density recording and ultra-high transfer rate. Characteristics of crosstalk in the reproduced output of our head have been estimated by a micromagnetic calculation using the Landau-Lifshitz-Gilbert (LLG) equation, while the specimen head was fabricated and evaluated. As a result, by applying a magnetic field of 40 Oe only between adjacent channels, the crosstalk was much decreased without reducing the reproduced output

  6. Interactions Between Channel Topography and Hydrokinetic Turbines: Sediment Transport, Turbine Performance, and Wake Characteristics

    Science.gov (United States)

    Hill, Craig Steven

    Accelerating marine hydrokinetic (MHK) renewable energy development towards commercial viability requires investigating interactions between the engineered environment and its surrounding physical and biological environments. Complex and energetic hydrodynamic and morphodynamic environments desired for such energy conversion installations present difficulties for designing efficient yet robust sustainable devices, while permitting agency uncertainties regarding MHK device environmental interactions result in lengthy and costly processes prior to installing and demonstrating emerging technologies. A research program at St. Anthony Falls Laboratory (SAFL), University of Minnesota, utilized multi-scale physical experiments to study the interactions between axial-flow hydrokinetic turbines, turbulent open channel flow, sediment transport, turbulent turbine wakes, and complex hydro-morphodynamic processes in channels. Model axial-flow current-driven three-bladed turbines (rotor diameters, dT = 0.15m and 0.5m) were installed in open channel flumes with both erodible and non-erodible substrates. Device-induced local scour was monitored over several hydraulic conditions and material sizes. Synchronous velocity, bed elevation and turbine performance measurements provide an indication into the effect channel topography has on device performance. Complimentary experiments were performed in a realistic meandering outdoor research channel with active sediment transport to investigate device interactions with bedform migration and secondary turbulent flow patterns in asymmetric channel environments. The suite of experiments undertaken during this research program at SAFL in multiple channels with stationary and mobile substrates under a variety of turbine configurations provides an in-depth investigation into how axial-flow hydrokinetic devices respond to turbulent channel flow and topographic complexity, and how they impact local and far-field sediment transport characteristics

  7. ON SOME PROPAGATION CHARACTERISTICS OF TROPICAL ATMOSPHERIC AND COSMIC RADIO NOISE

    Directory of Open Access Journals (Sweden)

    A.B.BHATTACHARYA

    2011-07-01

    Full Text Available Sources responsible for generating noise in the magnetospheric and ionospheric cavities with reference to the relative power levels in different frequency bands are examined. Some propagation characteristics of both atmospheric and cosmic radio noise as recorded at Kalyani have been examined. The characteristics obtained are compared with other reported results.

  8. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    Science.gov (United States)

    Zhang, Hao; Zhu, Fengsen; Tu, Xin; Bo, Zheng; Cen, Kefa; Li, Xiaodong

    2016-05-01

    In this work, a novel direct current (DC) atmospheric pressure rotating gliding arc (RGA) plasma reactor has been developed for plasma-assisted chemical reactions. The influence of the gas composition and the gas flow rate on the arc dynamic behaviour and the formation of reactive species in the N2 and air gliding arc plasmas has been investigated by means of electrical signals, high speed photography, and optical emission spectroscopic diagnostics. Compared to conventional gliding arc reactors with knife-shaped electrodes which generally require a high flow rate (e.g., 10–20 L/min) to maintain a long arc length and reasonable plasma discharge zone, in this RGA system, a lower gas flow rate (e.g., 2 L/min) can also generate a larger effective plasma reaction zone with a longer arc length for chemical reactions. Two different motion patterns can be clearly observed in the N2 and air RGA plasmas. The time-resolved arc voltage signals show that three different arc dynamic modes, the arc restrike mode, takeover mode, and combined modes, can be clearly identified in the RGA plasmas. The occurrence of different motion and arc dynamic modes is strongly dependent on the composition of the working gas and gas flow rate. supported by National Natural Science Foundation of China (No. 51576174), the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20120101110099) and the Fundamental Research Funds for the Central Universities (No. 2015FZA4011)

  9. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hao; ZHU Fengsen; TU Xin; BO Zheng; CEN Kefa; LI Xiaodong

    2016-01-01

    In this work,a novel direct current (DC) atmospheric pressure rotating gliding arc (RGA) plasma reactor has been developed for plasma-assisted chemical reactions.The influence of the gas composition and the gas flow rate on the arc dynamic behaviour and the formation of reactive species in the N2 and air gliding arc plasmas has been investigated by means of electrical signals,high speed photography,and optical emission spectroscopic diagnostics.Compared to conventional gliding arc reactors with knife-shaped electrodes which generally require a high flow rate (e.g.,10-20 L/min) to maintain a long arc length and reasonable plasma discharge zone,in this RGA system,a lower gas flow rate (e.g.,2 L/min) can also generate a larger effective plasma reaction zone with a longer arc length for chemical reactions.Two different motion patterns can be clearly observed in the N2 and air RGA plasmas.The time-resolved arc voltage signals show that three different arc dynamic modes,the arc restrike mode,takeover mode,and combined modes,can be clearly identified in the RGA plasmas.The occurrence of different motion and arc dynamic modes is strongly dependent on the composition of the working gas and gas flow rate.

  10. Characteristics of dielectric barrier discharge plasmas in atmospheric humid air

    Science.gov (United States)

    Fukuda, Y.; Fukui, K.; Iwami, R.; Matsuoka, Y.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    Atmospheric pressure plasmas have a great advantage for industrial applications such as surface modifications, sterilization and film preparation. In particular, reactive plasmas including OH radicals can be generated in humid air. On the other hand, it is known that dielectric barrier discharge (DBD) plasmas in air are strongly affected by humidity. In this study, a twisted pair sample is used as a DBD electrode. The twisted pair consists of two enameled wires, and it is installed in a climate chamber to control ambient temperature and humidity. Repetitive impulse voltage pulses were applied to the twisted pair to produce DBD plasmas. Light emission, electromagnetic wave and current pulses were used to detect discharge activities. The discharge inception voltage (DIV) is basically determined by Paschen curve in air, however, the DIV was decreased by increasing the humidity. In addition, it was found that there were largely scattered data of DIV at the low humidity condition. After the pre-discharges, the DIV reached to the steady state value. On the other hand, there was no scattering of the observed DIV at the high humidity condition. Measurements of surface potential of the sample after the discharge show these behaviors could be explained by surface charge accumulation on the enameled wire. It is noted that there was no fluctuation in the DIV data in the case of unipolar voltage pulse.

  11. Study on target characteristic polarization state in co-polarized channel for the coherent case

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The target characteristic polarization state in the co-polarized channel for the coherent case was studied in greater detail, with emphasis on the analysis of the characteristic polarization states variable with the target parameters. The Sinclair backscatter matrix was diagonalized under the change of polariza- tion basis via a unitary transformation matrix. Then the diagonal matrix was parameterized by four parameters viz. matrix amplitude, absolute phase, amplitude ratio and phase difference. The behavior of the characteristic polarization states with the varieties of target parameters was discussed together with the power density plot. The characteristic polarization states were displayed on the Poincare sphere and six conclusions were obtained, which provide theoretic support for decreasing the computational complexity of target characteristic polarization state, or anticipating its position in the power density plot. Several simple target cases were considered for validating these conclusions.

  12. Performance analysis of 2D asynchronous hard-limiting optical code-division multiple access system through atmospheric scattering channel

    Science.gov (United States)

    Zhao, Yaqin; Zhong, Xin; Wu, Di; Zhang, Ye; Ren, Guanghui; Wu, Zhilu

    2013-09-01

    Optical code-division multiple access (OCDMA) systems usually allocate orthogonal or quasi-orthogonal codes to the active users. When transmitting through atmospheric scattering channel, the coding pulses are broadened and the orthogonality of the codes is worsened. In truly asynchronous case, namely both the chips and the bits are asynchronous among each active user, the pulse broadening affects the system performance a lot. In this paper, we evaluate the performance of a 2D asynchronous hard-limiting wireless OCDMA system through atmospheric scattering channel. The probability density function of multiple access interference in truly asynchronous case is given. The bit error rate decreases as the ratio of the chip period to the root mean square delay spread increases and the channel limits the bit rate to different levels when the chip period varies.

  13. Fading Characteristics of Wireless Channel on High-Speed Railway in Hilly Terrain Scenario

    Directory of Open Access Journals (Sweden)

    Fengyu Luan

    2013-01-01

    Full Text Available This paper focuses on the fading characteristics of wireless channel on High-Speed Railway (HSR in hilly terrain scenario. Due to the rapid speed, the fading characteristics of HSR channel are highly correlated with time or Transmit-Receive distance and have their own special property. To investigate the fading characteristics, the measurement is conducted on the Guangzhou-Shenzhen passenger-dedicated line in China with the speed of 295 km/h in the data-collection area at 2.4 GHz. From the measured data, the amplitude of each path is estimated by using the Subspace-Alternating Generalized Expectation-Maximization (SAGE algorithm along with other parameters of channel impulse responses. Then the fading parameters, including path loss, shadow fading, and K-factor, are analysed. With the numerical results in the measurement and analysis, the fading characteristics have been revealed and modelled. It is supposed that this work has a promotion for HSR communication system design and improvement.

  14. Atmospheric pressure ionization waves propagating through a flexible high aspect ratio capillary channel and impinging upon a target

    International Nuclear Information System (INIS)

    Atmospheric pressure ionization waves (IWs) propagating in flexible capillary tubes are a unique way of transporting a plasma and its active species to remote sites for applications such as biomedical procedures, particularly in endoscopic procedures. The propagation mechanisms for such IWs in tubes having aspect ratios of hundreds to thousands are not clear. In this paper, results are discussed from a numerical investigation of the fundamental properties of ionization waves generated by nanosecond voltage pulses inside a 15 cm long, 600 µm wide (aspect ratio 250), flexible dielectric channel. The channel, filled with a Ne/Xe = 99.9/0.1 gas mixture at 1 atm, empties into a small chamber separated from a target substrate by 1 cm. The IWs propagate through the entire length of the channel while maintaining similar strength and magnitude. Upon exiting the channel into the chamber, the IW induces a second streamer discharge at the channel–chamber junction. This streamer then propagates across the chamber and impinges upon the target. The average speeds of the capillary-bounded IW are about 5 × 107 cm s−1 and 1 × 108 cm s−1 for positive and negative polarities, respectively. The propagation speed is sensitive to the curvature of the channel. In both cases, the peak in ionization tends to be located along the channel walls and alternates from side-to-side depending on the direction of the local instantaneous electric field and curvature of the channel. The ionization region following the IW extends up to several centimeters inside the channel, as opposed to being highly localized at the ionization front in unconstrained, atmospheric pressure IWs. The maximum speed of the IW in the chamber is about twice that in the channel. (paper)

  15. Atmospheric correction for sea surface temperature retrieval from single thermal channel radiometer data onboard Kalpana satellite

    Indian Academy of Sciences (India)

    Naveen R Shahi; Neeraj Agarwal; Aloke K Mathur; Abhijit Sarkar

    2011-06-01

    An atmospheric correction method has been applied on sea surface temperature (SST) retrieval algorithm using Very High Resolution Radiometer (VHRR) single window channel radiance data onboard Kalpana satellite (K-SAT). The technique makes use of concurrent water vapour fields available from Microwave Imager onboard Tropical Rainfall Measuring Mission (TRMM/TMI) satellite. Total water vapour content and satellite zenith angle dependent SST retrieval algorithm has been developed using Radiative Transfer Model [MODTRAN ver3.0] simulations for Kalpana 10.5–12.5 m thermal window channel. Retrieval of Kalpana SST (K-SST) has been carried out for every half-hourly acquisition of Kalpana data for the year 2008 to cover whole annual cycle of SST over Indian Ocean (IO). Validation of the retrieved corrected SST has been carried out using near-simultaneous observations of ship and buoys datasets covering Arabian Sea, Bay of Bengal and IO regions. A significant improvement in Root Mean Square Deviation (RMSD) of K-SST with respect to buoy (1.50–1.02 K) and to ship datasets (1.41–1.19 K) is seen with the use of near real-time water vapour fields of TMI. Furthermore, comparison of the retrieved SST has also been carried out using near simultaneous observations of TRMM/TMI SST over IO regions. The analysis shows that K-SST has overall cold bias of 1.17 K and an RMSD of 1.09 K after bias correction.

  16. Thermal characteristics of condensing steam in a single horizontal mini-channel with triangular shape

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jae Hee; Hwang, Kyo Sik; Ha, Hyo Jun; Jang, Seok Pil [Korea Aerospace Univ., Goyang (Korea, Republic of); Lee, Ki Woo [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2009-07-01

    In the papermaking processes it is well known that the dryer uses the largest amount of energy and has costly components compared with other devices. Many researchers thus conducted to reduce energy and cost of the dryer. Recently Argonne national laboratory has developed the concept of a multiport cylinder dryer that the steam flows along longitudinally oriented mini-channels which are close to inner surface of cylinder dryer. They reported that the innovative design minimizes the condensate layer thickness. However, systematically experimental data are not available. So in this paper we will conduct experiments to study thermal characteristics of condensing steam in a single horizontal mini-channel with triangular shape, representative of a multiport cylinder dryer. Based on the results, we confirm previous results and observe the condensing heat transfer coefficient in the single horizontal mini-channel with triangular shape.

  17. Thermal characteristics of condensing steam in a single horizontal mini-channel with triangular shape

    International Nuclear Information System (INIS)

    In the papermaking processes it is well known that the dryer uses the largest amount of energy and has costly components compared with other devices. Many researchers thus conducted to reduce energy and cost of the dryer. Recently Argonne national laboratory has developed the concept of a multiport cylinder dryer that the steam flows along longitudinally oriented mini-channels which are close to inner surface of cylinder dryer. They reported that the innovative design minimizes the condensate layer thickness. However, systematically experimental data are not available. So in this paper we will conduct experiments to study thermal characteristics of condensing steam in a single horizontal mini-channel with triangular shape, representative of a multiport cylinder dryer. Based on the results, we confirm previous results and observe the condensing heat transfer coefficient in the single horizontal mini-channel with triangular shape.

  18. Dispersion characteristics of the electromagnetic waves in a relativistic electron beam guided by the ion channel

    International Nuclear Information System (INIS)

    In this article, the dispersion characteristics of the paraxial (near axis) electromagnetic (EM) waves in a relativistic electron beam guided by the ion channel are investigated. Equilibrium fields such as ion-channel electrostatic field and self-fields of relativistic electron beam are included in this formalism. In accordance with the equilibrium field structure, radial and azimuthal waves are selected as base vectors for EM waves. It is shown that the dispersion of the radially polarized EM and space charge waves are influenced by the equilibrium fields, but azimuthally polarized wave remain unaffected. In some wave number domains, the radially polarized EM and fast space charge waves are coupled. In these regions, instability is analyzed as a function of equilibrium structure. It is shown that the total equilibrium radial force due to the ion channel and electron beam and also relativistic effect play a key role in the coupling of the radially polarized EM wave and space charge wave. Furthermore, some asymptotic behaviors such as weak and strong ion channel, nonrelativistic case and cutoff frequencies are discussed. This instability could be used as an amplification mechanism for radially polarized EM waves in a beam-plasma system where a relativistic electron beam is guided by the ion channel.

  19. Inversion channel diamond metal-oxide-semiconductor field-effect transistor with normally off characteristics.

    Science.gov (United States)

    Matsumoto, Tsubasa; Kato, Hiromitsu; Oyama, Kazuhiro; Makino, Toshiharu; Ogura, Masahiko; Takeuchi, Daisuke; Inokuma, Takao; Tokuda, Norio; Yamasaki, Satoshi

    2016-01-01

    We fabricated inversion channel diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with normally off characteristics. At present, Si MOSFETs and insulated gate bipolar transistors (IGBTs) with inversion channels are widely used because of their high controllability of electric power and high tolerance. Although a diamond semiconductor is considered to be a material with a strong potential for application in next-generation power devices, diamond MOSFETs with an inversion channel have not yet been reported. We precisely controlled the MOS interface for diamond by wet annealing and fabricated p-channel and planar-type MOSFETs with phosphorus-doped n-type body on diamond (111) substrate. The gate oxide of Al2O3 was deposited onto the n-type diamond body by atomic layer deposition at 300 °C. The drain current was controlled by the negative gate voltage, indicating that an inversion channel with a p-type character was formed at a high-quality n-type diamond body/Al2O3 interface. The maximum drain current density and the field-effect mobility of a diamond MOSFET with a gate electrode length of 5 μm were 1.6 mA/mm and 8.0 cm(2)/Vs, respectively, at room temperature. PMID:27545201

  20. Period-two discharge characteristics in argon atmospheric dielectric-barrier discharges

    International Nuclear Information System (INIS)

    Period multiplication and chaos behaviors in atmospheric glow discharges are important to understand atmospheric glow plasma stability and to optimize its applications. In this paper, we study the period-two discharge characteristics in argon atmospheric dielectric-barrier discharges using a one-dimension fluid model. Under certain conditions, period-two discharges can occur at different excitation frequencies and exhibit different current and voltage behaviors. When the discharge current becomes highly symmetrical the period-two discharge can reach to a steady state, which sustains over a broad frequency range. At the sufficiently high excitation frequency, the period-two discharge in atmospheric argon shows noticeably different behaviors from the discharges generated at kilohertz frequency. The spatial characteristics of period-two discharge as well as the influence of driving frequency on period-two discharge behaviors are also investigated.

  1. Modeling efforts to improve the Asian Summer Monsoon representation in a coupled ocean-atmosphere tropical-channel model

    Science.gov (United States)

    Samson, G.; Masson, S. G.; Durand, F.; Terray, P.; Berthet, S.; Jullien, S.

    2015-12-01

    The Asian Summer Monsoon (ASM) simulated over the 1989-2009 period with a new 0.75° coupled ocean-atmosphere tropical-channel (45°S-45°N) model based on WRF and NEMO models is presented. The model biases are comparable to those commonly found in coupled global coupled models (CGCMs): the Findlater jet is too weak, precipitations are underestimated over India while they are overestimated over South-East Asia and the Maritime Continent. The ASM onset is delayed by several weeks, an error which is also very common in current CGCMs. We show that land surface temperature errors are a major source of the ASM low-level circulation and rainfall biases in our model: a cold bias over the Middle-East region weakens the Findlater jet while a warm bias over India strengthens the monsoon circulation in the Bay of Bengal. To explore the origins of those biases and their relationship with the ASM, a series of sensitivity experiments is presented. First, we show that changing the land surface albedo representation in our model directly influences the ASM characteristics by reducing the cold bias in the Middle-East region. It improves the "heat low" representation, which has direct implication on the Findlater jet strength and precipitation over India. Furthermore, the ASM onset is shifted back by almost one month in agreement with observations. Second, a parameterization of the convective cloud-radiative feedback is introduced in the atmospheric model. It acts to reduce the warm bias present in convective regions such as India and favors the monsoon northward migration. As a consequence, the dry bias is reduced in this region. Finally, horizontal resolution is increased from 0.75° to 0.25° for both oceanic and atmospheric models to assess the sensitivity of the ASM biases to the model resolution. Large-scale model errors persist at higher resolution, but are significantly attenuated. Precipitation is improved in mountainous areas with strong orographic control, but also in

  2. Effect of Atmosphere on Volatile Emission Characteristic in Oxy-Fuel Combustion

    OpenAIRE

    Jia Luo; Shihe Chen; Le Wu

    2013-01-01

    A new type of power supply which was called oxy-fuel combustion power plant was introduced to reduce greenhouse gasses emission. In this paper the volatile emission characteristic of pulverized coal is studied under air atmosphere and oxy-fuel atmosphere. Combustion experiments of Datong bituminous coal were carried out in a wire mesh reactor at heating rates of 1 K/s, 10 K/s and 1000 K/s respectively under air and O2/CO2 atmosphere conditions in order to investigate the volatile emission ch...

  3. Thermal-hydraulic characteristics and performance of 3D wavy channel based printed circuit heat exchanger

    International Nuclear Information System (INIS)

    CFD study is done here to propose an efficient PCHE (Printed Circuit Heat Exchanger) model; used as a recuperator in International Thermonuclear Experimental Reactor (ITER). 3D steady state conjugate heat-transfer numerical simulations are done; considering the variation of thermo-physical properties as a function of temperature. Helium is used as a working fluid and alloy 617 as solid substrate. The study is done for various angle of bend (θ = 0°(straight), 5°, 10° and 15°) and Reynolds number (Re = 350, 700, 1400 and 2100). Various types of flow patterns, within one wavy-section, are presented to analyze thermal-hydraulic characteristics. Thermal hydraulic performance parameters are presented for the various wavy-sections as well as within a section; and for the complete PCHE model. Heat transfer enhancement as compared to pressure penalty is higher for the wavy channel; and increases with increasing Re and θ. Wavy as compared to plane channel based PCHE is demonstrated here to give better thermal-hydraulic performance. A detailed characteristics as well as performance-parameters for thermal hydraulics in a 3D wavy channel based PCHE model − not found in the literature − is presented here. - Highlights: • Studied effect of Reynolds number and angle of bend. • Analyzed thermal-hydraulic characteristics, by various types of flow pat-terns. • Demonstrated an increase in local heat flux due to change in the flow-direction. • Demonstrated better performance of wavy as compared to plane channel based PCHE. • Proposed correlation for friction factor and Nusselt number

  4. ANALYSIS ON CHARACTERISTICS OF ATMOSPHERIC DUCT AND ITS EFFECTS ON THE PROPAGATION OF ELECTROMAGNETIC WAVE

    Institute of Scientific and Technical Information of China (English)

    姚展予; 赵柏林; 李万彪; 朱元竞; 杜金林; 戴福山

    2001-01-01

    On the basis of introducing the basic categories of atmospheric refraction and their existing conditions, the forming processes of three kinds of atmospheric duets are expounded. Several main characteristics of atmospheric duct are summarized and analyzed, and field sounding data from the WEstern North-Pacific cloud-radiation EXperiment (WENPEX) and meteorological data around the Xisha sea area are used to validate these characteristics. Meanwhile the sensitivities of the evaporation duct height to the variations of atmospheric humidity, the air-sea temperature difference, and horizontal wind speed are examined. With the analysis of the effect of atmospheric duct on the propagation of electromagnetic wave, the maximum trapped-wavelength and the critical emitting angle of elevation for electromagnetic wave which can form duct propagation are derived.At the same time the four kinds of necessary conditions for electromagnetic wave to form duct propagation are brought forward. The effects of atmospheric duct on ultrashort wave propagation,radar observation, short wave communication etc. are also discussed.

  5. Target-in-the-loop remote sensing of laser beam and atmospheric turbulence characteristics.

    Science.gov (United States)

    Vorontsov, Mikhail A; Lachinova, Svetlana L; Majumdar, Arun K

    2016-07-01

    A new target-in-the-loop (TIL) atmospheric sensing concept for in situ remote measurements of major laser beam characteristics and atmospheric turbulence parameters is proposed and analyzed numerically. The technique is based on utilization of an integral relationship between complex amplitudes of the counterpropagating optical waves known as overlapping integral or interference metric, whose value is preserved along the propagation path. It is shown that the interference metric can be directly measured using the proposed TIL sensing system composed of a single-mode fiber-based optical transceiver and a remotely located retro-target. The measured signal allows retrieval of key beam and atmospheric turbulence characteristics including scintillation index and the path-integrated refractive index structure parameter. PMID:27409206

  6. An adaptation method to improve secret key rates of time-frequency QKD in atmospheric turbulence channels

    Science.gov (United States)

    Sun, Xiaole; Djordjevic, Ivan B.; Neifeld, Mark A.

    2016-03-01

    Free-space optical (FSO) channels can be characterized by random power fluctuations due to atmospheric turbulence, which is known as scintillation. Weak coherent source based FSO quantum key distribution (QKD) systems suffer from the scintillation effect because during the deep channel fading the expected detection rate drops, which then gives an eavesdropper opportunity to get additional information about protocol by performing photon number splitting (PNS) attack and blocking single-photon pulses without changing QBER. To overcome this problem, in this paper, we study a large-alphabet QKD protocol, which is achieved by using pulse-position modulation (PPM)-like approach that utilizes the time-frequency uncertainty relation of the weak coherent photon state, called here TF-PPM-QKD protocol. We first complete finite size analysis for TF-PPM-QKD protocol to give practical bounds against non-negligible statistical fluctuation due to finite resources in practical implementations. The impact of scintillation under strong atmospheric turbulence regime is studied then. To overcome the secure key rate performance degradation of TF-PPM-QKD caused by scintillation, we propose an adaptation method for compensating the scintillation impact. By changing source intensity according to the channel state information (CSI), obtained by classical channel, the adaptation method improves the performance of QKD system with respect to the secret key rate. The CSI of a time-varying channel can be predicted using stochastic models, such as autoregressive (AR) models. Based on the channel state predictions, we change the source intensity to the optimal value to achieve a higher secret key rate. We demonstrate that the improvement of the adaptation method is dependent on the prediction accuracy.

  7. Flight characteristics of probes in the atmospheres of Mars, Venus, and the outer planets

    Science.gov (United States)

    Intrieri, P. F.; Derose, C. E.; Kirk, D. B.

    1976-01-01

    Density, pressure, and temperature profiles of an unknown planetary atmosphere can be obtained from the high-speed entry of a probe provided the aerodynamic characteristics of the probe in this atmosphere are accurately known. An investigation of the effect of gas composition on probe aerodynamics has been conducted in the Ames Hypersonic Free Flight Facility by gun launching small-scale models into atmospheres representative of Mars, Venus, Jupiter, and Saturn. Aerodynamic data at conditions matching the velocity and Reynolds number at a number of points on the Viking trajectory (Mars) were obtained in both air and carbon dioxide and significant differences were noted. Aerodynamic data are also presented from tests in hydrogen and hydrogen-helium mixtures, gases which characterize the atmospheres of the outer planets.

  8. The characteristics of secondary flows in compound channels with vegetated floodplains

    Institute of Scientific and Technical Information of China (English)

    LIU Chao; SHAN Yu-qi; YANG Ke-jun; LIU Xing-nian

    2013-01-01

    The experiments were conducted in compound channels with vegetated floodplains for investigating the influence of vegetation types on the characteristics of secondary flows.In terms of the streamwise and transverse velocities and the depth-averaged velocity,the secondary flow coefficient,M,is proposed,with good physical meanings,and it may characterize the rotational direction and the intensity of the secondary currents.The experimental results show that,for the cases without vegetation and with grass,the rotational directions of the secondary flows are all anticlockwise while for the cases with shrubs,they are all changed to the clockwise direction in the whole cross-section.However,when trees are planted,the secondary flows rotate in the anticlockwise direction in the main channel and in the clockwise direction on the floodplain.In addition,for all cases,the intensities of the secondary currents on the floodplain are stronger than those in the main channel.

  9. Mixing Enhancement and Interface Characteristics in a Small-Scale Channel

    Science.gov (United States)

    Noro, Shuta; Kokunai, Kenji; Shigeta, Masaya; Izawa, Seiichiro; Fukunishi, Yu

    The interface characteristics in a millimeter-scale channel are investigated in order to find a technique to speed up fluid mixing. The channel is fabricated on an acrylic-resin plate, where a cavity is attached in the downstream region of a T-shaped conduit. The mixing effect is evaluated using a blue dye and a colorless liquid, which are alternately injected into the channel by two syringe pumps. The important factors for highly efficient mixing under the combination of alternate inflow and cavity are investigated. Two-dimensional and three-dimensional numerical simulations are also performed, and the results are compared those of the experiment. It is confirmed that the fractal dimension and interface length inside a cavity can be used as indicators to predict the mixing level in the downstream region, although they are not perfect. The importance of focusing on both the stretching rate of the interface and the concentration gradient where the stretching of the interface occurs is presented.

  10. Characteristic emission enhancement in the atmosphere with Rn trace using metal assisted LIBS

    International Nuclear Information System (INIS)

    Several characteristic emission lines from the metal targets (Cu, Zn and Pb) were investigated in trace presence of radon gas in the atmospheric air, using Q-SW Nd:YAG laser induced plasma inside a control chamber. The emission lines of metal species are noticeably enhanced in (Rn+air), relative to those in the synthetic air alone. Similar spectra were also taken in various sub-atmospheric environments in order to determine the optimum pressure for enhancement. Solid-state nuclear track detectors were also employed to count the tracks due to alpha particles for the activity assessment

  11. Complex measurements of aerosol and ion characteristics in the atmospheric boundary layer

    Science.gov (United States)

    Kikas, Iu. E.; Kolomiets, S. M.; Kornienko, V. I.; Mirme, A. A.; Sal'm, Ia. I.; Sergeev, I. Ia.; Tammet, Kh. F.

    Results of a comprehensive study of the characteristics of atmospheric ions and aerosols in the boundary layer during the summer season are reported. A study is also made of the kinetics of aerosol formation under conditions of high artificial ionization of the air by alpha and UV radiation. A high degree of correlation is shown to exist between atmospheric concentrations of medium ions and fine (less than 0.01 micron) aerosol. The results obtained support the radiation-chemical mechanism of aerosol formation.

  12. Flow and Heat Transfer Characteristics in Rotating Two-pass Channels Cooled by Superheated Steam

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; GAO Jianmin; XU Liang; SHI Xiaojun

    2012-01-01

    In a modern gas turbine,using superheated steam to cool the vane and blade for internal convection cooling is a promising alternative to traditional compressor air.However,further investigations of steam cooling need to be performed.In this paper,the three-dimensional flow and heat transfer characteristics of steam are numerically investigated in two-pass square channels with 45° ribbed walls under stationary and rotating conditions.The investigated rotation numbers are 0 and 0.24.The simulation is carried out by solving the Reynolds averaged Navier-Stokes equations employing the Reynolds stress turbulence model,cspccially considering two additional terms for Coriolis and rotational buoyancy forces caused by the rotating effect.For comparison,calculations for the air-cooled channels are done first at a Reynolds number of 25 000 and inlet coolant-to-wall density ratio of 0.13.The results are compared with the experiment data.Then the flow and heat transfer in steam-cooled channels are analyzed under the same operating conditions.The results indicate that the superheated steam has better heat transfer performance than air.Due to the combined effect of rotation,skewed ribs and 180° sharp turn,the secondary flow pattern in steam-cooled rotating two-pass channels is quite complex.This complex secondary flow pattern leads to strong anisotropic turbulence and high level of anisotropy of Reynolds stresses,which have a significant impact on the local heat transfer coefficient distributions.

  13. Characteristics of oscillating flow through a channel filled with open-cell metal foam

    International Nuclear Information System (INIS)

    An experimental study was performed to investigate the characteristics of oscillating flow through a channel filled with open-cell metal foam with a fully inter-connected pore structure. Detailed experimental data of oscillating flow pressure drops and velocities for a wide range of oscillatory frequency and the maximum flow displacement were presented. A correlation equation for the maximum friction factor of metal foams subject to oscillating flow was obtained and compared with the results for channels inserted with wire-screens obtained by other investigators. The results showed that oscillating flow characteristics in an open-cell metal foam are governed by a hydraulic ligament diameter based kinetic Reynolds number Re ω(Dh) and the dimensionless flow displacement amplitude A Dh. The effects of kinetic Reynolds number on the variations of pressure drop and flow velocity in metal foam are more significant than that of the dimensionless flow displacement amplitude. The maximum friction factor of oscillating flow in open-cell metal foams is much smaller than that of oscillating flow in wire-screens for large flow displacement amplitudes

  14. Experimental study on the stability characteristics of two-phase flows in parallel boiling channels under natural-circulation conditions

    International Nuclear Information System (INIS)

    Experimental study has been performed to study periodical-boiling instability in parallel channels, which occurs at low heat fluxes and is of concern in the start-up process of an SBWR. Three channels, made of glass tubes to facilitate visual observation, are placed in bulk water and are heated with electric heaters inserted in the channels. Two types of channels of different length are used to investigate the effect of unheated risers or chimney on periodical boiling. Relationship of bubble development and flow instability is also studied. It is found that slug bubbles are usually followed by rapid boiling, which results in high fluctuation of the flow. Refilling of the subcooled water from the top causes bubble condensation. Sometimes rapid condensation occurs and results in crack sounds. The longer channel does not necessarily have better coolability and stability characteristics; the average flow rate is actually lower and fluctuation amplitude is higher compared to those for the shorter channel

  15. Climatology of Gravity Wave Characteristics and Middle Atmosphere Thermal Structure Characteristics over Reunion Islands, France

    Science.gov (United States)

    Prasanth, Vishnu

    2016-07-01

    In this paper, climatological characteristics of the gravity wave activities and thermal structure activities are studied using temperature profiles obtained from Rayleigh lidar located at Reunion Island (20.8°S, 55.5°E) over a period of ~14 years (1994-2007). The study has been performed over the height range from 30 to 65 km. The overall monthly mean temperature shows a maximum of 265-270K at the stratopause height region from ˜44-52km and peaks during the months of March and November. While there is no clear signature of seasonal oscillation in the stratopause height, the stratopause temperature shows distinct maxima during the periods March-April and October-November. The GW characteristics in terms of time (frequency), height (wave number) and GW associated Potential Energy and their seasonal dependences are presented. Generally, the temporal evolution of temperature profile illustrates the downward phase propagation indicating that the energy is propagating upward. The wave activity is clearly visible with the wave periods ranging from 260 min to 32 min. The dominant components have vertical wavelengths in the range of about ~4 km to 35 km. It is found that the seasonal variation of potential energy is maximum during summer in the upper stratosphere and lower mesosphere. A semiannual variation is seen in the gravity wave activity over all height ranges in the months of February and August.

  16. Trap density of states in n-channel organic transistors: variable temperature characteristics and band transport

    International Nuclear Information System (INIS)

    We have investigated trap density of states (trap DOS) in n-channel organic field-effect transistors based on N,N ’-bis(cyclohexyl)naphthalene diimide (Cy-NDI) and dimethyldicyanoquinonediimine (DMDCNQI). A new method is proposed to extract trap DOS from the Arrhenius plot of the temperature-dependent transconductance. Double exponential trap DOS are observed, in which Cy-NDI has considerable deep states, by contrast, DMDCNQI has substantial tail states. In addition, numerical simulation of the transistor characteristics has been conducted by assuming an exponential trap distribution and the interface approximation. Temperature dependence of transfer characteristics are well reproduced only using several parameters, and the trap DOS obtained from the simulated characteristics are in good agreement with the assumed trap DOS, indicating that our analysis is self-consistent. Although the experimentally obtained Meyer-Neldel temperature is related to the trap distribution width, the simulation satisfies the Meyer-Neldel rule only very phenomenologically. The simulation also reveals that the subthreshold swing is not always a good indicator of the total trap amount, because it also largely depends on the trap distribution width. Finally, band transport is explored from the simulation having a small number of traps. A crossing point of the transfer curves and negative activation energy above a certain gate voltage are observed in the simulated characteristics, where the critical VG above which band transport is realized is determined by the sum of the trapped and free charge states below the conduction band edge

  17. Characteristics of atmospheric gravity waves observed using the MU (Middle and Upper atmosphere) radar and GPS (Global Positioning System) radio occultation.

    Science.gov (United States)

    Tsuda, Toshitaka

    2014-01-01

    The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10-100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In this paper, we summarize the characteristics of atmospheric gravity waves observed using the middle and upper atmosphere (MU) radar in Japan, as well as novel satellite data obtained from global positioning system radio occultation (GPS RO) measurements. In particular, we focus on the behavior of gravity waves in the mesosphere (50-90 km), where considerable gravity wave attenuation occurs. We also report on the global distribution of gravity wave activity in the stratosphere (10-50 km), highlighting various excitation mechanisms such as orographic effects, convection in the tropics, meteorological disturbances, the subtropical jet and the polar night jet. PMID:24492645

  18. Experimental study of friction and heat transfer characteristics in narrow rectangular channel

    International Nuclear Information System (INIS)

    Highlights: ► The Nusselt number increases with the fluid temperature difference in turbulent flow. ► Heat transfer temperature difference increases with Re in laminar flow. ► Heat transfer temperature difference does not change significantly in turbulent flow. ► A correlation for heat transfer calculation in turbulent flow is introduced. - Abstract: This work presents an experimental investigation of the friction and heat transfer characteristics in a narrow rectangular channel. Nine groups of experiments are conducted and the fluid temperature difference between the inlet and outlet of the test section is kept constant in each experimental run. The results show that the friction factors in isothermal condition can be well correlated by the Leon correlation for the developed laminar and turbulent flow, and the Bhatti and Shah correlation for the laminar to turbulent transition region. In addition, the friction factors prediction correlations in non-isothermal condition are proposed based on the viscosity ratio method. The heat transfer characteristic is not affected by the change of temperature difference in laminar flow. However, as in the fully developed turbulent flow, the Prandtl number significantly influences the heat transfer characteristic. The heat transfer temperature difference between the wall and fluid increases with the increase of Reynolds number in the laminar flow, and decreases sharply as the flow enters the transition region. However, it does not present a significant variation in the fully developed turbulent flow regime. Based on the analysis of heat transfer temperature difference, a new correlation for calculating the Nusselt number in the turbulent flow regime of a rectangular channel is introduced and the agreement between experimental data and predicted values is satisfactory.

  19. Altitude dependence of intensity and γ-family characteristics at various atmospheric depths

    International Nuclear Information System (INIS)

    The model with scaling violation in pionization region is used to Monte-Carlo-calculation the characteristics of γ-families at various atmospheric levels for complex chemical composition of the primary cosmic ray spectrum. The results bearing on the altitude dependence of intensity and on the lateral and longitudinal characteristics of the families are presented. The effect of inelastic charge exchange of the leading meson is discussed. The calculated and experimental results are intercompared. The possibility of absence of charge exchange is discussed. (author)

  20. Performance analysis of relay-assisted all-optical FSO networks over strong atmospheric turbulence channels with pointing errors

    KAUST Repository

    Yang, Liang

    2014-12-01

    In this study, we consider a relay-assisted free-space optical communication scheme over strong atmospheric turbulence channels with misalignment-induced pointing errors. The links from the source to the destination are assumed to be all-optical links. Assuming a variable gain relay with amplify-and-forward protocol, the electrical signal at the source is forwarded to the destination with the help of this relay through all-optical links. More specifically, we first present a cumulative density function (CDF) analysis for the end-to-end signal-to-noise ratio. Based on this CDF, the outage probability, bit-error rate, and average capacity of our proposed system are derived. Results show that the system diversity order is related to the minimum value of the channel parameters.

  1. Characteristic times in the English Channel from numerical modelling: supporting decision-making

    Energy Technology Data Exchange (ETDEWEB)

    Perianez, R [Departamento de Fisica Aplicada 1, Universidad de Sevilla, EUITA, Carretera Utrera km 1, 41013 Sevilla (Spain); Miro, C [Departamento de Fisica Aplicada, Facultad de Veterinaria, Universidad de Extremadura, Avenida de la Universidad s/n, 10071 Caceres (Spain)], E-mail: rperianez@us.es, E-mail: cmiro@unex.es

    2009-06-15

    A numerical model that simulates the dispersion of radionuclides in the English Channel has been applied to study the dispersion of conservative and non-conservative radionuclides released from the La Hague nuclear fuel reprocessing plant. The model is based upon previous work and now is able to simulate dispersion over long timescales (decades), explicitly including transport by instantaneous tidal currents and variable wind conditions. Wind conditions are obtained from meteorological statistics using a stochastic method. Outputs from the model are treated using time-series analysis techniques. These techniques allow the determination of characteristic times of the system, transport velocities and dispersion factors. This information may be very useful to support the decision-making process after an emergency situation. Thus, we are proposing that time-series analysis can be integrated with numerical modelling for helping decision-making in response to an accident. The model is first validated through its application to actual releases of {sup 99}Tc and {sup 125}Sb, comparing measured and computed concentrations, and characteristic times for three radionuclides are given next: a perfectly conservative one, a very reactive one ({sup 239,240}Pu) and {sup 137}Cs, which has an intermediate behaviour. Characteristic transport velocities and dispersion factors have been calculated as well. Model results are supported by experimental evidence.

  2. Effects of rolling motion on thermal–hydraulic characteristics of boiling flow in rectangular narrow channel

    International Nuclear Information System (INIS)

    Highlights: • Pressure drop fluctuation is enhanced with increasing rolling amplitude and period. • The phase difference between flow rate and pressure drop fluctuation is 1/4 period. • Amplitude of boiling heat transfer coefficient increases with increasing heat flux. • The curve of boiling heat transfer coefficient fluctuations is close to sine curve. - Abstract: Experimental investigations on thermal–hydraulic characteristics of boiling flow in a rectangular narrow channel under rolling motion conditions are carried out. This experiment is designed to elucidate the phenomena of boiling flow under rolling motion and to give the corresponding rational explanations. The results show that the amplitudes of fluctuations of pressure drop, flow rate, fluid and wall temperatures, and boiling heat transfer coefficient increase with the increasing of rolling amplitude and rolling period. The phase difference of flow rate fluctuation and pressure drop fluctuation is 1/4 period, and the saturated water temperature fluctuations of the test section delay 2–3 s behind the pressure drop fluctuations. The time average boiling heat transfer coefficients of the rectangular narrow channel under rolling motion are equal to those under static conditions. The amplitude of boiling heat transfer coefficient of test section increases with increasing heat flux and flow rate, while decreases with increasing system pressure

  3. Heat transfer characteristics of one-side heated vertical rectangular channel inserting porous material

    International Nuclear Information System (INIS)

    In the Very High Temperature Reactor (VHTR) which is the next generation nuclear reactor system, ceramics and graphite are used as the fuel coating material and the core structural material, respectively. From the view point of the safety characteristic, the passive cooling system should be designed for the VHTR as the best way of the reactor and vessel cooling systems (VCS). So, the gas cooling system by natural convection is the one of candidate system for the VCS of the VHTR. This study is to develop the passive cooling system for the VHTR using the vertical rectangular channel inserting porous materials. From the results obtained in this experiment, it was found that the amount of transferred heat from the heated wall will be increased even if the heat removed by natural convection. (author)

  4. Investigation of capacitance voltage characteristics of strained Si/SiGe n-channel MODFET varactor

    Science.gov (United States)

    Elogail, Y.; Kasper, E.; Gunzer, F.; Shaker, A.; Schulze, J.

    2016-06-01

    This work is concerned with the investigation of Capacitance-Voltage (CV) behavior of n-channel Si/SiGe MODFET varactors. This investigation provides a valuable insight into the high frequency response of the device under test and its dependence on design parameters; especially regarding the modulation layer doping concentration. The heterostructure under consideration is much more complicated than conventional MOS varactor with respect to non-uniform doping, energy band offsets and the pn-junction in series. Subsequently, CV characterization has never been applied to such MODFET varactor structure. Experimental CV measurements have shown a non-monotonic behavior with a transition point minimum and higher saturation levels on both sides, in contradiction to the conventional high frequency MOS characteristics. This behavior was confirmed qualitatively using simulations. Moreover, we explain some fundamental capacitance properties of the structure, which provide already very interesting perceptions of the MODFET varactor operation, modeling and possible applications using the obtained stimulating results.

  5. Characteristics of frictional pressure drop in narrow rectangular channel in rolling motion

    International Nuclear Information System (INIS)

    Single-phase flow and flow boiling resistances of water in narrow rectangular channel in rolling motion were investigated experimentally, the transient pressure drop characteristics were obtained and the mechanism of rolling motion effect on pressure drop oscillation was also analyzed. Rolling motion leads to the periodical fluctuation of frictional pressure drop. In the case of single-phase flow, the effect of rolling motion weakens with the increase of flow rate and temperature. While for flow boiling, position change of the system due to the rolling motion results in the fluctuation of pressure drop, of which the amplitude increases with the flow rate, vapor quality as well as rolling angle and period, and decreases with the increase of system pressure. (authors)

  6. Numerical Study of Non-Newtonian Flow Characteristics in Sudden Contraction-Expansion Channel

    International Nuclear Information System (INIS)

    Because most existing non-Newtonian models are not suitable for application to the lattice Boltzmann method, theoretical and numerical studies in this regard remain challenging. In this study, the hydro kinetic (HK) model was modified and applied to a 3a sudden contraction-expansion channel flow, and the characteristics of the H K model flow were evaluated to generate non-trivial predictions in three-dimensional strong shear flows. The HK model is very efficient for application to the lattice Boltzmann method because it utilizes the shear rate and relaxation time. However, the simulation would be unstable in a high shear flow field because the local relaxation time sharply decreases with an increase in the shear rate in a strong shear flow field. In the HK model, it may become necessary to truncate the relaxation time and non-dimensional parameter to obtain stable numerical results

  7. Stability characteristics of the open channel flow above the asymmetrical irregular sand ripples

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Sandy bed cannot keep its original smoothness as the flows pass. With the increase of the flow intensity, the bed forms will appear as sand ripples and dune in turn. Among these morphologies, the sand ripple scale is the smallest, which is generally symmetrical when it just appears, but as time goes on, the asymmetrical form gradually develops. Just because of this sand ripples asymmetry, it manifests the influence of the flow on the bed morphology and also the impact on the laminar flow dynamical process, especially the stability characteristics. The stability features of laminar flow on open channels with the asymmetrical sand ripples are discussed, and also the results on the symmetrical sand ripples are compared in detail.

  8. Numerical Study of Non-Newtonian Flow Characteristics in Sudden Contraction-Expansion Channel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung Min [Kyonggi Univ., Suwon (Korea, Republic of)

    2013-06-15

    Because most existing non-Newtonian models are not suitable for application to the lattice Boltzmann method, theoretical and numerical studies in this regard remain challenging. In this study, the hydro kinetic (HK) model was modified and applied to a 3a sudden contraction-expansion channel flow, and the characteristics of the H K model flow were evaluated to generate non-trivial predictions in three-dimensional strong shear flows. The HK model is very efficient for application to the lattice Boltzmann method because it utilizes the shear rate and relaxation time. However, the simulation would be unstable in a high shear flow field because the local relaxation time sharply decreases with an increase in the shear rate in a strong shear flow field. In the HK model, it may become necessary to truncate the relaxation time and non-dimensional parameter to obtain stable numerical results.

  9. Pollution characteristics of atmospheric fine particles and their secondary components in the atmosphere of Shenzhen in summer and in winter

    Institute of Scientific and Technical Information of China (English)

    NIU Yuwen; HE Lingyan; HU Min; ZHANG Jing; ZHAO Yunliang

    2006-01-01

    Two field measurements for atmospheric fine particles were conducted in Baoan district of Shenzhen during the summer and winter in 2004. Totally 30 sets of 24 h samples were collected, and then the mass concentrations and chemical compositions were determined. The seasonal variations and secondary pollution characteristics of fine particles during the sampling periods were discussed with meteorological factors. The results show that seasonal variations of atmospheric particles are significant in Shenzhen. The average mass concentrations of PM2.5 and PM10 in summer were 35 μg·m-3 and 57 μg·m-3, respectively, and those in winter were 99 μg·m-3 and 135 μg·m-3, respectively. The concentrations of both PM2.5 and PM10 in winter increased 184% and 137%, respectively, compared to those in summer. PM2.5 accounted for 61% and 75% of PM10 in summer and in winter, respectively, indicating severe fine particle pollution in Shenzhen. During the summer and winter sampling periods, the mean OC/EC ratios were 3.4 and 1.6, respectively. The estimated secondary organic carbon (SOC) averagely accounted for 56% and 6% of the total OC in summer and in winter, respectively, which implies a major contribution of SOC to OC in summer. During the continuous high temperature period in summer, both the concentrations and fractions of secondary aerosol components in PM2.5 were highly elevated, suggesting severe secondary pollution again. The prevailing wind was from South China Sea in summer, and the air quality was good. The prevailing wind in winter was from Mainland China to the north, and the polluted air mass led to poor air quality.

  10. Influence of characteristics of irrigation channels on the breeding bird community of a wetland zone in southeast of Spain

    OpenAIRE

    López Pomares, Alejandro; López Iborra, Germán Manuel; Martín Cantarino, Carlos

    2009-01-01

    The “El Hondo Nature Park” is mainly composed of a series of irrigation channels and water reservoirs, subjected to various regimes of management as well as reed and vegetation control, thus creating a great variety of habitats and situations. To determine the influence of these habitats and management regimes on the local bird community, a set of characteristics of these channels and their surrounding area were analysed with a Correspondence Analysis (CA). The degree of reed development in c...

  11. Sensitivity of the sea circulation to the atmospheric forcing in the Sicily Channel

    Science.gov (United States)

    Omrani, Hiba; Arsouze, Thomas; Béranger, Karine; Boukthir, Moncef; Drobinski, Philippe; Lebeaupin-Brossier, Cindy; Mairech, Hanen

    2016-01-01

    We investigate the sensitivity of the sea surface circulation in the Sicily Channel to surface winds, using a 15-year long (1994-2008) air-sea coupled numerical simulation. Analysis is based on the clustering of six main wind regimes over the Sicily Channel domain. The analysis of the corresponding sea current clusters shows that sea circulation in this area is sensitive to surface wind patterns. This wind modulates the strength of the two main branches of the sea circulation in the Sicily Channel (i.e. the Atlantic Tunisian Current and the Atlantic Ionian Stream). The modulation of these two currents depends on the wind regime, and displays a strong seasonal variability. It is also shown that the sea circulation in the Sicily Channel is strongly controlled by the thermohaline circulation and the bathymetry (geostrophic current). However, the contribution to the total current of its ageostrophic component forced by the surface winds is significant, with a correlation coefficient varying from 0.3 to 0.7.

  12. Optical and electrical characteristics of air dielectric barrier discharges in mode transition at atmospheric pressure

    International Nuclear Information System (INIS)

    Atmospheric pressure dielectric barrier discharges (DBDs) have a wide range of industrial applications, generally exhibiting either filamentary or diffuse (i.e. glow) discharges. The focus of this investigation is on the formation mechanisms of the discharge current pulse width, on the order of tens of microseconds, accompanied by a light source formation, which is called a light source (LS) mode in air DBDs at atmospheric pressure. From a macroscopic point of view, the characteristics of the discharge current in the LS mode are similar with those of the glow mode. The optical and electrical characteristics of air DBDs at atmospheric pressure are investigated in the transition from the filamentary mode to the LS mode by measuring the optical emission spectroscopy and electrical signals. It is shown that in the manual increasing voltage stage, the vibrational temperature almost never changes and the gas temperature, electron temperature, dielectric capacitance, gas voltage (Vg) and discharge power (P) increase with an increase in the applied voltage. In the automatic decreasing voltage stage, all of these parameters, except Vg and P, increase with a decrease in the voltage. But, when the voltage decreases to a minimum value corresponding to the LS mode, P reaches a maximum value. In this paper, the variations of these parameters are analyzed and discussed in detail. The formation of the LS mode originates from the secondary electrons. The formation mechanisms of the secondary electrons are also discussed. (paper)

  13. Numerical analysis of characteristics of atmospheric dispersion around Tokai nuclear site for emergency plan

    International Nuclear Information System (INIS)

    In order to make an effective countermeasure plan against an accidental release of radioactivity, it is important to grasp characteristics of atmospheric dispersion in objective areas beforehand. This paper describes the numerical analysis of characteristics of atmospheric dispersion and dose distribution in an emergency around the Tokai nuclear site, based on the analysis of observed meteorological data. Analysis of meteorological data at Tokai shows that steady flows from the northeast and land-sea breeze circulations characterize contamination of the land. Results obtained from simulations of atmospheric dispersion under such conditions are: 1) The dose distribution can be represented approximately by Gaussian plume model, when radioactivity is discharged into the steady northeast wind. 2) In the case of a short term release for the period of wind changing from the land to sea breeze, the dose distribution is formed in the shape of an unfolded fun with an angle of approximately 90deg. The high contamination area is sometimes 1.5 times larger than that of the steady wind case. (author)

  14. Numerical modeling of DPSK pressure signals and their transmission characteristics in mud channels

    Institute of Scientific and Technical Information of China (English)

    Shen Yue; Su Yinao; Li Gensheng; Li Lin; Tian Shouceng

    2009-01-01

    A numerical model and transmission characteristic analysis of DPSK (differential phase shift keying) pressure signals in mud channels is introduced. With the control logic analysis of the rotary valve mud telemetry, a logical control signal is built from a Gate function sequence according to the binary symbols of transmitted data and a phase-shift function is obtained by integrating the logical control signal. A mathematical model of the DPSK pressure signal is built based on principles of communications by modulating carrier phase with the phase-shift function and a numerical simulation of the pressure wave is implemented with the mathematical model by MATLAB programming. Considering drillpipe pressure and drilling fluid temperature profile along drillpipes, the drillpipe of a vertical well is divided into a number of sections. With water-based drilling fluids, the impacts of travel distance, carrier frequency, drillpipe size, and drilling fluids on the signal transmission were studied by signal transmission characteristic analysis for all the sections. Numerical calculation results indicate that the influences of the viscosity of drilling fluids and volume fraction of gas in drilling fluids on the DPSK signal transmission are more notable than the others and the signal will distort in waveform with differential attenuations of the signal frequent component.

  15. TARGET 5: a new multi-channel digitizer with triggering capabilities for gamma-ray atmospheric Cherenkov telescopes

    CERN Document Server

    Albert, A; Kawashima, T; Murphy, M; Okumura, A; Quagliani, R; Sapozhnikov, L; Tajima, H; Tibaldo, L; Vandenbroucke, J; Wu, T

    2016-01-01

    TARGET~5 is a new application-specific integrated circuit (ASIC) of the TARGET family, designed for the readout of signals from photosensors in the cameras of imaging atmospheric Cherenkov telescopes (IACTs) for ground-based gamma-ray astronomy. TARGET~5 combines sampling and digitization on 16 signal channels with the formation of trigger signals based on the analog sum of groups of four channels. {\\rev We describe the ASIC architecture and performance.} TARGET~5 improves over the performance of the first-generation TARGET ASIC, achieving: tunable sampling frequency from {\\rev $1$~GSa/s}}; a dynamic range on the data path of 1.2 V with {\\mod effective dynamic range of 11}~bits and DC noise of ${\\sim}0.6$~mV; 3-dB bandwidth of 500 MHz; {\\rev crosstalk between adjacent channels $100$~p.e.} (assuming 4 mV per p.e.); and minimum stable trigger threshold of 20 mV (5 p.e.) with trigger noise of 5 mV (1.2 p.e.), {\\rev which is} mostly limited by {\\mod interference between trigger and sampling operations}. {\\mod TAR...

  16. Maximizing Channel Capacity based on Antenna and MIMO Channel Characteristics and its Application to Multimedia Data Transmission

    Science.gov (United States)

    Pottkotter, Andrew

    Communication transmission between electronic devices is evolving at an ever faster pace. There are now more electronic handheld devices that we communicate with on a daily basis. The allotted bandwidth and speed for these devices are limited by hardware, software, handshaking capabilities between each electronic application. The demand for information at high data rates without the loss of reliability has evolved antenna technology and digital signal processing into more complex systems utilizing multiple processors and multiple antennas. This paper discusses the various techniques used to increase data speed, enhance channel capacity, and reliability of application specific devices with respect to the Multiple-Input-to-Multiple-Output (MIMO) based methods. MIMO based applications can improve the data speed, channel capacity, and reliability of the system with maximum limitations based on hardware, coding schemes, and handshaking abilities between devices.

  17. Hydrometeorological characteristics of rain-on-snow events associated with atmospheric rivers

    Science.gov (United States)

    Guan, Bin; Waliser, Duane E.; Ralph, F. Martin; Fetzer, Eric J.; Neiman, Paul J.

    2016-03-01

    Atmospheric rivers (ARs) are narrow, elongated, synoptic corridors of enhanced water vapor transport that play an important role in regional weather/hydrology. Rain-on-snow (ROS) events during ARs present enhanced flood risks due to the combined effects of rainfall and snowmelt. Focusing on California's Sierra Nevada, the study identifies ROS occurrences and their connection with ARs during the 1998-2014 winters. AR conditions, which occur during 17% of all precipitation events, are associated with 50% of ROS events (25 of 50). Composite analysis shows that compared to ARs without ROS, ARs with ROS are on average warmer by ~2 K, with snow water equivalent loss of ~0.7 cm/d (providing 20% of the combined water available for runoff) and ~50% larger streamflow/precipitation ratios. Atmospheric Infrared Sounder retrievals reveal distinct offshore characteristics of the two types of ARs. The results highlight the potential value of observing these events for snow, rain, and flood prediction.

  18. Discharge Characteristics in Atmospheric Pressure Glow Surface Discharge in Helium Gas

    Institute of Scientific and Technical Information of China (English)

    LI Xue-Chen; WANG Long

    2005-01-01

    @@ Atmospheric pressure glow discharge is observed for the first time in a surface discharge generator in flowing helium. Electrical and optical methods are used to measure the characteristics of atmospheric pressure glow discharge for different voltages. The results show that discharge current waveforms are asymmetric for the different polarities of the applied voltage. A continuous discharge profile with a width of several microseconds appears for per half cycle of the applied voltage when the voltage is increased to a certain value. The short-pulsed discharge and the continuous current would result from the Townsend breakdown and glow discharge mechanisms respectively. The properties of surface discharge in stagnant helium are completely different from that in flowing helium.

  19. Do the characteristics of the ichthyoplankton in an artificial and a natural entrance channel of a large estuary differ?

    Science.gov (United States)

    Young, G. C.; Potter, I. C.

    2003-03-01

    The Peel-Harvey Estuary in south-western Australia became so eutrophic in the 1970s and 1980s that a radical approach was adopted in order to increase tidal exchange between this estuary and the ocean and thereby flush greater volumes of nutrients out to sea. This involved constructing a deep artificial (Dawesville) channel between the estuary and the ocean, at a location ca. 15 km south of the shallower and natural (Mandurah) channel. Samples of fish larvae were collected monthly throughout 1997 to determine whether the characteristics of the ichthyoplankton on flood and ebb tides differed within and between channels and whether they underwent the same types of intra-annual changes in the two channels. In both channels, the number of species and concentration of larvae were both significantly greater on flood than ebb tides and the species composition differed significantly between tides. The concentrations of larvae were at their greatest, by far, between early spring and early autumn. Flood and ebb tides in both channels were dominated by the goby Favonigobius lateralis, which was transported out on ebb tides as preflexion larvae and subsequently brought back on flood tides as postflexion larvae. The larvae of Hyperlophus vittatus, Pseudorhombus jenynsii and Rhabdosargus sarba, which spawn outside the estuary, were far more abundant on flood than ebb tides, whereas the reverse pertained with Atherinosoma elongata, Apogon rueppellii and Pseudogobius olorum, which spawn within the estuary. In contrast to the situation with the diversity and concentration of larvae, the species composition on both flood and ebb tides differed significantly between channels. However, the latter differences were small and mainly due to relatively greater numbers of larval F. lateralis on ebb tides in the Mandurah Channel and the very occasional occurrence of reef species on flood tides in the Dawesville Channel. During the year, the species composition underwent cyclical changes on

  20. Analysis of channel evolution characteristics in the Hobq Desert reach of the Yellow River (1962-2000)

    Science.gov (United States)

    Pan, Baotian; Guan, Qingyu; Liu, Zibian; Gao, Hongshan

    2015-12-01

    A series of problems, resulting from sediment deposition and channel silting, have occurred on the Hetao Plain as a result of changes to the Hobq Desert reach of the Yellow River. Therefore, improved research on channel evolution in this reach is vitally important. Using profile data from 80 channel cross-sections obtained in 1962, 1982, 1991 and 2000 from the Yellow River in the Hobq Desert, we showed that there was serious sediment deposition here (especially for the tributary section in the eastern desert) and that maximum sediment deposition occurred during 1982-1991. As sediment was deposited along the mobile channel, the channel trunk shrank and moved to the north. The characteristics of river channel evolution are dramatically different between the western and the eastern Hobq Desert reaches of the Yellow River, which include desert and the tributary sections, respectively. Erosion mainly occurred in the desert section, whereas sediment deposition occurred in the tributary section, with peak values at the mouths of on Yellow River tributaries. The desert section had a larger average erosion rate and smaller accumulation rate than the tributary section. The influences of tectonic movement and stream gradient on channel evolution in this fluvial reach were minimal. The sediment inputs from ten Yellow River tributaries (especially during flood seasons) have dominated channel evolution in these tributaries. The building of artificial levées has intensified sediment deposition in the channel, whereas the reduction of mainstream discharge (especially in the flood seasons), caused by the operation of reservoirs and water diversion activities (such as for agricultural irrigation), has further intensified the sediment deposition in the river channel.

  1. Estimating design-flood discharges for streams in Iowa using drainage-basin and channel-geometry characteristics

    Science.gov (United States)

    Eash, D.A.

    1993-01-01

    Drainage-basin and channel-geometry multiple-regression equations are presented for estimating design-flood discharges having recurrence intervals of 2, 5, 10, 25, 50, and 100 years at stream sites on rural, unregulated streams in Iowa. Design-flood discharge estimates determined by Pearson Type-Ill analyses using data collected through the 1990 water year are reported for the 188 streamflow-gaging stations used in either the drainage-basin or channel-geometry regression analyses. Ordinary least-squares multiple-regression techniques were used to identify selected drainage-basin and channel-geometry characteristics and to delineate two channel-geometry regions. Weighted least-squares multiple-regression techniques, which account for differences in the variance of flows at different gaging stations and for variable lengths in station records, were used to estimate the regression parameters.

  2. The Analyses of Turbulence Characteristics in the Atmospheric Surface Layer Using Arbitrary-Order Hilbert Spectra

    Science.gov (United States)

    Wei, W.; Schmitt, F. G.; Huang, Y. X.; Zhang, H. S.

    2016-05-01

    Turbulent characteristics in the atmospheric surface layer are investigated using a data-driven method, Hilbert spectral analysis. The results from empirical mode decomposition display a set of intrinsic mode functions whose characteristic scales suggest a dyadic filter-bank property. It can be concluded from the joint probability density function of the intrinsic mode functions that the turbulent properties are totally different under different stratifications: the amplitudes (or energies) are arranged according to the stability parameter [InlineEquation not available: see fulltext.] for stable conditions, but tend to cluster randomly for unstable cases. The intermittency analyses reveal that second-order Hilbert marginal spectra display a power-law behaviour in the inertial subrange, and that the scaling exponent functions deviate from the theoretical values due to the strong intermittency in the stable boundary layer.

  3. Experimental study on single-phase convection heat transfer characteristics of pebble bed channels with internal heat generation

    International Nuclear Information System (INIS)

    The water-cooled pebble bed reactor core is the porous channels stacked with spherical fuel elements, having evident effect on enhancing heat transfer. Owing to the variability and randomness characteristics of it's interstice, pebble bed channels have a very complex heat transfer situation and have little correlative research. In order to research the heat transfer characters of pebble bed channels with internal heat source, electromagnetic induction heating method was adopted for overall heating the pebble bed which was composed of 8 mm diameter steel balls, and the internal heat transfer characteristics were researched. By comparing and analyzing the experimental data, the rule of power distribution and heat transfer coefficient with heat flux density, inlet temperature and working fluid's Re were got. According to the experimental data fitting, the dimensionless average heat transfer coefficient correlation criteria was got. The fitting results are good agreement with the experimental results within 12% difference. (authors)

  4. Enhancement heat transfer characteristics in the channel with Trapezoidal rib–groove using nanofluids

    Directory of Open Access Journals (Sweden)

    Ali Najah Al-Shamani

    2015-03-01

    Full Text Available Numerical study of heat transfer due to turbulent flow of nanofluids through rib–groove channel have been investigated. The continuity, momentum and energy equations are solved by the finite volume method (FVM. Four different rib–groove shapes have been examined. Four different types of nanoparticles, Al2O3, CuO, SiO2, and ZnO with different volumes fractions in the range of 1–4% and different nanoparticle diameter in the range of 25–70 nm, have been also studied. The computations are performed under constant temperature over a range of Reynolds number (Re 10,000–40,000. Results indicate that the Trapezoidal with increasing height in the flow direction rib–trapezoidal groove has the best heat transfer rate and high Nusselt number. It is also found that the SiO2 – nanofluid has the highest value of Nusselt number in comparison with the other type of nanofluids. The Nusselt number increases as the volume fraction increases and it decreases as the nanoparticle diameter increases. The present study shows that these Trapezoidal rib–groove using nanofluids have the potential to dramatically increase heat transfer characteristics and thus can be good candidates for the development of efficient heat exchanger device.

  5. A multihop key agreement scheme for wireless ad hoc networks based on channel characteristics.

    Science.gov (United States)

    Hao, Zhuo; Zhong, Sheng; Yu, Nenghai

    2013-01-01

    A number of key agreement schemes based on wireless channel characteristics have been proposed recently. However, previous key agreement schemes require that two nodes which need to agree on a key are within the communication range of each other. Hence, they are not suitable for multihop wireless networks, in which nodes do not always have direct connections with each other. In this paper, we first propose a basic multihop key agreement scheme for wireless ad hoc networks. The proposed basic scheme is resistant to external eavesdroppers. Nevertheless, this basic scheme is not secure when there exist internal eavesdroppers or Man-in-the-Middle (MITM) adversaries. In order to cope with these adversaries, we propose an improved multihop key agreement scheme. We show that the improved scheme is secure against internal eavesdroppers and MITM adversaries in a single path. Both performance analysis and simulation results demonstrate that the improved scheme is efficient. Consequently, the improved key agreement scheme is suitable for multihop wireless ad hoc networks. PMID:23766725

  6. MIMO free-space optical communication employing coherent BPOLSK modulation in atmospheric optical turbulence channel with pointing errors

    Science.gov (United States)

    Prabu, K.; Kumar, D. Sriram

    2015-05-01

    An optical wireless communication system is an alternative to radio frequency communication, but atmospheric turbulence induced fading and misalignment fading are the main impairments affecting an optical signal when propagating through the turbulence channel. The resultant of misalignment fading is the pointing errors, it degrades the bit error rate (BER) performance of the free space optics (FSO) system. In this paper, we study the BER performance of the multiple-input multiple-output (MIMO) FSO system employing coherent binary polarization shift keying (BPOLSK) in gamma-gamma (G-G) channel with pointing errors. The BER performance of the BPOLSK based MIMO FSO system is compared with the single-input single-output (SISO) system. Also, the average BER performance of the systems is analyzed and compared with and without pointing errors. A novel closed form expressions of BER are derived for MIMO FSO system with maximal ratio combining (MRC) and equal gain combining (EGC) diversity techniques. The analytical results show that the pointing errors can severely degrade the performance of the system.

  7. Flow characteristics on the blade channel vortex in the Francis turbine

    Science.gov (United States)

    Guo, P. C.; Wang, Z. N.; Luo, X. Q.; Wang, Y. L.; Zuo, J. L.

    2016-05-01

    Depending on the long-term hydraulic development of Francis turbine, the blade channel vortex phenomenon was investigated systematically from hydraulic design, experimental and numerical computation in this paper. The blade channel vortex difference between the high water head and low water head turbine was also analyzed. Meanwhile, the relationship between the blade channel vortex and the operating stability of hydraulic turbine was also investigated. The results show that the phenomenon of blade channel vortex is an intrinsic property for Francis turbine under small flow rate condition, the turning-point of the blade channel vortex inception curve appears at low unit speed region, and the variation trend of the blade channel vortex inception curve is closely related to the blade inlet edge profile. In addition to, the vortex of the high water head turbine can generally be excluded from the stable operation region, while which is more different for the one of the low water head turbine.

  8. Characteristic Analysis on UAV-MIMO Channel Based on Normalized Correlation Matrix

    OpenAIRE

    Gao Xi jun; Chen Zi li; Hu Yong Jiang

    2014-01-01

    Based on the three-dimensional GBSBCM (geometrically based double bounce cylinder model) channel model of MIMO for unmanned aerial vehicle (UAV), the simple form of UAV space-time-frequency channel correlation function which includes the LOS, SPE, and DIF components is presented. By the methods of channel matrix decomposition and coefficient normalization, the analytic formula of UAV-MIMO normalized correlation matrix is deduced. This formula can be used directly to analyze the condition numb...

  9. Pressure Effects on Product Channels of Hydrocarbon Radical-Radical Reactions; Implications for Modelling of Planetary Atmospheres

    Science.gov (United States)

    Fahr, A.; Halpern, J.; N'doumi, M.

    2011-10-01

    Previously we had studied the kinetics and product channels of small unsaturated hydrocarbon radical (C2 and C3s) reactions relevant to planetary atmospheric modelling. Reactions of C2 radicals (such as vinyl, H2CCH and ethynyl C2H) and C3 radicals (such as propargyl, HCCCH2 and allyl, H2CCCH3) can affect the abundances of a large number of stable observable C3, C4, C5, C6 and larger molecules, including linear, aromatic and even poly aromatic molecules. We have experimentally determined pressuredependent product yields for self- and cross-radical reactions performed at 298 K and at selected pressures between ~4 Torr (0.5 kPa) and 760 Torr (101 kPa). Final products were determined by gas chromatograph with mass spectrometry/flame ionization detection (GC/MS/FID). In some cases complementary computational studies extended the pressure and temperature range of the observations and provided valuable information on complex reaction mechanisms. These studies provide a systematic framework so that important energetic and structural parameters for radical-radical reactions can be assessed. Here we report a compilation of our earlier results relevant to planetary atmospheres in addition to recent ones for allyl radical (H2CCCH3) reactions.

  10. Spoilage and safety characteristics of ground beef packaged in traditional and modified atmosphere packages.

    Science.gov (United States)

    Brooks, J C; Alvarado, M; Stephens, T P; Kellermeier, J D; Tittor, A W; Miller, M F; Brashears, M M

    2008-02-01

    Two separate studies, one with pathogen-inoculated product and one with noninoculated product, were conducted to determine the safety and spoilage characteristics of modified atmosphere packaging (MAP) and traditional packaging of ground beef patties. Ground beef patties were allotted to five packaging treatments (i) control (foam tray with film overwrap; traditional), (ii) high-oxygen MAP (80% 02, 20% CO2), (iii) high-oxygen MAP with added rosemary extract, (iv) low-oxygen carbon monoxide MAP (0.4% CO, 30% CO2, 69.6% N2), and (v) low-oxygen carbon monoxide MAP with added rosemary extract. Beef patties were evaluated for changes over time (0, 1, 3, 5, 7, 14, and 21 days) during lighted display. Results indicated low-oxygen carbon monoxide gas flush had a stabilizing effect on meat color after the formation of carboxymyoglobin and was effective for preventing the development of surface discoloration. Consumers indicated that beef patties packaged in atmospheres containing carbon monoxide were more likely to smell fresh at 7, 14, and 21 days of display, but the majority would probably not consume these products after 14 days of display because of their odor. MAP suppressed the growth of psychrophilic aerobic bacteria when compared with control packages. Generally, control packages had significantly higher total aerobic bacteria and Lactobacillus counts than did modified atmosphere packages. In the inoculated ground beef (approximately 10(5) CFU/g) in MAP, Escherichia coli O157 populations ranged from 4.51 to 4.73 log CFU/g with no differences among the various packages, but the total E. coli O157:H7 in the ground beef in the control packages was significantly higher at 5.61 log CFU/g after 21 days of storage. On days 14 and 21, the total Salmonella in the ground beef in control packages was at 5.29 and 5.27 log CFU/g, respectively, which was significantly higher than counts in the modified atmosphere packages (3.99 to 4.31 log CFU/g on day 14 and 3.76 to 4.02 log CFU

  11. Experimental confirmation and physical understanding of ultra-high bit rate impulse radio in the THz digital communication channels of the atmosphere

    International Nuclear Information System (INIS)

    We have performed highly accurate numerical calculations of high bit rate impulse propagation through the seven digital communication channels of the atmosphere at RH 58% (10 g m−3). These calculations maximized bit rates for pathlengths equal to or longer than 100 m. We have experimentally verified our calculations for three channels with a propagation pathlength of 137 m and RH 65% (11.2 g m−3). Excellent agreement between measurement and theory was obtained for Channel 3 at 252 GHz, bit rate 84 Gb s−1, FWHM bandwidth (BW) 180 GHz; Channel 6 at 672 GHz, 45 Gb s−1, BW 84 GHz; and Channel 7 at 852 GHz, 56.8 Gb s−1, BW 108 GHz. (special issue article)

  12. El Roque de Los Muchachos Site Characteristics. III. Analysis of Atmospheric Dust and Aerosol Extinction

    CERN Document Server

    Lombardi, G; Ortolani, S; Pedani, M; Ghedina, A

    2008-01-01

    Canary Islands are normally interested by dominant North-East winds that, in some meteorological conditions, can transport sand at high altitude from the Sahara desert. The dust may affect the efficiency of the telescopes and decreases the transparency of the sky. In order to maximize the scientific return of the telescopes located at the ORM, we present an analysis of the atmospheric dust content and its effects on astronomical observations. B, V and I dust aerosol astronomical extinction are derived. Using a 5 years series database of data taken from the four channel TNG dust monitor, we compute a mean hourly and daily values of the dust content. We have detected particles having size 0.3, 0.5, 1.0 and 5.0 um. Using a power law we have derived the content of 10.0 um particles. We found a typical local dust concentration ranging from 3x10^6 particles per cubic meter at 0.3 um, to 10^3 at 5.0 um and 10 at 10.0 um, increasing up to 3 order of magnitudes during the dust storms, with a relative higher increase o...

  13. Physicochemical and Toxicological Characteristics of Semi-volatile Components of Atmospheric Aerosols in an Urban Environment

    Science.gov (United States)

    Verma, V.; Pakbin, P.; Cheung, K. L.; Cho, A. K.; Schauer, J. J.; Shafer, M. M.; Kleinman, M. T.; Sioutas, C.

    2010-12-01

    Recent toxicological studies have confirmed the oxidative properties of atmospheric aerosols and their capability to generate reactive oxygen species (ROS) in biological systems (Chen and Lippmann, 2009). While the links between aerosol toxicity and refractory transition metals present in ambient particulate matter (PM) have been documented, there are limited studies investigating the oxidative characteristics of semi-volatile species. The goal of present study is to examine the contribution of semi-volatile compounds in the oxidative potential of atmospheric aerosols. Concentrated ambient and thermodenuded quasi-ultrafine particles (dithiothreitol) assay. Detailed chemical analyses of PM samples, including organic and elemental carbon, water soluble elements, inorganic ions and polycyclic aromatic hydrocarbons (PAHs), were conducted to quantify the volatility profiles of different PM species, and also to investigate their effect on the measured oxidative potential. Refractory constituents, such as metals and elemental carbon, were marginally affected by heating, while labile species such as organic carbon and PAHs showed progressive loss in concentration with increase in TD temperature. The DTT-measured oxidative potential of PM was significantly decreased as the aerosols were heated and their semi-volatile components were progressively removed (42 %, 47 % and 66 % decrease in DTT activity at 50, 100 and 200 oC, respectively). Regression analysis performed between chemical constituents and DTT activity showed that the oxidative potential was strongly correlated with organic carbon and PAHs (R≥0.80; p≤0.05). Thus, semi-volatile organic compounds present in atmospheric aerosols constitute a substantial fraction of the PM oxidative potential, which is largely responsible for the aerosol toxicity. References: Chen, L.C., Lippmann, M., 2009. Effects of metals within ambient air particulate matter (PM) on human health. Inhalation Toxicology 21 (1), 1-31.

  14. NO emission characteristics of superfine pulverized coal combustion in the O2/CO2 atmosphere

    International Nuclear Information System (INIS)

    Highlights: • Superfine pulverized coal combustion in O2/CO2 atmosphere is a new promising technology. • NO emissions of superfine pulverized coal combustion in O2/CO2 mixture were focused. • Coal particle sizes have significant effects on NO emissions in O2/CO2 combustion. - Abstract: The combination of O2/CO2 combustion and superfine pulverized coal combustion technology can make full use of their respective merits, and solve certain inherent disadvantages of each technology. The technology of superfine pulverized coal combustion in the O2/CO2 atmosphere is easy and feasible to be retrofitted with few reconstructions on the existing devices. It will become a useful and promising method in the future. In this paper, a one-dimensional drop-tube furnace system was adopted to study the NO emission characteristics of superfine pulverized coal combustion in the O2/CO2 atmosphere. The effects of coal particle size, coal quality, furnace temperature, stoichiometric ratio, etc. were analyzed. It is important to note that coal particle sizes have significant influence on NO emissions in the O2/CO2 combustion. For the homogeneous NO reduction, smaller coal particles can inhibit the homogeneous NO formations under fuel-rich combustion conditions, while it becomes disadvantageous for fuel-lean combustion. However, under any conditions, heterogeneous reduction is always more significant for smaller coal particle sizes, which have smoother pore surfaces and simpler pore structures. The results from this fundamental research will provide technical support for better understanding and developing this new combustion process

  15. Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol

    International Nuclear Information System (INIS)

    Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure α-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images

  16. Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol

    Science.gov (United States)

    Sun, Wen-Ting; Li, Guo; Li, He-Ping; Bao, Cheng-Yu; Wang, Hua-Bo; Zeng, Shi; Gao, Xing; Luo, Hui-Ying

    2007-06-01

    Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure α-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.

  17. Atmospheric pressure chemical vapor deposition (APCVD) grown bi-layer graphene transistor characteristics at high temperature

    KAUST Repository

    Qaisi, Ramy M.

    2014-05-15

    We report the characteristics of atmospheric chemical vapor deposition grown bilayer graphene transistors fabricated on ultra-scaled (10 nm) high-κ dielectric aluminum oxide (Al2O3) at elevated temperatures. We observed that the drive current increased by >400% as temperature increased from room temperature to 250 °C. Low gate leakage was maintained for prolonged exposure at 100 °C but increased significantly at temperatures >200 °C. These results provide important insights for considering chemical vapor deposition graphene on aluminum oxide for high temperature applications where low power and high frequency operation are required. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Scintillation characteristics of annular beams propagating through atmospheric turbulence along a slanted path

    International Nuclear Information System (INIS)

    Scintillation characteristics of annular beams propagating through atmospheric turbulence along a slanted path are studied by using the numerical simulation method and some new results are obtained, which are explained in physical terms. It is found that, when the zenith angle is not large enough, the saturation phenomenon of the scintillation index never appears even if the propagation distance is large enough, which is quite different from the behavior for the horizontal propagation case. However, under the same condition (i.e. the zenith angle is not large enough), the on-axis scintillation index still approaches an asymptotical value, which increases as the zenith angle increases, and depends on the obscure ratio of annular beams. Furthermore, the relation of the on-axis scintillation index between annular beams and flat-topped beams is also examined in this paper. It is shown that their relation will change as the zenith angle changes. (paper)

  19. Dynamic and spectroscopic characteristics of atmospheric gliding arc in gas-liquid two-phase flow

    International Nuclear Information System (INIS)

    In this study, an atmospheric alternating-current gliding arc device in gas-liquid two-phase flow has been developed for the purpose of waste water degradation. The dynamic behavior of the gas-liquid gliding arc is investigated through the oscillations of electrical signals, while the spatial evolution of the arc column is analyzed by high speed photography. Different arc breakdown regimes are reported, and the restrike mode is identified as the typical fluctuation characteristic of the hybrid gliding arc in air-water mixture. Optical emission spectroscopy is employed to investigate the active species generated in the gas-liquid plasma. The axial evolution of the OH (309 nm) intensity is determined, while the rotational and vibrational temperatures of the OH are obtained by a comparison between the experimental and simulated spectra. The significant discrepancy between the rotational and translational temperatures has also been discussed.

  20. Effect on two-phase flow frictional pressure drop characteristic in narrow rectangular channel at fluctuant condition

    International Nuclear Information System (INIS)

    Based on the data of two-phase flow in narrow rectangular channel, the influence of the two-phase flow friction characteristic under the different fluctuant states was analyzed. Through analyzing the experimental data, it is shown that the fluctuant amplitude of the friction pressure drop is affected slightly by the fluctuant period in narrow rectangular channel, but the frequency of the friction pressure drop fluctuation is changed. However, the change of fluctuant period is of little effect on the average frictional pressure drop. Comparing the φl2 (φg2)-X variation curves at static condition with the ones at fluctuant condition, using the L-M method, it's found that the two phase frictional pressure drop in the narrow rectangular channel under the fluctuant state can be calculated by the φl2 (φg2)-X variation curve at static condition. (authors)

  1. Sensitivity of the biosphere-atmosphere transfer scheme (BATS) to the inclusion of variable soil characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.F.; Henderson-Sellers, A.; Dickinson, R.E.; Kennedy, P.J.

    1987-03-01

    The soils data of Wilson and Henderson-Sellers have been incorporated into the land-surface parameterization scheme of the NCAR Community Climate Model after Dickinson. A stand-alone version of this land-surface scheme, termed the Biosphere-Atmosphere Transfer Scheme (BATS), has been tested in a series of sensitivity experiments designed to assess the sensitivity of the scheme to the inclusion of variable soil characteristics. The cases investigated were for conditions designed to represent a low-latitude, evergreen forest; a low-latitude sand desert; a high-latitude coniferous forest; high-latitude tundra; and prairie grasslands, each for a specified time of year. The tundra included spring snowmelt and the grassland incorporated snow accumulation. The sensitivity experiments included varying the soil texture from a coarse texture typical of sand through a medium texture typical of loam to a fine texture typical of clay. The sensitivity of the formation to the specified total and upper soil column depth and the response to altering the parameterization of the soil albedo dependence upon soil wetness and snow-cover were also examined. The biosphere-atmosphere transfer scheme showed the greatest sensitivity to the soil texture variation, particularly to the associated variation in the hydraulic conductivity and diffusivity parameters. There was only a very small response to the change in the soil albedo dependence on wetness and, although the sensitivity to the snow-covered soil albedo via the response to roughness length/snowmasking depth was significant, the results were predictable. Soil moisture responses can also be initiated by changes in vegetation characteristics such as the stomatal resistance through changed canopy interaction which modify the radiation and water budgets of the soil surface.

  2. Characteristics of the Lower Yellow River channel shrinkage and its discriminant parameters

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper analyzes the changing trends of the Lower Yellow River(LYR) transverse profile parameters and their aberrance points by the time series analysis method.Research results show that there has been a trend of changes in the LYR channel transverse profile parameters since the 1950s.The main river channel has a tendency of shrinkage year by year and the trend will be continued in the future.The main features of the LYR channel shrinkage are remarkable reductions of bankfull dis-charges and bankfull areas,corresponding decreases of bankfull widths,average bankfull water depths and maximal bankfull water depths,as well as increases of bankfull water levels and width-depth ratios accompanied.The discriminant parameters for threshold of the LYR main channel shrinkage were put forward.It indicates that the LYR main channel began to shrink in the 1970s and has entered into a serious phase of channel shrinkage since the 1990s.The incompatible index of discharged water-sediment processes of the Sanmenxia Reservoir was introduced,which revealed that there was a trend of increasing in the incompatibility between water flow and sediment load.Response relations between the LYR main channel shrinkage parameters and discharged water-sediment processes of the Sanmenxia Reservoir were founded,which indicate that the LYR main channel shrinkage can be mitigated and improved through the regulation of discharged water-sediment processes of the reservoir,especially through the regulation of water-sediment incompatible index.The LYR channel for water and sediment transportation can be restored and maintained.

  3. The impact of quantum confinement on the electrical characteristics of ultrathin-channel GeOI MOSFETs

    International Nuclear Information System (INIS)

    The impact of quantum confinement on the electrical characteristics of ultrathin-channel GeOI n-MOSFETs is investigated on the basis of the density-gradient model in TCAD software. The effects of the channel thickness (Tch) and back-gate bias (Vbg) on the electrical characteristics of GeOI MOSFETs are examined, and the simulated results are compared with those using the conventional semi-classical model. It is shown that when Tch > 8 nm, the electron conduction path of the GeOI MOSFET is closer to the front-gate interface under the QC model than under the CL model, and vice versa when Tch < 8 nm. Thus the electrically controlled ability of the front gate of the devices is influenced by the quantum effect. In addition, the quantum-mechanical mechanism will enhance the drain-induced barrier lowering effect, increase the threshold voltage and decrease the on-state current; for a short channel length (≤ 30 nm), when Tch > 8 nm (or < 8 nm), the quantum-mechanical mechanism mainly impacts the subthreshold slope (or the threshold voltage). Due to the quantum-size effect, the off-state current can be suppressed as the channel thickness decreases. (semiconductor devices)

  4. Product Yields and Characteristics of Corncob Waste under Various Torrefaction Atmospheres

    Directory of Open Access Journals (Sweden)

    Jau-Jang Lu

    2013-12-01

    Full Text Available Biomass is a promising energy source due to its abundant, carbon-fixing, and carbon-neutral properties. Torrefaction can be employed to improve the properties of biomass in an oxygen-free or nitrogen atmosphere. This study investigates the product yields and the solid product characteristics from corncob waste torrefaction at the temperatures of 250 °C and 300 °C for 1 h. Nitrogen, carbon dioxide, and a gas mixture of air and carbon dioxide are employed as the carrier gases. The solid product characteristics approach those of coal at the higher temperature, regardless of what the carrier gases are. The fixed carbon, higher heating value, and solid and energy yields using carbon dioxide as a carrier gas at 300 °C are close to those using nitrogen. The product safety and storage properties before and after torrefaction are revealed by the measurements of ignition temperature and hygroscopicity. A higher torrefaction temperature leads to a higher ignition temperature of treated biomass, except using the mixture of air and carbon dioxide as the carrier gas. Carbon dioxide is a better carrier gas than nitrogen for biomass torrefaction, from the storage and transportation points of view.

  5. Space Charge Transient Kinetic Characteristics in DC Air Corona Discharge at Atmospheric Pressure

    Science.gov (United States)

    Liu, Xinghua; Xian, Richang; Sun, Xuefeng; Wang, Tao; Lv, Xuebin; Chen, Suhong; Yang, Fan

    2014-08-01

    Investigating the corona mechanism plays a key role in enhancing the performance of electrical insulation systems. Numerical simulation offers a better understanding of the physical characteristics of air corona discharges. Using a two-dimensional axisymmetrical kinetics model, into which the photoionization effect is incorporated, the DC air corona discharge at atmosphere pressure is studied. The plasma model is based on a self-consistent, multi-component, and continuum description of the air discharge, which is comprised of 12 species and 22 reactions. The discharge voltage-current characteristic predicted by the model is found to be in quite good agreement with experimental measurements. The behavior of the electronic avalanche progress is also described. O2+ and N2+ are the dominant positive ions, and the values of O- and O2- densities are much smaller than that of the electron. The electron and positive ion have a low-density thin layer near the anode, which is a result of the surface reaction and absorption effect of the electrode. As time progresses, the electric field increases and extends along the cathode surface, whereas the cathode fall shrinks after the corona discharge hits the cathode; thus, in the cathode sheath, the electron temperature increases and the position of its peak approaches to the cathode. The present computational model contributes to the understanding of this physical mechanism, and suggests ways to improve the electrical insulation system.

  6. Space Charge Transient Kinetic Characteristics in DC Air Corona Discharge at Atmospheric Pressure

    International Nuclear Information System (INIS)

    Investigating the corona mechanism plays a key role in enhancing the performance of electrical insulation systems. Numerical simulation offers a better understanding of the physical characteristics of air corona discharges. Using a two-dimensional axisymmetrical kinetics model, into which the photoionization effect is incorporated, the DC air corona discharge at atmosphere pressure is studied. The plasma model is based on a self-consistent, multi-component, and continuum description of the air discharge, which is comprised of 12 species and 22 reactions. The discharge voltage-current characteristic predicted by the model is found to be in quite good agreement with experimental measurements. The behavior of the electronic avalanche progress is also described. O2+ and N2+ are the dominant positive ions, and the values of O− and O2− densities are much smaller than that of the electron. The electron and positive ion have a low-density thin layer near the anode, which is a result of the surface reaction and absorption effect of the electrode. As time progresses, the electric field increases and extends along the cathode surface, whereas the cathode fall shrinks after the corona discharge hits the cathode; thus, in the cathode sheath, the electron temperature increases and the position of its peak approaches to the cathode. The present computational model contributes to the understanding of this physical mechanism, and suggests ways to improve the electrical insulation system

  7. A review of the characteristics of nanoparticles in the urban atmosphere and the prospects for developing regulatory controls

    OpenAIRE

    P. Kumar; ROBINS, A.; Vardoulakis, S; Britter, R

    2010-01-01

    The likely health and environmental implications associated with atmospheric nanoparticles have prompted considerable recent research activity. Knowledge of the characteristics of these particles has improved considerably due to an ever growing interest in the scientific community, though not yet sufficient to enable regulatory decision making on a particle number basis. This review synthesizes the existing knowledge of nanoparticles in the urban atmosphere, highlights recent advances in our ...

  8. Characteristics of the steady-state flow of a two-temperature argonarc plasma in a channel

    International Nuclear Information System (INIS)

    The authors examine the effects of laminar and turbulent flow on the characteristics of two-temperature argon plasma in the steady state part of an electric arc in a cylindrical channel; they examine existing formulas for the plasma properties and have selected for use here those that agree best with the experiment. This work has been done because design of high-temperature gas heaters with given characteristics is hindered by the lack of applicable models closely adapted to real conditions, this applying particularly to electric-arc plasma sources that produce thermally nonequilibrium plasma

  9. Impact of vegetation density on flow characteristics in a straight compound channel

    International Nuclear Information System (INIS)

    Vegetation exists on the floodplains of almost all natural channels. This vegetation results in a number of changes in flow features of open channel flows. Sometimes vegetation also exists within the main channel. This paper presents a numerical study in which the impact of vegetation density on different flow features has been considered. The variables investigated included velocity profiles, bed shear stresses, Reynolds stresses and side wall shear stresses. A compound channel with floodplain on both sides of the main channel has been considered. Four different vegetation densities were considered in this work. It was revealed that increase in vegetation density results in a decrease in the velocity values close to the bed and in the upper regions of the flood plains. The Reynolds stresses were also influenced considerably in the lower regions of the channel. Similar patterns were observed in case of bed shear stresses. The vertical profiles of side wall shear stresses were also investigated in this work. Such an investigation will help in enhancing the understanding and improving different conveyance and flow resistance calculation formulae. (author)

  10. Characteristics of a Miocene intrabank channel in Batu Raja limestone, Ramba field, south Sumatra, Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Longman, M.W.; Maxwell, R.J.; Mason, A.D.M.; Beddoes, L.R. Jr.

    1987-10-01

    Ramba field in the South Sumatra basin produces oil from lower Miocene coral and foraminifera-rich wackestones with secondary moldic and vuggy porosity. These wackestones form two low-relief carbonate banks separated by a deeper water, intrabank channel at least 10 km long and 1 km wide. Sediments infilling the channel include (1) carbonate mudstone, (2) carbonate conglomerate (calclithite) composed of dolomite and micrite intraclasts, (3) foraminiferal packstone to grainstone, and (4) terrigenous shale rich in planktonic foraminifera. The channel formed during fault-controlled down-warping during (or followed by) growth of the adjacent carbonate banks. Slow rates of carbonate deposition in the clay-rich environment of the channel resulted in deposition of relatively tight carbonates that form a nonproductive barrier between the A and B oil pools in Ramba field. The channel-fill deposits are economically important for two reasons: (1) where tight, they act as a lateral seal to the reservoir, and (2) the carbonate conglomerate has sufficient porosity and permeability to have provided the spillpoint for oil in the A pool. Thus, although not sufficiently permeable to provide commercial production, it is the distribution of this conglomerate in the channel that limits the height of the oil column in the Ramba field's A pool to only 48 m. 12 figures.

  11. Measurement and statistical analysis of the wavefront distortions induced by atmospheric turbulence using two-channel moiré deflectometry

    International Nuclear Information System (INIS)

    Recently, an adjustable, high-sensitivity, wide dynamic range, two-channel wavefront sensor based on moiré deflectometry was proposed by Rasouli et al (2010 Opt. Express 18 23906). In this work we have used this sensor on a telescope for measuring turbulence-induced wavefront distortions. A slightly divergent laser beam passes through turbulent ground level atmosphere and enters the telescope’s aperture. The laser beam is collimated behind the telescope’s focal point by means of a collimator and the beam enters the wavefront sensor. First, from deviations in the moiré fringes we calculate the two orthogonal components of the angle of arrival at each location across the wavefront. The deviations have been deduced in successive frames which allows evolution of the wavefront shape and Fried’s seeing parameter r0 to be determined. Mainly, statistical analysis of the reconstructed wavefront distortions are presented. The achieved accuracy in the measurements and comparison between the measurements and the theoretical models are presented. Owing to the use of the sensor on a telescope, and using sub-pixel accuracy for the measurement of the moiré fringe displacements, the sensitivity of the measurements is improved by more than one order of magnitude. In this work we have achieved a minimum measurable angle of arrival fluctuations equal to 3.7 × 10−7 rad or 0.07 arc s. Besides, because of the large area of the telescope’s aperture, a high spatial resolution is achieved in detecting the spatial perturbations of the atmospheric turbulence. (paper)

  12. Role of the atmospheric mean state on the initiation of the Madden-Julian oscillation in a tropical channel model

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Pallav; Zhang, Chidong [University of Miami, RSMAS/MPO, Miami, FL (United States); Moncrieff, Mitchell W.; Dudhia, Jim; Caron, Julie M.; Bruyere, Cindy [National Center for Atmospheric Research, Boulder, CO (United States); Ruby Leung, L. [Pacific Northwest National Laboratory, Richland, WA (United States)

    2011-01-15

    Tropical channel models, defined as models that are global in the zonal direction but bounded in the meridional direction, are particularly useful for simulating the Madden-Julian oscillation (MJO) and understanding its physical and dynamical basis. Influences from the extratropics through the lateral boundaries have been found to be essential to the reproduction of the initiation of certain MJO events. This led to a hypothesis that multi-year simulations using a tropical channel model would reproduce reasonable MJO statistics under the influence of prescribed lateral boundary conditions derived from global reanalyses. Interestingly, the MJO statistics in such a multi-year simulation by a high-resolution tropical channel model are not better than those from global climate models. The error in the atmospheric mean state is found to be a possible reason for the poor MJO statistics in the simulation. Nevertheless, even with a large error in the mean state, the multi-year simulation captures two MJO events previously found to be initiated by extratropical influences. However, the model does not reproduce a third event, whose initiation is not directly influenced by the extratropics. This implies that in the absence of dynamical interactions between the MJO and the lateral boundary conditions, the error in the mean state could be sufficient to prevent the MJO initiation. To explore this third MJO event further, a series of sensitivity tests are conducted. These tests show that the simulation of this event is neither critically influenced by the cumulus parameterization employed, nor the initial conditions when the model is integrated 2 weeks prior to the MJO initiation. The model captures this event when the MJO signal is already present in the initial conditions. The use of high-resolution sea surface temperature does not improve the simulation of the third MJO event. A higher-resolution nested domain covering the Indo-Pacific warm pool region and including a cloud

  13. Role of the Atmospheric Mean State on the Initiation of the Madden-Julian Oscillation in a Tropical Channel Model

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Pallav; Zhang, Chidong; Moncrieff, Mitch; Dudhia, Jimy; Caron, Julie M.; Leung, Lai-Yung R.; Bruyere, Cindy

    2010-06-08

    Tropical channel models, defined as models that are global in the zonal direction but bounded in the meridional direction, are particularly useful for simulating the Madden-Julian oscillation (MJO) and understanding its physical and dynamical basis. Influences from the extratropics through the lateral boundaries have been found to be essential to the reproduction of the initiation of certain MJO events. This led to a hypothesis that multi-year simulations using a tropical channel model would reproduce reasonable MJO statistics under the influence of prescribed lateral boundary conditions derived from global reanalyses. Interestingly, the MJO statistics in such a multi-year simulation by a high-resolution tropical channel model are not better than those from global climate models. The error in the atmospheric mean state is found to be a possible reason for the poor MJO statistics in the simulation. Nevertheless, even with a large error in the mean state, the multi-year simulation captures two MJO events previously found to be initiated by extratropical influences. However, the model does not reproduce a third event, whose initiation is not directly influenced by the extratropics. This implies that in the absence of dynamical interactions between the MJO and the lateral boundary conditions, the error in the mean state could be sufficient to prevent the MJO initiation. To explore this third MJO event further, a series of sensitivity tests are conducted. These tests show that the simulation of this event is neither critically influenced by the cumulus parameterization employed, nor the initial conditions when the model is integrated 2 weeks prior to the MJO initiation. The model captures this event when the MJO signal is already present in the initial conditions. The use of highresolution sea surface temperature does not improve the simulation of the third MJO event. A higher-resolution nested domain covering the Indo-Pacific warm pool region and including a cloud

  14. On the characteristics of atmospheric circulation associated with snowfall in NW Greece

    Science.gov (United States)

    Houssos, E. E.; Lolis, C. J.; Bartzokas, A.

    2009-09-01

    matrix in order to objectively classify the 235 atmospheric structures associated with snowfall in Ioannina (NW Greece) into 9 homogeneous and distinct clusters. The optimum number of clusters is decided by using the "Jump" method, first described by Sugar and James. For each cluster the mean maps of the initial 3 meteorological parameters (MSL pressure, T-850hPa and Z-500hPa) are constructed revealing the main characteristics of the atmospheric structure during snowfall events in NW Greece. According to the main results, snowfall in NW Greece is associated with a low pressure system around Greece combined with an anticyclone over W or NW Europe, causing cold northwesterly flow over NW Greece. In the upper atmosphere, a deep 500hPa trough usually extends from W Russia to Italy and the Ionian Sea. The main differences among the 9 atmospheric structures revealed are found in the exact location of the centres of the low pressure system and the anticyclone and the exact direction of the trough axis. The final stage is an attempt to investigate whether a situation similar to one of the 9 atmospheric structures, causes snowfall in NW Greece. For this reason all the available meteorological maps were compared to the 9 created mean maps (in fact each case consists of a set of 3 maps, viz. MSL pressure, T-850, Z500). The comparisons were made by calculating the correlation coefficient between the space series of the anomalies of each case with the space series of the anomalies of the 9 mean maps. It was found that a considerable number of cases without snowfall in Ioannina are correlated well with the maps of snowfall. This can be explained by the fact that there are very many cases just before or just after snowfall in Ioannina which present an atmospheric structure very similar with the one during snowfall. Also, a couple of degrees of temperature difference may confine snowfall in higher altitudes and cause rainfall in Ioannina. Finally, it is obvious that the results would be

  15. Characteristics-Based Methods for Efficient Parallel Integration of the Atmospheric Dynamical Equations

    Science.gov (United States)

    Norman, Matthew Ross

    The social need for realistic atmospheric simulation in weather prediction, climate change attribution, seasonal forecasting, and climate projection is great. To obtain realistic simulations, we need more physical processes included in the model with greater fidelity and finer spatial resolution. Spatial resolution primarily drives the need for computational resources because reducing the model grid spacing by a factor f requires f 4 times more computation (assuming 3-D refinement). This compute power comes from large parallel machines with 10,000s of separate nodes and accelerators such as graphics processing units (GPUs) making efficiency a complicated problem. Efficiency parallel integration algorithms need low internode communication, minimal synchronization, large time steps, and clustered computation. To this end, we propose new characteristics-based methods for the atmospheric dynamical equations with these properties in mind. These schemes are capable of simulating at a large CFL time step in only one stage of computations, needing only one copy of the state variables. They are implemented in a 2-D non-hydrostatic compressible equation set in an x-z (horizontal-vertical) Cartesian plane to simulate buoyancy-driven flows such as rising thermals and internal gravity waves. The schemes are implemented to run on CPU and multi-GPU architectures using Nvidia's CUDA (Compute Unified Device Architecture) language to test relative efficiency. Even with- out memory tuning, the GPU code showed roughly 2.5x (5x) better performance per Watt. With optimization, this could increase by an order of magnitude. The methods can use any spatial interpolant, so two major formulations are proposed and tested. One uses WENO interpolants which are pre-computed, and the other uses standard polynomials and computes them on-the-fly. The advantage of on-the-fly calculations is a significant reduction in the volume of data communicated to and from the GPU's slow global memory. In some

  16. Atmospheric Circulation Characteristics Associated with the Onset of Asian Summer Monsoon

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The onset of the Asian summer monsoon has been a focus in the monsoon study for many years. In this paper, we study the variability and predictability of the Asian summer monsoon onset and demonstrate that this onset is associated with specific atmospheric circulation characteristics. The outbreak of the Asian summer monsoon is found to occur first over the southwestern part of the South China Sea (SCS)and the Malay Peninsula region, and the monsoon onset is closely related to intra-seasonal oscillations in the lower atmosphere. These intra-seasonal oscillations consist of two low-frequency vortex pairs, one located to the east of the Philippines and the other over the tropical eastern Indian Ocean. Prior to the Asian summer monsoon onset, a strong low-frequency westerly emerges over the equatorial Indian Ocean and the low-frequency vortex pair develops symmetrically along the equator. The formation and evolution of these low-frequency vortices are important and serve as a good indicator for the Asian summer monsoon onset. The relationship between the northward jumps of the westerly jet over East Asia and the Asian summer monsoon onset over SCS is investigated. It is shown that the northward jump of the westerly jet occurs twice during the transition from winter to summer and these jumps are closely related to the summer monsoon development. The first northward jump (from 25°-28°N to around 30°N) occurs on 8 May on average, about 7 days ahead of the summer monsoon onset over the SCS. It is found that the reverse of meridional temperature gradient in the upper-middle troposphere (500-200 hPa) and the enhancement and northward movement of the subtropical jet in the Southern Hemispheric subtropics are responsible for the first northward jump of the westerly jet.

  17. Synoptic-scale characteristics and atmospheric controls of summer heat waves in China

    Science.gov (United States)

    Wang, Weiwen; Zhou, Wen; Li, Xiuzhen; Wang, Xin; Wang, Dongxiao

    2016-05-01

    Summer heat waves with persistent extreme high temperatures have been occurring with increasing frequency in recent decades. These extreme events have disastrous consequences for human health, economies, and ecosystems. In this study, we examine three summers with intense and protracted heat waves: the summers of 2003, 2006, and 2013, with high temperatures located mainly in southeastern, southwestern, and eastern China, respectively. The synoptic-scale characteristics of these heat waves and associated atmospheric circulation anomalies are investigated. In the early heat wave episode of 2003, a heat center was located in the southeast coastal provinces during the first 20 days of July. The maximum southward displacement of the East Asian jet stream (EAJS) induced anticyclonic anomalies to the south, associated with southwestward intensification of the western North Pacific subtropical high (WNPSH), and extreme high temperatures were found only to the south of the Yangtze River. In the later episode, a poleward displacement of the EAJS and an enhanced WNPSH over the midlatitudes of eastern China resulted in a "heat dome" over the region, and the heat wave extended northward to cover a larger area of eastern China. The coupling between the westward-enhanced WNPSH and poleward-displaced EAJS was found in the East China heat wave of 2013 as well. But the area of high temperatures reached far to the north in August 2013, with below-normal temperatures located in a small region of South China. In the 2006 southwestern drought and heat wave, extreme poleward displacement of the EAJS, associated with extraordinary westward extension of the WNSPH, resulted in further blocking of the moisture supply from the southwest monsoon. Large-scale moisture deficiencies, dry conditions, and downslope winds were common features of all investigated heat wave episodes. But in 2006, low-level heat lows associated with a well-mixed layer due to intensive daytime heating and atmospheric

  18. Change characteristic of atmospheric particulate mercury during dust weather of spring in Qingdao, China

    Science.gov (United States)

    Zhang, Yuqing; Liu, Ruhai; Wang, Yan; Cui, Xueqing; Qi, Jianhua

    2015-02-01

    Atmospheric aerosol samples were collected during dust weather of spring from 2008 to 2011 in Qingdao, in which the concentrations of atmospheric particulate mercury (PHg) were measured to analyze its distribution characteristics and source. PHg concentration during the study ranged from 0.050 ng m-3 to 0.788 ng m-3 with the average 0.292 ng m-3 in dust day, while 0.085 ng m-3 to 0.444 ng m-3 with the average 0.188 ng m-3 in non-dust day. PHg concentration in dust day is far higher than that in some cities of South Korea and Japan and comparable to some cities in China. There was a statistically power function between PHg/TSP and TSP concentrations, which meant that intense dust (high TSP) brought particles with low mercury content. The estimated dry deposition flux of PHg is 0.9-14.2 ng m-2 h-1 with the mean 5.26 ng m-2 h-1 in dust day. The mercury deposition flux in a dust day accounts for almost 1% annual flux, which should be paid attention in the regional and global cycle of mercury. The trajectories are categorized into 4 sectors. Cluster 1 and cluster 4 were the main routes of dust to Qingdao, coming from Kazakhstan and north of Mongolia individually. There is higher TSP, and lower PHg/TSP in dust of cluster 4 compared with cluster 1, because of longer transport distance and faster movement speed. There is highest PHg/TSP in cluster 2 because of passing polluted East China. The slow transport speed, long stay at polluted developed region caused pollutants to accumulate in the aerosols. Differences of transport route, movement speed affects the mercury content significantly.

  19. FAST TRACK COMMUNICATION: Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

    Science.gov (United States)

    Walsh, J. L.; Liu, D. X.; Iza, F.; Rong, M. Z.; Kong, M. G.

    2010-01-01

    Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O2 by helium metastables is significantly more efficient than electron dissociative excitation of O2, electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O2 plasmas for excited atomic oxygen based chemistry.

  20. Experimental research of flow boiling heat transfer characteristics in narrow channel

    International Nuclear Information System (INIS)

    Based on the experimental data of boiling heat transfer in narrow rectangular channel with a cross section of 40 mm · 2 mm, the main factors that impact the position of fully developed boiling (FDB) and boiling heat transfer coefficient were analyzed, then the experimental data and the calculated values were compared. The position of FDB obtained by experiment agrees well with the value predicted by Bowring correlation and Saha-Zuber correlation, and the relative deviation is within 20%. The boiling heat transfer coefficient acquired by experiment in narrow rectangular channel was compared with Chen correlation. Gungor-Winterton correlation and Sun Licheng correlation. The results indicate that the Chen correlation applied to conventional channel is not suitable for predicting the boiling heat transfer coefficient in narrow rectangular channel. While the Sun Licheng correlation considering the effect of narrow channel size and regarding the heat flux as the main function in boiling heat transfer can predict the experimental results well, and the relative deviation of the correlation and experiment is within 30%. (authors)

  1. Characteristics of particulate radionuclides in the atmospheric surface layer of the 30-km zone of Chernobyl

    International Nuclear Information System (INIS)

    For the inhalation dose assessment, reliable estimations are necessary of the average volume concentration of particle bound radionuclides in the atmosphere specifying the nuclide composition, the activity distribution in the different particle size ranges and the solubility characteristics of the nuclides. For that purpose, the analysis of measurement series is presented of the daily average activity concentrations of 137Cs and 144Ce and their temporal and spatial variability. From 1986 till 1994, samples were taken with high-volume samplers and multicascade impactors; the number concentrations of aerosol particles and the number concentrations of 'hot' particles were determined for different conditions with an Aerosol Particle Sizer and a Rotating Arm Impactor. The data demonstrate a decrease the atmospheric concentrations of 137Cs and 144Ce with time larger than caused by radioactive decay alone. A statistical analysis showed a high level of fluctuations in the concentration of radionuclides in air with maxima exceeding the annual average by 10 to 20 times. The analysis of 88 experimental radioactivity size distributions at Zapolie and Pripyat for winddriven resuspension conditions have shown that the measured distributions are generally very wide and differ from the log-normal distribution in the most cases. At Zapolie, the mean air concentrations of 137Cs, discriminated in four size ranges, showed an increasing part of inhalable particles with time since the accident. In 1993, the inhalable fraction was about 48% of the total concentration. The size distribution of atmospheric 137Cs particulate activity during these periods of enhanced resuspension showed a similar common shape with two maxima, the first in the 2-4 μm range, and the second in the 12-20 μm range. The estimated radioactive loading of particles showed an enrichment of resuspended radionuclides compared with soil particles. The highest enrichment factor was found for large particles, the lowest

  2. Multi-DSP and FPGA based Multi-channel Direct IF/RF Digital receiver for atmospheric radar

    Science.gov (United States)

    Yasodha, Polisetti; Jayaraman, Achuthan; Kamaraj, Pandian; Durga rao, Meka; Thriveni, A.

    2016-07-01

    Modern phased array radars depend highly on digital signal processing (DSP) to extract the echo signal information and to accomplish reliability along with programmability and flexibility. The advent of ASIC technology has made various digital signal processing steps to be realized in one DSP chip, which can be programmed as per the application and can handle high data rates, to be used in the radar receiver to process the received signal. Further, recent days field programmable gate array (FPGA) chips, which can be re-programmed, also present an opportunity to utilize them to process the radar signal. A multi-channel direct IF/RF digital receiver (MCDRx) is developed at NARL, taking the advantage of high speed ADCs and high performance DSP chips/FPGAs, to be used for atmospheric radars working in HF/VHF bands. Multiple channels facilitate the radar t be operated in multi-receiver modes and also to obtain the wind vector with improved time resolution, without switching the antenna beam. MCDRx has six channels, implemented on a custom built digital board, which is realized using six numbers of ADCs for simultaneous processing of the six input signals, Xilinx vertex5 FPGA and Spartan6 FPGA, and two ADSPTS201 DSP chips, each of which performs one phase of processing. MCDRx unit interfaces with the data storage/display computer via two gigabit ethernet (GbE) links. One of the six channels is used for Doppler beam swinging (DBS) mode and the other five channels are used for multi-receiver mode operations, dedicatedly. Each channel has (i) ADC block, to digitize RF/IF signal, (ii) DDC block for digital down conversion of the digitized signal, (iii) decoding block to decode the phase coded signal, and (iv) coherent integration block for integrating the data preserving phase intact. ADC block consists of Analog devices make AD9467 16-bit ADCs, to digitize the input signal at 80 MSPS. The output of ADC is centered around (80 MHz - input frequency). The digitized data is fed

  3. Influence of BCH and LDPC Code Parameters on the BER Characteristic of Satellite DVB Channels

    Directory of Open Access Journals (Sweden)

    L. Jordanova

    2014-02-01

    Full Text Available This article presents the results of a study on the noise immunity of DVB channels when higher-order M-ary APSK modulation schemes and concatenated BCH-LDPC codes are used. Dependencies to determine the probability at the decoder output are given taking into consideration the BCH and LDPC code parameters and the error probability in the communication channel. The influence of the BCH packets length, the BCH code rate, the number of maximum iteration and the parameters of LDPC parity-check matrix on the code efficiency is analyzed. Research of the influence of the concatenated LDPC-BCH code parameters on the radio channel noise immunity is conducted and dependencies to determine the required CNR at the input of the satellite receiver are given.

  4. Characteristics of turbulent velocity and temperature in a wall channel of a heated rod bundle

    Energy Technology Data Exchange (ETDEWEB)

    Krauss, T.; Meyer, L. [Forschungszentrum Karlsruhe (Germany)

    1995-09-01

    Turbulent air flow in a wall sub-channel of a heated 37-rod bundle (P/D = 1.12, W/D = 1.06) was investigated. measurements were performed with hot-wire probe with X-wires and a temperature wire. The mean velocity, the mean fluid temperature, the wall shear stress and wall temperature, the turbulent quantities such as the turbulent kinetic energy, the Reynolds-stresses and the turbulent heat fluxes were measured and are discussed with respect to data from isothermal flow in a wall channel and heated flow in a central channel of the same rod bundle. Also, data on the power spectral densities of the velocity and temperature fluctuations are presented. These data show the existence of large scale periodic fluctuations are responsible for the high intersubchannel heat and momentum exchange.

  5. Two phase pressure drop characteristics in rectangular channel with low aspect ratio

    International Nuclear Information System (INIS)

    The study on two phase pressure drop in rectangular channel with low aspect ratio (0.05) was carried on using water. The state-of-art correlations failed to satisfactorily predict the experimental data. The dimensionless Nconf, can account for the maximum size of the bubble confined in small channel during flow boiling process. The data were used to develop a new correlation based on Lockhart-Martinelli method with Nconf. The correlation is tested against the experimental data, and the relative deviation is in ±15%. (authors)

  6. Modelling some characteristics of electrical networks used as channels for providing telecommunications

    Directory of Open Access Journals (Sweden)

    Henry Arturo Bastidas Mora

    2010-07-01

    Full Text Available This article describes the topology of the existent electric nets in different parts of the world, included the Colombian nets, and there performance when used as telecommunications channels. The transfer function is analyzed for low tension nets and radiation originated by PLC (Power Line Communications technology is also considered. Since the radiation originated by PLC cannot be avoided completely the effect electromagnetic interference will be described with radio frequency communications. Modeling of the PLC channel is proposed and at the end conclusions are presented.

  7. RF and microwave characteristics of a 10 nm thick InGaN-channel gate recessed HEMT

    International Nuclear Information System (INIS)

    A new depletion-mode gate recessed AlGaN/InGaN/GaN-high electron mobility transistor (HEMT) with 10 nm thickness of InGaN-channel is proposed. A growth of AlGaN over GaN leads to the formation of two-dimensional electron gas (2DEG) at the heterointerface. High 2DEG density (ns) is achieved at the heterointerface due to a strain induced piezoelectric effect between AlGaN and GaN layers. The electrons are confined in the InGaN-channel without spilling over into the buffer layer, which also reduces the buffer leakage current. From the input transfer characteristics the threshold voltage is obtained as −4.5 V and the device conducts a current of 2 A/mm at a drain voltage of 10 V. The device also shows a maximum output current density of 1.8 A/mm at Vds of 3 V. The microwave characteristics like transconductance, cut-off frequency, max frequency of oscillation and Mason's Unilateral Gain of the device are studied by AC small-signal analysis using a two-port network. The stability and power performance of the device are analyzed by the Smith chart and polar plots respectively. To our knowledge this proposed InGaN-channel HEMT structure is the first of its kind. (semiconductor devices)

  8. Characteristics pertinent to propagation of pulsating pressure in the channels of turbine machines

    Science.gov (United States)

    Liu, Hong; Chen, Zuoyi

    2007-01-01

    A new model describing the propagation of the pressure pulsations in the intricately shaped channels of turbine machines is presented. The proposed model was successfully used to analyze two emergency events: a failure of a steam turbine’s cast diaphragm and a failure of a rocket engine’s oxygen pump booster stage.

  9. Characterization of potassium channel modulators with QPatch automated patch-clamp technology: system characteristics and performance

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Friis, Søren; Asmild, Margit;

    2003-01-01

    -cell configurations lasted for >20 min. Cells were maintained in suspension up to 4 h in a cell storage facility that is integrated in the QPatch 16. No decline in patchability was observed during this time course. A series of screens was conducted with known inhibitors of the hERG and KCNQ4 potassium channels. Dose...

  10. Approximation characteristic between LEMP on earth surface and channel-base current

    International Nuclear Information System (INIS)

    Based on the dipole technique, the exact expressions and approximate expressions for LEMP on earth surface are derived from the TL model and specified channel-base current described by a pulse function. According to the comparisons between the exact results and approximate results, the waveforms of LEMP and its derivative are similar to the lightning channel-base current and its derivative, respectively. In near-field, the electric field and its derivative waveforms of the approximate results are essentially coincident with the corresponding waveforms of the exact results within 100 m. The magnetic field waveforms of approximate results are essentially coincident with the waveforms of the exact results within 500 m, and the magnetic field derivative waveforms of the approximate results are essentially coincident with the waveforms of the exact results within 200 m. In far-field, the waveforms of the approximate results are essentially coincident with the waveforms of the exact results in the rising edge before the initial peak value. At the distance beyond 100 km, the waveforms of the radiation field component and the scaled channel-base current appear identical. The difference between the derivative waveforms of the LEMP field and the scaled channel-base current in the first three microseconds is slight and can be ignored.

  11. Distribution Characteristics, Concentrations, and Sources of Cd and Pb in Laoxiawan Channel Sediments from Zhuzhou, China.

    Science.gov (United States)

    Chen, Wen-Wen; Zhang, Jian-Xin; Abass, Olusegun-Kazeem; Wen, Xin-Yu; Huang, Huan-Fang; Qu, Cheng-Kai; Qi, Shi-Hua

    2016-06-01

    Twenty sediment cores encompassing surface (0-20 cm) and deeper (50-60 cm) sediment layers were retrieved from the 3000 m-long Laoxiawan Channel, which receives industrial effluents from Zhuzhou City (China). Analytical results showed that cadmium (Cd) concentrations ranged between 115.7-1126.7 and 108.8-2059.3 mg/kg while lead (Pb) values ranged between 234-3000 and 145-4292 mg/kg in the surface and bottom sediments, respectively. The results also indicated that high levels of Cd and Pb were present in the vicinity of the channel mouth and confluence area. Indices for potential ecological risk and geo-accumulation were used to evaluate the environmental effects and intensity of heavy metal pollution over time. High concentrations of Cd and Pb in the bottom sediments of Laoxiawan Channel were mainly associated with wastewater discharge (10(6) m(3)/year). Thus, the Laoxiawan Channel may be an important metal contaminant source for the Xiang River. PMID:27025765

  12. Aging Characteristics on Epoxy Resin Surface Under Repetitive Microsecond Pulses in Air at Atmospheric Pressure

    Science.gov (United States)

    Xie, Qing; Liu, Xiong; Zhang, Cheng; Wang, Ruixue; Rao, Zhangquan; Shao, Tao

    2016-03-01

    Research on aging characteristics of epoxy resin (EP) under repetitive microsecond pulses is important for the design of insulating materials in high power apparatus. It is because that very fast transient overvoltage always occurs in a power system, which causes flashover and is one of the main factors causing aging effects of EP materials. Therefore, it is essential to obtain a better understanding of the aging effect on an EP surface resulting from flashover. In this work, aging effects on an EP surface were investigated by surface flashover discharge under repetitive microsecond pulses in atmospheric pressure. The investigations of parameters such as the surface micro-morphology and chemical composition of the insulation material under different degrees of aging were conducted with the aid of measurement methods such as atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Results showed that with the accumulation of aging energy on the material surface, the particles formed on the material surface increased both in number and size, leading to the growth of surface roughness and a reduction in the water contact angle; the surface also became more absorbent. Furthermore, in the aging process, the molecular chains of EP on the surface were broken, resulting in oxidation and carbonisation. supported by the Natural Science Foundation of Hebei Province (No. E2015502081), National Natural Science Foundation of China (Nos. 51222701, 51307060), and the National Basic Research Program of China (No. 2014CB239505-3)

  13. A Study On Atmospheric Boundary-Layer Characteristics At Anand, India Using Lsp Experimental Data Sets

    Science.gov (United States)

    Satyanarayana, A. N. V.; Lykossov, V. N.; Mohanty, U. C.

    An attempt is made to study the planetary boundary layer (PBL) characteristics during the winter period at Anand (22.4°N, 72.6°E), a semi-arid region, which is located in the western part of India. A one-dimensional turbulent kinetic energy (TKE) closure model is used for the study. The structure of the PBL,which consists of profiles of zonal and meridional components of wind,potential temperature and specific humidity, is simulated. A one-dimensional soil heat and moisture transport parameterization scheme is incorporated for the accurate representation of the energy exchange processes at the soil-atmosphere interface. The diurnal variation of fluxes of sensible heat, latent heat, shortwave radiation, net radiation and soil flux, soil temperature at different depths, Richardson number and TKE at the height of the constant flux layer is studied. The model predictions are compared with the available observations obtained from a special Land Surface Processes (LSP) experiment.

  14. Product characteristics from the torrefaction of oil palm fiber pellets in inert and oxidative atmospheres.

    Science.gov (United States)

    Chen, Wei-Hsin; Zhuang, Yi-Qing; Liu, Shih-Hsien; Juang, Tarng-Tzuen; Tsai, Chi-Ming

    2016-01-01

    The aim of this work was to study the characteristics of solid and liquid products from the torrefaction of oil palm fiber pellets (OPFP) in inert and oxidative environments. The torrefaction temperature and O2 concentration in the carrier gas were in the ranges of 275-350°C and 0-10 vol%, respectively, while the torrefaction duration was 30 min. The oxidative torrefaction of OPFP at 275°C drastically intensified the HHV of the biomass when compared to the non-oxidative torrefaction. OPFP torrefied at 300°C is recommended to upgrade the biomass, irrespective of the atmosphere. The HHV of condensed liquid was between 10.1 and 13.2 MJ kg(-)(1), and was promoted to 23.2-28.7 MJ kg(-)(1) following dewatering. This accounts for 92-139% improvement in the calorific value of the liquid. This reveals that the recovery of condensed liquid with dewatering is able to enhance the energy efficiency of a torrefaction system. PMID:26346262

  15. Characteristics of the near-surface atmosphere over the Ross Ice Shelf, Antarctica

    Science.gov (United States)

    Cassano, John J.; Nigro, Melissa A.; Lazzara, Matthew A.

    2016-04-01

    Two years of data from a 30 m instrumented tower are used to characterize the near-surface atmospheric state over the Ross Ice Shelf, Antarctica. Stable stratification dominates the surface layer at this site, occurring 83% of the time. The strongest inversions occur for wind speeds less than 4 m s-1 and the inversion strength decreases rapidly as wind speed increases above 4 m s-1. In summer unstable stratification occurs 50% of the time and unstable conditions are observed in every season. A novel aspect of this work is the use of an artificial neural network pattern identification technique, known as self-organizing maps, to objectively identify characteristic potential temperature profiles that span the range of profiles present in the 2 year study period. The self-organizing map clustering technique allows the more than 100,000 observed potential temperature profiles to be represented by just 30 patterns. The pattern-averaged winds show distinct and physically consistent relationships with the potential temperature profiles. The strongest winds occur for the nearly well mixed but slightly stable patterns and the weakest winds occur for the strongest inversion patterns. The weakest wind shear over the depth of the tower occurs for slightly unstable profiles and the largest wind shear occurs for moderately strong inversions. Pattern-averaged log wind profiles are consistent with theoretical expectations. The log wind profiles exhibit a kinked profile for the strongest inversion cases indicative of decoupling of the winds between the bottom and top of the tower.

  16. Spatial characteristics of airglow and solar-scatter radiance from the earth's atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Huguenin, R.; Wohlers, R.; Weinberg, M.; Huffman, R.; Eastes, R.

    1989-08-09

    Data measured by the Polar BEAR/AIRS UV Experiment were processed to extract spatial-radiance characteristics. Photometer-mode 1304A dayside data measured on Julian Day 219, 1987, near mid-day were analyzed. The spatial structure of thermospheric dayside radiance at 1304A appeared to be controlled principally by turbulence over spatial scales of 10 million - 100 meters, with modifications imposed by Rayleigh-scattering effects and magnetospherically forced phenomena. Spatial structure can be adequately modeled fractally, using dimensions based on Kolmogorov formalism modified by the Rayleigh scattering phase function. Mean radiance can be modeled using existing models of radiant intensity, resonance scattering, and absorption combined with thermospheric composition and general circulation models, such as MSIS-83, scaled to the mean and RHS intensities measured by Polar BEAR. The results can be incorporated in a background radiance simulation model that will provide a means for testing and refining phenomenological models of the structured earth background. This will be important not only for improving physical and chemical models of atmospheric features and processes, but it will allow parametric predictions of spatial structure and clutter to be developed for sensor applications.

  17. The first discovered water channel protein, later called aquaporin 1: molecular characteristics, functions and medical implications.

    Science.gov (United States)

    Benga, Gheorghe

    2012-01-01

    After a decade of work on the water permeability of red blood cells (RBC) Benga group in Cluj-Napoca, Romania, discovered in 1985 the first water channel protein in the RBC membrane. The discovery was reported in publications in 1986 and reviewed in subsequent years. The same protein was purified by chance by Agre group in Baltimore, USA, in 1988, who called in 1991 the protein CHIP28 (CHannel forming Integral membrane Protein of 28 kDa), suggesting that it may play a role in linkage of the membrane skeleton to the lipid bilayer. In 1992 the Agre group identified CHIP28's water transport property. One year later CHIP28 was named aquaporin 1, abbreviated as AQP1. In this review the molecular structure-function relationships of AQP1 are presented. In the natural or model membranes AQP1 is in the form of a homotetramer, however, each monomer has an independent water channel (pore). The three-dimensional structure of AQP1 is described, with a detailed description of the channel (pore), the molecular mechanisms of permeation through the channel of water molecules and exclusion of protons. The permeability of the pore to gases (CO(2), NH(3), NO, O(2)) and ions is also mentioned. I have also reviewed the functional roles and medical implications of AQP1 expressed in various organs and cells (microvascular endothelial cells, kidney, central nervous system, eye, lacrimal and salivary glands, respiratory apparatus, gastrointestinal tract, hepatobiliary compartments, female and male reproductive system, inner ear, skin). The role of AQP1 in cell migration and angiogenesis in relation with cancer, the genetics of AQP1 and mutations in human subjects are also mentioned. The role of AQP1 in red blood cells is discussed based on our comparative studies of water permeability in over 30 species. PMID:22705445

  18. Estimate of the largest Lyapunov characteristic exponent of a high dimensional atmospheric global circulation model: a sensitivity analysis

    International Nuclear Information System (INIS)

    In this report the largest Lyapunov characteristic exponent of a high dimensional atmospheric global circulation model of intermediate complexity has been estimated numerically. A sensitivity analysis has been carried out by varying the equator-to-pole temperature difference, the space resolution and the value of some parameters employed by the model. Chaotic and non-chaotic regimes of circulation have been found.

  19. Characteristic turbulent structure of a modified drag-reduced surfactant solution flow via dosing water from channel wall

    International Nuclear Information System (INIS)

    Highlights: • Modulation of near wall turbulence was conducted on a viscoelastic drag-reduced flow. • Flow of coexisting Newtonian and non-Newtonian fluids was realized. • Drag reduction is enhanced, although the Reynolds shear stress increases. • An obvious regional characteristic structure is presented. • Anisotropy of near-wall turbulence was discussed. - Abstract: The modification of the near-wall structure is very important for the control of wall turbulence. To ascertain the effect of near-wall modulation on the viscoelastic drag-reduced flow, the modified characteristics of a surfactant solution channel flow were investigated experimentally. The modulation was conducted on the boundary of the channel flow by injecting water from the whole surface of one side of the channel wall. The diffusion process of the injected water was observed by using the planar laser-induced fluorescence technique. The velocity statistics and characteristic structure including the spatial distributions of instantaneous streamwise velocity, swirling strength, and Reynolds shear stress were analyzed based on the velocity vectors acquired in the streamwise wall-normal plane by using the particle imaging velocimetry technique. The results indicated that the disturbance of the injected water was constricted within a finite range very near the dosing wall, and the Reynolds shear stress was increased in this region. However, the eventual drag reduction rate was found to be increased due to a relatively large decrement of viscoelastic shear stress in this near-wall region. Moreover, the flow structure under this modulation presented obvious regional characteristics. In the unstable disturbed region, the mixing of high-speed and low-speed fluids and the motions of ejection and sweep occurred actively. Many clockwise vortex cores were also found to be generated. This characteristic structure was similar to that in the ordinary turbulence of Newtonian fluid. Nevertheless, outside

  20. Precipitation characteristics for the Slovak republic and their link to the atmospheric circulation

    Science.gov (United States)

    Pokorná, Lucie; Pecho, Jozef; Faško, Pavol

    2013-04-01

    Slovak Republic is situated in the centre of Europe. Its terrain is rugged and altitude increases from the southern lowlands to mountains in the northeastern and northern parts of the region where it reaches more than 2000 m a. s. l. Precipitation in this region is affected by atmospheric systems coming from the Atlantic ocean (western direction) on one hand and from the Mediterranean on the other hand (southern direction). However cyclones passing the Baltic Sea play a significant role determining precipitation occurrence and amounts as well. All these factors together with local effects lead to three different precipitation regimes in Slovakia: (i) Continental (with low precipitation in winter and the highest in summer), (ii) Atlantic (with equally distributed precipi¬tation all year round) and (iii) Mediterranean (with highest pre¬cipitation in June or May and secon¬dary maximum in October-December). The Mediterranean regime is more pronounced in the southern part of Central Slovakia while the Continental in the northeastern Slovakia. In the contribution we focus on distribution of precipitation amounts during the year and on trends in occurrence of extreme precipitation and droughts. Series from 50 meteorological stations in the Slovak Republic from the period 1951, resp. 1961-2010, are used. The sub-regions with typical annual courses of precipitation are identified using cluster analysis. The temporal behaviour of mean precipitation totals during the second half of the 20th century is characterized by a significant decrease until the mid-1990s followed by an increase up to the present. The increase of precipitation totals is registered mainly in winter, and partly also in spring and autumn. Nevertheless the increase is not regular; short periods with heavy precipi-tation as well as longer and more severe drought spells have occurred more frequently in two recent decades. In the second part of this work, the influence of atmospheric circulation on

  1. [Pollution characteristics and health risk assessment of atmospheric volatile organic compounds (VOCs) in pesticide factory].

    Science.gov (United States)

    Tan, Bing; Wang, Tie-Yu; Pang, Bo; Zhu, Zhao-Yun; Wang, Dao-Han; Lü, Yong-Long

    2013-12-01

    A method for determining volatile organic compounds (VOCs) in air by summa canister collecting and gas chromatography/ mass spectroscopy detecting was adopted. Pollution condition and characteristics of VOCs were discussed in three representative pesticide factories in Zhangjiakou City, Hebei Province. Meanwhile, an internationally recognized four-step evaluation model of health risk assessment was applied to preliminarily assess the health risk caused by atmospheric VOCs in different exposure ways, inhalation and dermal exposure. Results showed that serious total VOCs pollution existed in all factories. Concentrations of n-hexane (6161.90-6910.00 microg x m(-3)), benzene (126.00-179.30 microg x m(-3)) and 1,3-butadiene (115.00-177.30 microg x m(-3)) exceeded the Chronic Inhalation Reference Concentrations recommended by USEPA, corresponding to 700, 30 and 2 microg x m(-3), respectively. Concentration of dichloromethane (724.00 microg x m(-3)) in factory B was also higher than the reference concentration (600 microg x m(-3)). Results of health risk assessment indicated that non-carcinogenic risk indexes of VOCs ranged from 1.00E-04 to 1.00E + 00 by inhalation exposure, and 1.00E-09 to 1.00E-05 by dermal exposure. Risk indexes of n-hexane and dichloromethane by inhalation exposure in all factories exceeded 1, and risk index of benzene by inhalation in factory B was also higher than 1. Carcinogenic risk indexes exposed to VOCs ranged from 1.00E-08 to 1.00E-03 by inhalation exposure and 1. oo00E -13 to 1.00E-08 by dermal exposure. Cancer risk of 1,3-butadiene by inhalation exceeded 1.0E-04, which lead to definite risk, and those of benzene by inhalation also exceeded the maximum allowable level recommended by International Commission on Radiological Protection (5.0E-05). The risks of dermal exposure presented the same trend as inhalation exposure, but the level was much lower than that of inhalation exposure. Thus, inhalation exposure of atmospheric VOCs was the

  2. Use of mutant-specific ion channel characteristics for risk stratification of long QT syndrome patients

    DEFF Research Database (Denmark)

    Jons, Christian; O-Uchi, Jin; Moss, Arthur J;

    2011-01-01

    predictor for cardiac events (syncope, aborted cardiac arrest, and sudden death) (hazard ratio = 2.10), whereas the length of the QT interval itself was not. Our results indicate that genotype and biophysical phenotype analysis may be useful for risk stratification of LQT1 patients and suggest that slow......Inherited long QT syndrome (LQTS) is caused by mutations in ion channels that delay cardiac repolarization, increasing the risk of sudden death from ventricular arrhythmias. Currently, the risk of sudden death in individuals with LQTS is estimated from clinical parameters such as age, gender, and...... the QT interval, measured from the electrocardiogram. Even though a number of different mutations can cause LQTS, mutation-specific information is rarely used clinically. LQTS type 1 (LQT1), one of the most common forms of LQTS, is caused by mutations in the slow potassium current (I(Ks)) channel a...

  3. Identification of Characteristic Protein Folding Channels in a Coarse-Grained Hydrophobic-Polar Peptide Model

    OpenAIRE

    Schnabel, Stefan; Bachmann, Michael; Janke, Wolfhard

    2007-01-01

    Folding channels and free-energy landscapes of hydrophobic-polar heteropolymers are discussed on the basis of a minimalistic off-lattice coarse-grained model. We investigate how rearrangements of hydrophobic and polar monomers in a heteropolymer sequence lead to completely different folding behaviors. Studying three exemplified sequences with the same content of hydrophobic and polar residues, we can reproduce within this simple model two-state folding, folding through intermediates, as well ...

  4. Single-phase flow characteristics in narrow channel under rolling motion

    International Nuclear Information System (INIS)

    Experimental studies of single-phase pressure drop in narrow rectangular channel under rolling motion were carried out. The rolling periods were 8, 12, 16 s, and the rolling angles were 10℃, 15℃, 30℃. Experimental results show that the frictional factors periodically fluctuate with time. The amplitude and average value of frictional factors decrease with the increasing of Reynolds numbers. At any moment, the transient frictional factors increase with the increasing of rolling angular acceleration. (authors)

  5. Ion Transport Characteristics of Individual Single-walled Carbon Nanotubes Mimic Those of Biological Ion Channels

    Science.gov (United States)

    Amiri, Hasti; Shepard, Kenneth; Nuckolls, Colin

    2014-03-01

    Transmembrane ionic channels play a crucial role in vital cellular activities by regulating the transport of ions and fluid across the cell membrane. Their structural complexity and flexibility as well as their many unique operational features, however, make their investigation extremely difficult. The simple, atomically smooth and well-defined structure of carbon nanotubes (CNTs) provides an excellent template for studying molecular transport at nanoscale. Additionally, CNTs have been suggested as analogues to biological pores since they share several common features such as nanometer size diameter, hydrophobic core and ultrafast water flow. Functionalizing the nanotube entrance can also mimic the selectivity filter of ion channels. In this work, we experimentally study ionic transport through individual single-walled CNTs connecting two fluid reservoirs as a function of pore properties and electrolyte type and concentration. We provide strong evidence that the electrostatic potentials arising from the ionized carboxyl groups at the pore entrance significantly influence the ion permeation in a manner consistent with a simple electrostatic mechanism. Lastly, the similarities of ionic transport mechanisms between individual single-walled CNTs and protein ion channels are discussed.

  6. Full equations utilities (FEQUTL) model for the approximation of hydraulic characteristics of open channels and control structures during unsteady flow

    Science.gov (United States)

    Franz, Delbert D.; Melching, Charles S.

    1997-01-01

    The Full EQuations UTiLities (FEQUTL) model is a computer program for computation of tables that list the hydraulic characteristics of open channels and control structures as a function of upstream and downstream depths; these tables facilitate the simulation of unsteady flow in a stream system with the Full Equations (FEQ) model. Simulation of unsteady flow requires many iterations for each time period computed. Thus, computation of hydraulic characteristics during the simulations is impractical, and preparation of function tables and application of table look-up procedures facilitates simulation of unsteady flow. Three general types of function tables are computed: one-dimensional tables that relate hydraulic characteristics to upstream flow depth, two-dimensional tables that relate flow through control structures to upstream and downstream flow depth, and three-dimensional tables that relate flow through gated structures to upstream and downstream flow depth and gate setting. For open-channel reaches, six types of one-dimensional function tables contain different combinations of the top width of flow, area, first moment of area with respect to the water surface, conveyance, flux coefficients, and correction coefficients for channel curvilinearity. For hydraulic control structures, one type of one-dimensional function table contains relations between flow and upstream depth, and two types of two-dimensional function tables contain relations among flow and upstream and downstream flow depths. For hydraulic control structures with gates, a three-dimensional function table lists the system of two-dimensional tables that contain the relations among flow and upstream and downstream flow depths that correspond to different gate openings. Hydraulic control structures for which function tables containing flow relations are prepared in FEQUTL include expansions, contractions, bridges, culverts, embankments, weirs, closed conduits (circular, rectangular, and pipe

  7. Nuclear fuel particles in the environment - characteristics, atmospheric transport and skin doses

    Energy Technology Data Exchange (ETDEWEB)

    Poellaenen, R

    2002-05-01

    In the present thesis, nuclear fuel particles are studied from the perspective of their characteristics, atmospheric transport and possible skin doses. These particles, often referred to as 'hot' particles, can be released into the environment, as has happened in past years, through human activities, incidents and accidents, such as the Chernobyl nuclear power plant accident in 1986. Nuclear fuel particles with a diameter of tens of micrometers, referred to here as large particles, may be hundreds of kilobecquerels in activity and even an individual particle may present a quantifiable health hazard. The detection of individual nuclear fuel particles in the environment, their isolation for subsequent analysis and their characterisation are complicated and require well-designed sampling and tailored analytical methods. In the present study, the need to develop particle analysis methods is highlighted. It is shown that complementary analytical techniques are necessary for proper characterisation of the particles. Methods routinely used for homogeneous samples may produce erroneous results if they are carelessly applied to radioactive particles. Large nuclear fuel particles are transported differently in the atmosphere compared with small particles or gaseous species. Thus, the trajectories of gaseous species are not necessarily appropriate for calculating the areas that may receive large particle fallout. A simplified model and a more advanced model based on the data on real weather conditions were applied in the case of the Chernobyl accident to calculate the transport of the particles of different sizes. The models were appropriate in characterising general transport properties but were not able to properly predict the transport of the particles with an aerodynamic diameter of tens of micrometers, detected at distances of hundreds of kilometres from the source, using only the current knowledge of the source term. Either the effective release height has

  8. Nuclear fuel particles in the environment - characteristics, atmospheric transport and skin doses

    International Nuclear Information System (INIS)

    In the present thesis, nuclear fuel particles are studied from the perspective of their characteristics, atmospheric transport and possible skin doses. These particles, often referred to as 'hot' particles, can be released into the environment, as has happened in past years, through human activities, incidents and accidents, such as the Chernobyl nuclear power plant accident in 1986. Nuclear fuel particles with a diameter of tens of micrometers, referred to here as large particles, may be hundreds of kilobecquerels in activity and even an individual particle may present a quantifiable health hazard. The detection of individual nuclear fuel particles in the environment, their isolation for subsequent analysis and their characterisation are complicated and require well-designed sampling and tailored analytical methods. In the present study, the need to develop particle analysis methods is highlighted. It is shown that complementary analytical techniques are necessary for proper characterisation of the particles. Methods routinely used for homogeneous samples may produce erroneous results if they are carelessly applied to radioactive particles. Large nuclear fuel particles are transported differently in the atmosphere compared with small particles or gaseous species. Thus, the trajectories of gaseous species are not necessarily appropriate for calculating the areas that may receive large particle fallout. A simplified model and a more advanced model based on the data on real weather conditions were applied in the case of the Chernobyl accident to calculate the transport of the particles of different sizes. The models were appropriate in characterising general transport properties but were not able to properly predict the transport of the particles with an aerodynamic diameter of tens of micrometers, detected at distances of hundreds of kilometres from the source, using only the current knowledge of the source term. Either the effective release height has been higher

  9. Single-phase convection heat transfer characteristics of pebble-bed channels with internal heat generation

    International Nuclear Information System (INIS)

    Graphical abstract: The core of the water-cooled pebble bed reactor is the porous channels which stacked with spherical fuel elements. The gaps between the adjacent fuel elements are complex because they are stochastic and often shift. We adopt electromagnetic induction heating method to overall heat the pebble bed. By comparing and analyzing the experimental data, we get the rule of power distribution and the rule of heat transfer coefficient with particle diameter, heat flux density, inlet temperature and working fluid's Re number. Highlights: ► We adopt electromagnetic induction heating method to overall heat the pebble bed to be the internal heat source. ► The ball diameter is smaller, the effect of the heat transfer is better. ► With Re number increasing, heat transfer coefficient is also increasing and eventually tends to stabilize. ► The changing of heat power makes little effect on the heat transfer coefficient of pebble bed channels. - Abstract: The reactor core of a water-cooled pebble bed reactor includes porous channels that are formed by spherical fuel elements. This structure has notably improved heat transfer. Due to the variability and randomness of the interstices in pebble bed channels, heat transfer is complex, and there are few studies regarding this topic. To study the heat transfer characters of pebble bed channels with internal heat sources, oxidized stainless steel spheres with diameters of 3 and 8 mm and carbon steel spheres with 8 mm diameters are used in a stacked pebble bed. Distilled water is used as a refrigerant for the experiments, and the electromagnetic induction heating method is used to heat the pebble bed. By comparing and analyzing the experimental results, we obtain the governing rules for the power distribution and the heat transfer coefficient with respect to particle diameter, heat flux density, inlet temperature and working fluid Re number. From fitting of the experimental data, we obtain the dimensionless average

  10. The characteristics of local atmospheric circulation around the Wolsung NPP in Korea

    International Nuclear Information System (INIS)

    The transport of air pollutants in coastal regions has been known to be strongly affected by the mesoscale atmospheric circulations such as sea-land breezes. These mesoscale atmospheric circulations depend on synoptic weather conditions. In this study, a three-dimensional sea-land breeze model was developed to evaluate the effects of the sea and land breezes on the atmospheric dispersion of radioactive materials released from nuclear power plants in Korea. In the model, the hydrostatic primitive equations in the terrain-following coordinate system were used. The mesoscale atmospheric circulation simulation were carried out under various synoptic weather conditions for all seasons around the Wolsung nuclear power plant site

  11. Characteristics of atmospheric aerosol optical depth variation in China during 1993-2012

    Science.gov (United States)

    Xu, Xiaofeng; Qiu, Jinhuan; Xia, Xiangao; Sun, Ling; Min, Min

    2015-10-01

    The long-term variations of atmospheric aerosol optical depth (AOD) over 14 first-class solar radiation stations in China during 1993-2012 are studied. The AOD at 750 nm wavelength is retrieved with the hourly accumulated direct solar radiation by using a broadband extinction method. The retrievals are validated in comparison with AERONET (Aerosol Robotic Network) and MODIS (Moderate Resolution Imaging Spectroradiometer) AOD products. For the comparison with AERONET, the correlation coefficient (R), mean bias error (MBE) and root mean square error (RMSE) of the monthly mean AODs are respectively 0.848, 0.029 and 0.101. Based on the statistical analysis, the monthly, seasonal and annual AOD variation characteristics are categorized as follow: (1) There are three major types of the seasonal AOD variations, which shows the largest seasonal averaged AOD appearing in spring, summer and winter. The smallest seasonal averaged AOD appears mostly in autumn. (2) Beijing and Guangzhou show a significant decreasing trend of the yearly AOD, while an increasing tendency appears in Zhengzhou, Shanghai, Kunming, Kashi and Wuhan. Although no significant variation trends are found, some fluctuations appear in the 20-year period in other cities. (3) The 20-year mean AOD ranges from 0.135 (Lhasa) to 0.678 (Zhengzhou). The aerosol hygroscopic growth contributes a lot to AOD in major cities in the eastern part of China, while not in most cities in the western part. A simple correction method is applied for enhancing the relationship of AOD and PM2.5 concentration.

  12. Characteristic of coal combustion in oxygen/carbon dioxide atmosphere and nitric oxide release during this process

    International Nuclear Information System (INIS)

    Combustion characteristic of a bituminous coal and an anthracite coal in oxygen/carbon dioxide (O2/CO2) atmosphere is investigated in a thermogravimetric (TG) analyzer. The characteristic parameters, which are deduced from the TG-DTG (differential thermogravimetric) curves, show that the coal combustion process is basically kept consistent in O2/CO2 and O2/N2 atmosphere at the O2 concentration of 20%. The Coats-Redfern method with the reaction order of 1.25 could perfectly describe the combustion process in these two different atmospheres through the calculation of the kinetic parameters for the two coals. Nitric oxide (NO) release is concentrated in a narrower time period in O2/CO2 atmosphere compared with the one in O2/N2 atmosphere during the coal combustion process. Though the high value of the NO release rate peak, the total conversion of the fuel-N to NO is strongly depressed in O2/CO2 atmosphere, and at 1473 K, the conversion is reduced by 28.99% for the bituminous coal and 22.54% for the anthracite coal, respectively. When O2 concentration is increased from 20% to 40% in O2/CO2 atmosphere, the coal combustion property is obviously improved with the shift of the whole process into the lower temperature zone and the more intensive of the reaction occurrence in a narrower temperature range. However, the total fuel-N to NO conversion is increased accordingly. For bituminous coal the increase is 17.22% at 1073 K and 20.51% at 1173 K, and for anthracite coal the increase is 15.73% at 1073 K and 16.19% at 1173 K.

  13. Effectiveness Using Circular Fibre Steel Flap Gate As a Control Structure Towards the Hydraulic Characteristics in Open Channel

    Science.gov (United States)

    Adib, M. R. M.; Amirza, A. R. M.; Wardah, T.; Junaidah, A.

    2016-07-01

    Hydraulic control gate structure plays an important role in regulating the flow of water in river, canal or water reservoir. One of the most appropriate structures in term of resolving the problem of flood occured is the construction of circular fibre steel flap gate. Therefore, an experiment has been conducted by using an open channel model at laboratory. In this case, hydraulic jump and backwater were the method to determined the hydraulic characteristics of circular fibre steel flap gate in an open channel model. From the experiment, the opening angle of flap gate can receive discharges with the highest flow rate of 0.035 m3/s with opening angle was 47°. The type of jump that occurs at the slope of 1/200 for a distance of 5.0 m is a standing jump or undulating wave. The height of the backwater can be identified based on the differences of specific force which is specific force before jump, F1 and specific force after jump, F2 from the formation of backwater. Based on the research conducted, the tendency of incident backwater wave occurred was high in every distance of water control location from water inlet is flap slope and the slope of 1/300 which is 0.84 m/s and 0.75 m/s of celerity in open channel model.

  14. Channel Characteristics and Performance of MIMO E-SDM Systems in an Indoor Time-Varying Fading Environment

    Directory of Open Access Journals (Sweden)

    Nishimoto Hiroshi

    2010-01-01

    Full Text Available Multiple-input multiple-output (MIMO systems employ advanced signal processing techniques. However, the performance is affected by propagation environments and antenna characteristics. The main contributions of the paper are to investigate Doppler spectrum based on measured data in a typical meeting room and to evaluate the performance of MIMO systems based on an eigenbeam-space division multiplexing (E-SDM technique in an indoor time-varying fading environment, which has various distributions of scatterers, line-of-sight wave existence, and mutual coupling effect among antennas. We confirm that due to the mutual coupling among antennas, patterns of antenna elements are changed and different from an omnidirectional one of a single antenna. Results based on the measured channel data in our measurement campaigns show that received power, channel autocorrelation, and Doppler spectrum are dependent not only on the direction of terminal motion but also on the antenna configuration. Even in the obstructed-line-of-sight environment, observed Doppler spectrum is quite different from the theoretical U-shaped Jakes one. In addition, it has been also shown that a channel change during the time interval between the transmit weight matrix determination and the actual data transmission can degrade the performance of MIMO E-SDM systems.

  15. An experimental investigation of the characteristics of free-surface turbulence in channel flow

    International Nuclear Information System (INIS)

    The structural features of turbulence at the free surface of a channel flow have been experimentally investigated. The experiments were conducted in a horizontal channel of large aspect ratio in the (depth based) Reynolds number range of 2800 endash 8800. The results indicate that the persistent structures on the free surface can be classified as upwellings, downdrafts, and spiral eddies. Upwellings are shown to be related to the bursts originating in the sheared region at the channel bottom and the eddies are seen to be generated at the edges of the upwellings. The eddies often merge if rotating in the same direction, and form open-quotes pairsclose quotes if rotating in opposite directions emdash though there are occasional mergers of such counter-rotating ones. The spiral eddies decay slowly and are sometimes annihilated by fresh upwellings. The population densities and the persistence times of the various structures were measured for different flow conditions. The resulting data show that the physical parameters characterizing the structures at the interface, scale with a mix of inner (wall shear stress and viscosity) and outer variables. Measurement of the streamwise and spanwise velocities at the free-surface were made by particle imaging velocimetry (PIV) and the surface normal velocity near the free-surface estimated by continuity. The results indicate that the upwellings and spiral eddy regions would be expected to dominate scalar transport rates at high Prandtl/Schmidt numbers. The one-dimensional energy spectra of the flow field at the free-surface compare well with direct numerical simulations and show a region with -5/3 slope at low wave numbers. This experimentally confirms a previous result regarding the two-dimensionality of turbulence near the free surface, based on numerical simulations by Pan and Banerjee [Phys. Fluids 7, 1649 (1995)]. copyright 1998 American Institute of Physics

  16. On the Performance of Free-Space Optical Systems over Generalized Atmospheric Turbulence Channels with Pointing Errors

    KAUST Repository

    Ansari, Imran Shafique

    2015-03-01

    Generalized fading has been an imminent part and parcel of wireless communications. It not only characterizes the wireless channel appropriately but also allows its utilization for further performance analysis of various types of wireless communication systems. Under the umbrella of generalized fading channels, a unified performance analysis of a free-space optical (FSO) link over the Malaga (M) atmospheric turbulence channel that accounts for pointing errors and both types of detection techniques (i.e. indirect modulation/direct detection (IM/DD) as well as heterodyne detection) is presented. Specifically, unified exact closed-form expressions for the probability density function (PDF), the cumulative distribution function (CDF), the moment generating function (MGF), and the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO transmission system are presented, all in terms of the Meijer\\'s G function except for the moments that is in terms of simple elementary functions. Then capitalizing on these unified results, unified exact closed-form expressions for various performance metrics of FSO link transmission systems are offered, such as, the outage probability (OP), the higher-order amount of fading (AF), the average error rate for binary and M-ary modulation schemes, and the ergodic capacity (except for IM/DD technique, where closed-form lower bound results are presented), all in terms of Meijer\\'s G functions except for the higher-order AF that is in terms of simple elementary functions. Additionally, the asymptotic results are derived for all the expressions derived earlier in terms of the Meijer\\'s G function in the high SNR regime in terms of simple elementary functions via an asymptotic expansion of the Meijer\\'s G function. Furthermore, new asymptotic expressions for the ergodic capacity in the low as well as high SNR regimes are derived in terms of simple elementary functions via utilizing moments. All the presented results are

  17. Noise Characteristics of Readout Electronics for 64-Channel DROS Magnetocardiography System

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. M.; Kim, K. D.; Lee, Y. H.; Yu, K. K.; Kim, K. W.; Kwon, H. C. [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Sasada, Ichiro [Dept. of Applied Science for Electrics and Materials, Kyushu University, Fukuoka (Japan)

    2005-10-15

    We have developed control electronics to operate flux-locked loop (FLL), and analog signal filters to process FLL outputs for 64-channel Double Relaxation Oscillation SQUID (DROS) magnetocardiography (MCG) system. Control electronics consisting of a preamplifier, an integrator, and a feedback, is compact and low-cost due to larger swing voltage and flux-to-voltage transfer coefficients of DROS than those of dc SQUIDs. Analog signal filter (ASF) serially chained with a high-pass filter having a cut-off frequency of 0.1 Hz, an amplifier having a gain of 100, a low-pass filter of 100 Hz, and a notch filter of 60 Hz makes FLL output suitable for MCG. The noise of a preamplifier in FLL control electronics is 7 nV/Hz 1.5 nV/Hz at 100 Hz that contributes 6 fT/Hz at 1 Hz, 1.3 fT/Hz at 100 Hz in readout electronics, and the noise of ASF electronics is 150 {mu}V/Hz equivalent to 0.13 fT/Hz within the range of 1 - 100 Hz. When DROSs are connected to readout electronics inside a magnetically shielded room, the noise of 64-channel DROS system is 10 fT/Hz at 1 Hz, 5fT/Hz at 100 Hz on the average, low enough to measure human MCG.

  18. Effect of equal channel angular extrusion on Al-6063 bending fatigue characteristics

    Science.gov (United States)

    Nemati, J.; Majzoobi, G. H.; Sulaiman, S.; Baharudin, B. T. H. T.; Azmah Hanim, M. A.

    2015-04-01

    The purpose of this investigation was to refine the grains of annealed 6063 aluminum alloy and to improve its yield stress and ultimate strength. This was accomplished via the equal channel angular extrusion (ECAE) process at a temperature of 200°C using route A, with a constant ram speed of 30 mm/min through a die angle of 90° between the die channels for as many as 6 passes. The experiments were conducted on an Avery universal testing machine. The results showed that the grain diameter decreased from 45 μm to 2.8 μm after 6 extrusion passes. The results also indicated that the major improvement in fatigue resistance occurred after the first pass. The subsequent passes improved the fatigue life but at a considerably lower rate. A maximum increase of 1100% in the case of low applied stresses and an approximately 2200% increase in fatigue resistance in the case of high applied stresses were observed after 5 passes. The improvement of fatigue resistance is presumed to be due to (1) a reduction in the size and the number of Si crystals with increasing number of ECAE passes, (2) the aggregation of Cu during the ECAE process, (3) the formation and growth of CuAl2 grains, and (4) grain refinement of the Al-6063 alloy during the ECAE process.

  19. A study of the thermal and optical characteristics of radiometric channels for Earth radiation budget applications

    Science.gov (United States)

    Mahan, J. R.; Tira, Nour E.

    1991-01-01

    An improved dynamic electrothermal model for the Earth Radiation Budget Experiment (ERBE) total, nonscanning channels is formulated. This model is then used to accurately simulate two types of dynamic solar observation: the solar calibration and the so-called pitchover maneuver. Using a second model, the nonscanner active cavity radiometer (ACR) thermal noise is studied. This study reveals that radiative emission and scattering by the surrounding parts of the nonscanner cavity are acceptably small. The dynamic electrothermal model is also used to compute ACR instrument transfer function. Accurate in-flight measurement of this transfer function is shown to depend on the energy distribution over the frequency spectrum of the radiation input function. A new array-type field of view limiter, whose geometry controls the input function, is proposed for in-flight calibration of an ACR and other types of radiometers. The point spread function (PSF) of the ERBE and the Clouds and Earth's Radiant Energy System (CERES) scanning radiometers is computed. The PSF is useful in characterizing the channel optics. It also has potential for recovering the distribution of the radiative flux from Earth by deconvolution.

  20. Delay, Doppler, and amplitude characteristics of HF signals received over a 1300-km transauroral sky wave channel

    Science.gov (United States)

    Wagner, L. S.; Goldstein, J. A.; Rupar, M. A.; Kennedy, E. J.

    1995-05-01

    Channel probe observations of propagation conditions along a 1294-km transauroral path between Sondrestrom, Greenland, and Keflavik, Iceland, were made during the period from March 13 to April 2, 1992. The midpoint of this path was located at a corrected geomagnetic latitude of 72°. The objective of these measurements was to supplement the existing data base describing propagation conditions on the HF transauroral channel with data pertaining to a period around the time of solar maximum. Received signals for this path fell into three distinct groups depending on their amplitude and delay and Doppler spread characteristics. These are (1) strong, specularly reflected ionospheric returns characteristic of a quiescent daytime ionospheric channel during magnetically quiet conditions; (2) strong specular multipath signals reflected from horizontal gradients of electron density and regularly encountered at night; and (3) weak scatter returns that are also a persistent nighttime phenomenon. The scatter returns are usually observed at delays exceeding those anticipated for the one-hop return and, very often, at frequencies that are well above the MUF for the great circle propagation path. The multipath and scatter returns exhibit large delay and Doppler spreads indicative of spatially extensive distributions of drifting and randomly moving irregularities. Two measurement events are discussed which illustrate these conclusions: a noontime measurement with Kp = 3, and a midnight measurement with Kp = 2. The noontime measurement exhibited a scatter return from an isolated irregularity region in addition to the usual ionospheric reflected signals. A simple irregularity drift model produced delay and Doppler shift curves that were consistent with those observed for the scatter component of the received signal and supported a hypothesis of an irregularity region drift speed of 1200 m s-1 parallel to the great circle propagation path.

  1. 大气信道简化单次散射模型%Atmospheric channel simplification single scatter model

    Institute of Scientific and Technical Information of China (English)

    汤义男; 赵卫; 谢小平

    2013-01-01

    Most existing study on non-line-of-sight solar-blind ultraviolet communication single scatter models use the prolate-spheroidal coordinates to obtain solutions. In the solving process, the effective scattering volume must undergo the difficult numerical integration and the three groups of integral limits which determine the volume can be calculated. The widely adopted yet complex single-scatter channel model is significantly simplified by means of a closed-form expression for tractable analysis in this paper. And the path loss is given as a function of transceiver geometries as well as scattering and absorption coefficient. The simulation results of transmission distance and path loss show that the approximated path loss matches that from direct numerical integration very well. Using the closed-form expression of path loss, the influence of atmospheric visibility on the path loss and bit-error-rate of the ultraviolet communication system is simulated. The simulation results show that: the better weather and the higher visibility do not result in greater system performances, but when the visibility equals 9-10 km, the best performance can be obtained.%采用椭球坐标系研究非直视日盲紫外光通信的单次散射模型,求解过程中要对有效散射体的体积进行复杂的数值积分并确定三组积分限.为便于分析,使用近似表达式极大简化了复杂单次散射信道模型,得出路径损耗是收发机几何结构与大气散射吸收系数的函数.对传输距离和路径损耗的仿真证明,该近似表达式与原始模型的所得结果吻合很好.利用该近似表达式,分别仿真分析了大气能见度对紫外光通信系统路径损耗和误码率的影响,仿真结果表明,大气能见度并不是越高越好,而是在能见度为10 km时紫外光通信系统有最佳性能.

  2. Mechanical properties and fracture characteristics of high carbon steel after equal channel angular pressing

    International Nuclear Information System (INIS)

    The ultra-microduplex structure was fabricated in a fully pearlitic Fe–0.8 wt% C steel after equal channel angular pressing (ECAP) at 923 K via the Bc route. The microstructures and mechanical properties, before and after deformation, were investigated using scanning electron microscopy and mini-tensile tests. The cementite lamellae are gradually spheroidized by increasing the number of ECAP passes. After four passes, the cementite lamellae are fully spheroidized. Microhardness and the ultimate tensile strength of pearlite increase with the strain, up to a peak value (after two passes) and then decrease significantly. The yield strength, elongation and percentage of reduction in area increase with the number of ECAP passes. The tensile fracture morphology changes gradually from brittle cleavage to typical ductile fracture after four passes

  3. Two-phase Flow Characteristics in a Gas-Flow Channel of Polymer Electrolyte Membrane Fuel Cells

    Science.gov (United States)

    Cho, Sung Chan

    Fuel cells, converting chemical energy of fuels directly into electricity, have become an integral part of alternative energy and energy efficiency. They provide a power source of high energy-conversion efficiency and zero emission, meeting the critical demands of a rapidly growing society. The proton exchange membrane (PEM) fuel cells, also called polymer electrolyte fuel cells (PEFCs), are the major type of fuel cells for transportation, portable and small-scale stationary applications. They provide high-power capability, work quietly at low temperatures, produce only water byproduct and no emission, and can be compactly assembled, making them one of the leading candidates for the next generation of power sources. Water management is one of the key issues in PEM fuel cells: appropriate humidification is critical for the ionic conductivity of membrane while excessive water causes flooding and consequently reduces cell performance. For efficient liquid water removal from gas flow channels of PEM fuel cells, in-depth understanding on droplet dynamics and two-phase flow characteristics is required. In this dissertation, theoretical analysis, numerical simulation, and experimental testing with visualization are carried out to understand the two-phase flow characteristics in PEM fuel cell channels. Two aspects of two-phase phenomena will be targeted: one is the droplet dynamics at the GDL surface; the other is the two-phase flow phenomena in gas flow channels. In the former, forces over a droplet, droplet deformation, and detachment are studied. Analytical solutions of droplet deformation and droplet detachment velocity are obtained. Both experiments and numerical simulation are conducted to validate analytical results. The effects of contact angle, channel geometry, superficial air velocity, properties of gas phase fluids are examined and criteria for the detachment velocity are derived to relate the Reynolds number to the Weber number. In the latter, two-phase flow

  4. Tidal bedform characteristics in the Jade and Weser tidal inlet channels, German North Sea coast

    Science.gov (United States)

    Feng, H. S.; Winter, C.; Svenson, C.; Maushake, C.

    2009-12-01

    Compound bedforms are ubiquitous in marine environments with sandy beds and sufficient hydrodynamic forcing. In tidal channels, these features can build up to several meters in height and hundreds of meters in length. Recent high-resolution bathymetric mapping has revealed the complex morphology and morphodynamics of superimposed bedforms of different sizes and geometries. In this study, high-resolution multibeam echo sounder bathymetry and parametric sediment echo sounder (SES) sub-bottom data were compiled and visualized in Fledermaus 7 to identify typical bedform geometries and internal structures along 40 km of the Jade tidal channel and 50 km of the tide-dominated Weser estuary at the German North Sea coast. These extensive bathymetric datasets show the confined occurrence and the diversity of shapes and dimensions of the bedforms, ranging from simple geometries to compound superpositions of large subsidiary dunes, from small bedforms with lengths of the order of 20 m and heights of 1 m to large features 200 m in length and 10 m in height, and from symmetrical shapes to ebb- or flood-dominated geometries. The parametric echo sounder imaged sub-bottom profiles up to 4 m deep, showing relatively simple foreset bedding in simple dunes and complex internal structures in compound bedforms. Cross-bedding signatures indicating an ebb orientation were recognized within symmetric and flood-directed bedforms, suggesting a temporal re-orientation of the whole structure. Locally small buried bedforms, overgrown by recent larger bedforms, were detected. These indicate changes in the local hydrodynamic conditions or variations in the sediment supply.

  5. Fuel Temperature Characteristics for Fuel Channels using Burnable Poison in the CANDU reactor

    International Nuclear Information System (INIS)

    Although the CANFLEX RU fuel bundle loaded 11.0 wt% Er2O3 are originally designed focused on the safety characteristics, the fuel temperature characteristics is revealed to be not deteriorated but rather is slightly enhanced by the decreased fuel temperature in the outer ring compared with that of standard 37 fuel bundle. Recently, for an equilibrium CANDU core, the power coefficient was reported to be slightly positive when newly developed Industry Standard Tool set reactor physics codes were used. Therefore, it is required to find a new way to effectively decrease the positive power coefficient of CANDU reactor without seriously compromising the economy. In order to make the power coefficient of the CANDU reactor negative at the operating power, Roh et al. have evaluated the various burnable poison (BP) materials and its loading scheme in terms of the fuel performance and reactor safety characteristics. It was shown that reactor safety characteristics can be greatly improved by the use of the BP in the CANDU reactor. In a view of safety, the fuel temperature coefficient (FTC) is an important safety parameter and it is dependent on the fuel temperature. For an accurate evaluation of the safety-related physics parameters including FTC, the fuel temperature distribution and its correlation with the coolant temperature should be accurately identified. Therefore, we have evaluated the fuel temperature distribution of a CANFLEX fuel bundle loaded with a burnable poison and compared the standard 37 element fuel bundle and CANFELX-NU fuel bundle

  6. Characteristics of the detection system of the Orsay Synchrocyclotron achromatic channel: study and determination

    International Nuclear Information System (INIS)

    Once the multiwire proportional chamber working principle studied it is shown that the avalanche must not necessary surround the anode wire. Geometrical characteristics of the MWPC used behind the 'Montpellier' spectrometer of the IPN synchrocyclotron, are determined from an evaluation of the induced charges on the cathode and anode wires

  7. Characteristics and distributions of atmospheric mercury emitted from anthropogenic sources in Guiyang, southwestern China

    Science.gov (United States)

    Continuous measurements of speciated atmospheric mercury (Hg), including gaseous elemental mercury (GEM), particulate mercury (PHg), and reactive gaseous mercury (RGM) were conducted in Guizhou Province, southwestern China. Guiyang Power Plant (GPP), Guiyang Wujiang Cement Plant,...

  8. Heat transfer and flow region characteristics study in a non-annular channel between rotor and stator

    Directory of Open Access Journals (Sweden)

    Nili-Ahmadabadi M.

    2012-01-01

    Full Text Available This paper will present the results of the experimental investigation of heat transfer in a non-annular channel between rotor and stator similar to a real generator. Numerous experiments and numerical studies have examined flow and heat transfer characteristics of a fluid in an annulus with a rotating inner cylinder. In the current study, turbulent flow region and heat transfer characteristics have been studied in the air gap between the rotor and stator of a generator. The test rig has been built in a way which shows a very good agreement with the geometry of a real generator. The boundary condition supplies a non-homogenous heat flux through the passing air channel. The experimental devices and data acquisition method are carefully described in the paper. Surface-mounted thermocouples are located on the both stator and rotor surfaces and one slip ring transfers the collected temperature from rotor to the instrument display. The rotational speed of rotor is fixed at three under: 300rpm, 900 rpm and 1500 rpm. Based on these speeds and hydraulic diameter of the air gap, the Reynolds number has been considered in the range: 4000characteristics.

  9. Estimating bacteria emissions from inversion of atmospheric transport: sensitivity to modelled particle characteristics

    OpenAIRE

    S. M. Burrows; Rayner, P. J.; Butler, T; M. G. Lawrence

    2013-01-01

    Model-simulated transport of atmospheric trace components can be combined with observed concentrations to obtain estimates of ground-based sources using various inversion techniques. These approaches have been applied in the past primarily to obtain source estimates for long-lived trace gases such as CO2. We consider the application of similar techniques to source estimation for atmospheric aerosols, using as a case study the estimation of bacteria emissio...

  10. Characteristics of aerosol at a lower atmospheric layer in DRAGON field campaign

    Science.gov (United States)

    KUJI, M.; Azuma, Y.; Kitakoga, S.; Sano, I.; Holben, B. N.

    2013-12-01

    Air pollution arises severely over East Asia with the rapid economic development nowadays. Monitoring the atmospheric environment, as one of the purposes, an intensive field campaign, Distributed Regional Aerosol Gridded Observation Networks (DRAGON), was carried out in the spring of year 2012, led by National Aeronautics and Space Administration (NASA). At that time, atmospheric phenomena such as Yellow sand and haze events were observed at Nara in the western part of Japan, as one of the DRAGON observation sites. The atmospheric events were characterized with the AErosol RObotic NETwork (AERONET) data. As a result of the data analysis, it was found that more light-absorbing and smaller particles dominated at the lower than upper atmospheric layer for the Kosa event in particular. A backward trajectory analysis suggested that the Yellow sand event traveled over the East Asian industrial cities, which could lead to a mixture of sand and air pollutants with moderate particle size and light-absorptivity. In addition, visibility observation was evaluated quantitatively with AERONET data in the DRAGON campaign since eye observation was inherently semi-quantitative. The extinction coefficient estimated from visibility was compared to that from AERONET. As a result, it was found that the extinction coefficients were generally consistent to each other. But there were some discrepancies, which could be caused with the atmospheric phenomena or aerosol types. It is confirmed that visibility is strongly influenced with aerosols in the case of severe atmospheric phenomena in particular.

  11. Effect of Aspect Ratio, Channel Orientation, Rib Pitch-to-Height Ratio, and Number of Ribbed Walls on Pressure Drop Characteristics in a Rotating Channel with Detached Ribs

    Directory of Open Access Journals (Sweden)

    K. Arun

    2007-01-01

    Full Text Available The present work involves experimental investigation of the effects of aspect ratio, channel orientation angle, rib pitch-to-height ratio (P/e, and number of ribbed walls on friction factor in orthogonally rotating channel with detached ribs. The ribs are separated from the base wall to provide a small region of flow between the base wall and the ribs. Experiments have been conducted at Reynolds number ranging from 10000–17000 with rotation numbers varying from 0–0.38. Pitch-to-rib height ratios (P/e of 5 and 10 at constant rib height-to-hydraulic diameter ratio (e/D of 0.1 and a clearance ratio (C/e of 0.38 are considered. The rib angle of attack with respect to mainstream flow is 90∘. The channel orientation at which the ribbed wall becomes trailing surface (pressure side on which the Coriolis force acts is considered as the 0∘ orientation angle. For one-wall ribbed case, channel is oriented from 0∘ to 180∘ about its axis in steps of 30∘ to change the orientation angle. For two-wall ribbed case, the orientation angle is changed from 0∘ to 90∘ in steps of 30∘. Friction factors for the detached ribbed channels are compared with the corresponding attached ribbed channel. It is found that in one-wall detached ribbed channel, increase in the friction factor ratio with the orientation angle is lower for rectangular channel compared to that of square channel for both the pitch-to-rib height ratios of 5 and 10 at a given Reynolds number and rotation number. Friction factor ratios of two-wall detached ribbed rectangular channel are comparable with corresponding two-wall detached ribbed square channel both under stationary and rotating conditions.

  12. Application of a heterodyne laser system to determine parameters of turbulent atmosphere

    International Nuclear Information System (INIS)

    The use of a heterodyne laser system in atmospheric measurements has been proposed. The continuous registration of optical phase variations of radiation propagating in the atmospheric channel has been carried out. From recorded data, the integral characteristics of a turbulence state in the radiation propagation channel are obtained.

  13. Atmospheric and Coupled Model Intercomparison in Terms of Amplitude-Phase Characteristics of Surface Air Temperature Annual Cycle

    Institute of Scientific and Technical Information of China (English)

    Alexey V. ELISEEV; Igor I. MOKHOV; Konstantin G. RUBINSTEIN; Maria S. GUSEVA

    2004-01-01

    A model intercomparison in terms of surface air temperature annual cycle ampitude-phase characteristics(SAT AC APC)is performed. The models included in the intercomparison belong to two groups:five atmospheric models with prescribed sea surface temperature and sea ice cover and four coupled models forced by the atmospheric abundances of anthropogenic consituents (in total six coupled model simulations). Over land, the models, simulating higher than observed time averaged SAT,also tend to simulate smaller than observed amplitude of its annual and semiannual harmonics and (outside the Tropics laterthan-observed spring and autumn moments. The models with larger(smaller) time averaged amplitudes of annual and semiannual harmonics also tend to simulate larger(smaller)interannual standard deviations. Over the oceans, the coupled models with larger interannual standard deviations of annual mean SAT tend to simulate larger interannual standard deviations of both annual and semiannual SAT harmonics amplitudes. Most model errors are located in the belts 60°-70°N and 60°-70°S and over Antarctica. These errors are larger for those coupled models which do not employ dynamical modules for sea ice.No systematic differences are found in the simulated time averaged fields of the surface air temperature annual cycle characteristics for atmospheric models on one hand and for the coupled models on the other. But the coupled models generally simulate interannual variability of SAT AC APC better than the atmospheric models (which tend to underestimate it). For the coupled models, the results are not very sensitive to the choice of the particular scenario of anthropogenic forcing.There is a strong linear positive relationship between the model simulated time averaged semiannual SAT harmonics amplitude and interannual standard deviation of annual mean SAT.It is stronger over the tropical oceans and is weaker in the extratropics. In the tropical oceanic areas, it is stronger for the

  14. Numerical research on fluid mixing characteristics in a non-heated parallel channel by supercritical freon

    International Nuclear Information System (INIS)

    In the thermal-hydraulic design of supercritical water-cooled reactors, it is required to establish a thermal-hydraulic analysis method which can simulate the heat transfer and fluid flow characteristics of supercritical fluids precisely. A crossing flow is a phenomenon in which the fluid flowing through the inside of a fuel bundle in the perpendicular direction moves between subchannels to a transverse direction. The crossing flow influences the removal heat of a reactor core greatly. In the present study, results of the preliminary crossing flow simulation are described. (author)

  15. Study of the flow characteristics of coolant channel of fuel blocks for HTGR

    International Nuclear Information System (INIS)

    In a loss of forced cooling accident, decay heat in HTGRs must be removed by radiation, thermal conduction and natural convection. Passive heat removal performance is of primary concern for enhancing inherent safety features of HTGRs. Therefore, the thermal hydraulic analyses for normal operation and a loss of forced cooling accident are conducted by using thermal hydraulic CFD code. And further, a multi-hole type fuel block of MHTGR is also modeled and the flow and heat transfer characteristics are compared with a pin-in-block type fuel block. (author)

  16. Effect of annealing atmosphere on phase formation and electrical characteristics of bismuth ferrite thin films

    International Nuclear Information System (INIS)

    Bismuth ferrite thin films were deposited on Pt/Ti/SiO2/Si substrates by a soft chemical method and spin-coating technique. The effect of annealing atmosphere (air, N2 and O2) on the structure and electrical properties of the films are reported. X-ray diffraction analysis reveals that the film annealed in air atmosphere is a single-phase perovskite structure. The films annealed in air showed better crystallinity and the presence of a single BFO phase leading to lower leakage current density and superior ferroelectric hysteresis loops at room temperature. In this way, we reveal that BFO film crystallized in air atmosphere by the soft chemical method can be useful for practical applications, including nonvolatile digital memories, spintronics and data-storage media.

  17. Monitoring of the terrestrial atmospheric characteristics with using of stellar and solar photometry

    CERN Document Server

    Alekseeva, G A; Leiterer, U; Naebert, T; Novikov, V V; Pakhomov, V P

    2010-01-01

    On the basis of experience acquired at creation of the Pulkovo Spectrophotometric Catalog the method of investigation of a terrestrial atmospheric components (aerosols and water vapor) in night time are designed. For these purposes the small-sized photometers were created. Carried out in 1995-1999{\\Gamma}.{\\Gamma}. series of night and daily monitoring of the atmospheric condition in Pulkovo, in MGO by A.I.Voejkov., in Germany (complex experiments LITFASS 98 and LACE 98) confirmed suitability of devices, techniques of observations and their reduction designed in Pulkovo Observatory for the solution of geophysical and ecological problems. A final aim of this work - creation of small-sized automatic complexes (telescope + photometer), which would be rightful component of meteorological observatories. Such complexes will work without the help of the observer and would provide the daily monitoring of a terrestrial atmosphere.

  18. Characteristics of the aerosol particulates in the atmosphere in an urban environment at Faisalabad, Pakistan

    International Nuclear Information System (INIS)

    The deposition of trace and major elements from the atmosphere to the ground is an important factor for plants, animals and humans as well. Total suspended particulate matter was measured by a standard gravimetric technique. A scanning electron microscope was used for the evaluation of the size distribution and morphological structures of the aerosol particulates trapped on the surface of filter paper. The aerosol particulates were studied by a scanning electron microscope at various magnification. The trace elemental composition in the atmosphere of Faisalabad was studied by using instrumental neutron activation analysis (INAA) and atomic absorption spectrometry (AAS). Concentrations of 23 trace elements and a major one were determined in samples of aerosol particulates collected during a longe sampling period in the atmosphere at Faisalabad, Pakistan. Their amount was two times higher than the limits adopted by the U.S. Environmental Protection Agency for the urban environment. (author)

  19. Current characteristic signals of aqueous solution transferring through microfluidic channel under non-continuous DC electric field

    Directory of Open Access Journals (Sweden)

    HongWei Ma

    2014-10-01

    Full Text Available The surface effect is becoming apparently significant as the miniaturization of fluidic devices. In the micro/nanochannel fluidics, the electrode surface effects have the same important influence on the current signals as the channel surface effects. In this paper, when aqueous solution are driven with non-continuous DC electric field force, the characteristics of current signals of the fluid transferring through microfluidic channel are systematically studied. Six modes of current signal are summarized, and some new significant phenomena are found, e.g. there exists a critical voltage at which the steady current value equals to zero; the absolute value of the steady current decreases at first, however, it increases with the external voltage greater than the critical voltage as the electrode area ratio of cathode and anode is 10 and 20; the critical voltage increases with the enhancing of electrode area ratio of cathode and anode and solution pH, while it decreases with the raising of ion concentration. Finally, the microscopic mechanism of the electrode surface charge effects is discussed preliminarily. The rules will be helpful for detecting and manipulating single biomolecules in the micro/nanofluidic chips and biosensors.

  20. The characteristics of atmospheric CO2 concentration variation of four national background stations in China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Through the non-dispersive infrared method, flask sampling of atmospheric CO2 concen- tration was measured weekly at four national background stations including Waliguan, Shangdianzi, Lin’an, and Longfengshan. Based on the data collected from September 2006 to August 2007, along with the Waliguan station’s experience on in situ observational data processing, the selection methods for sampling data through the atmospheric background CO2 concentration analysis were preliminarily discussed. On the basis of this result, the variation features of the four typical regions’ atmospheric background CO2 concentration was analyzed for the first time. The results show that the atmospheric CO2 concentration at Waliguan, Shangdianzi, Lin’an, and Longfengshan is 383.5, 385.9, 387.8, and 384.3 ppm, respectively. During the research period, CO2 concentration at the Waliguan station changed slightly. However, the CO2 concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones, and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis. The results from this study can lay the foundation for more profound studies on atmospheric CO2 concentration level of different areas in China, and could be used to improve the understanding of carbon source and sink distribution.

  1. GaSb p-channel metal-oxide-semiconductor field-effect transistor and its temperature dependent characteristics

    International Nuclear Information System (INIS)

    GaSb p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with an atomic layer deposited Al2O3 gate dielectric and a self-aligned Si-implanted source/drain are experimentally demonstrated. Temperature dependent electrical characteristics are investigated. Different electrical behaviors are observed in two temperature regions, and the underlying mechanisms are discussed. It is found that the reverse-bias pn junction leakage of the drain/substrate is the main component of the off-state drain leakage current, which is generation-current dominated in the low temperature regions and is diffusion-current dominated in the high temperature regions. Methods to further reduce the off-state drain leakage current are given. (paper)

  2. Dependence of positive and negative sprite morphology on lightning characteristics and upper atmospheric ambient conditions

    Science.gov (United States)

    Qin, Jianqi; Celestin, Sebastien; Pasko, Victor P.

    2013-05-01

    Carrot sprites, exhibiting both upward and downward propagating streamers, and columniform sprites, characterized by predominantly vertical downward streamers, represent two distinct morphological classes of lightning-driven transient luminous events in the upper atmosphere. It is found that positive cloud-to-ground lightning discharges (+CGs) associated with large charge moment changes (QhQ) tend to produce carrot sprites with the presence of a mesospheric region where the electric field exceeds the value 0.8Ek and persists for >˜2 ms, whereas those associated with small QhQ are only able to produce columniform sprites. Columniform sprites may also appear in the periphery of a sprite halo produced by +CGs associated with large QhQ. For a sufficiently large QhQ, the time dynamics of the QhQ determines the specific shape of the carrot sprites. In the case when the sufficiently large QhQ is produced mainly by an impulsive return stroke, strong electric field is produced at high altitudes and manifests as a bright halo, and the corresponding conductivity enhancement lowers/enhances the probability of streamer initiation inside/below the sprite halo. A more impulsive return stroke leads to a more significant conductivity enhancement (i.e., a brighter halo). This conductivity enhancement also leads to fast decay and termination of the upper diffuse region of carrot sprites because it effectively screens out the electric field at high altitudes. On the contrary, if the sufficiently large QhQ is produced by a weak return stroke (i.e., a dim halo) accompanied by intense continuing current, the lightning-induced electric field at high altitudes persists at a level that is comparable to Ek, and therefore an extensive upper diffuse region can develop. Furthermore, we demonstrate that `negative sprites' (produced by -CGs) should be necessarily carrot sprites and most likely accompanied by a detectable halo, since the initiation of upward positive streamers is always easier

  3. Characteristics of atmospheric particulate mercury in size-fractionated particles during haze days in Shanghai

    Science.gov (United States)

    Chen, Xiaojia; Balasubramanian, Rajasekhar; Zhu, Qiongyu; Behera, Sailesh N.; Bo, Dandan; Huang, Xian; Xie, Haiyun; Cheng, Jinping

    2016-04-01

    Atmospheric particulate mercury (PHg) is recognized as a global pollutant that requires regulation because of its significant impacts on both human health and wildlife. The haze episodes that occur frequently in China could influence the transport and fate of PHg. To examine the characteristics of PHg during haze and non-haze days, size-fractioned particles were collected using thirteen-stage Nano-MOUDI samplers (10 nm-18 μm) during a severe haze episode (from December 2013 to January 2014) in Shanghai. The PHg concentration on haze days (4.11 ± 0.53 ng m-3) was three times higher than on non-haze days (1.34 ± 0.15 ng m-3). The ratio of the PHg concentration to total gaseous mercury (TGM) ranged from 0.42 during haze days to 0.21 during non-haze days, which was possibly due to the elevated concentration of particles for gaseous elemental mercury (GEM) adsorption, elevated sulfate and nitrate contributing to GEM oxidation, and the catalytic effect of elevated water-soluble inorganic metal ions. PHg/PM10 during haze days (0.019 ± 0.004 ng/μg) was lower than during non-haze days (0.024 ± 0.002 ng/μg), and PHg/PM10 was significantly reduced with an increasing concentration of PM10, which implied a relatively lower growth velocity of mercury than other compositions on particles during haze days, especially in the diameter range of 0.018-0.032 μm. During haze days, each size-fractioned PHg concentration was higher than the corresponding fraction on non-haze days, and the dominant particle size was in the accumulation mode, with constant accumulation to a particle size of 0.56-1.0 μm. The mass size distribution of PHg was bimodal with peaks at 0.32-0.56 μm and 3.1-6.2 μm on non-haze days, and 0.56-1.0 μm and 3.1-6.2 μm on haze days. There was a clear trend that the dominant size for PHg in the fine modes shifted from 0.32-0.56 μm during non-haze days to 0.56-1.0 μm on haze days, which revealed the higher growth velocity of PHg on haze days due to the

  4. Characteristics of the atmospheric boundary layer in the Chos Malal site (Province of Neuquen)

    International Nuclear Information System (INIS)

    The site of Chos Malal is located on the north of the Province of Neuquen (Argentina).Cordillera del Viento is a mountain located 30 km northward, it is 90 km long, with average heights of 2800 m and with intense winds.This region has the adequate characteristics to be one of the best zones of the Norpatagonia for the exploitation of wind resources.Nevertheless, the existing wind speed data of the place is disconcerting.The biggest amount of information proceeds from the old weather station of the 'Secretaria de Agricultura y Ganaderia de la Nacion Argentina' Office and from the National Weather Service 'Servicio Meteorologico Nacional de Argentina' (SMN). Results from this data (1941-1960 period) shows that the mean annual wind speed is only 2.8 m/s.This value is conservative, probably due to the method employed on the measurement, which consisted of the estimation through the Beaufort scale, or the over-estimation error of the calms, as the one detected by Barros for the South of Patagonia.Due to this discordance, it was decided to evaluate the resource with modern instrumental. Afterwards, automatic weather stations were installed (Davis model Monitor II and Wizard) at the airport of Chos Malal (S 37 26 49; W 70 13 53; 852 m msl) with sensors at 2.5m, 10m and 18m above ground level.With this data (period 2000-2004) this study was oriented to characterize some aspects of the atmospheric boundary layer, the air turbulence and the relation between average wind speed and gusts.The annual average velocity (2000-2004) was 3.78 m/s, 35% greater than meteorological statistics from SMN (1941-1950 and 1951-1960 decades). The maximum velocity was 7.35 m/s, almost twice the average wind speed. With the measured data at 10 m, the Weibull distribution was calculated, using the form factor K = 1.2; and the scale factor C = 3.95. Also the wind rose was calculated, where the maximum frequency was produced at WNW.During 5 days of November of 2001, simultaneous observations at 2

  5. Extension of shelf-life of iced fresh channel catfish fillets using modified atmospheric packaging and low dose irradiation

    International Nuclear Information System (INIS)

    Fresh iced catfish fillets, processed with low dose irradiation (50-100 krad) in combination with modified atmosphere packaging were sampled every 10 days during 30-day storage period and analyzed for microbial load, color, and 2-thiobarbituric acid values (TBA) as indices of change in quality. No difference was observed between microbial counts of packages flushed with elevated carbon dioxide atmospheres (80:20 CO2/air, 100% CO2) and controls flushed with 100% air. Therefore, irradiation treatments with or without elevated carbon dioxide-modified atmospheric packaging significantly reduced the bacterial load and extended shelf-life from 5 to 7 days to between 20 and 30 days

  6. [Atmospheric Polybrominated Diphenyl Ethers in Eight Cities of China: Pollution Characteristics and Human Exposure].

    Science.gov (United States)

    Lin, Hai-tao; Li, Qi-lu; Zhang, Gan; Li, Jun

    2016-01-15

    The gas and particle samples of eight cities were collected by high flow active air sampler in the Eastern and Western China and eight congeners of polybrominated diphenyl ethers were analyzed. The results showed that the concentration of BDE-28 (tri-BDE) in the gas-phase (three bromide components) was the highest, which was different from previous studies where BDE-99 and-47 were the predominant homologues in the gas-phase while the concentration of BDE-209 [(25.4 ± 124) pg · m⁻³] in particle-phase was the highest. The atmospheric concentrations of PBDEs in Beijing and Guangzhou were relatively higher, especially the BDE-209 concentration in particle phases of Guangzhou was two orders higher than those of other cities. However, the atmospheric concentrations of PBDEs declined significantly when compared with the data from previous studies. Meanwhile, the results indicated that the gas-phase concentrations decreased slowly and the particle-phase concentrations decreased rapidly. Combined with the results of correlation analysis, this phenomenon might be ascribed to the ceased commercial production of penta- and octa-BDE, the light degradation of high bromide components and reduced concentrations of atmospheric particles in urban area. Inhalation exposure for infants was about 2-3 times higher than that of adults. This reflected that the potential health risk of atmospheric PBDEs in city for residents, especially infants and young children, should not be ignored. PMID:27078934

  7. Impacts of teachers’ competency on job performance in research universities with industry characteristics: Taking academic atmosphere as moderator

    Directory of Open Access Journals (Sweden)

    Anguo Xu

    2014-10-01

    Full Text Available Purpose: Research universities with industry characteristics play an irreplaceable role in national economic development and social development. With the rapid development of research universities with industry characteristics in China, these universities face new challenges in managing teachers and promoting their quality. This paper aims to examine the impact of teachers’ competency on job performance in research university with industry characteristics Design/methodology/approach: Based on the behavioral event interview and questionnaire methods, a four-dimension (i.e. basic quality, teaching ability, industry awareness and research capacity competency model was proposed, the influence mechanism of competency on job performance was examined using empirical research. Findings: We found that there is a significant positive correlation between the teachers’ competency level, four dimensions and job performance in research universities with industry characteristics, especially between research capacity, teaching ability, industry awareness and job performance. And academic atmosphere plays a regulatory role in the interaction between the competency and job performance. Practical implications: Our findings can help to improve the management level of teachers in research universities with industry characteristics.Originality/value: The paper introduces the competency theory to the teacher management in research universities with industry characteristics, and gives some interesting findings.

  8. Extraction of contact resistance and channel parameters from the electrical characteristics of a single bottom-gate/top-contact organic transistor

    Science.gov (United States)

    Takagaki, Shunsuke; Yamada, Hirofumi; Noda, Kei

    2016-03-01

    A parameter extraction procedure for staggered-type organic field-effect transistors (OFETs), in which only the electrical characteristics of a single device are needed, was newly considered. The existing differential method and the transition voltage method for evaluating contact and channel parameters in OFETs were complementarily combined. The calibration of the total resistance between the source and the drain was also incorporated to compensate discrepancies in the total resistances calculated from output and transfer characteristics, caused by the existence of nonignorable contact resistance and carrier traps. By using our proposed method, gate-voltage-dependent contact resistance and channel mobility in the linear regime were evaluated for bottom-gate/top-contact pentacene thin-film transistors, and the channel-length dependence of these parameters was investigated. A series of results of parameter extraction confirm the validity of our proposed method, which is advantageous in avoiding the influences of characteristic variations that are frequently observed in practical OFET devices.

  9. Determination of the Characteristics of Ground-Based IR Spectral Instrumentation for Environmental Monitoring of the Atmosphere

    Science.gov (United States)

    Makarova, M. V.; Poberovskii, A. V.; Hase, F.; Timofeyev, Yu. M.; Imhasin, Kh. Kh.

    2016-07-01

    This is a study of the spectral characteristics of a ground-based spectral system consisting of an original system for tracking the sun developed at St. Petersburg State University and a Bruker IFS125HR Fourier spectrometer. The importance of accounting for the actual instrument function of the spectral system during processing of ground-based IR spectra of direct solar radiation is illustrated by the example of determining the overall abundance of methane in the atmosphere. Spectral intervals are proposed for taking spectra of direct solar radiation with an HBr cell, which yield information on the parameters of the ground-based system, while simultaneously checking the alignment of the system for each spectrum of the atmosphere.

  10. A Maximum Likelihood Estimation of Vocal-Tract-Related Filter Characteristics for Single Channel Speech Separation

    Directory of Open Access Journals (Sweden)

    Dansereau Richard M

    2007-01-01

    Full Text Available We present a new technique for separating two speech signals from a single recording. The proposed method bridges the gap between underdetermined blind source separation techniques and those techniques that model the human auditory system, that is, computational auditory scene analysis (CASA. For this purpose, we decompose the speech signal into the excitation signal and the vocal-tract-related filter and then estimate the components from the mixed speech using a hybrid model. We first express the probability density function (PDF of the mixed speech's log spectral vectors in terms of the PDFs of the underlying speech signal's vocal-tract-related filters. Then, the mean vectors of PDFs of the vocal-tract-related filters are obtained using a maximum likelihood estimator given the mixed signal. Finally, the estimated vocal-tract-related filters along with the extracted fundamental frequencies are used to reconstruct estimates of the individual speech signals. The proposed technique effectively adds vocal-tract-related filter characteristics as a new cue to CASA models using a new grouping technique based on an underdetermined blind source separation. We compare our model with both an underdetermined blind source separation and a CASA method. The experimental results show that our model outperforms both techniques in terms of SNR improvement and the percentage of crosstalk suppression.

  11. A Maximum Likelihood Estimation of Vocal-Tract-Related Filter Characteristics for Single Channel Speech Separation

    Directory of Open Access Journals (Sweden)

    Mohammad H. Radfar

    2006-11-01

    Full Text Available We present a new technique for separating two speech signals from a single recording. The proposed method bridges the gap between underdetermined blind source separation techniques and those techniques that model the human auditory system, that is, computational auditory scene analysis (CASA. For this purpose, we decompose the speech signal into the excitation signal and the vocal-tract-related filter and then estimate the components from the mixed speech using a hybrid model. We first express the probability density function (PDF of the mixed speech's log spectral vectors in terms of the PDFs of the underlying speech signal's vocal-tract-related filters. Then, the mean vectors of PDFs of the vocal-tract-related filters are obtained using a maximum likelihood estimator given the mixed signal. Finally, the estimated vocal-tract-related filters along with the extracted fundamental frequencies are used to reconstruct estimates of the individual speech signals. The proposed technique effectively adds vocal-tract-related filter characteristics as a new cue to CASA models using a new grouping technique based on an underdetermined blind source separation. We compare our model with both an underdetermined blind source separation and a CASA method. The experimental results show that our model outperforms both techniques in terms of SNR improvement and the percentage of crosstalk suppression.

  12. Seasonal variability of physico-chemical characteristics of the Haldia channel of Hooghly estuary, India

    Indian Academy of Sciences (India)

    Y Sadhuram; V V Sarma; T V Ramana Murty; B Prabhakara Rao

    2005-02-01

    Physical and chemical characteristics of the Hooghly estuary during winter (December 1997-January 1998), summer (May 1998) and post-monsoon (November 1998) seasons have been stud-ied. Salinity varied spatially and temporally and seasonally during ebb and flood tide conditions. Water temperature showed a difference of 10°C in winter to summer. Temperature did not vary much vertically as it is a well-mixed estuary. Strong currents exceeding 100 cm s-1 were observed during peak ebb and flood tide conditions irrespective of the season. Longitudinal eddy diffusion coe±cient () was estimated as 757m s-1 and 811m2 s-1 during summer and post-monsoon sea-sons, respectively. The vertical eddy diffusion coefficient (v) was estimated as 0.0337m2 s-1 during post-monsoon season. The salinity and current observations are compared with those obtained from models reported earlier. Values of pH, Dissolved Oxygen and Biological Oxygen Demand are within the threshold limits of the estuarine environment. Nutrients show seasonal variation in the estuarine environment. High values (160-2686 mg l-1) of total suspended matter were noticed both at surface and bottom in the study region showing the impact of fresh water and sediment transportation.

  13. Comparison of analytical protein separation characteristics for three amine-based capillary-channeled polymer (C-CP) stationary phases.

    Science.gov (United States)

    Jiang, Liuwei; Marcus, R Kenneth

    2016-02-01

    Capillary-channeled polymer (C-CP) fiber stationary phases are finding utility in the realms of protein analytics as well as downstream processing. We have recently described the modification of poly(ethylene terephthalate) (PET) C-CP fibers to affect amine-rich phases for the weak anion-exchange (WAX) separation of proteins. Polyethylenimine (PEI) is covalently coupled to the PET surface, with subsequent cross-linking imparted by treatment with 1,4-butanediol diglycidyl ether (BUDGE). These modifications yield vastly improved dynamic binding capacities over the unmodified fibers. We have also previously employed native (unmodified) nylon 6 C-CP fibers as weak anion/cation-exchange (mixed-mode) and hydrophobic interaction chromatography (HIC) phases for protein separations. Polyamide, nylon 6, consists of amide groups along the polymer backbone, with primary amines and carboxylic acid end groups. The analytical separation characteristics of these three amine-based C-CP fiber phases are compared here. Each of the C-CP fiber columns in this study was shown to be able to separate a bovine serum albumin/hemoglobin/lysozyme mixture at high mobile phase linear velocity (∼70 mm s(-1)) but with different elution characteristics. These differences reflect the types of protein-surface interactions that are occurring, based on the active group composition of the fiber surfaces. This study provides important fundamental understanding for the development of surface-modified C-CP fiber columns for protein separation. PMID:26345444

  14. Performance of Wireless Optical Communication over Atmospheric Turbulence Channel%大气湍流下无线光通信信道性能研究

    Institute of Scientific and Technical Information of China (English)

    黄根全

    2011-01-01

    Based on different scintillation distribution channel model over atmospheric turbulence, the statistic model of outage probability and average channel capacity was founded,and the method on Gauss -Lager was applied to calculate outage probability and average channel capacity under weak to moderate and moderate to strong turbulence. The simulation results showed that outage probability increases with the increasing intensity of turbulence and normalized average electrical SNR, and average channel capacity also increases with the increasing of receiver average electrical SNR The increasing rate is faster and channel capacity is biger under weak turbulence than strong turbulence. The knowledge of the theory was provided for wireless optical access communication system.%无线光通信中大气湍流导致光信号在传输中产生光强起伏等现象,其影响成为无线光通信普及的一大障碍.基于大气湍流不同光强起伏信道模型,分别建立了弱、中及强湍流信道的中断概率与平均信道容量数学统计模型,研究了大气折射率结构常数和传输距离对湍流信道可靠性的影响.仿真结果表明,归一化阈值信噪比和通信距离的增加导致通信系统性能劣化.平均信道容量随着湍流强度的增大而降低,且随着接收机平均电信噪比增大,弱湍流下的信道容量增长速度明显大于强湍流.

  15. Study of the atmospheric aerosol composition and some characteristics by PIXE technique

    International Nuclear Information System (INIS)

    The atmospheric concentrations of Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Br, Se, As, Mg and Co in the vicinity of the coal-fired power station of Beijing and of two modern zinc-smelting plants in another province were determined by PIXE analysis, and their variations with time were followed. In addition, PIXE investigations of aerosols from three typical Beijing districts are reported. 5 refs, 10 figs, 9 tabs

  16. Characteristics of formation and growth of atmospheric nanoparticles observed at four regional background sites in Korea

    Science.gov (United States)

    Kim, Yumi; Kim, Sang-Woo; Yoon, Soon-Chang; Park, Jin-Soo; Lim, Jae-Hyun; Hong, Jihyung; Lim, Han-Cheol; Ryu, Jegyu; Lee, Chul-Kyu; Heo, Bok-Haeng

    2016-02-01

    Measurements of the number concentration and size distribution of atmospheric nanoparticles were conducted at four sites on the west coast of the Korean Peninsula by using identical scanning mobility particle sizers (SMPSs) in October 2012. The new particle formation and subsequent growth (NPF) of atmospheric nanoparticles, which were identified by the cyclostationary empirical orthogonal function (CSEOF) analysis technique, was observed on 11 out of 21 days at the Baengnyeong-do Comprehensive Monitoring Observatory (BCMO); and on 10 out of 21 days at the Korea Global Atmosphere Watch Center (KGAWC) from October 9 to 29, 2012. We also observed NPF events for 9 out of 21 days at both the Gosan Climate Observatory (GCO) and the Jeju Comprehensive Monitoring Observatory (JCMO). During the study period, NPF was simultaneously observed for five days at all four sites, which indicates that the NPF event had a spatial extent of at least 540 km. A cold, dry and cloud-free continental air mass originated from northern China, formed favorable environmental conditions (e.g., increasing solar insolation at the surface) on simultaneous NPF at the four sites. These synoptic weather patterns were closely associated with an extraordinary typhoon passing over the south of Japan. The mean values of particle formation rates at BCMO (1.26 cm- 3 s- 1) and KGAWC (1.49 cm- 3 s- 1) were relatively higher than those at GCO (0.39 cm- 3 s- 1) and JCMO (0.74 cm- 3 s- 1), however, the growth rate showed a similar level among four sites. An increase in the spatial homogeneity and inter-site correlation of atmospheric particles among the four sites was apparent for small particles (diameter < 30 nm) on simultaneous NPF event days.

  17. Characteristics of coupled atmosphere-ocean CO2 sensitivity experiments with different ocean formulations

    International Nuclear Information System (INIS)

    The Community Climate Model at the National Center for Atmospheric Research has been coupled to a simple mixed-layer ocean model and to a coarse-grid ocean general circulation model (OGCM). This paper compares the responses of simulated climate to increases of atmospheric carbon dioxide (CO2) in these two coupled models. Three types of simulations were run: (1) control runs with both ocean models, with CO2 held constant at present-day concentrations, (2) instantaneous doubling of atmospheric CO2 (from 330 to 660 ppm) with both ocean models, and (3) a gradually increasing (transient) CO2 concentration starting at 330 ppm and increasing linearly at 1% per year, with the OGCM. The mixed-layer and OGCM cases exhibit increases of 3.5 C and 1.6 C, respectively, in globally averaged surface air temperature for the instantaneous doubling cases. The transient-forcing case warms 0.7 C by the end of 30 years. The mixed-layer ocean yields warmer-than-observed tropical temperatures and colder-than-observed temperatures in the higher latitudes. The coarse-grid OGCM simulates lower-than-observed sea surface temperatures (SSTs) in the tropics and higher-than-observed SSTs and reduced sea-ice extent at higher latitudes. Sensitivity in the OGCM after 30 years is much lower than in simulations with the same atmosphere coupled to a 50-m slab-ocean mixed layer. The OGCM simulates a weaker thermohaline circulation with doubled CO2 as the high-latitude ocean-surface layer warms and freshens and the westerly wind stress decreases. Convective overturning in the OGCM decreases substantially with CO2 warming

  18. Characteristics of coupled atmosphere-ocean CO2 sensitivity experiments with different ocean formulations

    International Nuclear Information System (INIS)

    The Community Climate Model at the National Center for Atmospheric Research has been coupled to a simple mixed-layer ocean model and to a coarse-grid ocean general circulation model (OGCM). This paper compares the responses of simulated climate to increases of atmospheric carbon dioxide (CO2) in these two coupled models. Three types of simulations were run: (1) control runs with both ocean models, with CO2 held constant at present-day concentrations, (2) instantaneous doubling of atmospheric CO2 (from 330 to 660 ppm) with both ocean models, and (3) a gradually increasing (transient) CO2 concentration starting at 330 ppm and increasing linearly at 1% per year, with the OGCM. The mixed-layer and OGCM cases exhibit increases of 3.5 C and 1.6 C, respectively, in globally averaged surface air temperature for the instantaneous doubling cases. The transient-forcing case warms 0.7 C by the end of 30 years. The mixed-layer ocean yields warmer-than-observed tropical temperatures and colder-than-observed temperatures in the higher latitudes. The coarse-grid OGCM simulates lower-than-observed sea surface temperatures (SSTs) in the tropics and higher-than-observed SSTs and reduced sea-ice extent at higher latitudes. Sensitivity in the OGCM after 30 years is much lower than in simulations with the same atmosphere coupled to a 50-m slab-ocean mixed layer. The OGCM simulates a weaker thermohaline circulation with doubled CO2 as the high-latitude ocean-surface layer warms and freshens and the westerly wind stress decreases. Convective overturning in the OGCM decreases substantially with CO2 warming. 46 refs.; 20 figs.; 1 tab

  19. [Geochemical characteristics and sources of atmospheric particulates in Shanghai during dust storm event].

    Science.gov (United States)

    Qian, Peng; Zheng, Xiang-min; Zhou, Li-min

    2013-05-01

    Atmospheric particulates were sampled from three sampling sites of Putuo, Minhang and Qingpu Districts in Shanghai between Oct. , 2009 and Oct. , 2010. In addition, particulate samples were also collected from Nantong, Zhengzhou, Xi'an, and Beijing city where dust storm dust transported along during spring. Element compositions of atmospheric particulates were determined by XRF and ICP-MS. The concentrations of major and trace elements in atmospheric particulates from Putuo, Minhang and Qingpu Districts were similar, indicating their common source. The UCC standardization distribution map showed that the major element composition of dust storm samples was similar to that of loess in northwestern China, indicating that the dust storm dust was mainly derived from Western desert and partly from local area. The REE partition patterns of dust storm dusts among different cities along dust transport route were similar to each other, as well as to those of northern loess, which indicates that the dust storm samples may have the same material source as loess, which mainly comes from crust material. However, the REE partition patterns of non-dust storm particulates were different among the studied cities, and different from those of loess, which suggests that the non-dust storm samples may be mixed with non-crust source material, which is different from dust storm dust and loess. The major element composition and REE partition pattern are effective indicators for source tracing of dust storm dust. PMID:23914561

  20. Electrical Characteristics of Dielectric-Barrier Discharges in Atmospheric Pressure Air Using a Power-Frequency Voltage Source

    International Nuclear Information System (INIS)

    Dielectric-barrier discharges (DBDs) in atmospheric pressure air have been studied by using a power-frequency voltage source. In this paper the electrical characteristics of DBDs using glass and alumina dielectrics have been investigated experimentally. According to the Lissajous figures of voltage-charges, it is discovered that the discharge power for an alumina dielectric is much higher than that for a glass dielectric at the same applied voltage. Also, the voltage-current curves of the glass and alumina dielectrics confirm the fact that the dielectric barriers behave like semiconducting materials at certain applied voltages. (low temperature plasma)

  1. Study of Fading Characteristics of Evaporation Duct Channel for Microwave Over-the-Horizon Propagation%蒸发波导微波超视距信道衰落特性研究

    Institute of Scientific and Technical Information of China (English)

    王红光; 张利军; 郭相明; 吴振森

    2013-01-01

    For microwave over-the-horizon communication utilizing evaporation duct effects,a field experiment was carried out over three links of various path lengths.The fading amplitude,depth and speed of the channel were obtained at L,S,C and X frequency bands.A comparative analysis of the fast fading characteristics was made between evaporation duct and troposcatter channel.The path loss of measurements was compared with prediction according to the model of atmospheric duct and troposcatter propagation.The results show that evaporation duct channel has lower fading amplitude,depth and speed relative to the troposcatter channel,and the slow fading characteristics can be predicted by the propagation model effectively.%针对利用海上蒸发波导效应的微波超视距通信,在三条不同距离跨海电路上开展了外场试验.基于测试数据,统计L、S、C和X频段超视距信道的衰落幅度、深度和速率,对比分析了蒸发波导和对流层散射信道的快衰落特性.并根据大气波导和对流层散射传播预测模型,统计比较了实测和模型预测路径传播损耗.结果表明与对流层散射信道相比,蒸发波导信道衰落幅度、衰落深度和衰落速率均较小,传播预测模型可有效的预测蒸发波导的慢衰落特性.

  2. Characteristics of atmospheric CO2 and CH4 at the Shangdianzi regional background station in China

    Science.gov (United States)

    Fang, Shuang-xi; Tans, Pieter P.; Dong, Fan; Zhou, Huaigang; Luan, Tian

    2016-04-01

    Atmospheric CO2 and CH4 have been continuously measured at the Shangdianzi regional background station (SDZ) in China from 2009 to 2013. Based on the influences of local surface wind and long-distance transport, the observed records were flagged into locally influenced, Beijing-Tianjin-Hebei (BTH) influenced, and Russia, Mongolia, and Inner Mongolia autonomous region influenced (RMI). ∼ 81.4% of CO2 and ∼75.6% of CH4 mole fractions were flagged as locally representative, indicating that the atmospheric CO2 and CH4 at SDZ were strongly influenced by local sources and sinks. Cluster analysis of back trajectories proved that the atmospheric CO2 and CH4 were influenced by air masses from northwest (RMI) or from south and southeast (BTH). The CO2 and CH4 mole fractions in BTH are always higher than in RMI, with the largest difference of 11.5 ± 0.3 ppm for CO2 and 102 ± 1 ppb for CH4 in July. The annual growth rates of CO2 and CH4 in BTH are 3.8 ± 0.01 ppm yr-1 and 10 ± 0.1 ppb yr-1, respectively, which are apparently higher than those of the RMI and the global means. The long-term trends of CO2 and CH4 in BTH are deviating from those in RMI, with ratios of ∼1.0 ppm yr-1 for CO2 and ∼2 ppb yr-1 for CH4, indicating the strengths of CO2 and CH4 emission in Beijing-Tianjin-Hebei plain increased more than 20% every year.

  3. Characteristic of Tweek Atmospherics Observed in Mid-latitude using AWESOME VLF Receiver

    OpenAIRE

    Norbayah Yusop; Nor Azlan Mohd Aris; S.A.M. Chachuli; Maizatul Alice Meor Said

    2014-01-01

    This study presents the analysis of tweek atmospherics received by AWESOME VLF receiver at station of Gakona (62.71°N, 143.99°W) during four months observation from January to April 2011. Tweek which originates from lightning discharge are used to monitor the nighttime D-region ionosphere using the fundamental cut-off frequency to measure the variations of the lower ionosphere’s reflection height, the equivalent electron density at the reflection height and the propagation distance travel by ...

  4. Forest condition and chemical characteristics of atmospheric depositions: research and monitoring network in Lombardy

    Directory of Open Access Journals (Sweden)

    Flaminio DI GIROLAMO

    2002-09-01

    Full Text Available Since 1987, the Regional Forestry Board of Lombardy and the Water Research Institute of the National Research Council have been carrying out surveys of forest conditions and the response of the ecosystem to environmental factors. The study approach is based on a large number of permanent plots for extensive monitoring (Level 1. At this level, crown condition is assessed annually, and soil condition and the nutritional status of forests surveyed. Some of the permanent plots were selected for intensive monitoring (Level 2, focussing mainly on the impact of atmospheric pollution on forest ecosystems. Level 2 monitoring also includes increment analyses, ground vegetation assessment, atmospheric deposition, soil solution analyses and climatic observations. This paper summarises the main results of a pluriannual research, which provides a general picture of the state of forest health in the region and focuses on more detailed investigations, described as case studies. Modified wet and dry samplers which use a water surface to collect dry deposition were used in a pluriannual field campaign at five sites in alpine and prealpine areas, to measure the total atmospheric depositions and to evaluate the nitrogen and sulphate exceedances of critical loads. Throughfall and bulk precipitation chemistry were studied for five years (June 1994-May 1999 at two high elevation forest sites (Val Gerola and Val Masino which were known to differ in terms of tree health, as assessed by live crown condition. Results indicated a higher contribution from the dry deposition of N-NO3 -, N-NH4 + and H+ and considerable canopy leaching of Ca2+, K+ and weak organic acids at Val Gerola, where the symptoms of damage were more evident. In the area of Val Masino (SO, included since 1997 in the national CONECOFOR network, investigations focused on the effectiveness of the biological compartment in modifying fluxes of atmospheric elements, and on the role of nitrogen both as an

  5. Characteristics of acoustic wave from atmospheric nuclear explosions conducted at the USSR Test Sites

    Science.gov (United States)

    Sokolova, Inna

    2015-04-01

    Availability of the acoustic wave on the record of microbarograph is one of discriminate signs of atmospheric (surface layer of atmosphere) and contact explosions. Nowadays there is large number of air wave records from chemical explosions recorded by the IMS infrasound stations installed during recent decade. But there is small number of air wave records from nuclear explosions as air and contact nuclear explosions had been conducted since 1945 to 1962, before the Limited Test Ban Treaty was signed in 1963 (the treaty banning nuclear weapon tests in the atmosphere, in outer space and under water) by the Great Britain, USSR and USA. That time there was small number of installed microbarographs. First infrasound stations in the USSR appeared in 1954, and by the moment of the USSR collapse the network consisted of 25 infrasound stations, 3 of which were located on Kazakhstan territory - in Kurchatov (East Kazakhstan), in Borovoye Observatory (North Kazakhstan) and Talgar Observatory (Northern Tien Shan). The microbarograph of Talgar Observatory was installed in 1962 and recorded large number of air nuclear explosions conducted at Semipalatinsk Test Site and Novaya Zemlya Test Site. The epicentral distance to the STS was ~700 km, and to Novaya Zemlya Test Site ~3500 km. The historical analog records of the microbarograph were analyzed on the availability of the acoustic wave. The selected records were digitized, the database of acoustic signals from nuclear explosions was created. In addition, acoustic signals from atmospheric nuclear explosions conducted at the USSR Test Sites were recorded by analogue broadband seismic stations at wide range of epicentral distances, 300-3600 km. These signals coincide well by its form and spectral content with records of microbarographs and can be used for monitoring tasks and discrimination in places where infrasound observations are absent. Nuclear explosions which records contained acoustic wave were from 0.03 to 30 kt yield for

  6. Influence of physicochemical water characteristics in the transport of methane to the atmosphere at Rodrigo de Freitas lagoon, RJ

    Directory of Open Access Journals (Sweden)

    Plínio Carlos Alvalá

    2012-12-01

    Full Text Available The accumulation and decomposition of organic matter in water bodies can increase the potential emission of greenhouse gases to the atmosphere. In this study, in a prospective and exploratory way, we evaluated the relationship between physicochemical characteristics of water on the transport of methane to the atmosphere at Rodrigo de Freitas lagoon, RJ. In 2011, campaigns were carried out in which 200 samples were collected for analysis of superficial methane emission and 30 water samples were collected to verify the dissolution of this gas in the water column, measuring simultaneously both the physicochemical water parameters along this column. The methane flow measurements showed that this lagoon is a source methane emission to the atmosphere with an average flux of 33 ± 10 mgCH4m-2d-1. The evaluation of limnological parameters that could affect the emission flux revealed that the water depth and temperature were the most influential factors in this process. A profile analysis of methane in the water column suggests the existence of a higher concentration of this gas in the region of the sedimentary strata at the bottom of the lagoon. However, the potential emission may not reach the surface, possibly due to the decrease in the rate of vertical diffusion of methane, as a result of the increase of pressure with depth and the presence of methanotrophic bacterias that consume methane throughout the water column.

  7. Assessments of F16 Special Sensor Microwave Imager and Sounder Antenna Temperatures at Lower Atmospheric Sounding Channels

    OpenAIRE

    Fuzhong Weng; Banghua Yan

    2009-01-01

    The main reflector of the Special Sensor Microwave Imager/Sounder (SSMIS) aboard the Defense Meteorological Satellite Program (DMSP) F-16 satellite emits variable radiation, and the SSMIS warm calibration load is intruded by direct and indirect solar radiation. These contamination sources produce antenna brightness temperature anomalies of around 2 K at SSMIS sounding channels which are obviously inappropriate for assimilation into numerical weather prediction models and remote sensing retrie...

  8. Non-Stoichiometry and Vaporization Characteristic of Li2.1TiO3.05 under Hydrogen Atmosphere

    International Nuclear Information System (INIS)

    Li2TiO3 is one of the most promising candidates among the proposed solid breeder materials in fusion reactors because of its chemical satiability. Addition of H2 to inert sweep gas has been proposed for enhancing the release of bred tritium from breeder material. However, the mass of Li2TiO3 was found to decrease with time in the hydrogen atmosphere. This mass-change indicates that the oxygen content of the sample decreased, suggesting the change from Ti4+ to Ti3+ and the partial pressures of Li containing species were increased. In order to control the mass-change at the time of high temperature use, the development of Li2TiO3 which has Li2O additive is needed. Furthermore, since Li2TiO3 is reduced in hydrogen atmosphere, it is important to investigate the reduction characteristic with Li2O addition. In the present paper, the non-stoichiometry and vaporization characteristic of Li2TiO3 added with Li2O have been extensively investigated by means of thermogravimetry and atmosphere-controlled high-temperature mass spectrometry. In the case of the Li2TiO3 samples used by the present study, Li2CO3 and TiO2 powders were mixed in the proportions corresponding to the molecular ratio Li2O/TiO2 of either 1.00 or 1.05. These samples are designated as L100 (Li2TiO3), and L105 (Li2.1TiO3.05), respectively. In thermogravimetry, the masses of L100 and L105 were found to decrease with time in the hydrogen atmosphere, then to increase after the change of the atmosphere from hydrogen to oxygen. The color was observed to change from white to thin light-brown under the hydrogen atmosphere. This color-change indicates that the oxygen content of the sample decreased, suggesting the change from Ti4+ to Ti3+. Further, L105 has fewer oxygen defects than L100. L105 has the smaller mass of TiO2 in Li2TiO3, so that the order of oxygen defects was as follows, L105 2 atmospheres. In case of adding D2 gas, Li(g), LiOD(g), Li2O(g) D2(g) and D2O(g) were identified as the vapor species. The sum of

  9. Asymmetric surface dielectric barrier discharge in air at atmospheric pressure: electrical properties and induced airflow characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Pons, Jerome; Moreau, Eric; Touchard, Gerard [LEA, University of Poitiers/CNRS/ENSMA, Bd. Curie, Teleport 2, BP 30179, 86962 Futuroscope Cedex (France)

    2005-10-07

    The electrical properties of an asymmetric surface dielectric barrier discharge in atmospheric air have been investigated experimentally. The discharge is used for airflow production close to the dielectric surface, and the time-averaged flow velocity spatial profiles have been measured. Velocities of up to 3.5 m s{sup -1} at heights of 1-2 mm are reached when filamentary discharges with current peaks up to 20 mA are produced along the surface. In terms of powers, mechanical powers (output) of a few milliwatts are obtained for electrical powers (input) up to 10 W. Variation laws or behaviour with several discharge parameters (applied voltage waveform, distance between electrodes, dielectric thickness and permittivity) have been experimentally determined.

  10. Combined effects of gamma irradiation and a modified atmospheric packaging on the physicochemical characteristics of sausage

    International Nuclear Information System (INIS)

    This study is to investigate the combined effects of irradiation and a modified atmospheric packaging (MAP) on the color, nitrosoheme pigments (NO-Mb), residual nitrite and N-nitrosodimethylamine (NDMA) in sausage during storage. Sausage with air, vacuum, CO2, N2, or CO2/N2 packaging was irradiated at 5 kGy. Irradiation reduced the red color of sausage, and a vacuum or MAP was effective in minimizing the loss of redness. The reduction of NO-Mb was observed by irradiation, while the MAP was more effective in maintaining the NO-Mb than the aerobic ones. Residual nitrite was reduced by irradiation, and the contents were lower under vacuum or MAP than aerobic ones. NDMA was significantly reduced by irradiation

  11. Characteristics of Ozone Production by Using Atmospheric Surface Glow Barrier Discharge

    Directory of Open Access Journals (Sweden)

    Mudtorlep NISOA

    2009-06-01

    Full Text Available Ozone is a strong oxidizer that can kill bacteria and other micro-organisms very effectively. In the recent years, ozone has become very important for sterilization of water used in shrimp farming and treatment of wastewater from food industry. However, ozonisers available in the markets are very expensive and have low energy-efficiency. In this work, a highly-efficient and low-cost system that can produce high-concentrations of ozone gas and dissolved ozone in water has been developed. The system consists of a dried air unit, high-voltage rf power supply, ozoniser tubes and venturi injector. The tubes are designed and configured to convert oxygen gas to ozone gas by atmospheric surface glow barrier discharge.

  12. Characteristics of the hadron and gamma-ray families at various altitudes in atmosphere

    International Nuclear Information System (INIS)

    The gamma-ray families detected in the X-ray chambers may be produced by the different numbers of the elementary interactions in the cosmic shower. The reconstruction of the cosmic cascade development and the extraction of the information of elementary interactions at high energies is then very difficult and ambiguous. The problem of cascade development dependency on the altitude of its beginning is investigated. Comparisons of the computed cascades characteristics with the experimental data are presented. (S.B.)

  13. Designing an experimental loop for studying the heat transfer characteristics of porous media channels with strong heat source

    International Nuclear Information System (INIS)

    Water-cooled pebble-bed reactor is a new conception reactor which owns the excellences of the spherical fuel and the water-cooled reactor. It is very safe and economical. On the background of water-cooled pebble-bed reactor, an experimental loop with porous media channel was designed to study the characteristics of forced convection heat transfer with strong heat source. It uses water as flowing media, and the test section is packed with oxidized stainless steel spheres. The non-contact electromagnetic induction heating method was used in the loop, and because of its inherent weakness, some methods for solving these problems were obtained by theoretical calculation and simulation combined with considering the relationship of radius with the electrical current permeation deepness, the intensity of magnetic field, the character of material as well as the structure design, and finish the loop. It will be helpful for conducting the relevant research with respect to the water-cooled pebble-bed reactor. (authors)

  14. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    Science.gov (United States)

    Petzold, A.; Hasselbach, J.; Lauer, P.; Baumann, R.; Franke, K.; Gurk, C.; Schlager, H.; Weingartner, E.

    2008-05-01

    Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL) were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transformation studies in the plume of a large container ship in the English Channel using the DLR aircraft Falcon 20 E-5. Observations from emission studies and plume studies combined with a Gaussian plume dispersion model yield a consistent picture of particle transformation processes from emission to atmospheric processing during plume expansion. Particulate matter emission indices obtained from plume measurements are 8.8±1.0×1015(kg fuel)-1 by number for non-volatile particles and 174±43 mg (kg fuel)-1 by mass for Black Carbon (BC). Values determined for test rig conditions between 85 and 110% engine load are of similar magnitude. For the total particle number including volatile compounds no emission index can be derived since the volatile aerosol fraction is subject to rapid transformation processes in the plume. Ship exhaust particles occur in the size range Dpemissions to 0.10 μm at a plume age of 1 h. The smaller-sized volatile particle mode is centred at Dp≤0.02 μm. From the decay of ship exhaust particle number concentrations in an expanding plume, a maximum plume life time of approx. 24 h is estimated for a well-mixed marine boundary layer.

  15. Computer Simulation Studies of Ion Channel Gating: Characteristics of the M2 Channel of Influenza-A Virus in a Phospholipid Bilayer

    Science.gov (United States)

    Schweighofer, Karl J.; Pohorille, Andrew; DeVincenzi, D. (Technical Monitor)

    1999-01-01

    The 25 amino acids long, transmembrane fragment of the Influenza virus M2 protein forms a homotetrameric channel that transports protons across lipid bilayers. It has been postulated that high efficiency and selectivity of this process is due to gating by four histidine residues that occlude the channel lumen in the closed state. Two mechanisms of gating have been postulated. In one mechanism, the proton is "shuttled" through the gate by attaching to the delta nitrogen atom on the extracellular side of the imidazole ring, followed by the release of the proton attached to the epsilon nitrogen atom on the opposite side. In the second mechanism, the four histidines move away from each other due to electrostatic repulsion upon protonation, thus opening the gate sufficiently that a wire of water molecules can penetrate the gate. Then, protons are transported by "hopping" along the wire. In this paper, both mechanisms are evaluated in a series of molecular dynamics simulations by investigating stability of different protonation states of the channel that are involved in these mechanisms. For the shuttle mechanism, these are states with all epsilon protonated histidines, one biprotonated residue or one histidine protonated in the delta position. For the gate opening mechanism, this is the state in which all four histidines are biprotonated. In addition, a state with two biprotonated histidines is considered. For each system, composed of the protein channel embedded in phospholipid bilayer located between two water lamellae, a molecular dynamics trajectory of approximately 1.3 ns (after equilibration) was obtained. It is found that the states involved in the shuttle mechanism are stable during the simulations. Furthermore, the orientations and dynamics of water molecules near the gate are conducive to proton transfers involved in the shuttle. In contract, the fully biprotonated state, implicated in the gate opening mechanism, is not stable and the channel looses its

  16. Some characteristics of atmospheric gravity waves observed by radio-interferometry

    Directory of Open Access Journals (Sweden)

    Claude Mercier

    Full Text Available Observations of atmospheric acoustic-gravity waves (AGWs are considered through their effect on the horizontal gradient G of the slant total electron content (slant TEC, which can be directly obtained from two-dimensional radio-interferometric observations of cosmic radio-sources with the Nançay radioheligraph (2.2°E, 47.3°N. Azimuths of propagation can be deduced (modulo 180°. The total database amounts to about 800 h of observations at various elevations, local time and seasons. The main results are:

    a AGWs are partially directive, confirming our previous results.

    b The propagation azimuths considered globally are widely scattered with a preference towards the south.

    c They show a bimodal time distribution with preferential directions towards the SE during daytime and towards the SW during night-time (rather than a clockwise rotation as reported by previous authors.

    d The periods are scattered but are larger during night-time than during daytime by about 60%.

    e The effects observed with the solar radio-sources are significantly stronger than with other radio-sources (particularly at higher elevations, showing the role of the geometry in line of sight-integrated observations.

  17. Characteristics of SAO and AO in equatorial middle atmospheric temperature pattern

    International Nuclear Information System (INIS)

    Complete text of publication follows. More than 10 years (1998-2008) of data from a low latitude station, Gadanki, India (13.5deg N, 79.2deg E), has been utilized to measure middle atmospheric temperature pattern, using lidar and TIMED/SABER, which exhibits the presence of semi-annual oscillation (SAO) and annual oscillation (AO). AO component is stronger in mesospheric region (80-90 km) and SAO is dominant at stratospheric altitudes (30-50 km). Overall, AO possesses higher amplitude ∼ 6 K, and SAO shows relatively less amplitude ∼ 1-2 K. AO at 90 km, has its crest around summer solstice, and the same at 80 shows peak around winter solstice with a downward progression speed ∼ 1.67 km/month. SAO propagates downward with an average phase speed ∼ 7 km/month and its phase maximizes around equinox and solstice at 50 and 30 km, respectively. Observed SAO has also shown seasonal asymmetry in the peak.

  18. Characteristics of Spatiotemporally Homogenized Boundary Layers at Atmospheric Reentry-like Conditions

    Science.gov (United States)

    Ulerich, Rhys; Moser, Robert

    2014-11-01

    Turbulent boundary layers approximating those found on the NASA Orion Multi-Purpose Crew Vehicle thermal protection system during atmospheric reentry from the International Space Station have been studied by direct numerical simulation using a ``slow growth'' spatiotemporal homogenization approach recently developed by Topalian et al. The two data sets generated were Mae ~ 0 . 9 and 1 . 15 homogenized boundary layers possessing Reθ ~ 382 and 531, respectively. Edge-to-wall temperature ratios were approximately 4.15 and wall blowing velocities, vw+ =vw /uτ , were roughly 8 ×10-3 . The favorable pressure gradients had Pohlhausen parameters between 25 and 42. Nusselt numbers under 22 were observed. Small or negative displacement effects are evident. Near-wall vorticity fluctuations show qualitatively different profiles than observed by Spalart [J. Fluid Mech. 187 (1988)] or Guarini et al. [J. Fluid Mech. 414 (2000)] suggesting that the simulations have atypical structures perhaps as a consequence of wall blowing or the homogenization. This material is based in part upon work supported by the Department of Energy [National Nuclear Security Administration] under Award Number [DE-FC52-08NA28615].

  19. Effect of packaging atmospheres on storage quality characteristics of heavily marbled beef longissimus steaks.

    Science.gov (United States)

    Yang, Xiaoyin; Zhang, Yimin; Zhu, Lixian; Han, Mingshan; Gao, Shujuan; Luo, Xin

    2016-07-01

    The objective of this study was to investigate the effects of modified atmosphere packaging (MAP) systems on shelf-life and quality of beef steaks with high marbling. Four packaging types were used including 80% O2 MAP (80% O2+20% CO2), 50% O2 MAP (50% O2+30% CO2+20% N2), carbon monoxide MAP (0.4% CO+30% CO2+69.6% N2) and vacuum packaging (VP). Steaks were displayed under simulated retail conditions at 4°C for 12days. Purge loss, pH, color stability, oxidative stability and microbial counts were monitored. Aerobically packaged steaks exhibited a bright-red color at the first 4days. However, discoloration and oxidation became major factors limiting their shelf-life to 8days. Compared with aerobic packaging, anaerobic packaging extended shelf-life of heavily marbled beef steaks, due to better color stability, together with lower oxidation and microbial populations. Among all packaging methods, CO-MAP had the best preservation for steaks, with more red color than other packaging types. PMID:26946476

  20. Characteristic of Tweek Atmospherics Observed in Mid-latitude using AWESOME VLF Receiver

    Directory of Open Access Journals (Sweden)

    Norbayah Yusop

    2014-03-01

    Full Text Available This study presents the analysis of tweek atmospherics received by AWESOME VLF receiver at station of Gakona (62.71°N, 143.99°W during four months observation from January to April 2011. Tweek which originates from lightning discharge are used to monitor the nighttime D-region ionosphere using the fundamental cut-off frequency to measure the variations of the lower ionosphere’s reflection height, the equivalent electron density at the reflection height and the propagation distance travel by tweeks. In this study, a total of 1316 tweeks are analyzed and from the analysis, it shows that equinox’s season has the highest tweek occurrence compared to winter season in March and April. The maximum harmonic (m of t weeks is found to be up to fourth ( m = 4 and tweeks with mode number one (m = 1 are more dominantly occurred. Our observations indicate that the equivalent electron densities for tweeks varies from 22-27 eL/cm3 in the altitude ranged of 75 to 91 km and demonstrate that these ELF/VLF signals travel considerable distances up to 6700 km from the causative lightning discharges. The ionospheric parameters for three locations (high, middle and low latitude respectively were compared and the results show that they are almost consistent for all the locations.

  1. Chemical characteristics and source of size-fractionated atmospheric particle in haze episode in Beijing

    Science.gov (United States)

    Tan, Jihua; Duan, Jingchun; Zhen, Naijia; He, Kebin; Hao, Jiming

    2016-01-01

    The abundance, behavior, and source of chemical species in size-fractionated atmospheric particle were studied with a 13-stage low pressure impactor (ELPI) during high polluted winter episode in Beijing. Thirty three elements (Al, Ca, Fe, K, Mg, Na, Si, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Sr, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, and Pb) and eight water soluble ions (Cl-, NO3-, SO42 -, NH4+, Na+, K+, Ca2 +, and Mg2 +) were determined by ICP/MS and IC, respectively. The size distribution of TC (OC + EC) was reconstructed. Averagely, 51.5 ± 5.3% and 74.1 ± 3.7% of the total aerosol mass was distributed in the sub-micron (PM1) and fine particle (PM2.5), respectively. A significant shift to larger fractions during heavy pollution episode was observed for aerosol mass, NH4+, SO42 -, NO3-, K, Fe, Cu, Zn, Cd, and Pb. The mass size distributions of NH4+, SO42 -, NO3-, and K were dominated by accumulation mode. Size distributions of elements were classified into four main types: (I) elements were enriched within the accumulation mode (water soluble ions. Dust, vehicle, aged coal combustion, and sea salt were identified, and the size resolved source apportionments were discussed. Aged coal combustion was the important source of fine particles and dust contributed most to coarse particle.

  2. Experimental Attempts to Investigate the Influence of Petrographic Properties on Drying Characteristics of Lignite in Superheated Steam Atmosphere

    Directory of Open Access Journals (Sweden)

    Anna Sciazko

    2016-05-01

    Full Text Available A superheated steam fluidized bed dryer (SSFBD in a self-heat recuperative configuration has a great potential of improving thermal efficiency of a lignite-fired power plant by recovering both of latent heat of vaporization of water kept in the fuel and part of sensible heat during the fuel processing. However, the optimal design of the dryer requires the fundamental knowledge of drying characteristics in respect to the individual properties of the utilized fuel. Experimental investigation to determine the correlation between a specific coal properties originated from geological background and its drying characteristics is thus the major concern in this paper. The investigated lignite is a representative of Turoszow deposit in Poland. Experimental attempts unveiling drying kinetics were carried out for 5 mm and 10 mm diameter spherical samples in the superheated steam atmosphere in the temperature range of 110 °C–170 °C. Simultaneous and continuous measurements of changes in weight, surface and interior temperatures and appearance on each tested sample were carried out for describing drying behavior. Analytical investigation was applied to explain the drying characteristics, which are strongly affected by the individual properties of coal and the inherent ash composition.

  3. Characteristics and Composition of Atmospheric Aerosols in Phimai, Central Thailand During BASE-ASIA

    Science.gov (United States)

    Li, Can; Tsay, Si-Chee; Hsu, N. Christina; Kim, Jin Young; Howell, Steven G.; Huebert, Barry J.; Ji, Qiang; Jeong, Myeong-Jae; Wang, Sheng-Hsiang; Hansell, Richard A.; Bell, Shaun W.

    2012-01-01

    Popular summary: Atmospheric aerosols play an important role in the Earth's climate system, and can also have adverse effects on air quality and human health. The environmental impacts of aerosols, on the other hand, are highly regional, since their temporal/spatial distribution is inhomogeneous and highly depends on the regional emission sources. To better understand the effects of aerosols, intensive field experiments are necessary to characterize the chemical and physical properties on a region-by-region basis. From late February to early May in 2006, NASA/GSFC's SMARTLabs facility was deployed at a rural site in central Thailand, Southeast Asia, to conduct a field experiment dubbed BASE-ASIA (Biomass-burning Aerosols in South East-Asia: Smoke Impact Assessment). The group was joined by scientists from the University of Hawaii and other regional institutes. Comprehensive measurements were made during the experiment, including aerosol chemical composition, optical and microphysical properties, as well as surface energetics and local . meteorology. This study analyzes part of the data from the BASE-ASIA experiment. It was found that, even for the relatively remote rural site, the aerosol loading was still substantial. Besides agricultural burning in the area, industrial pollution near the Bangkok metropolitan area, about 200 km southeast of the site, and even long-range transport from China, also contribute to the area's aerosol loading. The results indicate that aerosol pollution has developed into a regional problem for northern Indochina, and may become more severe as the region's population and economy continue to grow. Abstract: Comprehensive measurements of atmospheric aerosols were made in Phimai, central Thailand (15.l83 N, 102.565 E, elevation: 206 m) during the BASE-ASIA field experiment from late February to early May in 2006. The observed aerosol loading was sizable for this rural site (mean aerosol scattering: 108 +/- 64 Mm(exp -1); absorption: 15

  4. Morphological and chemical composition characteristics of summertime atmospheric particles collected at Tokchok Island, Korea

    Science.gov (United States)

    Geng, Hong; Jung, Hae-Jin; Park, YooMyung; Hwang, HeeJin; Kim, HyeKyeong; Kim, Yoo Jung; Sunwoo, Young; Ro, Chul-Un

    Determination of the chemical compositions of atmospheric single particles in the Yellow Sea region is critical for evaluating the environmental impact caused by air pollutants emitted from mainland China and the Korean peninsula. After ambient aerosol particles were collected by the Dekati PM10 cascade impactor on July 17-23, 2007 at Tokchok Island (approximately 50 km west of the Korean coast nearby Seoul), Korea, overall 2000 particles (on stage 2 and 3 with cut-off diameters of 2.5-10 μm and 1.0-2.5 μm, respectively) in 10 samples were determined by using low- Z particle electron probe X-ray microanalysis. X-ray spectral and secondary electron image (SEI) data showed that soil-derived and sea-salt particles which had reacted or were mixed with SO 2 and NO x (or their acidic products) outnumbered the primary and "genuine" ones (59.2% vs. 19.2% in the stage 2 fraction and 41.3% vs. 9.9% in the stage 3 fraction). Moreover, particles containing nitrate in the secondary soil-derived species greatly outnumbered those containing sulfate. Organic particles, mainly consisting of marine biogenic species, were more abundant in the stage 2 fraction than in the stage 3 fraction (11.6% vs. 5.1%). Their relative abundance was greater than the sum of carbon-rich, K-containing, Fe-containing, and fly ash particles, which exhibited low frequencies in all the samples. In addition, many droplets rich in C, N, O, and S were observed. They tended to be small, exhibiting a dark round shape on SEI, and generally included 8-20 at.% C, 0-12 at.% N, 60-80 at.% O, and 4-10 at.% S (sometimes with secondary aerosol particles.

  5. Characteristics and sources of polycyclic aromatic hydrocarbons in atmospheric aerosols in the Kathmandu Valley, Nepal.

    Science.gov (United States)

    Chen, Pengfei; Kang, Shichang; Li, Chaoliu; Rupakheti, Maheswar; Yan, Fangping; Li, Quanlian; Ji, Zhenming; Zhang, Qianggong; Luo, Wei; Sillanpää, Mika

    2015-12-15

    The Kathmandu Valley in the foothills of the Himalayas, where the capital city of Nepal is located, has one of the most serious air pollution problems in the world. In this study, total suspended particle (TSP) samples collected over a year (April 2013-March 2014) in the Kathmandu Valley were analyzed for determining the concentrations of 15 priority particle-bound polycyclic aromatic hydrocarbons (PAHs). The TSP and PAH concentrations were extremely high, with annual average concentration being 199±124μg/m(3) and 155±130ng/m(3), respectively, which are comparable to those observed in Asian cities such as Beijing and Delhi. The TSP and PAH concentrations varied considerably, with the seasonal average concentration being maximal during the post-monsoon season followed by, in descending order, the winter, pre-monsoon, and monsoon seasons. In the winter and pre-monsoon seasons, ambient TSP and PAH concentrations increased because of emissions from brick kilns and the use of numerous small generators. Moreover, in the pre-monsoon season, forest fires in the surrounding regions influenced the TSP and PAH concentrations in the valley. PAHs with 4 to 6 rings constituted a predominant proportion (92.3-93.3%) of the total PAHs throughout the year. Evaluation of diagnostic molecular ratios indicated that the atmospheric PAHs in the Kathmandu Valley originated mainly from diesel and biomass combustion. The toxic equivalent quantity (TEQ) of particle phase PAHs ranged between 2.74 and 81.5ngTEQ/m(3), which is considerably higher than those reported in other South Asian cities, and 2-80 times higher than the World Health Organization guideline (1ngTEQ/m(3)). This suggests that ambient PAH levels in the Kathmandu Valley pose a serious health risk to its approximately 3.5 million residents. PMID:26298251

  6. Characteristics of the atmospheric CO2 signal as observed over the conterminous United States during INTEX-NA

    Science.gov (United States)

    Choi, Yonghoon; Vay, Stephanie A.; Vadrevu, Krishna P.; Soja, Amber J.; Woo, Jung-Hun; Nolf, Scott R.; Sachse, Glen W.; Diskin, Glenn S.; Blake, Donald R.; Blake, Nicola J.; Singh, Hanwant B.; Avery, Melody A.; Fried, Alan; Pfister, Leonhard; Fuelberg, Henry E.

    2008-04-01

    High resolution in situ measurements of atmospheric CO2 were made from the NASA DC-8 aircraft during the Intercontinental Chemical Transport Experiment-North America (INTEX-NA) campaign, part of the wider International Consortium for Atmospheric Research on Transport and Transformation (ICARTT). During the summer of 2004, eighteen flights comprising 160 h of measurements were conducted within a region bounded by 27 to 53°N and 36 to 139°W over an altitude range of 0.15 to 12 km. These large-scale surveys provided the opportunity to examine the characteristics of the atmospheric CO2 signal over sparsely sampled areas of North America and adjacent ocean basins. The observations showed a high degree of variability (≤18%) due to the myriad source and sink processes influencing the air masses intercepted over the INTEX-NA sampling domain. Surface fluxes had strong effects on continental scale concentration gradients. Clear signatures of CO2 uptake were seen east of the Mississippi River, notably a persistent CO2 deficit in the lowest 2-3 km. When combining the airborne CO2 measurements with LANDSAT and MODIS data products, the lowest CO2 mixing ratios observed during the campaign (337 ppm) were tied to mid-continental agricultural fields planted in corn and soybeans. We used simultaneous measurements of CO, O3, C2Cl4, C2H6, C2H2 and other unique chemical tracers to differentiate air mass types. Coupling these distinct air mass chemical signatures with transport history permitted identification of convection, stratosphere-troposphere exchange, long-range transport from Eastern Asia, boreal wildfires, and continental outflow as competing processes at multiple scales influencing the observed concentrations. Our results suggest these are important factors contributing to the large-scale distribution in CO2 mixing ratios thus these observations offer new constraints in the computation of the North American carbon budget.

  7. Discharge characteristics of a radio-frequency capacitively coupled Ar/O2 glow discharge at atmospheric pressure

    International Nuclear Information System (INIS)

    In this study, the discharge characteristics of the developed atmospheric pressure homogeneous and cold plasma source in Ar/O2 glow discharge driven by radio-frequency (13.56 MHz) are investigated experimentally by means of electric measurements. The electron density is estimated to be in the order of 1011 cm-3 in the abnormal discharge regime and is reduced by half in amount when the oxygen is mixed into argon plasma at oxygen-to-argon ratio of 0.3 and 0.6 vol.% at the same input power. The estimated electron temperature assumes the value of 1.4 eV in the abnormal discharge regime and the addition of oxygen to the argon plasma at the oxygen-to-argon ratio smaller than 1.0 vol.% does not alter the electron temperature appreciably.

  8. Effect of calf feeding regimes and diet EDTA on physico-chemical characteristics of veal stored under modified atmospheres.

    Science.gov (United States)

    Gariépy, C; Delaquis, P J; Pommier, S; De Passillé, A M; Fortin, J; Lapierre, H

    1998-05-01

    Physico-chemical characteristics of veal from 30 calves allotted to five different rations with respect to iron bioavailability were evaluated at packaging and after 2 and 4 weeks of storage under both 100% CO(2) and 100% N(2). The five diets were 'Milk', 'Grain', 'Mix' (combination of Milk and Grain) and 'Mix + EDTA' and 'Grain + EDTA' where 15 mg EDTA were added per mg Fe in the feed concentrate. Diet EDTA was generally more influential on veal quality than storage treatments. The chelator caused an unexpected pH drop in veal stored four weeks irrespective of storage conditions (p ≤ 0.05). However, the colour, texture and flavour of meat from animals fed EDTA in the Grain- and Mix-ration was equivalent to that of Milk-fed veal (p ≤ 0.05). The EDTA treatments also improved the appearance of veal under anoxic atmospheres. Upon storage however, the chelator increased veal drip losses (p ≤ 0.05) and also cooking losses from Grain-fed calves (p ≤ 0.05). Packaging under CO(2) decreased pH (p ≤ 0.05) and increased drip losses (p ≤ 0.05) but did not alter other physico-chemical parameters. Dietary treatments had no effect on shear forces (p > 0.05) which decreased after two weeks in storage (p ≤ 0.05) independent of gas atmospheres. Overall, the quality characteristics of pale veal were obtained following addition of EDTA in Grain- and Mix-fed animals and were maintained in storage. This approach looks promising for the veal industry but warrants further research. PMID:22063188

  9. Chemical characteristics and source of size-fractionated atmospheric particle in haze episode in Beijing

    Science.gov (United States)

    Tan, Jihua; Duan, Jingchun; Zhen, Naijia; He, Kebin; Hao, Jiming

    2016-01-01

    The abundance, behavior, and source of chemical species in size-fractionated atmospheric particle were studied with a 13-stage low pressure impactor (ELPI) during high polluted winter episode in Beijing. Thirty three elements (Al, Ca, Fe, K, Mg, Na, Si, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Sr, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, and Pb) and eight water soluble ions (Cl-, NO3-, SO42 -, NH4+, Na+, K+, Ca2 +, and Mg2 +) were determined by ICP/MS and IC, respectively. The size distribution of TC (OC + EC) was reconstructed. Averagely, 51.5 ± 5.3% and 74.1 ± 3.7% of the total aerosol mass was distributed in the sub-micron (PM1) and fine particle (PM2.5), respectively. A significant shift to larger fractions during heavy pollution episode was observed for aerosol mass, NH4+, SO42 -, NO3-, K, Fe, Cu, Zn, Cd, and Pb. The mass size distributions of NH4+, SO42 -, NO3-, and K were dominated by accumulation mode. Size distributions of elements were classified into four main types: (I) elements were enriched within the accumulation mode (fine, intermediate, and coarse modes; and (IV) those which were mainly found within particles larger than 2.7 μm (Al, Mg, Si, Ca, Sc, Tl, Fe, Sr, Zr, and Ba). [H+]cor showed an accumulation mode at 600-700 nm and the role of Ca2 + should be fully considered in the estimation of acidity. The acidity in accumulation mode particles suggested that generally gaseous NH3 was not enough to neutralize sulfate completely. PMF method was applied for source apportionment of elements combined with water soluble ions. Dust, vehicle, aged coal combustion, and sea salt were identified, and the size resolved source apportionments were discussed. Aged coal combustion was the important source of fine particles and dust contributed most to coarse particle.

  10. Characteristics and composition of atmospheric aerosols in Phimai, central Thailand during BASE-ASIA

    Science.gov (United States)

    Li, Can; Tsay, Si-Chee; Hsu, N. Christina; Kim, Jin Young; Howell, Steven G.; Huebert, Barry J.; Ji, Qiang; Jeong, Myeong-Jae; Wang, Sheng-Hsiang; Hansell, Richard A.; Bell, Shaun W.

    2013-10-01

    Comprehensive measurements of atmospheric aerosols were made in Phimai, central Thailand (15.183°N, 102.565°E, elevation: 206 m) during the BASE-ASIA field experiment from late February to early May in 2006. The observed aerosol loading was sizable for this rural site (mean aerosol scattering: 108 ± 64 Mm-1; absorption: 15 ± 8 Mm-1; PM10 concentration: 33 ± 17 μg m-3), and dominated by submicron particles. Major aerosol compounds included carbonaceous (OC: 9.5 ± 3.6 μg m-3; EC: 2.0 ± 2.3 μg m-3) and secondary species (SO42-: 6.4 ± 3.7 μg m-3, NH4+: 2.2 ± 1.3 μg m-3). While the site was seldom under the direct influence of large forest fires to its north, agricultural fires were ubiquitous during the experiment, as suggested by the substantial concentration of K+ (0.56 ± 0.33 μg m-3). Besides biomass burning, aerosols in Phimai during the experiment were also strongly influenced by industrial and vehicular emissions from the Bangkok metropolitan region and long-range transport from southern China. High humidity played an important role in determining the aerosol composition and properties in the region. Sulfate was primarily formed via aqueous phase reactions, and hygroscopic growth could enhance the aerosol light scattering by up to 60%, at the typical morning RH level of 85%. The aerosol single scattering albedo demonstrated distinct diurnal variation, ranging from 0.86 ± 0.04 in the evening to 0.92 ± 0.02 in the morning. This experiment marks the first time such comprehensive characterization of aerosols was made for rural central Thailand. Our results indicate that aerosol pollution has developed into a regional problem for northern Indochina, and may become more severe as the region's population and economy continue to grow.

  11. Characteristics of Nano Particles in the Atmosphere of Gyeongju National Park Area Using a Proton Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. W.; Hur, H. J.; Choi, J. H.; Kim, H. S. [Gyeongju Univ., Gyeongju (Korea, Republic of)

    2007-04-15

    The physico-chemical characteristics of the categorized aerosol with soil-related mineral species, anthropogenic-related heavy metal species, and aerosol-acidity-related element were analyzed based on the air-mass pathways. The lowest value of 0.6 {+-} 0.1 g m-3 was observed during the intensive fall period of 2005. The mass concentration of sulfur (S) was the highest in the intensive spring period and the lowest in the intensive summer period. The frequencies of the EM, the WC, the SC, and the NC events were 6, 17, 3, and 7, respectively. The continental air-mass-pathway categories were calculated consisting of 85% of the total 40 events whereas the marine air-mass-pathway categories were of 15%. The nanoparticles observed at the national park area of Gyeongju were estimated to be affected by soil-related elements when the air mass came from the western area of the Asian continent and to be predominantly affected by anthropogenic-related elements when air mass came from the northern area of the Asian continent through Korean peninsula. Soil-related elements were mainly observed in particles with sizes greater than 560 nm. The average mass fraction of anthropogenic-related elements was relatively much higher in the particle size range less than 320 nm.

  12. HCl in rocket exhaust clouds - Atmospheric dispersion, acid aerosol characteristics, and acid rain deposition

    Science.gov (United States)

    Pellett, G. L.; Sebacher, D. I.; Bendura, R. J.; Wornom, D. E.

    1983-01-01

    Both measurements and model calculations of the temporal dispersion of peak HCl (g + aq) concentration in Titan III exhaust clouds are found to be well characterized by one-term power-law decay expressions. The respective coefficients and decay exponents, however, are found to vary widely with meteorology. The HCl (g), HCl (g + aq), dewpoint, and temperature-pressure-altitude data for Titan III exhaust clouds are consistent with accurately calculated HCl/H2O vapor-liquid compositions for a model quasi-equilibrated flat surface aqueous aerosol. Some cloud evolution characteristics are also defined. Rapid and extensive condensation of aqueous acid clearly occurs during the first three min of cloud rise. Condensation is found to be intensified by the initial entrainment of relatively moist ambient air from lower levels, that is, from levels below eventual cloud stabilization. It is pointed out that if subsequent dilution air at stabilization altitude is significantly drier, a state of maximum condensation soon occurs, followed by an aerosol evaporation phase.

  13. Characteristics of atmospheric aerosol optical depth variation over China in recent 30 years

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This note retrieves the annual and monthly mean 0.75 μm aerosol optical depth (AOD) by using the daily direct solar radiation and sunshine duration data of 47 solar stations from 1961 to 1990. The characteristic of AOD variation over China in recent 30 years was analyzed. The results indicate that AOD increased obviously over China from 1961 to 1990. AOD increased most rapidly over the east part of Southwest China, the middle-and-lower reaches of the Yangtze River and the Tibetan Plateau. The increasing trend of AOD is also relatively distinct in North China, the Shandong Peninsula, east part of Qinghai Province, and coastal areas of Guangdong Province. However, in most parts of Northwest China and Northeast China, the increase of AOD is less significant, while in the west part of the Xinjiang Uygur Autonomous Region and some parts of Yunnan Province, AOD shows decreasing tendency. Generally, AOD reaches its maximum in spring and the minimum appears in summer. As to the linear trend, the maximum occurs in spring but the minimum in winter. Among the 47 stations selected in this note, the largest three stations of AOD are Chengdu, Chongqing and Nanchong, respectively, which all lie in the Sichuan Basin, and the smallest value of AOD occurs in Jinghong located in Yunnan Province.

  14. Atmospheric boundary layer characteristics over the Pearl River Delta, China during summer 2006: measurement and model results

    Directory of Open Access Journals (Sweden)

    S. J. Fan

    2011-02-01

    Full Text Available Atmospheric conditions are often connected with the occurrence of high pollution episodes especially in urban areas. As part of the PRIDE-PRD2006 intensive campaign, atmospheric boundary layer (ABL measurements were carried out at Qingyuan, Panyu and Xinken in the Pearl River Delta (PRD from 1 July to 30 July of 2006. It was found that in summer, the surface winds in PRD are more controlled by the south, and there usually is vertical wind shear at the height of 800 m or so, therefore, PRD is often influenced by the tropical cyclone/typhoon. The subsidence and precipitation from a tropical cyclone will affect the air quality of PRD. Under the subsidence, the wind speed in ABL and the height of ABL will decrease and result in high level concentrations. When the background wind speed is small or calm, the wind profile at Panyu and Xinken change dramatically with height, which is perhaps caused by the local circulations, such as the sea land breeze. For more understanding about the ABL of PRD, the simulations by the WRF mesoscale model were used to analyse the ABL characteristics in PRD. From three kinds of weather condition simulations (subsidence days, rainy days and sunny days by WRF model, it was found that the simulated temperature, wind fields in these three cases were moderately consistent with the measurements. The results show that the diurnal variation of ABL in subsidence days and sunny days are obvious, but the diurnal variation of ABL on rainy days is not obvious. The ABL is obviously affected by the local circulation and the features of ABL are different in various stations. A simulation focus on high pollution episode during the subsidence days from 12–15 July 2006, occurred under high pressure conditions, accompanied by a tropical cyclone "Bilis". Comparing the simulated vertical wind fields and temperature structure with the ABL measurements at Xinken, Panyu and Qingyuan station, it was found that, the modelled and measured

  15. Oxidation characteristics of nickel-base superalloys at high temperature in air and helium atmospheres

    International Nuclear Information System (INIS)

    Nickel-base superalloys are considered as materials for piping and structural materials in a very high temperature gas cooled reactor (VHTR). They are subjected to the environmental degradation caused by a continuous process for oxidation due to small amount of impurities in He coolant during long term operation. In the present study, the oxidation behaviors of several nickel-base superalloys such as Alloy-617, Haynes-214 and Haynes-230 in particular, were studied at the temperature of 900 and 1100 C degrees in air, and in the high purity He environment. Oxide layers were analyzed by SEM (Scanning Electron Microscope) and EDX (Energy Dispersive X-ray analysis). The differences in oxidation behaviors of these alloys were mainly caused by different protective oxide layers on surface. In the case of Alloy-617 and Haynes-230, Cr2O3 layer formed on the surface which is not stable at 1100 C degrees. Therefore, the weight increased significantly due to oxidation at the initial stage, which followed by a decrease due to the scaling and volatilization of Cr2O3 layer. On the other hand, since Haynes-214 has mainly Al2O3 oxide layer on surface which is more stable and has more dense structure at higher temperature, the weight gain eventually reaches to parabolic. Microstructural characteristics of internal carbides and carbide depletion zone were analyzed. With oxidation time, continuous grain boundary carbides of M23C6 type were getting thin or it disappeared partially. Especially, carbides on grain boundary disappeared entirely below oxide layer (carbide depletion zone). It was getting wide with oxidation time. For Haynes-214, the size of carbide depletion zone was smaller than other alloys because Al2O3 layer acted as a diffusion layer prevented effectively the penetration of oxygen into base metal. (authors)

  16. Influence of the characteristics of atmospheric boundary layer on the vertical distribution of air pollutant in China's Yangtze River Delta

    Science.gov (United States)

    Wang, Chenggang; Cao, Le

    2016-04-01

    Air pollution occurring in the atmospheric boundary layer is a kind of weather phenomenon which decreases the visibility of the atmosphere and results in poor air quality. Recently, the occurrence of the heavy air pollution events has become more frequent all over Asia, especially in Mid-Eastern China. In December 2015, the most severe air pollution in recorded history of China occurred in the regions of Yangtze River Delta and Beijing-Tianjin-Hebei. More than 10 days of severe air pollution (Air Quality Index, AQI>200) appeared in many large cities of China such as Beijing, Tianjin, Shijiazhuang and Baoding. Thus, the research and the management of the air pollution has attracted most attentions in China. In order to investigate the formation, development and dissipation of the air pollutions in China, a field campaign has been conducted between January 1, 2015 and January 28, 2015 in Yangtze River Delta of China, aiming at a intensive observation of the vertical structure of the air pollutants in the atmospheric boundary layer during the time period with heavy pollution. In this study, the observation data obtained in the field campaign mentioned above is analyzed. The characteristics of the atmospheric boundary layer and the vertical distribution of air pollutants in the city Dongshan located in the center of Lake Taihu are shown and discussed in great detail. It is indicated that the stability of the boundary layer is the strongest during the nighttime and the early morning of Dongshan. Meanwhile, the major air pollutants, PM2.5 and PM10 in the boundary layer, reach their maximum values, 177.1μg m-3 and 285μg m-3 respectively. The convective boundary layer height in the observations ranges from approximately 700m to 1100m. It is found that the major air pollutants tend to be confined in a relatively shallow boundary layer, which represents that the boundary layer height is the dominant factor for controlling the vertical distribution of the air pollutants. In

  17. Channel rays and ionization at high temperatures

    International Nuclear Information System (INIS)

    The book includes the following chapters: (1) Channel rays: development of channel rays and its observation by light effects; heat effects; chemical effects; ionization; sputtering; observation of the electricity transported by the channel rays radiation, secondary radiation; photoelectric channel rays; magnetic end electric deflection of channel rays; charge exchange of channel rays; theory of the charge reversal; dependence of the charge reversal on the static gas; absorption and scattering of channel rays; theory on the origin of channel rays; light emission of channel rays; subdivision in Doppler stripes; absolute value of the light emission by channel rays; glow excitation; dependence of the light emission from velocity; electrical and magnetic effects on the light emission by channel rays; polarization of the light emitted by channel rays; positive rays at the anode; electric and electrodynamic effects on the spectral lines. (2) Electric arc: the characteristics of the DC arc; influence of the surrounding atmosphere pressure; arc stability; anode and cathode drop; temperature dependence in the arc characteristics; ionic theory of the arc; transport of matter in the arc; electromotive forces in the arc; characteristics of AC arcs; alternating current between dissimilar electrodes; the vibrating arc; critics of the Simon theory; magnetic influence on the arc; traveling arcs; magnetic rotation; temperature determination in the arc; radiation of the arc; chemical processes in the arc. (3) Glow electrodes: characterization of the phenomenon; negative ion emission from hot bodies; the kinetic energy of emitted electrons, theoretical considerations; by metals caused positive ionization; ionization by hot salts. (4) Flame conduction: electrical characterization of the flame; electric currents in flames; theory of flame conduction; determination of the traveling velocity in the flame; influence of magnetic fields; ion formation in the pure flame and in the salt flame

  18. Effect of Modified Atmosphere Packaging and Vacuum Packaging on Quality Characteristics of Low Grade Beef during Cold Storage

    Science.gov (United States)

    Hur, S. J.; Jin, S. K.; Park, J. H.; Jung, S. W.; Lyu, H. J.

    2013-01-01

    Many studies have been carried out with respect to packaging methods and temperature conditions of beef. However, the effects of packaging methods and temperature conditions on the quality characteristics have not been extensively studied in low-grade beef. Low-grade beef samples were divided into 3 groups (C: ziplock bag packaging, T1: vacuum packaging, and T2: modified atmosphere packaging (MAP), CO2/N2 = 3:7) and samples were stored at 4°C for 21 days. The water-holding capacity (WHC) was significantly lower in T1 than in the other samples up to 14 days of storage. The thiobarbituric acid reactive substances and volatile basic nitrogen values were significantly lower in T1 and T2 than in C after 7 to 14 days of storage. The total bacterial counts were significantly lower in T1 and T2 than in C after 14 days of storage. In a sensory evaluation, tenderness and overall acceptability were significantly higher in T1 and T2 than in C at the end of the storage period (21 days). We propose that the MAP method can improve beef quality characteristics of low-grade beef during cold storage. However, the beneficial effects did not outweigh the cost increase to implement MAP. PMID:25049769

  19. Effect of gamma-irradiation on instrumental colour and textural characteristics of tomato stored under modified atmosphere packaging

    International Nuclear Information System (INIS)

    Changes in quality characteristics of tomato (Lycopersicum esculentum Mill) as influenced by modified atmosphere packaging (MAP) and γ-irradiation 0, 1, 2, 3 and 4 KGy doses and low temperature (LT, 12± 1 deg C) storage at 90-95% RH were studied. Tomatoes packed with LDPE film could be stored up to 21 days at 12±1 deg C and 90-95% RH with the maximum retention of fruit quality characteristics such as 1.92 a/b ratio, 46.6 N shear value and 16.4 N penetration value as compared to 1.88 a/b ratio, 41.3 N shear value and 13.1 N penetration value in untreated open kept control tomatoes stored for 7 days under same conditions. Irradiation in combination with MAP and LT storage were not suitable for tomatoes harvested at breaker stage of maturity for shelf-life extension and maintenance of fruit quality. (author)

  20. Influence of pulsed nanosecond volume discharge in atmospheric-pressure air on the electrical characteristics of MCT epitaxial films

    Science.gov (United States)

    Grigoryev, Denis V.; Voitsekhovskii, Alexandr V.; Lozovoy, Kirill A.; Nesmelov, Sergey N.; Dzyadukh, Stanislav M.; Tarasenko, Viktor F.; Shulepov, Michail A.; Dvoretskii, Sergei A.

    2015-12-01

    The purpose of this paper was investigating the effect of volume nanosecond discharge in air at atmospheric pressure on the electro-physical properties of the HgCdTe (MCT) epitaxial films grown by molecular beam epitaxy. Hall measurements of electro-physical parameters of MCT samples after irradiation have shown that there is a layer of epitaxial films exhibiting n-type conductivity that is formed in the near-surface area. After more than 600 pulses of influence parameters and thickness of the resulting n-layer is such that the measured field dependence of Hall coefficient corresponds to the material of n-type conductivity. Also it is shown that the impact of the discharge leads to significant changes in electro-physical characteristics of MIS structures. This fact is demonstrated by increase in density of positive fixed charge, change in the hysteresis type of the capacitance-voltage characteristic, an increase in density of surface states. The preliminary results show that it is possible to use such actions in the development of technologies of the controlled change in the properties of MCT.

  1. Mean Climatic Characteristics in High Northern Latitudes in an Ocean-Sea Ice-Atmosphere Coupled Model

    Institute of Scientific and Technical Information of China (English)

    刘喜迎; 张学洪; 俞永强; 宇如聪

    2004-01-01

    Emphasizing the model's ability in mean climate reproduction in high northern latitudes, results from an ocean-sea ice-atmosphere coupled model are analyzed. It is shown that the coupled model can simulate the main characteristics of annual mean global sea surface temperature and sea level pressure well, but the extent of ice coverage produced in the Southern Hemisphere is not large enough. The main distribution characteristics of simulated sea level pressure and temperature at 850 hPa in high northern latitudes agree well with their counterparts in the NCEP reanalysis dataset, and the model can reproduce the Arctic Oscillation (AO) mode successfully. The simulated seasonal variation of sea ice in the Northern Hemisphere is rational and its main distribution features in winter agree well with those from observations.But the ice concentration in the sea ice edge area close to the Eurasian continent in the inner Arctic Ocean is much larger than the observation. There are significant interannual variation signals in the simulated sea ice concentration in winter in high northern latitudes and the most significant area lies in the Greenland Sea, followed by the Barents Sea. All of these features agree well with the results from observations.

  2. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    Directory of Open Access Journals (Sweden)

    A. Petzold

    2008-05-01

    Full Text Available Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transformation studies in the plume of a large container ship in the English Channel using the DLR aircraft Falcon 20 E-5. Observations from emission studies and plume studies combined with a Gaussian plume dispersion model yield a consistent picture of particle transformation processes from emission to atmospheric processing during plume expansion. Particulate matter emission indices obtained from plume measurements are 8.8±1.0×1015(kg fuel−1 by number for non-volatile particles and 174±43 mg (kg fuel−1 by mass for Black Carbon (BC. Values determined for test rig conditions between 85 and 110% engine load are of similar magnitude. For the total particle number including volatile compounds no emission index can be derived since the volatile aerosol fraction is subject to rapid transformation processes in the plume. Ship exhaust particles occur in the size range Dp<0.3 μm, showing a bi-modal structure. The combustion particle mode is centred at modal diameters of 0.05 μm for raw emissions to 0.10 μm at a plume age of 1 h. The smaller-sized volatile particle mode is centred at Dp≤0.02 μm. From the decay of ship exhaust particle number concentrations in an expanding plume, a maximum plume life time of approx. 24 h is estimated for a well-mixed marine boundary layer.

  3. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    Directory of Open Access Journals (Sweden)

    A. Petzold

    2007-10-01

    Full Text Available Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B{&}W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transformation studies in the plume of a large container ship in the English Channel using the DLR aircraft Falcon 20 E-5. Observations from emission studies and plume studies combined with a Gaussian plume dispersion model yield a consistent picture of particle transformation processes from emission to atmospheric processing during plume expansion. Particulate matter emission indices obtained from plume measurements are 8.8±1.0×1015(kg fuel−1 by number for non-volatile particles and 174±43 mg (kg fuel−1 by mass for Black Carbon (BC. Values determined for test rig conditions between 85 and 110% engine load are of similar magnitude. For the total particle number including volatile compounds no emission index can be derived since the volatile aerosol fraction is subject to rapid transformation processes in the plume. Ship exhaust particles occur in the size range Dp<0.3 μm, showing a bi-modal structure. The combustion particle mode is centred at modal diameters of 0.05 μm for raw emissions to 0.10 μm at a plume age of 1 h. The smaller-sized volatile particle mode is centred at Dp≤0.02 μm. From the decay of ship exhaust particle number concentrations in an expanding plume, a maximum plume life time of approx. 24 h is estimated for a well-mixed marine boundary layer.

  4. Temperature-dependent characteristics of AlGaN/GaN FinFETs with sidewall MOS channel

    Science.gov (United States)

    Im, Ki-Sik; Kang, Hee-Sung; Kim, Do-Kywn; Vodapally, Sindhuri; Park, YoHan; Lee, Jae-Hoon; Kim, Yong-Tae; Cristoloveanu, Sorin; Lee, Jung-Hee

    2016-06-01

    AlGaN/GaN fin-shaped field-effect transistors (FinFETs) with variable fin width have been fabricated and characterized. Low-temperature measurements reveal distinct operation modes for wide FinFET, narrow FinFET and planar FET. The wide fin device exhibits broad transconductance (gm) that decreases sublinearly with increasing temperature due to the existence of the sidewall metal-oxide-semiconductor (MOS) channel. By comparison, the conventional planar AlGaN/GaN metal-insulator-semiconductor heterostructure FET (MISHFET) features relatively narrow gm curve and near-exponentially decay of gm with temperature. The effect of the sidewall channel becomes more prominent for the narrow fin device and leads to two distinct gm peaks. The first peak at negative gate voltage corresponds to the two-dimensional electron gas (2-DEG) channel, while the second peak at positive gate voltage is related to the sidewall MOS channel. Measurements also show that the electrons in 2-DEG channel experience polar-optical-phonon scattering unlike the electrons in the sidewall MOS channel which are mainly subject to Coulomb scattering.

  5. Characteristics of water-vapour inversions observed over the Arctic by Atmospheric Infrared Sounder (AIRS and radiosondes

    Directory of Open Access Journals (Sweden)

    A. Devasthale

    2011-05-01

    Full Text Available An accurate characterization of the vertical structure of the Arctic atmosphere is useful in climate change and attribution studies as well as for the climate modelling community to improve projections of future climate over this highly sensitive region. Here, we investigate one of the dominant features of the vertical structure of the Arctic atmosphere, i.e. water-vapour inversions, using eight years of Atmospheric Infrared Sounder data (2002–2010 and radiosounding profiles released from the two Arctic locations (North Slope of Alaska at Barrow and during SHEBA. We quantify the characteristics of clear-sky water vapour inversions in terms of their frequency of occurrence, strength and height covering the entire Arctic for the first time.

    We found that the frequency of occurrence of water-vapour inversions is highest during winter and lowest during summer. The inversion strength is, however, higher during summer. The observed peaks in the median inversion-layer heights are higher during the winter half of the year, at around 850 hPa over most of the Arctic Ocean, Siberia and the Canadian Archipelago, while being around 925 hPa during most of the summer half of the year over the Arctic Ocean. The radiosounding profiles agree with the frequency, location and strength of water-vapour inversions in the Pacific sector of the Arctic. In addition, the radiosoundings indicate that multiple inversions are the norm with relatively few cases without inversions. The amount of precipitable water within the water-vapour inversion structures is estimated and we find a distinct, two-mode contribution to the total column precipitable water. These results suggest that water-vapour inversions are a significant source to the column thermodynamics, especially during the colder winter and spring seasons. We argue that these inversions are a robust metric to test the reproducibility of thermodynamics within climate models. An accurate statistical

  6. Atmospheric boundary layer characteristics over the Pearl River Delta, China, during the summer of 2006: measurement and model results

    Directory of Open Access Journals (Sweden)

    S. J. Fan

    2011-07-01

    Full Text Available As part of the PRIDE-PRD2006 intensive campaign, atmospheric boundary layer (ABL measurements were performed in Qingyuan, Panyu, and Xinken over the Pearl River Delta (PRD on 1–30 July 2006. During the summer, the surface winds over the PRD are generally controlled by the south, usually with vertical wind shear at a height of approximately 800 m. Subsidence and precipitation from a tropical cyclone affects the air quality of the PRD. Under subsidence, wind speed in the ABL and the height of the ABL decrease and result in high-level concentrations. When the background wind speed is small or calm, the wind profile in Panyu and Xinken changes dramatically with height, which is perhaps caused by local circulation, such as sea-land breezes. To better understand the ABL of the PRD, simulations that used the Weather Research and Forecasting (WRF mesoscale model were utilized to analyze the ABL characteristics over the PRD. Based on three types of weather condition simulations (i.e., subsidence days, rainy days, and sunny days, the WRF model revealed that the simulated temperature and wind fields in these three cases were moderately consistent with the measurements. The results showed that diurnal variations of the ABL height on subsidence days and sunny days were obvious, but diurnal variations of the ABL height on rainy days were not apparent. The ABL is obviously affected by local circulation, and the ABL features are different at various stations. A simulation focused on a high pollution episode during the subsidence days on 12–15 July 2006, occurred under high-pressure conditions, accompanied by the tropical cyclone "Bilis". A comparison of the simulated vertical wind fields and temperature structure with the ABL measurements at Xinken, Panyu, and Qingyuan stations found that the modeled and measured atmospheric fields revealed two different types of ABL characteristics over the PRD. When the surface winds over the PRD were light or nearly calm

  7. Performance Characteristics of a PEM Fuel Cell with Parallel Flow Channels at Different Cathode Relative Humidity Levels

    Directory of Open Access Journals (Sweden)

    Sang Soon Hwang

    2009-11-01

    Full Text Available In fuel cells flow configuration and operating conditions such as cell temperature, humidity at each electrode and stoichiometric number are very crucial for improving performance. Too many flow channels could enhance the performance but result in high parasite loss. Therefore a trade-off between pressure drop and efficiency of a fuel cell should be considered for optimum design. This work focused on numerical simulation of the effects of operating conditions, especially cathode humidity, with simple micro parallel flow channels. It is known that the humidity at the cathode flow channel becomes very important for enhancing the ion conductivity of polymer membrane because fully humidified condition was normally set at anode. To investigate the effect of humidity on the performance of a fuel cell, in this study humidification was set to 100% at the anode flow channel and was changed by 0–100% at the cathode flow channel. Results showed that the maximum power density could be obtained under 60% humidified condition at the cathode where oxygen concentration was moderately high while maintaining high ion conductivity at a membrane.

  8. Pressure drop characteristics on gas/liquid two-phase flow in a curved micro-channel affected by the wall wettability

    International Nuclear Information System (INIS)

    A gas/liquid two-phase flow in a curved micro-channel is encountered in many application such as nuclear engineering, mechanical engineering, environmental engineering. In the present investigation, detailed observations on the flow patterns and measurements for pressure drop characteristics affected by the wall wettability were carried out. The test channel has square cross section that has 2.0 mm on a side, and the radii of the curvature were 1.0 mm and 3.0 mm. The superficial velocity of the gas and liquid are ranged from 0.083 m/s to 15.9 m/s for gas-phase, and 0.042 m/s to 1.67 m/s for liquid-phase, respectively. We could see the specific phenomena, the staying of bubbles and the changing of flow pattern near the exit of the curved part in the curvature radius 1.0 mm. Such as a polymer electrolyte fuel cell, there are curved micro-channels with the water repellent channel in practical use. So, in order to investigate the influence of the wall wettability, we applied the water repellent micro-channel. In the case of the water repellent micro-channel, we could see a new flow pattern of the rivulet flow. The pressure drop measurements were also carried out, we correlated the relation of the Lochhalt-Martinelli's parameter and the pressure fluctuation intensity. The pressure fluctuation became maximum value in the case of the slug-annular flow. (author)

  9. Characteristics of four-channel Cherenkov-type detector for measurements of runaway electrons in the ISTTOK tokamak

    International Nuclear Information System (INIS)

    A diagnostics capable of characterizing the runaway and superthermal electrons has been developing on the ISTTOK tokamak. In previous paper, a use of single-channel Cherenkov-type detector with titanium filter for runaway electron studies in ISTTOK was reported. To measure fast electron populations with different energies, a prototype of a four-channel detector with molybdenum filters was designed. Test-stand studies of filters with different thicknesses (1, 3, 7, 10, 20, 50, and 100 μm) have shown that they should allow the detection of electrons with energies higher than 69, 75, 87, 95, 120, 181, and 260 keV, respectively. First results of measurements with the four-channel detector revealed the possibility to measure reliably different fast electrons populations simultaneously.

  10. Assessment of wind characteristics and atmospheric dispersion modeling of 137Cs on the Barakah NPP area in the USA

    International Nuclear Information System (INIS)

    This paper presents the results of an analysis of wind characteristics and atmosphere dispersion modeling that are based on computational simulation and part of a preliminary study evaluating environmental radiation monitoring system (ERMS) positions within the Barakah nuclear power plant (BNPP). The return period of extreme wind speed was estimated using the Weibull distribution over the life time of the BNPP. In the annual meteorological modeling, the winds from the north and west accounted for more than 90 % of the wind directions. Seasonal effects were not represented. However, a discrepancy in the tendency between daytime and nighttime was observed. Six variations of cesium-137 (137Cs) dispersion test were simulated under severe accident condition. The 137Cs dispersion was strongly influenced by the direction and speed of the main wind. A virtual receptor was set and calculated for observation of the 137Cs movement and accumulation. The results of the surface roughness effect demonstrated that the deposition of 137Cs was affected by surface condition. The results of these studies offer useful information for developing environmental radiation monitoring systems (ERMSs) for the BNPP and can be used to assess the environmental effects of new nuclear power plant.

  11. Assessment of wind characteristics and atmospheric dispersion modeling of {sup 137}Cs on the Barakah NPP area in the USA

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Kuk; Lee, Kun Jai; Yun, Jong IL [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Jae Chul; Belorid, Miloslav [Institute of Environmental Research, Chuncheon (Korea, Republic of); Beeley, Philip A. [Khalifa University of Science, Technology and Research, Dubai (Antigua and Barbuda)

    2014-08-15

    This paper presents the results of an analysis of wind characteristics and atmosphere dispersion modeling that are based on computational simulation and part of a preliminary study evaluating environmental radiation monitoring system (ERMS) positions within the Barakah nuclear power plant (BNPP). The return period of extreme wind speed was estimated using the Weibull distribution over the life time of the BNPP. In the annual meteorological modeling, the winds from the north and west accounted for more than 90 % of the wind directions. Seasonal effects were not represented. However, a discrepancy in the tendency between daytime and nighttime was observed. Six variations of cesium-137 ({sup 137}Cs) dispersion test were simulated under severe accident condition. The {sup 137}Cs dispersion was strongly influenced by the direction and speed of the main wind. A virtual receptor was set and calculated for observation of the {sup 137}Cs movement and accumulation. The results of the surface roughness effect demonstrated that the deposition of {sup 137}Cs was affected by surface condition. The results of these studies offer useful information for developing environmental radiation monitoring systems (ERMSs) for the BNPP and can be used to assess the environmental effects of new nuclear power plant.

  12. Global atmospheric energy deposition by energetic electrons - Quantitative spatial and temporal characteristics inferred from the Atmospheric X-ray Imaging Spectrometer (PEM/AXIS) on UARS

    Science.gov (United States)

    Chenette, D. L.; Datlowe, D. W.; Robinson, R. M.; Schumaker, T. L.; Vondrak, R. R.; Frahm, R. A.; Sharber, J. R.; Winningham, J. D.

    1993-01-01

    The primary purpose of PEM/AXIS is to provide a global monitor of the energy input to the upper atmosphere due to energetic electrons. The design, development, and calibration of AXIS are described and an assessment of its excellent on-orbit performance is presented. The unique capabilities of X-ray imaging spectrometers to monitor the global patterns of electron energy deposition in the atmosphere are shown through an analysis of some specific cases during the first year of the UARS mission.

  13. 电力载波通信信道特性研究%Study on the Channel Characteristics of Power Carrier Communication

    Institute of Scientific and Technical Information of China (English)

    张高境

    2015-01-01

    Power line channel is a power line carrier communication in safe and reliable transmission of information carrier, so on the characteristic impedance, attenuation characteristics and noise characteristics analysis is the premise of power line carrier communication network construction. In the end, the integration of PLC and Wi-Fi is the trend of the future development.%电力线信道是电力载波通信中安全、可靠传输信息载体,因此关于阻抗特性、衰减特性、噪声特性方面的分析是电力载波通信网络构建的前提。最后提出了PLC与Wi-Fi等多种网络融合是未来发展的趋势。

  14. Impacts of Bolbophorus damnificus digenea: Bolbophoridae on production characteristics of channel catfish, Ictalurus punctatus, raised in experimental ponds

    Science.gov (United States)

    Bolbophorus damnificus was recognized as a threat to channel catfish, Ictalurus punctatus, production in Louisiana and Mississippi in 1997 and 1999, respectively. Severe to moderate outbreaks (=34% prevalence) are correlated to heavy losses, but impact of mild outbreaks with low prevalence (<33%) wa...

  15. Effect of channel wall conductance on the performance characteristics of self-cooled liquid metal fusion reactor blankets

    International Nuclear Information System (INIS)

    One of the critical issues in self-cooled liquid metal tritium breeding blankets in magnetically confined fusion reactors is strong MHD effects particularly when the channel walls are not electrically insulated from the flowing liquid metals. Another critical issue is the cooling of the first wall which is subjected to intense heat load from the fusion plasma. In this work we investigate the effect of channel wall conductance on the friction factor and Nusselt number. It is shown by solving the indication and linear momentum equations that even for relatively small channel wall conductance ratios, the friction factor increases by an order of magnitude for the typical Hartmann numbers encountered in fusion reactor blankets. Furthermore, by solving the temperature equation, it is shown that channel wall conductance has negligible effect on Nusselt number in spite of high velocity jets developing near the side walls. Taking into account these limitations, it is shown however, that the self-cooled liquid metal blankets remain a feasible proposition for both first wall heat extraction and bulk heat removal from the blanket. The most important thermal-hydraulic performance parameter -the heat removal rate to pumping power ratio- can still be kept quite high by suitably choosing the design variables of the liquid metal cooling system. The results are presented and compared for the three prime candidates for self-cooled liquid metal breeding blankets, i.e., lithium, lead-lithium, and tin-lithium alloys. (author)

  16. Structural and functional characteristics of natural and constructed channels draining a reclaimed mountaintop removal and valley fill coal mine

    Science.gov (United States)

    Mountaintop removal and valley fill (MTR/VF) coal mining has altered the landscape of the Central Appalachian region in the United States. The goals of this study were to 1) compare the structure and function of natural and constructed stream channels in forested and MTR/VF catch...

  17. Channel Allocation Based on Content Characteristics for Video Transmission in Time-Domain-Based Multichannel Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Md. Jalil Piran

    2015-01-01

    Full Text Available This paper proposes a method for channel allocation based on video content requirements and the quality of the available channels in cognitive radio networks (CRNs. Our objective is to save network bandwidth and achieve high-quality video delivery. In this method, the content is divided into clusters based on scene complexity and PSNR. To allocate channel to the clusters over multichannel CRNs, we first need to identify the licensee’s activity and then maximize the opportunistic usage accordingly. Therefore, we classify short and long time transmission opportunities based on the licensee’s activities using a Bayesian nonparametric inference model. Furthermore, to prevent transmission interruption, we consider the underlay mode for transmission of the clusters with a lower bitrate. Next, we map the available spectrum opportunities to the content clusters according to both the quality of the channels and the requirements of the clusters. Then, a distortion optimization model is constructed according to the network transmission mechanism. Finally, to maximize the average quality of the delivered video, an optimization problem is defined to determine the best bitrate for each cluster by maximizing the sum of the logarithms of the frame rates. Our extensive simulation results prove the superior performance of the proposed method in terms of spectrum efficiency and the quality of delivered video.

  18. Atom-Rydberg-atom chemi-ionization processes in solar and DB white-dwarf atmospheres in the presence of (n - n')-mixing channels

    Science.gov (United States)

    Mihajlov, A. A.; Srećković, V. A.; Ignjatović, Lj. M.; Dimitrijević, M. S.

    2016-05-01

    In this paper, the rate coefficients of the chemi-ionization processes in H(1s) + H*(n, l) and He(1s2) + He*(n, l) collisions (where the principal quantum number n ≫ 1) are determined for the first time, taking into account the influence of the corresponding (n - n')-mixing processes. It is demonstrated that the inclusion of (n - n') mixing in the calculation influences the values of chemi-ionization rate coefficients significantly, particularly in the lower part of the block of Rydberg states. The interpretation of this influence is based on two existing methods of describing inelastic processes in symmetrical atom-Rydberg-atom collisions. The calculations of the chemi-ionization rate coefficients are performed for the temperature region that is characteristic of solar and DB white-dwarf atmospheres.

  19. Structural characteristics of hydrated protons in the conductive channels: effects of confinement and fluorination studied by molecular dynamics simulation.

    Science.gov (United States)

    Zhang, Ning; Song, Yuechun; Ruan, Xuehua; Yan, Xiaoming; Liu, Zhao; Shen, Zhuanglin; Wu, Xuemei; He, Gaohong

    2016-09-21

    The relationship between the proton conductive channel and the hydrated proton structure is of significant importance for understanding the deformed hydrogen bonding network of the confined protons which matches the nanochannel. In general, the structure of hydrated protons in the nanochannel of the proton exchange membrane is affected by several factors. To investigate the independent effect of each factor, it is necessary to eliminate the interference of other factors. In this paper, a one-dimensional carbon nanotube decorated with fluorine was built to investigate the independent effects of nanoscale confinement and fluorination on the structural properties of hydrated protons in the nanochannel using classical molecular dynamics simulation. In order to characterize the structure of hydrated protons confined in the channel, the hydrogen bonding interaction between water and the hydrated protons has been studied according to suitable hydrogen bond criteria. The hydrogen bond criteria were proposed based on the radial distribution function, angle distribution and pair-potential energy distribution. It was found that fluorination leads to an ordered hydrogen bonding structure of the hydrated protons near the channel surface, and confinement weakens the formation of the bifurcated hydrogen bonds in the radial direction. Besides, fluorination lowers the free energy barrier of hydronium along the nanochannel, but slightly increases the barrier for water. This leads to disintegration of the sequential hydrogen bond network in the fluorinated CNTs with small size. In the fluorinated CNTs with large diameter, the lower degree of confinement produces a spiral-like sequential hydrogen bond network with few bifurcated hydrogen bonds in the central region. This structure might promote unidirectional proton transfer along the channel without random movement. This study provides the cooperative effect of confinement dimension and fluorination on the structure and hydrogen

  20. Influences of oxygen content on characteristics of atmospheric pressure dielectric barrier discharge in argon/oxygen mixtures

    Science.gov (United States)

    Fang, Zhi; Shao, Tao; Wang, Ruixue; Yang, Jing; Zhang, Cheng

    2016-04-01

    The dielectric barrier discharge generated in argon/oxygen mixtures at atmospheric pressure is investigated, and the effect of oxygen content on discharge characteristics at applied voltage of 4.5 kV is studied by means of electrical measurements and optical diagnostics. The results show that the filaments in the discharge regime become more densely packed with the increasing in the oxygen content, and the distribution of the filaments is more uniform in the gap. An increase in the oxygen content results in a decrease in the average power consumed and transported charges, while there exists an optimal value of oxygen content for the production of oxygen radicals. The maximal yield of oxygen radicals is obtained in mixtures of argon with 0.3% oxygen addition, and the oxygen radicals then decrease with the further increase in the oxygen content. The oxygen/argon plasma is employed to modify surface hydrophilicity of the PET films to estimate the influence of oxygen content on the surface treatment, and the static contact angles before and after the treatments are measured. The lowest contact angle is obtained at a 0.3% addition of oxygen to argon, which is in accordance with the optimum oxygen content for oxygen radicals generation. The electron density and electron temperature are estimated from the measured current and optical emission spectroscopy, respectively. The electron density is found to reduce significantly at a higher oxygen content due to the increased electron attachment, while the estimated electron temperature do not change apparently with the oxygen content. Contribution to the Topical Issue "Recent Breakthroughs in Microplasma Science and Technology", edited by Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu.

  1. Roles of land surface albedo and horizontal resolution on the Indian summer monsoon biases in a coupled ocean-atmosphere tropical-channel model

    Science.gov (United States)

    Samson, Guillaume; Masson, Sébastien; Durand, Fabien; Terray, Pascal; Berthet, Sarah; Jullien, Swen

    2016-05-01

    The Indian summer monsoon (ISM) simulated over the 1989-2009 period with a new 0.75° ocean-atmosphere coupled tropical-channel model extending from 45°S to 45°N is presented. The model biases are comparable to those commonly found in coupled global climate models (CGCMs): the Findlater jet is too weak, precipitations are underestimated over India while they are overestimated over the southwestern Indian Ocean, South-East Asia and the Maritime Continent. The ISM onset is delayed by several weeks, an error which is also very common in current CGCMs. We show that land surface temperature errors are a major source of the ISM low-level circulation and rainfall biases in our model: a cold bias over the Middle-East (ME) region weakens the Findlater jet while a warm bias over India strengthens the monsoon circulation over the southern Bay of Bengal. A surface radiative heat budget analysis reveals that the cold bias is due to an overestimated albedo in this desertic ME region. Two new simulations using a satellite-observed land albedo show a significant and robust improvement in terms of ISM circulation and precipitation. Furthermore, the ISM onset is shifted back by 1 month and becomes in phase with observations. Finally, a supplementary set of simulations at 0.25°-resolution confirms the robustness of our results and shows an additional reduction of the warm and dry bias over India. These findings highlight the strong sensitivity of the simulated ISM rainfall and its onset timing to the surface land heating pattern and amplitude, especially in the ME region. It also illustrates the key-role of land surface processes and horizontal resolution for improving the ISM representation, and more generally the monsoons, in current CGCMs.

  2. The influence of the geometry of the blade on the gradient of characteristic lines of side channel machines; Einfluss der Schaufelgeometrie auf den Kennliniengradienten von Seitenkanalmaschinen

    Energy Technology Data Exchange (ETDEWEB)

    Surek, D. [Fachhochschule Merseburg (Germany). Fachbereich Maschinenbau

    1998-10-01

    Side channel machines are mainly constructed with straight, radial arranged or forward writhed blades. The energy transfer from the impeller to the fluid medium is accomplished by the flow processes in the lateral open or semiopen impeller and in the side channel. With regard to a high and effective energy transfer the geometries of the impeller and the side channel have to be tuned one upon the other in order to reach high pressure coefficients, high gradients of the characteristic lines and high efficiencies. The geometries of the impeller and the blade are characterized by the outer and inner radii and the width of the impeller. The geometry of the blade is characterized by the ratio of the radii and the number of blades, especially the blade angle at the edge of the blade. Therefore some criteria of optimization will be given. (orig.) [Deutsch] Seitenkanalmaschinen werden vorwiegend mit geraden, radial angeordneten oder vorwaertsgekruemmten Laufschaufeln ausgefuehrt. Die Arbeitsuebertragung vom Laufrad an das Foerderfluid erfolgt durch die Stroemungsvorgaenge im seitlich offenen oder halboffenen Laufrad und im Seitenkanal. Mit Ruecksicht auf eine hohe und effektive Arbeitsuebertragung muessen die Laufrad- und Seitenkanalgeometrie aufeinander abgestimmt werden, wenn grosse Druckzahlen, grosse Kennliniengradienten und hohe Wirkungsgrade erreicht werden sollen. Die Laufrad- und Schaufelgeometrie werden durch die Aussen- und Innenradien und die Laufradbreite gekennzeichnet. Die Schaufelgeometrie wird durch das Radienverhaeltnis und die Schaufelzahl, insbesondere die Schaufelwinkel am Schaufelrand, charakterisiert. Dafuer werden einige Optimierungskriterien angegeben. (orig.)

  3. Current-voltage characteristics of quantum-point contacts in the closed-channel regime: Transforming the bias voltage into an energy scale

    DEFF Research Database (Denmark)

    Gloos, K.; Utko, P.; Aagesen, M.;

    2006-01-01

    .2 mu m) contacts are typically found to consist of very short (similar to 0.2 mu m) barriers. We have mapped the height of the barrier as a function of the gate voltage, and found that its behavior differs strongly from that extrapolated using conventional bias spectroscopy in the open-channel regime......We investigate the I(V) characteristics (current versus bias voltage) of side-gated quantum-point contacts, defined in GaAs/AlxGa1-xAs heterostructures. These point contacts are operated in the closed-channel regime, that is, at fixed gate voltages below zero-bias pinch-off for conductance. Our...... we are using the channel length remains the only adjustable parameter since the barrier height can be experimentally determined. For short (similar to 0.06 mu m) contacts, the I(V)-derived lengths agree rather well with those estimated from the geometrical layout, whereas nominally long (similar to 1...

  4. CONDUCTIVE CHANNEL FOR ENERGY TRANSMISSION

    Directory of Open Access Journals (Sweden)

    V. V. Apollonov

    2014-01-01

    Full Text Available Laser spark obtained by using a conical optics is much more appropriate to form conducting channels in atmosphere. Only two types of lasers are actively considered to be used in forming high-conductivity channels in atmosphere, controlled by laser spark: pulsed sub-microsecond gas and chemical lasers (CO2, DF and short pulse solid-state and UV lasers. Main advantage of short pulse lasers is their ability in forming of super long ionized channels with a characteristic diameter of ~100  µ  in atmosphere along the  beam propagation direction. At estimated electron densities below  10 ⋅ 16 cm–3 in these filaments and laser wavelengths in the range of 0,5–1,0 mm, the plasma barely absorbs laser radiation.  In this case, the length of the track composed of many filaments is determined by the laser intensity and may reach many kilometers at a femtosecond pulse energy of ~100 mJ. However, these lasers could not be used to form high-conductivity long channels in atmosphere. The ohmic resistance of this type a conducting channels turned out to be very high, and the gas in the channels could not be strongly heated (< 1 J. An electric breakdown controlled by radiation of femtosecond solid-state laser was implemented in only at a length of 3 m with a voltage of 2 MV across the discharge gap (670 kV/m.Not so long ago scientific group from P. N. Lebedev has improved that result, the discharge gap – 1 m had been broken under KrF laser irradiation when switching high-voltage (up to 390 kV/m electric discharge by 100-ns UV pulses. Our previous result  –  16 m long conducting channel controlled by a  laser spark at the voltage  –  3 MV  – was obtained more than 20 years ago in Russia and Japan by using pulsed CO2  laser with energy  –  0,5 kJ. An average electric field strength  was < 190 kV/m. It is still too much for efficient applications.

  5. Microstructural and mechanical characteristics of AlSiMnFe alloy processed by equal channel angular pressing

    OpenAIRE

    V. A. Andreyachshenko; Naizabekov, A. B.

    2016-01-01

    In the present research, equal channel angular pressing (ECAP) was conducted. The defectness degree of the alloy for one pass and maximum strain was determined. Ultra fine grained AlSiMnFe alloy was produced by refining grained annealed bulk by multi-pass ECAP at room temperature. The results reveal two regimes: from 1 to 2 passes the microstructure evolves to a equiaxed of ultrafine grains and from 2 to 4 passes there is no strict change in the average grain size.

  6. Microstructural and mechanical characteristics of AlSiMnFe alloy processed by equal channel angular pressing

    Directory of Open Access Journals (Sweden)

    V. A. Andreyachshenko

    2016-07-01

    Full Text Available In the present research, equal channel angular pressing (ECAP was conducted. The defectness degree of the alloy for one pass and maximum strain was determined. Ultra fine grained AlSiMnFe alloy was produced by refining grained annealed bulk by multi-pass ECAP at room temperature. The results reveal two regimes: from 1 to 2 passes the microstructure evolves to a equiaxed of ultrafine grains and from 2 to 4 passes there is no strict change in the average grain size.

  7. Is in-stream macrophyte growth predictable and what are its impacts on channel-averaged flow characteristics?

    Science.gov (United States)

    Jordan, David N.; Thomas, Robert E.; Keevil, Gareth M.; Parsons, Daniel R.; Hardy, Richard J.

    2016-04-01

    Understanding how the growth of aquatic vegetation impacts stage-discharge coupling is vital for river management planning. This study presents an annual record of monthly spatial distribution surveys of the in-stream macrophyte Ranunculus penicillatus coupled with channel form and flow velocity measurements, within a 50 m-long reach of a gravel-bed river. Whereas stage has varied by up to 0.4 m, there has been little change in channel form over the monitoring period (ongoing since 23/07/2014). Macrophyte growth continued from the start of the monitoring period until October 2014 when mean patch area was 6.74 m2, and then decreased throughout a decay phase until January 2015 when mean patch area was 1.12 m2. There was a 75.2% loss of macrophyte surface area between October 2014 and January 2015. The largest patches that remained in January 2015 continued to decay until February. Conversely, new macrophyte patches also began to recolonize the channel during this time. To our knowledge, this is the first evidence of a transition period during which aquatic vegetation is in both decay and recolonization phases simultaneously. In total 69% of patches present in January exhibited regrowth without further decay to form a base for recolonization. Therefore, the spatial distribution of macrophyte patches could be determined to be somewhat persistent. Despite this, due to several different growth factors, there are recognisable differences in both macrophyte patch shape and distribution when comparing data from July 2014 and July 2015, emphasising the unpredictability of macrophyte growth. The decay period of the Ranunculus p. coincided with seasonal high discharges in this catchment. Discharge remained high from January until March 2015, but then began to decrease, reflecting annual peaks in historical records for the study area. Large discharge variations were not matched by a large stage range. Displacement of water by vegetation growth maintained the stage height when

  8. Trend and characteristics of atmospheric emissions of Hg, As, and Se from coal combustion in China, 1980-2007

    Science.gov (United States)

    Tian, H. Z.; Wang, Y.; Xue, Z. G.; Cheng, K.; Qu, Y. P.; Chai, F. H.; Hao, J. M.

    2010-12-01

    Emissions of hazardous trace elements in China are of great concern because of their negative impacts on local air quality as well as on regional environmental health and ecosystem risks. In this paper, the atmospheric emissions of mercury (Hg), arsenic (As), and selenium (Se) from coal combustion in China for the period 1980-2007 are estimated on the basis of coal consumption data and emission factors, which are specified by different categories of combustion facilities, coal types, and the equipped air pollution control devices configuration (Dust collectors, FGD, etc.). Specifically, multi-year emission inventories of Hg, As, and Se from 30 provinces and 4 economic sectors (thermal power, industry, residential use, and others) are evaluated and analyzed in detail. Furthermore, the gridded distribution of provincial-based Hg, As, and Se emissions in 2005 at a resolution of 1° × 1° is also plotted. It shows that the calculated national total atmospheric emissions of Hg, As, and Se from coal combustion have rapidly increased from 73.59 t, 635.57 t, and 639.69 t in 1980 to 305.95 t, 2205.50 t, and 2352.97 t in 2007, at an annually averaged growth rate of 5.4%, 4.7%, and 4.9%, respectively. The industrial sector is the largest source for Hg, As, and Se, accounting for about 50.8%, 61.2%, and 56.2% of the national totals, respectively. The share of power plants is 43.3% for mercury, 24.9% for arsenic, and 33.4% for selenium, respectively. Also, it shows remarkably different regional contribution characteristics of these 3 types of trace elements, the top 5 provinces with the heaviest mercury emissions in 2007 are Shandong (34.40 t), Henan (33.63 t), Shanxi (21.14 t), Guizhou (19.48 t), and Hebei (19.35 t); the top 5 provinces with the heaviest arsenic emissions in 2007 are Shandong (219.24 t), Hunan (213.20 t), Jilin (141.21 t), Hebei (138.54 t), and Inner Mongolia (127.49 t); while the top 5 provinces with the heaviest selenium emissions in 2007 are Shandong (289

  9. Trend and characteristics of atmospheric emissions of Hg, As, and Se from coal combustion in China, 1980–2007

    Directory of Open Access Journals (Sweden)

    H. Z. Tian

    2010-09-01

    Full Text Available Emissions of hazardous trace elements in China are of great concern because of their negative impacts on local air quality as well as on regional environmental health and ecosystem risks. In this paper, the atmospheric emissions of mercury (Hg, arsenic (As, and selenium (Se from coal combustion in China for the period 1980–2007 are estimated on the basis of coal consumption data and emission factors, which are specified by different categories of combustion facilities, coal types, and the equipped air pollution control devices configuration (Dust collectors, FGD, etc.. Specifically, multi-year emission inventories of Hg, As, and Se from 30 provinces and 4 economic sectors (thermal power, industry, residential use, and others are evaluated and analyzed in detail. Furthermore, the gridded distribution of provincial-based Hg, As, and Se emissions in 2005 at a resolution of 1°×1° is also plotted. It shows that the calculated national total atmospheric emissions of Hg, As, and Se from coal combustion have rapidly increased from 73.59 t, 635.57 t, and 639.69 t in 1980 to 305.95 t, 2205.50 t, and 2352.97 t in 2007, at an annually averaged growth rate of 5.4%, 4.7%, and 4.9%, respectively. The industrial sector is the largest source for Hg, As, and Se, accounting for about 50.8%, 61.2%, and 56.2% of the national totals, respectively. The share of power plants is 43.3% for mercury, 24.9% for arsenic, and 33.4% for selenium, respectively. Also, it shows remarkably different regional contribution characteristics of these 3 types of trace elements, the top 5 provinces with the heaviest mercury emissions in 2007 are Shandong (34.40 t, Henan (33.63 t, Shanxi (21.14 t, Guizhou (19.48 t, and Hebei (19.35 t; the top 5 provinces with the heaviest arsenic emissions in 2007 are Shandong (219.24 t, Hunan (213.20 t, Jilin (141.21 t, Hebei (138.54 t, and Inner Mongolia (127.49 t; while the top 5 provinces with the heaviest selenium emissions in 2007 are Shandong

  10. Study of Channel Characteristics for Galvanic-Type Intra-Body Communication Based on a Transfer Function from a Quasi-Static Field Model

    Directory of Open Access Journals (Sweden)

    Min Du

    2012-11-01

    Full Text Available Intra-Body Communication (IBC, which modulates ionic currents over the human body as the communication medium, offers a low power and reliable signal transmission method for information exchange across the body. This paper first briefly reviews the quasi-static electromagnetic (EM field modeling for a galvanic-type IBC human limb operating below 1 MHz and obtains the corresponding transfer function with correction factor using minimum mean square error (MMSE technique. Then, the IBC channel characteristics are studied through the comparison between theoretical calculations via this transfer function and experimental measurements in both frequency domain and time domain. High pass characteristics are obtained in the channel gain analysis versus different transmission distances. In addition, harmonic distortions are analyzed in both baseband and passband transmissions for square input waves. The experimental results are consistent with the calculation results from the transfer function with correction factor. Furthermore, we also explore both theoretical and simulation results for the bit-error-rate (BER performance of several common modulation schemes in the IBC system with a carrier frequency of 500 kHz. It is found that the theoretical results are in good agreement with the simulation results.

  11. [Characteristics of Atmospheric Dry and Wet Deposition of Trace Metals in the Hinterland of the Three Gorges Reservoir, China].

    Science.gov (United States)

    Zhang, Liu-yi; Liu, Yuan; Qiao, Bao-qing; Fu, Chuan; Wang, Huan-bo; Huang, Yi-min; Yang, Fu-mo

    2016-02-15

    In order to investigate the characteristics of atmospheric trace metals deposition in the hinterland of the Three Gorges Reservoir, the wet and dry deposition samples were collected at an urban area sampling site in Wanzhou during January to June 2014. Besides, the samples were collected at five other sampling sites in April 2014 for comparative analysis, including factory region, town suburb, nature reserve, county suburb, and rural area. pH, conductivity, and trace metals (Al, As, B, Ba, Bi, Cd, Co, Cr, Cu, Fe, Li, Mn, Pb, Ni, Sb, Sr, Sn, Ti, Zn, V) were analyzed. In urban area, the acid rain frequency was 48.44% , and the acid rain occurred mainly in the period of January to April. The order of acid rain frequency in various functional areas was factory region > urban area > county suburb > town suburb > nature reserve > county rural area. All of the trace metals in wet deposition during the sampling period were lower than the National Environmental Quality Standard for Surface Water Standard of Class III. Cd, Cu, Ph and Zn were found exceeding the standard of class I , and the pollution in factory region was more serious compared to other functional areas. The extract pH of dry deposition in urban area was in the range of 4.91-6.74, with an average value of 5.79. The order of dry deposition in various functional areas was factory region > county suburb > urban area > county rural area > town suburb > nature reserve, which was exactly the same as that of the wet deposition, indicating the similar sources of dry and wet deposition. In urban area, the contents of Ba, Co, Cu, Cr, Li, Mn, Ni, Sr, Zn in dry deposition were greater than those in wet deposition, but the contents of Al, As, B, Bi, Cd, Fe, Ph, Sb, Sn, Ti, V showed the opposite trend. Analysis of the enrichment factors showed that Al was in moderate enrichment, while Bi and Cd were significantly enriched. PMID:27363132

  12. The affection analysis and compensation for atmospheric overfall in free space optical communication system

    Science.gov (United States)

    Yuan, Xiuhua; Wang, Jin; Huang, Dexiu; Liu, Deming

    2004-12-01

    The Free Space optical communication (FSO) or wireless optical communication, utilizes the atmospheric medium as transmission channel, where random variety such as fog, atomy and atmosphere flash and the atmospheric turbulence will badly affect the propagation of light, the receiving signal is easily swung and drifted with the change of weather. In this paper, we discussed the attenuation of the atmospheric channel and analyzed the signal characteristics in the condition of the atmospheric overfall, for the OOK modulation, discussed the receiving signal distribution in the atmospheric channel taking account for the noise gain of the light detector, and based on the principle of the Hartman-Shack sensor, we designed a wave-front distortion compensation system with fiber coupler. The signal fading resulted from wave-front phase distortion was compensated effectively by using the compensation system.

  13. Characteristic atmosphere-ocean-solid earth interactions in the Antarctic coastal and marine environment inferred from seismic and infrasound recording at Syowa Station, East Antarctica

    OpenAIRE

    Kanao, Masaki; Maggi, Alessia; Ishihara, Yoshiaki; Stutzmann, Eléonore; Yamamoto, Masa-Yuki; Toyokuni, Genti

    2013-01-01

    Several characteristic waves detected by seismographs in Antarctic stations have been recognized as originating from the physical interaction between the solid earth and the atmosphere-ocean-cryosphere system surrounding the Antarctic and may be used as a proxy for characterizing ocean wave climate. A Chaparral-type infrasound sensor was installed at Syowa Station (SYO; 39.6E, 69.0S), East Antarctica, in April 2008 during the International Polar Year (IPY2007-2008). Matching data are also ava...

  14. Distribution of velocity and turbulent characteristics in coarse-sediment laden flows above erodible plane bed in open channel

    Science.gov (United States)

    Zrostlík, Štěpán; Bareš, Vojtěch; Krupička, Jan; Picek, Tomáš; Matoušek, Václav

    2016-03-01

    Extreme conditions as flash floods in steep mobile-bed streams induce flows which carry a huge amount of sediment. Typically, the flow with the intense transport of sediment is stratified with a layered structure above an erodible plane bed. The paper deals with local flow characteristics in the layered structure of the two-phase flow composed of water and sediment. We present experimental data and results for two different fractions of plastic particles obtained using two acoustic Doppler methods and a Prandtl probe. The results contain vertical profiles of longitudinal velocity component and local turbulent characteristics of the flow as the Reynolds stress and turbulent intensity. The effect of the layered character of the flow on the flow characteristics is discussed. Special attention is paid to the distribution of Reynolds stress in the sediment-rich transport layer above the bed and to the evaluation of ability of carrier turbulent eddies to support sediment grains in and above the transport layer.

  15. Heat transfer characteristics of Fe3O4 ferrofluid flowing in a mini channel under constant and alternating magnetic fields

    International Nuclear Information System (INIS)

    Laminar forced convection heat transfer of water based Fe3O4 ferrofluid in a mini channel in the presence of constant and alternating magnetic fields is studied numerically. The hot ferrofluid flows into the 20 mm (l)×2 mm (h) mini channel with isothermal top and bottom cold surfaces and is subjected to a transverse non-uniform magnetic field produced by current carrying wires. Two-phase mixture model is implemented and the governing equations are solved using the finite volume approach. Primarily, the effects of the constant magnetic field location and intensity on the convective heat transfer are investigated. Simulation results show that the heat transfer is enhanced due to the disruption of the thermal boundary layer. However, this effect is more pronounced when the magnetic field source is placed in the fully developed region. In the next section, an alternating magnetic field with frequencies ranging from 0 to 10 Hz is imposed to the ferrofluid at different Reynolds numbers of Re=10, 25 and 50. A 16.48% heat transfer enhancement is obtained with a constant magnetic field at Re=25 and magnetic field intensity, Mn=1.07×108. This value is increased up to 27.72% by applying an alternating magnetic field with the same intensity at f=4 Hz. Results also indicate that the heat transfer enhancement due to the magnetic field is more significant at lower Reynolds numbers. The optimum frequency for heat transfer enhancement has been obtained for all the cases which shows that it has an increasing trend with the Reynolds number. - Highlights: • Ferrofluid forced convection heat transfer in a mini channel under constant and alternating magnetic fields is investigated numerically. • Heat transfer depends on Reynolds number, magnetic field location, intensity and frequency. • Heat transfer is enhanced noticeably campared to the case with no magnetic field. Enhancement is more significant when the magnetic field is placed in the fully developed region. • The

  16. 基于自然雷电的甚低频传播特性分析%Evaluation of P ropagation Characteristics of The VLF Channel With Lightning P ulse

    Institute of Scientific and Technical Information of China (English)

    张曙霞; 彭丹

    2015-01-01

    Lightning is one of the most important atmospheric phenomenon in nature, with tens of thousands of amperes of current, a few kilometers of the discharge distance, tens of microseconds of the duration time, abundant frequency compo⁃nents. Lightning pulses reach the distant receiver by multiple reflection in the VLF earth⁃ionosphere waveguide,so the re⁃ceived lightning pulses carry the propagation characteristics of the VLF channel in fact. In this work,we classify and count the lightning pulses firstly,then make spectrum analysis of the lightning pulses,finally make a comparison and analysis of the spectrum analysis and the prediction result of the LWPC. It shows that it’ s feasible to evaluate the propagation characteristics of the VLF channel with lightning pulse. Compared to the method of artificial radiation source,the main advantage is passive detection,low cost and wide frequency range,especially the measurement of the characteristics with high⁃precision in low fre⁃quency.%雷电是自然界最重要的大气现象之一,典型情况下雷电电流强度可达几万安培,放电路径可达几千米,持续时间几十微秒,包含非常丰富的频率成分,雷电脉冲在甚低频地—电离层波导中经多次反射到达远处的接收点,接收到的雷电脉冲实际携带了甚低频地—电离层波导频率传播特性。首先对雷电脉冲进行分类与统计,在此基础上对雷电脉冲进行频谱分析,然后将研究结果与LWPC软件预测结果进行对比分析。结果表明,使用自然雷电脉冲的平均谱估计甚低频传播特性是可行的。此法与人工辐射源法相比,主要优势在于被动检测、应用成本低、可测频率范围宽、低端频率特性测量精度较高。

  17. Numerical study of the MHD flow characteristics in a three-surface-multi-layered channel with different inlet conditions

    Energy Technology Data Exchange (ETDEWEB)

    Aoyagi, Mitsuhiro, E-mail: mao@karma.qse.tohoku.ac.jp; Ito, Satoshi; Hashizume, Hidetoshi

    2014-10-15

    A 3D MHD flow simulation was conducted to clarify the effects of the inlet flow conditions on the results of the validation experiment carried out previously and on the design window of the first wall using a three-surface-multi-layered channel. MHD pressure drop was largely influenced by the inlet condition. The numerical model with turbulent velocity profile showed qualitatively good agreement with the experimental result. The first wall temperature and pressure distributions obtained by the 3D simulation corresponded well to those obtained by the 2D simulation assuming fully developed flow. This suggested that complicated three-dimensional inlet flow condition generated in the L-shape elbow would not affects the existing design window.

  18. A stratification prediction diagram from characteristics of geometry, tides and runoff for estuaries with a prominent channel

    Digital Repository Service at National Institute of Oceanography (India)

    Vijith, V.; Shetye, S.R.

    -stratified to partially-mixed to well-mixed due to change in runoff from wet to dry season. Using data from 16 estuaries around the world, we show that the diagram can be used to distinguish characteristics of stratification and of forcing functions between estuaries....

  19. Characteristic X-ray radiation and Auger electrons from resonant coherently excited highly charged ions under channeling

    OpenAIRE

    Balashov, V.V.; Sokolik, A.; Stysin, A.

    2008-01-01

    Density-matrix approach to treat resonant coherent excitation of swift ions in oriented crystals is applied for unified theoretical description of charge state distribution of relativistic resonant coherently excited ions, their characteristic X-ray radiation and, as a new aspect, Auger electron production from doubly excited states.

  20. Non-stoichiometory and vaporization characteristic of Li2.1TiO3.05 in hydrogen atmosphere

    International Nuclear Information System (INIS)

    Lithium titanate (Li2TiO3) is one of the most promising candidates among the proposed solid breeder materials in fusion reactors because of its chemical satiability. Addition of H2 to inert sweep gas has been proposed for enhancing the release of bred tritium from breeder material. However, the mass of Li2TiO3 has been found to decrease with time in the hydrogen atmosphere. In order to control the mass change at the time of high-temperature use, development of Li2TiO3 which has excess Li2O is needed. Li2TiO3 (L100) and Li2.1TiO3.05 (L105) were prepared by solid-state reaction at 1273 K of Li2CO3 and TiO2 powders. In thermogravimetry, the masses of samples L100 and L105 were found to decrease with time in a hydrogen atmosphere, then to increase after a change of the atmosphere from hydrogen to oxygen. Sample L105 has fewer oxygen defects than L100. An atmosphere-controlled high-temperature mass spectrometer has provided the vapor pressure data for L100 and L105, under the conditions of D2 atmospheres. Sample L105 has a higher partial pressure of total Li-containing species than L100 above 1093 K

  1. A survey of benthic sediment contaminants in reaches of the Columbia River Estuary based on channel sedimentation characteristics

    Science.gov (United States)

    Counihan, Timothy D.; Waite, Ian R.; Nilsen, Elena B.; Hardiman, Jill M.; Elias, Edwin; Gelfenbaum, Guy; Zaugg, Steven D.

    2014-01-01

    While previous studies have documented contaminants in fish, sediments, water, and wildlife, few specifics are known about the spatial distribution of contaminants in the Columbia River Estuary (CRE). Our study goal was to characterize sediment contaminant detections and concentrations in reaches of the CRE that were concurrently being sampled to assess contaminants in water, invertebrates, fish, and osprey (Pandion haliaetus) eggs. Our objectives were to develop a survey design based on sedimentation characteristics and then assess whether sediment grain size, total organic carbon (TOC), and contaminant concentrations and detections varied between areas with different sedimentation characteristics. We used a sediment transport model to predict sedimentation characteristics of three 16 km river reaches in the CRE. We then compartmentalized the modeled change in bed mass after a two week simulation to define sampling strata with depositional, stable, or erosional conditions. We collected and analyzed bottom sediments to assess whether substrate composition, organic matter composition, and contaminant concentrations and detections varied among strata within and between the reaches. We observed differences in grain size fractions between strata within and between reaches. We found that the fine sediment fraction was positively correlated with TOC. Contaminant concentrations were statistically different between depositional vs. erosional strata for the industrial compounds, personal care products and polycyclic aromatic hydrocarbons class (Indus–PCP–PAH). We also observed significant differences between strata in the number of detections of Indus–PCP–PAH (depositional vs. erosional; stable vs. erosional) and for the flame retardants, polychlorinated biphenyls, and pesticides class (depositional vs. erosional, depositional vs. stable). When we estimated mean contaminant concentrations by reach, we observed higher contaminant concentrations in the furthest

  2. Distribution of velocity and turbulent characteristics in coarse-sediment laden flows above erodible plane bed in open channel

    Directory of Open Access Journals (Sweden)

    Zrostlík Štěpán

    2016-01-01

    Full Text Available Extreme conditions as flash floods in steep mobile-bed streams induce flows which carry a huge amount of sediment. Typically, the flow with the intense transport of sediment is stratified with a layered structure above an erodible plane bed. The paper deals with local flow characteristics in the layered structure of the two-phase flow composed of water and sediment. We present experimental data and results for two different fractions of plastic particles obtained using two acoustic Doppler methods and a Prandtl probe. The results contain vertical profiles of longitudinal velocity component and local turbulent characteristics of the flow as the Reynolds stress and turbulent intensity. The effect of the layered character of the flow on the flow characteristics is discussed. Special attention is paid to the distribution of Reynolds stress in the sediment-rich transport layer above the bed and to the evaluation of ability of carrier turbulent eddies to support sediment grains in and above the transport layer.

  3. Impacts of teachers’ competency on job performance in research universities with industry characteristics: Taking academic atmosphere as moderator

    OpenAIRE

    Anguo Xu; Long Ye

    2014-01-01

    Purpose: Research universities with industry characteristics play an irreplaceable role in national economic development and social development. With the rapid development of research universities with industry characteristics in China, these universities face new challenges in managing teachers and promoting their quality. This paper aims to examine the impact of teachers’ competency on job performance in research university with industry characteristics Design/methodology/approach: Based on...

  4. Experimental investigation on characteristics of the interfacial wave for the droplet generation in a horizontal rectangular channel

    International Nuclear Information System (INIS)

    Recently, KAERI (Korea Atomic Energy Research Institute) proposed a new mechanistic droplet generation model for the SPACE code. However, it is required to determine three coefficients regarding to the interfacial wave in the stratified flow condition. The main measurement parameters to be needed for the coefficients are the wave slope, liquid fraction, wave hypotenuse length, wave velocity, wave frequency, wavelength, and droplet size. In this study experiments were conducted to measure those parameters with PIV laser system in a horizontal rectangular channel under the air-water flow condition. Experimental investigation was performed for the measurement of parameters related to the interfacial wave when droplets were generated in the air-water stratified flow condition. From the tests, wave slope, liquid fraction, wave hypotenuse length, wave frequency, wave velocity, and droplet size were measured. Finally, we determined three coefficients for the mechanistic droplet generation model which was proposed by KAERI. An additional study will be performed for the extension of database and model coefficients for the droplet generation in the future

  5. Direct numerical simulation of the turbulent MHD channel flow at low magnetic Reynolds number for electric correlation characteristics

    Institute of Scientific and Technical Information of China (English)

    LEE; ChunHian

    2010-01-01

    Direct numerical simulation (DNS) of incompressible magnetohydrodynamic (MHD) turbulent channel flow has been performed under the low magnetic Reynolds number assumption.The velocity-electric field and electric-electric field correlations were studied in the present work for different magnetic field orientations.The Kenjeres-Hanjalic (K-H) model was validated with the DNS data in a term by term manner.The numerical results showed that the K-H model makes good predictions for most components of the velocity-electric field correlations.The mechanisms of turbulence suppression were also analyzed for different magnetic field orientations utilizing the DNS data and the K-H model.The results revealed that the dissipative MHD source term is responsible for the turbulence suppression for the case of streamwise and spanwise magnetic orientation,while the Lorentz force which speeds up the near-wall fluid and decreases the production term is responsible for the turbulence suppression for the case of the wall normal magnetic orientation.

  6. Flooding in a thin rectangular slit geometry representative of ATR fuel assembly side-plate flow channels

    International Nuclear Information System (INIS)

    Air-water counter-current flow limit experiments were conducted in thin rectangular channels at atmospheric pressure. The parameters were: narrow channel width, either 1.1 mm or 2.2 mm; inlet water temperature, ranging from 294 K to 330 K; channel surface condition, either clean aluminum, aluminum oxide, or acrylic; location and geometry of the air inlet; method of forcing air through the channel; and liquid head above the channel. Experimental results for each set of parameters can be linearly correlated using the square root of the non-dimensional superficial velocities. Channel surface wetting and location and geometry of the air injection had the greatest effect. Narrow channel width, water temperature, method used to force air through the channel, and liquid head above the channel had little effect on the flooding characteristics. ((orig.))

  7. Effects of the modified atmosphere and irradiation on the microbiological, physical-chemical and sensory characteristics of the 'minas frescal' cheese

    International Nuclear Information System (INIS)

    The experiment was divided into two parts. Initially, it was studied the 'Minas Frescal' cheeses packed under atmospheric air, modified atmosphere of 70% CO2 and 30% N2 (ATM) and vacuum. Second the cheeses packed under these three treatments had been radiated by doses of 2 KGy. In the two parts of the experiment, it was analyzed the microbial evolution and, the sensory and physical-chemical characteristics of the cheeses under the different treatments during a 4 deg C-storage. In the first phase of the experiment it was verified that the ATM and the vacuum decreased the intensity of the total population growth of aerobic mesophilic and psychotropic and had reduced the population of Staphylococcus positive coagulase, but they had not been efficient controlling the total coliforms and Escherichia coli, while in control all the populations had continuously grown, according to the sensory characteristics of the cheeses, color, odor and appearance. These characteristics were kept the same during the 40 days of storage, and the control decreased the acceptability levels gradually, being rejected in the 17th day. In the second part of the experiment, it was observed that a 2KGy-irradiation over the 'Minas Frescal' cheeses reduced the populations of aerobic mesophilic, aerobic and anaerobic psychotropic, Staphylococcus positive coagulase, total coliforms and Escherichia coli. The ATM and vacuum treatments were very efficient therefore they prevented the growth of these microorganisms during the storage, while in control, the aerobic mesophilic and psychotropic population grew during the storage. According to sensory aspects, the ATM treatment was the most efficient one, because it kept the appearance, texture and flavor for more than 43 days while the vacuum kept for 36 days and the control for only 8 days. The use of the irradiation with modified atmosphere and low temperatures of storage increased the shelf life of the cheeses, hindering the growth of the microbial

  8. Deposition and Mineralogical Characteristics of Atmospheric Dust in relation to Land Use and Land Cover Change in Delhi (India

    Directory of Open Access Journals (Sweden)

    Bablu Kumar

    2014-01-01

    Full Text Available This study highlights that the increasing urbanization and industrialization in Delhi are responsible for higher fluxes of atmospheric dust and its chemical constituents. Delhi has experienced a drastic change in land use and land cover area during the past two decades. Road lengths of the city have increased by 76% from 1985 to 2011. The number of mobile vehicles has reached 80,52,508 in 2014 from 24,32,295 in 1994. The industrial units in Delhi have increased by 39.54% in 2011 as compared to 1994 value. Atmospheric dust which is originated from soil in this region becomes carbon rich due to interaction of suspended soil with atmospheric pollutants. Emissions of carbonaceous aerosols from coal and petroleum combustions are mainly responsible for silica dominated soil dust transforming into carbon rich particulate matter. Such dust may play very important role in the atmosphere having significant influence on human health, global warming, climate change, radiative forcing, visibility, and cloud formation. It is expected that if the rate of development remains the same, green cover of the city invariably will be sized down in order to meet the demand of housing, transportation, industries, and so forth in proportion to the rising population.

  9. A study on characteristics and sources of winter time atmospheric aerosols in Kyoto and Seoul using PIXE and supplementary analysis

    International Nuclear Information System (INIS)

    Atmospheric aerosols were collected using a two stages filter sampler to classify into the fine and coarse fraction in Kyoto and Seoul in winter season. Elemental concentrations of aerosols were analyzed by PIXE and EAS as well as ion concentrations by IC. Analyzed data were used to source of aerosol particles. (author)

  10. Relation between Dispersion Characteristics over Surfaces with Dissimilar Roughness and Atmospheric Stability, under Conditions of Equal Geostrophic Winds

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Larsen, Søren Ejling

    1981-01-01

    A simple model was described that related the dispersion of material from ground-level sources at 2 areas, taking into account dissimilarities in the surface roughness parameter (z0) and the atmospheric stability characterized by the Monin-Obukhov length (L). The geostrophic wind speed was assumed...

  11. Relation between burnout and differential pressure fluctuation characteristics by the disturbance waves near the flow obstacle in a vertical annular channel

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Shoji; Fukano, Tohru [Kyushu Univ., Graduate School of Engineering, Fukuoka (Japan)

    2002-07-01

    If a flow obstruction such as a spacer is set in a boiling two-phase flow within an annular channel, the inner tube of which is used as a heater, the temperature on the surface of the heater tube is severely affected by the existence of the spacer. In some cases the spacer has a cooling effect, and in the other case it causes the dryout of the cooling liquid film on the heating surface resulting in the burnout of the tube. But the thermo-fluid dynamic mechanism to cause burnout near the spacer is not still clear. In the present paper we discuss temperature fluctuation characteristics in relation to the change of the differential pressure across the spacer caused by the passing of the disturbance waves in case that the burnout generates. (author)

  12. Relation between burnout and differential pressure fluctuation characteristics by the disturbance waves near the flow obstacle in a vertical annular channel

    International Nuclear Information System (INIS)

    If a flow obstruction such as a spacer is set in a boiling two-phase flow within an annular channel, the inner tube of which is used as a heater, the temperature on the surface of the heater tube is severely affected by the existence of the spacer. In some cases the spacer has a cooling effect, and in the other case it causes the dryout of the cooling liquid film on the heating surface resulting in the burnout of the tube. But the thermo-fluid dynamic mechanism to cause burnout near the spacer is not still clear. In the present paper we discuss temperature fluctuation characteristics in relation to the change of the differential pressure across the spacer caused by the passing of the disturbance waves in case that the burnout generates. (author)

  13. Noise Characteristics of 64-channel 2nd-order DROS Gradiometer System inside a Poorly Magnetically-shielded Room

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. M.; Lee, Y. H.; Yu, K. K.; Kim, K.; Kwon, H.; Park, Y. K. [Biosignal Research Center, Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Sasada, Ichiro [Dept. of Applied Science for Electronics and Materials, Ktushu University, Fukuoka (Korea, Republic of)

    2006-10-15

    We have developed a second-order double relaxation oscillation SQUID(DROS) gradiometer with a baseline of 35 mm, and constructed a poorly magnetically-shielded room(MSR) with an aluminum layer and permalloy layers for magnetocardiography(MCG). The 2nd-order DROS gradiometer has a noise level of 20 fT/Hz at 1 Hz and 8 fT/Hz at 200 Hz inside the heavily-shielded MSR with a shielding factor of10{sup 3}at 1 Hz and 10{sup 4} - 10{sup 5} at 100 Hz. The poorly-shielded MSR, built of a 12-mm-thick aluminum layer and 4-6 permalloy layers of 0.35 mm thickness, is 2.4 m x 2.4 m x 2.4 m in size, and has a shielding factor of 40 at 1 Hz, 10{sup 4} at 100 Hz. Our 64-channel second-order gradiometer MCG system consists of 64 2nd-order DROS gradiometers, flux-locked loop electronics, and analog signal processors. With the 2nd-order DROS gradiometers and flux-locked loop electronics installed inside the poorly-shielded MSR, and with the analog signal processor installed outside it, the noise level was measured to be 20 fT/Hz at 1 Hz and 8 fT/Hz at 200 Hz on the average even though the MSR door is open. This result leads to a low noise level, low enough to obtain a human MCG at the same level as that measured in the heavily-shielded MSR. However, filters or active shielding is needed fur clear MCG when there is large low-frequency noise from heavy air conditioning or large ac power consumption near the poorly-shielded MSR.

  14. The Effects of Sequential Environmental and Harvest Stressors on the Sensory Characteristics of Cultured Channel Catfish (Ictalurus Punctatus) Fillets.

    Science.gov (United States)

    Ciaramella, Michael A; Kim, Taejo; Avery, Jimmy L; Allen, Peter J; Schilling, M Wes

    2016-08-01

    Stress during fish culture alters physiological homeostasis and affects fillet quality. Maintenance of high-quality seafood is important to ensure the production of a marketable product. This study assessed how sequential stressors affect the sensory and quality characteristics of catfish (Ictalurus punctatus) fillets. Three stress trials were conducted where temperature (25 or 33 °C) and dissolved oxygen (DO, approximately 2.5 or >5 mg/L) were manipulated followed by socking and transport stress. After each stage of harvest (environmental stress, socking, and transport), fillet yield, consumer acceptability, descriptive evaluation, cook loss, tenderness, and pH were evaluated. Fillet yield decreased with increasing severity of environmental stress. Fillets from the severe stress treatment (33 °C, approximately 2.5 mg/L) received the highest acceptability scores (P 5 mg/L) were the least acceptable (P 6 on a 9 point scale). Socking and transport were identified to positively affect textural characteristics of catfish fillets. Although the effects observed were not likely to negatively impact consumer acceptance, a strict management plan should be followed to maintain consistency in the product and avoid changes in stressors that might alter quality more drastically. PMID:27333086

  15. Hydrothermal synthesis and characteristics of 3-D hydrated bismuth oxalate coordination polymers with open-channel structure

    International Nuclear Information System (INIS)

    Two new 3-D porous bismuth coordination polymers, (C5NH6)2[Bi2(H2O)2(C2O4)4].2H2O 1 and (NH4)[Bi(C2O4)2].3H2O 2, have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic symmetry, P21/c space group with a=10.378(2) A, b=17.285(3) A, c=16.563(5) A, α=90 deg., β=119.66(2) deg., γ=90 deg., V=2581.8(10) A3, Z=4, R1=0.0355 and wR2=0.0658 for unique 4713 reflections I >2σ(I). Compound 2 crystallizes in the tetragonal symmetry, I41/amd space group with a=11.7026(17) A, b=11.7026(17) A, c=9.2233(18) A, α=90 deg., β=90 deg., γ=90 deg., V=1263.1(4) A3, Z=32, R1=0.0208 and wR2=0.0518 for unique 359 reflections I> 2σ(I). Compounds 1 and 2 are 3-D open-framework structures with a 66 uniform net, which consist of honeycomb-like layers connected to each other by oxalate units. While different guest molecules fill in their cavities of honeycomb-like layers, study of ultrasonic treatment on 2 indicates the replacement of NH4+ by K+ on potassium ion exchange. Thermogravimetric analysis indicates that the open-channel frameworks are thermally stable up to 200 deg. C, and other characterizations are also described by elemental analysis, IR and ultraviolet-visible diffuse reflectionintegral spectrum (UV-Vis DRIS). - Graphical abstract: Two novel 3-D extended porous coordination polymers have been synthesized by hydrothermal method. Both compounds are 3-D open-framework structures with a 66 uniform net, which consist of honeycomb-like layers connected to each other by oxalate units. While different guest molecules fill in their cavities of honeycomb-like layers. Study of ultrasonic treatment on 2 indicates the replacement of NH4+ by K+ on potassium ion exchange

  16. Sol-gel modified poly(dimethylsiloxane) microfluidic devices with high electroosmotic mobilities and hydrophilic channel wall characteristics.

    Science.gov (United States)

    Roman, Gregory T; Hlaus, Tyler; Bass, Kevin J; Seelhammer, Todd G; Culbertson, Christopher T

    2005-03-01

    Using a sol-gel method, we have fabricated poly(dimethylsiloxane) (PDMS) microchips with SiO2 particles homogeneously distributed within the PDMS polymer matrix. These particles are approximately 10 nm in diameter. To fabricate such devices, PDMS (Sylgard 184) was cast against SU-8 molds. After curing, the chips were carefully removed from the mold and sealed against flat, cured pieces of PDMS to form enclosed channel manifolds. These chips were then solvated in tetraethyl orthosilicate (TEOS), causing them to expand. Subsequently, the chips were placed in an aqueous solution containing 2.8% ethylamine and heated to form nanometer-sized SiO2 particles within the cross-linked PDMS polymer. The water contact angle for the PDMS-SiO2 chips was approximately 90.2 degrees compared to a water contact angle for Sylgard 184 of approximately 108.5 degrees . More importantly, the SiO2 modified PDMS chips showed no rhodamine B absorption after 4 h, indicating a substantially more hydrophilic and nonabsorptive surface than native PDMS. Initial electroosmotic mobilities (EOM) of (8.3+/-0.2)x10(-4) cm2/(V.s) (RSD=2.6% (RSD is relative standard deviation); n=10) were measured. This value was approximately twice that of native Sylgard 184 PDMS chips (4.21+/-0.09)x10(-4) cm2/(V.s) (RSD=2.2%; n=10) and 55% greater than glass chips (5.3+/-0.4)x10(-4) cm2/(V.s) (RSD=7.7%; n=5). After 60 days of dry storage, the EOM was (7.6+/-0.3)x10(-4) cm2/(V.s) (RSD=3.9%; n=3), a decrease of only 8% below that of the initially measured value. Separations performed on these devices generated 80,000-100,000 theoretical plates in 6-14 s for both tetramethylrhodamine succidimidyl ester and fluorescein-5-isothiocyanate derivatized amino acids. The separation distance was 3.5 cm. Plots of peak variance vs analyte migration times gave diffusion coefficients which indicate that the separation efficiencies are within 15% of the diffusion limit. PMID:15732926

  17. Gramicidin Channels: Versatile Tools

    Science.gov (United States)

    Andersen, Olaf S.; Koeppe, Roger E., II; Roux, Benoît

    Gramicidin channels are miniproteins in which two tryptophan-rich subunits associate by means of transbilayer dimerization to form the conducting channels. That is, in contrast to other ion channels, gramicidin channels do not open and close; they appear and disappear. Each subunit in the bilayer-spanning channel is tied to the bilayer/solution interface through hydrogen bonds that involve the indole NH groups as donors andwater or the phospholipid backbone as acceptors. The channel's permeability characteristics are well-defined: gramicidin channels are selective for monovalent cations, with no measurable permeability to anions or polyvalent cations; ions and water move through a pore whose wall is formed by the peptide backbone; and the single-channel conductance and cation selectivity vary when the amino acid sequence is varied, even though the permeating ions make no contact with the amino acid side chains. Given the plethora of available experimental information—for not only the wild-type channels but also for channels formed by amino acid-substituted gramicidin analogues—gramicidin channels continue to provide important insights into the microphysics of ion permeation through bilayer-spanning channels. For similar reasons, gramicidin channels constitute a system of choice for evaluating computational strategies for obtaining mechanistic insights into ion permeation through the more complex channels formed by integral membrane proteins.

  18. Study of orbital angular momentum entangled photons entanglement in atmospheric channel%大气信道中单光子轨道角动量纠缠特性的研究

    Institute of Scientific and Technical Information of China (English)

    李铁; 谌娟; 柯熙政; 吕宏

    2012-01-01

    In this paper, we describe orbital angular momentum entangled photon pair entanglement in atmospheric channel. The Von Karman spectrum of turbulence is used to create a model of two-photon pair entanglement. The effects of atmospheric turbulence on the entanglement of entangled photon pairs of different orbital angular momentum bases are analyzed. The obtained results are as follows because of the presence of atmospheric turbulence, the entanglement of entangled photon pairs decreases with the increase of the propagation distance z in the atmosphere channel. The entanglement of the entangled photon pairs decreases with the increase of transmission distance. The bigger the turbulence intensity, the faster the entanglement decline and the shorter the propagation distanceis. In the same intensity of atmospheric turbulence of the atmospheric channel, the bigger the orbital angular momentum index, the slower the entanglement decline and the further the propagation distanceis.%本文讨论了大气信道中轨道角动量纠缠光子对的纠缠度,并利用vonKarman大气湍流谱来建立双光子纠缠度的模型,分析了大气湍流对不同轨道角动量纠缠光子对纠缠度的影响.研究表明:在大气信道中,由于大气湍流的存在,纠缠光子对的纠缠度随着传输距离Z的增加而减小;大气湍流强度越大,纠缠光子对的纠缠度下降的越快,纠缠光子对传输的距离越小;在湍流强度相同的大气信道轨道角动量指数越大的纠缠光子对,纠缠度下降得越慢,纠缠光子对传输的距离越远.

  19. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    OpenAIRE

    Petzold, A.; Hasselbach, J.; P. Lauer; Baumann, R.; Franke, K.; Gurk, C.; H. Schlager; Weingartner, E.

    2008-01-01

    Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL) were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transform...

  20. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    OpenAIRE

    Petzold, A.; Hasselbach, J.; P. Lauer; Baumann, R.; Franke, K.; Gurk, C.; H. Schlager; Weingartner, E.

    2007-01-01

    Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL) were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B{&}W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transfo...

  1. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    OpenAIRE

    Petzold, A.; Hasselbach, J.; P. Lauer; Baumann, R.; Franke, K.; Gurk, C.; H. Schlager; Weingartner, E.

    2007-01-01

    Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL) were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aer...

  2. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    OpenAIRE

    Petzold, Andreas; Hasselbach, Jan; Lauer, Peter; Baumann, Robert; Franke, Klaus; Gurk, Christian; Schlager, Hans; Weingartner, Ernest

    2008-01-01

    International audience Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL) were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airb...

  3. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    OpenAIRE

    Petzold, A.; Hasselbach, J.; P. Lauer; Baumann, R.; Franke, K.; Gurk, C.; H. Schlager; Weingartner, E.

    2007-01-01

    International audience Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL) were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B{&}W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by ai...

  4. Trend and characteristics of atmospheric emissions of Hg, As, and Se from coal combustion in China, 1980–2007

    OpenAIRE

    H. Z. Tian; Wang, Y.; Xue, Z G; Cheng, K.; Qu, Y. P.; Chai, F. H; J. M. Hao

    2010-01-01

    Emissions of hazardous trace elements in China are of great concern because of their negative impacts on local air quality as well as on regional environmental health and ecosystem risks. In this paper, the atmospheric emissions of mercury (Hg), arsenic (As), and selenium (Se) from coal combustion in China for the period 1980–2007 are estimated on the basis of coal consumption data and emission factors, which are specified by different categories of combustion facilities, coal types, and the ...

  5. Trend and characteristics of atmospheric emissions of Hg, As, and Se from coal combustion in China, 1980–2007

    OpenAIRE

    H. Z. Tian; Wang, Y.; Xue, Z G; Cheng, K.; Qu, Y. P.; Chai, F. H; J. M. Hao

    2010-01-01

    Emissions of hazardous trace elements in China are of great concern because of their negative impacts on local air quality as well as on regional environmental health and ecosystem risks. In this paper, the atmospheric emissions of mercury (Hg), arsenic (As), and selenium (Se) from coal combustion in China for the period 1980–2007 are estimated on the basis of coal consumption data and emission factors, which are specified by different categories of combustion facilities, co...

  6. Interpretations of the Surficial Geology from National Oceanic and Atmospheric Administration (NOAA) Survey H11079 of Great Round Shoal Channel, MA (H11079_SURFGEOL.SHP, Geographic)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA) and the Massachusetts Office of Coastal Zone...

  7. H11079_GEO_B: 3-m Bathymetric Grid of National Oceanic and Atmospheric Administration (NOAA) Survey H11079 of Great Round Shoal Channel, Offshore Massachusetts (Geographic)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA) and the Massachusetts Office of Coastal Zone...

  8. Task-based detectability comparison of exponential transformation of free-response operating characteristic (EFROC) curve and channelized Hotelling observer (CHO)

    Science.gov (United States)

    Khobragade, P.; Fan, Jiahua; Rupcich, Franco; Crotty, Dominic J.; Gilat Schmidt, Taly

    2016-03-01

    This study quantitatively evaluated the performance of the exponential transformation of the free-response operating characteristic curve (EFROC) metric, with the Channelized Hotelling Observer (CHO) as a reference. The CHO has been used for image quality assessment of reconstruction algorithms and imaging systems and often it is applied to study the signal-location-known cases. The CHO also requires a large set of images to estimate the covariance matrix. In terms of clinical applications, this assumption and requirement may be unrealistic. The newly developed location-unknown EFROC detectability metric is estimated from the confidence scores reported by a model observer. Unlike the CHO, EFROC does not require a channelization step and is a non-parametric detectability metric. There are few quantitative studies available on application of the EFROC metric, most of which are based on simulation data. This study investigated the EFROC metric using experimental CT data. A phantom with four low contrast objects: 3mm (14 HU), 5mm (7HU), 7mm (5 HU) and 10 mm (3 HU) was scanned at dose levels ranging from 25 mAs to 270 mAs and reconstructed using filtered backprojection. The area under the curve values for CHO (AUC) and EFROC (AFE) were plotted with respect to different dose levels. The number of images required to estimate the non-parametric AFE metric was calculated for varying tasks and found to be less than the number of images required for parametric CHO estimation. The AFE metric was found to be more sensitive to changes in dose than the CHO metric. This increased sensitivity and the assumption of unknown signal location may be useful for investigating and optimizing CT imaging methods. Future work is required to validate the AFE metric against human observers.

  9. Heavy metal enrichment characteristics in ash of municipal solid waste combustion in CO2/O2 atmosphere.

    Science.gov (United States)

    Tang, YuTing; Ma, XiaoQian; Yu, QuanHeng; Zhang, Can; Lai, Zhiyi; Zhang, Xiaoshen

    2015-09-01

    This paper investigated the behavior of six heavy metals (Cd, Pb, Cu, Cr, Ni and Zn) in the bottom ashes of recycled polyvinyl chloride pellets (PVC), wood sawdust (WS) and paper mixture (PM), representing the common components of municipal solid waste (MSW), obtained during combustion in CO2/O2 atmosphere in a lab-scale electrically heated tube furnace. Replacement of N2 by CO2 did not obviously change the shape of relative enrichment factor (RE) curves and subsequent order of heavy metals, but increased enrichment of these heavy metals in bottom ashes of WS, PM and PVC. The increment of O2 concentration in CO2/O2 atmosphere further increased RE values. It was only when the temperature was higher than or equal to 700°C that the increment of the combustion temperature reduced the RE values of heavy metals. The effect of temperature on heavy metals evaporation was the most pronounced for the medium volatile metal Pb, and the least for the low volatiles Cr and Ni. The effect of temperature was more pronounced for PVC ash than for WS and PM ashes. This paper contributes to the control of heavy metals during MSW incineration and management of MSW oxy-fuel residues. PMID:26130169

  10. Atmospheric concentration characteristics and gas-particle partitioning of PCBs in a rural area of eastern Germany

    Energy Technology Data Exchange (ETDEWEB)

    Mandalakis, Manolis [Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, P.O. Box 2208, GR-71003, Heraklion (Greece)]. E-mail: mandalakis@chemistry.uoc.gr; Stephanou, Euripides G. [Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, P.O. Box 2208, GR-71003, Heraklion (Greece)

    2007-05-15

    Atmospheric concentrations of polychlorinated biphenyls (PCBs) were measured in 14 successive daytime and nighttime air samples collected from Melpitz, a rural site in eastern Germany. The average total concentration of PCBs was 110+/-80pgm{sup -3} and they were predominately present in the gas phase ({approx}95%). Composition of individual congeners closely resembled those of Clophen A30 and Aroclor 1232. Partial vapor pressures of PCBs were well correlated with temperature and the steep slopes obtained from Clausius-Clapeyron plots (-4500 to -8000) indicated that evaporation from adjacent land surfaces still controls the atmospheric levels of these pollutants. Particle-gas partitioning coefficients (K{sub P}) of PCBs were well correlated with the respective sub-cooled vapor pressures (P{sub L}{sup o}), but the slopes obtained from logK{sub P} versus logP{sub L}{sup o} plots (-0.16 to -0.59) deviated significantly from the expected value of -1. Overall, gas-particle partitioning of PCBs was better simulated by Junge-Pankow than octanol/air partition coefficient-based model.

  11. The back-diffusion effect of air on the discharge characteristics of atmospheric-pressure radio-frequency glow discharges using bare metal electrodes

    International Nuclear Information System (INIS)

    Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas using bare metal electrodes have promising prospects in the fields of plasma-aided etching, deposition, surface treatment, disinfection, sterilization, etc. In this paper, the discharge characteristics, including the breakdown voltage and the discharge voltage for sustaining a stable and uniform α mode discharge of the RF APGD plasmas are presented. The experiments are conducted by placing the home-made planar-type plasma generator in ambient and in a vacuum chamber, respectively, with helium as the primary plasma-forming gas. When the discharge processes occur in ambient, particularly for the lower plasma-working gas flow rates, the experimental measurements show that it is the back-diffusion effect of air in atmosphere, instead of the flow rate of the gas, that results in the obvious decrease in the breakdown voltage with increasing plasma-working gas flow rate. Further studies on the discharge characteristics, e.g. the luminous structures, the concentrations and distributions of chemically active species in plasmas, with different plasma-working gases or gas mixtures need to be conducted in future work

  12. The back-diffusion effect of air on the discharge characteristics of atmospheric-pressure radio-frequency glow discharges using bare metal electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Sun Wenting; Liang Tianran; Wang Huabo; Li Heping; Bao Chengyu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2007-05-15

    Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas using bare metal electrodes have promising prospects in the fields of plasma-aided etching, deposition, surface treatment, disinfection, sterilization, etc. In this paper, the discharge characteristics, including the breakdown voltage and the discharge voltage for sustaining a stable and uniform {alpha} mode discharge of the RF APGD plasmas are presented. The experiments are conducted by placing the home-made planar-type plasma generator in ambient and in a vacuum chamber, respectively, with helium as the primary plasma-forming gas. When the discharge processes occur in ambient, particularly for the lower plasma-working gas flow rates, the experimental measurements show that it is the back-diffusion effect of air in atmosphere, instead of the flow rate of the gas, that results in the obvious decrease in the breakdown voltage with increasing plasma-working gas flow rate. Further studies on the discharge characteristics, e.g. the luminous structures, the concentrations and distributions of chemically active species in plasmas, with different plasma-working gases or gas mixtures need to be conducted in future work.

  13. The back-diffusion effect of air on the discharge characteristics of atmospheric-pressure radio-frequency glow discharges using bare metal electrodes

    Science.gov (United States)

    Sun, Wen-Ting; Liang, Tian-Ran; Wang, Hua-Bo; Li, He-Ping; Bao, Cheng-Yu

    2007-05-01

    Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas using bare metal electrodes have promising prospects in the fields of plasma-aided etching, deposition, surface treatment, disinfection, sterilization, etc. In this paper, the discharge characteristics, including the breakdown voltage and the discharge voltage for sustaining a stable and uniform α mode discharge of the RF APGD plasmas are presented. The experiments are conducted by placing the home-made planar-type plasma generator in ambient and in a vacuum chamber, respectively, with helium as the primary plasma-forming gas. When the discharge processes occur in ambient, particularly for the lower plasma-working gas flow rates, the experimental measurements show that it is the back-diffusion effect of air in atmosphere, instead of the flow rate of the gas, that results in the obvious decrease in the breakdown voltage with increasing plasma-working gas flow rate. Further studies on the discharge characteristics, e.g. the luminous structures, the concentrations and distributions of chemically active species in plasmas, with different plasma-working gases or gas mixtures need to be conducted in future work.

  14. [Pollution characteristics and source of the atmospheric fine particles and secondary inorganic compounds at Mount Dinghu in autumn season].

    Science.gov (United States)

    Liu, Zi-Rui; Wang, Yue-Si; Liu, Quan; Liu, Lu-Ning; Zhang, De-Qiang

    2011-11-01

    Real-time measurements of PM2.5, secondary inorganic compounds in PM2.5 (SO4(2-), NH4(+), and NO3(-)) and related gaseous pollutants were conducted at Mount Dinghu, a regional background station of the Pearl River Delta (PRD), in October and November 2008 by using a conventional R&P TEOM and a system of rapid collection of fine particles and ion chromatography (RCFP-IC). Sources and transportation of atmospheric particles during the experiment were discussed with principal component analysis and backward trajectories calculated using HYSPLIT model. The average daily mass concentrations of PM2.5 were 76.9 microg x m(-3) during sampling period, and average daily mass concentrations of SO4(2-), NH4(+), and NO3(-) were 20.0 microg x m(-3), 6.8 microg x m(-3) and 2.6 microg x m(-3), respectively. The sum of these three secondary inorganic compounds accounted for more than one third of the PM2.5 mass concentration, which had become the major source of atmospheric fine particles at Mount Dinghu. The diurnal variation of PM2.5, SO4(2-), and NH4(+) all showed a "bimodal" distribution with two peaks appeared at 10:00 am and at 16:00 pm, respectively, whereas NO3(-s) howed "single peak" distribution peaked at 10:00 am. The mass concentrations of SO4(2-) in PM2.5 had the similar diurnal variation with that of SO2, SO4(2-) in PM2.5 was mainly transformed from SO2, whereas NO3(-) showed difference diurnal variation with that of NO2, and the second conversion rate of NO2 was far lower than that of SO2. NH4(+) in PM2.5 existed mainly in the form of sulfate, nitrate and chloride. Both of principal component analysis and back trajectory analysis showed that the variations of PM2.5 and secondary inorganic compounds at Mount Dinghu were mainly affected by the long-range transport air mass passed over Guangzhou, Huizhou and other highly industrialized areas which carried air pollutants to the observation site, at the same time local sulfate originated from secondary formation also

  15. [Spectral analyzing effects of atmosphere states on the structure and characteristics of CdTe polycrystalline thin films made by close-spaced sublimation].

    Science.gov (United States)

    Zheng, Hua-jing; Zheng, Jia-gui; Feng, Liang-huan; Zhang, Jing-quan; Xie, Er-qing

    2005-07-01

    The structure and characteristics of CdTe thin films are dependent on the working atmosphere states in close-spaced sublimation. In the present paper, CdTe polycrystalline thin films were deposited by CSS in mixture atmosphere of argon and oxygen. The physical mechanism of CSS was analyzed, and the temperature distribution in CSS system was measured. The dependence of preliminary nucleus creation on the atmosphere states (involving component and pressure) was studied. Transparencies were measured and optic energy gaps were calculated. The results show that: (1) The CdTe films deposited in different atmospheres are cubic structure. With increasing oxygen concentration, a increases and reaches the maximum at 6% oxygen concentration, then reduces, and increases again after passing the point at 12% oxygen concentration. Among them, the sample depositing at 9% oxygen concentration is the best. The optic energy gaps are 1.50-1.51 eV for all CdTe films. (2) The samples depositing at different pressures at 9% oxygen concentration are all cubical structure of CdTe, and the diffraction peaks of CdS and SnO2:F still appear. With the gas pressure increasing, the crystal size of CdTe minishes, the transparency of the thin film goes down, and the absorption side shifts to the short-wave direction. (3) The polycrystalline thin films with high quality deposit in 4 minutes under the depositing condition that the substrate temperature is 550 degrees C, and source temperature is 620 degrees C at 9% oxygen concentration. PMID:16241058

  16. Characteristics of an atmospheric-pressure line plasma excited by 2.45 GHz microwave travelling wave

    Science.gov (United States)

    Suzuki, Haruka; Nakano, Suguru; Itoh, Hitoshi; Sekine, Makoto; Hori, Masaru; Toyoda, Hirotaka

    2016-01-01

    An atmospheric-pressure line plasma was produced by microwave discharge using a slot antenna with travelling microwave power. Two different types of plasma mode, i.e., “pseudo” and “real” line plasma were investigated using a high-speed camera under different discharge conditions, such as slot gap width and power. Using wide slot gaps (0.5 mm) and low powers (microwave power, the plasma mode changed from the pseudo to real line plasma mode, i.e., the spatiotemporally uniform plasma mode along the slot. A gas temperature was obtained from N2 second positive band spectra as low as 400 K. The movement of the plasma in the pseudo line plasma mode was well explained by a one-dimensional diffusion model including the spatial distribution of the ionization rate in a moving plasma.

  17. Comparison of ice particle characteristics simulated by the Community Atmosphere Model (CAM5 with in-situ observations

    Directory of Open Access Journals (Sweden)

    T. Eidhammer

    2014-03-01

    Full Text Available Detailed measurements of ice crystals in cirrus clouds were used to compare with results from the Community Atmospheric Model Version 5 (CAM5 global climate model. The observations are from two different field campaigns with contrasting conditions: Atmospheric Radiation Measurements Spring Cloud Intensive Operational Period in 2000 (ARM-IOP, which was characterized primarily by midlatitude frontal clouds and cirrus, and Tropical Composition, Cloud and Climate Coupling (TC4, which was dominated by anvil cirrus. Results show that the model typically overestimates the slope parameter of the exponential size distributions of cloud ice and snow, while the variation with temperature (height is comparable. The model also overestimates the ice/snow number concentration (0th moment of the size distribution and underestimates higher moments (2nd through 5th, but compares well with observations for the 1st moment. Overall the model shows better agreement with observations for TC4 than for ARM-IOP in regards to the moments. The mass-weighted terminal fallspeed is lower in the model compared to observations for both ARM-IOP and TC4, which is partly due to the overestimation of the size distribution slope parameter. Sensitivity tests with modification of the threshold size for cloud ice to snow autoconversion (Dcs do not show noticeable improvement in modeled moments, slope parameter and mass weighed fallspeed compared to observations. Further, there is considerable sensitivity of the cloud radiative forcing to Dcs, consistent with previous studies, but no value of Dcs improves modeled cloud radiative forcing compared to measurements. Since the autoconversion of cloud ice to snow using the threshold size Dcs has little physical basis, future improvement to combine cloud ice and snow into a single category, eliminating the need for autoconversion, is suggested.

  18. Exploring atmospheric boundary layer characteristics in a severe SO2 episode in the north-eastern Adriatic

    Directory of Open Access Journals (Sweden)

    Z. B. Klaić

    2009-07-01

    Full Text Available Stable atmospheric conditions are often connected with the occurrence of high pollution episodes especially in urban or industrial areas. In this work we investigate a severe SO2 episode observed on 3–5 February 2002 in a coastal industrial town of Rijeka, Croatia, where very high daily mean concentrations (up to 353.5 μg m−3 were measured. The episode occurred under high air pressure conditions, which were accompanied with a fog and low wind speeds. Three air quality models (50-km EMEP model, 10-km EMEP4HR model and 1-km CAMx model were used to simulate SO2 concentrations fields and to evaluate the relative contribution of distant and local pollution sources to observed concentrations. Results suggest that the episode was caused predominately by local sources. Furthermore, using three-dimensional, higher-order turbulence closure mesoscale meteorological model (WRF, the wind regimes and thermo-dynamical structure of the lower troposphere above the greater Rijeka area (GRA were examined in detail. Modelled atmospheric fields suggest several factors whose simultaneous acting was responsible for elevated SO2 concentrations. Established small scale wind directions supported the transport of air from nearby industrial areas with major pollution sources towards Rijeka. This transport was associated with strong, ground-based temperature inversion and correspondingly, very low mixing layer (at most up to about 140 m. Additionally, the surface winds in Rijeka were light or almost calm thus, preventing ventilation of polluted air. Finally, a vertical circulation cell formed between the mainland and a nearby island, supported the air subsidence and the increase of static stability.

  19. Millimeter-wave imaging radiometer for cloud, precipitation and atmospheric water vapor studies

    Science.gov (United States)

    Racette, P. E.; Dod, L. R.; Shiue, J. C.; Adler, R. F.; Jackson, D. M.; Gasiewski, A. J.; Zacharias, D. S.

    1992-01-01

    A millimeter-wave imaging radiometer (MIR) developed by NASA Goddard Space Flight Center is described. The MIR is a nine-channel total power radiometer developed for atmospheric research. Three dual-pass band channels are centered about the strongly opaque 183-GHz water vapor absorption line; the frequencies are 183 +/- 1, +/- 3, and +/- 7 GHz. Another channel is located on the wing of this band at 150 GHz. These four channels have varying degrees of opacity from which the water vapor profile can be inferred. The design and salient characteristics of this instrument are discussed, together with its expected benefits.

  20. A comparison of 4 MeV Proton and Co-60 gamma irradiation induced degradation in the electrical characteristics of N-channel MOSFETs

    Science.gov (United States)

    Anjum, Arshiya; Vinayakprasanna, N. H.; Pradeep, T. M.; Pushpa, N.; Krishna, J. B. M.; Gnana Prakash, A. P.

    2016-07-01

    N-channel depletion MOSFETs were irradiated with 4 MeV Proton and Co-60 gamma radiation in the dose range of 100 krad(Si) to 100 Mrad(Si). The electrical characteristics of MOSFET such as threshold voltage (Vth), density of interface trapped charges (ΔNit), density of oxide trapped charges (ΔNot), transconductance (gm), mobility (μ), leakage current (IL) and drain saturation current (ID Sat) were studied as a function of dose. A considerable increase in ΔNit and ΔNot and decrease in Vth,gm, μ, and ID Sat was observed after irradiation. The results of 4 MeV Proton irradiation were compared with that of Co-60 gamma radiation and it is found that the degradation is more for the devices irradiated with 4 MeV Protons when compared with the Co-60 gamma radiation. This indicates that Protons induce more trapped charges in the field oxide region when compared to the gamma radiation.

  1. Characteristics of size-fractionated atmospheric metals and water-soluble metals in two typical episodes in Beijing

    Science.gov (United States)

    Wang, Qingqing; Ma, Yongliang; Tan, Jihua; Zheng, Naijia; Duan, Jingchun; Sun, Yele; He, Kebin; Zhang, Yuanxun

    2015-10-01

    The abundance and behaviour of metals and water-soluble metals (V, Cr, Mn, Fe, Cu, Zn, As, Sr, Ag, Cd, Sn, Sb, Ba and Pb) in size-fractionated aerosols were investigated during two typical episodes in Beijing. Water-soluble inorganic ions (Na+, K+, Mg2+, Ca2+, NH4+ , F-, Cl-, SO4 2 - and NO3-) were also measured. Atmospheric metals and water-soluble metals were both found at high levels; for PM2.5, average As, Cr, Cd, Cu, Mn and Pb concentrations were 14.8, 203.3, 2.5, 18.5, 42.6 and 135.3 ng/m3, respectively, and their water-soluble components were 11.1, 1.7, 2.4, 14.5, 19.8 and 97.8 ng/m3, respectively. Daily concentrations of atmospheric metals and water-soluble metals were generally in accordance with particle mass. The highest concentrations of metals and water-soluble metals were generally located in coarse mode and droplet mode, respectively. The lowest mass of metals and water-soluble metals was mostly in Aitken mode. The water solubility of all metals was low in Aitken and coarse modes, indicating that freshly emitted metals have low solubility. Metal water solubility generally increased with the decrease in particle size in the range of 0.26-10 μm. The water solubility of metals for PM10 was: 50% ≤ Cd, As, Sb, Pb; 26% water-soluble metals and their water solubility increased when polluted air mass came from the near west, near north-west, south-west and south-east of the mainland, and decreased when clean air mass came from the far north-west and far due south. The influence of dust-storms and clean days on water-soluble metals and size distribution was significant; however, the influence of rainfall was negligible. Aerosols with high concentrations of SO4 2 - , K+ and NH4+ might indicate increased potential for human health effects because of their high correlation with water-soluble metals. Industrial emissions contribute substantially to water-soluble metal pollution as water-soluble metals show higher correlation with Cd, Sn, Sb and Pb that are

  2. Physicochemical and oxidative characteristics of semi-volatile components of quasi-ultrafine particles in an urban atmosphere

    Science.gov (United States)

    Verma, Vishal; Pakbin, Payam; Cheung, Ka Lam; Cho, Arthur K.; Schauer, James J.; Shafer, Martin M.; Kleinman, Michael T.; Sioutas, Constantinos

    2011-02-01

    This study examines the physicochemical and redox profiles of atmospheric semi-volatile compounds to evaluate their contribution to the oxidative potential of ambient particulate matter (PM). Concentrated ambient and thermodenuded quasi-ultrafine particles (dithiothreitol) assay. Detailed chemical analyses of PM samples, including organic and elemental carbon, water soluble elements, inorganic ions and PAHs (polycyclic aromatic hydrocarbons), were conducted to quantify the volatility profiles of different PM species, and also to investigate their effect on measured oxidative potential. Refractory constituents, such as metals and elemental carbon, were marginally affected by heating, while labile species such as organic carbon and PAHs showed progressive loss in concentration with increase in TD temperature. The DTT-measured oxidative potential of PM was significantly decreased as the aerosols were heated and their semi-volatile components were progressively removed (42 ± 5%, 47 ± 8% and 66 ± 6% decrease at 50, 100 and 200 °C, respectively). Thus, semi-volatile compounds present in quasi-ultrafine urban aerosols constitute a significant fraction of PM oxidative potential, which is associated with the cellular generation of reactive oxygen species. Regression analysis performed between chemical constituents and DTT activity showed that the oxidative potential was strongly correlated with organic carbon and PAHs ( R ≥ 0.80; p ≤ 0.05).

  3. RELATION BETWEEN SUMMER TYPHOON FREQUENCY ANOMALIES IN WEST PACIFIC AND ENSO EVENTS AND THE ANOMALOUS ATMOSPHERIC CIRCULATION CHARACTERISTICS

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xue-ming; WEI Ying-zhi; WU Chen-feng

    2006-01-01

    By using data of serially numbered typhoons in northwestern Pacific and NOAA OLR data and NCEP/NCAR reanalysis data of wind field, based on the statistics and study of the relationship between the calendar years with more (or fewer) summer typhoons and ENSO events, we compared the composites of OLR eigenvectors and tropical summer wind fields during El Ni(n)o and La Ni(n)o events with more or fewer than normal summer typhoons, respectively. The results show that, in summer, without remarkable systematic anomalies of Mascarene High and Australia High in South Hemisphere, the anomaly of Walker circulation will dominate and follow the rule of ENSO impacts to atmospheric circulation and typhoon frequency. Otherwise,when systematic anomalies of Australia High appear during the El Ni(n)o events, circulation anomalies in the South Hemisphere will dominate, and many more typhoons will occur. In 1999, which is a special year of La Ni(n)a events, northward and eastward monsoon was induced by the stronger Mascarene High, and fewer typhoons arose. The typhoon source are regions where weak vertical wind shear, warm pool in western Pacific and the area with monsoon troughs are overlapping with each other. Finally, this paper analyzes and compares the source locations and ranges of more (fewer) typhoons in the events of El Ni(n)o and La Ni(n)o, respectively.

  4. Characteristics and mechanisms of the sudden warming events in the nocturnal atmospheric boundary layer: A case study using WRF

    Science.gov (United States)

    Ma, Yuanyuan; Yang, Yi; Hu, Xiao-Ming; Gan, Ruhui

    2015-10-01

    Although sudden nocturnal warming events near the earth's surface in Australia and the United States have been examined in previous studies, similar events observed occasionally over the Loess Plateau of Northwest China have not yet been investigated. The factors that lead to these warming events in such areas with their unique topography and climate remain not clear. To understand the formation mechanisms and associated thermal and dynamical features, a nocturnal warming event recorded in Gansu Province (northwest of the Loess Plateau) in June 2007 was investigated by using observations and model simulations with the Weather Research and Forecasting (WRF) model. Observations showed that this near-surface warming event lasted for 4 h and the temperature increased by 2.5°C. During this event, a decrease in humidity occurred simultaneously with the increase of temperature. The model simulation showed that the nocturnal warming was caused mainly by the transport of warmer and drier air aloft downward to the surface through enhanced vertical mixing. Wind shear played an important role in inducing the elevated vertical mixing, and it was enhanced by the continuous development of the atmospheric baroclinicity, which converted more potential energy to kinetic energy.

  5. Characteristics of Atmospheric Heat Sources over Asia in Summer:Comparison of Results Calculated Using Multiple Reanalysis Datasets

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bo; CHEN Longxun; HE Jinhai; ZHU Congwen; LI Wei

    2009-01-01

    Using 1979-2000 daily NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data (version 1, hereafter referred to as NCEP1; version 2, hereafter referred to as NCEP2), ECMWF (European Center for Medium-range Weather Forecasts) reanalysis data (ERA), and the Global Asian Monsoon Experiment (GAME) reanalysis data in summer 1998, the vertically integrated heat source (Q1) in summer is calculated, and results obtained using different datasets are com-pared. The distributions of (Q1) calculated by using NCEP1 are in good agreement with rainfall observations over the Arabian Sea/Indian Peninsula, the Bay of Bengal (BOB), and East China. The distributions of (Q1)revealed by using NCEP2 are unrealistic in the southern Indian Peninsula, the BOB, and the South China Sea. Using ERA, the heat sources over the tropical Asia are in accordance with the summer precipitation,however, the distributions of (Q1) in East China are unreasonable. In the tropical region, the distributions of the summer heat source given by NCEP1 and ERA seem to be more accurate than those revealed by NCEP2. The NCEP1 and NCEP2 data are better for calculating heat sources over the subtropical and eastern regions of mainland China.

  6. The effect of YBa2Cu3O7-x powder characteristics on thick coatings prepared by atmospheric plasma spraying

    International Nuclear Information System (INIS)

    The development of superconducting YBa2Cu3O7-x plasma sprayed coatings on metal substrates can be very useful for applications such as targets for thin-film deposition techniques (sputtering, laser ablation, ion assisted deposition) or magnetic shielding, due to the brittle nature of bulk superconductors. The plasma spraying technique is very flexible and can be used for manufacturing components with a large variety of geometries. This technique requires the use of powders with good rheological characteristics. In this study, YBa2Cu3O7-x powders were produced by using the conventional solid-state reaction route and also by spray drying a solution of nitrate precursors. Both powders, as well as mixtures of them, were plasma sprayed to develop coatings on stainless-steel substrates, with the aim of studying the effect of the feedstock powder characteristics on the coating properties. It was found that by optimizing the plasma spraying conditions, good quality coatings could be obtained. However, the powder morphology and homogeneity significantly affect the coating quality. More homogeneous powders lead to better results, the spray-dried powder being the best because of its enhanced rheological properties and good morphology. (author)

  7. Development of a nanosecond pulsed HV atmospheric pressure plasma source: preliminary assessment of its electrical characteristics and degree of thermal nonequilibrium

    International Nuclear Information System (INIS)

    This paper discusses the development and characteristics of a distributed nanosecond-pulsed glow-like discharge plasma in air at atmospheric pressure. The produced pulse is of 6.4 kV with duration at half maximum of less than 80 ns, and an average pulse repetition frequency of 150 Hz. The discharge operates in air in a concentric electrode configuration. Spectroscopic studies are presented in order to assess the thermal characteristics of the plasma as well as its spatial characteristics. Electrical diagnostics are presented along with time averaged ICCD imaging of the radially distributed plasma. Although variations occur, it is found that the plasma has uniform vibrational and rotational temperatures across the inter electrode gap illustrating a high degree of disequilibrium in the plasma. Band head intensity analysis proves the existence of a negative glow in the near cathode region. Finally, the sensitivity of individual vibrational bands to vibrational and rotational temperatures is presented as a means to most accurately evaluate the uncertainty of spectrally determined temperatures. (paper)

  8. Atmospheric attenuation characteristics of terahertz pulse propagation%太赫兹脉冲大气传输衰减特性

    Institute of Scientific and Technical Information of China (English)

    王玉文; 董志伟; 李瀚宇; 房艳燕

    2015-01-01

    THz atmospheric transmission is an important part of science and technology,which has permeated into almost all applications of terahertz technology. Research on terahertz atmospheric transmission is nearly on horizontal level in the existing literature. A dispersion attenuation model of terahertz atmospheric transmission is presented based on the radiation transfer, dispersion theory and Van-Vleck Weisskopf line-shape combined with Jet Propulsion Laboratory(JPL) database. The absorbing attenuation characteristics of terahertz atmospheric transmission along the slant path between 0.1 THz and 1 THz are studied using this model and compared with the existing literature. The influences of water vapor with different densities on the amplitude, phase and spectrum of the transient terahertz pulse are analyzed. Three relatively stable atmospheric transmission windows in 0.14 THz-0.17 THz,0.19 THz-0.32 THz and 0.32 THz-0.37 THz are obtained. This work has provided a theoretical reference for terahertz time-domain communications and space transmission.%太赫兹大气传输是太赫兹科学技术及其应用的重要组成部分,渗透于所有的太赫兹应用技术领域。研究基于辐射传输、色散理论和 Van-Vleck Weisskopf线型,结合喷气推进实验室(JPL)数据库,建立了太赫兹脉冲大气传输衰减与色散模型,对0.1 THz~1 THz频段太赫兹辐射在水汽中的吸收衰减特性进行了数值模拟研究,与现有的文献数据进行了比对。通过计算太赫兹脉冲大气传输,分析不同水汽密度和传输距离对波形幅值、相位及频谱特性的影响,得到了3个比较稳定的太赫兹脉冲大气传输窗口0.14 THz~0.17 THz、0.19 THz~0.32 THz和0.32 THz~0.37 THz,为太赫兹通信和时域太赫兹空间传输提供了理论参考。

  9. Coastal Maintained Channels in US waters

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This layer shows coastal channels and waterways that are maintained and surveyed by the U.S. Army Corps of Engineers (USACE). These channels are necessary...

  10. Research and precisely characterize the seismic reflection characteristics of channel deposition%河道沉积的地震反射特征与精确刻画研究

    Institute of Scientific and Technical Information of China (English)

    李雷涛

    2015-01-01

    准确刻画河道的空间展布是浅层气勘探研究的前提.因此,将由河道沉积的地质背景、测井曲线特征确定的地震反射特征作为"种子点",通过三维地震数据体上的河道形态自动追踪得出河道沉积的空间展布规律.再依据钻井解释的河道沉积厚度修正其空间形态,提高了河道形态的刻画精度.%Characterize the spatial distribution of the river is a prerequisite for shallow gas exploration and research. By the geologic background,the characteristics of logging curves to determine the seismic reflection characteristics of channel deposition as"seed points,"spatial distribution through the channel morphology of 3-D seismic data of the automatic tracking that channel deposition. According to channel deposition thickness drilling interpretation to amend its space form,improve the accuracy of channel morphology characterization.

  11. Characteristics of SiOX thin films deposited by atmospheric pressure chemical vapor deposition using a double-discharge system

    International Nuclear Information System (INIS)

    SiOX thin films were deposited using a gas mixture of hexamethyldisilazane (HMDS)/O2/He/Ar from a remote-type dielectric barrier discharges (DBD) source, with/without the additional direct-type DBD just above the substrate (double discharge), and the effect of the double discharge on the characteristics of the SiOX thin film was investigated. The increase of HMDS flow rate and the decrease of oxygen flow rate in the gas mixture increased the SiOX-thin-film deposition rate. The improvement of the mechanical properties for SiOX film, in addition to the increase of deposition rate, is believed to be related not only to the higher gas dissociation because of the higher power deposition but also to the lesser recombination of oxygen atoms and dissociated HMDS due to the shorter diffusion length to the substrate.

  12. 矩形截面螺旋通道内弹状流的流动特性%Flow characteristics of slug flow in helical rectangular channel

    Institute of Scientific and Technical Information of China (English)

    刘献飞; 夏国栋; 杨光

    2014-01-01

    Experimental investigations on slug flow were carried out in horizontal helical rectangular channel by using high speed flow visualization. Evolution of slug in the whole helical rectangular channel was presented and the fine features of slug flow in different positions were illustrated. The slug characteristics changed along the axial direction due to the combined effects of gravitational and centrifugal force. Based on the experimental data, slug velocity, slug frequency and length distribution in different positions were given. The present topography measurement illustrated the evolution features of liquid film thickness, which was determined by the effect of centrifugal force and gravity. Liquid film falling velocity decreased as the slug moved upward and was visibly increasing in the downward flow.%对水平放置矩形截面螺旋通道内弹状流的流动特性进行了实验研究。通过实验获得了不同周角下的气弹演变过程和局部流动特征,结果表明,其流动特性会随着螺旋周角位置的变化而变化。根据实验数据分析发现,同一工况下,不同转角气弹的运动速度、频率和长度分布不尽相同。重力和离心力的相对大小决定着内外壁面液膜的厚度,给出了同一条件下,不同时刻的液膜厚度的演变过程。最后对下降液膜的运动速度展开了分析研究,在螺旋上升过程中,液膜下降速度逐渐减小,在螺旋下降段,液膜速度明显增大。

  13. Effects of modified atmosphere, associated with masterpack transport packaging, and refrigerated storage time on the quality characteristics of pork loin cuts

    Directory of Open Access Journals (Sweden)

    Alessandra F. Rosa

    2013-10-01

    Full Text Available The objective of this research was to study the effects of modified atmosphere, associated with masterpack transport packaging, and refrigerated storage time on the quality characteristics of pork loin cuts. Cuts of pork loin were packaged in trays, covered with poly(vinyl chloride film. The trays were placed in a masterpack (MP, containing three gas compositions:  A 75% O2 : 25% CO2, B 50% O2 : 50% CO2 or C 100% CO2, and stored at 2 °C. Samples were taken after 1, 8, 15, and 22 days of storage, and evaluated for numerous shelf life traits. The development of Psychrotrophic aerobic bacteria and Pseudomonas spp. was found from the 15th day of storage. There was a significant treatment effect for some of the considered parameters, such as pH (P < 0.05 and color [L* (P < 0.07, a* (P < 0.07 and b* (P < 0.01]. There was a significant interaction (P < 0.01 for the TBARS values. It can be concluded, from the microbiological point of view, that the use of modified atmospheres containing 25% to 100% CO2 promotes the conservation of meat for up to 15 days of storage under refrigeration. From the point of view of color, atmospheres containing 75% O2 : 25% CO2 and 50% O2 : 50% CO2 ensure the color of packaged pork meat when stored at 2 °C for up to 15 days. From the point of view of lipid oxidation, packages with 100% CO2 are recommended for storage periods of more than 15 days, whereas those with 75% O2 : 25% CO2 are recommended for storage periods of up to 8 days.

  14. Pre-dose TL characteristics of quartz inclusions removed from bricks exposed to fallout radiation from atmospheric testing at the Nevada test site

    International Nuclear Information System (INIS)

    The pre-dose thermoluminescence (TL) technique is currently the most sensitive method of radiation dosimetry for direct measurement of absorbed dose to environmental materials. The technique was recently used with other TL methods in a multinational collaborative effort to measure radiation doses of less than 1 Gy in bricks and tiles from Hiroshima and Nagasaki (Maruyama et al., 1987; Haskell et al., 1987). We report here the application of the technique to the measurement of cumulative doses to bricks exposed to radiation from fallout from atmospheric testing at the Nevada Test Site during the 1950s and 1960s. Those doses, which include the components from natural background radiation, averaged less than 0.20 Gy. We describe the pre-dose characteristics of the quartz inclusions studied. (author)

  15. Investigation of deposition characteristics and properties of high-rate deposited silicon nitride films prepared by atmospheric pressure plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Silicon nitride (SiN x) films have been prepared at extremely high deposition rates by the atmospheric pressure plasma chemical vapor deposition (AP-PCVD) technique on Si(001) wafers from gas mixtures containing He, H2, SiH4 and N2 or NH3. A 150 MHz very high frequency (VHF) power supply was used to generate high-density radicals in the atmospheric pressure plasma. Deposition rate, composition and morphology of the SiN x films prepared with various deposition parameters were studied by scanning electron microscopy and Auger electron spectroscopy. Fourier transformation infrared (FTIR) absorption spectroscopy was also used to characterize the structure and the chemical bonding configurations of the films. Furthermore, etching rate with buffered hydrofluoric acid (BHF) solution, refractive index and capacitance-voltage (C-V) characteristics were measured to evaluate the dielectric properties of the films. It was found that effective passivation of dangling bonds and elimination of excessive hydrogen atoms at the film-growing surface seemed to be the most important factor to form SiN x film with a dense Si-N network. The C-V curve of the optimized film showed good interface properties, although further improvement was necessary for use in the industrial metal-insulator-semiconductor (MIS) applications

  16. CHARACTERISTICS OF ATMOSPHERIC HEAT SOURCE ASSOCIATED WITH THE SUMMER MONSOON ONSET OVER THE SOUTH CHINA SEA AND THE POSSIBLE MECHANISM RESPONSIBLE FOR ITS LATE OR EARLY ONSET

    Institute of Scientific and Technical Information of China (English)

    蓝光东; 温之平; 贺海晏

    2004-01-01

    The characteristics of atmospheric heat source associated with the summer monsoon onset in the South China Sea (SCS) are studied using ECMWF reanalysis data from 1979 to 1993. A criterion of the SCS summer monsoon onset is defined by the atmospheric heat source. Applying this criterion to the 15-year (1979 - 1993) mean field, the onset of the SCS summer monsoon is found to occur in the fourth pentad of May. And this criterion can also give reasonable results for the onset time of the SCS summer monsoon on a year-to-year basis. In addition, pretty high correlation has been found between the onset time of the SCS summer monsoon and the zonal mean vertically integrated heat source at 40(S in April. The causes for the late or early onset of the SCS summer monsoon and the close relationship between the onset time and the zonal mean vertically integrated heat source at 40 (S in April might be explained by the variations in intensity of the Hadley circulation.

  17. Threshold gas 32-channel Cherenkov counter of the spectrometer EXCHARM

    International Nuclear Information System (INIS)

    The Cherenkov 32-channel threshold gas counter with 420-cm air radiator at the atmospheric pressure is described. Spherical mirrors with the curvature radius of 214 cm and photomultipliers FEU-125, FEU-49B were used in the counter for collection and registration of the Cherenkov radiation. The photomultipliers inlet windows are covered with films of spectra mixers. The efficiency of charged particles registration on the plateau of threshold characteristics (β ≥ 0.99984) exceeds 97%. 6 refs., 6 figs., 1 tab

  18. Spatio-temporal Variations of Phytoplankton and Bio-optical Characteristics In Case Ii Waters: Example of The Eastern English Channel During Spring 2000

    Science.gov (United States)

    Vantrepotte, V.; Brunet, C.; Mériaux, X.; Lécuyer, E.; Vellucci, V.

    In the aim to use remote sensing technique to estimate algal biomass concentrations in surface coastal waters, it is necessary to obtain in situ information on the mesoscale phytoplankton dynamics, as well as on bio-optical properties of water masses. This step is useful to regionally validate and interpret the satellite-derived data and for lo- cal primary production modelisation. Five mesoscale cruises (BiopTel cruises) were realized in the eastern English Channel between February and October 2000, in order to study phytoplankton dynamics and bio-optical characteristics, as well as the factors controlling their seasonal variations. From the measurements realized at two depths in the water column (phytoplankton pigments by HPLC, nutrient concentrations, phyto- plankton productivity by Phyto-Pam technique, yellow substance concentrations, phy- toplankton absorption spectrum), we can define several biological provinces and their temporal succession. Fv/Fm ratio and ETR measurements (as a proxy for primary productivity) show variations according to space (different ecosystems and coastal- offshore transects) and time (season) in relation with phytoplankton quantity and quality, light and nutrient availability. Significant mesoscale relationships are found between ETR and some hydrobiological parameters. Moreover, spatio-temporal vari- ations of IOPs are highlighted. Yellow substances present their higher concentrations near the Seine and the Somme estuaries, and follow a seasonal variation characterized by two phases. From winter to early spring, they decrease in relation with the decrease of rivers runoff and then they significantly increase from early spring to summer, in relation with the increase of water temperature. Phytoplankton absorption spectrum results show a high variability in space and time, and these results are discussed in relationship with phytoplankton community composition and physiological state. Re- gional relationships between bio

  19. Different characteristics of char and soot in the atmosphere and their ratio as an indicator for source identification in Xi'an, China

    Directory of Open Access Journals (Sweden)

    Y. M. Han

    2010-01-01

    Full Text Available Numerous definitions and analytical techniques for elemental (or black carbon (EC have been published in the scientific literature, but still no generally accepted interdisciplinary definition exists. EC is not a single chemical compound, but is mainly composed of two parts of carbon contents: combustion residues from pyrolysis and combustion emissions formed via gas-to-particle conversion. Accordingly EC is subdivided into two classes: char and soot. Char is defined as carbonaceous materials obtained by heating organic substances and formed directly from pyrolysis, or as an impure form of graphitic carbon obtained as a residue when carbonaceous material is partially burned or heated with limited access of air. Soot is defined as only those carbon particles that form at high temperature via gas-phase processes. Since the different classes of EC have different chemical and physical properties, their optical light-absorbing properties differ, so that it is essential to differentiate them in the environment. The thermal optical reflectance (TOR method was used to differentiate between char-EC and soot-EC according to its stepwise thermal evolutional oxidation of different carbon fractions under different temperatures and atmosphere. Char-EC and soot-EC are operationally defined as EC1-OP and EC2+EC3 (EC1, EC2 and EC3 corresponding to carbon fractions evolved at 550, 700 and 800 °C in a 98% He/2% O2 atmosphere, respectively, respectively. One year of observations of the daily and seasonal variations of carbonaceous particles were conducted in Xi'an, China in 2004 to demonstrate the different characteristics of char and soot in the atmosphere. Total carbon (TC, organic carbon (OC, EC and char-EC showed similar seasonal trends, with high concentrations in winter and low concentrations in summer, while soot-EC revealed relatively small seasonal variations, with maximum concentration (1.85±0.72 μg m−3 in spring and minimum

  20. HIGH-RESOLUTION LABORATORY SPECTRA OF THE λ193 CHANNEL OF THE ATMOSPHERIC IMAGING ASSEMBLY INSTRUMENT ON BOARD SOLAR DYNAMICS OBSERVATORY

    International Nuclear Information System (INIS)

    Extreme ultraviolet spectra of C, O, F, Ne, S, Ar, Fe, and Ni have been excited in an electron beam ion trap and studied with much higher resolution than available on the Solar Dynamics Observatory (SDO) in order to ascertain the spectral composition of the SDO/Atmospheric Imaging Assembly (AIA) observations. We present our findings in the wavelength range 182-200 Å, which, overall, corroborate the working models of how to interpret the SDO/AIA data. We find, however, that the inclusion of a number of additional lines might improve the data interpretation

  1. The Performance Improvement of N2 Plasma Treatment on ZrO2 Gate Dielectric Thin-Film Transistors with Atmospheric Pressure Plasma-Enhanced Chemical Vapor Deposition IGZO Channel.

    Science.gov (United States)

    Wu, Chien-Hung; Huang, Bo-Wen; Chang, Kow-Ming; Wang, Shui-Jinn; Lin, Jian-Hong; Hsu, Jui-Mei

    2016-06-01

    The aim of this paper is to illustrate the N2 plasma treatment for high-κ ZrO2 gate dielectric stack (30 nm) with indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs). Experimental results reveal that a suitable incorporation of nitrogen atoms could enhance the device performance by eliminating the oxygen vacancies and provide an amorphous surface with better surface roughness. With N2 plasma treated ZrO2 gate, IGZO channel is fabricated by atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) technique. The best performance of the AP-PECVD IGZO TFTs are obtained with 20 W-90 sec N2 plasma treatment with field-effect mobility (μ(FET)) of 22.5 cm2/V-s, subthreshold swing (SS) of 155 mV/dec, and on/off current ratio (I(on)/I(off)) of 1.49 x 10(7). PMID:27427669

  2. Effects of picosecond terawatt UV laser beam filamentation and a repetitive pulse train on creation of prolonged plasma channels in atmospheric air

    International Nuclear Information System (INIS)

    Amplitude-modulated UV laser pulse of up to 30 J energy was produced at hybrid Ti:Sapphire/KrF GARPUN-MTW laser facility when a preliminary amplified train of short pulses was injected into unstable resonator cavity of the main e-beam-pumped KrF amplifier. The combined radiation consisted of regeneratively amplified picosecond pulses with subTW peak power overlapped with 100-ns pulse of a free-running lasing. The advantages of combined radiation for production of long-lived prolonged plasma channels in air and HV discharge triggering were demonstrated: photocurrent sustained by modulated pulse is two orders of magnitude higher and HV breakdown distance is twice longer than for a smooth UV pulse. It was found that in contrast to IR radiation multiple filamentation of high-power UV laser beam does not produce extended nonlinear focusing of UV radiation

  3. RFI channels

    Science.gov (United States)

    Mceliece, R. J.

    1980-01-01

    A class of channel models is presented which exhibit varying burst error severity much like channels encountered in practice. An information-theoretic analysis of these channel models is made, and conclusions are drawn that may aid in the design of coded communication systems for realistic noisy channels.

  4. Gating a channel photomultiplier with a fast high-voltage switch: reduction of afterpulse rates in a laser-induced fluorescence instrument for measurement of atmospheric OH radical concentrations.

    Science.gov (United States)

    Kanaya, Yugo; Akimoto, Hajime

    2006-02-20

    By employing a commercially available high-voltage switch in a time-gating circuit to drive a channel photomultiplier (CPM), the afterpulse rates are significantly reduced in the time window to collect fluorescence >200 ns after the pulsed laser excitation. The CPM, kept deactivated under normal conditions (normally off), is turned on immediately after the passage of the laser pulse by shifting the voltage applied to the photocathode by 150 V to collect the fluorescence. When the detection system is used as part of a laser-induced fluorescence instrument to measure atmospheric OH radicals with the photon-counting method, the background signal is reduced by more than a factor of 10 as compared with our previous case where a conventional dynode-gated photomultiplier tube (PMT) is used, while the sensitivity toward the fluorescence is almost unchanged. A detection limit as low as 2 x 10(5) radicals cm-3 or 0.008 parts per trillion by volume is achieved for OH, with an integration time of 1 min and a signal-to-noise ratio of 2, enabling sensitive detection of the important radical in the atmosphere. This system is a superior choice with higher sensitivity and cost effectiveness as compared with the gated PMITs utilizing a microchannel plate as an electron multiplier, and could also be used effectively in light detection and ranging (lidar) instruments, where a delayed scattering signal would be efficiently discriminated from afterpulses. PMID:16523790

  5. Effects of flow rate of atmosphere gases on the characteristics of Zn-doped ITO (ZITO) thin films for organic light emitting diodes

    Science.gov (United States)

    Jeong, Hwa-Kyun; Lee, Kyu-Mann

    2015-12-01

    We have investigated the effect of ambient gases on the structural, electrical, and optical characteristics of Zn-doped indium tin oxide (ZITO) thin films intended for use as anode contacts in organic light emitting diodes (OLED) devices. These ZITO thin films are deposited by radio frequency (RF) magnetron sputtering under different ambient gases (Ar, Ar + O2 and Ar + H2) at 300°C. In order to investigate the influences of the oxygen and hydrogen, the flow rate of oxygen and hydrogen in argon mixing gas has been changed from 0.1 sccm to 0.5 sccm and from 0.1 sccm to 1 sccm, respectively. The intensity of the (400) peak in the ZITO thin films increases with increasing H2 flow rate whilst the (400) peak was nearly invisible in an atmosphere of Ar + O2. The electrical resistivity of the ZITO thin films increases with increasing O2 flow rate, whereas the electrical resistivity decreases with increasing H2 flow rate. The change of electrical resistivity with changes in the ambient gas composition is mainly interpreted in terms of the charge carrier mobility and the charge carrier concentration. All the films show an average transmittance of over 80% in the visible range. The optical bandgap of the ZITO films increases with increasing H2 flow rates, whereas the optical bandgap of the ZITO films deposited in an O2 atmosphere decreases with increasing O2 flow rates. The current density and the luminance of the OLED devices with ZITO thin films deposited in 1 sccm of H2 ambient gas are the highest among all the films. The optical bandgap energy of ZITO thin films plays a major role in OLED device performance, especially the current density and luminance.

  6. Observation studies on the influence of atmospheric boundary layer characteristics associate with air quality in dry season over the Pearl River Delta, China

    Science.gov (United States)

    Fan, Shaojia; Wu, Meng; Li, Haowen; Liao, Zhiheng; Fan, Qi; Zhu, Wei

    2016-04-01

    The characteristics of atmospheric boundary layer (ABL) is the very important factors influence on air quality in dry season over the Pearl River Delta (PRD), China. Based on the sounding data at six stations (Xinken,Dongguan, Sanshui, Nanhai, Shunde, and Heshan) which obtained from three times ABL experiments carried in dry season over PRD, the influence of wind and temperature vertical structure to the air quality over PRD has been studied with wind and temperature profiles, inversion layer, recirculation factor (RF), atmospheric boundary layer height (ABLH) and ventilation index (VI). It was found that the vertical wind of PRD could be divided in typical three layers according two wind shears appeared in 800 m and 1300 m. The thickness of calm or lower wind speed layer in pollution days was 500-1000m thicker than that of clean days, and its last time also much longer than that of clean days. The frequency of surface inversion in pollution days was about 35%,the mean thickness was about 100 m. With the influence of sea breeze, the frequency and thickness of surface inversion layer at Xinken station was a little lower than that in inland. Influenced by sea-land breezes and urban heat-island circulation, the RF of pollution days in coastal and urban area was quite smaller than that of clean days. During sea-land breezes days, the pollutants would be transported back to inland in nighttime with the influence of sea breeze, and resulted in 72.7% sea-land breezes was pollution days. The evolution of ABL was very typical in PRD during dry season. In pollution days, daily ABLH in PRD was lower than 500 m, daily VI was about 500-1500 m2/s. In clean days, daily VI was much larger than 2500 m2/s. An improved conceptual model of ABL influence on poor air quality and the parameters of the ABL characteristics associate with poor air quality in dry season over PRD had been summarized.

  7. DMSP SSMT/2 - Atmospheric Water Vapor Profiler

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The SSM/T-2 sensor is a five channel, total power microwave radiometer with three channels situated symmetrically about the 183.31 GHz water vapor resonance line...

  8. Pressure-dependent calibration of the OH and HO2 channels of a FAGE HOx instrument using the Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC)

    Science.gov (United States)

    Winiberg, F. A. F.; Smith, S. C.; Bejan, I.; Brumby, C. A.; Ingham, T.; Malkin, T. L.; Orr, S. C.; Heard, D. E.; Seakins, P. W.

    2015-02-01

    The calibration of field instruments used to measure concentrations of OH and HO2 worldwide has traditionally relied on a single method utilising the photolysis of water vapour in air in a flow tube at atmospheric pressure. Here the calibration of two FAGE (fluorescence assay by gaseous expansion) apparatuses designed for HOx (OH and HO2) measurements have been investigated as a function of external pressure using two different laser systems. The conventional method of generating known concentrations of HOx from H2O vapour photolysis in a turbulent flow tube impinging just outside the FAGE sample inlet has been used to study instrument sensitivity as a function of internal fluorescence cell pressure (1.8-3.8 mbar). An increase in the calibration constants CHO and CHO2 with pressure was observed, and an empirical linear regression of the data was used to describe the trends, with ΔCHO = (17 ± 11) % and ΔCHO2 = (31.6 ± 4.4)% increase per millibar air (uncertainties quoted to 2σ). Presented here are the first direct measurements of the FAGE calibration constants as a function of external pressure (440-1000 mbar) in a controlled environment using the University of Leeds HIRAC chamber (Highly Instrumented Reactor for Atmospheric Chemistry). Two methods were used: the temporal decay of hydrocarbons for calibration of OH, and the kinetics of the second-order recombination of HO2 for HO2 calibrations. Over comparable conditions for the FAGE cell, the two alternative methods are in good agreement with the conventional method, with the average ratio of calibration factors (conventional : alternative) across the entire pressure range, COH(conv)/COH(alt) = 1.19 ± 0.26 and CHO2(conv)/CHO2(alt) = 0.96 ± 0.18 (2σ). These alternative calibration methods currently have comparable systematic uncertainties to the conventional method: ~ 28% and ~ 41% for the alternative OH and HO2 calibration methods respectively compared to 35% for the H2O vapour photolysis method; ways in

  9. Purification of the small mechanosensitive channel of Escherichia coli (MscS): the subunit structure, conduction, and gating characteristics in liposomes

    Science.gov (United States)

    Sukharev, Sergei

    2002-01-01

    The small mechanosensitive channel, MscS, is a part of the turgor-driven solute efflux system that protects bacteria from lysis in the event of osmotic downshift. It has been identified in Escherichia coli as a product of the orphan yggB gene, now called mscS (Levina et al., 1999, EMBO J. 18:1730). Here I show that that the isolated 31-kDa MscS protein is sufficient to form a functional mechanosensitive channel gated directly by tension in the lipid bilayer. MscS-6His complexes purified in the presence of octylglucoside and lipids migrate in a high-resolution gel-filtration column as particles of approximately 200 kDa. Consistent with that, the protein cross-linking patterns predict a hexamer. The channel reconstituted in soybean asolectin liposomes was activated by pressures of 20-60 mm Hg and displayed the same asymmetric I-V curve and slight anionic preference as in situ. At the same time, the single-channel conductance is proportional to the buffer conductivity in a wide range of salt concentrations. The rate of channel activation in response to increasing pressure gradient across the patch was slower than the rate of closure in response to decreasing steps of pressure gradient. Therefore, the open probability curves were recorded with descending series of pressures. Determination of the curvature of patches by video imaging permitted measurements of the channel activity as a function of membrane tension (gamma). Po(gamma) curves had the midpoint at 5.5 +/- 0.1 dyne/cm and gave estimates for the energy of opening DeltaG = 11.4 +/- 0.5 kT, and the transition-related area change DeltaA = 8.4 +/- 0.4 nm(2) when fitted with a two-state Boltzmann model. The correspondence between channel properties in the native and reconstituted systems is discussed.

  10. Discharge Characteristics of an Atmospheric Pressure Argon Plasma Jet Generated with Screw Ring-Ring Electrodes in Surface Dielectric Barrier Discharge

    International Nuclear Information System (INIS)

    An atmospheric-pressure argon plasma jet with screw ring-ring electrodes in surface dielectric barrier discharge is generated by a sinusoidal excitation voltage at 8 kHz. The discharge characteristics, such as rotational and vibrational temperature of nitrogen, electronic excitation temperature, oxygen atomic density, nitrogen molecular density, and average electron density, are estimated. It is found that the rotational temperature of nitrogen is in the range of 352 ∼ 392 K by comparing the simulated spectrum with the measured spectrum at the C3Πu → B3Πg(Δv = −2) band transition, the electronic excitation temperature is found to be in the range of 3127 ∼ 3230 K by using the Boltzmann plot method, the oxygen atomic and nitrogen molecular density are of the order of magnitude of 1016 cm−3 by the actinometry method, and the average electron density is of the order of magnitude of 1012 cm−3 by the energy balance equation. Besides, the effective power, conduction, and displacement current are measured during the discharge. (low temperature plasma)

  11. The ignition delay, laminar flame speed and adiabatic temperature characteristics of n-pentane, n-hexane and n-heptane under O{sub 2}/CO{sub 2} atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Ran [Huazhong Univ. of Science and Technology, Wuhan (China). State Key Lab. of Coal Combustion; Wuhan Textile Univ. (China). School of Environment and Urban Construction; Liu, Hao; Zhong, Xiaojiao; Wang, Zijian; Jin, Ziqin; Qiu, Jianrong [Huazhong Univ. of Science and Technology, Wuhan (China). State Key Lab. of Coal Combustion; Chen, Yingming [Wuhan Textile Univ. (China). School of Environment and Urban Construction

    2013-07-01

    Oxy-fuel (O{sub 2}/CO{sub 2}) combustion is one of the several promising new technologies which can realize the integrated control of CO{sub 2}, SO{sub 2}, NO{sub X} and other pollutants. However, when fuels are burned in the high CO{sub 2} concentration environment, the combustion characteristics can be very different from conventional air-fired combustion. Such changes imply that the high CO{sub 2} concentration atmosphere has impacts on the combustion processes. In this paper, the ignition time, laminar flame speed and adiabatic temperature property of C{sub 5} {proportional_to} C{sub 7} n-alkane fuels were studied under both ordinary air atmosphere and O{sub 2}/CO{sub 2} atmospheres over a wide range of CO{sub 2} concentration in the combustion systems. A new unified detailed chemical kinetic model was validated and used to simulate the three liquid hydrocarbon fuel's flame characteristics. Based on the verified model, the influences of various parameters (atmosphere, excess oxygen ratio, O{sub 2} concentration, CO{sub 2} concentration, and alkane type) on the C{sub 5} {proportional_to} C{sub 7} n-alkane's flame characteristics were systematically investigated. It can be concluded that high CO{sub 2} concentration atmosphere has negative effect on n-pentane, n-hexane and n-heptane flame's ignition, laminar flame speed and adiabatic temperature. Besides, this work confirms that high CO{sub 2} concentration atmosphere's chemical effects play a pronounced role on the flame characteristics, especially for the ignition time property.

  12. Atmospheric Neutrino Status

    CERN Document Server

    O'Sullivan, E

    2016-01-01

    This conference proceeding discusses new results arising from atmospheric neutrino detection in the Super-Kamiokande and IceCube experiments. Super-Kamiokande has measured atmospheric neutrinos in the energy range of 100 MeV-10 TeV and uses this data set to conclusively measure the east-west effect to 8.0 (6.0) $\\sigma$ for electron (muon) neutrinos. IceCube is ideal for measuring high energy atmospheric neutrinos and has explored how different production channels for atmospheric neutrinos contribute to the total overall observed flux. The measurement is consistent with the conventional spectrum, produced by the decay of pions and kaon, while the contribution from the prompt channel (due to charm decay) is consistent with zero.

  13. Distribution of atmospheric reactive nitrogen at two sites of different socio- economic characteristics in IndoGangetic Plain(IGP) region, India.

    Science.gov (United States)

    Singh, S.; Sharma, A.; Kulshrestha, U. C.

    2015-12-01

    In India, most of the human population lives in rural areas. People depends on agriculture products to meet the demand of food supply. In order to get higher yield of agriculture and food product, increased practice of fertilizer application has added extra burden of nutrients especially, the reactive nitrogen (Nr) species viz NH3 and NOx. Growing energy demands has resulted in increased emissions of NOx from coal combustion in thermal power plant and the petroleum combustion in transport sector. In addition, biomass burning in traditional cooking and heating has become significant source of NH3 and NOx in Indian region. Significance of the study lies in the fact that increasing Nr emissions have adverse impact on human health, plant, soil and water bodies directly and to see the effect, knowledge of emission and deposition for Nr at different sites. Hence, the selection of the sites for present study was done very carefully. Delhi city and Mai village were selected to represent typical characteristics of high and low socioeconomic region respectively. Delhi is the capital of India, known for higher income group urban cluster where rural site having agricultural dominance has its importance in Indian scenario because still in India our primary source of income is agriculture. Atmospheric abundance of two major gaseous inorganic (Nr) species i.e NH3 and NO2 has been measured for one year, on monthly basis. Average concentrations of NH3 at urban and rural site have been recorded as 40.4 ±16.8 and 51.57 ±22.8 μg/m3 respectively. The average concentrations of NO2 have been recorded as 24.4 ±13.5 and 18.8 ± 12.6 μg/m3 at urban & rural site respectively. Study, also presents seasonal and diurnal variations of gaseous reactive nitrogen species at urban & rural sites to observe the contribution of different the sources of atmospheric Nr. Dynamics of Nr at both sites will be discussed in details at the conference.

  14. Low-voltage back-gated atmospheric pressure chemical vapor deposition based graphene-striped channel transistor with high-κ dielectric showing room-temperature mobility > 11,000 cm(2)/V·s.

    Science.gov (United States)

    Smith, Casey; Qaisi, Ramy; Liu, Zhihong; Yu, Qingkai; Hussain, Muhammad Mustafa

    2013-07-23

    Utilization of graphene may help realize innovative low-power replacements for III-V materials based high electron mobility transistors while extending operational frequencies closer to the THz regime for superior wireless communications, imaging, and other novel applications. Device architectures explored to date suffer a fundamental performance roadblock due to lack of compatible deposition techniques for nanometer-scale dielectrics required to efficiently modulate graphene transconductance (gm) while maintaining low gate capacitance-voltage product (CgsVgs). Here we show integration of a scaled (10 nm) high-κ gate dielectric aluminum oxide (Al2O3) with an atmospheric pressure chemical vapor deposition (APCVD)-derived graphene channel composed of multiple 0.25 μm stripes to repeatedly realize room-temperature mobility of 11,000 cm(2)/V·s or higher. This high performance is attributed to the APCVD graphene growth quality, excellent interfacial properties of the gate dielectric, conductivity enhancement in the graphene stripes due to low tox/Wgraphene ratio, and scaled high-κ dielectric gate modulation of carrier density allowing full actuation of the device with only ±1 V applied bias. The superior drive current and conductance at Vdd = 1 V compared to other top-gated devices requiring undesirable seed (such as aluminum and poly vinyl alcohol)-assisted dielectric deposition, bottom gate devices requiring excessive gate voltage for actuation, or monolithic (nonstriped) channels suggest that this facile transistor structure provides critical insight toward future device design and process integration to maximize CVD-based graphene transistor performance. PMID:23777434

  15. Low-voltage back-gated atmospheric pressure chemical vapor deposition based graphene-striped channel transistor with high-κ dielectric showing room-temperature mobility > 11 000 cm2/V·s

    KAUST Repository

    Smith, Casey

    2013-07-23

    Utilization of graphene may help realize innovative low-power replacements for III-V materials based high electron mobility transistors while extending operational frequencies closer to the THz regime for superior wireless communications, imaging, and other novel applications. Device architectures explored to date suffer a fundamental performance roadblock due to lack of compatible deposition techniques for nanometer-scale dielectrics required to efficiently modulate graphene transconductance (gm) while maintaining low gate capacitance-voltage product (CgsVgs). Here we show integration of a scaled (10 nm) high-κ gate dielectric aluminum oxide (Al2O3) with an atmospheric pressure chemical vapor deposition (APCVD)-derived graphene channel composed of multiple 0.25 μm stripes to repeatedly realize room-temperature mobility of 11 000 cm 2/V·s or higher. This high performance is attributed to the APCVD graphene growth quality, excellent interfacial properties of the gate dielectric, conductivity enhancement in the graphene stripes due to low t ox/Wgraphene ratio, and scaled high-κ dielectric gate modulation of carrier density allowing full actuation of the device with only ±1 V applied bias. The superior drive current and conductance at Vdd = 1 V compared to other top-gated devices requiring undesirable seed (such as aluminum and poly vinyl alcohol)-assisted dielectric deposition, bottom gate devices requiring excessive gate voltage for actuation, or monolithic (nonstriped) channels suggest that this facile transistor structure provides critical insight toward future device design and process integration to maximize CVD-based graphene transistor performance. © 2013 American Chemical Society.

  16. Effect of front guide nozzle shape on the flow characteristics in an augmentation channel of a direct drive turbine for wave power generation

    Institute of Scientific and Technical Information of China (English)

    Deepak; PRASAD; Mohammed; Asid; ZULLAH; Mohammed; Rafiuddin; AHMED; Young-Ho; LEE

    2010-01-01

    There is an increasing interest in cross flow turbines(also known as Banki turbines) for small and low head applications because of their simple structure as well as low capital and maintenance costs.The present work aims at implementing the direct drive turbine(DDT) of cross flow type for wave power generation.A numerical wave tank was used to simulate the waves and after obtaining the desired wave properties;the augmentation channel plus the front guide nozzle and rear chamber were integrated to the numerical wave tank.The waves in the numerical wave tank were generated by a piston type wave maker which was located at the wave tank inlet.The inlet which was modeled as a plate wall moved sinusoidally with the general function x = asinω t.The augmentation channel consisted of a front nozzle,rear nozzle and an internal fluid region which represented the turbine housing.The front and rear nozzles were geometrically the same.Three different front guide nozzle configurations were studied:a standard guide nozzle which was originally attached to the augmentation channel and two other front guide nozzles of different geometries.The purpose of this study is to observe how the front guide nozzle shape influences the flow downstream,mainly in the augmenta-tion channel,water power and the first stage energy conversion.The analysis was performed using a commercial CFD code ANSYS-CFX.The results of the flow in the augmentation channel for the three front guide nozzles are presented in this paper.

  17. Experimental study on the impact of HF channel characteristic parameters on communication error rate%短波信道特征参数对通信误码率影响的试验分析

    Institute of Scientific and Technical Information of China (English)

    王立夫; 孙凤娟

    2012-01-01

    介绍了一种融短波通信与电离层斜向探测于一体的联合试验平台,该平台信道探测与通信同时进行,共用一套硬件设备,克服了设备不匹配及探测信道参量失效等问题,并基于该平台实录数据提取了通信误码率及信道特征参量包括信噪比、衰落深度、衰落率、多径扩展、各模式信号幅度、群距离、主模式相位、多普勒频移及多普勒扩展等,统计分析了各信道参量对通信误码率的影响,得出了一些有意义的结论。%A test platform combined HF communication with ionospheric oblique sounding is introduced, with which the ionosphere channel sounding and communi- cation is carried out synchronously using the same hardware equipment. By this way, the problem of equipment mismatch and no real-time channel parameters could be solved. Based on the experimental data measured by this plat{orm the communication bit error ratio(BER) and the channel characteristic parameters, in- cluding signal to noise ratio (SNR), fading depth, fading rate, mulitipath spread, signal strength, group distance, the phase of major-mode, Doppler shift and Doppler spread, are extracted. The impact of the channel characteristic parameters on the communication BER is statistically analyzed. Significant conclusions are pro- posed in the end of this paper.

  18. Electrical and spectral characteristics of an atmospheric pressure argon plasma jet generated with tube-ring electrodes in surface dielectric barrier discharge

    International Nuclear Information System (INIS)

    An atmospheric-pressure argon plasma jet is generated with tube-ring electrodes in surface dielectric barrier discharge by a sinusoidal excitation voltage at 8 kHz. The electrical and spectral characteristics are estimated such as conduction and displacement current, electric-field, electron temperature, rotational temperature of N2 and OH, electronic excitation temperature, and oxygen atomic density. It is found that the electric-field magnitudes in the top area of the ground electrode are higher than that in the bottom area of the power electrode, and the electron temperature along radial direction is in the range of 9.6–10.4 eV and along axial direction in the range of 4.9–10 eV. The rotational temperature of N2 obtained by comparing the simulated spectrum with the measured spectrum at the C3Πu → B3Πg(Δv = − 2) band transition is in the range of 342–387 K, the electronic excitation temperature determined by Boltzmann's plot method is in the range of 3188–3295 K, and the oxygen atomic density estimated by the spectral intensity ratio of atomic oxygen line λ = 844.6 nm to argon line λ = 750.4 nm is in the order of magnitude of 1016 cm−3, respectively. - Highlights: ► The conduction and displacement current are calculated by equivalent circuit diagram. ► The 2D distribution of electric-field magnitude is calculated by ElecNet software. ► The electron temperature along axial direction is in the range of 4.9–10 eV. ► The oxygen atomic density is about a magnitude of 1016 cm−3

  19. Production of extended plasma channels in atmospheric air by amplitude-modulated UV radiation of GARPUN-MTW Ti : sapphire—KrF laser. Part 2. Accumulation of plasma electrons and electric discharge control

    International Nuclear Information System (INIS)

    The problem of the production of extended (∼1 m) plasma channels is studied in atmospheric air by amplitude-modulated laser pulses of UV radiation, which are a superposition of a subpicosecond USP train amplified in a regenerative KrF amplifier with an unstable confocal resonator and a quasi-stationary lasing pulse. The USPs possess a high (0.2–0.3 TW) peak power and efficiently ionise oxygen molecules due to multiphoton ionisation, and the quasi-stationary lasing pulse, which has a relatively long duration (∼100 ns), maintains the electron density at a level ne = (3–5) × 1014 cm—3 by suppressing electron attachment to oxygen. Experiments in laser triggering of high-voltage electric discharges suggest that the use of combined pulses results in a significant lowering of the breakdown threshold and enables controlling the discharge trajectory with a higher efficiency in comparison with smooth pulses. It was shown that controlled breakdowns may develop with a delay of tens of microseconds relative to the laser pulse, which is many orders of magnitude greater than the lifetime of free electrons in the laser-induced plasma. We propose a mechanism for this breakdown, which involves speeding-up of the avalanche ionisation of the air by negative molecular oxygen ions with a low electron binding energy (∼0.5 eV) and a long lifetime (∼1 ms), which are produced upon cessation of the laser pulse. (extreme light fields and their applications)

  20. Production of extended plasma channels in atmospheric air by amplitude-modulated UV radiation of GARPUN-MTW Ti : sapphire—KrF laser. Part 2. Accumulation of plasma electrons and electric discharge control

    Science.gov (United States)

    Zvorykin, V. D.; Ionin, Andrei A.; Levchenko, A. O.; Mesyats, Gennadii A.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, Igor V.; Sunchugasheva, E. S.; Ustinovskii, N. N.; Shutov, A. V.

    2013-04-01

    The problem of the production of extended (~1 m) plasma channels is studied in atmospheric air by amplitude-modulated laser pulses of UV radiation, which are a superposition of a subpicosecond USP train amplified in a regenerative KrF amplifier with an unstable confocal resonator and a quasi-stationary lasing pulse. The USPs possess a high (0.2-0.3 TW) peak power and efficiently ionise oxygen molecules due to multiphoton ionisation, and the quasi-stationary lasing pulse, which has a relatively long duration (~100 ns), maintains the electron density at a level ne = (3-5) × 1014 cm—3 by suppressing electron attachment to oxygen. Experiments in laser triggering of high-voltage electric discharges suggest that the use of combined pulses results in a significant lowering of the breakdown threshold and enables controlling the discharge trajectory with a higher efficiency in comparison with smooth pulses. It was shown that controlled breakdowns may develop with a delay of tens of microseconds relative to the laser pulse, which is many orders of magnitude greater than the lifetime of free electrons in the laser-induced plasma. We propose a mechanism for this breakdown, which involves speeding-up of the avalanche ionisation of the air by negative molecular oxygen ions with a low electron binding energy (~0.5 eV) and a long lifetime (~1 ms), which are produced upon cessation of the laser pulse.

  1. A Novel Bi-wavelength Method for Accurately Measuring Gain and Noise Characteristics of an Erbium-Doped Fibre Amplifier for Multi-Channel Wavelength Division Multiplexing Transmission

    Institute of Scientific and Technical Information of China (English)

    刘艳格; 蒙红云; 袁树忠; 田建国; 开桂云; 董孝义

    2003-01-01

    Gain and noise figure (NF) are the most important two parameters of an erbium-doped fibre amplifier (EDFA) for a multi-channel wavelength division multiplexing (WDM) transmission system. A simple bi-wavelength method for accurate gain and NF spectrum measurement of EDFA for WDM applications is proposed. A saturating input signal, whose power equals to the sum of all the WDM signal power and whose wavelength is determined by the channel numbers and the wavelength of the WDM input signals, saturates the EDFA in a degree as the same as the WDM signals input. Meanwhile, a small power probe signal scans and measures the gain and the NF value at every wavelength of the WDM input signals. Investigative results by numerical simulation show that the gain and the NF spectra measured by this method have good agreement with the real spectra of the WDM signal input in a large total input power range. The maximum errors of the gain and the NF are less than 0.2 dB and 0.16dB, respectively, for a 50-channel input case. The method is competent for the accurate gain and the NF spectrum measurement of the fibre preamplifier and the line-amplifier for WDM applications and has the advantages of simplicity, convenience and easy implement.

  2. Channel Morphology and Bed Sediment Characteristics Before and After Habitat Enhancement Activities in the Uridil Property, Platte River, Nebraska, Water Years 2005-2008

    Science.gov (United States)

    Kinzel, Paul J.

    2009-01-01

    Fluvial geomorphic data were collected by the United States Geological Survey from July 2005 to June 2008 (a time period within water years 2005 to 2008) to monitor the effects of habitat enhancement activities conducted in the Platte River Whooping Crane Maintenance Trust's Uridil Property, located along the Platte River, Nebraska. The activities involved the removal of vegetation and sand from the tops of high permanent islands and the placement of the sand into the active river channel. This strategy was intended to enhance habitat for migratory water birds by lowering the elevations of the high islands, thereby eliminating a visual obstruction for roosting birds. It was also thought that the bare sand on the lowered island surfaces could serve as potential habitat for nesting water birds. Lastly, the project supplied a local source of sediment to the river to test the hypothesis that this material could contribute to the formation of lower sandbars and potential nesting sites downstream. Topographic surveys on the islands and along river transects were used to quantify the volume of removed sand and track the storage and movement of the introduced sand downstream. Sediment samples were also collected to map the spatial distribution of river bed sediment sizes before and after the management activities. While the project lowered the elevation of high islands, observations of the sand addition indicated the relatively fine-grained sand that was placed in the active river channel was rapidly transported by the flowing water. Topographic measurements made 3 months after the sand addition along transects in the area of sediment addition showed net aggradation over measurements made in 2005. In the year following the sand addition, 2007, elevated river flows from local rain events generally were accompanied by net degradation along transects within the area of sediment addition. In the spring of 2008, a large magnitude flow event of approximately 360 cubic meters per

  3. The characteristic analysis of atmospheric mercury during haze days in Qingdao%青岛霾天气下大气汞的污染特征分析

    Institute of Scientific and Technical Information of China (English)

    张玉卿; 刘汝海; 崔雪晴; 周建平; 王艳

    2014-01-01

    2013年1月14~17日青岛市经历了一次大范围的霾污染过程,采集并测定大气气态汞和颗粒态汞,研究汞的污染特征.结果表明,气态汞(TGM)的平均浓度为(2.8±0.9)ng/m3,颗粒汞(PHg)的平均浓度为(245±174)pg/m3.在霾发生的14、15日PHg/TSP 的比值明显高于16、17日,且TGM与PHg浓度呈负相关关系,霾日气象条件有利于TGM向PHg转化.大气汞浓度与温度、相对湿度正相关,与风速负相关.TGM与SO2、NO2显著正相关,化石燃料的燃烧是大气汞的主要来源.对大气气团的后向轨迹进行聚类分析,将其分为5类,霾日大气中的汞主要来自近距离传输,受山东本地污染影响,气态汞含量最高.%In order to investigate the characteristics of atmospheric mercury pollution, total gaseous mercury (TGM) and particulate mercury (PHg) samples were collected in Qingdao during January 14-17, 2013, when a serious haze event occurred. The results showed that the average concentrations of TGM and PHg in Qingdao during this haze event were (2.8±0.9) ng/m3 and (245±174) pg/m3, respectively. On haze days (January 14 and 15), there was a negative correlation between TGM and PHg, and TGM/PHg ratios were higher than that on non-haze days (January 16 and 17), indicating that meteorological conditions would promote the transformation of TGM to PHg. Correlation analysis between mercury concentrations and environmental factors showed that both TGM and PHg were positively correlated with temperature and relative humidity, and negatively correlated with wind speed. TGM was positively correlated with SO2 and NO2, suggesting fossil fuel combustion was its major source. The pathways of air masses associated with the mercury samples were classified into 5 categories based cluster analysis. Atmospheric mercury in Qingdao during this event was mainly influenced by short-range transport, the influence of local pollution from Shandong area contributed to the highest TGM and PHg contents

  4. Polymer Surface Treatment by Atmospheric Pressure Low Temperature Surface Discharge Plasma:Its Characteristics and Comparison with Low Pressure Oxygen Plasma Treatment

    Institute of Scientific and Technical Information of China (English)

    Atsushi KUWABARA; Shin-ichi KURODA; Hitoshi KUBOTA

    2007-01-01

    The polymer treatment with a low-temperature plasma jet generated on the atmospheric pressure surface discharge (SD) plasma is performed.The change of the surface property over time,in comparison with low pressure oxygen (O2) plasma treatment,is examined.As one compares the treatment by atmospheric pressure plasma to that by the low pressure O2 plasma of PS (polystyrene) the treatment effects were almost in complete agreement.However,when the atmospheric pressure plasma was used for PP(polypropylene),it produced remarkable hydrophilic effects.

  5. Differential expression of hERG1 channel isoforms reproduces properties of native I(Kr) and modulates cardiac action potential characteristics

    DEFF Research Database (Denmark)

    Larsen, Anders Peter; Olesen, Søren-Peter

    2010-01-01

    The repolarizing cardiac rapid delayed rectifier current, I(Kr), is composed of ERG1 channels. It has been suggested that two isoforms of the ERG1 protein, ERG1a and ERG1b, both contribute to I(Kr). Marked heterogeneity in the kinetic properties of native I(Kr) has been described. We hypothesized...... that the heterogeneity of native I(Kr) can be reproduced by differential expression of ERG1a and ERG1b isoforms. Furthermore, the functional consequences of differential expression of ERG1 isoforms were explored as a potential mechanism underlying native heterogeneity of action potential duration (APD...

  6. Simulation of atmospheric transmission characteristics of laser at 1.06μm%1.06μm 激光的大气传输仿真研究

    Institute of Scientific and Technical Information of China (English)

    陈煌飞; 陈勇; 李怡勇; 王志

    2014-01-01

    To study the atmospheric transmission characteristics of laser , the laser power attenuation formula was established at a certain distance based on the general model of laser atmosphere transmission .The laser atmospheric transmittance at 1.06μm and the power onto the target were calculated with MATLAB software .Results show that the model provides the reliable theory basis for laser influencing space probe and remove of tiny pieces , and certain reference for further study about laser atmospheric attenuation characteristics .%为了研究激光的大气传输特性,基于激光大气传输的一般模型,建立了激光传播到某一距离的功率衰减公式。采用定性定量的方法,利用MATLAB软件对模型进行仿真计算,分析了1.06μm激光大气传输的大气透过率以及到靶功率。结果表明,该模型对激光干扰空间探测器、清除微小碎片等提供了可靠的理论依据。这对于深入研究激光的大气衰减特性有一定参考价值。

  7. Principal characteristics of the atmospheric changes associated to the eruption of the Nevado del Ruiz volcano and dispersion of the emitted material on November 13, 1985

    International Nuclear Information System (INIS)

    With reference to the eruption of the Nevado del Ruiz volcano on November 13, 1985, is analyzed the temporal changes of the atmospheric elements on surface and altitude. This works show the minimum sunshine value (0.0 hour/day); the temperature of the events moment decrease 10 Celsius degrade and the middle temperature to 4.5 Celsius degrade. Also is analyzed the dispersion of the piroclastic material and gases into the atmosphere

  8. Improved cosmic ray ionization model for the system lower ionosphere-middle atmosphere. Determination of approximation energy interval characteristics for the particle penetration

    Science.gov (United States)

    Velinov, Peter; Mateev, Lachezar

    The effects of galactic and solar cosmic rays (CRs) in the middle atmosphere are considered in this work. We take into account the CR modulation by solar wind and the anomalous CR component also. In fact, CRs determine the electric conductivity in the middle atmosphere and influence the electric processes in it in this way. CRs introduce solar variability in the terrestrial atmosphere and ozonosphere -because they are modulated by solar wind. A new analytical approach for CR ionization by protons and nuclei with charge Z in the lower ionosphere and the middle atmosphere is developed in this paper. For this purpose, the ionization losses (dE/dh) for the energetic charged particles according to the Bohr-Bethe-Bloch formula are approximated in three different energy intervals. More accurate expressions for CR energy decrease E(h) and electron production rate profiles q(h) are derived. The obtained formulas allow comparatively easy computer programming. q(h) is determined by the solution of a 3D integral with account of geomagnetic cut-off rigidity. The integrand in q(h) gives the possibility for application of adequate numerical methods -in this case Gauss quadrature and Romberg extrapolation, for the solution of the mathematical problem. Computations for CR ionization in the middle atmosphere are made. The contributions of the different approximation energy intervals are presented. In this way the process of interaction of CR particles with the upper and middle atmosphere are described much more realistically. The full CR composition is taken into account: protons, helium (alpha-particles), light L, medium M, heavy H and very heavy VH group of nuclei. The computations are made for different geomagnetic cut-off rigidities R in the altitude interval 35-120 km. The COSPAR International Reference Atmosphere CIRA'86 is applied in the computer program for the neutral density and scale height values. The proposed improved CR ionization model will contribute to the

  9. Characteristics of a micro-mechanical thermal flow sensor based on a two hot wires principle with constant temperature operation in a small channel

    International Nuclear Information System (INIS)

    A thermal mass flow sensor with high dynamic flow range in silicon bulk micromachining membrane technology is presented. The response behavior of this sensor based on a two hot wire principle is described. This sensor configuration uses two hot wires mounted closely spaced one behind the other within a thin membrane, kept at the same temperature. The power to compensate cooling of and the interaction between the two hot wires are used to calculate mass flows and directionality of flows of gaseous and liquid fluids in a small channel. The response shows both anemometric and calorimetric behavior, depending on fluid, channel height and flow range. The hot wires are heated relative to temperature sensors located also on an isolated membrane on the same chip. Choosing an appropriate evaluation procedure an independence of the signal from the ambient temperature is achieved. This configuration will be discussed in view of the published results of single heater flow sensors, being of calorimetric or anemometric type. A calculation method for the determination of linear and power law range of the response is given. (paper)

  10. Characteristics of a micro-mechanical thermal flow sensor based on a two hot wires principle with constant temperature operation in a small channel

    Science.gov (United States)

    Lange, P.; Weiss, M.; Warnat, S.

    2014-12-01

    A thermal mass flow sensor with high dynamic flow range in silicon bulk micromachining membrane technology is presented. The response behavior of this sensor based on a two hot wire principle is described. This sensor configuration uses two hot wires mounted closely spaced one behind the other within a thin membrane, kept at the same temperature. The power to compensate cooling of and the interaction between the two hot wires are used to calculate mass flows and directionality of flows of gaseous and liquid fluids in a small channel. The response shows both anemometric and calorimetric behavior, depending on fluid, channel height and flow range. The hot wires are heated relative to temperature sensors located also on an isolated membrane on the same chip. Choosing an appropriate evaluation procedure an independence of the signal from the ambient temperature is achieved. This configuration will be discussed in view of the published results of single heater flow sensors, being of calorimetric or anemometric type. A calculation method for the determination of linear and power law range of the response is given.

  11. Metro Multnomah Wetlands - Multnomah Channel Wetland Restoration Monitoring Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Multnomah Channel Wetland Restoration Monitoring Project characterizes wetlands use by juvenile salmonids and other fishes in the Multnomah Channel Marsh...

  12. Coastal Maintained Channels in US waters as of May 2013

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This layer shows coastal channels and waterways that are maintained and surveyed by the U.S. Army Corps of Engineers (USACE). These channels are necessary...

  13. Heat transfer characteristics of Fe{sub 3}O{sub 4} ferrofluid flowing in a mini channel under constant and alternating magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemian, M.; Najafian Ashrafi, Z., E-mail: z_najafian@ut.ac.ir; Goharkhah, M.; Ashjaee, M.

    2015-05-01

    Laminar forced convection heat transfer of water based Fe{sub 3}O{sub 4} ferrofluid in a mini channel in the presence of constant and alternating magnetic fields is studied numerically. The hot ferrofluid flows into the 20 mm (l)×2 mm (h) mini channel with isothermal top and bottom cold surfaces and is subjected to a transverse non-uniform magnetic field produced by current carrying wires. Two-phase mixture model is implemented and the governing equations are solved using the finite volume approach. Primarily, the effects of the constant magnetic field location and intensity on the convective heat transfer are investigated. Simulation results show that the heat transfer is enhanced due to the disruption of the thermal boundary layer. However, this effect is more pronounced when the magnetic field source is placed in the fully developed region. In the next section, an alternating magnetic field with frequencies ranging from 0 to 10 Hz is imposed to the ferrofluid at different Reynolds numbers of Re=10, 25 and 50. A 16.48% heat transfer enhancement is obtained with a constant magnetic field at Re=25 and magnetic field intensity, Mn=1.07×10{sup 8}. This value is increased up to 27.72% by applying an alternating magnetic field with the same intensity at f=4 Hz. Results also indicate that the heat transfer enhancement due to the magnetic field is more significant at lower Reynolds numbers. The optimum frequency for heat transfer enhancement has been obtained for all the cases which shows that it has an increasing trend with the Reynolds number. - Highlights: • Ferrofluid forced convection heat transfer in a mini channel under constant and alternating magnetic fields is investigated numerically. • Heat transfer depends on Reynolds number, magnetic field location, intensity and frequency. • Heat transfer is enhanced noticeably campared to the case with no magnetic field. Enhancement is more significant when the magnetic field is placed in the fully developed

  14. The characteristics of the discharge channel at the switching stage in different types of dielectrics taking into account the chemical composition of the initial dielectric

    International Nuclear Information System (INIS)

    The switch is one of the most important elements in the powerful high voltage equipment, because just it i.e. its switching time defines the minimum possible pulse front duration at the load. The most important time responses of a switch are switching time, discharge delay time, standard deviation from given discharge delay time. For the spark gaps these responses are defined by the breakdown stages of their working dielectrics and by the parameters of the discharge circuit. The physical pattern for the process of conditions shaping for the initiation of switching and natural switching in the high-voltage circuits by spark dischargers using dielectrics of different types as a working medium has been given. The most proper way for the calculation of the switching process is the solution of closed equations set describing this process on the basis of differential equation (or equations) of discharge circuit and that of energy balance within the discharge channels

  15. Geometric pumping in autophoretic channels

    CERN Document Server

    Michelin, Sebastien; De Canio, Gabriele; Lobato-Dauzier, Nicolas; Lauga, Eric

    2015-01-01

    Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory.

  16. Performance analysis of LDPC codes on OOK terahertz wireless channels

    Science.gov (United States)

    Chun, Liu; Chang, Wang; Jun-Cheng, Cao

    2016-02-01

    Atmospheric absorption, scattering, and scintillation are the major causes to deteriorate the transmission quality of terahertz (THz) wireless communications. An error control coding scheme based on low density parity check (LDPC) codes with soft decision decoding algorithm is proposed to improve the bit-error-rate (BER) performance of an on-off keying (OOK) modulated THz signal through atmospheric channel. The THz wave propagation characteristics and channel model in atmosphere is set up. Numerical simulations validate the great performance of LDPC codes against the atmospheric fading and demonstrate the huge potential in future ultra-high speed beyond Gbps THz communications. Project supported by the National Key Basic Research Program of China (Grant No. 2014CB339803), the National High Technology Research and Development Program of China (Grant No. 2011AA010205), the National Natural Science Foundation of China (Grant Nos. 61131006, 61321492, and 61204135), the Major National Development Project of Scientific Instrument and Equipment (Grant No. 2011YQ150021), the National Science and Technology Major Project (Grant No. 2011ZX02707), the International Collaboration and Innovation Program on High Mobility Materials Engineering of the Chinese Academy of Sciences, and the Shanghai Municipal Commission of Science and Technology (Grant No. 14530711300).

  17. Threshold gas 32-channel Cherenkov counter of the EXCHARM spectrometer

    International Nuclear Information System (INIS)

    A 32-channel threshold gas Cherenkov counter with 420 cm air radiator at atmospheric pressure is described. Spherical mirrors with curvature radius of 214 cm and FEU-125, FEU-49B photomultipliers are used in the counter for collection and detection of the Cherenkov radiation. The input windows of the photomultipliers are coated with a shifter of the light spectrum. The detection efficiency of charged particles at a plateau of the threshold characteristic (β ≥ 0,99984) exceeds 97%. The counter is a part of the identification system of the EXCHARM spectrometer. 6 refs., 6 figs., 1 tab

  18. On the marine atmospheric boundary layer characteristics over Bay of Bengal and Arabian Sea during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB)

    Indian Academy of Sciences (India)

    Denny P Alappattu; D Bala Subrahamanyam; P K Kunhikrishnan; K M Somayaji; G S Bhat; R Venkatesan; C B S Dutt; A Bagavath Singh; V K Soni; A S Tripathi

    2008-07-01

    Detailed measurements were carried out in the Marine Atmospheric Boundary Layer (MABL) during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) which covered both Arabian Sea and Bay of Bengal during March to May 2006. In this paper, we present the meteorological observations made during this campaign. The latitudinal variation of the surface layer turbulent fluxes is also described in detail.

  19. DIFFUSION IN THE VICINITY OF STANDARD-DESIGN NUCLEAR POWER PLANTS-I. WIND-TUNNEL EVALUATION OF DIFFUSIVE CHARACTERISTICS OF A SIMULATED SUBURBAN NEUTRAL ATMOSPHERIC BOUNDARY LAYER

    Science.gov (United States)

    A large meteorological wind tunnel was used to simulate a suburban atmospheric boundary layer. The model-prototype scale was 1:300 and the roughness length was approximately 1.0 m full scale. The model boundary layer simulated full scale dispersion from ground-level and elevated ...

  20. Channel Islands, Kelp Forest Monitoring, Sea Temperature

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset from the Channel Islands National Park's Kelp Forest Monitoring Program has subtidal temperature data taken at permanent monitoring sites. Since 1993,...

  1. Simulation study of communication link for Pioneer Saturn/Uranus atmospheric entry probe. [signal acquisition by candidate modem for radio link

    Science.gov (United States)

    Hinrichs, C. A.

    1974-01-01

    A digital simulation is presented for a candidate modem in a modeled atmospheric scintillation environment with Doppler, Doppler rate, and signal attenuation typical of the radio link conditions for an outer planets atmospheric entry probe. The results indicate that the signal acquisition characteristics and the channel error rate are acceptable for the system requirements of the radio link. The simulation also outputs data for calculating other error statistics and a quantized symbol stream from which error correction decoding can be analyzed.

  2. Non-stoichiometory and vaporization characteristic of Li{sub 2.1}TiO{sub 3.05} in hydrogen atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Tsuyoshi [Blanket Irradiation and Analysis Group, Directorates of Fusion Energy Research, Japan Atomic Energy Agency, 4002 Narita-cho, Oarai-machi, Higashi Ibaraki-gun, Ibaraki 311-1393 (Japan)], E-mail: hoshino.tsuyoshi@jaea.go.jp; Yasumoto, Masaru [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Tsuchiya, Kunihiko; Hayashi, Kimio [Blanket Irradiation and Analysis Group, Directorates of Fusion Energy Research, Japan Atomic Energy Agency, 4002 Narita-cho, Oarai-machi, Higashi Ibaraki-gun, Ibaraki 311-1393 (Japan); Nishimura, Hidetoshi; Suzuki, Akihiro [Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata-Shirane, Ibaraki 319-1188 (Japan); Terai, Takayuki [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2007-10-15

    Lithium titanate (Li{sub 2}TiO{sub 3}) is one of the most promising candidates among the proposed solid breeder materials in fusion reactors because of its chemical satiability. Addition of H{sub 2} to inert sweep gas has been proposed for enhancing the release of bred tritium from breeder material. However, the mass of Li{sub 2}TiO{sub 3} has been found to decrease with time in the hydrogen atmosphere. In order to control the mass change at the time of high-temperature use, development of Li{sub 2}TiO{sub 3} which has excess Li{sub 2}O is needed. Li{sub 2}TiO{sub 3} (L100) and Li{sub 2.1}TiO{sub 3.05} (L105) were prepared by solid-state reaction at 1273 K of Li{sub 2}CO{sub 3} and TiO{sub 2} powders. In thermogravimetry, the masses of samples L100 and L105 were found to decrease with time in a hydrogen atmosphere, then to increase after a change of the atmosphere from hydrogen to oxygen. Sample L105 has fewer oxygen defects than L100. An atmosphere-controlled high-temperature mass spectrometer has provided the vapor pressure data for L100 and L105, under the conditions of D{sub 2} atmospheres. Sample L105 has a higher partial pressure of total Li-containing species than L100 above 1093 K.

  3. Atmospheric contamination

    International Nuclear Information System (INIS)

    It is about the levels of contamination in center America, the population's perception on the problem, effects of the atmospheric contamination, effects in the environment, causes of the atmospheric contamination, possibilities to reduce the atmospheric contamination and list of Roeco Swisscontac in atmospheric contamination

  4. The impact of non-uniform channel layer growth on device characteristics in state of the Art Si/SiGe/Si p-metal oxide semiconductor field effect transistors

    International Nuclear Information System (INIS)

    In this study we have highlighted the effect of non-uniform channel layer growth by the direct correlation of the microstructure and electrical characteristics in state-of-the-art pseudomorphic Si/SiGe p-channel metal oxide semiconductor field effect transistor devices fabricated on Si. Two nominally identical sets of devices from adjacent locations of the same wafer were found to have radically different distributions in gate threshold voltages. Due to the close proximity and narrow gate length of the devices, focused ion beam milling was used to prepare a number of thin cross-sections from each of the two regions for subsequent analysis using transmission electron microscopy. It was found that devices from the region giving a very narrow range of gate threshold voltages exhibited a uniform microstructure in general agreement with the intended growth parameters. However, in the second region, which showed a large spread in the gate threshold voltages, profound anomalies in the microstructure were observed. These anomalies consisted of fluctuations in the quality and thickness of the SiGe strained layers. The non-uniform growth of the strained SiGe layer clearly accounted for the poorly controlled threshold voltages of these devices. The results emphasize the importance of good layer growth uniformity to ensure optimum device yield

  5. Dynamic Characteristics Analysis of Double-channel Aqueduct with FEM in the South-to-North Water Diversion Project%南水北调双槽渡槽结构动力特性有限元分析

    Institute of Scientific and Technical Information of China (English)

    徐建国; 张威; 王博; 陈淮

    2011-01-01

    In order to study dynamic characteristics of the large-scale double-channel aqueduct, the spatial finite clement analysis model of the Laozhangzhuang aqueduct in middle route of the South-ro-North Water Diversion Project is established with software SAP2000. The modal analysis method is applied to calculate the frequency and modal of the first 12 steps for two cases, which includes conditions of design depth of three meters and without water. The whole process and the results achieve the desired effect. which provides reference basis for the large-scale double-channel aqueduct seismic analysis.%为研究大型双槽渡槽的动力特性,采用通用有限元软件SAP2000对南水北调中线工程中的老张庄渡槽整体结构建立空间有限元分析模型,采用模态分析方法分析计算了渡槽墩体前12阶的自振频率与振动模态,得到了渡槽在3 m设计水深和无水2种工况下的振动特性,整个过程和结果均达到了预期效果,为大型双槽渡槽结构的抗震分析提供了参考依据.

  6. Simulate the volcanic radiation features in medium wave infrared channels

    Science.gov (United States)

    Gong, Cailan; Jiang, Shan; Liu, Fengyi; Hu, Yong

    2015-10-01

    There are different scales and intensities of the volcanic eruption in the world every year. Existing medium wave infrared (MWI) remote sensing channels are often at atmospheric window in 3-5μm, lack of water vapor and carbon dioxide(CO2) absorption channels data, such as 2.2μm, 2.7μm and so on, however the 2.7μm absorption bands can be used as volcanoes, forest fires and other hot target identification. In order to obtain the high-temperature targets (HTT)radiation features, such as volcanic eruptions and forest fires in the water vapor absorption channels, Firstly, the HTT should be identified from the existing bands based on the temperature differences between the objects and the surrounding environment. Then, the HTT radiation features were simulated, and the correlation between the radiations of different bands were established with statistical analysis method. The HTT reorganization from remote sensing data, radiation characteristics simulation in different atmospheric models were described, then the bands transformed models were set up. The volcanic HTT radiation characteristics were simulated in wavelength 2.7μm and 4.433-4.498μm (band 24 of MODIS) based on the known bands of 3.55 -3.93μm (band 3 of FengYun-3 Visible and Infrared Scanning Radiometer (VIRR)). The simulated results were tested by the volcanic HTT radiation characteristics with 4.433-4.498μm by known bands of MODIS image and the simulated 4.433-4.498μm image. The causes of errors generated were analyzed. The study methods were useful to the new remote sensor bands imaging characteristics simulation analysis.

  7. Relation between the occurrence of burnout and differential-pressure fluctuation characteristics caused by the disturbance waves passing by a flow obstacle in a vertical boiling two-phase upward flow in a narrow annular channel

    International Nuclear Information System (INIS)

    If a flow obstacle such as a spacer is set in a boiling two-phase flow within an annular channel, where the inner tube is used as a heater, the temperature on the surface of the heater tube is severely affected by the existence of the spacer. In some case the spacer has a cooling effect, and in the other case it causes the dryout of the cooling liquid film on the heating surface resulting in the burnout of the tube. The burnout mechanism near the spacer, however, is not still clear. In the present paper we focus our attention on the occurrence of the burnout near a spacer, and discuss the occurrence location of dryout and burnout and the relation between the occurrence of burnout and differential-pressure fluctuation characteristics caused by the disturbance waves passing by a spacer. (author)

  8. Comparison of the characteristics of atmospheric pressure plasma jets using different working gases and applications to plasma-cancer cell interactions

    Directory of Open Access Journals (Sweden)

    Hea Min Joh

    2013-09-01

    Full Text Available Atmospheric pressure plasma jets employing nitrogen, helium, or argon gases driven by low-frequency (several tens of kilohertz ac voltage and pulsed dc voltage were fabricated and characterized. The changes in discharge current, optical emission intensities from reactive radicals, gas temperature, and plume length of plasma jets with the control parameters were measured and compared. The control parameters include applied voltage, working gas, and gas flow rate. As an application to plasma-cancer cell interactions, the effects of atmospheric pressure plasma jet on the morphology and intracellular reactive oxygen species (ROS level of human lung adenocarcinoma cell (A549 and human bladder cancer cell (EJ were explored. The experimental results show that the plasma can effectively control the intracellular concentrations of ROS. Although there exist slight differences in the production of ROS, helium, argon, or nitrogen plasma jets are found to be useful in enhancing the intracellular ROS concentrations in cancer cells.

  9. Comparison of the characteristics of atmospheric pressure plasma jets using different working gases and applications to plasma-cancer cell interactions

    OpenAIRE

    Hea Min Joh; Sun Ja Kim; Chung, T. H.; Leem, S H

    2013-01-01

    Atmospheric pressure plasma jets employing nitrogen, helium, or argon gases driven by low-frequency (several tens of kilohertz) ac voltage and pulsed dc voltage were fabricated and characterized. The changes in discharge current, optical emission intensities from reactive radicals, gas temperature, and plume length of plasma jets with the control parameters were measured and compared. The control parameters include applied voltage, working gas, and gas flow rate. As an application to plasma-c...

  10. Radio propagation measurement and channel modelling

    CERN Document Server

    Salous, Sana

    2013-01-01

    While there are numerous books describing modern wireless communication systems that contain overviews of radio propagation and radio channel modelling, there are none that contain detailed information on the design, implementation and calibration of radio channel measurement equipment, the planning of experiments and the in depth analysis of measured data. The book would begin with an explanation of the fundamentals of radio wave propagation and progress through a series of topics, including the measurement of radio channel characteristics, radio channel sounders, measurement strategies

  11. Study of turbine with side channel runner

    OpenAIRE

    Jandourek, Pavel

    2012-01-01

    This thesis deals with proposal of constructional solving turbine with side channel. Basis for the design is lossy characteristics of the valve. The intention is to replace hydraulic closures by turbine with side channel runner. Hydraulic losses in the flow restriction in turn replaced by the electricity generation in the comparable characteristics of valve and turbine.

  12. Formation of plasma channels in air under filamentation of focused ultrashort laser pulses

    Science.gov (United States)

    Ionin, A. A.; Seleznev, L. V.; Sunchugasheva, E. S.

    2015-03-01

    The formation of plasma channels in air under filamentation of focused ultrashort laser pulses was experimentally and theoretically studied together with theoreticians of the Moscow State University and the Institute of Atmospheric Optics. The influence of various characteristics of ultrashort laser pulses on these plasma channels is discussed. Plasma channels formed under filamentation of focused laser beams with a wavefront distorted by spherical aberration (introduced by adaptive optics) and by astigmatism, with cross-section spatially formed by various diaphragms and with different UV and IR wavelengths, were experimentally and numerically studied. The influence of plasma channels created by a filament of a focused UV or IR femtosecond laser pulse (λ = 248 nm or 740 nm) on characteristics of other plasma channels formed by a femtosecond pulse at the same wavelength following the first one with varied nanosecond time delay was also experimentally studied. An application of plasma channels formed due to the filamentation of focused UV ultrashort laser pulses including a train of such pulses and a combination of ultrashort and long (~100 ns) laser pulses for triggering and guiding long (~1 m) electric discharges is discussed.

  13. Atmospheric muons: experimental aspects

    CERN Document Server

    Cecchini, Stefano

    2012-01-01

    We present a review of atmospheric muon flux and energy spectrum measurements over almost six decades of muon momentum. Sea-level and underground/water/ice experiments are considered. Possible sources of systematic errors in the measurements are examinated. The characteristics of underground/water muons (muons in bundle, lateral distribution, energy spectrum) are discussed. The connection between the atmospheric muon and neutrino measurements are also reported.

  14. Research of the discharge with parameters of lightning channel

    International Nuclear Information System (INIS)

    The experiments were taken place in the High Voltage Laboratory at the Institute of Plasma Physics and Laser Microfusion in Warsaw. We investigated the parameters of discharge (200 A, 60 C) at atmospheric pressure. The visible spectroscopy and high-speed cameras as the main diagnostic tools were used. During the discharge current channel transformations and ball-like structures formation were observed. Lifetime of this balls increases with its diameter. In visible spectra a lot of lines belonging copper none ionized atoms were present. We also found several lines that represent Cu II and Cu III emission and a few lines of O I, O II and N I, N II. The plasma temperature and density was calculated assuming the local thermal equilibrium. The records of high-speed cameras were used to determinate the diameter and evolution of plasma channel and to calculate the characteristic speed of plasma transformation. Acquired data provided both to make confrontation of pressures in the plasma and to observe the creation of ball structures. From this comparison we may deduce that the atmospheric pressure plays the main role. Magnetic pressure controls the dynamics of the channel in relatively long scales of ms. (author)

  15. 青藏高原大气水分循环特征%Characteristics of the water cycle in the atmosphere over the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    徐祥德; 赵天良; Lu Chungu; 施晓晖

    2014-01-01

    Tibetan Plateau in building Asian summer monsoon system,regional and global water cycles,the advances in study of the atmospheric water cycle over the Tibetan Plat¯ eau are reviewed with the emphases on the respects of (1)the local convection in the atmosphere over the Tibetan Plateau,(2) the mechanism of the two¯ladder"CISK"in the vapor uplift to the Tibetan Plateau,(3)the structures of apparent heat source over the Tibetan Plateau with the multi¯scale vapor busway,(4)the patterns of source¯receptor of vapor from oceans to the plateau,(5)the cross¯hemispheric water cycle in the vertical atmospheric circulation and (6)a comprehensive understanding of the atmospheric water cycle over the Tibetan Plateau.In the recent research,a comprehensive pattern of the atmospheric water cycle over the Tibetan Plateau is revealed;the mechanism on the thermal forcing of large Tibetan Plateau¯topography and its effect on cloud¯precipitation are investigated;the Asian regional and cross¯hemispheric vapor transport structures in the vertical atmospheric circulation driven by the Tibetan Plateau forcing are characterized;and the feedback interaction between the Tibet¯ an Plateau`s thermal forcing and the hydrological process of ocean¯atmosphere¯land is explored.The Asian rivers originating from the Tibetan Plateau have been sustaining the life,agricultural and industrial water usage for the Asian regions with a large population,and therefore,it is vital to understand the atmospheric water cycle and its impact on the changes in the Tibetan Plateau water resource under background of the global warming.The atmospheric water cycle process over the TP with the global effect is needed to further studied.

  16. Inter-comparison of Seasonal Variation, Chemical Characteristics, and Source Identification of Atmospheric Fine Particles on Both Sides of the Taiwan Strait

    OpenAIRE

    Tsung-Chang Li; Chung-Shin Yuan; Hu-Ching Huang; Chon-Lin Lee; Shui-Ping Wu; Chuan Tong

    2016-01-01

    The spatiotemporal distribution and chemical composition of atmospheric fine particles in areas around the Taiwan Strait were firstly investigated. Fine particles (PM2.5) were simultaneously collected at two sites on the west-side, one site at an offshore island, and three sites on the east-side of the Taiwan Strait in 2013–2014. Field sampling results indicated that the average PM2.5 concentrations at the west-side sampling sites were generally higher than those at the east-side sampling sit...

  17. Frequency of collisions between ion and neutral particles from the cloning characteristics of filamentary currents in an atmospheric pressure helium plasma jet

    International Nuclear Information System (INIS)

    In this paper, a cold He atmospheric pressure plasma jet that is generated using a dielectric barrier discharge configuration device is presented. This device is equipped with double-grounded ring electrodes that are driven by a sinusoidal excitation voltage. The properties of the cloning of filamentous current are studied. The frequency of the collisions between the ion and the neutral particles is calculated by measuring the current phase difference between the filamentous current and its corresponding clone. The frequency of the collisions between the ion and the neutral particles is of the order of 108 Hz. (paper)

  18. Clinical characteristics and molecular genetic analysis of 22 patients with neonatal diabetes from the South-Eastern region of Turkey: predominance of non-KATP channel mutations

    Science.gov (United States)

    Demirbilek, Huseyin; Arya, Ved Bhushan; Ozbek, Mehmet Nuri; Houghton, Jayne A L; Baran, Riza Taner; Akar, Melek; Tekes, Selahattin; Tuzun, Heybet; Mackay, Deborah J; Flanagan, Sarah E; Hattersley, Andrew T; Ellard, Sian; Hussain, Khalid

    2015-01-01

    Background Neonatal diabetes mellitus (NDM) is a rare form of monogenic diabetes and usually presents in the first 6 months of life. We aimed to describe the clinical characteristics and molecular genetics of a large Turkish cohort of NDM patients from a single centre and estimate an annual incidence rate of NDM in South-Eastern Anatolian region of Turkey. Design and methods NDM patients presenting to Diyarbakir Children State Hospital between 2010 and 2013, and patients under follow-up with presumed type 1 diabetes mellitus, with onset before 6 months of age were recruited. Molecular genetic analysis was performed. Results Twenty-two patients (59% males) were diagnosed with NDM (TNDM-5; PNDM-17). Molecular genetic analysis identified a mutation in 20 (95%) patients who had undergone a mutation analysis. In transient neonatal diabetes (TNDM) patients, the genetic cause included chromosome 6q24 abnormalities (n=3), ABCC8 (n=1) and homozygous INS (n=1). In permanent neonatal diabetes (PNDM) patients, homozygous GCK (n=6), EIF2AK3 (n=3), PTF1A (n=3), and INS (n=1) and heterozygous KCNJ11 (n=2) mutations were identified. Pancreatic exocrine dysfunction was observed in patients with mutations in the distal PTF1A enhancer. Both patients with a KCNJ11 mutation responded to oral sulphonylurea. A variable phenotype was associated with the homozygous c.-331C>A INS mutation, which was identified in both a PNDM and TNDM patient. The annual incidence of PNDM in South-East Anatolian region of Turkey was one in 48 000 live births. Conclusions Homozygous mutations in GCK, EIF2AK3 and the distal enhancer region of PTF1A were the commonest causes of NDM in our cohort. The high rate of detection of a mutation likely reflects the contribution of new genetic techniques (targeted next-generation sequencing) and increased consanguinity within our cohort. PMID:25755231

  19. Influence of oxygen gas on characteristics of self-organized luminous pattern formation observed in an atmospheric dc glow discharge using a liquid electrode

    International Nuclear Information System (INIS)

    Self-organized luminous pattern formation is observed in the liquid surface of an atmospheric dc glow discharge using a liquid electrode with a miniature helium flow. The factors affecting pattern formation are the gap length, discharge current, helium mass flow rate and polarity. The pattern shape depends on the conductivity and temperature of the liquid electrode. A variety of patterns were observed by changing the conductivity and temperature of the liquid. We clarified that the self-organized pattern formation depends on the amount of electronegative gas, such as oxygen, in the gas in the electrode gap. When an oxygen gas flow was fed to the liquid surface from the outside in an obliquely downward direction, namely, the amount of oxygen gas on the liquid surface was increased locally, self-organized pattern formation was observed in the region with the increased amount of oxygen gas. When the amount of oxygen in the gas in the gap was changed by using a sheath flow system, the appearance of the pattern changed. The presence of oxygen gas strongly affected the self-organized pattern formation of the atmospheric dc discharge using a liquid anode. (paper)

  20. Characteristics and Influencing Factors of Atmospheric Corrosion of Aluminum in Marine and Coastal Environments%海洋和沿海环境铝大气腐蚀特征及影响因素

    Institute of Scientific and Technical Information of China (English)

    胡晓黎; 韩方运; 牛林; 周少玲; 钱兆红; 赵萌; 陈佳川

    2011-01-01

    Atmospheric environments in marine and coastal regions have the characteristics of high humidity, high salinity and strong corrosivity. The research progresses in the atmospheric corrosion of widely used aluminum and its alloys in marine and coastal environments are reviewed. The corrosion characteristics, mechanisms and environmental factors which affecting the corrosion process are investigated to provide valuable references for modeling the life prediction of materials and taking effective measures for corrosion protection.%海洋和沿海大气环境具有高湿度、高盐度以及腐蚀性强的特点。本文综述了具有广泛应用的铝及铝合金在海洋和沿海环境中大气腐蚀的国内外研究动态和进展,探讨了该腐蚀体系的特征、机理及环境(气象、气候)影响因素,旨在为材料的寿命预测模型化和采取有效的腐蚀防护措施提供有价值的参考。

  1. Research on Change Characteristics of Atmospheric Pollutants in Anqing City from 2007 to 2013%安庆市2007~2013年大气污染物变化特征研究

    Institute of Scientific and Technical Information of China (English)

    余光明; 王磊; 安乐生; 顾洪亮

    2015-01-01

    以安庆市2007~2013年空气污染日值资料为基础,分析了3种大气污染物( PM10、SO2、NO2)不同时间尺度的变化特征,并结合安庆市地面气象日观测资料,研究了污染物浓度与气象因子的变化关系。结果表明:2007~2013年,安庆市首要大气污染物为PM10,3种主要大气污染物的载荷顺序为PM10(82.77μg/m3)>SO2(47.61μg/m3)>NO2(33.95μg/m3);冬季和春季大气污染物浓度较高,夏季最低;相关分析表明风、降水、气温和湿度等是与安庆大气污染物浓度呈显著线性相关的气象因子。%Based on the monitoring data of atmospheric pollution ( daily average concentration of PM10 , SO2 and NO2 ) in An-qing city during 2007~2013, we analyzed the change characteristics of these atmospheric pollutants in different time scales.Combi-ning with the daily observation data of ground meterological factors in Anqing city, the author studied the relationship between pollu-tant concentration and meterological factors.The results indicated that:from 2007 to 2013, the chief atmospheric pollutant in An-qing city was PM10, and the concentration of 3 main atmospheric pollutants revealed the order of PM10 (82.77 μg/m3) >SO2 (47.61 μg/m3)>NO2(33.95 μg/m3).The concentration of atmospheric pollutant was higher in winter and spring, and was the lowest in summer.The results of correlation analysis showed that the concentration of atmospheric pollutant in Anqing city was sig-nificantly linearly correlated with the following meterological factors:wind, rainfall, air temperature and humidity.

  2. [Characteristics of the effect of gamma-irradiation on the amino acid composition of collagen as modified by a gaseous atmosphere].

    Science.gov (United States)

    Duzhenkova, N A; Savich, A V

    1986-01-01

    The comparative changes in the amino acid composition of calf skin collagen after gamma-irradiation (doses from 100 to 1,000 Gy) in aqueous solutions under different gas atmospheres (O2, N2O, H2, vacuum) were investigated. The radiochemical yields of collagen amino acid residues destruction were determined. Under O2 (OH X, O2-) most of amino acids are destroyed with higher yields than under N2O. Leucine, valine, isoleucine, phenylalanine, arginine were the exception because of their high reaction rate constants with OH X and hydroxylation reactions. Under H2 (e-aq, H) and in vacuum (e-aq, OH X) the mechanism of collagen radiolysis changed due to its aggregation; the destruction of those amino acids which have high reaction rate constants with water radiolysis products was mainly observed (phenylalanine, tyrosine, histidine). PMID:3774972

  3. Using environmental and growth characteristics of plants to detect long-term changes in response to atmospheric pollution: some examples from British beechwoods.

    Science.gov (United States)

    Ling, K A

    2003-07-01

    This study uses the Ellenberg system of plant indicator values, along with Grime et al.'s plant growth strategy values, to investigate the nature of temporal changes in the composition of ground flora in two beechwoods in the Cotswolds region of the UK, currently receiving atmospheric inputs of nitrogen in excess of critical loads. The woods, first surveyed in the early 1960s, were resurveyed in 1998 using the original sampling protocol. Temporal changes in the abundance of individual species at Blackstable West Wood indicate changes in light over time, although decreases in sun species, and both increases and decreases in shade species suggest that this change has been patchy. Analysis of changes in plant community as represented by weighted and unweighted quadrat Ellenberg and CSR scores have yielded more significant results. Blackstable West Wood shows increases in nitrophilic, moist-soil and competitive species accompanied by a decline in stress-tolerant species. In Buckholt Top Wood there has been an increase in sun and moist-soil species, a decrease in competitive species and, when weighted Ellenberg scores are considered, an increase in acid-tolerant species. These changes indicate both the impact of woodland management by selective felling and an underlying influence of enhanced atmospheric deposition especially of nitrogen pollutants. It is concluded that quadrat mean scores are a useful tool especially where few individual species have undergone large temporal changes in abundance. However, lack of correlations between quadrat Ellenberg scores for pH and light on one hand, and their equivalents measured in the field, i.e. soil pH and surrogates for light, such as distance to the nearest tree and tree density, suggest that this approach may not be sensitive enough to pick up small-scale, within site variations. Although harder to interpret, plant strategy scores were found to be a useful additional descriptor, encapsulating a plant's response to a range of

  4. Electrophysiological characterisation of KCNQ channel modulators

    DEFF Research Database (Denmark)

    Schrøder, R.L

    the whole-cell configuration by the patch-clamp technique. Voltage-activated KCNQ currents were enhanced by extracellular application of retigabine, and also by the novel BK channel opener Compound 1 (( )-(5-chloro-2-metoxyphenyl)-1.3-didydroxy-3-fluoro-6-(trifluoromethyl)-2H-indol-2-one) (Gribkoff et......Potassium (K+) ion channels are ubiquitously expressed in mammalian cells, and each channel serves a precise physiological role due to its specific biophysical characteristics and expression pattern. A few K+ channels are targets for certain drugs, and in this thesis it is suggested that the KCNQ K......+ channels may be targets for neuroprotective, anti-epileptic and anti-nociceptive compounds. The importance of these channels is underscored by the fact that four out of five KCNQ channel subtypes are involved in severe human diseases. However, the pharmacology of the KCNQ channels is yet poorly understood...

  5. Channel selection for automatic seizure detection

    DEFF Research Database (Denmark)

    Duun-Henriksen, Jonas; Kjaer, Troels Wesenberg; Madsen, Rasmus Elsborg; Remvig, Line Sofie; Thomsen, Carsten Eckhart; Sørensen, Helge Bjarup Dissing

    2012-01-01

    Objective: To investigate the performance of epileptic seizure detection using only a few of the recorded EEG channels and the ability of software to select these channels compared with a neurophysiologist. Methods: Fifty-nine seizures and 1419 h of interictal EEG are used for training and testing...... of an automatic channel selection method. The characteristics of the seizures are extracted by the use of a wavelet analysis and classified by a support vector machine. The best channel selection method is based upon maximum variance during the seizure. Results: Using only three channels, a seizure...... recorded directly on the epileptic focus. Conclusions: Based on our dataset, automatic seizure detection can be done using only three EEG channels without loss of performance. These channels should be selected based on maximum variance and not, as often done, using the focal channels. Significance: With...

  6. 3-m Bathymetric Grid of National Oceanic and Atmospheric Administration (NOAA) Survey H11079 of Great Round Shoal Channel, Offshore Massachusetts (H11079_UTM_B, UTM Zone 19)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA) and the Massachusetts Office of Coastal Zone...

  7. 3-m Hill-Shaded Bathymetric Grid of National Oceanic and Atmospheric Administration (NOAA) Survey H11079 of Great Round Shoal Channel (H11079_UTM_HS, UTM Zone 19)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA) and the Massachusetts Office of Coastal Zone...

  8. Interpretation of Sedimentary Environments from National Oceanic and Atmospheric Administration (NOAA) Survey H12007 in the Vicinity of Cross Rip Channel in Nantucket Sound, Offshore Southeastern Massachusetts (H12007_SEDENV.SHP, Geographic, WGS84)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA), is producing detailed geologic maps of the...

  9. 1-m Bathymetric Grid Generated from National Oceanic and Atmospheric Administration (NOAA) Survey H12007 in the Vicinity of Cross Rip Channel, Nantucket Sound (H12007_GEO, Geographic, WGS84)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA), is producing detailed geologic maps of the...

  10. 1-m Bathymetric Grid Generated from National Oceanic and Atmospheric Administration (NOAA) Survey H12007 in the Vicinity of Cross Rip Channel, Nantucket Sound (H12007_UTM, UTM Zone 19, NAD83)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA), is producing detailed geologic maps of the...

  11. H11079_1MGEO_SSS.TIF: 1-meter Composite Grayscale Image of the Sidescan Sonar Data From National Oceanic and Atmospheric Administration (NOAA) Survey H11079 of the Sea Floor in Great Round Shoal Channel, Offshore Massachusetts (Geographic)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA) and the Massachusetts Office of Coastal Zone...

  12. Grayscale Shaded-Relief GeoTIFF Image Showing the 3-m Bathymetry Generated from National Oceanic and Atmospheric Administration (NOAA) Survey H11079 in Great Round Shoal Channel, Offshore Massachusetts (H11079_UTM_GSHS.TIF, UTM Zone 19)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration (NOAA) and the Massachusetts Office of Coastal Zone...

  13. CHANNEL WIDENING DURING DEGRADATION OF ALLUVIAL RIVERS

    Institute of Scientific and Technical Information of China (English)

    Guangqian WANG; Junqiang XIA

    2001-01-01

    This paper first describes the phenomenon of channel widening during degradation of alluvial rivers,explains the mechanisms of channel widening, and analyzes the stability of cohesive riverbank. Then a one-dimensional mathematical model is developed to simulate the transport of non-uniform suspended sediments, with a sub-model for the simulation of channel widening, and is used to study the process of channel widening during degradation. The effects of different incident flow and sediment conditions and different riverbank material characteristics on channel widening and bed degradation are compared.Finally, main factors that control the deformation processes are identified.

  14. A comparative study on the frequency effects of the electrical characteristics of the pulsed dielectric barrier discharge in He/O2 and in Ar/O2 at atmospheric pressure

    Science.gov (United States)

    Pan, Guangsheng; Tan, Zhenyu; Pan, Jie; Wang, Xiaolong; Shan, Chunhong

    2016-04-01

    In this work, a comparative study on the frequency effects of the electrical characteristics of the pulsed dielectric barrier discharges in He/O2 and in Ar/O2 at atmospheric pressure has been performed by means of the numerical simulation based on a 1-D fluid model at frequencies below 100 kHz. The frequency dependences of the characteristic quantities of the discharges in the two gases have been systematically calculated and analyzed under the oxygen concentrations below 2%. The characteristic quantities include the discharge current density, the averaged electron density, the electric field, and the averaged electron temperature. Especially, the frequency effects on the averaged particle densities of the reactive species have also been calculated. This work gives the following significant results. For the two gases, there are two bipolar discharges in one period of applied voltage pulse under the considered frequency range and oxygen concentrations, as occurred in the pure noble gases. The frequency affects the two discharges in He/O2, but in Ar/O2, it induces a strong effect only on the first discharge. For the first discharge in each gas, there is a characteristic frequency at which the characteristic quantities reach their respective minimum, and this frequency appears earlier for Ar/O2. For the second discharge in Ar/O2, the averaged electron density presents a slight variation with the frequency. In addition, the discharge in Ar/O2 is strong and the averaged electron temperature is low, compared to those in He/O2. The total averaged particle density of the reactive species in Ar/O2 is larger than those in He/O2 by about one order of magnitude.

  15. Simulation of nonstationary phenomena in atmospheric-pressure glow discharge

    Science.gov (United States)

    Korolev, Yu. D.; Frants, O. B.; Nekhoroshev, V. O.; Suslov, A. I.; Kas'yanov, V. S.; Shemyakin, I. A.; Bolotov, A. V.

    2016-06-01

    Nonstationary processes in atmospheric-pressure glow discharge manifest themselves in spontaneous transitions from the normal glow discharge into a spark. In the experiments, both so-called completed transitions in which a highly conductive constricted channel arises and incomplete transitions accompanied by the formation of a diffuse channel are observed. A model of the positive column of a discharge in air is elaborated that allows one to interpret specific features of the discharge both in the stationary stage and during its transition into a spark and makes it possible to calculate the characteristic oscillatory current waveforms for completed transitions into a spark and aperiodic ones for incomplete transitions. The calculated parameters of the positive column in the glow discharge mode agree well with experiment. Data on the densities of the most abundant species generated in the discharge (such as atomic oxygen, metastable nitrogen molecules, ozone, nitrogen oxides, and negative oxygen ions) are presented.

  16. Channel Networks

    Science.gov (United States)

    Rinaldo, Andrea; Rodriguez-Iturbe, Ignacio; Rigon, Riccardo

    This review proceeds from Luna Leopold's and Ronald Shreve's lasting accomplishments dealing with the study of random-walk and topologically random channel networks. According to the random perspective, which has had a profound influence on the interpretation of natural landforms, nature's resiliency in producing recurrent networks and landforms was interpreted to be the consequence of chance. In fact, central to models of topologically random networks is the assumption of equal likelihood of any tree-like configuration. However, a general framework of analysis exists that argues that all possible network configurations draining a fixed area are not necessarily equally likely. Rather, a probability P(s) is assigned to a particular spanning tree configuration, say s, which can be generally assumed to obey a Boltzmann distribution: P(s) % e^-H(s)/T, where T is a parameter and H(s) is a global property of the network configuration s related to energetic characters, i.e. its Hamiltonian. One extreme case is the random topology model where all trees are equally likely, i.e. the limit case for T6 4 . The other extreme case is T 6 0, and this corresponds to network configurations that tend to minimize their total energy dissipation to improve their likelihood. Networks obtained in this manner are termed optimal channel networks (OCNs). Observational evidence suggests that the characters of real river networks are reproduced extremely well by OCNs. Scaling properties of energy and entropy of OCNs suggest that large network development is likely to effectively occur at zero temperature (i.e. minimizing its Hamiltonian). We suggest a corollary of dynamic accessibility of a network configuration and speculate towards a thermodynamics of critical self-organization. We thus conclude that both chance and necessity are equally important ingredients for the dynamic origin of channel networks---and perhaps of the geometry of nature.

  17. Perturbations to the Spatial and Temporal Characteristics of the Diurnally-Varying Atmospheric Boundary Layer Due to an Extensive Wind Farm

    Science.gov (United States)

    Sharma, V.; Parlange, M. B.; Calaf, M.

    2016-08-01

    The effect of extensive terrestrial wind farms on the spatio-temporal structure of the diurnally-evolving atmospheric boundary layer is explored. High-resolution large-eddy simulations of a realistic diurnal cycle with an embedded wind farm are performed. Simulations are forced by a constant geostrophic velocity with time-varying surface boundary conditions derived from a selected period of the CASES-99 field campaign. Through analysis of the bulk statistics of the flow as a function of height and time, it is shown that extensive wind farms shift the inertial oscillations and the associated nocturnal low-level jet vertically upwards by approximately 200 m; cause a three times stronger stratification between the surface and the rotor-disk region, and as a consequence, delay the formation and growth of the convective boundary layer (CBL) by approximately 2 h. These perturbations are shown to have a direct impact on the potential power output of an extensive wind farm with the displacement of the low-level jet causing lower power output during the night as compared to the day. The low-power regime at night is shown to persist for almost 2 h beyond the morning transition due to the reduced growth of the CBL. It is shown that the wind farm induces a deeper entrainment region with greater entrainment fluxes. Finally, it is found that the diurnally-averaged effective roughness length for wind farms is much lower than the reference value computed theoretically for neutral conditions.

  18. Physical and optical characteristics of atmospheric aerosols during ICARB at Manora Peak, Nainital: A sparsely inhabited, high-altitude location in the Himalayas

    Indian Academy of Sciences (India)

    U C Dumka; K Krishna Moorthy; P Pant; P Hegde; Ram Sagar; K Pandey

    2008-07-01

    Collocated measurements of the optical and physical properties of columnar and near-surface aerosols were carried out from Manora Peak, Nainital (a sparsely inhabited, high altitude location, ∼2km above mean sea level, in the Himalayas), during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) under the Geosphere Biosphere Programme of the Indian Space Research Organization (ISRO-GBP). Under this, observational data of spectral aerosol optical depths (AOD), mass concentration of aerosol black carbon (B), mass concentration () and number concentration () of composite (total) aerosols near the surface and meteorological parameters were collected during the period February 15 to April 30, 2006. Though very low (> 0.1 at 500 nm) AODs were observed during clear days, as much as a fourfold increase was seen on hazy days. The Ångström exponent (), deduced from the spectral AODs, revealed high values during clear days, while on hazy days was low; with an overall mean value of 0.69 ± 0.06 for the campaign period. BC mass concentration varied between 0.36 and 2.87 g m−3 and contributed in the range 0.7 to 1.8% to the total aerosol mass. Total aerosol number concentration and BC mass concentration showed diurnal variation with a midnight and early morning minimum and a late afternoon maximum; a pattern quite opposite to that seen in low altitude stations. These are attributed to the dynamics of the atmospheric boundary layer.

  19. Characteristics of Coaxial Dielectric Barrier Discharge at an Atmospheric Pressure with a Swirling Gas Argon/Oxygen Mixture for the Surface Modification of Polyester Fiber Cord

    International Nuclear Information System (INIS)

    A newly developed coaxial dielectric barrier discharge reactor with a length of 1000 mm at an atmospheric pressure was used for plasma treatment of polyester fiber cord in a roll-to-roll manner. In this reactor, swirling mixture gases of oxygen of about 1% and argon with a flow rate of 1.5 L/min to 2.7 L/min ensured the gas usage sparing, discharge uniformity and efficient fiber surface modification. The water contact angle and surface morphology of the treated fiber were measured. The results show that the surface oxygenation is mainly responsible for the wettability improvement of the fiber cord when passing through the plasma zone at a linear speed of 3 m/min to 8 m/min. The specimens of modified-polyester fiber reinforced rubber composite were also prepared for the interfacial shear strength tests. Furthermore, the effect of adding oxygen into argon discharge on the fiber surface oxidation was correlated with optical emission spectroscopy. Finally, the effect of adding oxygen into argon discharge on the kinetic processes of the active species generation were also analyzed.

  20. Research on Composition, Source and Pollution Characteristics of Atmospheric Particulates in Fushun City%抚顺市大气颗粒物的研究进展

    Institute of Scientific and Technical Information of China (English)

    蒲涛猛; 张金生; 李丽华

    2013-01-01

    The research results about pollution characteristics of PM10 and PM2.5 in Fushun city in recent ten years were summarized. In order to further study PM2.5, major pollution sources, characteristics of elements, composition of PM2.5 samples were determined. The results indicate that soil dust, coal smoke dust, exhaust gas, industrial dust, road dust and organic carbon are the main sources of pollution;industrial area, traffic area, residential area and commercial area are the ideal sampling points;the ideal sampling time is according to the season.%对近十年抚顺市 PM10、PM2.5污染特征的研究结果进行总结,为了进一步全面研究 PM2.5确定主要的污染源、各污染源的特征元素、PM2.5的样品成分。总结表明土壤尘、煤烟尘、尾气尘、工业尘、道路尘、有机碳是主要污染源,工业区、交通区、居民区和商业区是理想的采样点区域,理想的采样时间是按季节采样。

  1. Effect of high power CO2 and Yb:YAG laser radiation on the characteristics of TIG arc in atmospherical pressure argon and helium

    Science.gov (United States)

    Wu, Shikai; Xiao, Rongshi

    2015-04-01

    The effects of laser radiation on the characteristics of the DC tungsten inert gas (TIG) arc were investigated by applying a high power slab CO2 laser and a Yb:YAG disc laser. Experiment results reveal that the arc voltage-current curve shifts downwards, the arc column expands, and the arc temperature rises while the high power CO2 laser beam vertically interacts with the TIG arc in argon. With the increase of the laser power, the voltage-current curve of the arc shifts downwards more significantly, and the closer the laser beam impingement on the arc to the cathode, the more the decrease in arc voltage. Moreover, the arc column expansion and the arc temperature rise occur mainly in the region between the laser beam incident position and the anode. However, the arc characteristics hardly change in the cases of the CO2 laser-helium arc and YAG laser-arc interactions. The reason is that the inverse Bremsstrahlung absorption coefficients are greatly different due to the different electron densities of the argon and helium arcs and the different wave lengths of CO2 and YAG lasers.

  2. Exoplanet Atmospheres

    CERN Document Server

    Seager, S

    2010-01-01

    At the dawn of the first discovery of exoplanets orbiting sun-like stars in the mid-1990s, few believed that observations of exoplanet atmospheres would ever be possible. After the 2002 Hubble Space Telescope detection of a transiting exoplanet atmosphere, many skeptics discounted it as a one-object, one-method success. Nevertheless, the field is now firmly established, with over two dozen exoplanet atmospheres observed today. Hot Jupiters are the type of exoplanet currently most amenable to study. Highlights include: detection of molecular spectral features; observation of day-night temperature gradients; and constraints on vertical atmospheric structure. Atmospheres of giant planets far from their host stars are also being studied with direct imaging. The ultimate exoplanet goal is to answer the enigmatic and ancient question, "Are we alone?" via detection of atmospheric biosignatures. Two exciting prospects are the immediate focus on transiting super Earths orbiting in the habitable zone of M-dwarfs, and u...

  3. CHARACTERISTICS OF THE CRUSTAL MAGMA BODY IN THE 2005-2006 ERUPTION AREA AT 9°50'N ON THE EAST PACIFIC RISE FROM 3D MULTI-CHANNEL SEISMIC DATA

    Science.gov (United States)

    Carton, H. D.; Carbotte, S. M.; Mutter, J. C.; Canales, J.; Nedimovic, M. R.; Marjanovic, M.; Aghaei, O.; Xu, M.; Han, S.; Stowe, L.

    2009-12-01

    In the summer of 2008 a large 3D multi-channel seismic dataset (expedition MGL0812) was collected over the 9°50’N Integrated Study Site at the East Pacific Rise, providing insight into the architecture of the magmatic system and its relationship with hydrothermal activity and volcanic/dyking events associated with the 2005-06 eruption. The main area of 3D coverage is located between 9°42’N and 9°57’N, spanning ~28km along-axis, and was acquired along 94 (1 partial) prime lines shot across-axis and each ~24km-long. Pre-processing of the data acquired in this area is now well under way, with significant efforts targeted at amplitude spike removal. Current work focuses on setting up the 3D processing sequence up to the stack stage for a small group of inlines (axis-perpendicular grid lines spaced 37.5m apart) located over the “bull’s eye” site at 9°50’N, a sequence that will subsequently be applied to the whole dataset. At the meeting we will present stacked and migrated sections - inlines, crosslines, time slices - obtained through 3D processing. We will discuss results focusing on the characteristics of the axial magma body, whose detailed structure and along-axis segmentation will be resolved by the 3D data.

  4. Study on ionization characteristics of low power Hall thruster with variable cross-section channel%低功率变截面通道霍尔推力器电离特性

    Institute of Scientific and Technical Information of China (English)

    宁中喜; 张世强; 于达仁

    2011-01-01

    In order to improve the performance of the low power Hall thruster without changing its characteristic size,a thruster with variable cross-section channel is designed to increase the atomic density in the ionization region and enhance the propellant utilization.The results show that the new designed Hall thruster can expand the lower power limit,control the ionization process and increase the propellant utilization.The thrust,specific impulse and efficiency performance can also be improved accordingly under low-power condition.The experimental results show that the plume divergence should be optimized in the further research.%在不改变霍尔推力器特征尺寸的条件下为了提高其低功率时的性能,采用缩小通道局部通流面积的方法,利用增加电离区原子密度来提高工质利用率。实验结果表明,该方法能有效拓展低功率放电范围,控制工质电离过程,增加工质利用率,并提高霍尔推力器在低功率下的推力、比冲和效率性能。羽流发散角优化是后续变截面研究中需要重点关注的问题。

  5. The invention of atmosphere.

    Science.gov (United States)

    Martin, Craig

    2015-08-01

    The word "atmosphere" was a neologism Willebrord Snellius created for his Latin translation of Simon Stevin's cosmographical writings. Astronomers and mathematical practitioners, such as Snellius and Christoph Scheiner, applying the techniques of Ibn Mu'ādh and Witelo, were the first to use the term in their calculations of the height of vapors that cause twilight. Their understandings of the atmosphere diverged from Aristotelian divisions of the aerial region. From the early years of the seventeenth century, the term was often associated with atomism or corpuscular matter theory. The concept of the atmosphere changed dramatically with the advent of pneumatic experiments in the middle of the seventeenth century. Pierre Gassendi, Walter Charleton, and Robert Boyle transformed the atmosphere of the mathematicians giving it the characteristics of weight, specific gravity, and fluidity, while disputes about its extent and border remained unresolved. PMID:26193787

  6. Pluto's atmosphere

    International Nuclear Information System (INIS)

    Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data. 43 references

  7. Atmospheric electricity

    CERN Document Server

    Chalmers, J Alan

    1957-01-01

    Atmospheric Electricity brings together numerous studies on various aspects of atmospheric electricity. This book is composed of 13 chapters that cover the main problems in the field, including the maintenance of the negative charge on the earth and the origin of the charges in thunderstorms. After a brief overview of the historical developments of atmospheric electricity, this book goes on dealing with the general principles, results, methods, and the MKS system of the field. The succeeding chapters are devoted to some aspects of electricity in the atmosphere, such as the occurrence and d

  8. Characteristics of SiO{sub X} thin films deposited by atmospheric pressure chemical vapor deposition using a double-discharge system

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jaebeom [SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon, Kyunggi-do 440-746 (Korea, Republic of); Oh, Jongsik; Gil, Elly [Department of Materials Science and Engineering, Sungkyunkwan University, Suwon, Kyunggi-do 440-746 (Korea, Republic of); Yeom, Geun Young, E-mail: gyyeom@skku.edu [SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon, Kyunggi-do 440-746 (Korea, Republic of); Department of Materials Science and Engineering, Sungkyunkwan University, Suwon, Kyunggi-do 440-746 (Korea, Republic of)

    2012-10-15

    SiO{sub X} thin films were deposited using a gas mixture of hexamethyldisilazane (HMDS)/O{sub 2}/He/Ar from a remote-type dielectric barrier discharges (DBD) source, with/without the additional direct-type DBD just above the substrate (double discharge), and the effect of the double discharge on the characteristics of the SiO{sub X} thin film was investigated. The increase of HMDS flow rate and the decrease of oxygen flow rate in the gas mixture increased the SiO{sub X}-thin-film deposition rate. The improvement of the mechanical properties for SiO{sub X} film, in addition to the increase of deposition rate, is believed to be related not only to the higher gas dissociation because of the higher power deposition but also to the lesser recombination of oxygen atoms and dissociated HMDS due to the shorter diffusion length to the substrate.

  9. On the boundary heating conditions difference in the DNB channels

    International Nuclear Information System (INIS)

    Theoretical and experimental work on DNB in reactor channels is reviewed. The effects of channel characteristics, temperature, heat flux and flow rate on DNB correlations are discussed and relations to burnout are considered

  10. Exploring the atmosphere using smartphones

    CERN Document Server

    Monteiro, Martín; Stari, Cecilia; Cabeza, Cecilia; Marti, Arturo C

    2015-01-01

    The characteristics of the inner layer of the atmosphere, the troposphere, are determinant for the earth's life. In this experience we explore the first hundreds of meters using a smartphone mounted on a quadcopter. Both the altitude and the pressure are obtained using the smartphone's sensors. We complement these measures with data collected from the flight information system of an aircraft. The experimental results are compared with the International Standard Atmosphere and other simple approximations: isothermal and constant density atmospheres.

  11. Effects of modified atmosphere package on physiological characteristics of daemonorops margaritae shoots during storage%气调包装对黄藤笋贮藏期间生理特性的影响

    Institute of Scientific and Technical Information of China (English)

    刘晓蓉

    2011-01-01

    研究体积分数为3%O2、5%CO 2和92%N2的气调处理和不同贮藏温度对黄藤笋生理特性的影响.黄藤笋经气调处理后,分别于8℃和20℃下贮藏,定期测定其褐变度(BD)、呼吸强度、苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、多酚氧化酶(PPO)和过氧化氢酶(CAT)活性等生理指标.结果表明,气调处理结合8℃的低温贮藏,能显著降低黄藤笋的呼吸强度,抑制PAL、POD和PPO活性的上升,保持CAT的活性,延缓褐变的发生,延长保质期.%At different temperature, the effects were studied of modified atmosphere package (MAP) (3% O2 、5% CO2 and 92% N2)on physiological characteristics of daemonorops margaritae shoots. Daemonorops margaritae shoots with controlled atmosphere storage were stored at 8 ℃ and 20 ℃. The changes were determined of browning degree, respiration rate, the activities of phenylalanine ammonia-lyase (PAL), peroxidase(POD), polyphenol oxidase (PPO) and catalase (CAT). The results showed that modified atmosphere package and low temperature(8 ℃) could reduce respiration rate, inhibit the increase of PAL, POD and PPO activity, maintain the activity of CAT, resist browning and prolong the shelf life of daemonorops margaritae shoots.

  12. Atmospheric aerosol characteristics retrieved using ground based solar extinction studies at Mohal in the Kullu valley of northwestern Himalayan region, India

    Indian Academy of Sciences (India)

    Nand L Sharma; Jagdish C Kuniyal; Mahavir Singh; Pitamber P Dhyani; Raj P Guleria; Harinder K Thakur; Pan S Rawat

    2012-02-01

    Aerosol parameters are measured using a ground-based Multi-wavelength Radiometer (MWR) at Mohal (31.90°N, 77.11°E, 1154 m amsl) in the Kullu valley during clear sky days of a seasonal year. The study shows that the values of spectral aerosol optical depths (AODs) at 500 nm and the Ångstrom turbidity coefficient ‘’ (a measure of columnar loading in atmosphere) are high (0.41 ± 0.03, 0.27 ± 0.01) in summer, moderate (0.30 ± 0.03, 0.15 ± 0.03) in monsoon, low (0.19 ± 0.02, 0.08 ± 0.01) in winter and lowest (0.18 ± 0.01, 0.07 ± 0.01) in autumn, respectively. The Ångstrom wavelength exponent ‘’ (indicator of the fraction of accumulation-mode particles to coarse-mode particles) has an opposite trend having lowest value (0.64 ± 0.06) in summer, low (0.99 ± 0.10) in monsoon, moderate (1.20 ± 0.15) in winter and highest value (1.52 ± 0.03) in autumn. The annual mean value of AOD at 500 nm, ‘’ and ‘’ are 0.24 ± 0.01, 1.06 ± 0.09 and 0.14 ± 0.01, respectively. The fractional asymmetry factor is more negative in summer due to enhanced tourists’ arrival and also in autumn months due to the monthlong International Kullu Dussehra fair. The AOD values given by MWR and satellite-based moderate resolution imaging spectro-radiometer have good correlation of 0.76, 0.92 and 0.97 on diurnal, monthly and seasonal basis, respectively. The AODs at 500 nm as well as ‘’ are found to be highly correlated, while ‘’ is found to be strongly anti-correlated with temperature and wind speed suggesting high AODs and turbidity but low concentration of fine particles during hot and windy days. With wind direction, the AOD and ‘’ are found to be strongly anti-correlated, while ‘’ is strongly correlated.

  13. Thermosyphon boiling in vertical channels

    Science.gov (United States)

    Bar-Cohen, A.; Schweitzer, H.

    The thermal characteristics of ebullient cooling systems for VHSIC and VLSI microelectronic component thermal control are studied by experimentally and analytically investigating boiling heat transfer from a pair of flat, closely spaced, isoflux plates immersed in saturated water. A theoretical model for liquid flow rate through the channel is developed and used as a basis for correlating the rate of heat transfer from the channel walls. Experimental results for wall temperature as a function of axial location, heat flux, and plate spacing are presented. The finding that the wall superheat at constant imposed heat flux decreases as the channel is narrowed is explained with the aid of a boiling thermosiphon analysis which yields the mass flux through the channel.

  14. Channeling experiment

    International Nuclear Information System (INIS)

    Channeling of water flow and tracer transport in real fractures in a granite body at Stripa have been investigated experimentally. The experimental site was located 360 m below the ground level. Two kinds of experiments were performed. In the single hole experiments, 20 cm diameter holes were drilled about 2.5 m into the rock in the plane of the fracture. Specially designed packers were used to inject water into the fracture in 5 cm intervals all along the fracture trace in the hole. The variation of the injection flowrates along the fracture were used to determine the transmissivity variations in the fracture plane. Detailed photographs were taken from inside the hole and the visual fracture aperture was compared with the injection flowrates in the same locations. Geostatistical methods were used to evaluate the results. Five holes were measured in great detail. In addition 7 holes were drilled and scanned by simpler packer systems. A double hole experiment was performed where two parallel holes were drilled in the same fracture plane at nearly 2 m distance. Pressure pulse tests were made between the holes in both directions. Tracers were injected in 5 locations in one hole and monitored for in many locations in the other hole. The single hole experiment and the double hole experiment show that most of the fracture planes are tight but that there are open sections which form connected channels over distances of at least 2 meters. It was also found in the double hole experiment that the investigated fracture was intersected by at least one fracture between the two holes which diverted a large amount of the injected tracers to several distant locations at the tunnel wall. (authours)

  15. Gravity wave characteristics in the middle atmosphere during the CESAR campaign at Palma de Mallorca in 2011/2012: Impact of extratropical cyclones and cold fronts

    Science.gov (United States)

    Kramer, R.; Wüst, S.; Schmidt, C.; Bittner, M.

    2015-06-01

    Based on a measuring campaign which was carried out at Mallorca (39.6°N, 2.7°E) as cooperation between Agència Estatal de Meteorologia (AEMET) and Deutsches Zentrum für Luft- und Raumfahrt, engl. 'German Aerospace Center' (DLR) in 2011/2012 (September-January), 143 radiosondes (day and night) providing vertical temperature and wind profiles were released. Additionally, nocturnal mesopause temperature measurements with a temporal resolution of about 1 min were conducted by the infrared (IR) - Ground-based Infrared P-branch Spectrometer (GRIPS) during the campaign period. Strongly enhanced gravity wave activity in the lower stratosphere is observed which can be attributed to a hurricane-like storm (so-called Medicane) and to passing by cold fronts. Statistical features of gravity wave parameters including energy densitiy and momentum fluxes are calculated. Gravity wave momentum fluxes turned out being up to five times larger during severe weather. Moreover, gravity wave horizontal propagation characteristics are derived applying hodograph and Stokes parameter analysis. Preferred directions are of southeast and northwest due to prevailing wind directions at Mallorca.

  16. Experimental study on multi-point autoignition characteristics and influence factors of diesel spray in a controllable active thermo-atmosphere

    Institute of Scientific and Technical Information of China (English)

    DENG Jun; WU ZhiJun; HUANG ChengJie; FENG Wei; LI LiGuang

    2007-01-01

    Auto-ignition characteristics of high-pressure diesel spray in the controllable active thermo-atmos- phere (CATA) were studied with a high-speed camera video system. Multi-point autoignition phenomenon of diesel spray in the CATA was observed and the influence factors of the autoignition were analyzed. The stabilization mechanisms of the spray flame in different coflow temperatures were also discussed. The stabilization of the flames was controlled by different factors: autoignition phenomenon in low coflow temperature and flame spread in high coflow temperature. The test results also show that the autoignition delay depends strongly on the coflow temperature and has nonlinear relationship with the temperature. Autoignition delay decreases by almost 10 ms from 16.9 to 7.1 ms when the coflow temperature increases from 996 to 1048 K and only 4 ms from 1048 to 1101 K. The injection parameters in terms of nozzle diameter, injection pressure and pump speed, have some effects on autoignition delay while these effects depend on the coflow temperature. The significant effect lies in low coflow temperature. The injection parameters influence the autoignition delay because it can shorten the physical delay by improving the spray quality and enlarging the spray angle or penetration rate to improve mixture quality.

  17. Export channel pricing management for integrated solutions

    OpenAIRE

    Roine, Henna; Sainio, Liisa-Maija; Saarenketo, Sami

    2012-01-01

    This article studies systems integrators' export channel pricing management for integrated solutions. We find support from our empirical case study for the notion that a systems integrator's export channel pricing strategy is multidimensional and dependent on international pricing environment and partner characteristics and that export partnerships have unique implications on a systems integrator's pricing process. The results show that giving up pricing control in export channel context may ...

  18. Rapid On-site Qualitative and Quantitative Measure Characteristics Atmospheric Pollutants of Sources by GCMS%污染源大气中特征污染物的现场快速质谱定性、定量

    Institute of Scientific and Technical Information of China (English)

    吉建国

    2013-01-01

    The quality improvement of environment air is not only depended on controlling the content of fine particles in the atmosphere,but also reducing emissions of volatile organic compounds.How to control and reduce volatile organic compounds is based on the data about the types of characteristics atmospheric pollutants in sources and emission volume.Because the concentration and type of pollutants in the atmosphere are influenced by the type of climate,wind,light and other weather conditions,rapid sample collection and rapid on-site qualitative and quantitative analysis by GCMS in the pollutant source sites are very important for the environmental monitoring department and pollution sources controlling department.This article explores how the mobile GC-MS and its associated technologies on fast sampling are applied in rapid qualitative and quantitative analysis applications for characteristics source pollutants in chemical zone.%环境空气质量的改善不但要控制大气中细微颗粒的含量,同时要减少挥发性有机污染物的排放;而控制和减少挥发性有机物的措施实施是基于对污染源特征污染物种类和排放量的理解.鉴于污染源大气中的污染物浓度和种类受气候、风速、光照等气象条件的影响,在污染源现场进行样品的快速采集、快速质谱定性、定量的分析对环保监测部门和污染源的治理部门都有非常重要的现实意义.本文探讨了基于移动式车载气质联用仪和与其相关的各种快速采样技术对化工区污染源特征污染物的快速定性、定量分析应用.

  19. Distribution Characteristics of Particulate Mercury in Atmosphere of Nanjing during Winter%南京市冬季大气颗粒态汞的分布特征

    Institute of Scientific and Technical Information of China (English)

    于学珍; 谢云中; 李贺

    2013-01-01

    采集了南京市2012年冬季4个功能区的PM2.5、PM10、TSP样品,对不同粒径大气颗粒物中的颗粒态汞测试。结果表明,南京冬季大气颗粒物TSP中汞的质量浓度为49.26 pg/m3~257.14 pg/m3,平均质量浓度为161.27 pg/m3;PM10中汞的质量浓度为44.82 pg/m3~228.29 pg/m3,平均质量浓度为147.38 pg/m3;PM2.5中汞的质量浓度为35.98 pg/m3~178.58 pg/m3,平均质量浓度为104.10 pg/m3。不同功能区大气颗粒态汞质量浓度的分布趋势为:交通综合区>旅游区>住宿综合区>商业区。大气颗粒态汞60%以上存在于可吸入肺的PM2.5中,细颗粒物富集汞的能力比粗颗粒物强。%The samples of the PM2.5, PM10, TSP were collected in four functional sites of Nanjing during winter in 2012 , and the particular mercury concentrations in different size were analyzed .The results indicated that the mercury concentrations of TSP were 49.26 pg/m3 ~257.14 pg/m3 , the average concentration was 161.27 pg/m3.The mercury concentrations of PM10 were 44.82 pg/m3 ~228.29 pg/m3, the average concen-tration was 147.38 pg/m3.The mercury concentrations of PM2.5 were 35.98 pg/m3 ~178.58 pg/m3, the aver-age concentration was 104 .10 pg/m3 .The sequence of atmospheric particulate mercury concentration in different functional areas was:traffic district >tourist area >residential district >business district .More than 60%of particulates mercury was combined with fine aerosol , which can be inhaled into the lungs .The fine particulate matters enrich mercury much easier than the coarse particles .

  20. Quartz Channel Fabrication for Electrokinetically Driven Separations

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, D.W.; Ashby, C.I.H.; Bailey, C.G.; Kravitz, S.H., Warren, M.E.; Matzke, C.M.

    1998-12-01

    For well resolved electrokinetic separation, we L tilize crystalline quartz to micromachine a uniformly packe Q&iKLmnel. Packing features are posts 5 Vm on a side with:} pm spacing and etched 42 Vm deep. In addition to anisotropic wet etch characteristics for micromachining, quartz propmties are compatible with chemical soiutioits, ekctrokinetic high voltage operation, and stationary phase film depositions. To seal these channels, we employ a room temperature silicon-oxynhride deposition to forma membrane, that is subsequently coated for mechanical stability. Using this technique, particulate issues and global warp, that make large area wafer bon ding methods difficult, are avoided, and a room temperature process, in contrast to high temperature bonding techniques, accommodate preprocessing of metal films for electrical interconnect. After sealing channels, a number of macro-assembly steps are required to attach a micro-optical detection system and fluid interconnects. Keywords: microcharmel, integrated channel, micromachined channel, packed channel, electrokinetic channel, eleetrophoretic channel

  1. Articulating Atmospheres

    DEFF Research Database (Denmark)

    Kinch, Sofie

    2011-01-01

    This paper presents an architectural approach to designing computational interfaces by articulating the notion of atmosphere in the field of interaction design. It draws upon the concept of kinesthetic interaction and a philosophical notion on atmosphere emphasizing the importance of bodily...... experience in space, presented as middle ground experience. In the field of HCI, middle ground experiences complete the unarticulated spectrum between designing for foreground of attention or background awareness. When “Articulating Atmospheres through Middle Ground Experiences in Interaction Design......” implications and qualities of the approach are identified through concrete examples of a design case, which also investigates the qualities and implications of addressing atmospheres both as design concern and user experience....

  2. Exoplanetary Atmospheres

    CERN Document Server

    Madhusudhan, Nikku; Fortney, Jonathan; Barman, Travis

    2014-01-01

    The study of exoplanetary atmospheres is one of the most exciting and dynamic frontiers in astronomy. Over the past two decades ongoing surveys have revealed an astonishing diversity in the planetary masses, radii, temperatures, orbital parameters, and host stellar properties of exoplanetary systems. We are now moving into an era where we can begin to address fundamental questions concerning the diversity of exoplanetary compositions, atmospheric and interior processes, and formation histories, just as have been pursued for solar system planets over the past century. Exoplanetary atmospheres provide a direct means to address these questions via their observable spectral signatures. In the last decade, and particularly in the last five years, tremendous progress has been made in detecting atmospheric signatures of exoplanets through photometric and spectroscopic methods using a variety of space-borne and/or ground-based observational facilities. These observations are beginning to provide important constraints...

  3. Staging atmospheres

    DEFF Research Database (Denmark)

    Bille, Mikkel; Bjerregaard, Peter; Sørensen, Tim Flohr

    2015-01-01

    . Nevertheless, people’s experience of the environment is sought manipulated in a variety of contexts, often without offering a less ‘true’ experience of a situation than if it had not been manipulated by people. In fact, orchestrations of space are often central to sociality, politics and aesthetics. This...... introduction seeks to outline how a number of scholars have addressed the relationship between staged atmospheres and experience, and thus highlight both the philosophical, social and political aspects of atmospheres...

  4. 东亚北部地区气温的冬季-冬季再现特征研究∗%Characteristics of winter-to-winter recurrence of atmospheric temp erature in the northern area of East Asia

    Institute of Scientific and Technical Information of China (English)

    王晓娟; 乔少博; 沈柏竹; 封国林

    2014-01-01

    Seasonal evolution of atmospheric temperature with winter-summer-the following winter (winter-to-winter) char-acteristics in the northern area of East Asia (40—50◦N, 100—130◦E) from 1953 to 2012 has been investigated in this paper. Results indicate that: from 2008 on, the atmospheric temperature in this area had a typical characteristic of cold winter-warm summer-the following cold winter for three consecutive years from the lower layer to the upper layer (1000—400 hPa), and the similar situation also appeared in the period from 1950s to 1960s;however, the opposite vari-ation characteristics of warm winter-cool summer-the following warm winter happened in 1990s. This typical seasonal evolution of atmospheric temperature was defined as a new variation mechanism: winter-to-winter recurrence (WWR). The recent 60 years may be divided into four different types according to the variation of the years from 1953 to 2012:negative (positive) winter-to-winter recurrence (negative/positive WWR) and negative (positive) non winter-to-winter recurrence (negative/positive non-WWR). In the 23 WWR years the probability of occurrence was close to 40%. This WWR characteristic still exists and is independent of the variation of the El Niño southern oscillation index. The synthetic anomalies analysis of geopotential height, vertical speed, and the winter vector at 850 hPa indicates that as for the WWR pattern, the dynamic process of inner atmosphere also has WWR characteristics corresponding to the atmospheric temperature from the lower layer (1000 hPa) to the upper layer (500 hPa) while the non-WWR pattern does not have the similar characters. This study will provide a new idea to further investigate the frequent occurrence of the winter low temperature events on the background of global warming.%对东亚北部(40—50◦N,100—130◦E)区域1953—2012年大气温度的冬季-夏季-次年冬季(简称冬季-冬季)的季节变化特征进行了

  5. 四川盆地大气NO2特征研究%Characteristics of atmospheric NO2 over Sichuan basin

    Institute of Scientific and Technical Information of China (English)

    肖钟湧; 江洪

    2011-01-01

    The temporal-spatial characteristics of the tropospheric column NO2 (TroNO2) and total column NO2 (TotNO2) over Sichuan basin since 2004 had been analyzed based on remote sensing data derived from ozone monitoring instrument (OMI) sensor. The regional mean of TroNO2 and TotNO2 over Sichuan basin had an increasing trend, with annual increasing rates 5.12% and 3.42%, respectively. The variations of TroNO2 and TotNO2 were similar pattern, and the correlation between TroNC2 and TotNO2 was closely relative. For the temporal dynamics, the TroNO2 and TotNO2 in spring and summer were larger than those of autumn and winter. The smallest and largest ratio of TroNO2 to TotNO2 appeared in June and December with about 0.51 and 0.66, respectively. The monthly variation of ratio associated closely with the anthropogenic emission. The large values appeared in the urban region of Chongqing and Chengdu, which the economic develop rapidly and air pollution were serious. Especially, the multi-year mean TroN02 was more distinctive, they were about 10.52xl015 and 8.92xlO15 molec/cm2, respectively. The variation trend of TroNO2and TotNO2 presented strongly correlation With correlation coefficient (R) higher than 0.95 (ratio larger than 0.5) in most region, and the correlation coefficients were approximate to be 1 (ratio larger than 0.8) in the urban region of Chongqing and Chengdu. It proved that the effect of anthropogenic emission was the dominant factor in this regional NO2 concentration upper.%利用臭氧观测仪(OMI)卫星遥感反演的NO2柱密度数据,分析了2004年以来四川盆地对流层NO2柱密度和总NO2柱密度的时空特征.结果表明,对流层NO2柱密度和总NO2柱密度呈逐渐上升的趋势,年平均增长率分别约为5.14%和3.42%,而且对流层NO2柱密度的变化特征和总NO2柱密度的相似(r=0.91).春、夏季对流层NO2柱密度和总NO2柱密度明显大于秋、冬季,对流层NO2柱密度与总NO2柱密度

  6. Impact of Measurement System Characteristics on Advanced Sounder Information Content

    Science.gov (United States)

    Larar, Allen M.; Liu, Xu; Zhou, Daniel K.

    2011-01-01

    Advanced satellite sensors are tasked with improving global observations of the Earth's atmosphere, clouds, and surface to enable enhancements in weather prediction, climate monitoring capability, and environmental change detection. Achieving such an improvement in geophysical information inferred from these observations requires optimal usage of data from current systems as well as instrument system enhancements for future sensors. This presentation addresses results of tradeoff studies evaluating the impact of spectral resolution, spectral coverage, instrument noise, and a priori knowledge on remote sensing system information content, with a specific emphasis on thermodynamic state and trace species information obtainable from advanced atmospheric sounders. Particular attention will be devoted toward information achievable from the Atmospheric InfraRed Sounder (AIRS) on the NASA EOS Aqua satellite in orbit since 2002, the Infrared Atmospheric Sounding Interferometer (IASI) aboard MetOp-A since 2006, and the Cross-track Infrared Sounder (CrIS) instrument to fly aboard the NPP and JPSS series of satellites expected to begin in late 2011. While all of these systems cover nearly the same infrared spectral extent, they have very different number of channels, instrument line shapes, coverage continuity, and instrument noise. AIRS is a grating spectrometer having 2378 discrete spectral channels ranging from about 0.4 to 2.2/cm resolution; IASI is a Michelson interferometer with 8461 uniformly-spaced spectral channels of 0.5/cm (apodized) resolution; and CrIS is a Michelson interferometer having 1305 spectral channels of 0.625, 1.250, and 2.50/cm (unapodized) spectral resolution, respectively, over its three continuous but non-overlapping bands. Results of tradeoff studies showing information content sensitivity to assumed measurement system characteristics will be presented.

  7. Atmospheres of Brown Dwarfs

    CERN Document Server

    Helling, Christiane

    2014-01-01

    Brown Dwarfs are the coolest class of stellar objects known to date. Our present perception is that Brown Dwarfs follow the principles of star formation, and that Brown Dwarfs share many characteristics with planets. Being the darkest and lowest mass stars known makes Brown Dwarfs also the coolest stars known. This has profound implication for their spectral fingerprints. Brown Dwarfs cover a range of effective temperatures which cause brown dwarfs atmospheres to be a sequence that gradually changes from a M-dwarf-like spectrum into a planet-like spectrum. This further implies that below an effective temperature of < 2800K, clouds form already in atmospheres of objects marking the boundary between M-Dwarfs and brown dwarfs. Recent developments have sparked the interest in plasma processes in such very cool atmospheres: sporadic and quiescent radio emission has been observed in combination with decaying Xray-activity indicators across the fully convective boundary.

  8. Numerical simulation research into atmospheric characteristics influenced by Qinghai Lake in the process of local snowfall%青海湖对局地降雪过程中大气特征影响的数值模拟

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      采用敏感性数值试验的方法,选取发生在青海湖及其附近区域的2次降雪过程,利用非静力中尺度数值模式WRF V3.2,对比分析了青海湖水体分布改变前后局地大气动力和热力特征的变化.结果表明:青海湖在局地近地层有明显的“湖陆风”特征;青海湖水体对局地降雪过程的降雪有一定的增强作用;青海湖水体面积的变化对于改变局地大气的湿度场、动力场、温度场有重要的作用;受大气日变化特征的影响,青海湖水体对降雪的影响机制在白天和夜晚存在差异;青海湖水体的存在,影响的水平范围约为30 km;在垂直方向上,青海湖水体会使白天的边界层高度降低约900 m,夜间增高约300 m.%The effect of Qinghai Lake on the local atmospheric characteristics was studied through sensitivity experiments with mesoscale model WRF V3.2 for the selected snowfall cases around Qinghai Lake and the main results are that the character of lake-land breeze was obvious around Qinghai Lake and that its water body enhanced the regional precipitation during the snowfall process around it. The sensitivity experiments on area changing around the lake indicate that it had an important effect on the local atmospheric humidity field, dynamic and term-dynamic field and the effect of the lake on the mechanism of precipitation was different with the daily variation of atmosphere. The horizontal impact range of the the lake was about 30 km while vertically speaking, Qinghai Lake could decrease the planetary boundary layer height by about 900 m during the day and increase it by about 300 m at night.

  9. Multi-Channel Maximum Likelihood Pitch Estimation

    DEFF Research Database (Denmark)

    Christensen, Mads Græsbøll

    2012-01-01

    . This essentially means that the model allows for different conditions in the various channels, like different signal-to-noise ratios, microphone characteristics and reverberation. Moreover, the method does not assume that a certain array structure is used but rather relies on a more general model and......In this paper, a method for multi-channel pitch estimation is proposed. The method is a maximum likelihood estimator and is based on a parametric model where the signals in the various channels share the same fundamental frequency but can have different amplitudes, phases, and noise characteristics...

  10. Channel strategy adaptation

    OpenAIRE

    Rangan, V. Kasturi; Nueno, Jose L

    1999-01-01

    Using transaction cost theory, considerable research in marketing has focused on the conditions under which firms would use direct or vertically integrated versus indirect or arms length channels of distribution. Data from the field, however, indicate that channel configurations are more varied and complex, with multiple channels and composite channels being just as common as direct and indirect channels. In an attempt to explain this variety, this paper revisits the influence on channel stru...

  11. Atmospheric thermodynamics

    CERN Document Server

    Iribarne, J V

    1973-01-01

    The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...

  12. Atmospheric Smell

    DEFF Research Database (Denmark)

    Stenslund, Anette

    awareness. Subsequently, visitor interviews revealed how a museum-staged hospital atmosphere of an art installation was directly addressed owing to its smell. Curiously, this observation speaks against prevailing literature portraying smell as the ‘mute sense’, and what is more, the museum display did not...... alter smell curatorially. Rather, smell was gestured through non-olfactory effects and it was put in words metonymically, gesturing a reversibly synaesthetic atmosphere of a hospital. Visitor conversations revealed how smell could be poignantly picked up in situ, yet not until frequenting the museum...

  13. Effect of molybdenum addition on aluminium grain refined by titanium on its metallurgical and mechanical characteristics in the as cast condition and after pressing by the equal angular channel process

    International Nuclear Information System (INIS)

    Aluminium and its alloys are versatile materials which are widely used in industrial and engineering applications due to their attractive characteristics. However, they solidify in columnar structure which tends to reduce their surface quality and mechanical strength. It is therefore, grain refined by grain refiners i.e. titanium or titanium+boron. The equal angular channel pressing, ECAP, process is a recent method for producing severe plastic deformation in materials. In this research work, the effect of addition of molybdenum either alone or in the presence of titanium to commercially pure aluminium on microstructure and mechanical behaviour is investigated in two conditions; first, in the as cast condition, and second after pressing by the ECAP process at room temperature. It was found that addition of Ti alone at a rate of 0.15% weight to commercially pure Al resulted in grain refining of microstructure and a grain size of 91μm was obtained. However, after pressing by the ECAP process further refinement was achieved and the grain size was reduced to 18μm. Addition of Mo alone to aluminium at a rate of 0.1% resulted in grain size of 76μm in the as cast condition and 32μm after pressing by the ECAP process. The combination of the two elements Ti and Mo together resulted in 48μm grain size in the as cast condition, compared to 40μm after pressing by the ECAP process. Furthermore, it was found that in the as cast condition: addition of Ti alone to Al resulted in enhancement of its mechanical behaviour by an increase of 5.2% increase in its flow stress at 20% true strain, whereas addition of Mo either alone or in the presence of Ti resulted in decrease of its flow stress at 20% by 9% and 5.6% respectively. However, after pressing by ECAP: it was found that addition of Ti or Mo either alone or together to Al resulted in increase of its flow stress at 20 % strain by the following percentages 5.49, 4.74 and 10.3% respectively

  14. Concurrent signal combining and channel estimation in digital communications

    Science.gov (United States)

    Ormesher, Richard C.; Mason, John J.

    2011-08-30

    In the reception of digital information transmitted on a communication channel, a characteristic exhibited by the communication channel during transmission of the digital information is estimated based on a communication signal that represents the digital information and has been received via the communication channel. Concurrently with the estimating, the communication signal is used to decide what digital information was transmitted.

  15. Channel Islands, Kelp Forest Monitoring, Size and Frequency, Natural Habitat

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has measurements of the size of selected animal species at selected locations in the Channel Islands National Park. Sampling is conducted annually...

  16. Compact, Dual Channel, Mid-IR Laser Spectrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Small Business Innovative Research Phase I proposal seeks to develop a dual channel, compact mid-infrared laser spectrometer for planetary atmosphere...

  17. Compact, Dual Channel, Mid-IR Laser Spectrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Small Business Innovative Research Phase II proposal seeks to develop a dual channel, compact mid-infrared laser spectrometer for planetary atmosphere...

  18. Channel Islands, Kelp Forest Monitoring, Survey, Fish Transect

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset from the Channel Islands National Park's Kelp Forest Monitoring Program has measurements of the abundance of fish species. The original measurements...

  19. Channel Islands, Kelp Forest Monitoring, Survey, Random Point Contact

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset from the Channel Islands National Park's Kelp Forest Monitoring Program has estimates of substrate composition and percent cover of selected algal and...

  20. Channel Islands, Kelp Forest Monitoring, Survey, 1m Quadrat

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset from the Channel Islands National Park's Kelp Forest Monitoring Program has measurements of the abundance (density) of relatively abundant selected...